JP2002517710A - Method and apparatus for confocal interference microscopy using wavenumber domain reflectometer and background amplitude reduction and compensation - Google Patents

Abstract

(57) Abstract: An in-focus image of an object (112) and / or an area on the object is obtained by generating a probe beam (P22B) and a reference beam (R22B) from a broadband point light source (90). It is identified from the out-of-focus image to reduce errors in the image information of interest. At this time, an antisymmetric spatial characteristic is generated in the reference beam (R32B), the probe beam is converted into a beam focused on a line in the region, a focus return probe beam is generated, and the focus return probe beam (P32B) is generated. ) To generate an antisymmetric spatial characteristic. Next, the refocused probe beam is spatially filtered (P42A) and passed through a dispersive element to focus it (P42A) on a line in the detector plane of the detector system (114). The reference beam is spatially filtered (R42A) and passed through a dispersive element to focus it (R42A) on a line in the detector plane. The beam from the out-of-focus image point is spatially filtered (P62A) and passed through a dispersive element (P62C). The spatially filtered reference beam (R42C) in the detector plane is interfered with the spatially filtered beam from the out-of-focus image point (P62C) and the in-focus probe beam (P42C) in the detector plane. You. The amplitude of the spatially filtered focused return probe beam (P42C) is calculated as the interference term between the spatially filtered focused return probe beam (P42C) and the reference beam (R42C) in the detector plane. Detected by system (114). This substantially reduces the amplitude of the interference terms between the amplitudes of the out-of-focus image beam (P62C) and the reference beam (R42C), which are spatially filtered in the detector plane, and are detected to represent image information of interest. Error in the data generated by the detector system (114).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD OF THE INVENTION

The present invention relates to optical and acoustic imaging, and uses such images to
Includes storing and retrieving optical data, and performing precision measurements on biological samples, wafers, integrated circuits, optical disks, and other samples.

[0002]

[Prior art]

The present invention is a technique for quickly and accurately generating an in-focus image of an object or an object cross-section, wherein the effects of light signals from out-of-focus foreground and / or background light sources are the best with respect to both statistical and systematic errors. Regarding technologies to be excluded. Confocal and confocal interference microscopes are finding many applications, for example, in the fields of life sciences, biological sample research, industrial inspection, and semiconductor metrology. This is due to the unique imaging capabilities of these technical tools.

[0003] Probably the most difficult multidimensional image processing is faced when the background from the out-of-focus image becomes significantly larger than the signal from the focused image. Such an environment
It frequently occurs during the study of thick samples, especially when working in the reflection mode as opposed to the propagation mode of a confocal system.

[0004] There are two general approaches for determining the volume properties of a three-dimensional microscopic specimen. Such an approach is based on conventional and confocal microscopes. In general, conventional microscopy approaches require less time to acquire data than approaches to confocal microscopes, but require more time to process data for a three-dimensional image.

In conventional image processing systems, when a portion of the object to be imaged is displaced on its optical axis from its best focus position, its image contrast decreases, but its brightness remains constant. , The displaced out-of-focus portion of the image interferes with the field of focus of the object.

[0006] The point-spread function of the system is known, and if an image is obtained for each independent section of the object, the signal contributed by out-of-focus light can be efficiently reduced. Well-known computer algorithms can be applied to such images to remove them and produce images containing only in-focus data. Such algorithms consist of several distinct types, termed "computer-deconvolutions", and are generally expensive in computer equipment, as well as considerable in order to obtain the desired statistical accuracy. Requires computer processing time and a significant amount of data.

The wide field method (WFM) (proc. Soc. PhotoOpt.
Instrum. Eng., SPIE, 1980, 264, pp. 110-117. A. Agard and J
. W. "3D Analysis of Biological Specimens Using Image Processing Technology" by Sedat, Anal
Biochem. 1981, 111, pp. 257-268. A. Agard, R.A. A. Steinberg, "Quantitative Analysis of Electrophoretograms: A Mathematical Approach to Superresolution", Methods Cell Biol. 1989, 30 pp. 353-377. A
. Agard, Y. Hiraoka, p. Shaw and J.C. W. "3D Fluorescence Microscopy" by Sedat, Annue. Rev. Biophys. Bioeng.
. A. Agard, "Optically Comparted Microscopes", Sci. 1987, 238, pp. 36-41. Hiraoka, J.M. W. Sedat and D.S. A. Agard, "Use of Charge-Coupled Devices for Quantitative Light Microscopy of Biological Structures," Sci. 1990 248 No. 73.
Page to page 76 Denk, J.C. H. Strinkler and W.C. W. "2
In a "photon laser scanning fluorescence microscope"), conventional microscopes are used to sequentially acquire sets of images of adjacent focal planes over the volume of interest. Each image is a cooled charge-coupled device (CCD) image sensor (
Sci. Am. 1982 247, pp. 67-74 Christian and M.S. It is recorded by using the "Charge Coupled Device in Astronomy" by Bruke) and contains data from both the in-focus and out-of-focus image planes.

[0008] Laser computed tomography techniques are performed using a conventional microscope. Supplied in Appl. Opt. No. 29, pp. 3805-3809 (1990). Kawata, O. Nakamura, T. Noda, H .; Ohki, K. Ogino, Y
. Kleiwa and S.A. The system discussed by Minami in "Microscopes for Computed Tomography Using Lasers" is closely related to the technology of computed tomography radiography using X-rays, but it is called reconstruction of two-dimensional slices. Rather, a three-dimensional volume reconstruction is used. Projection images of the thick three-dimensional sample are collected with a conventional propagation microscope modified with oblique illumination optics, and the three-dimensional configuration inside the sample is reconstructed by a computer. Here, this data is obtained within a short time as compared with the time required to process data for a three-dimensional image. In one experiment by Kawata et al. (Cited above), an 80 × 80 × 36-voxel was used.
Reconstruction required several minutes to collect all projection data and send them to a small computer. Next, digital reconstruction of the image took about 30 minutes, despite the use of a vector operation processor at an operation speed of 20 mega-floating point operations per second (MFLOPS).

In a conventional point or pinhole type confocal microscope, light from a point light source
It is focused in a very small space known as a so-called spot. The microscope focuses light scattered and reflected from the spot, or light propagating through the spot over the point detector. In a reflection point-confocal microscope, the incident light is reflected, or backscattered, by that portion of the sample in the spot.
Light reflected or backscattered by the sample outside the spot is not well focused on the detector, and thus the light is diffused so that the detector is not reflected or backscattered. Only a small portion of the light will be received. In a propagating point-confocal microscope, incident light is propagated unless it is scattered or absorbed by that portion of the sample in the spot. Generally, point light sources and point detectors are made closer by placing a mask with a pinhole in front of the conventional light source and the conventional detector, respectively.

[0010] Similarly, in a conventional slit confocal microscope system, light from a line light source is focused into a very narrow elongated space, also known as a spot. Slit confocal microscopes focus light on a line detector that is reflected from, scattered by, or transmitted through a spot. The line light source and line detector can be approximated using a slit on the front of a conventional light source and an array of conventional detectors, respectively. Alternatively, the line light source can sweep and approximate a laser beam focused over the object to be imaged or inspected.

Since only a small part of the object is imaged by the confocal microscope, it must be imaged in order to obtain enough image data to produce a complete two-dimensional or three-dimensional image of the object You must either move the object or move the light source and detector. Previous slit confocal systems have moved an object along a straight line perpendicular to the slit to obtain a continuous linear portion of the two-dimensional image data. On the other hand, point confocal systems with only one pinhole are moved in a two-dimensional manner to obtain two-dimensional image data and three-dimensional in order to obtain a set of three-dimensional image data. Must be moved. Raw image data is typically stored and subsequently processed to form a two-dimensional cross-section or three-dimensional image of the object to be inspected or imaged. Reducing the sensitivity to out-of-focus images relative to conventional microscopes leads to improved statistical accuracy for a given amount of data, and this processing operation is based on the data obtained with the conventional microscope approach. Is much simpler than the operations required when processing

In a system known as a tandem scanning optical microscope (TSOM), the helical pattern of illumination and the detector pinholes are etched into a Nipkow disk as the disk rotates and are completely etched. The object fixed to is scanned in two dimensions [J
Opt. Soc. A. 58 (5), pages 661 to 664 (1968). Petlan and G.E. S. "Tandem scanning reflected light microscope" by Kino and Appl. Phys. Lett.
No. 53, pages 716 to 718 (1988). Q. Kisiano, T.A. R. Corle,
And G. S. See Kino's "Real-time confocal scanning optical microscope." In terms of optical processing, the TSOM is basically a single-point confocal microscope with means for efficiently scanning a two-dimensional section one point at a time.

Two techniques implemented to reduce the amount of scanning required when obtaining a two-dimensional image in a confocal configuration are described in Appl. Opt. No. 33 (4), pp. 567-572. (
1994). J. Tiziani and H.E. -M. Ude's work on "3D analysis by confocal construction of microlens array" Kirstens, J
. R. Mandeville and F.M. Y. U.S. Pat. No. 5,248,876, issued to Wu, entitled "Tandem Linear Scanning Confocal Imaging System with Focal Volumes at Different Heights", issued in September 1993. It is. The above-referenced Tiziani and Oude microlens array confocal configurations have the same out-of-focus image discrimination capability as when using a multiple pinhole source and a detector with multiple elements in a confocal configuration. Such a system allows a large number of points to be examined simultaneously, but compromises on identification for out-of-focus images. The higher the density of the microlenses, the lower the ability of the system to discriminate against out-of-focus images, and consequently the complexity of the computer-deconvolution required to generate three-dimensional images and Increase costs. Furthermore, the Tiziani and Oude systems cited above have significant limitations on axial range. This range cannot exceed the microlens focal length, which is proportional to the microlens diameter defined for a given numerical aperture. Thus, as the number of microlenses increases, the axial range allowed in this connection decreases.

The above-cited Kirstains et al. System incorporates a large number of pinholes and precisely aligns the detector in a confocal configuration to allow multiple points to be examined simultaneously. However, as explained in the previous paragraph, this gain compromises on identification for out-of-focus images, thereby increasing the required time-consuming computer-deconvolution complexity and cost. . The higher the density of pinholes, the lower the system's ability to discriminate against out-of-focus images. The best discrimination will be achieved when using only one pinhole.

[0015] Applying a confocal microscope to the inspection of electronics requires microelectronics
Engineering No. 5, pages 573 to 580 (1986). Zaffe and R.A. W. "Confocal Laser Microscope for Microstructural Measurement" by Wiener En-Von-Lessan and SPIE, 565, pp. 81-87 (198
J. described in 5). T. Gentian, S. D. Bennett and I.S. R. Proposed in Smith, "Scanning laser image processing for integrated circuit metrology". The on-axis identification provided by the confocal system is useful in a semiconductor manufacturing environment. For example, such a system could be provided to improve inspection of height dependent features such as delamination, air bubbles, and thickness of structures and coatings. However, there are some problems associated with using confocal imaging systems for electronics inspection. For example, a single pinhole system would have 2
It takes a very long time to scan an object in a dimension. Optical systems for scanning a laser beam onto an object are very complex. And the above-mentioned TSOM
The approach with a rotating disk used in the above creates problems in alignment and maintenance.

The number of slices of different depths required (and thus the amount of image data collected) depends on the range of heights that have to be measured, and the required height resolution of the optical system And performance. In a typical electronics inspection, slice images of 10 to 100 different depths would be required. In addition, some color band data may be needed to identify the material. In confocal imaging systems, a separate two-dimensional scan is required for each desired height. If multiple color band data is desired, multiple two-dimensional scans at each height are required. By shifting the focus level, similar data can be obtained from adjacent planes and a set of three-dimensional intensity data can be obtained.

Thus, none of the prior art confocal microscope systems can constitute a rapid and / or reliable three-dimensional tomography image processing system, especially in the field of inspection or imaging.

Although the confocal approach works better and more directly, for example in the case of confocal fluorescence, when the density of mottled structures is high, the approach using a conventional microscope is still Have advantages. The most important of these is that the latter can utilize dyes that are excited in the ultraviolet (UV) range, which are often more robust and efficient than dyes that are excited in the visible range. That seems to be. Ultraviolet lasers can be incorporated as light sources for confocal microscopes [J. Microsc (Oxford) 1991 163 (Pt. 2), pp. 201-210. Montag, J.M. Cruise, R.A. Jorgens, H.C. Gundrach, M .; F. Trendelenburg and H.E. Spring "Working with a Confocal Scanning Ultraviolet Laser Microscope: Positioning Specific DNA with High Sensitivity and Multiparameter Fluorescence"; Neurosci. Res. 1991, 10 pp. 245-259 K
. Kuba, S.M. -Y. Hua and M.S. "Spatial and dynamic changes in Ca2 ⁺ between cells measured by confocal laser scanning microscopy in bullfrog exchanged ganglion cells"; Microscience Journal (J. Microsc) 1993, 169 (Pt. 1), pp. 15-26
Page C. Britton, J.M. Relighters and D.I. E. FIG. "Optical modification enabling simultaneous confocal imaging with dyes excited by ultraviolet and visible wavelength light" by Clappham], or UV dyes in "two-photon" technology (W. Denck cited above). , Etc.) can be excited with infrared (IR) light. These techniques are rather expensive and have practical difficulties.

Furthermore, cooled CCD detectors used in conventional microscope systems collect data in parallel rather than in series, as does a photomultiplier tube (PMT) in a confocal microscope system. As a result, if a CCD can be made to read more quickly without degrading its performance, the three-dimensional data recording rate of a conventional microscope system will depend on the time required for the computer-deconvolution operation, It has been found that even if the delay time is added before the data can be actually viewed as a three-dimensional image, it is significantly higher than the recording rate of the confocal microscope system.

When selecting between a CCD detector used to record a two-dimensional data stream in parallel and a slit or pinhole confocal microscope, the S / N associated with statistical accuracy
The ratio must also be taken into account. The good capacity of a two-dimensional CCD pixel is
It has an order of 200,000 electrons. This limits the statistical accuracy that can be achieved with a single exposure, as compared to the statistical accuracy that can be achieved with other optical radiation detectors, such as those of the PMT or photovoltaic devices. As a result, the contribution of the out-of-focus background is significantly greater than the focused image signal. For those applications, the S / N ratio consideration is the same as the slit confocal, while all other considerations are equivalent. The one-dimensional parallel recording of data in a microscope works better than the two-dimensional recording of data in a standard microscope, and the single recording of the data along a single pinhole confocal microscope, i. It leads to the conclusion that it works better than one-dimensional parallel recording of data in a focus microscope.

[0021] Consideration of statistical accuracy as measured by the S / N ratio is important for systems such as slit confocal microscopes over standard microscopes or single pinhole confocal microscopes over slit confocal microscopes. When affecting the selection, the remaining signal from the out-of-focus image for the selected system may be compared to or larger than the in-focus signal. Such cases include, for example, examining deep within biological samples at optical wavelengths where scattering of optical radiation is dominant over absorption. In this case, there remains a need for computer-deconvolution which is very long, i.e. longer than the time required to acquire the data. This is generally true for a single pinhole confocal microscope as well as a slit confocal microscope when looking for a focused image signal that is much smaller than the rest of the out-of-focus image signal.

Although it is easier to accurately digitize the signal from the CCD detector than the signal from the PMT (Scanning 1994, 13: 184-198, J.B.
"Radical and practical limitations in confocal light microscopy" by Parlay), the PMT is a single device that can be characterized with high accuracy, while the CCD actually consists of separate detectors Correction operations for pixel-to-pixel variations in sensitivity and offset that characterize the behavior of large arrays involve additional noise (
Y. Hiraoka et al., Supra; Methods Cell Biol. 1989, 29, pp. 239-267. E. FIG. Wampler and K. "Quantitative Fluorescence Microscopy Using a Photomultiplier Tube and an Image Detector" by Kutz; Methods Cell Biol. 1989 30, pp. 47-83; Weeze, J.M. Brian and L.M. C. "Validity of imaging systems: steps to evaluate and validate microscopic imaging systems for quantitative studies" by Smith).

It should be noted that the above discrimination between the photodetectors used in the two methods of the three-dimensional microscope should not be considered complete. Because cooled CCD detectors are the most suitable photodetectors for their confocal microscopes, which achieve the scanning function by using the holes of a rotating disk (cited above, such as Petran; Quoted above).

“Another technique, known as optical coherence-domain reflectometry (OCDR), has been used to obtain information about the three-dimensional properties of the system. (1) Opt. Lett.
Year 12 (3), pp. 158-160 C. Young Quest, S.M. "Optical Coherence-Domain Reflector: New Optical Evaluation Technology" by Kerr and DEN Davis
(2) Appl. Opt. 1987, 26 (9), pp. 1603 to 1606; Takada, I. Yokohama, K.K. Ciba and J.M. Noda, "New measurement system for misplacement in optical waveguides based on interferometer technology"; (3) Appl. Opt. 1987 26 (14) 28
Pages 36 to 2842 B. L. Danielson and C.I. D. "Guided-Wave Reflectometry with micrometer resolution" by Wittenberg
The OCDR method is a coherent optical time-domain reflectometer (OTDR) technique in that a pulsed light source is replaced by a broadband continuous wave light source with a short coherence length. Is different. The source beam enters the interferometer, one arm having a movable mirror, the light reflected from the mirror providing the reference beam, and the other arm encompassing the optical system being tested. Interference signals in the light coherently mixed and reflected from the two arms are detected by conventional heterodyne techniques and provide the desired information about the optical system.

Heterodyne detection of backscattered signals in OCDR technology is achieved by a method of “white light interferometry, in which the beam is split into two arms of an interferometer and is adjustable. Reflected by the mirror and the backscattering site and recombined coherently, the interference fringes are recombined only when the difference in optical path length between the two arms is less than the coherence length of the beam. (1) and (1).
The OCDR system described in 3) uses this principle and reference (3)
Fig. 3 shows Interferograms of fiber gaps in a test system, obtained by scanning an adjustable mirror and measuring the strength of the recombined signal. Reference (1) discloses that the mirror of the reference arm oscillates at a controlled frequency and amplitude to cause a Doppler shift in the reference signal, and the recombined signal is provided to a filtering circuit to detect the beat frequency signal. It also describes the modified method.

Another variation of this technique is shown in reference (2) where the reference arm mirror is in a fixed position and the difference in optical path length of the two arms exceeds the coherent length. I have. The combined signal is then introduced into a second Michelson interferometer with two mirrors, one fixed in position and the other movable. The movable mirror is scanned and the difference in path length between the arms of the second interferometer causes the delay between the backscattered signal and the reference signal at each position of the movable mirror corresponding to the scattered site. To compensate. In practice, a phase change that oscillates at a constant frequency is imposed on the signal from the site that is backscattered by means of a piezoelectric conversion modulator in the fiber leading to this site. The output signal from the second Michelson interferometer is provided to an internally located amplifier that detects a beat frequency signal resulting from both the piezoelectric conversion modulation and the Doppler shift caused by the movement of the scanning mirror. I do. This technique has been used to measure the irregularity of glass wave guides with resolutions as short as 15 μm.
[Opt. Lett. No. 14 (13), pp. 706-708 (1989) Takada, N.M. Takato, J.C. Noda and Y. Noguchi, "Characterization of silica-based wave guides with an interferometric optical time-domain reflectometer system using 1.3 μm wavelength superluminescent diodes"].

Another variation of the OCDR is a dual beam partial coherence interferometer (PCI) that has been used to measure fundus layer thickness [Opt. Eng. 34 (3)
No. 701-710 (1995) Drexer, C.I. K. Hitzenberger, H.E.
Satman and A.S. F. "Measurement of fundus layer thickness by partial coherence tomography" by Farcher]. In the PCI used by Drexer et al., An external Michelson interferometer emits a light beam of high spatial coherence but very short coherence length of 15 μm with reference beam (1) and measurement beam (2).
Into two parts. At the exit of the interferometer, the two components are recombined to form a coaxial double beam. The two beam components have a path difference of twice the difference in interferometer arm length, illuminate the eye and reflect off some interfaces present inside the eye to separate media of different refractive indices . Thus, each beam component (1 and 2) is decomposed into further components by reflection at these interfaces. The reflected subordinate components are superimposed on the photodetector. If the optical distance between the two boundaries inside the eye is equal to twice the difference in interferometer arm length, there are two sub-components that will run over the same full path length and will therefore interfere I do. Each value of the interference arm length difference where the interference pattern is observed is equal to the optical distance inside the eye. In the absence of other strong reflections in the immediate vicinity, the absolute position of these interfaces can be determined in vivo with an accuracy of 5 μm. However, PCI is subject to object motion during the time required for a three-dimensional scan,
Subject to restrictions.

Another version of OCDR, called Optical Coherent Tomography (OCT), is described in Opt. Lett. 18 (21) 1864-1866 (1993). A. Swanson, J.M. A. Isat, M.S. R. Hey, D. Huang, C.I. P. Lin, J
. S. Schumann, C.I. A. Puriaphyto and J.M. G. FIG. "Optical coherence tomography imaging in the retina" by Fujimoto and E. U.S. Pat. No. 5,321,501, issued Jun. 14, 1994. A. Swanson,
D. Huang, J.M. G. FIG. Fujimoto, C.I. A. Puriaphyto, C.I. P. Rin,
And J. S. "Methods and apparatus for imaging optical images by means of controlling the longitudinal extent of a sample" by Schumann, has been reported for in vivo retina imaging. The above referenced patent describes a method and apparatus for performing imaging of an optical image on a sample, wherein longitudinal scanning or positioning in the sample is performed on the sample and on the reference reflection. It is provided either by changing the relative optical path length for the optical path leading to the mirror, or by changing the optical properties of the output from the light source applied to the device. One or two-dimensional transverse scanning may provide controlled relative movement between the sample and the probe module in such a direction and / or direct the optical radiation of the probe module to a selected transverse position. Provided on the sample by. The reported spatial resolution is less than 20 μm with high sensitivity (100 dB dynamic range). However, OTC suffers from subject motion limitations during the time required for a three-dimensional scan.

[0029] Observation recorders of optical interferometers are widely used for the extraction of three-dimensional contours of surfaces when a non-contact layer method is required. These observation recorders typically use phase-shifting interferometer (PSI) technology and are fast, accurate, and reproducible, but have a smooth surface compared to the intermediate wavelength of the light source. Is requested. Surface discontinuities greater than 1/4 wavelength (typically 150 nm) cannot be resolved unambiguously in single wavelength measurements due to the periodic nature of the interference. Multi-wavelength measurements can extend this range, but the constraints imposed on wavelength accuracy and environmental stability can be severe (see the title "Optical system for terrain surface measurement", N
. US Patent No. issued July 20, 1982 to Barras Bramanian
. No. 4,340,306) Observation recorders based on interferometry (SWLI) scanning with white light overcome many of the limitations of conventional PSI observation recorders for measuring rough, discontinuous surfaces. Many papers have described this technique in detail (Appl. Opt. 33)
No. (31), pp. 7334-7338 (1994). Deck and P.E. Da
See references 2-7 in Groot). Typically, these observation recorders provide a contrast reference feature for each point in the field of view (ie, while relaying on-axis one arm of an equal-path interferometer illuminated by a broadband light source). Record the position of peak contrast or peak fit. A common problem with this technique is the enormous amount of computation required to compute the contrast at each point in real time. Often, only the contrast operation becomes inaccurate due to the individual sampling intervals, forcing either to increase the sampling density or to introduce interpolation techniques. Both of these techniques make the data acquisition process even slower. A coherence probe microscope (CPM) is an example of this class of observation and recording equipment means (titled "Methods and Apparatus for Using a Two-Beam Interferometric Microscope for Integrated Circuits and Other Inspections"). U.S. Patent No. 4,818,110, issued April 4, 1989.
No. SPIE 775, pages 233 to 247 (1987). Davidson, K.C. Kauffman,
I. Maser and F.S. Cohen, entitled "Application of Interference Microscopy to Integrated Circuit Inspection and Metrology";"Image Enhancement Method for Coherence Probe Microscope with Application to Integrated Circuit Metrology". Davidson, K.C. Kaufman and I.S. U.S. Pat. 5,1
12, 129). In general, observation recorder means, especially CPM, cannot work with three-dimensional objects, have the background typical of conventional interference microscopes, are sensitive to fluctuations, and require powerful computer analysis.

Observation recorders based on triangulation also overcome many of the limitations of conventional PSI observation recorders, but have the disadvantage of reduced height and lateral space resolution and large background shapes outside the image. is there. This technology is applied in “Applied Optics” published in 1993.
(35), pages 7164-7169. Heusler and D.W. It can be found in a paper by Ritter entitled "Parallel 3D Detection by Color Coded Triangulation". The method used by Heusler and Ritter in the same area is based on the following principle: The color spectrum of a white light source is imaged on an object by illuminating it from a certain direction. The object is observed by the color TV camera from an observation direction different from the irradiation direction. The color (hue) of each pixel is a unit of measure for distance from the reference plane. This distance depends on the charge coupled device (CC
D) It can be evaluated by the three (red-green-blue) output channels of the camera, and this evaluation can be performed in real time of the TV. However, the resolution of the height and some lateral spatial dimensions is significantly lower than that possible using PSI and SWLT, and with a large background, the triangulation observation recorder has the noise characteristics of interferometerless measurement techniques. Have. Furthermore, triangulation observation recorders are limited to surface observation records.

One of the problems encountered with white light interferometry (WLI) is phase ambiguity. Observation recorder method paying attention to phase ambiguity is described in Opt. Lett. 19 (13), 995-9
"Dispersive Interferome Observation Recorder (Dispersive Interferome)
tric Profilometer). Schweider and L.W. It is a distributed interferometer observation recorder (DIP) proposed by Elephant. A similar approach to WLI is described in Pure Appl. Opt. 4, pp. 643-651 (1995).
In the article entitled "Absolute Distance Measurement Using Synchronously Sampled White Light Frequency Band Spectrum Interferometer". Schnell, E. Zimmerman and R.A. Also reported by Dendlinker.

In general, the problem of phase ambiguity can be completely avoided using DIP. In a DIP device, a collimated beam of a white light source impinges vertically on the real wedge of a Fizeau interferometer in front of the objective of an apochromat microscope. The Fizeau interferometer is formed by the inner surface of the reference plate and the surface of the object. Next, the light is backscattered onto the slit of the grating spectrometer. The grating spectrometer disperses the invisible fringe pattern of the sofa and projects its spectrum onto a linear array detector. On the detector, each point on the surface selected by the slit in the spectrometer gives a dispersed spectrum of the air gap in the Fizeau interferometer. The fringe pattern can be evaluated numerically by using a Fourier transform and a filtering method to obtain phase information from the intensity distribution of the wedge type interferogram.

Although the problem of phase ambiguity can be avoided with the use of DIP, DIP is not suitable for applications requiring inspection of three-dimensional objects. This is because D from the out-of-focus image
This is the result of the relatively large intrinsic background generated by IP. This background problem can be compared to the background problem encountered when trying to generate a three-dimensional image using a standard interference microscope.

An apparatus and method for spectrally resolving light that is reflected, emitted or scattered from a sample is described in E. FIG. Dickson, S.M. Damaskinos and J.M. W. Bauron, 19
No. 5,192,980, issued March 9, 1993, entitled "Apparatus and Method for Spatial and Spectral Decomposition". In a series of examples of the Dickson et al device and method, the properties of the sample are characterized in terms of the intensity of light reflected, emitted or scattered from the sample, and the device and method are of the non-interfering and non-confocal type. , Use dispersive elements before the detector. The series of examples of Dickson et al. Are of the non-confocal type because they have a large background from out-of-focus images inherent in standard microscopes.

The devices and methods of Dickson et al. Further include non-coherent confocal embodiments that allow measurements with low background. However, the constraints on intensity measurements of confocal and non-confocal embodiments resulting from the use of non-interfering techniques place significant constraints on information about the sample obtained from reflected or scattered light. In the intensity measurement, information about the square of the magnitude of the reflected or scattered light of the sample is generated, but information about the phase of the magnitude of the reflected or scattered light is lost. The Fourier transform spectrometer embodiment of Dickson et al. Has the disadvantage that there is a large background from out-of-focus images inherent in non-confocal imaging systems.

An apparatus for measuring multiple wavelengths simultaneously using a non-coherent confocal imaging system includes:
G. FIG. Kusiao disclosed in U.S. Pat. No. 5,537,247, issued Jun. 1996, entitled "Single Aperture Confocal Imaging System". Kusiao's device is a confocal scanning imaging system that uses only one device for both incident light from the light source and reflected light from the object, as well as selectively reflecting different wavelengths of reflected light to a series of detectors, respectively. It consists of a series of directing beam splitters and optical wavelength filters.
The Xuiao device has the advantage of making measurements at different wavelengths simultaneously and the advantage of a confocal imaging system with less background from out-of-focus images. However, the limitations on intensity measurements that result from using non-interfering techniques place significant constraints on the information about the sample obtained from reflected or scattered light. In the intensity measurement, information about the square of the magnitude of the reflected or scattered light of the sample is generated, but information about the phase of the magnitude of the reflected or scattered light is lost.

G. O. Kusiao, T .; R. Cole and G.C. S. Kino used white light for the confocal microscope in a paper entitled "Real-time confocal scanning optical microscope" described in the 1988 Applied Physics Report, No. 53 (8), pp. 716-718. He points out that due to the chromatic aberration of the objective lens, there are all images from different heights in the sample, all in focus, but with different colors. Kusiao et al. Demonstrated this view by generating images of silicon integrated circuits at four different wavelengths. H. J. Tiziani and H.S. M. Ude et al. Published a paper entitled "3D Image Detection by Color Confocal Microscope" in "Applied Optics", No. 33 (10), pp. 1838-1843, published in 1994. It describes a white light, non-coherent confocal microscope in which chromatic aberration is intentionally incorporated into the objective lens of the microscope to obtain height information. A camera using black and white film uses the selected three color filters to sequentially combine the color intensity and tone of each object point. Confocal microscopy was used in both the studies described by Kusiao et al. And Tiziani and Uude, which reduced background from out-of-focus images, but were limited to making intensity measurements. The limitations in making intensity measurements that are a direct consequence of using non-interfering techniques are those that limit the information about the sample obtained from reflected or scattered light, as described with respect to the Dixon et al. And Kusiao patents. give.

As for the interference microscope, “Applied Optics”, No. 26 (26),
G. pp. 775-3783. S. Kino and S.M. C. Chim's paper entitled "Mirau Correlation Microscope" and "Applied Optics" 31 (14), 2550
Page 2553 S. C. Chim and G.C. S. It is described in Keno's paper entitled "Realization of Three-Dimensional Images in Interferometric Microscopy", the latter being based on the Mirau interferometer configuration. The Kino and Chim instruments use an interference non-confocal microscope that includes a spatially and temporarily incoherent light source to detect the correlation signal between the beam reflected from the object and the beam reflected from the mirror, respectively. Use as output. Using the Kino and Chim devices, both the amplitude and phase of the beam reflected from the object can be measured. However, the Kino and Chim interferometers suffer from a significant background problem: the background level from out-of-focus images is the level commonly found in standard interferometric non-confocal microscope systems.

Regarding the interference device, A.I. U.S. Pat. No. 5,897,098 issued to Knuttel on Oct. 15, 1996, entitled "Imaging by Static Optical Spectroscopy in a Cloudy Object by Special Light Focusing and Signal Detection of Light with Various Light Wavelengths". 5,565
, 986, describe a method of acquiring a spectral image of an object and displaying both lateral spatial resolution and depth field of view. The apparatus described by Knuttel has a non-confocal imaging system and generally includes dispersive optics in an arm of an interferometer;
A colored objective lens. Dispersive elements can record information about the amplitude of scattered light at different light wavelengths, and by using an interferometer, can record information about the amplitude of reflected or scattered light and the phase of the amplitude. By using a colored objective lens, information on the visual field in the depth direction can be recorded. However, Knuttel's interferometer has a significant background problem, namely, the background level is the level commonly found in standard interferometric non-confocal microscope systems.

One of the main objectives of the Knuttel apparatus embodiment is that by using two different grades of colored objectives contained in a portion of the zone plate, two objects of the depth dimension separated. Regions could be imaged simultaneously. As a result, the signal recorded by the detector of this embodiment consists of superimposed images from two separate depth positions in the object. Therefore, in addition to the presence of the high-level background from the out-of-focus image as described above, a complicated inversion calculation is performed by a computer to extract an image at a specific depth from the superimposed in-focus image. Significant problems have arisen in the form of inversion calculations required for the superimposed images acquired in the Knuttel reference example. That is, the result of the inversion calculation is relatively accurate near the surface of interest, but deteriorates rapidly as the sample depth increases. The problem is that in the reversal calculation, where only one point of interest is in the focus of the detector,
Generally does not occur.

The above background problem that arises with interference microscopes is discussed in “Optica,” published in 1982.
Acta ", No. 29 (12), pp. 1573-1577. K. Hamilton and C.I. J. R. It is reduced by an interferometric confocal microscope as seen in the article entitled "Confocal Interferometric Microscope" described by Shepard. The system is based on a confocal microscope in which the object is scanned for a focused laser spot and the laser spot is positioned so as to match the background image of the point detector. The interferometric form of a reflection confocal microscope is based on a Michelson interferometer where one beam is focused on an object. This system has the important property of reduced background from out-of-focus images inherent in confocal microscope systems. However, the confocal interference microscope of Hamilton and Shepard described in the same place
Measure only one reflected signal at a time in the dimensional object. By scanning one point of interest at a time, the system is also more sensitive to sample movements that are unrelated to the scan in acquiring the required data.

A key factor in the effective use of high performance computers is memory. Such equipment requires a huge data storage device, and therefore requires a small, low-cost, very high-capacity, high-speed memory element to process a large amount of data provided by parallel computing.

In the case of a two-dimensional memory, the theoretical maximum storage density (proportional to 1 / λ ² ) is λ = 53
At 2 nm, it is 3.5 × 10 ⁸ bits / cm ² , and in the case of a three-dimensional memory, it is 6.5.
× 10 ¹² bits / cm ³ . These maximum values represent the upper limit of storage capacity when 1-bit binary format is used in each storage location. These upper limits can be increased using recording media that records different levels of amplitude information or amplitude and phase information. Holographic recording on a phase recording medium is an example of the latter mode.

In the recording of the different modes, the 1-bit binary mode, the amplitude of the base N format and the phase of the (base N) × (base M) format at each storage location, the voxels of the available storage locations and thus the storage density are: It is limited by the S / N ratio that can be obtained, which is almost inversely proportional to the voxel capacity. In particular, in the case of amplitude recording mode or amplitude and phase recording mode, the number of individual pieces of information that can be stored in a voxel is also limited by the S / N ratio that can be obtained.

