JPH10267831A - Birefringence measuring optical system and high space resolution polarization analyzer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve space resolution and measure birefringence quantity of an object. SOLUTION: The birefringence measuring optical system is provided with a horizontal Zeeman laser 10 for stabilizing frequency and λ/2 wavelength plate 20 (polarization emission optical system) which emit a laser light to an object OB in a specified polarization state, a linear polarizing element 30 (polarization detection optical system) which detects as an optical signal a data such as difference of birefringence phase of the object OB, information on main axial direction and rotatory polarization angle which can be analyzed through polarization, through the object OB, and an optical detector 4 which converts the optical signal from the element 30 into an electric signal and detects it. An optical fiber 5 (light transmission route) is arranged between the optical detector 4 and object OB to pick up a part of light flux of optical signal from the object OB side toward the optical detector 4 side and send it through light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a birefringence measuring optical system and a high spatial resolution ellipsometer for measuring the amount of birefringence of an object such as a DVD disk and a liquid crystal display, and more particularly to a high spatial resolution ellipsometer. The invention relates to a novel optical configuration.

[0002]

2. Description of the Related Art In the multimedia industry, which is rapidly developing in recent years, there is a strong demand for higher density of recording media and higher precision of display devices as its elemental technologies. For example, in DVD discs, the recording signal density must be increased by lowering the birefringence and homogeneity of the material, and in the liquid crystal display, higher resolution must be achieved by shifting from SVGA to XGA. I have.

[0003] Therefore, as a material evaluation technique necessary to achieve such a problem, for example, the state of birefringence near a signal pit in the case of a DVD disk, the birefringence information in pixel units in the case of a liquid crystal display, and the like. Of particular interest is a quantitative birefringence measurement technique on a scale.

[0004] As such a birefringence measuring device, a polarizing microscope, a polarization analyzing device and the like are conventionally known. However, a polarizing microscope uses an optical microscope incorporating a polarizer and a phaser, and qualitatively and intuitively observes the state of birefringence distribution at a magnification corresponding to the combination of the objective lens and eyepiece. Yes, it can hardly be used in the quantitative measurement as described above.

The ellipsometer uses a rotation analyzer method, a phase compensation method, a Senarmont method, a phase modulation method, an optical heterodyne method, or the like, and has a configuration in which the entire light beam passing through the sample is received by a photodetector. Therefore, the spatial resolution is determined by the size and thickness of the light flux, and there is a restriction that the positional resolution in measurement is, for example, about 0.5 mm.

Therefore, as one of the attempts to quantitatively measure the birefringence by microscopic measurement, a method of adding a converging lens to the optical system of the above-mentioned ellipsometer and converging an optical signal on a sample using the lens is used. Is expected. In this method, the beam can pass through a very limited region of the sample, so that the spatial resolution can be further improved.

[0007]

However, in the ellipsometer using the convergent lens described above, although the spatial resolution on the sample surface is improved, the luminous flux in the light beam has a different incident angle to the sample. Therefore, there are the following problems.

FIGS. 32 (a) to 32 (c) illustrate how the birefringence changes due to the difference in the incident angle. Here, the birefringence of a sample such as a crystal or a polymer material exhibiting optical anisotropy is represented by refractive indices nx, ny, nz on the X, Y, and Z axes.
If we consider using a three-dimensional refractive index ellipsoid determined by, the difference between the observation direction, that is, between the major axis of the ellipse in the plane perpendicular to the observation direction through the origin of the refractive index ellipsoid and its minor axis The difference is the refractive index.

[0009] That is, a case where parallel light is vertically incident on such a sample as shown in FIG.
As shown in FIGS. 2B and 2C, the direction of the refractive index ellipsoid is different between the case where the light is obliquely incident, and the difference in the birefringence phase difference that the light receives is similar to the case where the above-described observation direction is different. .

Considering the case where convergent light is made incident using a lens system as shown in FIG. 33, for example, light beams A and B at different incident angles in the convergent light have different complexities from the sample. Because of the refraction phase difference, the amount of birefringence phase difference received by the entire convergent light is the sum of the phase differences received by each minute light beam when the light beam is divided into minute portions. Therefore, when the convergent light is incident on the sample, the incident angle of the light cannot be defined in a strict sense, and there has been a problem that the amount of birefringence of the sample cannot be accurately measured.

