JP2918992B2 - Detector of amplitude image using heterodyne detection light receiving system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting an amplitude image separated from a scattered component and an incoherent optical signal, and more particularly to an apparatus using a heterodyne detection light-receiving system for that purpose.

[Conventional technology]

Since the discovery of X-rays, techniques for observing the inside of a living body (human body) from outside without damaging it (pessimistic or non-invasive measurement methods) have been strongly sought and developed in biology, especially in the field of medicine. . In this technique, gamma rays and X-rays having the shortest wavelengths and radio waves having the longest wavelengths are used as electromagnetic waves. The former is an X-ray CT, and the latter is an NMR-CT (Magnet
tic Resonance Imaging (MRI).

On the other hand, ultraviolet, which is widely used in the fields of physics and chemistry,
There are relatively few attempts to apply spectroscopy in the visible-near-infrared-infrared region to "whole" organisms (in vivo). This is because many problems concerning the most basic "quantitative property" remain without being solved in biological measurement using light, particularly in those utilizing absorption and emission processes. At present, measurement using a reflection spectrum measuring device using a solid-state element, a high-sensitivity TV camera, or the like is being attempted, but it is for this reason that the reproducibility and the obtained absolute value are less reliable.

When illuminating a scatterer such as a living tissue with light, it is possible to extract a certain amount of straight light by receiving the light in a 180-degree face-to-face relationship, but at present the spatial resolution is not very good.

At present, the difference in spatial resolution between X-rays and light cannot be bridged. However, the use of light, especially near-infrared light, should allow imaging of tissue oxygen concentration from hemoglobin in blood. These are other NMR-CT and X-ray C
Will give you different information than T.

With a tissue 3-5 cm thick, we can detect transmitted light. This means that "light-radiography" can be used for diagnosis. Women's breasts have relatively uniform tissue and are easy to transmit light, and their shape makes it easy to detect transmitted light (thickness: about 3 cm). Diaphanography (Lights
canning).

Under such circumstances, the present inventor has made Japanese Patent Application No. 63-3046.
No. 91, Japanese Patent Application No. 1-250036, the coherent light component having a different frequency from the coherent light component is used to separate and detect the coherent light component containing the absorption information and containing the scattered light. We propose to use an optical heterodyne detection and reception system that combines the light and detects the beat component of the combined light.

[Problems to be solved by the invention]

However, according to the above proposal, in order to obtain a two-dimensional amplitude image of the sample, it is necessary to scan the sample with coherent irradiation light relative to the sample, and before or after combining the two lights. A high directivity optical system that cuts the scattered component is inserted into the sample, and the beat component of the two lights is detected at or near the object plane immediately after the light transmitted through the sample.

The present invention has been made in view of such a situation, and its object is a device that detects an amplitude image by separating it from a scattered component and an incoherent optical signal using an optical heterodyne detection light receiving system. It is an object of the present invention to provide a device that complements the device proposed in the previous proposal.

[Means for solving the problem]

To achieve the above object, a first apparatus for detecting an amplitude image using a heterodyne detection light-receiving system according to the present invention irradiates a sample with coherent light and combines the transmitted light with the reference coherent light having a different frequency from the coherent light. An apparatus for detecting an amplitude image of a sample by optical heterodyne detection,
By irradiating uniform parallel coherent light onto the entire surface of the sample, combining the transmitted light of the sample and the reference coherent light, and detecting a one-dimensional or two-dimensional beat component in the cross section of the synthesized light beam, the amplitude image of the sample is obtained. In the amplitude image detection apparatus using the heterodyne detection light receiving system configured to obtain the reference coherent light and the transmitted light over the entire cross section of the light beam transmitted through the sample, one is included in the combined light beam cross section.
One or more two-dimensional photodetector arrays are arranged and each photodetector detects a beat component at a corresponding photodetector element position, thereby obtaining an amplitude image of the sample. It is.

In such a case, the cross section of the combined light beam is divided into small areas, a condenser lens is arranged in each divided area, and each light detection element of the light detection element array is arranged at the condensing position of each condenser lens, and each light detection is performed. An amplitude image of the sample may be obtained by detecting a beat component of each corresponding divided region by an element.