What is needed is that the sensitivity of the image data to out-of-focus images be reduced to less than the sensitivity inherent in prior art confocal and confocal interference microscopes;
The sensitivity of the image data is reduced with respect to both systematic and statistical errors,
Reduced requirements for computer deconvolution in connection with reduced sensitivity to out-of-focus images, the potential for high signal-to-noise ratio inherent in confocal interference microscopy systems, and the ability to record axial or transverse data in parallel And the possibility to measure the complex amplitude of the scattered and / or reflected light beam.

[0046]

[Problems to be solved by the invention]

Therefore, an object of the present invention is to provide a method and an apparatus for reading information from positions at different depths in an optical disc.

It is an object of the present invention to provide a method and apparatus for reading information from a plurality of depth positions on an optical disc. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for simultaneously reading information from a plurality of depth positions in an optical disc.

It is an object of the present invention to provide a method and apparatus for reading information from a plurality of tracks on or on an optical disc. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for simultaneously reading information from a plurality of tracks on or in an optical disc.

It is an object of the present invention to provide a method and apparatus for simultaneously reading information from a plurality of tracks and positions on a plurality of tracks on or in an optical disk. An object of the present invention is to provide a method and apparatus for simultaneously reading information from a plurality of depths and a plurality of tracks in an optical disc.

An object of the present invention is to provide a method and an apparatus for writing information at a plurality of depth positions in an optical disc. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for writing information simultaneously at a plurality of depths in an optical disc.

It is an object of the present invention to provide a method and apparatus for writing information on an optical disk or at a plurality of tracks on an optical disk. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and an apparatus for simultaneously writing information on a plurality of tracks on or in an optical disc.

It is an object of the present invention to simultaneously write information at a plurality of depths and a plurality of track positions on an optical disc. It is an object of the present invention to provide a method and apparatus for writing information at a plurality of depths in a relatively high density optical disc.

It is an object of the present invention to provide a method and apparatus for writing information simultaneously at a plurality of depth positions in a relatively high-density optical disc. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for writing information at a plurality of tracks on or within a relatively high density optical disc.

It is an object of the present invention to provide a method and apparatus for writing information at a plurality of tracks simultaneously on or on a relatively high-density optical disc. SUMMARY OF THE INVENTION It is an object of the present invention to provide a method and apparatus for simultaneously writing data at a plurality of depths and a plurality of tracks in a relatively high-density optical disc.

An object of the present invention is to provide a one-dimensional, two-dimensional and three-dimensional, complex-amplitude tomographic imaging method of complex amplitude, which is quick and reliable. SUMMARY OF THE INVENTION It is an object of the present invention to improve complex amplitude tomographic imaging techniques in order to avoid the disadvantages of the prior art.

It is another object of the present invention to provide a complex amplitude tomographic imaging technique that advantageously reduces or eliminates the effects of statistical errors in light from out-of-focus image points.

Another object of the present invention is to improve a complex amplitude tomographic imaging technique in which the effects of systematic errors in out-of-focus light images are significantly reduced or eliminated. It is another object of the present invention to provide a complex amplitude tomographic imaging technique that allows an image of an object to be formed at a plurality of image points substantially simultaneously.

Another object of the present invention is to perform one-dimensional, two-dimensional and three-dimensional complex amplitude tomographic imaging using means for obtaining an S / N to image achievable with an interferometric system. It is to provide a convenient technology.

It is another object of the present invention to provide a complex amplitude tomographic imaging system and technique that avoids the computational difficulties of solving a nonlinear differential equation. It is another object of the present invention to provide a technique that is advantageous for complex amplitude tomography of a line portion or a two-dimensional portion within an object, regardless of the motion of the object.

[0060]

[Means for Solving the Problems]

The embodiments and modifications thereof described below are classified into five types of embodiment groups as follows. A particular one of the first group of embodiments and its variants is that the one-dimensional image information is generated by a corresponding one of the second group of embodiments and its variants in which the background reduction and compensation are obtained simultaneously. A one-dimensional image substantially orthogonal to the one-dimensional image to be generated is generated. A particular one of the other embodiments of the first group of embodiments is that the information of the two-dimensional image is generated by a corresponding one of the second group of embodiments and its variants wherein the information is obtained simultaneously with the background reduction and compensation. A two-dimensional image substantially orthogonal to the two-dimensional image to be generated is generated.

One particular example of the third group of embodiments and variations thereof is the fourth group of embodiments and variations thereof in which the information of the one-dimensional image is not obtained at the same time as performing background reduction and compensation. Generate a one-dimensional image substantially orthogonal to the one-dimensional image generated by the corresponding one of A particular one of the third embodiment and its variants is substantially orthogonal to the corresponding one of the fourth embodiment and its variants where the information of the two-dimensional image is not obtained at the same time as the background reduction and compensation. A two-dimensional image is generated.

The fifth group of embodiments and variations thereof generate a multidimensional image as a sequence of single point images obtained by background reduction and compensation. Briefly, the present invention distinguishes between the complex amplitude of the in-focus image and the complex amplitude of the out-of-focus image by focusing light rays from a broadband and spatially incoherent point light source to the light source pinhole. A method and apparatus according to a first group of embodiments. Light rays emanating from the light source pinhole are collimated and directed to the first phase shifter. The phase of the first portion of the collimated beam is shifted by a phase shifter to produce a first amount of the phase-shifted beam;
The phase of the second portion of the collimated beam is shifted by a phase shifter to produce a second amount of the phase-shifted beam. The first and second amounts of the phase shifted light beams are focused on a first spot.

[0063] A first amount of the phase shifted light rays emanating from the first spot are collimated and directed to the beam splitter. The first of the collimated rays
The portion passes through the beam splitter to form a first amount of the probe beam, and a second portion of the collimated light beam is reflected by the beam splitter to form a first amount of the reference beam. A second amount of rays diverging from the first spot and phase shifted are collimated and directed to the beam splitter. A first portion of the collimated light beam passes through the beam splitter to form a second amount of the probe beam, and a second portion of the collimated light beam is reflected by the beam splitter to form a second amount of the reference beam. To form

The first and second amounts of light of the probe beam are directed toward a second phase shifter. A first amount of the beam of the probe beam is phase shifted to form a third amount of the probe beam, and a second amount of the beam of the probe beam is phase shifted to form the fourth amount of the probe beam. However, the amount of net phase shift generated by the first and second phase shifters for the third and fourth amounts of the probe beam is the same. The third and fourth amounts of the probe beam are focused by the first probe lens to form a line image in the target material and illuminate the target material. The line image is closely aligned along the optical axis of the first probe lens, the length of the line image along the optical axis is adjustable, the depth of focus and chromatic aberration of the first probe lens, and the light source It depends on a combination of factors such as optical bandwidth.

The first and second amounts of the reference beam are directed to a third phase shifter. A first amount of the reference beam is phase shifted to form a third amount of the reference beam, and a second amount of the reference beam is formed to form a fourth amount of the reference beam. Phase shifted. Here, for the third and fourth amounts of the reference beam, the net phase shift generated by the first and third phase shifters is the same. The third and fourth amounts of the reference beam are focused by the reference lens onto the spot of the reference mirror.

Of the probe beams diverged from the irradiation target toward the probe lens,
The reflected or scattered light corresponding to the third and fourth quantities forms a scattered probe beam, which is collimated by a probe lens and directed to a second phase shifter. A phase shift is performed on a first portion of the collimated light beam, and after the shift,
The formed light beam becomes the first amount of the scattering probe beam after the phase shift. Further, a phase shift is performed on a second portion of the collimated light beam, and this is the second amount of the scattering probe beam after the phase shift. The first and second quantities of the scattered probe beam are directed to a beam splitter. Where the scattered probe beam
Some of the first and second quantities are each reflected by the beam splitter,
After the phase shift, a third quantity and a fourth quantity of the scattering probe beam are formed. Thereafter, the third and fourth amounts of the parallel rays of the scattered probe beam are focused by the spatial filter lens at the spatial filter pinhole.

The reflected light emitted from the spot on the reference mirror to the reference lens forms a reflected reference beam, which is collimated by the reference lens and directed to the third phase shifter. The first portion of the collimated reflected light beam is phase-shifted, and the light beam formed here is referred to as the first amount of the phase-shifted reflected reference beam first. Further, a phase shift is performed on the second portion of the collimated reflected light, and this is the second amount of the reflected reference beam after the phase shift. The first and second amounts of rays of the reflected reference beam are directed to a beam splitter. First of the reflected reference beam
A portion of the quantity and the second quantity are respectively sent by the beam splitter to form a third quantity and a fourth quantity of the reflected reference beam. After this, the third and fourth quantities of the reflected reference beam
A quantity of collimated rays is focused by a spatial filter lens onto a spatial filter pinhole.

A part of the third amount of the scattered probe beam and a part of the fourth amount are respectively passed through the spatial filter pinhole and then subjected to the spatially filtered scattered probe beam third amount and the spatially filtered scattered probe beam, respectively. Forming a fourth quantity of the scattered probe beam.
Both the third and fourth quantities of the spatially filtered scattered probe beam are collimated by the dispersive element lens and directed to the dispersive element.
In this case, it is desirable to use a reflection type diffraction grating as the dispersion element.

A part of the third quantity of the reflected reference beam and a part of the fourth quantity respectively pass through the spatial filter pinhole and then are respectively subjected to the spatially filtered reflected reference beam third quantity.
The quantity forms a fourth quantity of the spatially filtered reflected reference beam. Both the third and fourth quantities of the spatially filtered reflected reference beam are collimated by a dispersive element lens and directed to the dispersive element.

The third quantity of the spatially filtered scattered probe beam emanating from the dispersive element and the fourth quantity of the spatially filtered scattered probe beam both pass partially through the detector lens, A processed and spatially filtered scattered probe beam third quantity and a wavenumber filtered and spatially filtered scattered probe beam fourth quantity. The third and fourth quantities of this wavenumber filtered and spatially filtered scattered probe beam are focused by a detector lens and form a line image on a plane where a plurality of detector pinholes are linearly arranged. Form. Also, both the third spatially filtered reflected reference beam and the fourth spatially filtered reflected reference beam emanating from the dispersive element partially pass through the detector lens and are each wavenumber filtered. A spatially filtered reflected reference beam third quantity and a wave number filtered spatially filtered reflected reference beam fourth quantity are obtained. The wavenumber-filtered and spatially filtered reflected reference beam third and fourth quantities are focused by a detector lens, and the plurality of detector pinholes are linearly arranged on a plane where the reflected reference beam is reflected. A line image is formed by the third and fourth amounts.

The third and fourth quantities of the wavenumber-filtered and spatially-filtered scattered probe beam and the third and fourth quantities of the wavenumber-filtered and spatially-filtered reflected reference beam were partially overlapped. Transmitted in the form of a detector pinhole, the intensity of which is measured by a multi-pixel detector. A plurality of pixels are linearly arranged in the multi-pixel detector, and a value measured by the detector becomes a first array of measured intensity values. In addition, the phases of the third and fourth amounts of the wave number-filtered and spatially-filtered reflected reference beam are shifted using radians by a fourth phase shifter, and the first and second phase-shifted wave numbers are filtered and spatially filtered. The third and fourth quantities of the reflected reference beam are formed. This is followed by a wavenumber filtered and spatially filtered scattered probe beam.
The third and fourth quantities, and the wavenumber-filtered and spatially filtered reflected reference beam after the first phase shift, the third and fourth quantities are transferred by the detector pinhole in a partially overlapping fashion and overlap The intensity of the transmitted portion is measured by a multi-pixel detector. The value measured here is the second array of measured intensity values.

The wave number-filtered and spatially filtered reflected reference beam third
The phases of the quantity and the fourth quantity are again shifted using radians by the fourth phase shifter to form third and fourth quantities of the wavenumber-filtered and spatially filtered reflected reference beam after the second phase shift, respectively. You. Thereafter, the wavefront-filtered and spatially filtered scattered probe beam third and fourth quantities and the second phase-shifted wavenumber-filtered and spatially filtered reflected reference beam
The third and fourth quantities are transferred by the detector pinholes in a partially overlapping manner, and the intensity of the overlapping sections is measured by a multi-pixel detector. The value measured here becomes the third array of measured intensity values.

Similarly, the phases of the third and fourth quantities of the reflected reference beam, which are further subjected to wave number filtering and spatial filtering, are again shifted using radians by the fourth phase shifter, and the third phase shifted wave number filter The processed and spatially filtered reflected reference beam third and fourth quantities are formed, respectively. After this, the third and fourth quantities of the wavenumber-filtered and spatially filtered scattered probe beam and the third and fourth quantities of the wavenumber-filtered and spatially filtered reflected reference beam after the third phase shift are partially The intensity of the portion transmitted by the detector pinhole in an overlapping manner and transmitted in an overlapping manner is measured by the multi-pixel detector. The value measured here becomes the fourth array of measured intensity values.

In the next step, the first, second, third and fourth arrays of measured intensity values are sent to a computer for processing. The computer subtracts the corresponding elements of the second array of measured intensity values from the elements of the first array of measured intensity values to calculate a first array of component values that are the measured values. This first array of component values represents the complex amplitude of the scattered probe beam focused on the plane of the detector pinhole, and the effects of light rays due to out-of-focus images are largely eliminated. Similarly, the computer subtracts the corresponding element of the fourth array of measured intensity values from the element of the third array of measured intensity values, and this measurement is referred to as the second component value.
It becomes an array. The second array of component values represents the complex amplitude of the scattered probe beam focused on the plane of the detector pinhole and the effects of light rays due to out-of-focus images are largely eliminated.

The first array of component values and the second array of component values, which indicate the complex amplitude of the scattered probe beam, are orthogonal component values, and are therefore focused on the plane of the detector pinhole, and the effect of light rays due to out-of-focus images Figure 4 shows an accurate measurement of the complex amplitude of the scattered probe beam, where is greatly excluded, within complex constants. By using a computer or a computer algorithm known in the art, an accurate one-dimensional representation can be obtained for a straight line portion of the target material without scanning the target material. This is because the direction of the linear portion matches the direction of the optical axis of the probe lens.
That is, this process is possible because the straight section typically passes through one or more surfaces of the subject material, or the single surface itself forms a straight line. Similarly, by using a computer or a computer algorithm known in the art, the two-dimensional and three-dimensional representations of the target material can be accurately obtained based on the two-dimensional array and the three-dimensional array, respectively. In this case, the two-dimensional array is
The first, second, third and fourth arrays of the measured intensity values obtained by scanning in two dimensions, the three-dimensional array is the first and second of the measured intensity values obtained by scanning the target material in two dimensions. It consists of a second, third and fourth array. In addition to the straight portions of the material of interest, the flat portions and the volume portions are also present, usually passing through or being taken up by one or more surfaces. Scanning these parts is accomplished by systematically moving the target material in one and two dimensions using a computer controlled translator. In this case, as a computer algorithm, a deconvolution or an integer equality inversion method which is currently known in the art may be used. The amplitude component value of the scattering probe beam
Although the out-of-focus image has already been corrected in the first and second arrays, further correction can be performed by using a deconvolution method or the like.

Next, a second embodiment will be described. This second embodiment is a method and apparatus for identifying the complex amplitude of an in-focus image and the complex amplitude of an out-of-focus image, the method being broadband, spatially extended, and spatially incoherent. In this method, imaging is performed on a linear array of light source pinholes based on optical radiation from a linear light source having certain characteristics. In this second embodiment, the apparatus and the electronic processing method are different from those of the first embodiment. That is, a linear array of light source pinholes is used instead of the light source pinholes of the first embodiment. Also, a linear array of spatial filter pinholes is used instead of the spatial filter pinholes of the first embodiment, and a two-dimensional array is used instead of the linear array of detector pinholes and multi-pixel detectors of the first embodiment. Use a multi-pixel detector with a detector pinhole and a two-dimensional array of pixels. The directions of both the linear array light source pinholes and the linear array spatial filter pinholes are perpendicular to the plane defined by the dispersive elements. Both the two-dimensional array of detector pinholes and the two-dimensional array of multi-pixel detectors are oriented at the image of a linear array of light source pinholes created at the focal plane of the multi-pixel detector. ing.

The first and second component values of the amplitude of the wavenumber filtered and spatially filtered scattered probe beam are based on the fact that the elements of the measurement array are quadrature component values and therefore the detection of a two-dimensional linear array. It provides an accurate measurement of the complex amplitude of the scattered probe beam within the complex constants, focused on the plane of the detector pinhole and greatly eliminating the effects of light rays due to out-of-focus images. Using computer algorithms now known in the art, an accurate two-dimensional representation of the two-dimensional portion of the target material can often be obtained without scanning the target material. This is because the two-dimensional portion is selected based on the direction of the linear array of light source pinholes and the direction of the optical axis of the probe lens. That is, this process is possible because the two-dimensional portion typically passes through one or more surfaces of the target material, or the single surface itself forms the two-dimensional portion. Also, by using computer algorithms currently known in the art, the three-dimensional representation of the target material can be obtained by scanning the target mainly in one dimension and obtaining the first, second, third, and fourth Intensity value 3
Accurately acquired using a dimensional array. This is because the three-dimensional representation of the target material is typically a representation of one or more surfaces of the target material. In this case, as a computer algorithm, a deconvolution or an integer equality inversion method which is currently known in the art may be used. The out-of-focus image has already been corrected in the first and second arrays of the component values of the amplitude of the scattered probe beam according to the present invention, but can be further corrected by using a deconvolution technique or the like.

Next, a modification of the second embodiment will be described. This variation is a method and apparatus for distinguishing in-focus and out-of-focus images, the method comprising a broadband, spatially extended and spatially incoherent line source. This is to image the light source slit based on the optical radiation.
In this modification, an apparatus and an electronic processing method different from those of the second embodiment are used. That is, a light source slit is used instead of the light source pinhole of the linear array of the second embodiment. Also, a spatial filter slit is used instead of the linear array spatial filter pinhole of the second embodiment. The directions of the light source slit and the spatial filter slit are both perpendicular to the plane defined by the dispersive element.

The first component value and the second component value of the amplitude of the scattered probe beam subjected to the wave number filtering process and the spatial filtering process, the elements of the measurement array are orthogonal component values. By its nature, the complex amplitude of a wavenumber-filtered spatially filtered scattered probe beam that is focused on the plane of the detector pinhole in a two-dimensional array, while greatly eliminating the effects of light rays due to out-of-focus images Shows an accurate measurement value within the range of the complex constant. Using computer algorithms known in the art, an accurate two-dimensional representation of the two-dimensional portion of the target material can be obtained without having to scan the target material. This is because the two-dimensional part is selected based on the direction of the light source slit and the direction of the optical axis of the probe lens. Also, using a computer algorithm known in the art, the three-dimensional representation of the target material is obtained by scanning the target in one dimension and obtaining the first, second, third, and fourth intensity values obtained therefrom. Is accurately obtained using a three-dimensional array of. Scanning of the target material is accomplished by systematically moving the target material in one dimension using a translator controlled by a computer. in this case,
As the computer algorithm, a deconvolution or an integer equation inversion method which is currently known in the art may be used. Although the out-of-focus image is also corrected by the apparatus of the present invention, the correction can be further performed by using a deconvolution method or the like.

In the first and second embodiments described above, it is also possible to improve or optimize the S / N ratio, or both. This can be achieved by using additional optical techniques, and the electronic processing techniques used are approximately the same as for the devices of the first and second embodiments of the present invention. An additional optical approach is to modify the path of the reference and probe beams. For this method, in both the first and second embodiments, the amplitude of the wavenumber-filtered spatially filtered scattered probe beam imaged to the selected detector pinhole and its selected detector pin The ratio of the amplitude of the wave number filtered spatially filtered reflected reference beam focusing on the hole can be adjusted.

Next, a third embodiment will be described. This third embodiment is a method and apparatus for identifying the complex amplitude of the in-focus image and the complex amplitude of the out-of-focus image. In this embodiment, the method of adjusting or improving or optimizing the S / N ratio is used. use. The apparatus is the same as the first embodiment, but using optical techniques, the amplitude of the wavenumber-filtered spatially filtered scattered probe beam imaged to the selected detector pinhole and its selected detection The amplitude ratio of the wave number filtered spatially filtered reflected reference beam focused on the detector pinhole is adjusted. In this case, light from a broadband, spatially incoherent point light source is focused on the light source pinhole. After that, the rays diverging from the light source pinhole are collimated and
Pointed to one phase shifter. The phase of the first part of the collimated light beam is shifted, which is the first quantity of the light beam after the phase shift. Also, the phase of the second part of the collimated light beam is shifted, and becomes the second amount of the light beam after the phase shift.

After the phase shift, the first and second quantities of the light beam reach the first beam splitter. After this, the first part of the first quantity of the light after the phase shift passes through the first beam splitter,
This is the first amount of the probe beam. The second portion of the first quantity of the phase shifted light ray is reflected by the first beam splitter to form a reference beam first quantity. Similarly,
The first part of the second quantity of the light beam after the phase shift passes through the first beam splitter to become the second quantity of the probe beam. The second part of the second quantity of the phase shifted light ray is reflected by the first beam splitter to form a reference beam second quantity. The first and second quantities of the probe beam focus on the first probe beam spot. The reference beam first quantity and the second quantity focus on the first reference beam spot.

A first amount of the probe beam diverging from the first probe beam spot is collimated and directed to a second beam splitter. Some of the collimated light beams pass through the second beam splitter, which becomes the third amount of the probe beam. A second amount of light from the probe beam diverging from the first probe beam spot is also collimated and directed to the second beam splitter. Some of the collimated light beams pass through the second beam splitter and become the fourth amount of the probe beam. The third and fourth rays of the probe beam are directed to a second phase shifter. After passing through the second phase shifter, the third beam of the probe beam is phase-shifted to a fifth beam of the probe beam. After passing through the second phase shifter, the fourth beam of the probe beam is phase-shifted to a sixth beam of the probe beam. Probe beam 5th and 4th
When 6 quantities are formed, the degree of phase shift performed by the second phase shifter is
This is the same as the case of the first phase shifter.

The first amount of reference beam rays diverging from the first reference beam spot are collimated and directed to a third phase shifter, which becomes the third amount of reference beam. The second beam of reference beam diverging from the first reference beam spot is also collimated and directed to the third phase shifter, which becomes the fourth beam of reference beam. Reference beam 3rd and 4th
When the quantity is formed, the degree of phase shift performed by the third phase shifter is
This is the same as the case of the first phase shifter. A part of the third reference beam quantity is reflected by the third beam splitter to become the fifth reference beam quantity. Similarly, a portion of the reference beam fourth quantity is reflected by the third beam splitter and the reference beam
It becomes 6 quantities. The fifth and sixth quantities of the collimated reference beam are focused by the reference lens to a second reference beam spot on the reference mirror.

The fifth and sixth quantities of the collimated probe beam are focused by the probe lens and form a line image on the target material, ie illuminate the target material. The line image is formed substantially along the optical axis of the probe lens, and the length of the line image on the optical axis is determined by a combination of various factors such as the depth of focus of the probe lens, chromatic aberration, and the optical band of the light source.

[0086] Of the probe beams diverged from the irradiation target toward the probe lens,
The reflected or scattered light corresponding to the fifth and sixth quantities forms a scattered probe beam. This scattered probe beam is collimated by the probe lens and
Pointed to the phase shifter. A phase shift is performed on the first portion of the collimated light beam, and the light beam formed by this shift becomes the first amount of the scattering probe beam after the phase shift. Further, a phase shift is performed on a second portion of the collimated light beam, and this is the second amount of the scattering probe beam after the phase shift. The first and second quantities of the scattered probe beam are directed to a second beam splitter. Here, a part of each of the first amount and the second amount of the scattering probe beam is
A third quantity and a fourth quantity of the scattered probe beam are formed through reflection by the second beam splitter. Thereafter, the third and fourth amounts of the parallel rays of the scattered probe beam are focused by the spatial filter lens at the spatial filter pinhole.

The reflected rays diverging from the second reference beam spot on the reference mirror towards the reference lens form a reflected reference beam. This reflected reference beam is collimated by the reference lens and directed to the third beam splitter. Part of the reflected reference beam is propagated by the third beam splitter and reaches the fourth phase shifter. Where the
The four phase shifter shifts the phase of the first portion of the propagated reflected reference beam, which becomes the phase-shifted first amount of the reflected reference beam. In addition, the phase of the second portion of the propagated reflected reference beam is shifted, and this is the phase-shifted second amount of the reflected reference beam. Both the first and second rays of the phase-shifted reflected reference beam are
Pointed to the beam splitter. Here, the second beam splitter propagates a part of the first reference amount and the second amount of the reflected reference beam, and becomes the third and fourth amounts of the reflected reference beam, respectively. After this, the third and fourth rays of the collimated reflected reference beam are focused on the spatial filter pinhole by the spatial filter lens.

A part of the third quantity of the scattered probe beam and a part of the fourth quantity are respectively passed through the spatial filter pinhole and then subjected to the spatially filtered third quantity of the scattered probe beam and spatially filtered. A fourth quantity of the scattered probe beam is formed.
Both the third and fourth quantities of the spatially filtered scattered probe beam are collimated by the dispersive element lens and directed to the dispersive element.
In this case, it is desirable to use a reflection type diffraction grating as the dispersion element.

A part of the third quantity of the reflected reference beam and a part of the fourth quantity respectively pass through the spatial filter pinhole and then are respectively subjected to the spatially filtered reflected reference beam third quantity.
The quantity forms a fourth quantity of the spatially filtered reflected reference beam. Both the third and fourth quantities of the spatially filtered reflected reference beam are collimated by a dispersive element lens and directed to the dispersive element.

The third spatially filtered scattered probe beam quantity emanating from the dispersive element and the fourth spatially filtered scattered probe beam quantity both pass through the detector lens and have respective wavenumbers A filtered spatially filtered scattered probe beam third quantity, and a wavenumber filtered spatially filtered scattered probe beam fourth quantity. The third and fourth quantities of this wavenumber filtered spatially filtered scattered probe beam are focused by a detector lens and a line image on a plane where a plurality of detector pinholes are linearly arranged. To form In addition, both the third spatially filtered reflected reference beam and the fourth spatially filtered reflected reference beam emanating from the dispersive element partially pass through the detector lens and are each subjected to wavenumber filtering. The third amount of the spatially filtered reflected reference beam and the fourth amount of the wave number filtered spatially filtered reflected reference beam are obtained. This wavenumber filtered spatially filtered reflected reference beam third quantity and fourth
The quantities are focused by a detector lens to form a line image on a plane where a plurality of detector pinholes are linearly arranged.

Wave Number Filtered Spatial Filtered Scattering Probe Beam Third
The third and fourth quantities, the quantity and fourth quantity, and the wavenumber-filtered spatially filtered reflected reference beam, are transmitted by the detector pinhole in partially overlapping form, but the intensity of this part Is measured by a multi-pixel detector. A plurality of pixels are linearly arranged in the multi-pixel detector, and a value measured by the detector becomes a first array of measured intensity values. In addition, the phase of the third and fourth quantities of the spatially filtered reflected reference beam, which has been subjected to wave number filtering, are shifted using radians by a fifth phase shifter, and the first and second phase shifted spatially filtered wave filters, respectively. The third and fourth quantities of the processed reflected reference beam are formed. This is followed by a wavenumber-filtered spatially filtered scattered probe beam third and fourth quantities, and a wavenumber-filtered spatially filtered reflected reference beam third and fourth quantities after the first phase shift. Are transferred by the detector pinholes in a partially overlapping manner, and the intensity of the overlapped portion is measured by a multi-pixel detector. The value measured here is the second array of measured intensity values.

Further, the wave number filtered spatially filtered reflected reference beam
The phases of the third and fourth quantities are again shifted using radians by the fifth phase shifter, and the third and fourth quantities of the spatially filtered reflected reference beam after the second phase shift are filtered, respectively. It is formed. Thereafter, a wavenumber-filtered spatially filtered scattered probe beam third and fourth quantities,
After the second phase shift, the wavenumber-filtered spatially filtered reflected reference beam is transmitted by the detector pinhole in a partially overlapping manner with the third and fourth quantities, and the intensity of the overlapping section is high. Measured by a pixel detector,
The value measured here becomes the third array of measured intensity values.

Similarly, the phase of the spatially filtered reflected reference beam third and fourth quantities, further wavenumber filtered, are again shifted using radians by a fifth phase shifter, and the wavenumber after the third phase shift A filtered spatially filtered reflected reference beam third quantity and fourth quantity are respectively formed. This is followed by the third and fourth quantities of wavenumber filtered spatially filtered scattered probe beams and the third and fourth quantities of wavenumber filtered spatially filtered reflected reference beams after the third phase shift. Are transferred by the detector pinholes in a partially overlapping manner, and the intensity of the overlapped portion is measured by a multi-pixel detector. The value measured here becomes the fourth array of measured intensity values.

In the next step, the first, second, third and fourth arrays of measured intensity values are sent to a computer for processing. The computer subtracts the corresponding elements of the second array of measured intensity values from the elements of the first array of measured intensity values to calculate a first array of component values that are the measured values. This first array of component values represents the complex amplitude of the scattered probe beam focused on the plane of the detector pinhole, and the effects of light rays due to out-of-focus images are largely eliminated. Similarly, the computer subtracts the corresponding element of the fourth array of measured intensity values from the element of the third array of measured intensity values, and this measurement is referred to as the second component value.
It becomes an array. The second array of component values represents the complex amplitude of the scattered probe beam focused on the plane of the detector pinhole and the effects of light rays due to out-of-focus images are largely eliminated.

The first array of component values and the second array of component values, which indicate the complex amplitude of the wavenumber filtered spatially filtered scattered probe beam, are the values of the quadrature components, and are therefore on the plane of the detector pinhole. It provides an accurate measurement of the complex amplitude of the scattered probe beam, which is focused and largely free of the effects of light rays due to out-of-focus images, within complex constants. Using a computer or computer algorithms now known in the art,
An accurate one-dimensional representation can be obtained without scanning the target material. This is because the direction of the linear portion matches the direction of the optical axis of the probe lens. By using a computer or a computer algorithm known in the art,
The dimensional representation and the three-dimensional representation are also accurately obtained based on the two-dimensional array and the three-dimensional array, respectively. In this case, the two-dimensional array is a computer controlled translator that scans the target material in one dimension to obtain the first, second, third, and third measured intensity values.
In the fourth array, the three-dimensional array includes first, second, third, and fourth arrays of measured intensity values obtained by scanning the target material in two dimensions. In this case, as a computer algorithm, a deconvolution or an integer equality inversion method which is currently known in the art may be used. The out-of-focus image has already been corrected in the first and second arrays of the component values of the amplitude of the scattered probe beam according to the present invention, but can be further corrected by using a deconvolution technique or the like.

In the third embodiment, it is possible to adjust, improve, and optimize the measurement S / N ratio of the complex amplitude, and the target complex amplitude can be measured by such processing. Optimization of S / N ratio
Wavenumber-filtered spatially filtered scattered probe beam to be focused on the selected detector pinhole Ratio of the third and fourth amplitudes and wavenumber filtered to focus on the selected detector pinhole This is performed by adjusting the ratio of the amplitudes of the third and fourth amounts of the reflected reference beam subjected to the spatial filtering. This ratio can be adjusted by changing the reflection and propagation properties of the first, second, and third beam splitters.

Next, a fourth embodiment will be described. This third embodiment is a method and apparatus for distinguishing between the complex amplitude of an in-focus image and the complex amplitude of an out-of-focus image, using a technique of adjusting or improving or optimizing the S / N ratio. In this embodiment, optical radiation from a broadband, spatially incoherent line source is imaged onto a linear array of source pinholes. The apparatus and electronic processing method used in this embodiment are slightly different from those in the third embodiment. That is, a linear array of light source pinholes is used instead of the light source pinholes of the third embodiment. Also, a linear array of spatial filter pinholes is used instead of the spatial filter pinholes of the third embodiment. Also,
Instead of the linear array of detector pinholes and multi-pixel detectors of the third embodiment, a multi-pixel detector having a two-dimensional linear array of detector pin holes and two-dimensional array pixels is used. Both the direction of the light source pinholes in the linear array and the direction of the spatial filter pinholes in the linear array are perpendicular to the plane defined by the dispersive element. The two-dimensional linear array of detector pinholes and the pixels of the multi-pixel detector are directed against an image of the linear array of light source pinholes imaged in the focal plane of the multi-pixel detector.

The first and second component values of the amplitude of the wavenumber-filtered and spatially-filtered scattered probe beam are based on the fact that the elements of the measurement array are quadrature component values and therefore the detection of a two-dimensional linear array. It provides an accurate measurement of the complex amplitude of the scattered probe beam within the complex constant, focused on the plane of the detector pinhole and greatly eliminating the effects of light rays due to out-of-focus images. Using computer algorithms now known in the art, an accurate two-dimensional representation of the two-dimensional portion of the target material can often be obtained without scanning the target material. This is because the two-dimensional portion is selected based on the direction of the linear array of light source pinholes and the direction of the optical axis of the probe lens. In addition, by using computer algorithms currently known in the art, the three-dimensional representation of the target material
It is scanned in two dimensions and is obtained exactly using a three-dimensional array of the first, second, third and fourth intensity values obtained therefrom. In this case, as a computer algorithm, a deconvolution or an integer equality inversion method which is currently known in the art may be used. The out-of-focus image has already been corrected in the first and second arrays of the component values of the amplitude of the scattered probe beam according to the present invention, but can be further corrected by using a deconvolution technique or the like.

In the fourth embodiment, it is possible to adjust, improve, and optimize the measurement S / N ratio of the complex amplitude, and the target complex amplitude can be measured by such processing. Optimization of S / N ratio
Wavenumber-filtered spatially filtered scattered probe beam to be focused on the selected detector pinhole Ratio of the third and fourth amplitudes and wavenumber filtered to focus on the selected detector pinhole This is performed by adjusting the ratio of the amplitudes of the third and fourth amounts of the reflected reference beam subjected to the spatial filtering. This ratio can be adjusted by changing the reflection and propagation properties of the first, second, and third beam splitters.