The present invention has been made in consideration of such conventional problems, and has as its object to accurately measure the amount of birefringence of an object while improving spatial resolution.

[0012]

In order to achieve the above-mentioned object, the present inventor has conducted various studies and considerations on a method for microscopic measurement of birefringence when parallel light is incident on a sample.

For example, as a method of reducing the beam diameter of the laser light while keeping the parallel light, it is assumed that a pinhole is arranged on the incident side of the photodetector. However, in this case, the traveling direction of light is refracted at the edge of the pinhole, and phenomena such as interference and diffraction are likely to occur. as a result,
Since there is a possibility of projecting interference fringe patterns with different phase information on the light receiving surface of the photodetector, the phase component of the light will not be constant, and it will be difficult to obtain an accurate birefringence. Was.

In order to reduce the beam diameter of the laser beam while keeping the beam diameter parallel and hardly suffering from disturbances such as light interference and diffraction phenomena as in a pinhole, a part of a light beam is cut using an optical fiber. We focused on the idea of extracting and transmitting light.

A birefringence measuring optical system according to the present invention has been completed based on the above-mentioned point of interest, and includes a light source side optical system for emitting an optical signal having a predetermined polarization state toward an object; A polarization detection optical system that detects an optical signal from the light source side optical system through the object as an optical signal capable of analyzing the birefringence of the object through polarization analysis, and an electric signal from the detection side optical system. A light detector that converts the light into a signal and detects the light, and extracts a part of the light beam of the optical signal from the object side to the light detector side between the light detector and the object to transmit the light. An optical transmission line, preferably an optical fiber, is provided.

In a preferred embodiment of the present invention, 1):
An optical fiber is disposed between a polarization detection optical system and a photodetector. 2): The optical fiber has a core made of a material having a predetermined photoelastic constant. 3): Polarization detection of the optical fiber with an object. 4): the optical fiber is provided with a tip sharpened toward the object side; 5): at least a part of the polarization detection optical system is integrally attached to the optical fiber; ): A mechanism for freely scanning at least the tip of the optical fiber on the object side within the light beam of the optical signal. 7): The optical fiber is a plurality of optical fibers.
At least one such as a case where the plurality of optical fibers are arranged in parallel is adopted.

Here, the type of the optical fiber is not particularly limited, and may be any of commercially available products having various core diameters. For example, if a plurality of optical fibers having different core diameters are arranged side by side, birefringence measurement can be performed simultaneously with different spatial resolutions. If an optical fiber having an opening diameter smaller than the core diameter of a commercially available product is required, an optical fiber having a narrower opening by sharpening the distal end portion by, for example, stretching the optical fiber may be used.

A high spatial resolution ellipsometer according to the present invention includes a birefringence measuring optical system using the above optical transmission line.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of a birefringence measuring optical system and a high spatial resolution ellipsometer according to the present invention will be described below with reference to the drawings.

(First Embodiment) The birefringence measuring optical system shown in FIG. 1 uses, for example, a birefringence measuring apparatus proposed in Japanese Patent Application Laid-Open No. 8-327498 to secure a wide dynamic range for measuring birefringence. Applied.

This measuring optical system uses a frequency stabilized transverse Zeeman laser (hereinafter referred to as “STZL (Stabi-lized Transverse Z)”.
eeman Laser) ”) The two-frequency orthogonal linearly polarized light generated in 10 is incident on the object OB via a λ / 2 wavelength plate (HWP) 20, and the transmitted light is subjected to the birefringence phase difference and principal axis direction of the object OB. The optical rotation angle information is detected by a photodetector 4 such as a photodiode via a linear polarizer (LP) 30 as an optical signal that can be subjected to polarization analysis. This optical system includes an optical fiber 5 between the linear polarizer 30 and the photodetector 4.
Is arranged.

Here, the principle of birefringence measurement using the optical fiber 5 will be described.

First, when the optical fiber 5 is not disposed, a portion corresponding to the entire region of the laser beam is directly incident on the photodetector 4 as shown in FIGS. Is a region B determined by the beam width of the laser light as shown in FIG. In this case, it is difficult to measure the birefringence distribution of a small area in the beam.

Next, when the optical fiber 5 is arranged, a part of the laser light from the linear polarizer 30 is extracted from the opening of the optical fiber 5 inserted and arranged in the laser beam as shown in FIG. Detected by the detector 4. The optical signal measured here is a part of a light beam extracted with a thickness substantially equal to the opening diameter of the optical fiber 5. For example, if the laser beam is parallel, the measurement area of the sample OB is It is equal to the opening diameter, and becomes a region A as shown in the figure.