An amplitude image detecting apparatus using the second heterodyne detection light receiving system of the present invention irradiates a sample with coherent light, combines the transmitted light with the reference coherent light having a different frequency from the coherent light, and performs optical heterodyne. In a device for detecting an amplitude image of a sample by detection, a uniform Fourier transform optical system that irradiates uniform parallel coherent light to the entire surface of the sample and Fourier-transforms the amplitude distribution of the transmitted light of the sample is arranged. And an amplitude distribution spectrum of the transmitted light, and a beat component in a one-dimensional or two-dimensional direction on a spectrum surface is detected to obtain an amplitude image of the sample. .

Also in this case, in order to combine the reference coherent light and the spectrum of the amplitude distribution of the transmitted light, the reference coherent light and the spectrum of the amplitude distribution of the transmitted light are combined over the entire spectrum surface, and one-dimensional or two-dimensional By detecting the beat component in the dimensional direction or by synthesizing the reference coherent light and the spectrum of the amplitude distribution of the transmitted light at a part of the spectral surface, and detecting the beat component of the synthesized light, It is possible to configure so as to detect a spectral component corresponding to the combined position, and to scan the combined position in a spectrum plane to obtain an amplitude image of the sample.

Then, a spatial filter is arranged on the spectral surface, and a one-dimensional or two-dimensional beat component of the combined light beam that has passed through the spatial filter is detected, or a one-dimensional or two-dimensional beat component on the spectral surface is detected. By performing the filtering process for each detected and detected spectral component, image processing can be performed on the detected amplitude image.

Further, the amplitude image detecting apparatus using the third heterodyne detection light receiving system of the present invention irradiates the sample with coherent light, synthesizes the transmitted light and the reference coherent light having a different frequency from the coherent light, In a device for detecting an amplitude image of a sample by optical heterodyne detection, a first Fourier transform optical system configured to irradiate uniform parallel coherent light to the entire surface of the sample and to perform a Fourier transform on an amplitude distribution of transmitted light of the sample, A second Fourier transform optical system for further Fourier transforming the distribution on the spectrum plane is arranged, and the reference coherent light and the re-converted light are combined on the transform plane of the second Fourier transform optical system to form a second Fourier transform. A configuration in which an amplitude image of the sample is obtained by detecting a one-dimensional or two-dimensional beat component on the conversion surface of the conversion optical system. It is an butterfly.

In the case of this arrangement, a spatial filter is arranged on the spectrum plane, and a one-dimensional or two-dimensional direction beat component between the light passing through the spatial filter and the reference coherent light is detected. It is desirable to apply.

Also in this case, to combine the reference coherent light and the re-converted light, the reference coherent light and the re-converted light are combined over the entire conversion surface of the second Fourier transform optical system, and the one-dimensional or two-dimensional cross section of the combined light flux is obtained. The beat component in the dimensional direction is detected, or the reference coherent light and the re-converted light are combined at a part of the conversion surface of the second Fourier transform optical system,
By detecting the beat component of the combined light, it is configured to detect the amplitude transmittance of the sample corresponding to the combined position, and by scanning the combined position in the conversion plane,
It can be configured to obtain an amplitude image of the sample.

[Action]

According to the first invention, the reference coherent light and the transmitted light are combined over the entire cross section of the light beam transmitted through the sample, and a one-dimensional or two-dimensional array of photodetector elements is arranged in the cross section of the combined light beam. By detecting the beat component at the corresponding light detection element position by the detection element, the amplitude image of the sample is obtained, so that the scattering component and the incoherent light signal can be obtained without moving the sample for scanning. And the amplitude image of the sample can be easily detected with high accuracy.

According to the second aspect of the present invention, a uniform Fourier transform optical system for irradiating uniform parallel coherent light to the entire surface of the sample and Fourier transforming the amplitude distribution of the transmitted light of the sample is arranged. By combining the amplitude distribution spectrum and the one-dimensional or two-dimensional beat component on the spectrum plane, it is possible to detect the beat component from the scattered component and the incoherent optical signal without moving the sample for scanning. The separated amplitude image of the sample can be easily detected with high accuracy, and furthermore, image processing can be performed on the detected amplitude image to improve contrast and the like.