Next, a modification of the fourth embodiment will be described. This variation is a method and apparatus for distinguishing in-focus and out-of-focus images, the method comprising a broadband, spatially extended and spatially incoherent line source. This is to image the light source slit based on the optical radiation.
In this modification, an apparatus and an electronic processing method which are slightly different from those of the fourth embodiment are used. That is, a light source slit is used instead of the light source pinhole of the linear array of the fourth embodiment. Also, a spatial filter slit is used in place of the linear array spatial filter pinhole of the fourth embodiment. The directions of the light source slit and the spatial filter slit are both perpendicular to the plane defined by the dispersive element.

The first and second component values of the amplitude of the spatially filtered scattered probe beam subjected to wavenumber filtering, the elements of the measurement array are orthogonal component values. By its nature, the complex amplitude of a wavenumber-filtered spatially filtered scattered probe beam that is focused on the plane of the detector pinhole in a two-dimensional array, while greatly eliminating the effects of light rays due to out-of-focus images Shows an accurate measurement value within the range of the complex constant. Using computer algorithms known in the art, an accurate two-dimensional representation of the two-dimensional portion of the target material can be obtained without having to scan the target material. This is because the two-dimensional part is selected based on the direction of the light source slit and the direction of the optical axis of the probe lens. In addition, by using computer algorithms that are currently known in the art, the three-dimensional representation of the target material is
The object is scanned in one dimension and is accurately acquired using the resulting three-dimensional array of first, second, third and fourth intensity values. Scanning of the target material is accomplished by systematically moving the target material in one dimension using a translator controlled by a computer. In this case, as a computer algorithm, a deconvolution or an integer equality inversion method which is currently known in the art may be used. Although the out-of-focus image is also corrected by the apparatus of the present invention, the correction can be further performed by using a deconvolution method or the like.

In the apparatus of the present invention, a probe lens is used in any of the first, second, third, and fourth embodiments and the modifications. The probe lens can extend the focal range based on the wavelength. Even when the focus range is extended, the horizontal spatial resolution of each frequency component is kept high. With a probe lens, assuming a single wavelength,
The focus range is limited to an area defined by its numerical aperture,
Expansion is possible by using a lens whose focal length is designed in consideration of the wavelength. Lenses based on this type of wavelength can be designed using currently known techniques. As a design method, for example, there is a lens multiplet incorporating a plurality of refractive materials having different wavelength dispersions. There is also a lens design using a zone plate. When a zone plate is used, it is desirable to design the probe lens unit such that most of the optical beam components at any wavelength are focused in the order of the zone plate. Zone plates can be created using holographic techniques. When extending the focal range by the above method, the properties of the beam from the light source must be matched with the properties of the probe lens, that is, the wavelength band must be the same as the wavelength range of the probe lens.

The above-described first, second, third, and fourth embodiments and their modifications are the same as those of the first embodiment.
One group. In addition, the fifth, sixth, seventh, and eighth embodiments and their modifications are referred to as a second group of the embodiments. The fifth, sixth, seventh, and eighth embodiments and their modifications correspond to the first, second, third, and fourth embodiments and their modifications, respectively, except for the probe lens. In other words, in the first group of the embodiments, as the probe lens, a lens whose chromatic aberration is in the axial direction, that is, the vertical direction is used,
In the case of the second group, a probe lens having chromatic aberration in the horizontal direction is used. By using a probe lens having a lateral chromatic aberration, in each embodiment of the second group, a line image is formed on the target material substantially perpendicular to the optical axis of the probe lens. Also, the image points of the line image are obtained almost simultaneously.

The length of the line image formed perpendicular to the optical axis of the probe lens is determined by the focal length of the probe lens, the magnitude of lateral chromatic aberration (both can be adjusted), the optical band of the light source, and the like. It depends on the combination of various factors.

The ninth, tenth, eleventh, and twelfth embodiments and their modifications are referred to as a third group of the embodiments. The ninth, tenth, eleventh, and twelfth embodiments and their modifications are partially modified from the first, second, third, and fourth embodiments and their modifications. That is, the third group does not use a multi-element phase shifter. Therefore, in the third group of embodiments and modifications, the degree of background limitation and correction due to an out-of-focus image is reduced. In the third group, as in the first group, a probe lens having chromatic aberration in the optical axis direction is used. By using the probe lens having the chromatic aberration in the optical axis direction, in each embodiment of the third group, a line image is formed on the target material substantially along the optical axis of the probe lens. Also, the image points of the line image are obtained almost simultaneously.

Further, the thirteenth, fourteenth, fifteenth, and sixteenth embodiments and their modifications are referred to as a fourth group of the embodiments. The thirteenth, fourteenth, fifteenth, and sixteenth embodiments and their modifications are obtained by partially modifying the fifth, sixth, seventh, and eighth embodiments and their modifications. For this fourth group, no multi-element phase shifters are used.
Therefore, in the fourth group of embodiments and modifications, the degree of background limitation and correction due to an out-of-focus image is reduced. In the fourth group, as in the second group, a line image is formed on the target material using a probe lens having chromatic aberration in the horizontal direction. When a probe lens having a lateral chromatic aberration is used, a line image is formed on a target material in a form substantially perpendicular to (vertically) the optical axis of the probe lens. Also,
The image points of the line image are acquired almost simultaneously.

Further, the seventeenth, eighteenth, nineteenth, and twentieth embodiments and their modified examples constitute a fifth group of the embodiments. The seventeenth, eighteenth, nineteenth, and twentieth embodiments and their modifications are another modified version of the first, second, third, and fourth embodiments and their modifications. In other words, in the fifth group, the type of the probe lens is the first
Similar to the group, a probe lens having chromatic aberration in the axial direction is used, but a lens having almost no chromatic aberration in the axial direction is used. Therefore, in the case of the fifth group, the image generated on the target material is nominally a point image. Further, since the multi-element phase shifter is used similarly to the first group, in the fifth group, the degree of restriction and correction of the background by the out-of-focus image is equal to the degree of restriction and correction of the background by the out-of-focus image of the first group. Is the same. In the case of the fifth group, the image points are sequentially acquired as time elapses.

According to the embodiments of the first four groups of embodiments and variants thereof, the S / N ratio can also be adjusted and / or optimized for a plurality of optical frequency components of the light source. This involves placing a wavelength filter in the path of the reference and / or reflected reference beam, preferably and / or in the path of the probe and / or scattered probe beam, and configured to transmit through the wavelength filter to have a predetermined wavelength dependence. Then, pass through the individual detector pinholes for different wavelengths and generate a wave number filtered and spatially filtered reflected reference beam and a wave number filtered and spatially filtered scattering probe beam. This is achieved by adjusting and / or optimizing the ratio.
This feature is particularly useful where the probe and scattered probe beams are greatly attenuated as they pass through the material of interest.

For each of the five groups of embodiments of the embodiments and variations thereof, there is a corresponding embodiment or variation of writing information to a target material having a recording medium. Each of the embodiments for writing information and its variants have the corresponding method or apparatus of the embodiment or variant, except for the following changes in the configuration. The light source and reference mirror subsystem are replaced, and the detector and detector pinhole are replaced with a mirror, where the mirror is
Directing light from the light source impinging on the mirror substantially behind itself, the degree of temporally and spatially dependent reflection and the temporally and spatially dependent phase shift together with the phase shifting means Produced by the placed mirror, it produces the desired image in the target material. The phase shifting means performs the same function as the means for providing a series of phase shifts in the wave number filtered and spatially filtered reflected reference beam, and is an embodiment of the five groups of embodiments and variants thereof. For the embodiment, the first, second,
Obtain third and fourth measured intensity values.

For certain of the embodiments and variations thereof described herein, information is stored at predetermined locations within the target material using a single bit binary format. In certain of the embodiments and variations thereof described herein, higher density information storage than is achievable with certain embodiments and variations thereof may be achieved with an amplitude recording medium or amplitude and phase recording. At each data storage location on the medium, a base N format for amplitude,
Alternatively, it is obtained by recording in (base N) × (base M) format for amplitude and phase information.

As will be apparent to those skilled in the art, in the wave number filtered and spatially filtered reflected reference beam, a series of phase shifts is provided, and the first, second, and third embodiments are modified with respect to the foregoing embodiments and variations. Means for obtaining the second, third, and fourth measured intensity values are also implemented by phase discrimination detection and heterodyne detection techniques without departing from the scope and spirit of the invention. For example, a phase shifting means consisting of four discrete phase shift values of 0,,, and radians is replaced by a sinusoidal phase change of amplitude at frequency. The first and second components of the complex amplitude of the wavenumber filtered and spatially filtered scattered probe beam are detected as first and second harmonics, respectively, by phase discrimination detection. The amplitude is chosen to be sensitive to detection of both the first and second harmonics. In a second example, the frequency of the reference beam is shifted with respect to the frequency of the probe beam, and the complex amplitudes of the scattered probe beam are filtered, e.g., by an acousto-optic modulator. The second component value is obtained by heterodyne detection.

As will be apparent to those skilled in the art, embodiments and variations thereof for writing information to an optical disc may write information to storage locations in a single bit binary format. Further, as will be apparent to those skilled in the art, embodiments and variations thereof for writing information to an optical disc may be based on a base N format for amplitude or a (base N) × (base M) format for amplitude and phase at certain storage locations. When the stored information is converted into the (base N) × (base M) format, the information is converted by Fourier transform, Hilbert transform, or the like.

As will be apparent to those skilled in the art, information is stored on the medium by magneto-optical effects and the stored information is read out by measuring changes in the state of polarization of the probe beam scattered or transmitted through the material of interest. It is.

As will be apparent to those skilled in the art, in the five groups of embodiments and associated writing embodiments and variations thereof, and variations thereof, the desired scan of the target material is such that the target material is stationary. It is also realized by scanning the image of each light source pinhole, a linear array of light source pinholes, or a light source slit in the target material while keeping it as it is.

It will be appreciated that the "licensing technique" of the present invention applies to any electromagnetic wave, for example an electron beam or sound wave used in an electron microscope, and therefore has the appropriate collimator lens, imaging A lens, a phase shifter, and a recording medium are provided. For applications where the amplitude of the beam is detected instead of intensity, the function of generating the square of the amplitude must be performed in the next electronic processing of the detector.

[0116] It will also be appreciated that the length of the linear image in the material of interest can be varied, for example, by changing the optical bandwidth of the light source as needed, for example, the depth of focus and / or axial chromatic aberration of the probe lens, or It is changed by changing the lateral chromatic aberration of the probe lens.

The use of a spatially incoherent linear source generally results in lower systematic errors, but the linear source is, in the case of the second or fourth preferred embodiment, or a variant thereof, a systematic error. It is not necessary to be spatially incoherent in the direction of the linear source to reduce the target error.

The advantages of certain of the first and third groups of embodiments for reading multi-layer multi-track optical discs are that the linear sections in the depth direction of the optical disc can be imaged substantially simultaneously and the conventional single pinhole It means that statistical errors are significantly reduced and background from out-of-focus images is significantly reduced compared to that obtained by a series of measurements using a confocal interference microscope or holography, or the like. Simultaneously imaging the linear sections in the depth direction of the optical disk can greatly reduce the sensitivity to optical disk movement in the depth direction caused by rotation of the optical disk, unevenness of the optical disk, and / or vibration of the optical disk. Simultaneously imaging the linear sections in the depth direction of the optical disc also allows the reference surface of the optical disc to be identified, together with the information simultaneously obtained from the multilayer film, this reference layer serving for alignment.

An advantage of certain of the first and third groups of embodiments in providing amplitude images of complex slices of a wafer used in the manufacture of integrated circuits is that a linear section in the depth direction of the wafer is substantially reduced. And significantly reduce statistical errors compared to those obtained by a series of measurements using a conventional single pinhole confocal interference microscope or holography, or the like, and reduce the out-of-focus image from the out-of-focus image. Is significantly reduced. Simultaneously imaging linear sections in the depth direction of the wafer,
The sensitivity to wafer movement in the depth direction, for example, caused by translation, scanning, or vibration of the wafer, can be greatly reduced. Simultaneous imaging of linear sections in the depth direction of the wafer further allows identification of the wafer surface and / or internal surfaces, with information obtained simultaneously from multiple depths.

[0120] Certain of the first and third groups of embodiments of the present invention relate to providing amplitude images of complex slices of a biological sample in vivo, such as images used in non-invasive biopsy of a biological sample. The advantage is that a linear section in the depth direction of the biological sample is imaged substantially simultaneously and is obtained in a series of measurements using a conventional single pinhole confocal interference microscope or holography, or similar. Significantly reduce the statistical error compared to
This means that background from out-of-focus images is significantly reduced. Simultaneous imaging of a linear section in the depth direction of a biological sample greatly reduces sensitivity to movement of the biological sample in the depth direction, for example, caused by translation, scanning, or vibration of the biological sample. it can. Simultaneously imaging the linear sections in the depth direction of the biological sample also allows the identification of the biological sample surface and / or the interior surface, with information obtained simultaneously from multiple depths.

Another advantage of certain other advantages of the first and third groups of embodiments for reading a multi-layer multi-track optical disc is that two-dimensional sections in the depth direction of the optical disc can be imaged substantially simultaneously. Significantly reduce statistical errors and significantly reduce background from out-of-focus images compared to those obtained with a series of measurements using a single pinhole and slit confocal interference microscope or holography, or the like. That is to decrease. One of the axes of the two-dimensional section of the optical disk is parallel to the depth direction of the optical disk, and the axis of the two-dimensional section of the optical disk in the orthogonal direction is parallel to the radial direction of the optical disk. It may be parallel to the tangential direction of the track. Simultaneously imaging two-dimensional sections of the optical disk can greatly reduce sensitivity to optical disk movement in the depth and radial directions caused by optical disk rotation, optical disk non-planarity, and / or optical disk vibration. Simultaneous imaging of the two-dimensional sections of the optical disc further allows identification of the reference surface, or reference layer, and reference tracks on or within the optical disc, along with information obtained simultaneously on the multilayer and multiple tracks, for track identification. Used, this reference layer and reference track function for alignment.

The advantages of certain of the second and fourth groups of embodiments for reading a multi-layer multi-track optical disc are that the linear sections in the optical disc or adjacent to the layers on the optical disc are imaged substantially simultaneously, and the conventional single Significantly reduce statistical errors and significantly reduce background from out-of-focus images compared to a series of measurements using a single pinhole confocal interference microscope or holography, or the like. It is. Simultaneous imaging of linear sections within or on a layer on an optical disk can greatly reduce sensitivity to optical disk movement caused by optical disk rotation and / or optical disk vibration. Simultaneous imaging of the two-dimensional sections in or on the layer on the optical disc also allows identification of a reference track on the optical disc, together with information obtained from a number of tracks, which serves as an alignment.

The advantages of certain of the second and fourth groups of embodiments in providing amplitude images of complex slices of a wafer used in the manufacture of integrated circuits are that the straight lines tangent to the wafer surface or to a surface within the wafer. Imaging the sections substantially simultaneously, significantly reducing statistical errors compared to those obtained with a series of measurements using a conventional single pinhole confocal interference microscope or holography, or the like, This means that background from out-of-focus images is significantly reduced. Simultaneous imaging of linear sections tangent to the wafer surface or surfaces within the wafer can greatly reduce the sensitivity to wafer movement caused by translation, scanning, and / or vibration of the wafer. Simultaneous imaging of two-dimensional sections in contact with a surface in or on the wafer can further identify the reference position in the wafer or on the wafer, along with information obtained simultaneously from multiple locations, and this reference position is used for alignment. Function.

Another advantage of certain of the first and third groups of embodiments for providing an amplitude image of a complex slice of a wafer used in the manufacture of integrated circuits is that the two-dimensional sectioning of the wafer is substantially reduced. Simultaneously imaged, significantly reduced statistical errors compared to those obtained with a series of measurements using conventional single pinhole and slit confocal interference microscopy or holography, or the like, out-of-focus images Is significantly reduced. One of the axes of the two-dimensional section of the wafer is parallel to the depth direction of the wafer. Simultaneous imaging of two-dimensional sections of the wafer can greatly reduce sensitivity to depth and lateral movement of the wafer caused by translation, scanning, and / or vibration of the wafer. Simultaneous imaging of a two-dimensional section of the wafer can further identify the wafer or internal surface, along with information obtained simultaneously from multiple other locations, which surface and / or internal surface can serve as an alignment. Can be.

[0125] Certain other of the first and third groups of embodiments relating to providing amplitude images of complex slices of a biological sample in vivo, such as those used in non-invasive biopsy of biological samples. Another advantage of the one is that it images substantially two-dimensional sections of a biological sample substantially simultaneously,
Significantly reduce statistical errors and significantly reduce background from out-of-focus images compared to those obtained with a series of measurements using conventional single pinhole and slit confocal interference microscopy or holography, or the like. That is to reduce it. One of the axes of the two-dimensional section of the biological sample is parallel to the depth direction of the wafer. Simultaneous imaging of the two-dimensional section of the wafer can greatly reduce the sensitivity to biological sample movement caused by translation, scanning, and / or vibration of the biological sample.
Simultaneous imaging of a two-dimensional section of a biological sample can further identify the surface or interior surface of the biological sample, along with information obtained simultaneously from multiple other locations, where the surface and / or interior surface is located. It can function as a match.

[0126] Certain of the examples of the second and fourth groups of embodiments relating to providing amplitude images of complex tomography of a biological sample in vivo, such as those used in non-invasive biopsy of a biological sample. The advantage is that it images substantially simultaneously a linear section that touches a surface within or on the sample, and that can be obtained with a series of measurements using a conventional single pinhole confocal interference microscope or holography, Or significantly reduce statistical errors and significantly reduce background from out-of-focus images as compared to the like. Simultaneous imaging of a linear section that touches a surface within the sample or a surface on the sample can greatly reduce the sensitivity to movement of the sample caused by translation, scanning, and / or vibration of the sample. Simultaneously imaging a two-dimensional section in contact with a surface in the sample or a surface on the sample further enables identification of a reference position in the sample along with information obtained simultaneously from a plurality of positions, and the reference position is used for positioning. Function as

Another advantage of certain other aspects of the second and fourth groups of embodiments for reading multi-layer multi-track optical discs is that the two-dimensional sections of the optical disc can be imaged substantially simultaneously and a conventional single pin Significantly reduce statistical errors and significantly reduce background from out-of-focus images compared to those obtained by a series of measurements using a hole and slit confocal interference microscope or holography, or the like. It is.
One of the axes of the two-dimensional section of the optical disc may be parallel to the radial direction of the optical disc, and the orthogonal axis of the two-dimensional section of the optical disc may be the tangential direction of the tracks in or on the optical disc. And can be parallel. Simultaneously imaging two-dimensional sections of the optical disk can greatly reduce the sensitivity to optical disk movement in the radial direction caused by optical disk rotation and / or optical disk vibration. Simultaneous imaging of a two-dimensional section within or on an optical disc further provides information simultaneously obtained from multiple tracks and multiple locations on the multiple tracks, as well as for track identification and read error of a given track. A reference track can be identified and this reference track serves for alignment.

An advantage of the fifth group of embodiments for reading multi-layer multi-track optical discs is that they produce one-, two-, or three-dimensional images of multi-layer multi-track optical discs and use a conventional single pinhole confocal interference microscope or This means that background from out-of-focus images is significantly reduced as compared to that obtained with a series of measurements using holography.

The advantages of the fifth group of embodiments for providing amplitude images of complex slices of a wafer used in the manufacture of integrated circuits are that one-, two-, or three-dimensional images of the wafer can be generated This means that background from out-of-focus images is significantly reduced compared to that obtained with a series of measurements using a single pinhole confocal interference microscope or holography.

An advantage of the fifth group of embodiments for providing amplitude images of complex tomography of a biological sample in vivo, such as those used in non-invasive biopsy of a biological sample, is that Generates one-, two-, or three-dimensional images and significantly reduces background from out-of-focus images compared to those obtained with a series of measurements using conventional single pinhole confocal interference microscopy or holography That is.

The advantages of the first four groups of embodiments of the present invention are that the linear sections are imaged substantially simultaneously and are obtained in a series of measurements using a conventional single pinhole confocal interference microscope. , Or the like, to significantly reduce the background from out-of-focus images. This substantially simultaneous imaging capability is made possible by the introduction of a technique called "optical wavenumber domain reflectometer" (OWDR). Background reduction is made possible by applying the basic principles of a pinhole confocal microscope to an interferometric measurement system. This substantially simultaneous imaging capability allows one-dimensional, two-dimensional, and three-dimensional
A two-dimensional image can be generated, greatly reducing the sensitivity to movement of the object during the measurement process. This problem of movement places great limitations on commonly used techniques for in vivo measurements of biological systems. PSI and SCLI, which do not incorporate the techniques disclosed herein, encounter significant limitations due to motion caused by vibration. Also, the problem of untracked motion places a great limitation on reading and / or writing of a multilayer multi-track optical disc.

Another advantage of the present invention is that the two-dimensional sections are imaged substantially simultaneously, and from the out-of-focus image compared to those obtained with a series of measurements using a conventional slit confocal interference microscope. That is to significantly reduce the background. This substantially simultaneous imaging capability is made possible by the introduction of OWDR technology. The background can be reduced by applying the basic principle of the slit confocal microscope to the interferometer system. This substantially simultaneous imaging capability can produce two-dimensional and three-dimensional images and greatly reduce the sensitivity to movement of the object during the measurement process. As already indicated, this motion problem is a problem commonly used in the in vivo measurement of biological systems, in PSI and SCLI due to the movement caused by vibration, the reading and / or reading of multi-layer multi-track optical discs. In writing, untracked movement places great restrictions.

The advantages of the embodiment for writing on the multi-layer multi-track optical disk and its modifications, that is, the embodiment corresponding to the predetermined one of the first and third groups of the embodiments and the predetermined one of the modifications, are as follows. Imaging substantially simultaneously a straight section in the depth direction of the image, compared to what is produced in a series of images using conventional single pinhole confocal interference microscopy or holographic imaging, or the like. Thus, statistical errors are significantly reduced and background from out-of-focus images is significantly reduced.
Simultaneously imaging the linear sections in the depth direction of the optical disk can greatly reduce the sensitivity to optical disk movement in the depth direction caused by rotation of the optical disk, unevenness of the optical disk, and / or vibration of the optical disk. Simultaneously imaging the linear sections in the depth direction of the optical disc also allows simultaneous writing of information to multiple layers and the creation of a reference plane within the optical disc, which serves as an alignment.

Further advantages of the embodiment for writing on a multilayer multi-track optical disc and its variants, ie an embodiment corresponding to certain of the first and third groups of embodiments and certain other of its variants. Image two-dimensional sections of an optical disk at substantially the same time, compared to those produced in a series of images using a conventional single pinhole and slit confocal interference microscope or holography, or the like. Thus, statistical errors are significantly reduced and background from out-of-focus images is significantly reduced.
One of the axes of the two-dimensional section of the optical disk is substantially parallel to the depth direction of the optical disk, and the orthogonal axis of the two-dimensional section of the optical disk is substantially parallel to the radial direction of the optical disk. Or substantially parallel to the tangents of the tracks on the optical disc, or in a direction therebetween. Simultaneously imaging two-dimensional sections of the optical disk can greatly reduce sensitivity to optical disk movement in the depth and orthogonal directions caused by optical disk rotation, optical disk non-planarity, and / or optical disk vibration. Simultaneously imaging a two-dimensional section of an optical disc further includes a reference surface, ie, a reference layer, within or on the optical disc, along with information that is simultaneously imaged on multiple layers and multiple tracks.
And a reference track can be generated, and the reference layer and the reference track function for alignment.

The advantages of the embodiment for writing on the multi-layer multi-track optical disk and its modifications, that is, the embodiment corresponding to the predetermined one of the embodiments of the second and fourth groups and the predetermined one of the modifications, are as follows. Or image a linear section tangent to a layer on an optical disc substantially simultaneously and produce a series of images using a conventional single pinhole confocal interference microscope or holography or similar. Thus, statistical errors are significantly reduced and background from out-of-focus images is significantly reduced. Imaging substantially simultaneously the linear sections within or on the layer on the optical disk can significantly reduce sensitivity to optical disk movement caused by optical disk rotation and / or optical disk vibration.

An embodiment for writing on a multi-layer multi-track optical disc and its modifications, ie, an embodiment corresponding to another predetermined embodiment of the second and fourth groups, and another predetermined embodiment of its modifications The advantage is that two-dimensional sections of an optical disc are imaged substantially simultaneously and are produced in a series of images using a conventional single pinhole and slit confocal interference microscope or holography, or the like. , The statistical error is significantly reduced, and the background from the out-of-focus image is significantly reduced. One of the axes of the two-dimensional section of the optical disc is substantially parallel to the radial direction on the optical disc, and the axis of the orthogonal direction of the two-dimensional section of the optical disc is tangent to a track in or on the optical disc. It can be substantially parallel to the direction. Simultaneously imaging two-dimensional sections of the optical disk can greatly reduce the sensitivity to optical disk movement in the radial direction caused by optical disk rotation and / or optical disk vibration. Simultaneously imaging the two-dimensional section of the optical disk further allows writing information to multiple tracks and multiple locations on multiple tracks simultaneously, as well as generating a reference track for track identification, wherein the reference layer and the reference track are Functions for alignment.

Embodiments for writing on a multi-layer multi-track optical disc and its modifications, that is, embodiments corresponding to the fifth group of embodiments and the advantages of the modifications thereof are described below. Alternatively, generating a three-dimensional image and significantly reducing the background from the out-of-focus image compared to that generated in a series of images using a conventional single pinhole confocal interference microscope or holography. is there.

An advantage of the present invention is that the complex scatter amplitude of the object is obtained instead of the magnitude of the scatter amplitude in the case of PCI and OCT. This is particularly important with respect to the amount of computer analysis required to obtain a one, two or three dimensional image of a given type of material of interest.

Another advantage is that the computer processing required to obtain complex scattering amplitudes in one-dimensional, two-dimensional, and three-dimensional imaging processing is less than the processing required in commonly used conventional confocal systems. It means that it is greatly reduced compared to.

Another advantage is that if a correction is needed for an out-of-focus image that has already been greatly reduced in the device of the present invention, it is necessary for the device of the present invention to achieve a given level of correction. That is, the computer processing required is significantly reduced as compared to the computer processing required with conventional scanning single pinhole and scanning slit confocal interference microscopes.

Another advantage is that for a single source pinhole, on a given lateral distance in the material of interest, background to statistical noise in the complex scattering amplitude measured at a given measurement time interval The independent measurement positions on the axial image distance are better than those obtained at similar time intervals with conventional scanning single pinhole confocal interference microscopy in each embodiment and variant of the invention, in each embodiment and variant of the invention. And the position is independent of the measured complex scattering amplitude. A similar advantage is provided for a slit confocal interference microscope in which the corresponding reduction factor is substantially proportional to the square root of the number of independent measurement positions of the imaged two-dimensional section of the target material.

Another advantage is that for a given measurement time interval, the contribution of background radiation to statistical noise at the complex scattering amplitude measured over a given imaged axial distance is The fact that the amplitude can be reduced to a radiation mainly derived from the size of the amplitude itself is particularly useful when the amplitude of the background radiation is relatively large compared to the size of the complex scattering amplitude. This cannot be achieved with conventional scanning single pinhole or slit confocal microscopes.

Another advantage is that, for certain embodiments of the first four groups of embodiments and variants thereof, substantially only a one-dimensional scan is required to generate a two-dimensional image,
That is, substantially only a two-dimensional scan is required to generate a three-dimensional image.

Another advantage is that, for certain other embodiments of the first four groups of embodiments and variants thereof, substantially only a one-dimensional scan is required to generate a three-dimensional image. That is.

The device of the present invention, in summary, (1) reduces systematic errors, (2) reduces statistical errors, and (3) reduces the dynamic range requirements for detectors, electronic processing, and recording media. (4) increasing the data density stored on the optical disc;
(6) reduce the computer processing required to generate either a two-dimensional, two-dimensional, or three-dimensional image; (7) It can operate even when an image is formed through a turbid medium. Generally, one or more of these features can be implemented for parallel operation.

In the drawings, similar reference features indicate similar components throughout the several views.

[0147]

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The present invention provides a method for reducing the complex amplitude of the light reflected and / or scattered by a volume element in a stereoscopic image space or area, by anterior, posterior and lateral structures of this element overlapping the volume element to be examined. Can be separated from the complex amplitude of the background light emitted by the out-of-focus image. The tomography technique described herein can separate the desired complex amplitude signal in the image plane from the "background" and "foreground" complex amplitude signals generated by various mechanisms. These background and foreground complex amplitude signals are: (1) an out-of-focus image of a section of the target material other than the imaged slice; (2) the desired amplitude signal scatter; and (3) the imaged slice. And / or (4) thermal radiation of signals emitted from other light sources. The scattering location and the thermal radiation source are located in a space in front of, behind, and / or inside the slice of the object to be examined.

The technique of the present invention is implemented at one or two different levels of discrimination for out-of-focus images. At the first level (Level 1), the impulse response function of the imaging subsystem operates in one plane by introducing a change in the primary phase pattern at the pupil of each subsystem of the device of the present invention. At the second level (Level 2), the impulse response function of the imaging subsection operates in two orthogonal planes by introducing changes in the secondary phase pattern at the pupil of each subsystem. Implementing level 2 provides more effective identification of out-of-focus images from in-focus images than implementing level 1. However, the second and fourth embodiments of the present invention,
In the case where the level 1 identification is used in any one of the sixth and sixth embodiments, the linear light source pinhole array is preferably formed as a slit.
When the level 2 identification is used in the embodiment and the sixth embodiment, the interval between the light source pinholes must be larger than the minimum value according to the following equation (38). Level 1
And Level 2 identification can be performed for any of the preferred embodiments described below.

The enabling techniques of the present invention, which are common to each of the preferred embodiments of the device of the present invention formed for either Level 1 or Level 2 identification, are described below for the preferred embodiments for Level 1 identification. I will explain only. Level 1 identification is based on a special direction in the orthogonal plane, in which the impulse response function of the imaging subsystem is manipulated. The choice of direction on the orthogonal plane where the impulse response function of the imaging subsystem is manipulated will affect the degree to which the effect of the background beam on the statistical error achieved with the device of the present invention is reduced.

Referring to the accompanying drawings in detail, FIGS. 1a to 1n schematically illustrate the presently preferred aspects of the first preferred embodiment of the present invention. As shown in FIGS. 1a through 1n, a preferred embodiment of the present invention comprises a beam splitter 100, a target material 112, an xyz translator 116, a reference mirror 120, and a dispersion detector element 130a.
, 130b and a detector 114. This configuration is known in the art as a Michelson interferometer and is shown as a simple example. Polarization Michelson interferometer, and C.I. Zanori's document entitled "Principles, Benefits, and Applications of Differential Interferometer Devices for Measuring Distances and Angles" (VDR Berich
te NR. 749, 93-106, 1989) and other forms of interferometers known in the art without significantly departing from the spirit and scope of the first preferred embodiment of the present invention. It can be incorporated into the device shown.

In the first embodiment, the orientation of the plane on which the impulse response function of the imaging subsystem is manipulated is perpendicular to the plane of FIG. 1a and parallel to the optical axis of the imaging subsystem. .

FIG. 1b shows, in schematic form, one embodiment of the subsystem 80 shown in FIG. 1a. For the first preferred embodiment, the light source 10 is preferably a point light source or a radiation source spatially incoherent over the surface of the light source, preferably a laser or similar coherent or partially coherent radiation. Source, preferably a polarized light source. The light source 10 emits an input beam 2 aligned with the optical axis 3 of the subsystem 80. As shown in FIG. 1b, the input beam 2 enters a focusing lens 6 and focuses on a pinhole 8 in an image plane 7. A plurality of light beams 12-1, 12
The light beam 12 including -2, 12-3, 12-4 diverges from the pinhole 8,
The optical axis enters the lens 16 which is aligned with the optical axis 3 of the subsystem 80. The light beam 12 exits the lens 16 as a collimated light beam 12A including the light beams 12A-1, 12A-2, 12A-3, 12A-4, and a phase shifter 14A.
To enter. The phase shifters 14 are rectangular phase shifters 14-1, 14-2, 14-3, arranged such that their respective optical axes are parallel to the optical axis 3 of the subsystem 80.
14-4. The number of phase shifters may be any suitable number, such as an integer 2m, m, etc. In the example shown in FIG. 1b, where m = 2, four phase shifters are sufficient to clearly show the relationship between the components of the device of the invention. The parallel light beams 12A-1, 12A-2, 12A-3, and 12A-4 pass through the phase shifters 14-1, 14-2, 14-3, and 14-4, respectively, and the light beams 12B-1 respectively. , 12B-2, 12B-3 and 12B-4 as phase shifters 14
Exit. These light beams constitute the light beam 12B. Phase shifter 1
Each of 4-2 and 14-4 introduces a phase shift π radians greater than the phase shift introduced by each of phase shifters 14-1 and 14-3. The phase shifts introduced by phase shifters 14-1 and 14-3 are the same.

In FIG. 1a, light beam 12B exits subsystem 80 and exits subsystem 81
To enter. In FIG. 1c, light beam 12B enters lens 26 and exits as light beam 12C, which includes light beams 12C-1, 12C-2, 12C-3, and 12C-4. The lens 26 focuses the light beam 12C on the point image 18 on the focused image plane 17. The light beam 12C includes the light beams 22-1, 22-2, 22-3, and 2
Exits point image 18 as light beam 22 containing 2-4. Light beam 22 enters lens 36 whose optical axis is aligned with optical axis 3 of subsystem 81. Light beam 2
2 exits lens 36 as a collimated light beam 22A including light beams 22A-1, 22A-2, 22A-3, 22A-4 and exits subsystem 81.

As shown in FIG. 1a, the light beam 22A is partially
0, and the light beams P22B-1, P22B-2, P22B-3, P22B
-4, and enters the subsystem 82 shown in FIG. 1d.

In FIG. 1d, the light beam P22B is divided into the phase shifters 24-1, 24-2,
4-3 and 24-4. The phase shifter 24 includes the same number of 2m elements as the phase shifter 14, and is indicated by m = 2 in FIG. 1d. The light beams P22B-1, P22B-2, P22B-3, and P22B-4 are phase shifters 24.
-1, 24-2, 24-3, and 24-4, respectively, and the light beam P22C-1,
It emerges as a light beam P22C that includes P22C-2, P22C-3, and P22C-4, respectively. The values of the phase shifts introduced by phase shifters 24-1 and 24-3 are the same and are π radians greater than the phase shifts introduced by either phase shifters 24-2 or 24-4. The values of the phase shifts introduced by the phase shifters 24-2 and 24-4 are the same.

The sum of the phase shifts introduced by each phase shifter pair 14-1 and 24-1, 14-2 and 24-2, 14-2 and 24-2, and 14-4 and 24-4 is
π radians. Thus, the light beams P22C-1, P22C-2, P22
There is no net relative phase shift between any two light beams of C-3 and P22C-4. The light beam P22C includes the light beams P22D-1 and P22D-2.
, P22D-3, P22D-4, pass through the lens 46 as light beams P22D, which are converted to point images 28 on a focused image plane 27 of the target material 112.
Is focused on. The optical axis of lens 46 is aligned with optical axis 3 of subsystem 82. The axis of the line image is substantially parallel to the optical axis 3 of the imaging subsystem 82. The length of the line image is determined by a combination of factors such as the depth of focus and chromatic aberration of the probe lens 46 and the optical bandwidth of the light source 10. The line section is
It may cut into one or more surfaces of the target material or may rest on the surface of the target material. The optical axis of lens 46 is aligned with optical axis 3 of subsystem 82.

In FIG. 1a, a part of the light beam 22A is reflected by the beam splitter 100 as a light beam R22B including the light beams R22B-1, R22B-2, R22B-3, R22B-4. Light beam R22B enters subsystem 83 shown in FIG. 1e. As shown in FIG. 1e, the light beam R22B is transmitted to the phase shifter 3 including the phase shifters 34-1, 34-2, 34-3, and 34-4.
Four hits. The phase shifter 34 includes the same number of 2m elements as the phase shifter 14, and is indicated by m = 2 in FIG. 1e. The light beam R22B passes through the phase shifter 44 after passing through the phase shifter 34, and the light beam R22C-1
, R22C-2, R22C-3, R22C-4. The phase shift introduced by the phase shifter 44
8 is controlled by the signal 132. The values of the phase shifts introduced by the phase shifters 34-1 and 34-3 are equal and the phase shifters 34-2 or 34-4
Π radians greater than the phase shift introduced by any of The value of the phase shift introduced by the phase shifter 34-2 or 34-4 is equal. Thus, there is no net relative phase shift between any two of the light beams R22C-1, R22C-2, R22C-3, R22C-4. Light beam R
22C is a light beam R22D-1, R22D-2, R22D-3, R22D-.
4 pass through the lens 56 as a light beam R22D. Light beam R22D
Is focused by the lens 56 on the point image 38 on the focused image plane 37 of the reflecting mirror 120. The optical axis of the lens 56 is aligned with the optical axis 3a of the subsystem 83.

In FIG. 1f, a part of the light beam P22D (see FIG. 1d) is reflected and / or scattered by the target material at the point image 28, and a plurality of light beams P32- constituting the light beam P32 are formed. 1, P32-2, P32-3, and P32-4. The light beam P32 diverges from the point image 28 on the focused image plane 27,
Enter 6. As can be seen in FIG. 1f, the light beam P32 is
Exits lens 46 as a collimated light beam P32A including 2A-1, P32A-2, P32A-3, and P32A-4. Light beam P32A-1, P3
2A-2, P32A-3, and P32A-4 are phase shifters 24-4, 24-3,
24-2 and 24-1, respectively, and the light beams P32B-1, P32B-2, P
32B-3 and P32B-4 respectively appear. Light beam P32B-1, P32B
-2, P32B-3, P32B-4 comprise a light beam P32B, which exits subsystem 82. The value of the phase shift introduced by the phase shifters 24-1 and 24-3 is equal and π radians greater than the phase shift introduced by the phase shifters 24-2 or 24-4. These phase shifters 24-
The value of the phase shift introduced by 2 or 24-4 is equal.

In FIG. 1g, the light beam R22D (see FIG. 1e) is reflected by the reflecting mirror 120 to become a light beam R32 including the light beams R32-1, R32-2, R32-3, and R32-4. . The light beam R32 is a point image 3 on the focused image plane 37.
8 diverges and enters the lens 56. As shown in FIG. 1g, the light beam R3
2 is a light beam R32A-1, R32A-2, R32A-3 from the lens 56.
, R32A-4, as a collimated light beam R32A. The light beams R32A-1, R32A-2, R32A-3, and R32A-4 first pass through the phase shifter 44, and then pass through the phase shifters 34-4, 34-3, and 34-2.
34-1 and the light beams R32B-1, R32B-2, R32B-3
, R32B-4. The phase shift introduced by phase shifter 44 is controlled by signal 132 from computer 118. The values of the phase shifts introduced by phase shifters 34-1 and 34-3 are equal and π radians greater than the phase shifts introduced by either phase shifters 34-2 or 34-4. The values of the phase shifts introduced by the phase shifters 34-2 and 34-4 are equal. Light beams R32B-1, R32B-2, R32B-3, R3
2B-4 comprises ray beam R32B exiting subsystem 83.

A part of the scattered probe beam P32B is reflected by the beam splitter 100 and is composed of the light beams P32C-1, -2, -3, and -4.
1C is shown in FIG. 1a. The scattering probe beam P32C is
The subsystem 81a shown in FIG. 1h is entered. The plane in FIG. 1h is orthogonal to the plane in FIG. 1a. In FIG. 1h, the scattered probe beam P32C enters the lens 26a having an optical axis aligned with the optical axis 3a of the subsystem 81a, and the scattered probe beam P32D is composed of the light beams P32D-1, -2, -3, and -4. Exit as P32D.
The lens 26a transmits the scattered probe beam P32D to the pinhole 18 in the image plane 17a.
Focus on a. A part of the scattered probe beam P32D is divided into light beams P42-1 and -2.
, -3, -4 exit the pinhole 18a as a spatially filtered scattered probe beam P42. The scattered probe beam P42 is transmitted to the subsystem 81a.
Enters the lens 36a having an optical axis aligned with the optical axis 3a. The spatially filtered scattered probe beam P42 exits the lens 36a and enters subsystem 8
1a exits as a collimated spatially filtered scattering probe beam P42A consisting of light beams P42A-1, -2, -3, -4.

As shown in FIG. 1a, the reflected reference beam R32B is transmitted by the beam splitter 100 as a reflected reference beam R32C partially composed of the light beams R32C-1, -2, -3, -4. . Reflected reference beam R32C enters subsystem 81a shown in FIG. 1i. The plane in FIG. 1i is orthogonal to the plane in FIG. 1a. In FIG. 1i, the reflected reference beam R32C enters the lens 26a,
It emerges as a reflected reference beam R32D consisting of light beams R32D-1, -2, -3, -4. The lens 26a transmits the reflected reference beam R32D to the pinhole 1 on the image plane 17a.
Focus on 8a. A part of the reflected reference beam R32D is a part of the light beams R42-1, -2,
Exits pinhole 18a as a spatially filtered reflected reference beam R42 consisting of -3, -4. The spatially filtered reflected reference beam R42 enters the lens 36a. The spatially filtered reflected reference beam R42 exits the lens 36a and is subsystemed as a collimated spatially filtered reflected reference beam R42A consisting of light beams R42A-1, -2, -3, -4. 81
Go out of a.

FIG. 1a shows that a spatially filtered scattering probe beam P42A is incident on a dispersive element 130a, preferably a reflective diffraction grating. Part of the spatially filtered scattering probe beam P42A is
In the plane of the figure, it is diffracted by the first dispersion detector element 130a as a scattered probe beam P42B. The scattered probe beam P42B is incident on a second dispersion detector element 130b, which is preferably a transmission diffraction grating. Part of the scattered probe beam P42B is located in the plane of FIG.
The wave number is filtered by 30b and diffracted as a spatially filtered scattering probe beam P42C. Beams P42B and P42C consist of a spectrum of optical frequency components and are therefore angularly dispersed in the plane of FIG.
FIG. 1a shows only the path of one frequency component of the beams P42B and P42C. The paths shown are typical. By illustrating only one frequency component of the beams P42B and P42C, one can indicate the important properties of the subsystem 84 for the wavenumber-filtered and spatially-filtered scattered probe beam P42C. It does not depart from the spirit or scope and does not introduce undue complexity to FIG. 1a and subsequent figures.

The wavenumber filtered and spatially filtered beam P42C is
Enter the subsystem 84 shown in FIG. The plane in FIG. 1j is orthogonal to the plane in FIG. 1a. As shown in FIG. 1j, the wavenumber-filtered and spatially-filtered beam P42C passes through a lens 66 having an optical axis aligned with the optical axis 3d of the subsystem 84 to form a light beam. P42D-1, -2, -3, -4
Exits as a wavenumber filtered and spatially filtered beam P42D consisting of The wavenumber-filtered and spatially-filtered beam P42D illustrated by a single optical frequency component is focused by a lens 66 onto a point image 48 on an image plane 47. The position of the point image 48 in the image plane 47, and thus the position of the point image 48 in the linear array of detector pinholes located in the image plane 47, is due to the distributed detector elements 130a and 130b. , Wave number filtered and spatially filtered depending on the optical frequency of the beam P42D. The portion of the light beam that passes through the linear array of detector pinholes is detected by a multi-pixel detector, preferably by a detector comprising a linear array of pixels, such as a linear array CCD.

FIG. 1a shows that a spatially filtered reflected reference beam R42A is incident on a dispersive detector element 130a. A portion of the spatially filtered reflected reference beam R42A is diffracted in the plane of FIG. 1a by the dispersive detector element 130a as a reflected reference beam R42B. The reflected reference beam R42B is incident on a second dispersive detector element 130b. A portion of the reflected reference beam R42B is wavenumber filtered in the plane of FIG. 1a by a second dispersive detector element 130b and diffracted as a spatially filtered reflected reference beam R42C. Beams R42B and R42C consist of a spectrum of optical frequency components and are therefore angularly dispersed in the plane of FIG. 1a, but FIG. 1a shows only the path of one frequency component of beams R42B and R42C. I have. The paths shown are typical. Beams R42B and R4
By showing only one frequency component of 2C, one can indicate the important properties of section 84 with respect to the wavenumber-filtered and spatially-filtered scattered probe beam R42C, from the spirit or scope of the present invention. It does not deviate and does not introduce undue complexity into FIG. 1a and subsequent figures.

The wave number filtered and spatially filtered reflected reference beam R42C
Enters the subsystem 84 shown in FIG. 1k. The plane in FIG. 1k is 1a
It is orthogonal to the plane of the figure. In FIG. 1k, a wave number filtered and spatially filtered reflected reference beam R42C passes through a lens 66 to a wave number filtered light beam R42D-1, -2, -3, -4. And exits as a spatially filtered reflected reference beam R42D. The wave number filtered and spatially filtered reflected reference beam R42D illustrated by only one optical frequency component in FIG.
Focused on 8. The position of the point image 48 in the image plane 47 and thus the image plane 47
Position of the point image 48 in a linear array of detector pinholes located in
Depends on the optical frequency of the wavenumber filtered and spatially filtered beam R42D. The portion of the light beam that passes through the linear array of detector pinholes is detected by multi-pixel detector 114.

In FIG. 11, a part of the light beam P22 (see FIG. 1d) is partially changed by the target material in the “out of focus” point image 58 on the out of focus image plane 57, depending on the target material.
The light is reflected and / or scattered as a background beam B52 composed of -3 and -4. The plane in FIG. 11 is orthogonal to the plane in FIG. 1a. The background beam B52 has an out-of-focus point image 5
The light diverges from 8 and enters the lens 46. As shown in FIG. 11, background beam B52 exits lens 46 as a substantially collimated background beam B52A consisting of light beams B52A-1, -2, -3, -4. Light beam B52A-1
, -2, -3, -4 are the phase shifters 24-4, 24-3, 24-2,
And light beams B52B-1, -2, -3, and -4, respectively. The light beams B52B-1, -2, -3, and -4 constitute a background beam B52B. The phase shifts introduced by phase shifters 24-1 and 24-3 are of equal value, which is π radian greater than the phase shifts introduced by phase shifters 24-2 and 24-4, The phase shift introduced by 24-4 is of equal value.

As shown in FIG. 1a, the background beam B52B is partially reflected by the beam splitter 100 as a background beam B52C composed of light beams B52C-1, -2, -3, -4. Background beam B52C enters subsystem 81a shown in FIG. 1m and exits through lens 26a as background beam B52D. The background beam B52D includes the light beams B52D-1, -2, -3, and -4. The plane in FIG. 1m is orthogonal to the plane in FIG. 1a. The background beam B52D is focused by the lens 26a on a point image 68 on an out-of-focus image plane 67 that is offset from the image plane 17a. The background beam B52D is out of focus at the image plane 17a, so that for any frequency component of the background beam B52D, only a small portion of the out-of-focus background beam B52D is transmitted by the pinhole 18a. This small portion of the out-of-focus background beam B52D is transmitted by the pinhole 18a as a spatially filtered background beam B62 consisting of the light beams B62-1, -2, -3, -4. Spatially filtered background beam B6
A portion of 2 enters lens 36a and exits as a substantially collimated spatially filtered background beam B62A consisting of light beams B62A-1, -2, -3, -4. Spatially filtered background beam B62A exits subsystem 81a as spatially filtered background beam B62A.

FIG. 1a shows that a spatially filtered background beam B62A is incident on a dispersive detector element 130a. A portion of the spatially filtered background beam B62A is diffracted as a background beam B62B by the dispersive detector element 130a in the plane of FIG. 1a. Background beam B62B
Are incident on a second dispersive detector element 130b. Background beam B62B
Are wave number filtered in the plane of FIG. 1a by a second dispersive detector element 130b and diffracted as a spatially filtered background beam B62C. Beams B62B and B62C consist of a spectrum of optical frequency components and are therefore angularly dispersed in the plane of FIG. 1a, but FIG. 1a shows only the path of one frequency component of beams B62B and B62C. I have. The wavenumber filtered and spatially filtered background beam B62C enters the subsystem 84 shown in FIG. 1n. In FIG. 1n, the wavenumber filtered and spatially filtered background beam B62C passes through lens 66,
Exits as a wavenumber filtered and spatially filtered background beam B62D. The wavenumber-filtered and spatially-filtered background beam B62D illustrated by only one optical frequency component in FIG.
Is focused on the point image 48 on the image plane 47. The position of the point image 48 in the image plane 47 depends on the optical frequency of the wavenumber-filtered and spatially-filtered background beam B62D. The portion of the light beam that passes through the linear array of detector pinholes is detected by multi-pixel detector 114.

For the wavenumber-filtered and spatially-filtered background beam B62D in the image plane 47 (see FIG. 1n), the intensity differences I1-I2 and I3-I4 as a result of the confocal interference system characteristics. Contains only the mutual interference terms between the complex amplitude of the wavenumber filtered and spatially filtered scattered background beam B62D and the complex amplitude of the wavenumber filtered and spatially filtered reflected reference beam R42D. Absent. However, wave number filtered and wave number filtered at the image plane 47 with the complex amplitude of the spatially filtered background beam B62D,
The magnitude of the cross-interference term with the complex amplitude of the spatially filtered reflected reference beam R42D is smaller than the corresponding cross-interference term in a conventional confocal interference microscope.
The comparison for each pixel greatly decreases.

The wavenumber-filtered and spatially-filtered focused scattering probe beam P42D and the wavenumber-filtered and spatially-filtered background beam B
In the general case where both 62D are present simultaneously, the intensity differences I ₁ -I ₂ and I _3-
I ₄ includes the difference between the complex amplitude of the wavenumber filtered and spatially filtered focused scattering probe beam P42D and the complex amplitude of the wavenumber filtered and spatially filtered reflected reference beam R42D. Mutual interference terms and the mutual interference between the complex amplitude of the wavenumber-filtered and spatially filtered background beam B62D and the complex amplitude of the wavenumber-filtered and spatially filtered reflected reference beam R42D There are two mutual interference terms. The mutual interference term between the complex amplitude of the wavenumber-filtered and spatially filtered background beam B62D and the complex amplitude of the wavenumber-filtered and spatially filtered reflected reference beam R42D is confocal interference The intensity difference I ₁ −
To offset the I ₂ and I ₃ -I _4.

[0171] Between the complex amplitude of the wavenumber-filtered and spatially filtered background beam B62D and the complex amplitude of the reflected reference beam R42D in the wavenumber-filtered and spatially filtered image plane 47. The mutual interference term indicates the background from the out-of-focus image. Comparing the device of the present invention with a prior art interference confocal microscope system, the wavenumber filtered and spatially filtered background beam B6
The mutual interference term between the 2D complex amplitude and the complex amplitude of the reflected reference beam R42D in the wavenumber-filtered and spatially filtered image plane 47 is reduced in magnitude in the image plane 47. The mutual interference between the complex amplitude of the wavenumber-filtered and spatially filtered focused scattering probe beam P42D and the complex amplitude of the wavenumber-filtered and spatially filtered reflected reference beam R42D The term size does not decrease substantially. Mutual interference term between the complex amplitude of wavenumber-filtered and spatially filtered background beam B62D and the complex amplitude of reflected reference beam R42D in wavenumber-filtered and spatially filtered image plane 47 In part because the beam amplitude decreases as the distance to the image plane increases. This property is the basis for reducing background in prior art confocal interference microscopes. However, in the device of the present invention, the complex amplitude of the wavenumber-filtered and spatially filtered background beam B62D and the complex amplitude of the reflected reference beam R42D in the wavenumber-filtered and spatially filtered image plane 47 are shown. The reduction in the magnitude of the cross-interference term between the amplitude is enhanced compared to that obtained with prior art confocal interference microscopes.

The magnitude reduction mentioned above is enhanced by providing phase shifters 14, 24 and 34. The phase shifters 14, 24 and 34 are the complex amplitudes of the wavenumber-filtered and spatially-filtered focused scattering probe beam P42D, the reflections in the wavenumber-filtered and spatially-filtered image plane 47. The spatial characteristics of the complex amplitude of the reference beam R42D and the complex amplitude of the wavenumber filtered and spatially filtered background beam B62D are varied at the focused image plane 47. The complex of the complex amplitude of the wavenumber-filtered and spatially filtered focused scattering probe beam P42D and the complex amplitude of the reflected reference beam R42D in the wavenumber-filtered and spatially filtered image plane 47 The spatial properties of the amplitudes are both phase shifters 14, 24 and 3
4, the changed spatial distribution of the complex amplitude in each image plane 47 is substantially the same. This feature distinguishes between the complex amplitude of the wave number filtered and spatially filtered focused scattering probe beam P42D and the complex amplitude of the wave number filtered and spatially filtered reflected reference beam R42D. A discussion of the sensitivity of the intensity differences I ₁ -I ₂ and I ₃ -I _{4 to} the interference terms has been described above.

However, at the image plane 47, the wavenumber filtered and spatially filtered complex amplitude of the background beam B62D, and the wavenumber filtered,
Each modified spatial distribution of the complex amplitude of the spatially filtered reflected reference beam R42D is distinctly different. The complex amplitude of the wavenumber-filtered and spatially-filtered reflected reference beam R42D is an antisymmetric function about the center of the wavenumber-filtered and spatially-filtered reflected reference beam R42D in the image plane 47. is there. In contrast, the wavenumber-filtered and spatially filtered background beam B62D, which is later wavenumber-filtered and interferes with the complex amplitude of the spatially-filtered reflected reference beam R42D, is the first m As shown, the complex amplitude is primarily associated with one of the light beams B52D-1, -2, -3, or B52D-4, which is generally wavenumber filtered at image plane 47 and spatially. Filtered reference beam R42
The space in the image of D shows only a relatively small relative change. Thus, in the image plane 47, the mutual difference between the complex amplitude of the wavenumber filtered and spatially filtered background beam B62D and the complex amplitude of the wavenumber filtered and spatially filtered reflected reference beam R42D. The spatial distribution of the interference terms is mainly composed of an antisymmetric distribution around the center of the wave number filtered and spatially filtered reflected reference beam R42D in the image plane 47.

The cross-interference term between the complex amplitude of the wavenumber filtered and spatially filtered background beam B62D and the complex amplitude of the wavenumber filtered and spatially filtered reflected reference beam R42D. , The contribution to the intensity values recorded by a single pixel of the detector 114 is integrated in the image plane 47 with the wave interference filtered and spatially filtered reflected reference beam R42D, the mutual interference term over the space of the image. It is. The integral of the antisymmetric function in a space section centered on the antisymmetric axis of this function is identically zero. Thus, from the mutual interference terms between the complex amplitude of the wavenumber-filtered and spatially filtered background beam B62D and the complex amplitude of the wavenumber-filtered and spatially filtered reflected reference beam R42D, The net contribution to the intensity value recorded by a single pixel of the detector 114 is greatly reduced over that obtained with prior art confocal interference microscopes.

In the image plane 47, between the complex amplitude of the wavenumber filtered and spatially filtered background beam B62D and the complex amplitude of the wavenumber filtered and spatially filtered reflected reference beam R42D. It is important to note that reducing the mutual interference term leads to a reduction in systematic as well as statistical errors. The reduced statistical error is due to the complex amplitude of the wavenumber-filtered and spatially-filtered background beam B62D at the image plane 47 and the wavenumber-filtered and spatially-filtered reflected reference beam. R42D
Reduces the number of photoelectrons generated at each pixel of the detector compared to the prior art. The statistical uncertainty of the integrated charge, and thus the statistical uncertainty of the output signal, is related to the square root of the integrated number of photoelectrons generated at each pixel of the detector, so that Statistical errors are greatly reduced in the apparatus of FIGS. 1a-1n.

Thus, the statistical error per point image of the image line section of the target material obtained with the apparatus of the present invention is compared to that obtained with the prior art confocal interference microscope in the same time interval. Substantially smaller for two reasons. The first reason is that in prior art confocal interference microscopes, an image line section had to be scanned in that time interval, corresponding to an array of intensity differences acquired simultaneously by the device of the present invention in the same time interval. This means that the time spent on each point image is reduced by the number of point images in the image line section in order to obtain an array of intensity differences. Thereby, the statistical accuracy of the image composed of the point images of the image line sections is higher in the device according to the invention than in the prior art confocal interference microscope with the independent point images of the image line sections. Is improved by a factor proportional to the square root of the number The basis for the second reason is that, as noted in the above paragraph, the wavenumber filtered and spatially filtered complex amplitude of the background beam B62D in the image plane 47 and the wavenumber filtered and spatially filtered The magnitude of the cross-interference terms between the complex amplitudes of the filtered reflected reference beam R42D is substantially reduced compared to that obtained for the corresponding cross-interference terms in a prior art confocal interference microscope. is there. These two reasons are due to the statistical error introduced by the amplitude of the out-of-focus image, and the apparatus of the present invention considered the statistical accuracy of the image of the line section of the target material acquired in the same time interval. This is the basis for the conclusion that in the case of prior art confocal interference microscopes there is a significant reduction compared to the statistical error introduced by the amplitude of the out-of-focus image.

The correction of the effects of out-of-focus images beyond the compensation achieved with the device of the first embodiment, ie of the systematic errors, is performed by computer and computer deconvolution, known to those skilled in the art, and later. A fourth equation set by (32a) and (32b),
Can be performed using an integral equation inversion method in which the integral equation is inverted according to the following equation.

The S / N ratio can also be adjusted as a function of the wavelength of the optical frequency component of the light source, for example to produce a wavelength independent S / N ratio in a first order approximation. In general,
The wavelength-filtered and spatially-filtered scattered probe beam P42D, normalized with the corresponding optical frequency component of the amplitude of the probe beam P22D prior to entry into the target material 112, becomes the probe beam P22 at the target material 112.
D and the wavelength dependence of the transmittance of the scattering probe beam P32,
Changes with wavelength due to changes in the numerical aperture of the probe lens 46 as the depth of the point image 28 into 12 increases. Also, the ratio of the amplitude of the wavelength-filtered and spatially-filtered scattered probe beam P42D to the amplitude of the wavelength-filtered and spatially-filtered background beam B62D is generally less than the target material 112. Decreases as the depth of the point image 28 increases. S /
The change in the N-ratio is generally the amplitude of the wavelength-filtered and spatially-filtered scattered probe beam P42D normalized to the corresponding optical frequency component of the amplitude of the probe beam P22D prior to entry into the target material 112. With the change of. The effect of these factors on the signal-to-noise ratio is due to the fact that the wavelength filters are placed in the reference mirror subsystem 83 and / or the probe beam subsystem 82, preferably in the reference mirror subsystem 83, and each at various wavelengths. Through the detector pinhole,
Wavelength-filtered and spatially-filtered scattering probe beam P42
D and a wavelength-filtered, spatially-filtered reflected reference beam R42
By configuring the transmittance of the wavelength filter to have a particular wavelength dependence such that the ratio of D is adjusted and / or optimized by a fourth equation (39) set later, in part. Can compensate.

In the detailed description of the first embodiment, the light beam P22C-1, -2, -3, -4
It has been noted that there is no net relative phase shift between any two of. This feature makes it possible to achieve the following goals stated in the detailed description of the first embodiment: the image plane 27 in the target material 112 and the image plane 37 in the reference mirror 120, The image planes 17a and 47, which are not substantially changed by the presence of the phase shifters 14 and 24 and the phase shifters 14 and 34, respectively, but are conjugate to the point image 28 on the target material 112 and the point image 38 on the reference mirror 120, respectively.
The goal is to generate a conjugate image of the pinhole 8 that produces a substantial change in the image at.

Further, by considering what happens when the phase shifter 14 is removed from the first embodiment, the correlation between the phase shifters 14, 24 and 34 can be obtained. In this case, the wave number filtered and spatially filtered reflected reference beam R42D substantially changes the spatial properties of the background beam B62D in the wave number filtered and spatially filtered image plane 47. Instead, it changes from an antisymmetric function to a symmetric function in the image plane 47. Thus, the complex amplitude of the wavenumber-filtered and spatially-filtered reflected reference beam R42D and the background beam B62 in the wavenumber-filtered and spatially-filtered image plane 47
The spatial distribution of the cross-interference terms with the complex amplitude of D is primarily a symmetric distribution about the center of the wavenumber filtered and spatially filtered reflected reference beam R42D in the image plane 47. Eggplant However, the integration of the symmetric function over a spatial interval about the axis of symmetry of the function is generally not zero, and the intensity values recorded by single-pixel detector 114 at image point 48 are conventionally There is virtually no reduction beyond the value achieved with the confocal interference microscope of the technology.

Although the above description relates to a particular focused image point 28 of a particular portion of the target material 112, the computer 118 locates another portion of the target material 112 at the focused image point 28 and the system A control signal 133 can be applied to the translator 116 so that a desired line, plane, or volume section of the material 112 can be “scanned”.
The desired line section, planar section, or volume section of the target material may cut or include one or more surfaces of the target material.

The level 1 identification in the first embodiment of the present invention is performed by distributing the impulse response functions of the imaging subsystem of the device of the present invention to the distributed detector elements 130a and 130a.
This is achieved by operating in a plane perpendicular to the plane defined by b. Level 1 type identification is also achieved in a variant of the first preferred embodiment, wherein the apparatus and electronic processing means of this variant are substantially the same as in the first preferred embodiment. Yes, the phase shifters 14, 24 and 34 are rotated by π / 2 radians around their respective optical axes. The reduction of the systematic effects of out-of-focus images in this variant of the first preferred embodiment is the same as in the first preferred embodiment. The statistical effect of out-of-focus images in this variant of the first preferred embodiment is also less than that achieved in prior art confocal interference microscopes, but generally with the device of the first preferred embodiment. Not as effective as achieved.

Referring now to FIGS. 2a-2f, FIG. 2a shows a light source subsystem 80a, a subsystem 81b, and a detector subsystem 84a preferably formed for an approximate slit confocal microscope. From the first group of embodiments and variants thereof, a second embodiment of the invention is shown schematically. 2a-2
In Figure f, like reference numerals have been used for like elements already described in connection with Figures 1a-1n. The changes in subsystem 80a shown in FIG. 2b have been made in the area of light source 10a. In this embodiment, the light source is preferably a broadband, spatially incoherent line light source, preferably a lamp filament or laser diode array. The modification also lies in the area of the pinhole 8 of the first embodiment, in which the pinhole is preferably a linear light source pinhole array 8a aligned with the image of the line light source 10a formed by the lens 6. It consists of. The modification of the subsystem 81b shown in FIGS. 2c and 2d is that the pinhole 18a in the subsystem 81a of the first embodiment is replaced by a linear array of spatial filter pinholes 18b in the subsystem 81b. is there. A modification of the subsystem 84a shown in FIGS. 2e and 2f is in the area of the detector 114, wherein a linear array of pinholes in the image plane 47 of the first embodiment is preferably detected in this example. The detector having a two-dimensional array of detector pinholes and having a linear array of pixels in the first embodiment, the detector 1 in this example preferably comprising a two-dimensional array of pixels
14a.

In FIG. 2b, the linear light source pinhole array 8a and light source 10a are aligned vertically with respect to the plane of FIG. 2b, the plane of FIG. 2b being orthogonal to the plane of FIG. 2a. ing. 2c and 2d, the linear array of spatial filter pinholes 18b is vertically aligned with the plane of FIGS. 2c and 2d,
The planes in FIGS. 2c and 2d are orthogonal to the plane in FIG. 2a. 2e and 2f, the two-dimensional array of detector pinholes and the two-dimensional array of detector pixels are aligned perpendicular to the plane of FIGS. 2e and 2f.

The remaining parts of the second embodiment shown in FIGS. 2a to 2f preferably describe the corresponding aspects of the first embodiment in the description of FIGS. 1a to 1n. Same as what you did.

The level 1 identification in the second embodiment of the present invention is performed by distributing the impulse response function of the imaging subsystem of the device of the present invention to the distributed detector elements 130a and 130a.
This is achieved by operating in a plane perpendicular to the plane defined by b. Level 1 type identification is also achieved in a first variant of the second preferred embodiment, wherein the device and the electronic processing means according to the first variant of the second preferred embodiment are substantially As in the second preferred embodiment, the phase shifter 14
, 24 and 34 are rotated about their respective optical axes by π / 2 radians.
The reduction of the systematic effects of out-of-focus images in the first variant of the second preferred embodiment is the same as in the second preferred embodiment. The statistical effects of out-of-focus images in the first variant of the second preferred embodiment are also less than those achieved in prior art confocal interference microscopes, but generally, of the second preferred embodiment. Not as effective as achieved with the device.

A second variant of the second preferred embodiment is described, in which the apparatus and the electronic processing means of the second variant are substantially the same as in the second preferred embodiment. The only difference is that the linear array of light source pinholes 8a and the spatial filter pinholes 18a in the second preferred embodiment are replaced by light source slits and spatial filter slits. The reduction of the systematic effects of out-of-focus images in the second variant of the second preferred embodiment is the same as that achieved in the second preferred embodiment of the present invention. The statistical effect of out-of-focus images in the second variant of the second preferred embodiment is also less than that achieved in prior art confocal interference microscopes, but generally, of the second preferred embodiment. Not as effective as achieved with the device.

As in the second preferred embodiment and the first variant of the second preferred embodiment, using a linear array of light source pinholes and a linear array of spatial pinholes instead of respective slits Creates the need for a limited scan of the target material to generate a two-dimensional representation of the section of the target material. The limited scan direction is the direction of the image of the linear array of light source pinholes in the target material.
Limited scanning occurs because of the pinhole spacing in the direction of the image of the linear array of light source pinholes in the target material. Furthermore, the high sensitivity to the wavenumber-filtered and spatially-filtered probe beam is such that the pinhole spacing in the direction of the image of the linear array of light source pinholes in the target material is later determined by the formula (
It is maintained when the condition indicated by 54) is met.

[0189] The number of limited scanning steps is determined by the ratio between the spacing between the images of two consecutive light source pinholes in the target material and the angular resolution of each imaging subsystem. In practice, the number of steps in a limited scan is significantly less than the number of pinholes in a linear array of light source pinholes and spatial filter pinholes. Thus, by using the second preferred embodiment with the light source pinhole and the spatial filter pinhole and the first variant of the second preferred embodiment, the two-dimensional representation of a section of the material of interest is substantially reduced. Can be obtained without scanning anything.

Reference is now made to FIGS. 3a to 31 where the paths of the reference and probe beams of the first preferred embodiment have been modified to improve and optimize the S / N ratio. Another first embodiment of the invention is shown from the first group of the above embodiments. The device and the electronic processing means of this third embodiment are substantially the same as in the first preferred embodiment, the first implementation being such that the ratio of the amplitudes of the reflected reference beam and the scattered probe beam can be adjusted. Optical means to reconfigure the interferometer in form have been added. The optical element of this third embodiment behaves similarly to the element similarly displayed in the first preferred embodiment, and the electronic processing means of the third embodiment is similarly displayed in the first preferred embodiment. An operation similar to the performed electronic operation is performed. The ratio of the amplitudes of the wave number filtered and spatially filtered reflected reference beam and the scattered probe beam is determined by the beam splitter 10 shown in FIGS. 3a-3l.
It is adjusted by changing the transmission / reflection coefficients of 0, 100a, and 100b.

As shown in FIGS. 3a to 3l, a third preferred embodiment of the present invention includes beam splitters 100, 100a and 100b, target materials 112,
Translator 116, reference mirror 120, distributed detector elements 130a and 130b
, And a detector 114. This configuration is known to those skilled in the art as one type of Michelson interferometer and is shown as a simple example. Known to those skilled in the art as a polarization Michelson interferometer, C.I. Zanoni,
Other forms of interferometers, such as those described in the article of ibid, are also shown in FIGS.
It can be incorporated into the figures, without departing much from the spirit and scope of the third preferred embodiment of the invention.

In the third preferred embodiment, the orientation of the plane in which the impulse response function of the imaging subsystem is manipulated is orthogonal to the plane of FIG. 3a. FIG. 3b shows, in schematic form, an embodiment of the subsystem 80 shown in FIG. 3a. For the third preferred embodiment, the light source 10 is preferably a point light source or a radiation source spatially incoherent over the surface of the light source, a laser or similar coherent or partially coherent radiation source, and preferably Is a polarized light source. Light source 10 emits an input beam 2 that is aligned with optical axis 3 of subsystem 80. 3b
As shown, the light beam 2 enters a focusing lens 6 and is focused on a pinhole 8 in an image plane 7. A plurality of light beams 12-1, 12-2, 12-3, 12-4
Is divergent from the pinhole 8 and the optical axis 3 of the subsystem 80
And enters a lens 16 having an optical axis aligned with. The light beam 12 is the light beam 1
The light exits the lens 16 and enters the phase shifter 14 as a collimated light beam 12A including 2A-1, 12A-2, 12A-3, and 12A-4. The phase shifter 14 includes rectangular phase shifters 14-1, 14-2, 14-3, and 14-4. These phase shifters are arranged such that their respective optical axes are parallel to the optical axis 3 of the subsystem 80. The number of phase shifters can be any suitable number 2 that is an integer.
m and m are preferred. The example shown in FIG. 3b is for the case where m = 2, where four phase shifters are sufficient to clearly show the relationships between the components of the device of the invention. Parallel light beams 12A-1, 12A-2, 12A-3, 12A-4
Pass through the phase shifters 14-1, 14-2, 14-3, and 14-4, respectively, and exit from the phase shifter 14 as light beams 12B-1, 12B-2, 12B-3, and 12B-4, respectively. These light beams constitute the light beam 12B. Each of phase shifters 14-2 and 14-4 introduces a phase shift of π radians greater than the phase shift introduced by each of phase shifters 14-1 and 14-3. The phase shifts introduced by the phase shifters 14-1 and 14-3 are the same.