Similarly, according to the third aspect, a first Fourier transform optical system configured to irradiate uniform parallel coherent light to the entire surface of the sample and Fourier-transforming the amplitude distribution of the transmitted light of the sample, and the distribution on the spectrum surface And a second Fourier transform optical system that further performs Fourier transform of the second Fourier transform optical system, and combines the reference coherent light and the re-converted light on the conversion surface of the second Fourier transform optical system to convert the second Fourier transform optical system. Since the one-dimensional or two-dimensional beat component on the surface is detected, the amplitude image of the sample can be separated with high precision by separating the sample from the scattering component and the incoherent optical signal without moving the sample for scanning. Detection can be easily performed, and furthermore, the detected amplitude image can be subjected to spatial filtering image processing to improve contrast and the like.

〔Example〕

In the heterodyne detection light receiving system, if the diameter of the light receiving surface of the detector (when taking a beat at the light condensing point, the aperture diameter of the light condensing optical system) is d, and the wavelength of the light to be detected is λ, the angular resolution is Is approximately d / λ. Therefore, if the diameter d of the light receiving surface of the detector is made sufficiently large compared to the wavelength λ of the light to be detected, the high directivity optical system can be used without using it.
A light receiving system with high directivity can be configured. Examples are shown in FIG. 1 to FIG. In FIG. 1, a sample S whose transmittance changes depending on the location (in the drawing, a waveform such as a phase distribution is shown, but it is assumed that the transmittance distribution is shown) and a scatterer N located around the sample S Is illuminated with parallel coherent light I such as laser light. A half mirror HM is inserted into the transmitted light optical path, and is synthesized with a coherent local light I ′ having a constant intensity slightly different in frequency from the illumination light I. The combined light is condensed by the lens L, photoelectrically converted by the detector D, and a signal is obtained in which the beat component of the frequency difference between the illumination light I and the local light I 'is superimposed on the DC component. Since the intensity of the beat component is proportional to the amplitude of the light transmitted through and absorbed by the sample S, the average amplitude transmittance in the illumination area of the sample S can be obtained. On the other hand, even if the light scattered by the scatterer N and represented by the dotted line are mixed with the local light I ', no beat component is generated on the detector D, but a direct current component. By separating and detecting the beat component of the signal from the light source, it is possible to extract and detect the amplitude intensity of only the light in the straight traveling light direction with high directivity. In order to obtain a two-dimensional amplitude transmittance distribution (amplitude image of the sample) of the sample S, the above-described detection may be performed while scanning the sample S two-dimensionally in a direction perpendicular to the optical axis. Note that the lens L is not always necessary, and a pinhole P for cutting scattered light or the like may be arranged in front of the detector D. In the case of FIG. 2, the illumination light I is once condensed on the sample S by the condensing lens L1, the transmitted spherical wave and the spherical wave local light I1 'are combined by the half mirror HM1, and the beat component is Detector D1 is used for detection, or light transmitted through sample S is converted into parallel light by lens L2, and then combined with plane wave local light I2 'and half mirror HM2 to detect detector D.
2 is to be detected. This is due to the fact that a beat component is obtained which is equivalent to the case where the lens is converted into a plane wave by the lens for heterodyne detection and the case where the heterodyne detection is performed by the spherical wave, and the conditions required for wavefront matching are equal. The rest is the same as in FIG.
Next, the one shown in FIG. 3 does not move the sample S for scanning, but moves a part of the optical system to move the sample S.
This is an arrangement for obtaining the same operation as scanning. Coherent light from laser 1 is beam splitter BS
, One of which is expanded into a beam larger than the diameter of the sample S by the beam expander BE to illuminate the sample S. The other beam split into two beams enters a frequency shifter AO such as an ultrasonic modulator via a mirror M1 and is slightly shifted in frequency, and is scanned in two-dimensional directions in the direction indicated by the double arrow and the direction perpendicular to the plane of the drawing. The scanning is performed two-dimensionally by the scanning mirror M2.
The two beams combined by the half mirror HM are photoelectrically converted by a detector D which is scanned in two-dimensional directions in the directions indicated by both arrows and perpendicular to the paper in synchronization with the scanning mirror M2, and a beat component is obtained. And the sample 2
A dimensional amplitude image is required. The symbol PO arranged before the detector D indicates a polarizer, and reduces noise to reduce S / N.
The sensitivity is improved by inserting. The other beam can be expanded by the beam expander BE so as to scan the illumination light.