In FIG. 3a, the light beam 12B exiting the subsystem 80 is partially split by the beam splitter 100a as a light beam P12B including the light beams P12B-1, P12B-2, P12B-3, and P12B-4. To Penetrate. Light beam P12B
Enters the subsystem 81a. In FIG. 3c, light beam P12B enters lens 26a, and light beams P12C-1, P12C-2, P12C-3, P
It emerges as a light beam P12C containing 12C-4. The lens 26a focuses the light beam P12C on the image point 18a on the focused image plane 17a. Light beam P12C
Are the light beams P22-1, P22-2, P22-3, and P22 from the point image 18a.
-4. Light beam P22 enters lens 36a whose optical axis is aligned with optical axis 3 of subsystem 81a. The light beam P22 is
Subsystem 81 exits lens 36a as a collimated light beam P22A including light beams P22A-1, P22A-2, P22A-3, and P22A-4.
Exit a.

As shown in FIG. 3a, the light beam P22A partially becomes the light beam P22B.
-1, P22B-2, P22B-3, and P22B-4 pass through the beam splitter 100 as a light beam P22B and enter the subsystem 82 shown in FIG. 3d. The plane in FIG. 3d is orthogonal to the plane in FIG. 3a.

In FIG. 3D, the light beam P22B is incident on a phase shifter 24 composed of elements 24-1, -2, -3, -4. The phase shifter 24 is composed of the same number of 2m elements as the phase shifter 14, and is indicated by m = 2 in FIG. 3d. The light beams P22B-1, -2, -3, -4 are respectively phase shifters 24-1, -2,
After passing through -3, -4, the light beam P22C emerges as a light beam P22C composed of light beams P22C-1, -2, -3, -4. The phase shifts introduced by phase shifters 24-1 and 24-3 are of equal value, which is π radians greater than the phase shifts introduced by either phase shifters 24-2 or 24-4, and
The values of the phase shift introduced by -2 and 24-4 are equal. Thus, there is no net relative phase shift between any two of the light beams P22C-1, -2, -3, -4. The light beam P22C passes through the probe lens 46 as a light beam P22D composed of the light beams P22D-1, -2, -3, and -4, and a line image centered on the point image 28 on the image plane 27 of the target material 112 is formed. Focused to form. The axis of this line image is substantially parallel to the optical axis 3 of the imaging subsystem 82. The length of the line image is determined by a combination of factors such as the depth of focus of the probe lens 46, chromatic aberration (both can be adjusted), and the optical bandwidth of the light source 10. This line section may cut one or more surfaces of the target material, or may rest on a surface with the target material. The optical axis of lens 46 is aligned with optical axis 3 of subsystem 82.

In FIG. 3a, the light beam 12B is partially split by the beam splitter 100a into light beams R12B-1, R12B-2, R12B-3, R12B-4.
Is reflected as a light beam R12B including This light beam R12B is the third light beam.
The subsystem 81c shown in FIG. The plane in FIG. 3e is parallel to the plane in FIG. 3a.

In FIG. 3e, the light beam R12B enters the lens 26C and the light beam R1
It emerges as a light beam R12C composed of 2C-1, -2, -3, -4. Light beam R12
B-1, -2, -3, and -4 are spatially separated in a plane orthogonal to the plane of FIG. 3e, but in the view shown in FIG. 3e they overlap and appear to be of the same extent. Lens 26
c has an optical axis aligned with the optical axis 3b of the subsystem 81c. The lens 26c is
The light beam R12C is focused on the point image 18c on the image plane 17c together with the plane mirror 120c. The light beam R12C is obtained from the point image 18c by using the light beams R22-1, -2,
It emerges as a light beam R22 composed of -3 and -4. Light beam R22-1, -2, -3,-
4 are spatially separated in a plane orthogonal to the plane of FIG. 3e, but in the view shown in FIG. Light beam R22 enters lens 36c having an optical axis aligned with optical axis 3c of subsystem 81c. Light beam R22 exits lens 36c and exits subsystem 81c as light beam R22A comprising light beams R22A-1, -2, -3, -4. Light beam R22A-1,-
2, -3, -4 are spatially separated in a plane orthogonal to the plane of FIG. 3e, but in the figure shown in FIG. 3e they overlap and appear to be of the same extent.

As shown in FIG. 3a, light beam R22A exits subsystem 81c before entering subsystem 83a. Subsystem 83a shown in FIG. 3f
Consists of a lens 56a, a reference mirror 120, a beam splitter 100b, and phase shifters 34, 34a and 44. The plane in FIG. 3f is parallel to the plane in FIG. 3a. The phase shifter 34 comprising the phase shifter elements 34-1, -2, -3, -4 and the phase shifter 34a comprising the phase shifter elements 34a-1, -2, -3, -4 are shown in FIG. They are shown rotated by π / 2 radians around the optical axes 3a and 3c, respectively. This is to facilitate the description and tracking of the light beams R22A, R22B, R22C, and R22D passing through the subsystem 83a without departing from the spirit and scope of the third embodiment of the present invention.
Accordingly, the light beam R22A composed of the light beams R22A-1, -2, -3, -4 and the light beam R22B composed of the light beams R22B-1, 2-2, -3, -4 are shown in FIG.
It is shown rotated by π / 2 radian about the optical axis 3c, and the light beam R22C-
Light beam R22C composed of 1, -2, -3, -4 and light beam R22D-1, 2-2,-
The light beam R22D composed of 3 and -4 is illustrated in FIG. 3f with a rotation of π / 2 radian about the optical axis 3a. In subsystem 83a, light beam R22
A is a phase shifter 34 including the same number of phase shifters 14 and 2m elements.
a. The light beam R22A passes through the phase shifter 34a as a light beam R22B. Light beam R22B is partially reflected as light beam R22C. The phase shifts introduced by phase shifters 34a-1 and 34a-3 are equal in value, which is π radians greater than the phase shifts introduced by either phase shifters 34a-2 or 34a-4. And the value of the phase shift introduced by 34a-4 is equal. Therefore, the light beams R22C-1, -2
, -3, -4, there is no net relative phase shift between them. The light beam R22C passes through the lens 56a as a light beam R22D. The light beam R22D is focused on the point image 38 on the image plane 37 of the reference mirror 120 by the lens 56a. The optical axis of lens 56a is aligned with optical axis 3a of subsystem 83a.

In FIG. 3g, a part of the light beam P22D is a point image 28 (see FIG. 3d).
Is reflected and / or scattered by the target material 112 at
Are composed of a plurality of light beams P32-1, -2, -3, -4. The plane in FIG. 3g is orthogonal to the plane in FIG. 3a. The scattered probe beam P32 diverges from the point image 28 on the image plane 27 and enters the lens 46. As shown in FIG. 3g,
The scattered probe beam P32 exits the lens 46 as a collimated scattered probe beam P32A consisting of light beams P32A-1, -2, -3, -4. The light beams P32A-1, -2, -3, -4 are respectively phase shifters 24-4, -3,-
2 and -1, and exit as light beams P32B-1, -2, -3, and -4, respectively. Light beams P32B-1, -2, -3, -4 constitute scattered probe beam P32B and exit subsystem 82. The phase shifts introduced by phase shifters 24-1 and 24-3 are equal in value, which is π radians greater than the phase shifts introduced by either phase shifters 24-2 or 24-4, and phase shifters 24-2 And the value of the phase shift introduced by 24-4 is equal.

In FIG. 3h, the light beam R22D is reflected by the reference mirror 120 (see FIG. 3f) as a reflected reference beam R32 composed of the light beams R32-1, -2, -3, -4. The subsystem 83a shown in FIG. 3h comprises a lens 56a, a reference mirror 120, a beam splitter 100b, and phase shifters 34, 34a, and 44. The phase shifter 34 comprising the phase shifter elements 34-1, -2, -3, -4 and the phase shifter 34a comprising the phase shifter elements 34a-1, -2, -3, -4 are shown in FIG. It is shown rotated by π / 2 radians around the optical axes 3a and 3c, respectively. This is to facilitate the description and tracking of the light beams R32, R32A, and R32B passing through the subsystem 83a without departing from the spirit and scope of the third embodiment of the present invention. Therefore, the light beam R32B composed of the light beams R32A and R32B-1, -2, -3, and -4
And the light beam R32C composed of the light beams R32C-1, -2, -3, and -4 is the third h
In the figure, the rotation is shown by π / 2 radians around the optical axis 3a. The plane in FIG. 3h is parallel to the plane in FIG. 3a. The reflected reference beam R32 diverges from the point image 38 on the image plane 37 and enters the lens 56a. As shown in FIG. 3h, the reflected reference beam R32 is converted to a lens 5 as a collimated light beam R32A.
Exit from 6a. The light beams R32A-1, -2, -3, -4 are firstly transmitted to the phase shifter 44.
, And then pass through the phase shifters 34-4, -3, -2, and -1 respectively.
The beams exit as light beams R32B-1, -2, -3, and -4, respectively. The phase shift introduced by phase shifter 44 is controlled by signal 132 from computer 118. The phase shifts introduced by phase shifters 34-1 and 34-3 are equal in value, which is π radians greater than the phase shifts introduced by either phase shifters 34-2 or 34-4, and phase shifters 34-2 And the value of the phase shift introduced by 34-4 is equal. Reflected reference beam R32B exits subsystem 83a.

In FIG. 3A, a part of the scattering probe beam P32B is divided by the beam splitter 100 into a plurality of light beams P3 constituting the scattering probe beam P32C.
It is reflected as 2C-1, -2, -3, -4. The scattered probe beam P32C enters the subsystem 81a shown in FIG. 3i. In FIG. 3i, the scattering probe beam P32C enters the lens 26a, and the light beams P32D-1, -2, -3, -4
As a scattered probe beam P32D. The plane in FIG. 3i is orthogonal to the plane in FIG. 3a. The optical axis of the lens 36a is aligned with the optical axis 3a of the subsystem 81a. The lens 26a focuses the scattered probe beam P32D on the spatial filter pinhole 18a on the image plane 17a. A part of the scattering probe beam P32D is transmitted from the spatial filter pinhole 18a to the light beams P42-1, -2, -3, -4.
As a spatially filtered scattered probe beam P42 consisting of The spatially filtered scattered probe beam P42 enters a lens 36a having an optical axis that is aligned with the optical axis 3a of subsystem 81a. The spatially filtered scattered probe beam P42 exits the lens 36a and forms a light beam P42A.
Exit subsystem 81a as a collimated spatially filtered scattered probe beam P42A consisting of -1, -2, -3, -4.

As shown in FIG. 3a, the reflected reference beam R32B is transmitted in part by the beam splitter 100 as a reflected reference beam R32C composed of light beams R32C-1, -2, -3, -4. You. Reflected reference beam R32C enters subsystem 81a shown in FIG. 3j. In FIG. 3j, the reflected reference beam R
32C enters the lens 26a and exits as a reflected reference beam R32D consisting of light beams R32D-1, -2, -3, -4. The lens 26a has a reflected reference beam R32D
Is focused on the spatial filter pinhole 18a on the image plane 17a. A portion of the reflected reference beam R32D is converted to a spatially filtered pinhole 18a as a spatially filtered reflected reference beam R42 consisting of light beams R42-1, -2, -3, -4.
Exit. The spatially filtered reflected reference beam R42 enters the lens 36a. The spatially filtered reflected reference beam R42 exits lens 36a and is subsystemed as a collimated spatially filtered reflected reference beam R42A consisting of light beams R42A-1, -2, -3, -4. Exit 81a.

FIG. 3a shows that a spatially filtered scattered probe beam P42A is incident on a dispersive element 130a, preferably a reflective diffraction grating. Part of the spatially filtered scattering probe beam P42A
In the plane of the figure, it is diffracted by the dispersive detector element 130a as a scattered probe beam P42B. The scattered probe beam P42B is incident on a second dispersive detector beam element 130b, preferably a transmission grating. A portion of the scattered probe beam P42B is diffracted in the plane of FIG. 3a by a second dispersive detector beam element 130b as a wavenumber filtered and spatially filtered scattered probe beam P42C. You. Beam P4
2B and P42C consist of a spectrum of optical frequency components and are therefore angularly dispersed in the plane of FIG. 3a, but FIG. 3a shows only the path of one frequency component of beams P42B and P42C. I have. The paths shown are typical. By showing only one frequency component of the beams P42B and P42C,
Wave number filtered and spatially filtered scattering probe beam P42
Significant properties of subsystem 84 for C can be displayed without departing from the spirit or scope of the present invention and without introducing undue complexity to FIG. 3a and subsequent figures.

[0204] The wavenumber filtered and spatially filtered beam P42C is
The subsystem 84 shown in FIG. The plane in FIG. 3k is orthogonal to the plane in FIG. 3a. As shown in FIG. 3k, the wavenumber-filtered and spatially-filtered beam P42C passes through a lens 66 having an optical axis aligned with the optical axis 3d of subsystem 84 to form a light beam. P42D-1, -2, -3, -4
Exits as a wavenumber filtered and spatially filtered beam P42D consisting of The wavenumber-filtered and spatially-filtered beam P42D illustrated by a single optical frequency component is focused by a lens 66 onto a point image 48 on an image plane 47. The position of the point image 48 in the image plane 47, and thus the position of the point image 48 in the linear array of detector pinholes located in the image plane 47, is due to the distributed detector elements 130a and 130b. , Wave number filtered and spatially filtered depending on the optical frequency of the beam P42D. The portion of the light beam that passes through the linear array of detector pinholes is detected by detector 114, preferably by a detector comprising a linear array of pixels, such as a linear array CCD.

[0205] FIG. 3a shows that a spatially filtered reflected reference beam R42A is incident on a dispersive detector element 130a. A portion of the spatially filtered reflected reference beam R42A is diffracted in the plane of FIG. 3a by the dispersive detector element 130a as a reflected reference beam R42B. The reflected reference beam R42B is incident on a second dispersive detector element 130b. A portion of the reflected reference beam R42B is wavenumber filtered by the second dispersive detector element 130b in the plane of FIG. 3a and diffracted as a spatially filtered reflected reference beam R42C. Beams R42B and R42C consist of a spectrum of optical frequency components and are therefore angularly dispersed in the plane of FIG. 3a, but FIG. 3a shows only the path of one frequency component of beams R42B and R42C. I have. The paths shown are typical. By only showing one frequency component of the beams R42B and R42C, it is filtered wave number,
Section 84 for spatially filtered scattered probe beam R42C
Can be displayed without departing from the spirit or scope of the present invention and without introducing undue complexity to FIGS. 1a and subsequent figures.

A wave number filtered and spatially filtered reflected reference beam R42C
Enters the subsystem 84 shown in FIG. The plane in FIG.
It is orthogonal to the plane of the figure. In FIG. 31 the wave number filtered and spatially filtered reflected reference beam R42C passes through lens 66 and is wave number filtered consisting of light beams R42D-1, -2, -3 and -4. And exits as a spatially filtered reflected reference beam R42D. A wavenumber-filtered and spatially-filtered reflected reference beam R42D, illustrated by only one optical frequency component in FIG.
Focused on 8. The position of the point image 48 in the image plane 47 and thus the image plane 47
Position of the point image 48 in a linear array of detector pinholes located in
Is a wave number filtered and spatially filtered reflected reference beam R42D
Optical frequency. The portion of the light beam that passes through the linear array of detector pinholes is detected by detector 114.

The remainder of the third embodiment shown in FIGS. 3a to 31 is preferably
It is the same as the corresponding aspect of the first preferred embodiment described in FIGS. 1a to 1n and will not be described again.

The level 1 identification in the third preferred embodiment of the present invention is to perform the impulse response function of the imaging subsystem of the device of the present invention in a plane orthogonal to the plane defined by the distributed detector elements 130a and 130b. Is achieved by operating with Level 1 type identification is also achieved in a variant of the third preferred embodiment, wherein the equipment and electronic processing means according to that variant are substantially the same as in the third preferred embodiment. Yes, the phase shifters 14, 24 and 34 are rotated by π / 2 radians around their respective optical axes. The remainder of this variant of the third embodiment is preferably the same as that described in the description of the variant of the first preferred embodiment of the invention.

Next, description will be made with reference to FIGS. 4A to 4F. 4a to 4f show in schematic form a first embodiment of the group to a fourth embodiment of the invention, in which a light source subsystem 80a, a subsystem 81b and a detector subsystem are shown. System 84a is preferably configured for an approximate slit confocal microscope. 4a-4f, like elements described previously in connection with FIGS. 3a-3l have been given the same reference numerals. A modification of the subsystem 80a shown in FIG. 4b lies in the area of the light source 10a, which in this embodiment is preferably a broadband, spatially incoherent line light source, preferably a lamp filament or laser diode. An array. The modification is also in the area of the pinhole 8 of the third embodiment, in which it is preferably a linear light source pinhole array 8a that is aligned with the image of the line light source 10a formed by the lens 6. It is composed of The modification in subsystem 81b shown in FIGS. 4c and 4d replaces pinhole 18a in subsystem 81a of the third embodiment with a linear array 18b of spatial filter pinholes in subsystem 81b. It is in. The change in the subsystem 84a shown in FIGS. 4e and 4f is in the area of the detector 114a, and a linear array of pinholes in the image plane 47 of the third embodiment is preferably used in this embodiment. Is a two-dimensional detector pinhole, and the detector 114 having a linear array of pixels of the third embodiment is in this embodiment a detector 114a, which preferably comprises a two-dimensional array of pixels. .

In FIG. 4b, the linear array 8a of light source pinholes and the light source
The plane in FIG. 4b is orthogonal to the plane in FIG. 4a, aligned perpendicular to the plane in FIG. 4c and 4d, the linear array 18b of spatial filter pinholes is aligned perpendicular to the plane of FIGS. 4c and 4d, and
The plane in the figure is orthogonal to the plane in FIG. 4a. 4e and 4f, the two-dimensional array of detector pinholes and the two-dimensional array of detector pixels are aligned perpendicular to the plane of FIGS. 4e and 4f.

The remainder of the fourth embodiment shown in FIGS. 4a to 4f is preferably
It is the same as the corresponding aspect of the third preferred embodiment described in FIGS. 3a to 31 and will not be described again.

The level 1 identification of the fourth embodiment of the present invention is to manipulate the impulse response function of the imaging subsystem of the device according to the invention in a plane perpendicular to the plane defined by the dispersive detector elements 130a and 130b. It is realized by. Level 1 type identification can also be realized in the first modification of the fourth embodiment, and here, the device and the electronic processing means of the first modification are the second modification.
Substantially the same as in the fourth embodiment, the phase shifters 14, 24, and 34 are rotated by π / 2 radians about their respective optical axes. The remainder of the first modification of the fourth embodiment is the second modification of the present invention.
Desirably, the description is the same as that for the corresponding aspect of the first modification of the embodiment.

A second modification of the fourth embodiment will be described. Here, the device and the electronic processing means of the second modification are substantially the same as those of the fourth embodiment. Source pinhole 8a
The linear array and the spatial filter pinhole 18a are replaced with a source slit and a spatial filter slit. The remainder of the second modification of the fourth embodiment is the fourth modification of the present invention.
Preferably, it is the same as the description of the corresponding aspects of the embodiment.

The reduction of the systematic effect of the out-of-focus image of the second modification of the fourth embodiment is substantially the same as that realized by the prior art slit confocal interference microscope. However, the fourth
Although the statistical effect due to the out-of-focus image of the second modification of the embodiment is lower than that realized by the slit confocal interference microscope of the prior art, in general, the fourth embodiment and the first modification of the fourth embodiment. It is not as effective as can be achieved with a device.

The use of a linear array of source pinholes and a linear array of spatial pinholes instead of the respective slits as in the fourth embodiment and the first modification of the fourth embodiment is based on the cross section of the target material. Generates a limited scanning requirement of the target material to produce a two-dimensional representation. The direction of the restrictive scan is the direction of the image of the linear array of source pinholes of the material of interest. Restrictive scanning occurs because of the spacing between pinholes in the direction of the image of the linear array of source pinholes of the material of interest. Further, when the distance between the pinholes in the direction of the image of the linear array of source pinholes of the target material matches the condition described in equation (54), the scattering probe is wavenumber filtered and spatially filtered. Maintain high sensitivity to the beam.

The number of limited scan steps is determined by the ratio between the spacing between two successive source pinhole images of the target material and the angular resolution of the respective imaging subsystem.
In practice, the number of limiting scan steps is significantly less than the number of pinholes in a linear array of source and spatial filter pinholes. Therefore, by using the device of the fourth embodiment and the first modified example of the fourth embodiment with a linear array of the source pinholes and the spatial filter pinholes, the two-dimensional representation of the cross section of the target material is substantially reduced. Can be obtained without scanning.

In the description of the embodiment and the variants of the five groups of embodiments, the amplitude and the phase of the complex amplitude of the scattered probe beam scattered and / or reflected on the target material are obtained by the embodiment and its variants, respectively. It is written. In each of the embodiments and variants thereof, the statistical error and the systematic error greatly reduced in the determination of the complex amplitude of the scattered probe beam result in the maximum density data that can be stored and retrieved from the optical disk recording medium. In a related property, the recording medium is the target material.

The format of the data stored in the memory site is generally a binary that can use one bit. Reduced statistical and systematic errors in the embodiment and variants of the five-group embodiment. Increased S / N ratio enabled by the above property increases the maximum data density that can be stored on optical disk recording media. it can. The data stored in the memory site can be expressed in the form of (base N) x (base M), where base N is the number N of amplitude windows that compare the amplitude of complex amplitude, and base M is the number of phase windows that compare the phase of complex amplitude. It is several M.

In a variation of the embodiment and the five groups of embodiments, the amplitude of the complex amplitude is processed by a series of N window comparator electronic processors to determine which N window has the amplitude. Similarly, the complex amplitude phase is processed by a series of M window comparator electronic processors to determine which M window has the phase. The values of N and M that can be used are determined by factors such as the S / N ratio realization and the required processing time. Using one of the five groups of embodiments, the increase in maximum data density stored in optical memory is proportional to the NxM product.

The fifth embodiment of the present invention, which is presently preferred from the second group of embodiments, has many elements that perform functions similar to the same numbered elements of the first embodiment of the first group of embodiments. . In the confocal microscope system shown in FIG.1a, as shown in FIG.1aa, subsystem 82 into subsystem 82aa, dispersive elements 130c and 130d and subsystem 85,
Subsystem 83 is replaced with subsystem 83aa, mirror 120a, and subsystem 95 to provide a fifth embodiment of the present invention. In the fifth embodiment, the beam splitter 100, the target material 112,
, A translator 116, a reflector 120, a dispersive probe beam element 130c and 130d, a dispersive detector element 130a and 130b, and a Michelson interferometer consisting of a detector 114.

As shown in FIG. 1aa, the light beam 22A is
Partially transmitted as a light beam P22B containing 22B-1, -2, -3, -4 and enters subsystem 82aa shown in FIG. 1d.

In FIG. 1aa, the light beam P22B impinges on the phase shifter 24 including the phase shifters 24-1, -2, -3 and -4. The plane in FIG. 1ab is orthogonal to the plane in FIG. 1aa. Phase shifter 24
Is composed of the same number of 2m elements as the phase shifter 14, and is indicated by m = 2 in FIG. 1ab. Light beams P22B-1, -2, -3, -4 pass through phase shifters 24-1, -2, -3, -4, respectively, and light beams P22C-1, -2, -3, -4, respectively. Includes a light beam P22C. The values of the phase shifts by phase shifters 24-1 and 24-3 are equal, π radians greater than the phase shift introduced by phase shifters 24-2 or 24-4, and the phase introduced by phase shifters 24-2 and 24-4. The shift values are equal.

The phase shifters 14-1 and 24-1, 14-2 and 24-2, 14-3 and 24-3, 14-
The sum of the phase shifts generated by each set of 4 and 24-4 is π radians. Thus, there is no net relative phase shift between any two of the light beams P22C-1, -2, -3, -4. The light beam P22C is a light beam including the light beams P22D-1, -2, -3, -4 focused on the first intermediate probe beam spot at the point image 18 on the in-focus image plane 17.
The light passes through the lens 26 as P22D. The light beam P22D includes the light beams P32-1, -2, -3,
Exits point image 18 as light beam P32 containing −4. Light beam P32 is connected to subsystem 8
The light enters a lens 36 having an optical axis aligned with the optical axis 3 of 2aa. The light beam P32 is a lens as a collimated light beam P22A including the light beams P32A-1, -2, -3, -4.
Exit 36 and exit subsystem 82aa.

In FIG. 1aa, the probe beam P32A impinges on a third dispersive element, the dispersive probe beam element 130c, which is preferably a transmission diffraction grating. Probe beam
A part of P32A is the light beam P32B-1, -2, -3, respectively by the third dispersive element 130c.
The light is diffracted in the plane of FIG. 1aa as the probe beam P32B including −4. Probe beam
P32B corresponds to the fourth dispersive element, dispersive probe beam element 130d, which is preferably a transmission diffraction grating. Part of the probe beam P32B is the fourth dispersive element 130d
Is diffracted in the plane of FIG. 1aa as a probe beam P32C including the light beams P32C-1, -2, -3 and -4, respectively. The probe beams P32B and P32C are composed of spectra of optical frequency components and are dispersed at an angle in the plane of FIG. 1aa, but only one frequency component of the probe beams P32B and P32C is shown in FIG. 1aa. The paths shown are representative. By showing only one path for the optical frequency components of the probe beams P32B and P32C, the important characteristics of the subsystem 85 shown in FIG. And subsequent drawings without introducing undue complexity.

In FIG. 1ac, probe beam P32C enters subsystem 85 and passes through lens 46 to form a probe beam P32D that includes light beams P32D-1, -2, -3, and -4, respectively. The probe beam P32D is focused by the lens 46 to form a line image on the in-focus image plane 27 of the target material 112, thereby illuminating the target material 112. The line image on the in-focus image plane 27 includes a point image 28. The axis of the line image is substantially orthogonal to the optical axis 3a of the imaging subsystem 85. The length of the line image is determined by a combination of factors such as the focal length of the lens 46 and the dispersive power of the dispersive probe beam elements 130c and 130d, both of which are adjustable, and the optical bandwidth of the source 10. The line portion can cut one or more surfaces of the target material or lie on the surface of the target material. The optical axis of lens 46 is aligned with optical axis 3a of subsystem 85.

In FIG. 1aa, the light beam 22A is a light beam R2 including the light beams R22B-1, −2, −3, and −4.
Partially reflected by the beam splitter 100 as 2B. The light beam R22B is shown in FIG.
The subsystem 83aa indicated by ad enters. The plane of FIG. 1ad is orthogonal to the plane of FIG. 1aa.
As shown in FIG. 1ad, the light beam R22B impinges on the phase shifter 34 including the phase shifters 34-1, -2, -3, -4. The phase shifter 34 includes the same number of 2m elements as the phase shifter 14, and is indicated by m = 2 in FIG. 1ad. Each of the light beams R22B is a phase shifter 3
After passing through 4, the light passes through the phase shifter 44 and exits as a light beam R22C including the light beams R22C-1, -2, -3, and -4. The phase shift introduced by phase shifter 44 is controlled by signal 132 from computer 118.

The values of the phase shift introduced by the phase shifters 34-1 and 34-3 are equal,
The phase shift introduced by the phase shifters 34-2 or 34-4 is π radians greater, and the values of the phase shifts introduced by the phase shifters 34-2 and 34-4 are equal. Thus, there is no net relative phase shift between any two of the light beams R22C-1, -2, -3, -4. The light beam R22C passes through the lens 56 as a light beam R22D including the light beams R22D-1, -2, -3, and -4. The light beam R22D is focused by the lens 56 on the first intermediate reference beam spot at the point image 38 on the in-focus image plane 37. Lens 56
Is aligned with the optical axis 3b of the subsystem 83. The reference beam R22D is the light R2
The point image 38 exits the intermediate reference beam spot as a reference beam R32 containing 2D-1, -2, -3, -4. Reference beam R32 enters lens 66 having an optical axis aligned with optical axis 3b of subsystem 83aa. The reference beam R32 is a light beam R32A-1,
Exits lens 66 and exits subsystem 83aa as collimated reference beam R32A containing 2, -3, -4.

In FIG. 1aa, the reference beam R32A is reflected by the mirror 120a, and the light beams R32B-1 and −32, respectively.
Shown as being directed to subsystem 95 as a reference beam R32B containing 2, -3, -4. In FIG. 1ae, reference beam R32B passes through lens 76 as reference beam R32C including light beams R32C-1, -2, -3 and -4, respectively. The reference beam R32C is focused by the lens 76 on the reference mirror 120 to the point image 48 on the in-focus image plane 47. The optical axis of lens 76 is aligned with optical axis 3c of subsystem 95.

In FIG. 1af, a part of the probe beam P32D (see FIG. 1ac) is changed to the light beams P42-1 and -2.
, -3, -4, reflected and / or scattered by the illuminated target material in the line image area of the in-focus image plane 27 as a scattered probe beam P42. The scattered probe beam P 42 branches off the line image on the in-focus image plane 27 and enters the lens 46. As shown in FIG. 1af, the scattered probe beam P42 is a light beam P42A-1, -2, -3,-
Exiting lens 46 exits subsystem 85 as a collimated scattered probe beam P42A containing 4.

As shown in FIG. 1aa, the scattered probe beam P42A is a fourth dispersive probe beam element.
It corresponds to 130d. A part of the scattering probe beam P42A is a light beam P42B-1, respectively.
Dispersive probe beam element 1 as scattered probe beam P42B including -2, -3, -4
Diffracted by 30d in the plane of FIG. 1aa. The scattered probe beam P42B impinges on the third dispersive probe beam element 130c. A part of the scattering probe beam P42B is diffracted in the plane of FIG. 1aa as the scattering probe beam P42C including the light beams P42C-1, -2, -3, and -4, respectively. Scattering probe beams P42B and P42C consist of spectra of optical frequency components and are dispersed at an angle in the plane of FIG.
The path of only one frequency component of B and P42C is shown in FIG. 1aa. Scattering probe beam P
The optical frequencies of the component paths of 42B and P42C are the same as the component paths of the probe beams P32B and P32C shown in FIG. 1aa.

The scattered probe beam P42C enters the subsystem 82aa (see FIG. 1aa) shown in FIG. 1ag. In FIG. 1ag, the scattered probe beam P42D enters the lens 36, where P42D-1
, -2, -3, -4. The lens 36 has a scattered probe beam at the intermediate scattered probe beam spot at the point image 18 on the in-focus image plane 17.
Focus P42D. Although only the path of one optical frequency component of the scattering probe beam P42D is shown in FIG. 1ag, the point images of all the optical frequency components of the scattering probe beam P42D are the same as those schematically shown in FIG. Lens 36, dispersive probe beam elements 130c and 130d, lens 46, target material 112 are confocal imaging systems,
The point image 18 is a conjugate point image of the entire spectrum of the optical frequency component of the beam P32.

Continuing with FIG. 1ag, the scattered probe beam P42D has the light beams P52-1, -2,
The point image 18 exits as a scattering probe beam P52 including −3 and −4. The scattered probe beam P52 enters the lens 26, is collimated, and the light beams P52A-1 and -52, respectively.
, -3, -4 are formed. Light beam P52A-1, -2,
−3 and −4 pass through the phase shifters 24-4, −3, −2 and −1, respectively, and exit as light beams P52b-1, −2, −3 and −4, respectively. Light beams P32B-1, -2, -3, -4 consist of scattered probe beam P52B exiting subsystem 82aa. The value of the phase shift introduced by the phase shifters 24-1 and 24-3 is equal, π radians greater than the phase shift introduced by the phase shifters 24-2 or 24-4, and
The values of the phase shift introduced by −2 and 24-4 are equal.

In FIG. 1ah, the reference beam R32D (see FIG. 1ae) is a light beam R42-1, -2, -3, respectively.
-4 are reflected by the reference mirror 120 as a reflected reference beam R42. The reflected reference beam R42 branches off from the point image 48 on the in-focus image plane 47 and enters the lens 76. Figure 1
As shown in ah, the reflected reference beam R42 is a light beam R42A-1, -2, -3,-
Exiting lens 76 is collimated as a reflected reference beam R42A containing four.

In FIG. 1aa, the reflected reference beam R42A is reflected by the mirror 120a, and the respective light beams R42B-1
, -2, -3, -4, as reflected reference beam R42B to subsystem 83aa. In FIG. 1ai, the reflected reference beam R42B is a light beam R42C-1, -2, -3, -4, respectively.
And passes through the lens 66 as a reflected reference beam R42C. The reflected reference beam R42C is focused by the lens 66 at the point image 38 on the in-focus image plane 37 to the intermediate reflected reference beam image spot. The reflected reference beam R42C is the light beam R52-1, -2, -3, -4, respectively.
Exits the intermediate reflected reference beam spot at the point image 38 as a reference beam R52 containing The reference beam R52 enters the lens 56 and exits the lens 56 as a reference beam R52A including light beams R52A-1, -2, -3, -4, respectively. As shown in FIG. 1ai, the reflected reference beam R52 exits the lens 56 as a collimated reflected reference beam R52A including light beams R52A-1, -2, -3, -4, respectively. The light beams R52A-1, -2, -3, -4 first pass through the phase shifter 44, and then pass through the phase shifters 34-4, -3, -2, -1 respectively, and the light beams R32B-1 respectively. , -2, -3, -4 reflected reference beam R32B
Get out as. The phase shift introduced by phase shifter 44 is controlled by signal 132 from computer 118. The values of the phase shifts by phase shifters 34-1 and 34-3 are equal, π radians greater than the phase shifts introduced by phase shifters 34-2 or 34-4, and the phase introduced by phase shifters 34-2 and 34-4. The shift values are equal.
Light beams R32B-1, -2, -3, -4, which make up light beam R32B, exit subsystem 83aa.

The remaining description of the fifth embodiment is the same as that of the first embodiment. Wavelength-filtered and spatially-filtered scattering probe beam P42D
And the mutual interference term between the complex amplitude of the first embodiment and the complex amplitude of the spatially filtered reflected reference beam R42D of the first embodiment, and wavenumber filtered,
The mutual interference term between the complex amplitude of the spatially filtered scattered probe beam P62D and the complex amplitude of the wavenumber filtered and spatially filtered reflected reference beam R62D of the fifth embodiment includes the target material 112. The information about the two substantially orthogonal line portions is included, and the point images of each line portion are acquired at the same time. For the first embodiment, the line portion of the target material 112 is substantially parallel to the optical axis 3 of the subsystem 82,
For the five embodiment, the line portion of the target material 112 is substantially perpendicular to the optical axis 3a of the subsystem 85.

[0236] The level 1 identification of the fifth embodiment of the present invention is based on the distributed probe beam elements 130c and 13c.
This is achieved by manipulating the impulse response function of the imaging subsystem of the device according to the invention in a plane perpendicular to the plane defined by Od and the dispersive detector elements 130a and 130b. Level 1 type identification can also be realized in a first modification of the fifth embodiment, where the apparatus and electronic processing means of the modification are substantially the same as in the fifth embodiment, and the phase shifters 14, 24, and Rotate 34 around each optical axis by π / 2 radians.
The reduction of the systematic effect of the out-of-focus image of the modification of the fifth embodiment is the same as that of the fifth embodiment. The statistical effect of the out-of-focus image of the modification of the fifth embodiment is also lower than that realized by the prior art confocal interference microscope, but is generally not as effective as that realized by the device of the fifth embodiment.

This sixth embodiment of the invention from the second group of embodiments has many elements that perform similar functions as the same numbered elements of the second embodiment from the first group of embodiments, The sixth embodiment is configured almost for a slit confocal microscope. In the confocal microscope system shown in FIG.
Substituting 3aa, mirror 120a, and subsystem 95 provides a sixth embodiment of the present invention. The sixth embodiment includes a Michelson interferometer consisting of a beam splitter 100, a target material 112, a translator 116, a reference mirror 120, dispersive probe beam elements 130c and 130d, dispersive detector elements 130a and 130b, and a detector 114a. .

The rest of the description of the sixth embodiment is the same as the corresponding parts of the description of the second and fifth embodiments. Wavelength-filtered and spatially-filtered scattering probe beam P42D
A mutual interference term between the complex amplitude of the second embodiment and the complex amplitude of the spatially filtered reflected reference beam R42D of the second embodiment, and wavenumber filtered;
The mutual interference term between the complex amplitude of the spatially filtered scattered probe beam P62D and the complex amplitude of the wave number filtered and spatially filtered reflected reference beam R62D of the sixth embodiment includes the target material 112. The information about the two substantially orthogonal two-dimensional portions is included, and the point images of each two-dimensional portion are acquired simultaneously. No.
For two embodiments, the normal to the two-dimensional portion of the target material 112 is the optical axis of subsystem 82.
Substantially orthogonal to 3, and for the sixth embodiment, the normal to the two-dimensional portion of the target material 112 is substantially parallel to the optical axis 3a of the subsystem 85.

From the second group of embodiments to the present seventh embodiment of the present invention, there are many elements that perform functions similar to the same numbered elements of the third embodiment of the first group of embodiments. In the confocal microscope system shown in FIG.3a, as shown in FIG.3aa, subsystem 82 is subsystem 82aa, dispersive elements 130c and 130d and subsystem 85, subsystem 83a is subsystem 83ab, mirror 120a, The system 95 is replaced with the seventh embodiment of the present invention.
Examples are provided. The seventh embodiment includes a Michelson interferometer consisting of a beam splitter 100, a target material 112, a translator 116, a reflector 120, dispersive probe beam elements 130c and 130d, dispersive detector elements 130a and 130b, and a detector 114a. .

The rest of the description of the seventh embodiment is the same as the corresponding portions of the description of the third and sixth embodiments. Wavelength-filtered and spatially-filtered scattering probe beam P42D
And the mutual interference term between the complex amplitude of the third embodiment and the complex amplitude of the spatially filtered reflected reference beam R42D of the third embodiment,
The mutual interference term between the complex amplitude of the spatially filtered scattered probe beam P62D and the complex amplitude of the wavenumber filtered and spatially filtered reflected reference beam R62D of the seventh embodiment includes the target material 112. The information about the two substantially orthogonal line portions is included, and the point images of each line portion are acquired at the same time. For the third embodiment, the line portion of the target material 112 is substantially parallel to the optical axis 3 of the subsystem 82,
For the seven embodiments, the line portion of the target material 112 is substantially perpendicular to the optical axis 3a of the subsystem 85.

This eighth embodiment of the invention from the second group of embodiments has many elements that perform similar functions as the same numbered elements of the fourth embodiment from the first group of embodiments. Figure 4a
In the confocal microscope system shown in FIG. 4, the subsystem 82 is replaced by the subsystem 82aa, the dispersive elements 130c and 130d, and the subsystem 85, and as shown in FIG. 95 provides an eighth embodiment of the present invention. In the eighth embodiment, the beam splitter 100, the target material 112
, A translator 116, a reference mirror 120, a dispersive probe beam element 130c and 130d, a dispersive detector element 130a and 130b, and a Michelson interferometer comprising a detector 114a.

The description of the other portions of the eighth embodiment is the same as that of the corresponding portions of the fourth and seventh embodiments. A cross-interference term between the complex amplitude of the wavenumber-filtered and spatially-filtered scattered probe beam P42D of Example 4 and the complex amplitude of the wavenumber-filtered and spatially-filtered reflected reference beam R42D, and The mutual interference term between the complex amplitude of the wavenumber-filtered and spatially filtered scattered probe beam P62D of Example 8 and the complex amplitude of the wavenumber-filtered and spatially filtered reflected reference beam R62D is the target material It contains information about 112 two substantially orthogonal two-dimensional regions. Note that the image points of each two-dimensional region are collected simultaneously. Example 4
Then, the normal of the two-dimensional region of the target material 112 and the optical axis 3 of the subsystem 82 are substantially orthogonal, and in the eighth embodiment, the normal of the two-dimensional region of the target material 112 and the optical axis of the subsystem 85 3a
Are substantially orthogonal.

The preferred embodiments 9, 10, 11, 12 and their variants in the third group of this embodiment, except that the phase shifters 14, 24, 34, 34a are omitted. , And are composed of components and subsystems similar to those of the first, second, third, and fourth embodiments. The description of the third group of embodiments and other parts related to its variants is in the group of the first embodiment, except for the level of statistical accuracy of the images obtained in a given time. This is the same as the description part corresponding to the embodiment and the modification.

The statistical accuracy of the images obtained in a given time in the embodiment and the modification in the group of the first embodiment is in the group of the third embodiment obtained in the same time. It is superior to the statistical accuracy of the images in the embodiment and the modification. However, the statistical error caused by the amplitude of the out-of-focus image is significantly larger than the statistical error caused by the out-of-focus image in the conventional confocal interference microscope, using the apparatus described in the third embodiment and the modification. Can be reduced.

The complex amplitude of the wavenumber-filtered and spatially-filtered background beam at the detection image plane in the third group of embodiments and variants and the wavenumber-filtered and spatially-filtered reflection reference The magnitude of the mutual interference term between the complex amplitudes of the beams is substantially equal to the magnitude of the corresponding mutual interference term of the conventional confocal interference microscope when compared on a pixel-by-pixel basis. However, within a given time, the statistical error for each image point in the line image region of the target material obtained with the device in the embodiment and the modification in the third group is obtained in the same time. This is substantially equivalent to the statistical error of one image point of a conventional confocal microscope. This also applies to image processing of a two-dimensional area of the target material. This difference can be compared with the statistical error caused by the amplitude of the out-of-focus image in the conventional confocal microscope method, considering the statistical accuracy of the image of the line region or the two-dimensional region of the target material obtained at the same time. On the other hand, the third group of the embodiments and the modified examples are grounds for concluding that the statistical error resulting from the amplitude of the out-of-focus image is greatly reduced.

[0246] Preferred embodiments 13, 14, 15, 16 and their variants in the fourth group of this embodiment, except that the phase shifters 14, 24, 34, 34a are omitted. , And are composed of the same components and subsystems as those of the fifth, sixth, seventh, and eighth embodiments. The description of the fourth group of embodiments and other parts related to the modifications thereof is different from the examples in the second embodiment group except for the level of background reduction and compensation from out-of-focus images. This is the same as the description part corresponding to the example.

The level of background reduction and compensation from the out-of-focus image in the embodiment and the modification in the second embodiment group is different from the out-of-focus image in the embodiment and the modification in the fourth embodiment group. Better than background reduction and compensation levels. However, the statistical error caused by the amplitude of the out-of-focus image is compared with the statistical error caused by the amplitude of the out-of-focus image in the conventional confocal interference microscope. Significant reductions can be made with the equipment shown.

The complex amplitude of the wavenumber-filtered and spatially-filtered background beam at the detection image plane in the fourth group of embodiments and variants and the wavenumber-filtered and spatially-filtered reflection reference The magnitude of the mutual interference term between the complex amplitudes of the beams is substantially equal to the magnitude of the corresponding mutual interference term of the conventional confocal interference microscope when compared on a pixel-by-pixel basis. However, within a given time, the statistical error for each image point in the line image area of the target material obtained with the device in the embodiment and the variant in the fourth group is obtained in the same time This is substantially equivalent to the statistical error of one image point of a conventional confocal microscope. This also applies to image processing of a two-dimensional area of the target material. This difference can be compared with the statistical error caused by the amplitude of the out-of-focus image in the conventional confocal microscope method, considering the statistical accuracy of the image of the line region or the two-dimensional region of the target material obtained at the same time. In the fourth group of the embodiments and the modified examples, the grounds for concluding that the statistical error resulting from the amplitude of the out-of-focus image is greatly reduced.

Embodiments 17, 18, 19, and 20 of the preferred embodiments in the fifth group of this embodiment and their modified examples are the probe lenses that do not correct the chromatic aberration in the embodiments and modified examples of the first group. Are respectively composed of the same components and subsystems as in Examples 1, 2, 3, and 4, except that is replaced by a probe lens for correcting chromatic aberration. The description of the fifth group of embodiments and other parts related to its variants is in the group of the first embodiment, except for the level of statistical accuracy of the images obtained at a given time interval. This is the same as the description part corresponding to the embodiment and the modification.

The level of background reduction and compensation from the out-of-focus image in the embodiment and the modification in the fifth embodiment group is different from the out-of-focus image in the embodiment and the modification in the first embodiment group. Equivalent to the level of background reduction and compensation. However,
The statistical error caused by the amplitude of the out-of-focus image is compared with the statistical error caused by the amplitude of the out-of-focus image in the confocal interference microscopes of the fifth embodiment and the modified example. This can be reduced by using the devices shown in the examples and modifications. In the group of the fifth embodiment, image points are continuously collected with time.

The level of background reduction and compensation from out-of-focus images in the embodiments and modifications in the fifth embodiment group is the same as the background reduction from out-of-focus images obtained by the conventional confocal interference microscope method. And considerably higher than the level of compensation. The complex amplitude of the wavenumber-filtered and spatially-filtered background beam and the complex of the wavenumber-filtered and spatially-filtered reflected reference beam in the detected image plane in the fifth group of embodiments and variants. The magnitude of the mutual interference term between the amplitudes is significantly reduced when compared on a pixel-by-pixel basis, as compared to the corresponding mutual interference term of a conventional confocal interference microscope. Therefore, the statistical accuracy and systematic error in the embodiment and the modification in the fifth embodiment group for the image obtained in a specific time are the statistical accuracy of the image obtained by the conventional focus interference microscope method. And compared with the systematic error is much improved.

Without departing from the spirit of the invention, apodizing the phase shifters 14, 24, 34, 34a to vary the properties of the device according to the invention with respect to the extent of the reduction of the out-of-focus image and the magnitude of the spatial resolution Can be. Furthermore, without departing from the spirit of the invention, the function of the phase shifters 14, 24, 34, 34a can also be realized by components consisting of concentric small rings or other shapes, or by other combinations of phase shifters. can do.

The phase shifters 14, 24, 34, 34a, 44 may be of an electro-optical type or a dispersive optical type. The following paragraph shows an example of a dispersive optical system associated with broadband operation. Also,
The phase shift obtained by the phase shifter 44 can also be realized by a mirror such as the reference mirror 120 installed in a direction perpendicular to the reflection surface of the mirror.

If the phase shift caused by the phase shifters 14, 24, 34, 34a, 44 is independent of the wavelength, the device according to the invention has improved performance over a wide band. Phase shifter 14,2
By properly designing 4,34,34a, 44, a phase shifter that meets the needs for wideband can be obtained. This is for example the case of A. Hill, JWFigoski, PT Ballall et al., 1980.
U.S. Pat.No. 4,213,706, filed in July, `` Background Compensated Interferometer '';
It is disclosed in PTBallard et al., U.S. Pat. No. 4,304,464, filed December 1981, entitled "Background Compensated Interferometer."

The five embodiments and the modified examples include an embodiment and a modified example for writing information on a target material made of a recording medium, respectively. The embodiments and the modifications corresponding to the five embodiments and the modifications respectively comprise a method and an apparatus for writing information, but have the following structural differences in the following points. That is, the primary mirror and reference mirror subsystems are interchangeable, and the detector and detector pinhole are replaced by a write mirror that directs light from a light source incident substantially from the back. The reflectivity of the write mirror and the phase shift introduced by the write mirror will be a function of the position of the write mirror, which is positioned in correspondence with the procedure for generating the phase shift to form the desired image on the target material. By the procedure for generating the phase shift, a reference beam that is wave-number-filtered and spatially-filtered to obtain 1, 2, 3, and 4 measurement light intensities in the fifth embodiment and the modification example is obtained. Functions similar to those obtained in the procedure for introducing a series of phase shifts are realized.

In the embodiment for writing described here, the writing procedure consists of many different mechanisms, and the recording medium, which is an optical disc, also consists of many different materials and their combinations. As a recording method, there is a method utilizing an electro-optical effect or a magneto-optical effect such as a Faraday rotation, a Kerr effect, and a photochemical drilling effect.

If the magneto-optical effect is used in a recording process for reading stored information by detecting scattering or changes in the state of polarization of the illuminated probe beam,
A fifth group of embodiments is configured to detect the polarization state of the scattered probe beam in addition to the complex amplitude of the scattered probe beam. In a fifth group of embodiments,
The polarization state of the scattered probe beam can be measured by measuring the polarization state of the scattered probe beam by passing the scattered probe beam through an analyzer such as a polarizing beam splitter, or by measuring the complex amplitude of the polarization state of the scattered probe beam separated by the analyzer. Is measured.

In the case where an amplitude recording medium, a non-linear amplitude recording medium, and / or a phase recording medium are used in the embodiment described here, the data density stored in the storage area is N × M (N
And M have the same meaning as described in the reading example of the group of the fifth embodiment), and an example of reducing statistical errors and systematic errors related to images in a recording medium. Is obtained. The content of the information stored in a specific storage area,
It is controlled by the spatial distribution of the reflectivity and by the spatial distribution of the phase shift caused by the writing mirror in the writing embodiment and its variants. The selected reflectivity and phase shift produced by the write mirror are controlled by a phase shifter and an electro-optic amplitude modulator located in front of the mirror. The states of the electro-optic amplitude modulator and the phase shifter are controlled by a computer. The choice of reflectivity and phase shift is made by an electrical process similar to that used in the selection of the magnitude and phase of the measured complex scattering amplitude in the fifth group of embodiments.

In the first and third groups of embodiments and variants, the wavenumber-filtered and spatially-filtered scattering probe beam measured in the axial direction of the probe lens and the wavenumber-filtered and spatially-filtered The interference term between the reflected reference beams is proportional to the Fourier-transformed value of the complex scattering amplitude in the image region of the target material. Similarly, the information stored in the storage area by the writing method of the embodiment and the modified example corresponds to the embodiment and the modified example of the first and third groups, and the Fourier transform of the complex reflectance of each area on the writing mirror. It is proportional to the interference term between the wave number filtered and spatially filtered scattering probe beam and the wave number filtered and spatially filtered reflected reference beam proportional to the transformed value.

The interference term between the wavenumber-filtered and spatially-filtered beam reflected by the writing mirror and the wavenumber-filtered and spatially-filtered reflected reference beam is the information term stored in the storage area. When setting the complex reflectivity of the write mirror to be proportional to the inverse Fourier transform, a wavenumber-filtered and spatially-filtered scattering probe beam and a wavenumber-filtered and spatially-filtered reflection reference Obviously, the interference terms measured in the axial direction of the probe lens shown in the first and third groups of embodiments and variants between the beams are proportional to the stored original information. Therefore, in this example, the first and third
It is not necessary to perform a Fourier transform of the complex scattering amplitude measured in the axial direction of the probe lens shown in the embodiments and the modifications of the group.

One advantage of the first and third group of embodiments is that, compared to a series of measurements obtained by conventional single pinhole confocal interference microscopy or holography, the line area in the depth direction of the wafer is reduced. Substantially simultaneously, greatly reducing statistical errors and greatly reducing or at the same level the background from out-of-focus images, to produce a tomographic complex amplitude image of a wafer used in the manufacture of integrated circuits. It is a point that can be obtained. Simultaneous image processing of the line area in the depth direction of the wafer can greatly reduce the sensitivity to the position movement in the depth direction of the wafer caused by, for example, movement, scanning, and vibration of the wafer. In addition, if image processing is performed on line regions in the depth direction of the wafer at the same time, it is possible to recognize the position of the surface and / or the inner surface of the wafer based on information obtained simultaneously from different depths.

Another advantage of the first and third group of embodiments is that compared to a series of measurements obtained by conventional single pinhole, confocal interference microscopy or holography, the depth of the wafer can be reduced. By substantially simultaneously processing the dimensional domain, the statistical error is greatly reduced, and the background from out-of-focus images is greatly reduced or at the same level, the tomographic complex amplitude of the wafer used in the manufacture of integrated circuits. The point is that an image is obtained. One axis of the two-dimensional area of the wafer is parallel to the depth direction of the wafer. Simultaneous image processing of the two-dimensional region in the depth direction of the wafer can greatly reduce the sensitivity to the depth and lateral position movement of the wafer resulting from, for example, wafer movement, scanning, and vibration. Further, if the two-dimensional area of the wafer is simultaneously image-processed, it is possible to recognize the position of the surface and / or the inner surface of the wafer which can be used for the registration purpose, based on the information obtained simultaneously from the other areas. .

Yet another advantage of the first and third groups of embodiments is that compared to a series of measurements obtained with a conventional single pinhole focus interference microscope or holography,
For example, by substantially simultaneously imaging depth line regions of an in vivo sample that can be used in a non-invasive biopsy of a biochemical sample, statistical errors are greatly reduced and background from out-of-focus images is greatly increased. The point is that a tomographic complex amplitude image of the in-vivo sample can be obtained at a reduced or equivalent level. If image processing is performed simultaneously on the line regions in the depth direction of the biochemical sample, the sensitivity to the position shift in the depth direction of the biochemical sample caused by movement, scanning, vibration, or the like of the biochemical sample can be greatly reduced. Also, if image processing is performed simultaneously on the line regions in the depth direction of the biochemical sample, it is possible to recognize the position of the surface and / or the inner surface of the biochemical sample based on information obtained simultaneously from different depths. Become.

Another advantage of the first and third groups of embodiments is that the depth of the biochemical sample can be compared with a series of measurement results obtained by a conventional single pinhole type, slit type focus interference microscope or holography. By simultaneously imaging two-dimensional regions in the vertical direction, statistical errors are greatly reduced, and background from out-of-focus images is greatly reduced or at the same level, for example, in non-invasive biopsy of biochemical samples. The point is that a tomographic complex amplitude image of the in vivo sample that can be used is obtained. One axis of the two-dimensional region of the biochemical sample is parallel to the depth direction of the biochemical sample. Simultaneous image processing of two-dimensional regions in the depth direction of a biochemical sample can greatly reduce the sensitivity to biochemical sample depth and lateral position shifts caused by, for example, biochemical sample movement, scanning, and vibration. it can. In addition, if the two-dimensional area of the biochemical sample is image-processed simultaneously, the position of the surface and / or the inner surface of the biochemical sample that can be used for registration purposes can be recognized based on the information obtained simultaneously from other areas. Becomes possible.

One advantage of the second and fourth group of embodiments is that it compares with a series of measurements obtained by conventional single pinhole confocal interference microscopy or holography and can either touch the wafer surface or Image processing of the line regions substantially simultaneously, greatly reducing statistical errors and greatly reducing, or at the same level, background from out-of-focus images, with the tomographic complexities of wafers used in integrated circuit manufacturing. The point is that an amplitude image can be obtained. If image processing is performed on the line area on the wafer surface or at the same time, the sensitivity to the movement of the wafer position caused by, for example, the movement, scanning, and vibration of the wafer can be greatly reduced. Also,
By simultaneously processing the two-dimensional area of the wafer surface or in contact with the wafer surface, it is possible to recognize the position of the reference area inside the wafer that can be used for registration purposes based on information obtained simultaneously from different places Becomes

One of the further advantages of the second and fourth group of embodiments is that compared to a series of measurements obtained by conventional single pinhole confocal interference microscopy or holography, the contact with biochemical samples or By substantially simultaneously imaging line areas on the biochemical sample surface, statistical errors are greatly reduced and background from out-of-focus images is greatly reduced or at the same level, for example, non-invasive biopsy of biochemical samples. The point is that a tomographic complex amplitude image of an in-vivo sample can be obtained. Imaging a line region of a biochemical sample in contact with or substantially simultaneously with the biochemical sample can greatly reduce the sensitivity to biochemical sample position shifts resulting from, for example, biochemical sample movement, scanning, or vibration. it can. Also, if the two-dimensional area of the biochemical sample surface is in contact with the biochemical sample surface or the two-dimensional area of the biochemical sample surface is image-processed at the same time, the reference area inside the biochemical sample can be used for registration purposes based on information obtained simultaneously from different places Can be recognized.

One advantage of the fifth group of embodiments is that it significantly reduces background from out-of-focus images when compared to a series of measurements obtained by conventional single pinhole confocal interference microscopy or holography. However, the point is that a tomographic complex amplitude image of a wafer used in the manufacture of an integrated circuit and one-dimensional, two-dimensional, and three-dimensional images of the wafer are generated.

One advantage of the fifth group of embodiments is that compared to a series of measurements obtained by conventional single pinhole confocal interference microscopy or holography, the background from out-of-focus images is greatly reduced. However, for example, a tomographic complex amplitude image of an in-vivo sample that can be used in a non-invasive biopsy of a biochemical sample, and one-, two-, and three-dimensional images of the biochemical sample are generated.

The confocal interference microscope system described above is used for recognizing alignment marks on a lithography stepper or scanner used in the manufacture of computer chips or other large-scale integrated circuits, and is also useful for superposition performance of the stepper or scanner. It is particularly useful in an independent metrology system for assessing
Also, the confocal interference microscope system described above is particularly useful for inspecting masks used in steppers or scanners and for inspecting wafers at various stages of large-scale integrated circuit manufacturing. Lithography is a key technology driving the semiconductor industry.

[0270] Improvement of overlay accuracy is described in, for example, "Semiconductor Industry Roadmap", p.82 (1997).
This is one of the five most difficult issues to be solved in order to achieve a line width (design rule) of 100 nm or less. $$ / year using lithography equipment
Production of 50-100M products improves the performance of lithography equipment (maintains performance)
The economic value it brings is enormous. 1% yield improvement in lithography
This translates into an economic benefit (loss) of about $ 1 million per year for integrated circuit manufacturers and a significant increase or decrease in competitiveness for lithography equipment manufacturers.

Overlay accuracy is assessed by printing the pattern on one level of the wafer and the next level following it, and measuring the difference in position, orientation, and twist of the two patterns with an independent metrology system. You.

This independent measurement system comprises a pattern reading microscope system, such as the confocal interference microscope described above, connected to a laser gauge controlled stage for measuring the relative position of the pattern, and a wafer handling system. .

The role of the lithography apparatus is to irradiate a photoresist-coated wafer with light having a spatial pattern. In this process, it is determined which part of the wafer is irradiated with light (alignment), and the position is irradiated with light.

In order to correctly position the wafer, there are alignment marks on the wafer, and the position is measured by a dedicated sensor such as a confocal interference microscope as described above. The measurement result of the alignment mark defines where the wafer is located in the apparatus. Based on this position information and the desired pattern specification on the wafer surface, a guide for wafer positioning is given in response to irradiation with light having a spatial pattern. Based on such information, the moving stage supporting the wafer coated with the photoresist moves the wafer so that the correct position of the wafer is irradiated with light.

At the time of exposure, light is irradiated from a light source to a reticle for dispersing irradiation light so as to have a spatial pattern. The reticle is also called a mask, and is used hereinafter as a term having the same meaning. In reduction lithography, scattered light is collected by a reduction lens to form a reduction pattern of a reticle pattern. Alternatively, in the case of proximity printing, the scattered light travels only a short distance (typically a few microns) before reaching the wafer, producing a 1: 1 image with the reticle pattern. This light irradiation initiates a photochemical reaction in the resist that converts the irradiation pattern into a latent image in the resist.

[0276] The mask must be defect-free, and if there is a defect in the pattern, the function of a semiconductor circuit manufactured based on the mask will be impaired. Before the mask is transported to the semiconductor manufacturing line, the mask passes through a mask inspection machine that checks the pattern for defects. There are two types of mask inspection methods. There are known methods of matching a die with a database and matching die dies. The first method involves an automatic scanning microscope that directly compares the mask pattern with the computer data used to generate the mask. In this method, high data processing capability similar to the data processing capability required for mask drawing is required. Any discrepancy between the mask being inspected and the data set used to generate it is considered an error. The confocal interference microscope system described above is particularly suitable for automatic mask inspection because it has the advantage of reducing the background and obtaining images of the one-dimensional region and the two-dimensional region substantially simultaneously.

Generally, a lithography system, also referred to as an exposure system, includes a light illumination system and a wafer positioning system. The light irradiation system includes a light source for irradiating ultraviolet light, visible light, X-rays, electron beams, or ion beams, and a reticle or mask for applying a pattern to the irradiation beam and performing beam irradiation with a spatial pattern. ing. In addition, in the case of reduced lithography, the illumination system includes lenses that print a spatial pattern on the wafer. The beam having this pattern information exposes the resist applied on the wafer. The illumination system further includes a mask stage for supporting the mask, and a positioning system for aligning the mask stage with the position of light illuminated through the mask. The wafer positioning system includes a wafer stage that supports a wafer, and a positioning system that aligns the irradiation light with the wafer stage. There are multiple exposure steps in the manufacture of integrated circuits. General references on lithography include, for example, “Science and Technology” by JRSheats, BWSmith (Mercel Dekker, New
York, 1998). The contents are cited here for reference.

FIG. 8a shows a lithography scanner 800 using a confocal interference microscope (not shown).
This is an example. Confocal interference microscopy systems are used in the exposure system to know exactly where the alignment marks on the wafer (not shown) are. Here, the stage 822 is used for positioning and supporting the wafer in the exposure station. The scanner 800 has a frame 802, which includes other support structures and various associated components. An exposure table 804 is provided above the lens support frame 806, and a reticle or mask stage 816 for supporting a reticle or mask is provided at the upper end thereof. Part 817 schematically illustrates a positioning system that positions the mask with respect to the exposure station. The positioning system 817 includes, for example, a piezoelectric element and an electronic circuit for controlling the piezoelectric element. Although not described in the examples shown here, the structure of the lithographic apparatus may be a mask stage or other type that requires precise positioning, as described in the microlithography section of Science and Technology by JRSheats, BWSmith, above. One or more interferometer systems are used to accurately determine the position of the moving part.

A support 813 suspended below the exposure table 804 is a wafer stage.
It has 822. Stage 822 has a plane mirror 828 for reflecting a measurement beam 854 illuminated by the interferometer system 826 onto the stage. Interferometer system 826
The component 819 is a positioning system for determining the position of the stage 822 with respect to
This is shown in a schematic diagram. The positioning system 819 includes, for example, a piezoelectric element and an electronic circuit for controlling the piezoelectric element. The interferometer system mounted on the exposure table 804 is irradiated with the reflected measurement beam.

In operation, an irradiation beam 810 such as, for example, ultraviolet (UV) from an ultraviolet laser (not shown) passes through the beam shaping optics, is reflected by a mirror 814, and proceeds downward. Thereafter, the irradiation beam passes through a mask (not shown) on the mask stage 816. The beam is irradiated through a lens group 808 provided on a lens support frame 806, and a pattern of a mask (not shown) is printed on a wafer (not shown) on a wafer stage. The exposure table 804 and various components supported by the exposure table 804 are not affected by ambient vibration by a vibration damping system illustrated by a spring 820.

As is well known, lithography is one of the important manufacturing methods in manufacturing a semiconductor device. For example, U.S. Pat. No. 5,483,343 outlines this manufacturing method. These manufacturing steps are described below with reference to FIGS. 8b and 8c. FIG. 8b is a flowchart showing a series of manufacturing processes for a semiconductor chip (for example, an IC or an LSI), a liquid crystal panel, a CCD, or the like. Step 851 is a design process for designing a circuit of a semiconductor element. Step 852 is a mask manufacturing process based on the circuit pattern design. Step 853 is a process for manufacturing a wafer using a material such as silicon.

Step 854 is a wafer process called pre-processing, in which a circuit is formed on the wafer by lithography using a so-called pre-processed mask and wafer. In order to form a mask pattern on a wafer with sufficient resolution, it is necessary to position the wafer using an interferometer. The confocal interference microscope system described above inspects the wafer surface and the inner layers formed in the wafer process,
It is extremely useful for checking and monitoring the effectiveness of lithography in wafer processing. Step 855 is an assembling step, a step called post-processing, which is a step of finishing the semiconductor chips on the wafer processed in step 854. This includes assembly (dicing and bonding) and packaging (chip sealing) steps. Step 856 is an inspection step in which the semiconductor device manufactured in step 855 is checked, such as an operation check and a tolerance check. Through these processes, the semiconductor device is completed and shipped (step 857).

The details of the wafer process are shown in the flowchart of FIG. 8C. Step 861 is an oxidation process for oxidizing the wafer surface. Step 862 is a step of forming an insulating film on the wafer surface by a CVD process. Step 863 is an electrode forming process in which electrodes are formed on the wafer by vapor deposition. Step 864 is an ion implant process for implanting ions into the wafer. Step 865 is a resist process in which a resist (photosensitive material) is applied to the wafer. Step 86
Reference numeral 6 denotes an exposure process in which a circuit pattern of a mask is printed on a wafer by exposure (lithography) through the above-described exposure apparatus. Again, as described above, confocal interference microscopy systems can improve the accuracy, resolution, and maintainability of this lithographic process.

Step 867 is a step of developing the exposed wafer. Step 868 is an etching process for removing portions other than the exposed resist image. Step 869 is a resist peeling step for peeling the resist material remaining on the wafer after the etching process. By repeating these steps, a circuit pattern is formed on the wafer and copied.

An important application of the confocal interference microscopy system described herein is the inspection of masks and reticles used in the lithography process described above. For example, Figure 9
FIG. 1 is a diagram schematically showing a mask inspection system 900. Original beam 91 from light source 910
2 is generated, and the substrate 916 supported by the movable stage 918 is irradiated with this light by the confocal interference microscope 914. To determine the relative position of the stage,
The reference beam 922 is emitted from the interferometer system 920 toward the mirror 924 installed on the beam stop component 914. Further, the measurement beam 926 is emitted toward the mirror 928 attached to the stage 918. The irradiation position of the writing beam 912 on the substrate 916 also changes according to the position change measured by the interferometer system. From the interferometer system 920, a controller 930 indicating the relative position of the inspection beam 912 on the substrate 916.
, A measurement signal 932 is transmitted. An output signal 934 is transmitted from the controller 930 to a base 936 that supports and positions the stage 918.

The confocal interference microscope 914 is controlled by the controller 930, and scans the substrate area with the inspection beam based on, for example, the signal 944. As a result, the controller 930 instructs other system components to inspect the board. In mask inspection, the mask pattern is compared directly with the computer data used to generate the mask.

Theory Discrimination of Background The devices described in the preferred embodiment are all examples of either a pinhole confocal interference microscopy system or a slit confocal microscopy system. Background reduction cap of confocal microscopy systems
activity is one of its most important attributes, and is a powerful optical sectioning property of confocal microscopy.
). This is quite different in nature from conventional microscopy, which limits the depth of field. The difference is that conventional microscopes only blur out-of-focus information, whereas confocal systems actually detect at much weaker intensity and are scattered at locations axially spaced from the focal plane. Light is defocused at the detector plane and therefore cannot pass efficiently through masks located at the detector plane (edited by T. Wilson, published by The Academic Press, London, 1990;
In the literature called confocal microscopy, C.I. J. R. Shepard and C.I. J. See Koswell, "Stereoscopic images in confocal microscopy"). For example, Fizeau interferometers used in DIP have a level of sensitivity to out-of-focus images that is comparable to that of conventional microscopes.

The features of the confocal interference microscope described in the embodiments and variants in the first, second and fifth embodiments are that both the reflected reference beam and the scattered probe beam are at the in-focus image point 48 by the pupil function. Substantial changes are made. However, the out-of-focus beam does not change substantially at the in-focus image point 48. In the embodiment and the modified example described here, the influence from the out-of-focus image is reduced as compared with the conventional confocal interference microscope,
This is a feature of the present invention.

The devices in the embodiments and the modifications of the first, second, third and fourth groups further have the form of a dispersive interferometer. Optical time domain reflection (OTDR) measures the scattering of a time-dependent light signal by a background by injecting a strong short pulse of light into an object such as a fiber. In the optical frequency domain reflection method (OFDR), a target is irradiated with monochromatic light whose frequency changes in a known pattern, and the scattering of the frequency-dependent optical signal due to the background is measured. In the embodiments and variants described here, the scattering due to the wavenumber-dependent background is measured as a function of the wavenumber k. According to the definitions of OTDR and OFDR, the form of the dispersive interferometer according to the present invention can be classified into optical wave number domain reflection method (OWRD).