As described above, using the heterodyne detection light receiving system,
The two-dimensional or one-dimensional amplitude image of the sample S can be obtained by relatively scanning the sample S and detecting the two-dimensional amplitude image of the sample S without moving any of the sample S and the optical system. Can be detected. The basic arrangement for that is shown in FIG. In this case, the parallel coherent light I illuminating the sample S from behind is expanded to a beam larger than the diameter of the sample S, and the local light I 'is expanded similarly. The straight light and the local light I ′ transmitted through the sample S are a half mirror HM having a large area.
Detector 2 that detects the combined light.
In this case, is not a detector that simply detects the intensity of incident light, but a one-dimensional or two-dimensional detector in which a number of unit detection elements DO are arranged in one-dimensional or two-dimensional directions. Therefore, the light incident on each unit detecting element DO is the combined light of the light transmitted through the region of the sample S corresponding to the unit detecting element DO and the corresponding part of the local light I ′, and the beat component thereof is the sample. S is proportional to the amplitude transmittance of that region. In this case, the one-dimensional or two-dimensional detector 2
As the distance between the sample and the surface of the sample S increases, the minimum spatial sampling area of the image detected by the unit detection element DO increases. Further, when the density is increased by reducing the size of the unit detection element DO, not only the sampling area is increased, but also the sampling area is overlapped. Therefore, it is necessary to reproduce an image in consideration of the overlap. By subtracting the overlap, the minimum spatial resolution area becomes smaller, resulting in higher resolution. In the case of FIG. 5, unlike the case of FIG. 4,
A micro-lens ML is arranged at a position behind the sample S corresponding to each unit detecting element DO, and light transmitted through the sample is spatially sampled by the micro-lens ML and each unit detecting element
It is designed to be incident on DO. The local light I 'may be incident on the unit detection element DO as a plane wave as shown in the figure, and converted into a spherical wave similar to the light from the lens ML and incident as the local light I1' in FIG. You may make it do.

Some specific examples of an apparatus for detecting an amplitude image of a sample mixed with scattered light by a heterodyne detection light receiving system using a one-dimensional or two-dimensional detector instead of the movable part as described above will be described. The apparatus shown in FIG. 6 shows the structure of an apparatus for realizing the principle shown in FIG.
Is split into two by a beam splitter BS, one beam is used as illumination light I for illuminating the sample S from behind, and the other beam is transmitted through a mirror M1 to an ultrasonic modulator. Etc. frequency shifter
The light is incident on AO, the frequency is slightly shifted, and becomes the local light I ′ via the mirror M2. Note that a beam expander may be inserted before the beam splitter BS in order to increase the diameter of the light beam from the laser 1. The two beams I and I 'synthesized by the half mirror HM are incident on the one-dimensional or two-dimensional detector 2 via the polarizer PO, and the sampling area is sampled by the size of the unit detecting element, and the sampling is performed by the gap. The gap is fixedly sampled, and a signal in which a beat component proportional to the average amplitude transmittance of each sampling region of the sample S is superimposed on the DC component is obtained from each unit detection element. From the signals from each unit detection element, only the beat component is extracted through the band-pass filter 3 in which the center frequency is set to the shift frequency of the frequency shifter AO. Alternatively, a two-dimensional amplitude image is displayed. The thing of FIG. 7 is the device of FIG.
Similar beam expanders BE1 and BE2 are inserted in the optical path of the light transmitted through the sample S and in the optical path of the local light to enlarge the diameter of the light beam incident on the one-dimensional or two-dimensional detector 2, and obtain the obtained amplitude. The arrangement is such that the image is enlarged, and is an arrangement suitable for a minute sample S. In FIG. 8, conversely, beam reducers BC1 and BC2 are inserted in both optical paths to reduce the obtained amplitude image.

Incidentally, a component scattered from the sample S in a direction other than the straight traveling direction may have coherence with the incident light. The apparatus can be modified so that the amplitude distribution of components other than the straight-coupling light having such coherence can be detected. An example is shown in FIG. The only difference from the apparatus shown in FIG. 6 is that the position of the one-dimensional or two-dimensional detector 2 is set to a position for taking in a scattered component in a direction to be detected other than the straight light, and a half-wave is set so that local light is also incident on this position. This is the point where the mirror HM is arranged. In addition, the amplitude of the coherent light of the illumination light from the focal point in the sample S may have direction dependency. In such a case, as shown in FIG. 10, through the same optical path as in FIG.
A one-dimensional or two-dimensional detector 2 may be arranged as a detector to detect the amplitude distribution in each direction.