If the OWRD method is used, the sensitivity to the amplitude of the in-focus image in the first and third embodiments and the modified examples can be obtained substantially simultaneously for all the axial positions at the time of exposure. Same
Using the OWRD method, in the second and fourth embodiments and modifications, at the time of exposure, the horizontal position of the line region substantially orthogonal to the optical axis of the target material image processing subsystem is set to the horizontal position of the in-focus image. Sensitivity to amplitude is obtained substantially simultaneously. In the case of a standard confocal interference microscope system, in order to obtain equivalent sensitivity to the amplitude of the in-focus image, each scan must be performed in the axis or horizontal direction of the target material.

A distinguishing feature of the confocal interference microscopy systems of the first and second groups of embodiments and variants is that the information of the point array in the image can be obtained substantially simultaneously and the conventional confocal interference The influence from the out-of-focus image is suppressed as compared with the microscope. Confocal interference microscopy is known as an optical segmentation technique for acquiring one-, two-, and three-dimensional images of an object by suppressing the effects of out-of-focus images, and a pupil function [M Born, E. Wolf, `` Basics of Optics, '' Chapter 8.6.3, pp. 423-427 (Pergamo
n Press, New York), 1959] is known as a technique for improving contrast in specific applications, and OWRD used in DIP is known as a technique for reducing phase ambiguity. However, in order to reduce both systematic and statistical errors arising from the background, combining confocal interference microscopy, pupil function correction and OWRD in the same system is the first presented in the present invention. The inventor understands.

The salient features of the confocal interference microscopes in the third and fourth embodiments and variants are:
This is a point at which information of each point array in the image can be obtained substantially simultaneously, and the influence from an out-of-focus image is suppressed as compared with the conventional confocal interference microscope. The confocal interference microscope is known as a technique for suppressing the influence from an out-of-focus image, and the OWRD used in DIP is known as a technique for reducing phase ambiguity. However, the inventor understands that combining a confocal interference microscope and an OWRD in the same system for the purpose of reducing systematic errors and statistical errors caused by the background was first presented in the present invention. I have.

A distinguishing feature of the confocal interference microscopes in the fifth group of embodiments and variants is that
, Similar to the distinguishing features of the confocal interference microscope systems in the embodiment and the modification of the group 2 in that the information of each point array in the image can be obtained substantially at the same time. In comparison, the influence from the out-of-focus image is suppressed.

Thus, the combination of confocal interference microscopy and pupil function correction in the same system for the purpose of reducing both systematic errors and statistical errors caused by the background is presented for the first time in the present invention. The inventor understands that

Impulse Response Function of In-Focus Image: Axial OWDR The first embodiment shown in FIGS. 1a to 1n was chosen as a system showing the basic principle of the features described in the previous section. The basic principle can be applied to all the four embodiments of the first embodiment group disclosed in this specification, as well as all of the modifications. The pinhole 8 shown in FIG.1b and the spatial filter pinhole 18a shown in FIGS.1h, 1i, 1m are conjugate pinholes of the confocal interference system for all optical frequencies of the light beam, while FIGS. 1j, 1k , 1n can sense only one optical frequency component of the light beam as a result of the dispersive detector elements 130a and 130b shown in FIG. 1a. A signal substantially equivalent to the confocal signal adapted for each accessible axial position obtained by the prior art is obtained as a function of the light frequency for a set of four exposures.
Can be reconstructed from the recorded intensities. This is shown theoretically in the following description. This substantially means that the device according to the invention simultaneously obtains a signal equivalent to the in-focus confocal signal according to the prior art as a function of the axial position. In contrast, in a standard confocal microscope system, to obtain the confocal signal according to the prior art as a function of the axial position, an axial physical scan of the object 112 shown in FIGS. It is necessary to perform

The non-fluorescent confocal scanning microscope has two useful modes, a reflection mode and a transmission mode. [CJR Sheppard, "Scanning Optical Microscope", Advances in optical
and electron microscopy, 10, (Academic, London, 1987): CJR Sheppard,
A. Choudhury, Optica Acta, 24 (10), 1051-1073 (1977)]. In actual operation, by scanning the object in the axial direction with a reflection mode microscope,
It is easy to make an optical cut to form a three-dimensional image. [CJR S
heppard, CJ Cogswell, J. Microscopy, 159 (Pt2), pp. 179-194 (1990):
CJR Sheppard, T. Wilson, Optics Lett., 3, 115-117 (1978): CJR
Sheppard, DK Hamilton, IJ Cox, Proc. R. Soc. Lond., A 387, 171-186.
Page (1983)].

Consider a confocal microscope having three image sections as shown in FIG. Figures 1a to 1n
For the combination of the source 10, the object 112, and the subsystem shown in FIG. 5 having the detector 114 for detecting the probe beam and the scattered probe beam, the lens 1 of FIG. 5 is replaced by the lens of the subsystem 80 shown in FIG. 16, is equivalent to the combination of lenses 26 and 36 of subsystem 81 shown in FIG.1c, and lens 46 of subsystem 82 shown in FIG.1c, and lens 2 of FIG. The lens 46 of FIG. 5 is equivalent to the combination of the lens 46 of 82 and the lens 26a of the subsystem 81a shown in FIG.
This is equivalent to the combination of the lens 36a of the subsystem 81a shown in 1h and the lens 66 of the subsystem 84 shown in FIG. 1j. For the combination of the source 10 shown in FIGS. 1a to 1n, the object 112, and the subsystem including the detector 114 for detecting the reference beam and the reflected reference beam, the lens 1 of FIG. System 80 lens
16, equivalent to the combination of lenses 26 and 36 of subsystem 81 shown in FIG. 1c, and lens 56 of subsystem 83 shown in FIG. 1e, and lens 2 of FIG. 1 is equivalent to the combination of the lens 56 of FIG. 83 and the lens 26a of the subsystem 81a shown in FIG. 1i, and the lens 3 of FIG. 5 is the same as the lens 36a of the subsystem 81a shown in FIG. This is equivalent to the combination of the system 84 with the lens 66.

Here, the optical coordinates (υi, wi, ui) of the four spaces are respectively represented by image plane spaces 7A,
Either the space of the object 112 or the space of the reference mirror 120, the space of the image plane 17aA, and the image space 47A of the detector 114 of i = 1, 0, 2, and 3 are defined.

[0299]

(Equation 1)

Here, sin α _i is the numerical aperture of the i-th space, the wave number is k = 2π / λ, λ is the wavelength of radiation in vacuum, x _i , y _i , z _i Is the optical path distance in the i-th space. These optical path distances are defined as follows.

[0301]

(Equation 2)

Here, the integration is performed along the optical path of each light, and n (x _i ′, y _i ′, z _i ′)
Is the refractive index at the position (x _i ′, y _i ′, z _i ′). The image on the confocal microscope behaves as a coherent microscope (see Shepard and Chow Harry, op.cit), which can describe the image by a coherent transfer function. The coherent transfer function is a Fourier transform of the impulse response function. Thus, FIG. 7 effective steric impulse response function of the system _{h e (v 3, v 0} , v 2, v 1) can be expressed as follows.

[0303]

(Equation 3)

Here,

[0305]

(Equation 4)

[0306]

(Equation 5)

And h _i , P _i , and W _i are the impulse response function, pupil function, and wavefront aberration function for the i-th equivalent lens, respectively (Applied Optics Journal 31st, 1992).
No. (14), pp. 2541 to 2549. Goo and C.I. J.
R. See Shepard's article 10-12). j is (-1) ^1/2 . The impulse response function is the amplitude in the image b corresponding to the point light source target. Phase shifter 14,24,24a, 34,34a, and incorporates functions 44 in a suitable pupil function P _i. Phase shifters 14, 24, 24a, 34, 34a, and 44
Function of any apodization of are also incorporated into the appropriate P _i.

Assuming that the three-dimensional object is characterized by a scattering distribution t (v ₀ ) (19)
1989, Optical Journal Am. a, C. of 6 (9). J. R. Shepard and X. Q. (See Mao's paper), the scattering per unit volume is calculated by the following equation:
(See E. Wolf's reference in the first column of the Optical Magazine of 1969, pp. 153 to 156).

[0309]

(Equation 6)

[0310] n and t are generally complex numbers, and j in equation (5) indicates that in a lossless medium, the scattered wave has a phase shifted by 1/4 cycle (90 °) with respect to the direct wave. Consider that.
It is assumed that the effects of multiple scattering are negligible. In addition, it ignores unscattered radiation. This is a valid assumption for reflection mode microscopy because direct (non-scattered) radiation does not affect the image. The image amplitude can be added over the elemental slices that make up the object. This is because the principle of superposition is effective. Furthermore, integration must be performed over the incoherent light source of the amplitude distribution A (v ₁ ). For both radiation incident on the object and radiation reflected / scattered by the object, an attenuation function a (v ₀ ) must also be included that takes into account the attenuation of the radiation at the object.

[0311] The impulse response function of the lens including the dispersion detector elements 130a and 130b is given by:

[0312]

(Equation 7)

Here,

[0314]

(Equation 8)

[0315]

(Equation 9)

G3 (k, v3) is the distributed pupil function for the scatter detector elements 130a and 130b shown in FIG. 1a. Equations (7b) and (7c) that occur in relation to the correspondence with the u term in equation (7a)
The change in the sign of u in) is due to reflection occurring in the v0 space. Therefore, the amplitude of the scattered probe beam U _S in the image plane 17a of the spatial filter pinhole 18a is:

[0317]

(Equation 10)

Here, R1 and T1 are a reflection coefficient and a transmission coefficient of the beam splitter 100, respectively. By substituting Equations (6a) and (6b) into Equation (8), US (v ₂ ) is represented by the following equation.

[0319]

[Equation 11]

The amplitude US (v2) represents the complex scattering amplitude at the spatial filter pinhole 18a shown in FIG. 1h in the device according to the invention. From the properties of the impulse response function given by equation (3), he ((v3, v2, v0, v1), the complex scattering amplitude US (v3) in the image plane 47 in the detector 114 shown in FIG. The impulse response function for the combination of the lens 36a and the lens 66 shown in 1h and 1j, h3 (v3-v2), and the convolution operation of US (v2) for the detector elements 130a and 130b shown in FIG. 1a can be obtained. The optical coordinates of plane 47 are given by v3.

[0321]

(Equation 12)

Here, t2 (v2) is a transmission function of the spatial filter pinhole 18a. An equation suitable for US (v3) of a transmission mode confocal microscope is z0 = 0, that is, exp (j2kz0) = 1,
It can be obtained from equation (10).

When using the apparatus according to the present invention, by examining the observed values of the amplitude of the interference signal obtained from the scattering by the plane transverse cross section of the object, the important features of the OWDR can be obtained without extra complexity. Can be easily shown. Taking this into account, first consider the response of the confocal interference microscope to a plane transverse section of any three-dimensional scattering object. Here, the reference mirror is a horizontal plane reflector, has a point light source,
, 2, 3, and 4 have a refractive index of 1.

The axial position of the reference mirror and the transverse cross section of the scattering object are denoted by z0, R and z0, s, respectively.
Let UR be the amplitude of the reflected reference beam in the image plane at detector 114 shown in FIG. 1k. UR can be obtained by appropriately changing the variables in equation (10). The output current I from the detector 114 for a given transverse section of the object to be scattered is
It has the following form:

[0325]

(Equation 13)

By expanding this,

[0327]

[Equation 14]

F3 is the focal length of detector area 3 and m3 is the dispersive detector elements 130a and 1
Υ3 component of the spatial frequency specific to the diffraction order used for 30b, and (Φs−Φr) is
is the phase difference between US and UR at z0, s = z0, R, and χ is the phase shift caused by the phase shifter of the reference leg of the interferometer of subsystem 83 shown in FIGS. 1e and 1g. By examining equation (11b), if the scale and phase factors are constant, the term proportional to the scattering amplitude US (z0, S, υ3, w3) in equation (11b) is It can be obtained by measuring I (z0, R, z0, S, υ3, w3, χ) in the value.望 ま し い = 望 ま し い 0, χ0 + π, χ + (π / 2) and χ0 + (3π / 2)
It is. The combination of the values of the four output currents Ii corresponding to i = 1, 2, 3, and 4, respectively, is
It is obtained by the following equation.

[0329]

(Equation 15)

[0330]

(Equation 16)

The complex expression for ΔI is defined as follows.

[0332]

[Equation 17]

Alternatively, the following is obtained by substituting the expressions (13a) and (13b).

[0334]

(Equation 18)

For a scattering target object having a finite axial thickness, the corresponding signal ΔI (z0, R,
υ3, w3) is obtained by integrating ΔI (z0, R, z0, S, υ3, w3,) with respect to z0, S. Using equation (15), ΔI (z0, R, υ3, ω3) can be expressed as follows for a scattering target object having a finite axial thickness.

[0336]

[Equation 19]

The resulting signal ΔI (z0, R, υ3, w3) is measured as a function of wavenumber k by measuring ΔI (z0,, R, υ3, w3) as a function of υ3. Examination of equation (16) reveals the following. That is, given a constant scale factor, the observed quantity ΔI is the Fourier transform of the product of the scattering amplitude U _S and the reflected reference amplitude U _R. Similar information about the target object can also be obtained with a confocal interference microscope according to the prior art. According to the device according to the invention, for the target object in the array of axial positions in the z0 direction, the information represented by ΔI (z0, R, υ3, w3) does not require scanning of the target object and independently It can be determined from a set of four measurements taken in chronological order. On the other hand, in order to perform the same four independent measurements with a confocal interference microscope according to the conventional technology, the target object is scanned for each position in the axial direction of the axial position array in the z0 direction. There must be. Therefore, by using the apparatus according to the present invention, information represented by ΔI (z0, R, υ3, w3) regarding the target object can be obtained more quickly than the conventional interference confocal microscope. These features of the present invention, in part, can increase the statistical accuracy of the current measurement and reduce the effect of movement of the target object.

As shown in the section “Impulse Response Function of In-Focus Image” on the nature of the Fourier-transformed scattering amplitude, ΔI can be obtained from the measured intensity Ii according to equation (16). Equation (16) is a Fourier transform of the product of reference amplitude U _R which is reflected and scattered amplitude US. Therefore, the information on the scattering target object itself is based on the inverse Fourier transform F-1 (ΔI (z0, R, υ3, w3) of the wavenumber k.
) Is calculated. That is,

[0339]

(Equation 20)

By substituting the equation for ΔI given by equation (16) into equation (17), the following product of the scattering amplitude U _S and the reflected reference amplitude UR is obtained.

[0341]

(Equation 21)

| U _s | exp (-jΦS) is calculated from F-1 (ΔI) based on equation (18) by [F-1 (ΔI)] / 4
Preferably, it is multiplied by [| U _R | exp (jΦR)]-1, where the reflection amplitude | U _R | exp (jΦR) is determined by a set of independent measurements. In the referenced calculations, it is important to know the value of ΦR in relation to Φ _S and Φ _{S, 0 with} all effects other than the target object. The method for determining | U _R | exp [j (ΦR-ΦS, 0)] consists of three different types of measurements. The first type of measurement is a method in which the target object 112 is replaced by a flat reflective surface with known reflective properties and the corresponding complex quantity ΔI is measured. From the corresponding complex quantity ΔI obtained by the first type of measurement method, | UR || US, 0 | exp [
j (ΦR−ΦS, 0)]. Here, | US, 0 | represents all effects other than the target object on | US |. The second type of measurement is a method of measuring one of Ii in the absence of a target object. The | UR | 2 measurement value is obtained from Ii measured in a situation where the target object does not exist. A third type of measurement is a method in which the target object 112 is replaced with a flat reflective surface having known reflective properties in the absence of a reference mirror. | I, 0 | 2 is obtained from Ii obtained by replacing the target object 112 with a flat reflective surface having known reflective properties in the absence of a reference mirror. | UR || US, 0 | exp [j (ΦR-ΦS, 0)], | UR | 2, and | U
S, 0 | 2 is used when calculating | US | exp (-jΦS) from F-1 (ΔI) [| UR | exp [j (
ΦR-ΦS, 0)]]-1 contains the information needed to determine.

The accuracy of | UR | exp [j (ΦR−ΦS, 0)] determined by the above-described procedure is, in part,
It is affected by the inherent background of the device according to the invention, ie the background level of the device itself irrespective of the target object. It should be noted that the method described above can also be used to characterize the impulse response function for the target object arm of the interferometer of the device according to the invention, | US, 0 | 2.

The axial resolution of the device according to the invention can easily be evaluated if the axial resolution exceeds the value defined by the numerical aperture of the device according to the invention for a given wavelength. it can. For these conditions, make the following assumptions to evaluate axial resolution, ignoring non-essential details that will not disturb or confuse the image: To simplify. | UR || US | and (ΦS-ΦR) are assumed to have negligible fluctuations in the interval from k- to k +, and furthermore, if the spectrum of the source is in this range Λ (k, k +, k Assuming a trigonometric function in-), the integral for k 'in equation (17) is calculated as a closed form as follows.

[0345]

(Equation 22)

Here,

[0347]

(Equation 23)

[0348] From Expression (19), | US | can be expressed as follows based on the axial spatial resolution.

[0349]

(Equation 24)

Alternatively, it can be expressed as follows based on the wavelength.

[0351]

(Equation 25)

Here,

[0353]

(Equation 26)

White Light Fringe Pattern As an example of a single reflective surface scattering object, ΔI exceeds a typical white light when exceeding the axial resolution determined by the numerical aperture of the device according to the invention for a given wavelength. 3 shows a fringe pattern. Therefore, in such a situation, the relative positions of the reference reflecting surface and the target reflecting surface can be easily identified by an axial resolution equivalent to the axial resolution given by equation (22a) or (22b). it can. this is,
This can be directly realized by taking the peak of the fringe pattern to the position of the maximum amplitude, to the fringe pattern envelope of the white light beam, or to another reference position for contrast. (See reference document by L. Deck and P. de Groot, supra.) Impulse Response Function for In-Focus Images: A fifth embodiment of the second group of transverse OWDR embodiments is referred to as "background compensation". Although selected as a system exhibiting the basic features described in the title section, this basic applies to all of the second group of embodiments and variations thereof. The impulse response function of the fifth embodiment, a confocal interference microscope system using OWDR, can be easily determined from the impulse response function derived in the previous section on the first embodiment. The pupil function Pi of the first embodiment may be replaced by the corresponding pupil function of the fifth embodiment, and the pupil function Pi of the fifth embodiment replaces the dispersive elements 130a, 130b, 130c, and 130d. Contains. (See FIGS. 1aa, 2aa, 3aa, and 4aa.) Examining equation (16) reveals the following. That is, given a constant scale factor, the observed quantity ΔI is the Fourier transform of the product of the scatter amplitude U _S and the reflected reference amplitude U _R. Similar information on the target object can be obtained even with a confocal interference microscope according to the related art. According to the device according to the invention, ΔI (z0, S, z0, R, υ3, w3) for the object in the array of lateral positions in the transverse cross-sectional plane
The information represented by can be determined from a set of four measurement values that are acquired independently and in chronological order without the need to scan the target object. On the other hand, in order to perform a similar independent measurement of four points using a confocal interference microscope according to the related art, the target object must be positioned at each lateral position of the array of lateral positions on the lateral sectional plane. Must be scanned. Therefore, by using the apparatus according to the present invention, the information represented by ΔI (z0, S, z0, R, υ3, w3) regarding the target object can be obtained more quickly than the conventional interference confocal microscope. You can. With such features of the invention,
For one thing, when measuring the current, the statistical accuracy can be increased and the degree of the influence of the movement of the target object can be reduced.

[0355] The amplitude of the out-of-focus beam U _B of out of focus amplitude detector-focus image plane 47 of the image Fresnel integral C (z
) And S (z). These integrals are defined as follows:

[0356]

[Equation 27]

[Abramowitz, Stegun, Handbook of Mathematical Functons, (Nat. Bur. Of St.
andards, Appl. Math. Ser. 55), section 7.3. pages 300-302, 1964. For a point light source 8 at v1 = (0,0,0), UB can be written as:

[0358]

[Equation 28]

Here, f2 is the focal length of the area 2 shown in FIG. 5, and (x2, y2, zB) is the image plane 57.
, And (AB / f2) is the amplitude of the out-of-focus beam at the exit pupil of the lens 2.

[0360]

(Equation 29)

Ξ2 and η2 are the coordinates of the exit pupil of lens 2 (derived from the theory of diffraction described in section 8.8.1 of Born and Wolf, supra). Level 2 discrimination, m = 2,
Under the condition that there is no apodization of the phase shifter elements of phase shifters 14, 24 and 34, the result of integration from ξ2 to η2 is

[0362]

[Equation 30]

Here,

[0364]

(Equation 31)

A is the width of the phase shift element in the ξ2 and η2 directions. For example, in the υ2 direction, m = 2, the result of performing the level 1 determination under the condition that there is no apodization of the phase shifter elements of the phase shifters 14, 24, 34 is as follows.

[0366]

(Equation 32)

| UB (V2) | 2 for level 1 discrimination for each of beams B52D-1, -2, -3, and -4
An example is shown in FIG. 6 as a function of (x2d0 / λf2) when Y2 = 0 and Z2 = 50λ (f2 / d0) 2. Examination of FIG. 6 shows that the apparatus according to the present invention is an interference confocal microscope according to the prior art.
The reason why the sensitivity to background from out-of-focus images is reduced compared to
Become clear. While conventional interference confocal microscopes are sensitive to UB,
However, in the device according to the present invention, U_BFirst-order effects on derivatives of x2 and y2
Receive. This is because U in the image plane 17a_RThat the spatial properties of are antisymmetric
by. Utilizing the nature of Fresnel Internals [Abramowitx, formerly by Stegun
See the book], in the spatial filter pinhole 18a (U_RU_B ^*+ U^* _RU_B)
The integration of the wave number components is also shown here for the confocal interference microscope according to the prior art.
In both cases, it is possible to prove that they act as described in Table 1.
It is. Note that this integrated value corresponds to the corresponding detector pinhole (U_RU _B ^* + U^* _RU_B) Is sufficiently close to the integrated value.

[0368]

[Table 1]

U ^* indicates the complex conjugate of U, and the integration is such that U _R is anti-symmetric with respect to x ₂ for level 1 discrimination, and x _{2 and} y ₂ are anti-symmetric for level 2 discrimination. This is the integral of a section around a certain position.

[0370] subjected to apodization of the phase shifter elements of phase shifters 14, 24, 34, if reducing the magnitude of the derivative of the x2 and y2 of the U _B, using the apparatus according to the invention, The discrimination against the background from the out-of-focus image can be improved so as to exceed that shown in Table 1. Apodization number T2 (
ξ2, η2),

[0371]

[Equation 33]

The result of integrating the 22 and η2 for the level 2 discrimination and m = 2 is

[0373]

(Equation 34)

Here,

[0375]

(Equation 35)

[0376] Using the properties of Fresnel internals [Abramowitx, see ibid according Stegun], the integral component of the optical frequency of the spatial filter pinhole ^{_{18a (U R U B * +}} U * R U B) The discrimination of level 2 for performing the apodization given by the equation (31) of the invention disclosed herein, and the apodization depending on ξ2 of | sin (ξ2π / a) | It is possible to prove that the result as described in Table 1 is obtained for the level 2 discrimination without apodization.
This integration value is sufficiently approximate to the value obtained by integrating the corresponding for the corresponding detector pinholes ^{_{(U R U B * + U}} * R U B).

An important feature of the apparatus embodying the present invention is that it is wavenumber filtered, spatially filtered, wavenumber filtered and spatially filtered with the reflected reference beam detected at image plane 67. The effect of this is to strongly reduce the background beam interference term for each independent volume element of the source of the out-of-focus image.
Therefore, as a result of the reduction, the systematic error generated by the background from the out-of-focus image can be significantly reduced as well as the statistical error.

Further, according to the apparatus according to the present invention, the effect that the sensitivity to the background from the out-of-focus image can be reduced as compared with the interference confocal microscope according to the related art is described in the horizontal direction. It can also be evaluated from the viewpoint of cutting force. In prior art interference confocal microscopy, the degree to which the error signal due to the cross term between the reflected reference amplitude and the background from the out-of-focus image is affected by zB depends on the intensity of the out-of-focus image. This is an order of magnitude lower than the degree to which the background detected error signal is affected.

Statistical Error Consider the response of the device of the present invention to an optional flat lateral section of the stereoscopic scanned object 112. The output current I from the detector pixel for a given lateral section of the scanned object 112 is of the form:

[0380]

[Equation 36]

Here, the integration ∬ _p is performed over the area of the pixel, and χ is the phase shifter 4
4 is the phase shift introduced by FIG. The intensity differences I ₁ -I ₂ and I ₃ -I ₄ are as follows.

[0382]

(37)

Here, I _p is defined by the following equation.

[0384]

(38)

[0385] Statistical error for ^{_{∬ p (U R U S *}} + U R * U S) dx 3 dy 3 and ^{_{j∬ p (U R U S *}} -U R * U S) dx 3 dy 3 , respectively , Can be expressed as follows.

[0386]

[Equation 39]

In deriving equations (37a) and (37b), σ ² (∬ _p | U _R | ² dx ₃ dy ₃ ) =
∬ _p | U _R | ² dx ₃ dy ₃ and σ ² (∬ _p | U _B | ² dx ₃ dy ₃ ) = ∬ _p | U _B | ² dx ₃
dy ₃ , the statistical noise of the system, is determined by the Poisson distribution of the number of detected photoemission electrons, and ∬ _p | U _R | ² dx ₃ dy ₃ and ∬ _p | U _B | ² dx ₃ dy ₃ are: Both were assumed to correspond to a large number of photoemitted electrons. ∬ _p ｜ U _R ｜ ²
_{dx 3 dy 3 »∬ p | U} S | 2 dx 3 dy 3 and ^{_{∬ p | U B | 2 dx}} 3 dy 3 »∬ p | U S | 2
For the case of dx ₃ dy ₃ , U _S on the right side of equations (37a) and (37b)
Can be ignored, and in this case, the following simple expression is obtained.

[0388]

(Equation 40)

∬_p｜ U_R|^Twodx_Threedy_Three= 2∬_p｜ U_B|^Twodx_Threedy_ThreeFrom_p｜ U_R|^Twodx_Threedy _Three ≫∬_p｜ U_B|^Twodx_Threedy_ThreeObtained when moving to 移行_p(U_RU_S ^*+ U_R ^*U_S
) Dx_Threedy_ThreeAnd j∬_p(U_RU_S ^*-U_R ^*U_S) Dx_Threedy_ThreeOf the S / N ratio for
The additional gain is a factor of about (3/2). However, this latter gain
Compensates for significant increase in dynamic range of light source output and signal processing electronics
Is the value obtained as Therefore, | U_RThe best choice for | is typically
Is performed under the conditions shown in the following equation.

[0390]

[Equation 41]

When the condition expressed by the expression (39) is satisfied, the statistical error given by the expressions (38a) and (38b) is expressed as expressed by the following inequality.

[0392]

(Equation 42)

When investigating equations (37a) and (37b) or equations (38a) and (38b),
An apparatus embodying the present invention that reduces background from out-of-focus images has a lower statistical error for a given operating value U _S and U _R compared to prior art confocal interference microscopy systems. . Typically, the S / N ratio obtained when using an apparatus embodying the present invention is (3) higher than the value obtained by a confocal interference microscope without using the present invention disclosed herein. / 2) Larger by a factor of ^1/2 .

The interpretation of Expressions (37a) and (37b), Expressions (38a) and (38b), and Expressions (40a) and (40b) are as follows. With the invention disclosed herein, a set of four intensity measurements can provide a component of the complex scatter amplitude, which for each independent location of the object is the inferred complex scatter component. The statistical error for each component of the amplitude is typically set to be within (3/2) ^1/2 of the coefficient of the limited statistical error defined by the statistical distribution of the complex scattering amplitude itself. The statistical errors referred to herein can be obtained with relatively low operating power levels of the light source and relatively low dynamic range capacity in the signal processing electronics as compared to prior art confocal interference microscopes. it can. Term independent
Using (t position) means that the related set of four measured intensities is a statistically independent set.

In the first and second embodiments shown in FIGS. 1a to 1n and FIGS. 2a to 2f, the transmittance of the phase shifter 24 is reduced to reduce the scattering probe beam and the out-of-focus image beam. By simultaneously attenuating at the image plane 47, the equation (
39) can be obtained. To obtain a given signal-to-noise ratio, this attenuation procedure requires an increase in the intensity of the light source 10 as the attenuation in the phase shifter 24 increases. The third and fourth embodiments of the present invention, shown in FIGS. 3a-3l and 4a-4f, adjust the transmission / reflection of beam splitters 100, 100a, and 100b with respect to each other. Thus, the condition given by Expression (39) can be satisfied. Typically, if either of the third or fourth embodiments is used to satisfy the condition expressed by equation (39), the light source 10 or 10a will generally be It can operate at lower power levels than required by the above described attenuation procedure based on transmission reduction.

The S / N ratio can be adjusted, for example, as a function of the optical frequency component of the light source so that it is linearly independent of wavelength. Such characteristics have already been described in the section describing the first embodiment in detail. Therefore, as already mentioned, before entering the target object 112, the wavenumber-filtered and spatially-filtered scattered probe beam P42D, normalized to the corresponding optical frequency component of the amplitude of the probe beam P22D. Amplitude generally varies with wavelength due to the effects of the factors presented. Also, the ratio of the amplitude of the wavenumber filtered and spatially filtered scattering probe beam P42D to the amplitude of the wavenumber filtered and spatially filtered background beam B62D is into the target object 112 at image point 28. Generally decreases as the depth increases. The effect of such factors on the S / N ratio can be partially compensated for by installing a wavelength filter in the reference mirror subsystem 83 or the probe beam subsystem 82. Preferably, a wavelength filter is installed in the reference mirror subsystem 83, and the scattered probe beam P42D, which is wave number filtered and spatially filtered, and the wave number transmitted through the pinhole of each detector for different wavelengths. It is desirable to adjust the wavelength filter to transmit light according to the wavelength such that the ratio of the filtered and spatially filtered reflected reference beam R42D satisfies the condition shown by equation (39).

Systematic error due to out-of-focus image | U_RAs long as | is measured, ΔI₁, ΔI_TwoAnd | U_R| Exp [j (Φ_R−Φ _{S, 0} )] Using equations (35a) and (35b) in conjunction with the measured values of _S Of the real part and the imaginary part can be obtained. Amount | U_R| Exp [j (Φ_R−Φ_{S, 0} )] Was described in the section entitled, for example, "Properties of Fourier-transformed scattering amplitudes."
Can be determined by the method. The following potential systematic error terms remain.

[0398]

[Equation 43]

[0399] These systematic error terms, | U _B | »| is conspicuous in the case of | U _S. Therefore, it is desirable to compensate for the interference terms represented by equations (41a) and (41b) to an acceptable level.

[0400] in the present invention disclosed herein, the term ^{_{∬ p (U R U B *}} + U R * U B) dx 3 dy 3 and claim ^{_{∬ p (U R U B *}} -U R * U B ) Compensation for dx ₃ dy ₃ is done in a computerized way and is simpler than required by prior art confocal interference microscopy. This is because the spatial characteristics of U _B are determined by the scattering characteristics of the three-dimensional object 112 under inspection and, therefore, by the integral expression of U _S. These integral equations (35a) and (35a)
35b) is a Fredholm-type integral equation of the second kind. Claim ∬ _p in a device embodying such a present invention ^{_{(U R U B * + U}} R * U B) dx 3 dy 3 and claim ^{_{∬ p (U R U B *}} -U R * U B) d
As x ₃ dy ₃ is reduced, computer processing is required to invert each integral equation to reduce U _S. In general, reduction rate in the required computational, Section ^{_{∬ p (U R U B *}} + U R * U B) dx 3 dy 3 and claim ^{_{∬ p (U R U B *}} -U R * U B) It is faster than the reduction rate of dx ₃ dy ₃ .

For these measurements by the interferometer, the mutual interference term or ∬_p(U_SU_B ^*+ U_S ^*U _B ) Dx_Threedy_ThreeIs compensated in contrast to the term in the device embodying the invention.
Not. The integral equations corresponding to Equations (35a) and (35b) are:
It is an expression. These integral equations are given by U_SIs a second-order integral equation. Non-linear
In order to obtain their solutions, the type integral equations require computer hardware and software.
Software is generally much more sophisticated than linear integral equations
Need that. Thus, an apparatus embodying the present invention is described in item_p(U_SU_B ^*+ U _S ^* U_B) Dx_Threedy_ThreeFrom the aspect that operates in_p(U_RU_B ^*+ U_R ^*U_B) Dx_Threedy_Three And item ∬_p(U_RU_B ^*-U_R ^*U_B) Dx_Threedy_ThreeBy converting to a mode that operates with
Provide important features of the present invention with respect to prior art pinhole confocal microscopy.
You.

Furthermore, the reduction of systematic errors caused by the background signal ∬ _p | U _B | ² dx ₃ dy ₃ is complete with the device embodying the present invention, which is the same as the prior art pinhole confocal. Note that this is in contrast to what can be obtained with a microscope.

Broadband Operation One of the important features of the present invention is that the source 10 can be extended when it is necessary to simultaneously acquire images at a plurality of image positions in the axial direction of the probe lens 46. In addition, the effect of background from out-of-focus images is greatly reduced. In discussing this feature in this disclosure, for simplicity of discussion, the aberration function is Wi = 1, and no apodization of the pupil function Pi is performed, i.e., the phase shifters 14, 24, 34, 34a, Assume no apodization of 44 is performed. For example, if apodization is applied to improve the resolution, the resulting US (v3) equation will be more complex, but for example, the spatial properties of symmetric or antisymmetric Will be easily understood by those skilled in the art.

In the case where the assumption for simplification described in the above description is made, when Expression (9) is integrated with respect to the discrimination of level 1, the following is obtained.

[0405]

[Equation 44]

Here, z0 is replaced by zS, and a ′ and d0 are respectively the phase shifter 14,
The elements 24, 34, 34a and the width of sinc≡ (sinx) / x and the distance from center to center are shown. Here, the influence of wi is suppressed. This is because in the level 1 discrimination, wi has nothing to do with background reduction due to out-of-focus images,
空間 The spatial nature of the two-way US (v2) is tuned so that the wavenumber-filtered and spatially-filtered background beam, which limits the expansion of the range of use, is greatly reduced. Because there is.