In the above description, an amplitude image is detected by detecting the beat components of two lights at or near the object surface immediately after the light transmitted through the sample. The Fourier transform spectrum signal of the amplitude image is converted to the spectrum of the object. It is also possible to detect by surface. As is well known, when an object is placed on the front focal plane of a lens and illuminated with coherent light, a Fourier transform of the amplitude distribution of the object is obtained on the rear focal plane of the lens, and similarly illuminated with incoherent light. In this case, and the incoherent scattered light from the object, the power spectrum of the object is obtained. This is schematically shown in FIG. If local light having a frequency different from the frequency of the illumination light is made incident simultaneously to try to take a beat by heterodyne detection on such a spectral plane, the free-lier transformed signal by the coherent illumination light produces a beat component proportional to the amplitude, Since the incoherent power spectrum does not generate a beat even when combined with the local light, it is possible to separate them from each other on the spectrum surface and extract only the signal based on the coherent light. The basic configuration for that is shown in FIG. When the sample S is arranged on the front focal plane of the convex lens L, the detection plane of the one-dimensional or two-dimensional detector 2 is arranged on the spectrum plane F which is the rear focal plane, and the sample S is illuminated with the coherent light I, the spectrum becomes On the surface F, a spectrum obtained by two-dimensionally Fourier-transforming the amplitude image of the sample S is obtained. A local light I ′ is applied to this spectrum plane F via a half mirror HM.
At the same time, a signal containing a beat component proportional to the amplitude of the position is obtained from each unit detecting element of the one-dimensional or two-dimensional detector 2, so that only this beat component is obtained for each unit detecting element. , Only the Fourier transform component of the amplitude image of the sample S can be detected. Although this detection signal represents the spatial frequency distribution of the amplitude image of the sample S, in order to directly obtain the amplitude image of the sample S, the detection signal may be electrically subjected to Fourier transform again. In the figure, the element 10 arranged in front of the detection surface of the one-dimensional or two-dimensional detector 2 is proposed in Japanese Patent Application Nos. 1-62898, 1-250034 and 2-77690. 1 shows a highly directional optical system, which is used to reduce noise by limiting the direction of light incident on each unit detection element of the one-dimensional or two-dimensional detector 2. This highly directional optical system
10 is not necessary. By the way, in order to obtain a spatial Fourier transform of the amplitude distribution of the sample S, the illumination with the coherent light I does not necessarily need to be a transmitted illumination from the optical axis direction as shown in FIG. As shown in FIG. 13, illumination can be performed from an oblique direction with respect to the optical axis. The right side of FIG. 13 shows the spectrum due to the incoherent light appearing on the spectrum plane F and the spectrum due to the coherent light hidden in the spectrum. According to the principle of the present invention, even in such a case, Only the spectrum due to the coherent light can be separated and extracted.

By the way, even if a simple detector is used instead of a one-dimensional or two-dimensional detector, a Fourier transform spectrum signal of an amplitude image can be detected on a spectrum surface. Example
It is shown in Figure 14. The spectrum Fourier-transformed by the lens L is combined with the local light I ′ whose position is moved on the spectrum plane F by the half mirror HM moving in the directions of both arrows on the plane of the drawing and the direction perpendicular to the plane of the drawing. By converting the signal into a signal including a beat component and obtaining a two-dimensional distribution of the beat component, a Fourier transform of the amplitude of the sample S can be detected on the spectrum plane F.

By the way, according to the optical two-dimensional Fourier transform method using coherent light, the zero-order component of the spectrum plane F carries only information on the brightness of the image and does not include image information. Then, when the image is reproduced, an image having a spatial frequency twice as high is obtained, and an image equivalent to a reduced image is obtained. However, since the DC component of the image disappears,
Reconstructing the image improves the contrast. Further, it is possible to change the characteristics of the reproduced image by passing only the spectral component of a specific frequency, cutting the spectrum component in reverse, or changing the attenuation factor for each frequency. Such processing is called spatial filtering. For that purpose, a spatial filter having desired characteristics may be inserted into the spectral plane F. In FIG. 15 (a), a zero-order component cut filter 7 is inserted in front of the detection surface of the one-dimensional or two-dimensional detector 2 so as to cut the zero-order component in the spectrum of the sample to be detected. It is. The processing order of image reproduction in this case is shown in FIG. The image reproduction is performed by using the zero-order component cut filter 7 from the spectrum of the coherent light.
, And the one-dimensional or two-dimensional detector 2 and the band-pass filter 3 perform heterodyne detection to detect a two-dimensional beat component. The signal is subjected to two-dimensional Fourier transform by the calculator 5 and re-developed. Get. In the re-development, the contrast is improved as described above. Thus, instead of inserting an optical spatial filter into the spectral plane, it is possible to do the same electrically. That is, in FIG. 15 (a), without using the filter 7, the processing of the procedure as shown in FIG. 15 (c) is performed electrically. A signal based on the coherent light on the spectrum surface is directly detected as a two-dimensional beat component by heterodyne detection, and the zero-order component is cut by a calculator 5,
Thereafter, two-dimensional Fourier transform is performed to obtain redevelopment. In the above description, the spectrum signal detected by the heterodyne detection on the spectrum plane F is Fourier-transformed to reproduce the image. However, the Fourier-transformed spectrum signal of the amplitude image of the sample S on the spectrum plane is used as it is. Of course, you can.

Now, instead of detecting the Fourier transform spectrum of the amplitude image on the spectrum surface by the heterodyne detection light receiving system of the present invention and electrically reproducing the signal and performing a filtering process on the signal, instead of reproducing the image, As shown in FIG. 16, the Fourier transform for image reproduction is optically performed by the second convex lens L2, and heterodyne detection is performed on the image plane to remove components due to incoherent light due to scatterers. An amplitude image obtained by performing image processing on S is obtained. Note that by the focal length f ₂ and the different sizes of the focal length f ₁ and the lens L2 of the lens L1, can be reduced or enlarged reproduced image with respect to the sample. When f ₁ > f ₂ , the image is reduced, and when f ₁ <f ₂ , the image is enlarged. Also, as in the case of FIGS. 3 and 14, a simple detector is used instead of the one-dimensional or two-dimensional detector, and the local light to be synthesized is scanned on the detection surface so that the one-dimensional or two-dimensional beat component is scanned. Can be obtained.

The embodiments of the amplitude image detecting apparatus using the heterodyne detection light receiving system of the present invention have been described above. However, the present invention is not limited to these embodiments, and various modifications are possible. For example, as a frequency shifter, not only those using ultrasonic light diffraction such as an ultrasonic modulator,
In addition to the combination of the wave plates and the rotating grating, the electro-optic effect of the crystal can be used. Further, the reflecting mirror may be moved at a constant speed or vibrated by a sawtooth wave. Furthermore, although the above discussion has been described on the assumption that light is used, it goes without saying that the same can be applied to infrared, ultraviolet, and microwave regions.

[Effect of the Invention] In the amplitude image detecting apparatus using the first heterodyne detection light receiving system of the present invention, the reference coherent light and the transmitted light are combined over the entire cross section of the light beam transmitted through the sample, and the cross section of the synthesized light beam is obtained. A one-dimensional or two-dimensional array of photodetector elements is arranged in the device, and a beat component at a corresponding photodetector element position is detected by each photodetector element to obtain an amplitude image of the sample. Even if the sample is not moved for scanning, the amplitude image of the sample can be easily detected with high precision by separating it from the scattered component and the incoherent optical signal.

Further, in the amplitude image detecting apparatus using the second heterodyne detection light receiving system of the present invention, a Fourier transform optical system for irradiating uniform parallel coherent light over the entire surface of the sample and Fourier transforming the amplitude distribution of the transmitted light of the sample. Are arranged in the spectrum plane, and the spectrum of the amplitude distribution of the reference coherent light and the transmitted light is synthesized in the spectrum plane, and 1 in the spectrum plane is synthesized.
One-dimensional or two-dimensional beat components are detected, so even if the sample is not moved for scanning, the amplitude image of the sample can be easily detected with high precision by separating it from the scatter component and the incoherent optical signal. In addition, image processing can be performed on the detected amplitude image to improve the contrast and the like.