The equation for the corresponding reflected reference beam UR (v2) is as follows:

[0408]

[Equation 45]

Here, z0 is replaced by zR. Next, consider the special case of a '= d0. For this special condition, the expression (
42) and Equation (43) are as follows, respectively.

[0410]

[Equation 46]

When the equation (45) is integrated with respect to υ0, the following result is obtained.

[0412]

[Equation 47]

As an example, a two-element phase shifter system when y2 = 0, z2 = 0, υ1 = 2
FIG. 7 shows UR (v2) for (m = 1) as a function of (x2kd0 / f). The inverse symmetric spatial distribution of UR (v2) around υ is due to sin [(1/2) (υ2-υ1)]
This is clearly shown in equation (46). The spatial distribution of US (v2) generally shows similar behavior.
Equation (44) has the same mathematical structure as equation (45). By utilizing the spatial distribution of the inverse symmetry, the amplitude of the background from the out-of-focus image can be reduced at the peripheral portion. From the characteristics of the system shown by equation (46), US (v2) given by equation (44) should maintain high sensitivity to in-focus images, as long as phase (υ2-υ1) satisfies the following condition: Obviously you can do that.

[0414]

[Equation 48]

Here, [σ (q)] 2 is the variance of the independent variable q. The contribution to the signal for a given value of (υ ₂ -υ ₁ ) is (x ₂ -x ₁ ) / f
And k have a hyperbolic correlation, and (υ ₂ -υ ₁ ) is proportional to k (x ₂ -x ₁ ) / f. Thus, k and the corresponding allowed values of (x ₂ −x ₁ ) / f can satisfy equation (47), and k is limited so that an image is obtained at the detector, which results in S The / N ratio is improved (with respect to the strength of the focus signal relative to the strength of the out-of-focus signal).
From Equation (47), the following relationship is obtained.

[0416]

[Equation 49]

If one selects each of the two terms on the left side of equation (48) to operate in a mode that contributes equally to the left side,

[0418]

[Equation 50]

And

[0420]

(Equation 51)

Is obtained. From equation (50), the following equation is obtained for (σ _k / k).

[0422]

(Equation 52)

Here, rπ represents a subset of the value of (υ ₂ −υ ₁ ) that gives the peak of the factor represented by the following equation.

[0424]

(Equation 53)

As a result,

[0426]

(Equation 54)

The following is obtained. Devices embodying the present invention are effective for relatively broadband operation at λ.
Is clear from equation (53). For example, if m = 1 and r = 1,
(Σ_k/ K)<0.35, and if m = 2 and r = 1, then (σ_k/ K) < 0.18.

The range of values of r that can be used effectively is limited. This limitation is due to taking into account the S / N ratio. At each peak of the coefficient given by equation (52) that contributes to the observed signal, the signal strength is improved. However, as the number of included peaks increases, and thus the maximum value of r, ie, r _max , the bandwidth for k must be reduced according to equation (53).

When using level 2 identification in any of the second, fourth or sixth embodiments of the present invention, the spacing between light source pinholes is also limited. This limitation can be obtained using a similar type of analysis as the analysis of the broadband operating section. It is clear from the system characteristics as shown in FIG. 14 that as long as the following equation (46) holds, high sensitivity is maintained with respect to U _S (v ₂ ) for the focused image.

[0430]

[Equation 55]

Here, δv ₁ is the distance between each adjacent pinhole of the linear light source pinhole array. Right limit expressed by equation (49) and (50), it is clear that does not depend on x ₁ or y _1. Thus, apparatus embodying the present invention, subjected to the action of the point light sources, the range of values for x ₁ and y ₁ are not inherently exerted limit.

Observation through turbid media Another salient feature of the invention disclosed herein is that it significantly reduces the effect of background from out-of-focus images when observed through turbid media. It is. The impulse response function h _{A, M} for performing observation through a turbid medium is as follows.

[0433]

[Equation 56]

Here, h _A is an impulse response function of the apparatus when observation is performed through a non-turbulent medium, h _M is an impulse response function for a turbulent medium, and * is h _A and h _M Means convolution operation. h _A * h _M Fourier transform F (h _A * h _M) of can be expressed by the following equation.

[0435]

[Equation 57]

The impulse response function h _M is very well represented by a Gaussian distribution given by:

[0437]

[Equation 58]

Here, σ ² is the variance of h _M. h _M Fourier transform F of (h _M) is given by the following equation.

[0439]

[Equation 59]

Here, q is a spatial angular frequency vector (angular sp
atomic frequency vector). The lowest frequency peak of h _A is at the frequency indicated by the following equation.

[0441]

[Equation 60]

It is clear from equations (56) and (58) that when q = (d ₀ / λ) holds, a relatively large value for h _{A, M} is maintained when the following equation holds.

[0443]

[Equation 61]

[0444] Or

[0445]

(Equation 62)

When using equations (59) and (61), the value of d _{0 that} can be used is limited by the following conditions.

[0447]

[Equation 63]

Thus, a tomographic radiation imaging system embodying the present invention can be configured to maintain relatively high sensitivity to spatial frequencies below the ablation frequency provided by h _M.

According to the present invention, for a reference beam amplitude of arbitrary spatial characteristics, an interference term between the amplitude of the background light (ie, the out-of-focus returning probe beam) and the amplitude of the reference beam may be undesirably systematic. It is important in controlling the occurrence of errors and in generating unwanted statistical errors. In the above embodiment of the present invention, the interference term between the amplitude of the background light and the amplitude of the reference beam is reduced because the phase shift causes the reference beam to have an antisymmetric spatial characteristic.
Because this interference term is reduced, the data generated by the single pixel detector does not introduce unacceptably large systematic or statistical errors.

Also, the amplitude of the wave number filtered and spatially filtered reflected reference beam and the wave number filtered and spatially filtered reflected reference beam and the wave number filtered and spatially filtered scattering It will be appreciated that there is a relationship between the probe beam (ie, the required signal) and the cross term. The reference beam is the amplitude of the wavenumber filtered and spatially filtered reflected reference beam.
Detected as a square. The wavenumber-filtered and spatially-filtered scattering probe beam is the cross-term of the wavenumber-filtered and spatially-filtered reflected reference beam and the wavenumber-filtered and spatially-filtered scattered probe beam, That is, it is detected as the value obtained by multiplying the amplitude of the wave number-filtered and spatially filtered scattering probe beam by the amplitude of the wave number-filtered and spatially filtered reflected reference beam. Thus, there is a correlation between the detected wavenumber-filtered and spatially-filtered reflected reference beam and the wavenumber-filtered and spatially-filtered scattered probe beam. This is because the amplitudes of the wavenumber-filtered and spatially-filtered reflected reference beams are each included. Due to this relationship, statistical accuracy can be increased if the properties of the target object are determined using such cross terms.
As a result, based on data obtained by a multi-pixel detector that detects the cross term of a wavenumber-filtered and spatially-filtered reflected reference beam and a wavenumber-filtered and spatially-filtered scattered probe beam. Thus, accurate characterization of the target object can be performed. The reason is that the statistical accuracy obtained for a given pixel of a multi-pixel detector is based on the number of photoelectrons generated in the pixel in response to a wavenumber-filtered and spatially-filtered scattered probe beam. But not corresponding to the square of the amplitude of the wavenumber-filtered and spatially-filtered reflected reference beam or the square of the amplitude of the wavenumber-filtered and spatially-filtered background beam. Because there is no.

Further, those skilled in the art will appreciate that additional and / or additional optics and detectors can be incorporated into one of the disclosed embodiments of the present invention. For example, in a variation, a polarizing beam splitter can be used, or used with additional phase shifting elements, to change the properties of the radiation used to probe the material of interest.
Another example adds a detector to monitor the intensity of the light source. These and other obvious changes can be introduced without departing from the spirit and scope of the invention.

It should be understood that the phase shifter 34 can be omitted for the examples of FIGS. 1a through 1n. In this case, the image of the point light source 8 generated at the image point 38 of the focused image plane 37 is the image of the point light source 8 at which the reflected reference beam is generated at the image point 48 of the focused image plane 47. It differs from the image described above, though it does not substantially replace the image described above. Similarly, FIGS. 2a to 2f
In the drawings, the phase shifter 34 can be omitted, and FIGS. 3a to 31 and 4a to 4
The phase shifters 34 and 34a can be omitted in FIG.

Further, as long as the spatial distribution of the amplitude of the reflected reference beam at the single-pixel detector plane results in a spatially substantially anti-symmetric distribution, the phase shifters 14, 24, 24a, 34
, And 34a, it should be understood that the spatial features of the phase shifting elements can be different from and / or apodized to the features described above. However, the image data generated by the single-pixel detector must be processed in a slightly different manner from the above-described embodiments of the present invention to generate the desired tomographic image of the target material 112.

It will be appreciated by those skilled in the art that the interferometer and variations thereof described herein as embodiments may be configured as a confocal interference microscope operating in transmission mode without departing from the scope and spirit of the invention. Will be easy to understand. The transmission mode is
This would be a desirable mode when using the device according to the invention in certain read and write modes, such as detecting changes in the polarization state of the probe beam.

Further, the interferometers of the above-described embodiments can be used, for example, to probe the material of interest 112 with polarized light, or through the interferometer to a single or multi-pixel detector. It should be understood that the polarization type may be used to increase the power. However, additional optical elements, such as polarizing beam splitters, need to be added to the above-described apparatus for the purpose of mixing the reflected reference beam and the scattered probe beam at a single pixel detector or a multi-pixel detector.

[Brief description of the drawings]

1a to 1n, which are associated together, show in schematic form a presently preferred first embodiment of the invention. In a first group of embodiments, FIG. 1a shows the optical path between subsystems 80 and 81, 81 and 82, 81 and 83, 83 and 81a, 81a and 84, from computer 118 to translator 116 and subsystem 83. The path of the electrical signal to the phase shifter 44 and the path of the electrical signal from the detector 114 of the subsystem 84 to the computer 118 are shown. FIG. 1b shows the subsystem 80, the plane of FIG. 1b being orthogonal to the plane of FIG. 1a. FIG. 1c shows the subsystem 81, the plane of FIG. 1c being orthogonal to the plane of FIG. 1a. FIG. 1 d shows the subsystem 82 when the probe beam enters the subsystem 82.
And the plane of FIG. 1d is orthogonal to the plane of FIG. 1a. FIG. 1e shows the subsystem 83 when the reference beam enters the subsystem 83, the plane of FIG. 1e being orthogonal to the plane of FIG. 1a. FIG. 1f shows subsystem 8 when the probe beam exits from subsystem 82.
2 and the plane of FIG. 1f is orthogonal to the plane of FIG. 1a. FIG. 1g shows the subsystem 83 when the reference beam exits from the subsystem 83, the plane of FIG. 1g being orthogonal to the plane of FIG. 1a. FIG. 1h shows the subsystem 8 when the probe beam enters the subsystem 81a.
1a, wherein the plane of FIG. 1h is orthogonal to the plane of FIG. 1a. FIG. 1i shows the subsystem 81a when the reference beam enters the subsystem 81a.
And the plane of FIG. 1i is orthogonal to the plane of FIG. 1a. FIG. 1j shows the subsystem 84 when the probe beam enters the subsystem 84.
And the plane of FIG. 1j is orthogonal to the plane of FIG. 1a. FIG. 1k shows the subsystem 84 when the reference beam enters the subsystem 84, the plane of FIG. 1k being orthogonal to the plane of FIG. 1a. FIG. 11 shows subsystem 82 where the out-of-focus beam of subsystem 82 results from scattering and / or reflection of light at subsystem 82, the plane of FIG. 11 being orthogonal to the plane of FIG. 1a. FIG. 1m shows subsystem 81a where the out-of-focus beam of subsystem 81a results from light scattering and / or reflection at subsystem 82, the plane of FIG. 1m being orthogonal to the plane of FIG. 1a. FIG. 1n shows the subsystem 84 when the background light beam enters the subsystem 84, the plane of FIG. 1n being orthogonal to the plane of FIG. 1a. FIGS. 1aa to 1ai, associated together, relate to certain ones of FIGS. 1a to 1n and show in schematic form a fifth currently preferred embodiment of the invention. Second
In a group embodiment, FIG. 1aa shows beam splitter 100 and subsystem 82aa, beam splitter 100 and subsystem 83aa, subsystems 82aa and 85, optical paths between subsystems 83aa and 95, translator 116 and subsystem 83aa. Of the electric signals 132 and 133 to the phase shifter 44 of FIG. FIG. 1ab shows the subsystem 82aa when the probe beam enters the subsystem 82aa, and the plane of FIG. 1ab is orthogonal to the plane of FIG. 1aa. FIG. 1ac shows the subsystem 8 when the probe beam enters the subsystem 85.
5 and the plane of FIG. 1ac is orthogonal to the plane of FIG. 1aa. FIG. 1ad illustrates the subsystem 8 when the reference beam enters the subsystem 83aa.
3aa, the plane of FIG. 1ad being orthogonal to the plane of FIG. 1aa. FIG. 1ae shows the subsystem 95 when the reference beam enters the subsystem 95, the plane of FIG. 1ae being orthogonal to the plane of FIG. 1aa. FIG. 1af shows the subsystem 85 when the probe beam exits from the subsystem 85, the plane of FIG. 1af being orthogonal to the plane of FIG. 1aa. FIG. 1ag shows the subsystem 82aa when the scattered probe beam exits from the subsystem 82aa, the plane of FIG. 1ag being orthogonal to the plane of FIG. 1aa. FIG. 1ah shows the subsystem 95 when the reflected reference beam exits from the subsystem 95, the plane of FIG. 1ah being orthogonal to the plane of FIG. 1aa. FIG. 1ai shows subsystem 83aa when the reflected reference beam exits from subsystem 83aa, with the plane of FIG. 1ai orthogonal to the plane of FIG. 1aa.

FIGS. 2a to 2f, which are associated together, show in a schematic form a second currently preferred embodiment of the invention. FIG. 2a shows an optical path between subsystems 80a and 81, 81 and 82, 81 and 83, 82 and 81b, 83 and 81b, 81b and 84a, a translator 116 from computer 118 and a phase shifter 44 of subsystem 83. Signal path to the detector and detector 1 of subsystem 84a
The path of the electrical signal from 14a to the computer 118 is shown. FIG. 2b shows the subsystem 80a, the plane of FIG. 2b being orthogonal to the plane of FIG. 2a, the direction of the linear source and the linear array of pinholes 8a being in the plane of FIG. 2a. FIG. 2c illustrates subsystem 8 when the probe beam enters subsystem 81b.
1b, the plane of FIG. 2c is orthogonal to the plane of FIG. 2a, and the linear array of pinholes 18b is in the plane of FIG. 2a. FIG. 2d shows the subsystem 81b when the reference beam enters the subsystem 81b.
2d is orthogonal to the plane of FIG. 2a, and the linear array of pinholes 18b is in the plane of FIG. 2a. FIG. 2e shows subsystem 8 when the probe beam enters subsystem 84a.
4a, wherein the plane of FIG. 2e is orthogonal to the plane of FIG. 2a. FIG. 2f shows the subsystem 84a when the reference beam enters the subsystem 84a.
And the plane of FIG. 2f is orthogonal to the plane of FIG. 2a. FIG. 2aa, in connection with certain of FIGS. 2a to 2f, shows in a schematic form a sixth currently preferred embodiment of the invention. FIG. 2 in the embodiment of the second group.
aa is the beam splitter 100 and subsystem 82aa, beam splitter 100 and subsystem 83aa, subsystems 82aa and 85, the optical path between subsystems 83aa and 95, translator 116 and subsystem 83
The paths of electrical signals 132 and 133 to aa phase shifter 44 are shown, respectively.

FIGS. 3a to 3l, which are associated together, show in a schematic form a third currently preferred embodiment of the invention. FIG. 3a shows subsystems 80 and 81, 80 and 81c, 81 and 82, 81c and 83a, 82 and 81a, 83a and 81a.
, 81a and 84, the path of the electrical signal from the computer 118 to the translator 116 and the phase shifter 44 of the subsystem 83a, and the path of the electrical signal from the detector 114 of the subsystem 84 to the computer 118. Is shown. FIG. 3b shows the subsystem 80, the plane of FIG. 3b being orthogonal to the plane of FIG. 3a. FIG. 3c shows the subsystem 81, the plane of FIG. 3c being orthogonal to the plane of FIG. 3a. FIG. 3d illustrates the subsystem 82 when the probe beam enters the subsystem 82.
And the plane of FIG. 3d is orthogonal to the plane of FIG. 3a. FIG. 3e shows subsystem 81c, the plane of FIG. 3e being parallel to the plane of FIG. 3a. FIG. 3f shows the subsystem 83a when the reference beam enters the subsystem 83a.
3f, the plane of FIG. 3f is parallel to the plane of FIG. 3a and the phase shifters 34 and 3
4a is shown rotated 90 degrees about axes 3a and 3c for illustrative purposes only. FIG. 3g illustrates subsystem 8 when the probe beam exits from subsystem 82.
2 and the plane of FIG. 3g is orthogonal to the plane of FIG. 3a. FIG. 3h shows the subsystem 83 when the reference beam exits from the subsystem 83a.
3h, the plane of FIG. 3h is orthogonal to the plane of FIG. 3a and the phase shifters 34 and 34
a is shown rotated 90 degrees about axes 3a and 3c for illustration only. FIG. 3i shows subsystem 8 when the probe beam enters subsystem 81a.
1a, the plane of FIG. 3i being orthogonal to the plane of FIG. 3a. FIG. 3j shows the subsystem 81a when the reference beam enters the subsystem 81a.
And the plane of FIG. 3j is orthogonal to the plane of FIG. 3a. FIG. 3k shows the subsystem 84 when the probe beam enters the subsystem 84.
And the plane of FIG. 3k is orthogonal to the plane of FIG. 3a. FIG. 31 shows the subsystem 84 when the reference beam enters the subsystem 84, the plane of FIG. 31 being orthogonal to the plane of FIG. 3a. FIGS. 3aa and 3ab, in connection with certain ones of FIGS. 3a to 31, show in a schematic form a currently preferred seventh embodiment of the invention. In the second group of embodiments, FIG. 3aa illustrates the beam splitter 100 and subsystem 82aa, the beam splitter 100 and subsystem 83ab, the subsystems 82aa and 8aa.
5, the optical path between subsystems 83ab and 95, the path of electrical signals 132 and 133 to translator 116 and phase shifter 44 of subsystem 83ab, respectively. FIG. 3ab shows subsystem 83ab when the reflected reference beam exits from subsystem 83ab, the plane of FIG. 3ab being parallel to the plane of FIG. 3aa, and phase shifters 34 and 34a are only shown It is shown rotated 90 degrees about axes 3b and 3f.

FIGS. 4a to 4f, which are associated together, show in schematic form a fourth currently preferred embodiment of the invention. FIG. 4a shows subsystems 80a and 81, 80a
And 81c, 81 and 82, 81c and 83a, 82 and 81b, 83a and 8
1b, 81b and 84a, the optical path between the computer 118 and the translator 11
6 illustrates the path of the electrical signal to the phase shifter 44 of the subsystem 83a and the path of the electrical signal from the detector 114a of the subsystem 84a to the computer 118. FIG. 4b shows subsystem 80a, the plane of FIG. 4b being orthogonal to the plane of FIG. 4a. FIG. 4c shows subsystem 81b when the scattered probe beam enters subsystem 81b, the plane of FIG. 4c being orthogonal to the plane of FIG. 4a. FIG. 4d shows subsystem 8 when subsystem 81b receives a reflected reference beam.
1b, the plane of FIG. 4d being orthogonal to the plane of FIG. 4a. FIG. 4e shows subsystem 84a when the scattered probe beam enters subsystem 84a, the plane of FIG. 4e being orthogonal to the plane of FIG. 4a. FIG. 4f illustrates subsystem 8 when subsystem 84a receives a reflected reference beam.
4a, wherein the plane of FIG. 4f is orthogonal to the plane of FIG. 4a. FIG. 4aa, in connection with certain ones of FIGS. 4a to 4f, shows in a schematic form a currently preferred eighth embodiment of the invention. FIG. 4 in the embodiment of the second group.
aa is the beam splitter 100 and subsystem 82aa, beam splitter 100 and subsystem 83ab, subsystem 82aa and 85, the optical path between subsystems 83ab and 95, translator 116 and subsystem 83
The paths of the electrical signals 132 and 133 to the ab phase shifter 44 are shown, respectively.

FIG. 5 shows the geometry of a reflection confocal microscope with four imaging sections.

FIG. 6 shows four preferred embodiments and variants of the preferred embodiment of the present invention.
5 is a graph illustrating the amplitude of a spatially filtered out-of-focus image of a pinhole plane.

FIG. 7 shows four preferred embodiments and variants of the preferred embodiment of the present invention.
5 is a graph illustrating the spatially filtered pinhole surface reflected reference beam amplitude.

8a to 8c relate to applications in lithography and in the manufacture of integrated circuits. Here, FIG. 8a is a schematic diagram of a lithographic exposure system utilizing this confocal microscope system. 8b and 8c are flowcharts illustrating a procedure in manufacturing an integrated circuit.

FIG. 9 is a schematic diagram of a mask inspection system using the confocal microscope system.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G01N 21/27 G01N 21/27 E G02B 21/00 G02B 21/00 G03F 9/00 G03F 9/00 H G11B 7/0065 G11B 7/0065 H01L 21/027 H01L 21/30 525R (81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), EA (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM), CA, CN, JP, KR, MX, SG The beam from the out-of-focus image point (P62C) and the refocusing probe beam (P42C) interfere. The amplitude of the spatially filtered focused return probe beam (P42C) is detected as an interference term between the spatially filtered focused return probe beam (P42C) and the reference beam (R42C) in the detector plane. Detector system (114). This substantially reduces the amplitude of the interference term between the amplitudes of the out-of-focus image beam (P62C) and the reference beam (R42C), spatially filtered in the detector plane, representing the image information of interest. This reduces errors in the data generated by the detector system (114).

Claims (44)

[Claims] 1. A method for identifying a focused image of an area within and / or on an object from an out-of-focus image to reduce errors in image information of the object, comprising: Generating a probe beam and a reference beam; (b) generating an antisymmetric spatial characteristic in the reference beam; and (c) directing the probe beam to a focused image point within or on the region. Generating a focusing return probe beam by: (d) generating an antisymmetric spatial characteristic to the focusing return probe beam; and (e) replacing the reference beam of step (b) with a beam from an out-of-focus image point. Interfering; (f) interfering the reference beam of step (b) with the refocusing probe beam of step (d); and (g) by means of a detector system, the reference beam of step (b). Arm and the step (d)
Detecting the amplitude of the focused return probe beam as an interference term between the focused return probe beams, and determining the interference term between the amplitude of the out-of-focus image beam and the amplitude of the reference beam in step (b). Reducing the error in the data generated by the system to substantially reduce it to represent image information. 2. The method according to claim 1, wherein the point light source is a point on a monochromatic line light source. 3. The method of claim 1, wherein the object is a semiconductor wafer. 4. The method of claim 1, wherein said subject is a living organism. 5. The method according to claim 1, wherein the object is an optical disc, and the area is an information-carrying area in and / or on the optical disc. 6. A method for identifying a focused image of a region within and / or on an object from an out-of-focus image so as to reduce errors in image information of the object, comprising: Generating a probe beam and a reference beam; (b) generating an antisymmetric spatial characteristic in the reference beam; and (c) a beam focused on the probe beam to a line in and / or on the object. Passing the probe beam through a first dispersive element to convert the probe beam to: (d) generating a focus-return probe beam; and (e) producing an anti-symmetric spatial characteristic in the focus-return probe beam. (F) spatially filtering the focused return probe beam of step (e); and (g) detecting the spatially filtered focused return probe beam. Passing the refocused probe beam through a second dispersive element to convert it into a beam focused to a line in the plane of the vessel; and (h) spatially filtering the reference beam in step (b). (I) passing the reference beam through the second dispersive element to convert the spatially filtered reference beam into a beam focused on a line in the detector plane; and (j) out of focus. (K) spatially filtering the beam from the image point; and (k) the out-of-focus image to convert the spatially filtered beam from the out-of-focus image point to a beam focused on a line in the detector plane. Passing a beam from a point through the second dispersive element; (l) applying the spatially filtered and focused reference beam of step (i) to the out-of-focus image (K) interfering with the spatially filtered and focused beam of step (k); and (m) transforming the spatially filtered and focused reference beam of step (i) into the space of step (g). Interfering with the filtered and focused return probe beam; and (n) by means of a detector system the spatially filtered and focused reference beam of step (i) and the spatial filter of step (g). Detecting interference terms between the processed and focused refocused probe beams, the spatially filtered and focused beam amplitudes of step (k) and the spatially filtered and focused of step (i). The amplitude of the interference term between the amplitude of the reference beam and the error in the data generated by the detector system is reduced substantially to represent image information. , Including. 7. The method of claim 6, wherein the point light source is a point of a broadband line light source. 8. The method of claim 6, wherein step (c) comprises passing the probe beam through at least one diffraction grating, wherein the lines are substantially parallel to a surface of the object. Method. 9. The method of claim 6, wherein the line is substantially perpendicular to a surface of the object. 10. The method according to claim 6, comprising performing a Fourier transform on the data generated by the detector system. 11. The method according to claim 6, wherein the object is a semiconductor wafer. 12. The method according to claim 6, wherein the subject is a living body. 13. The method according to claim 6, wherein the object is an optical disk and the area is an information-carrying area within and / or on the optical disk. 14. A method for identifying a focused image of an area within and / or on an object from an out-of-focus image so as to reduce errors in image information of the object, comprising: Generating a probe beam and a reference beam; (b) generating an antisymmetric spatial characteristic in the reference beam; and (c) a beam focused on the probe beam to a line in and / or on the object. (D) generating a focus-return probe beam; (e) generating an antisymmetric spatial characteristic in the focus-return probe beam; and (f) focus return in step (e). Spatially filtering a probe beam; and (g) converting the spatially filtered defocused probe beam to a beam focused on a line in the detector plane of a detector system. (H) spatially filtering the reference beam of step (b); and (i) detecting the spatially filtered reference beam by a detector. Passing the reference beam through the dispersive element to convert it to a beam focused on a line in a plane; (j) spatially filtering the beam from an out-of-focus image point; (L) passing the beam from the out-of-focus image point through the dispersive element to convert the processed beam from the out-of-focus image point into a beam focused on a line of a detector system; the spatially filtered and focused reference beam of i) from the out of focus image point before the spatially filtered and focused step of step (k) (M) interfering the spatially filtered and focused reference beam of step (i) with the spatially filtered and focused focusing return probe beam of step (g). And (n) between the spatially filtered and focused reference beam of step (i) and the spatially filtered and focused return probe beam of step (g) by means of a detector system. Detecting an interference term, wherein the amplitude of the interference term between the amplitude of the spatially filtered and focused beam of step (k) and the amplitude of the spatially filtered and focused reference beam of step (i) is Reducing the error in the data generated by said detector system to substantially reduce it to represent image information. 15. The method of claim 14, wherein the point light source is a point of a broadband line light source. 16. The method of claim 14, wherein said object is a semiconductor wafer. 17. The method according to claim 14, wherein the subject is a living organism. 18. The method according to claim 14, wherein the object is an optical disk, and the area is an information-carrying area within and / or on the optical disk. 19. The method of claim 14, wherein step (c) comprises passing the probe beam through at least one diffraction grating, wherein the lines are substantially parallel to a main surface of the object. the method of. 20. The method of claim 14, wherein the line of step (c) is substantially perpendicular to a main surface of the object. 21. The method according to claim 14, comprising performing a Fourier transform on the data generated by the detector system. 22. An interferometer system for identifying a focused image of an area within and / or on an object from an out-of-focus image so as to reduce errors in image information of the object, comprising: (a) a probe beam; And a point light source for generating a reference beam; (b) a first phase shifter for producing an antisymmetric spatial characteristic in the reference beam; and (c) a focused image point in or on the area of the probe beam. (D) a second phase shifter for producing an anti-symmetric spatial characteristic in the focus returning probe beam; and (e) the opposite. The anti-symmetric reference beam and the anti-symmetric focus beam to cause the reference beam to interfere with the beam from the out-of-focus image point and the anti-symmetric reference beam to interfere with the anti-symmetric focusing return probe beam. A second beam guiding device for guiding a return probe beam; and (f) a detector system for detecting an interference term between the anti-symmetric reference beam and the anti-symmetric focusing return probe beam; An interferometer, wherein the amplitude of an interference term between the amplitude of the image beam and the amplitude of the anti-symmetric reference beam is substantially reduced to reduce errors in data generated by the detector system and to represent image information. system. 23. The interferometer system according to claim 22, wherein the point light source is a point of a line light source. 24. The interferometer system according to claim 22, wherein the point light source is a single point light source. 25. The interferometer system according to claim 22, wherein the point light source is a point of a broadband point light source. 26. An interferometer system for identifying a focused image of an area within and / or on an object from an out-of-focus image to reduce errors in image information of the object, comprising: (a) a probe beam; A point light source for generating a reference beam; and (b) a first phase shifter for producing an antisymmetric spatial characteristic in the reference beam; and (c) a first dispersive element, and the probe beam in the object and Or a first beam guide for passing the probe beam through the first dispersive element to convert it into a beam focused on a line on the object, thereby producing a refocused probe beam; d) a second phase shifter for producing an anti-symmetric spatial characteristic in the focusing return probe beam; and (e) spatial filtering the anti-symmetric focusing return probe beam. (F) a second dispersive element, and a spatially filtered antisymmetric focusing return probe beam to convert the beam into a beam focused to a line in the detector plane of a detector system. (G) the spatial filter further spatially filters the antisymmetric reference beam, and (h) the second beam guiding device for passing the focus returning probe beam through the second dispersive element. A beam guide for passing the reference beam through the second dispersive element to convert the spatially filtered antisymmetric reference beam into a beam focused on a line in the detector plane; The spatial filter further spatially filters the beam from the out-of-focus image point; and (j) the second beam guide further spatially filters the beam. Passing the beam from the out-of-focus image point through the second dispersive element to convert the beam from the out-of-focus image point into a beam focused on a line in the detector plane; A detector system detects an interference term between the spatially filtered and focused anti-symmetric reference beam and the spatially filtered and focused anti-symmetrically focused return probe beam, and spatially filtered and focused. The amplitude of the interference term between the amplitude of the out-of-focus beam and the amplitude of the spatially filtered and focused anti-symmetric reference beam reduces errors in the data generated by the detector system and An interferometer system that is substantially reduced to represent an image. 27. The interferometer system according to claim 26, wherein the point light source is a point of a line light source. 28. The interferometer system according to claim 26, wherein the point light source is a single point light source. 29. The interferometer system according to claim 26, wherein said point light source is a broadband point light source. 30. An interferometer system for identifying a focused image of an area within and / or on an object from an out-of-focus image so as to reduce errors in image information of the object, comprising: (a) a probe beam; A point light source for generating a reference beam; (b) a first phase shifter for producing an antisymmetric spatial characteristic in the reference beam; and (c) placing the probe beam within the object to generate a focus returning probe beam. And / or a focusing device for converting the beam into a beam focused on a line on the object; (d) a second phase shifter for producing an anti-symmetric spatial characteristic in the focus returning probe beam; A spatial filter for spatially filtering the nominally focused return probe beam; (f) a dispersive element; and the spatially filtered antisymmetrically focused return probe beam. A beam guiding device for passing the refocused probe beam through the dispersive element to convert the beam into a beam focused on a line in the detector plane of the detector system; and (g) the spatial filter further comprises the anti-symmetric Spatially filtering the reference beam; (h) the beam director further converts the spatially filtered antisymmetric reference beam into a beam focused to a line in the detector plane. (I) the spatial filter further spatially filters the beam from the out-of-focus image point; and (j) the beam guide device directs the spatially filtered beam from the out-of-focus image point. A beam from the out-of-focus image point is passed through the dispersive element to convert it to a beam focused on a line in the detector plane. (K) the detector system detects an interference term between the spatially filtered and focused antisymmetric reference beam and the spatially filtered and focused antisymmetric focusing return probe beam; The amplitude of the interference term between the spatially filtered and focused out-of-focus beam amplitude and the spatially filtered and focused anti-symmetric reference beam amplitude determines the error in the data generated by the detector system. An interferometer system, wherein the interferometer system is substantially reduced to represent an image of the object. 31. The interferometer system according to claim 30, wherein the point light source is a point of a line light source. 32. The interferometer system according to claim 30, wherein the point light source is a broadband point light source. 33. A lithographic system for use in manufacturing integrated circuits on a wafer, comprising: (a) a stage for supporting the wafer; and (b) a spatially patterned substrate on the wafer. An illumination system for imaging the emitted radiation; (c) a wafer with an alignment area within and / or on the wafer; and (d) positioning the stage with respect to the imaged radiation. A laser gauge control positioning system for adjusting; and (e) within and within the object to reduce errors in image information of the object connected to the laser gauge control positioning system for measuring a relative position of the alignment area. Or an interferometer system for identifying a focused image of a region on the object from an out-of-focus image. Raffy system. 34. A lithographic system according to claim 33, comprising the interferometer system of claim 22. 35. A lithographic system according to claim 33, comprising the interferometer system of claim 26. 36. A lithographic system according to claim 33, comprising the interferometer system of claim 30. 37. A metrology system for use in inspecting an integrated circuit pattern on a wafer during the manufacture of an integrated circuit, comprising: (a) a stage for supporting the wafer; And / or a laser gauge controlled positioning system for adjusting the relative position of regions on the pattern; and (c) focusing of regions within and / or on the pattern to reduce errors in image information of the pattern. A metrology system comprising: an interferometer system for distinguishing the combined image from the out-of-focus image. 38. A metrology system according to claim 37, comprising the interferometer system of claim 22. 39. A metrology system according to claim 37, comprising the interferometer system of claim 26. 40. A metrology system according to claim 37, comprising the interferometer system of claim 30. 41. A metrology system for use in inspecting a pattern in a mask used during the manufacture of an integrated circuit, comprising: (a) a stage for supporting the mask; and (b) the mask. A laser gauge controlled positioning system for adjusting the relative position of an area within and / or on the mask; and (c) an area within and / or on the mask to reduce errors in image information of the pattern. An interferometer system for distinguishing the focused image from the out-of-focus image; and a metrology system comprising: 42. A metrology system according to claim 41, comprising the interferometer system of claim 22. 43. A metrology system according to claim 41, comprising the interferometer system of claim 26. 44. A metrology system according to claim 41, comprising the interferometer system of claim 30.