Further, in the amplitude image detecting apparatus using the heterodyne detection light receiving system according to the third aspect of the present invention, the entire surface of the sample is irradiated with uniform parallel coherent light, and the amplitude distribution of the transmitted light of the sample is Fourier transformed. A first Fourier transform optical system and a second Fourier transform optical system for further Fourier transforming the distribution on the spectral surface thereof are arranged.
Since the reference coherent light and the re-converted light are combined on the conversion surface of the Fourier transform optical system to detect a one-dimensional or two-dimensional beat component on the conversion surface of the second Fourier transform optical system. Even if the sample is not moved for scanning, the amplitude image of the sample can be easily detected with high accuracy by separating it from the scattered component and the incoherent optical signal. Processing can be performed to improve contrast and the like.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram for explaining a hetero-die detection light-receiving system for detecting the amplitude intensity of a sample using parallel illumination light, and FIG. 2 is a diagram illustrating the amplitude intensity of the sample using condensed illumination light. FIG. 3 is a diagram for explaining a hetero-die detection light-receiving system for detection, FIG. 3 is a diagram for explaining a hetero-die detection light-receiving system for detecting the amplitude intensity of a sample using expanded parallel illumination light, and FIG. 4 is one-dimensional or two-dimensional. FIG. 5 is a diagram showing a basic arrangement of a hetero dye detection light receiving system for detecting an amplitude image of a sample using a dimensional detector, FIG. 5 is a diagram showing a modification of FIG. 4, and FIG. 6 is a diagram showing the principle shown in FIG. FIG. 7 is a diagram showing a configuration of an apparatus embodying the present invention, FIG. 7 is a diagram showing a configuration of a device modified so as to enlarge the amplitude image obtained in the device of FIG. 6, and FIG. FIG. 9 is a diagram showing a configuration of an image obtained by deforming an amplitude image to be reduced, The figure shows the configuration of a device modified to detect the amplitude distribution of components other than straight light, and FIG. 10 shows the case where the amplitude of coherent light from the focal point of the illumination light has direction dependency. FIG. 11 is a diagram showing a configuration of a device modified so that dependency can be detected,
The figure is a schematic diagram for explaining the spectrum appearing on the rear focal plane of the lens, FIG. 12 is a diagram showing the basic configuration of an amplitude image detecting device for hetero-dy detection on the spectrum surface, and FIG. 13 is for explaining the deformation of the illumination direction. FIG. 14 is a view showing a configuration of a modification of the apparatus of FIG. 12, and FIG. 15 is a view for explaining an image reproduction principle when image processing is introduced in an amplitude image detection apparatus for hetero-dy detection on a spectrum plane. FIG. 16 is a diagram showing a basic configuration of an amplitude image detecting apparatus for performing hetero-dy detection on an image plane. 1 ... laser, 2 ... one-dimensional or two-dimensional detector, 3 ...
... band pass filter, 4 ... display device, 5 ... calculator, 7 ... spatial filter, 10 ... high directivity optical system, S
... sample, N ... scatterer, I ... illumination light, I ', I1',
I2 ': Local light, HM, HM1, HM2: Half mirror, L,
L1, L2: convex lens, D, D1, D2: detector, P: pinhole, BS: beam splitter, BE, BE1, BE2 ...
… Beam expander, M1, M2… Mirror, AO… Frequency shifter, PO… Polarizer, DO… Unit detection element, ML… Micro lens, BC1, BC2… Beam reducer, F… Spectrum surface

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Fumio Inaba 1-13-1 Minami Yagiyama, Taishiro-ku, Sendai City, Miyagi Prefecture (56) References JP-A-58-140338 (JP, A) JP-A-62-263427 ( JP, A) JP-A-2-110346 (JP, A) JP-A-2-110348 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01N 21/00-21/01 G01N 21/17-21/61 A61B 10/00 JOIS

Claims (11)

(57) [Claims] An apparatus for irradiating a sample with coherent light, combining the transmitted light with reference coherent light having a different frequency from that of the coherent light, and detecting an amplitude image of the sample by optical heterodyne detection, comprising: The entire surface is irradiated with uniform parallel coherent light, the transmitted light of the sample and the reference coherent light are combined, and one-dimensional or two-dimensional
In an amplitude image detecting apparatus using a heterodyne detection light receiving system configured to obtain an amplitude image of a sample by detecting a beat component in a dimensional direction, the reference coherent light and the transmitted light are transmitted over the entire cross section of the light beam transmitted through the sample. And a one-dimensional or two-dimensional array of photodetector elements arranged in the cross section of the synthesized light beam, and a beat component at the corresponding photodetector element position is detected by each of the photodetector elements, thereby obtaining an amplitude image of the sample. An amplitude image detection apparatus using a heterodyne detection light receiving system, wherein the amplitude image is detected. 2. A method according to claim 1, wherein the cross section of the combined light beam is divided into small areas, a condenser lens is arranged in each divided area, and each light detection element of the light detection element array is arranged at a light condensing position of each condenser lens. 2. The amplitude image detection using a heterodyne detection light receiving system according to claim 1, wherein the amplitude component of the sample is obtained by detecting the beat component of each corresponding divided region by each light detection element. apparatus. 3. An apparatus for irradiating a sample with coherent light, combining the transmitted light with reference coherent light having a different frequency from the coherent light, and detecting an amplitude image of the sample by optical heterodyne detection. A uniform parallel coherent light is irradiated, a Fourier transform optical system for Fourier transforming the amplitude distribution of the transmitted light of the sample is arranged, and the reference coherent light and the amplitude distribution spectrum of the transmitted light are combined on the spectrum surface, and the spectrum is synthesized. By detecting the one-dimensional or two-dimensional beat component on the surface,
An amplitude image detection apparatus using a heterodyne detection light receiving system, wherein the amplitude image detection apparatus is configured to obtain an amplitude image of a sample. 4. An amplitude image of a sample is synthesized by synthesizing a reference coherent light and a spectrum of an amplitude distribution of transmitted light over the entire spectrum surface and detecting a one-dimensional or two-dimensional beat component of a cross section of the synthesized light beam. 4. An amplitude image detecting apparatus using a heterodyne detection light-receiving system according to claim 3, wherein the amplitude image is detected. 5. A method of combining a reference coherent light and a spectrum of a transmitted light amplitude distribution at a part of a spectral plane,
It is configured to detect a spectral component corresponding to a synthesized position by detecting a beat component of the synthesized light, and to scan an amplitude image of a sample by scanning the synthesized position in a spectrum plane. An apparatus for detecting an amplitude image using a heterodyne detection light receiving system according to claim 3. 6. An amplitude image of a sample is obtained by arranging a spatial filter on a spectrum surface and detecting a one-dimensional or two-dimensional beat component of a combined light beam passing through the spatial filter. An amplitude image detecting apparatus using the heterodyne detection light receiving system according to any one of claims 3 to 5. 7. The apparatus according to claim 3, wherein a beat component in a one-dimensional or two-dimensional direction on a spectral plane is detected, and filtering processing is performed for each detected spectral component. An amplitude image detection apparatus using the heterodyne detection light receiving system described in the above item. 8. An apparatus for irradiating a sample with coherent light, combining the transmitted light with the reference coherent light having a different frequency from the coherent light, and detecting an amplitude image of the sample by optical heterodyne detection. A first Fourier transform optical system configured to irradiate uniform parallel coherent light and Fourier-transformed the amplitude distribution of the transmitted light of the sample, and a second Fourier transform optical system configured to further Fourier-transform the distribution on its spectral plane And the reference coherent light and the re-converted light are combined on the conversion surface of the second Fourier transform optical system, and the one-dimensional or two-dimensional beat component on the conversion surface of the second Fourier transform optical system is calculated. An amplitude image detecting apparatus using a heterodyne detection light receiving system, wherein an amplitude image of a sample is obtained by detecting. 9. A spatial filter arranged on a spectral plane,
9. The heterodyne detection system according to claim 8, wherein an amplitude image of the sample is obtained by detecting a one-dimensional or two-dimensional beat component between the light passing through the spatial filter and the reference coherent light. An amplitude image detection device using a light receiving system. 10. The reference coherent light and the reconverted light are combined over the entire conversion surface of the second Fourier transform optical system,
10. An amplitude image using the heterodyne detection light receiving system according to claim 8, wherein an amplitude image of the sample is obtained by detecting a one-dimensional or two-dimensional beat component of the cross section of the combined light beam. Detection device. 11. A combination of reference coherent light and re-converted light at a position on a part of a conversion surface of a second Fourier transform optical system, and detection of a beat component of the combined light to obtain a combined position. 10. The apparatus according to claim 8, wherein the apparatus is configured to detect an amplitude transmittance of a corresponding sample, and to scan an amplitude image of the sample by scanning the combined position in a conversion plane. An amplitude image detection device using a heterodyne detection light receiving system.