Therefore, according to this embodiment, since the optical fiber 5 is arranged, the spatial resolution in the birefringence measurement is limited by using the aperture diameter, and only the light intensity of the optical signal extracted therefrom is increased. Can be propagated to the photodetector side with almost no disturbance such as diffraction or interference phenomenon. Although the optical fiber 5 also has a property of changing the polarization state, in the case of this optical system arrangement, the components to be considered in the polarization state in the birefringence measurement are STZL 10 in FIG. And because it is a linear polarizer 30, it can be almost ignored.

In this embodiment, since the birefringence information of the sample to be measured is included only in the change in the light intensity of the optical signal after passing through the linear polarizer, the optical fiber functions based on the birefringence measurement principle. Although it is arranged between the polarizing element closest to the photodetector and the photodetector, the present invention is not necessarily limited to this. Further, when it is particularly necessary in terms of the light condensing characteristics or when the light intensity is weak and the detection sensitivity does not increase, a lens system may be inserted between the optical fiber and the photodetector.

In this embodiment, the STZL, the λ / 2 wave plate, and the linear polarizer are employed as the birefringence measuring optical system in which the optical fiber is to be arranged, but the present invention is not necessarily limited to this. Absent.

For example, the birefringence measuring optical system shown in FIG. 5 is a high-level concept of the basic configuration based on the birefringence measuring principle of the present invention. In addition to the photodetector 4 and the optical fiber 5, a laser, a white light source, Light source unit 1 including a combination of a white light source and a spectroscope, a combination of a white light source and a wavelength selection filter, and light source side optics including all optical elements placed between the light source unit 1 and the sample OB The system includes a system 2 and a detection-side optical system 3 including all optical elements mounted between the sample OB and the photodetector 4. Here, the light source unit 1 and the light source side optical system 2 correspond to the polarized light emitting optical system of the present invention, and the detection side optical system 3 corresponds to the polarized light detection optical system of the present invention.

As a specific application example of the light source unit 1, the light source side optical system 2, and the detection side optical system 3, the above configuration (S
TZL10, λ / 2 wave plate 20, and linear polarizer 3
0), for example, any one of the following FIGS. 6 to 13 or a combination thereof.

The measuring optical system shown in FIG.
ZL10, a high-speed birefringence measurement method using a λ / 4 plate 21 for the light source side optical system 2 and a λ / 4 plate 31 and the linear polarizer 30 for the detection side optical system 3 (for example, Japanese Patent Application Laid-Open No. H8-25449).
No. 5).

The measuring optical system shown in FIG. 7 has a laser 11 in the light source 1 and a frequency shifter (linear polarizer,
A beam splitter, an acousto-optic element (AOM), a reflection mirror, etc.) 22 and a λ / 4 plate 21, a detection-side optical system 3
6 employs a λ / 4 plate 31 and a linear polarizer 30, respectively. Compared with the optical system shown in FIG.
The difference is that a frequency shifter 22 in which an acousto-optic element is combined and a normal laser 11 are used in place of 10.

The measuring optical system shown in FIG. 8 includes a laser 11 in the light source section 1, a linear polarizer 23 and a photoelastic modulator (PEM) 24 in the light source side optical system 2, and a linear polarizer 30 in the detection side optical system 3. Each is adopted. In this case, as shown in FIG. 9, a configuration in which a combination of a white light source 12 and a spectroscope 13 is employed in the light source unit 1 instead of the laser 11 may be employed.

The measuring optical system shown in FIG. 10 has a linear polarizer 23 in the light source side optical system 2 and a linear polarizer 30 in the detection side optical system 3.
For example, a rotating analyzer method or a rotating polarizer method is applied. As a modification of this case, when the phase shifter 32 is arranged between the sample OB and the linear polarizer 30 shown in FIG. 11, the phase shifter 25 is arranged between the sample OB and the linear polarizer 23 shown in FIG. When the same two phase shifters 25 and 32 are arranged (see FIG. 13)
Etc. can also be applied.

Although this embodiment employs an optical arrangement for measuring the transmitted light of the sample, the present invention is not limited to this. For example, as shown in FIG. The detection-side optical system 3, the optical fiber 4, and the photodetector 5 may be arranged at positions where light is measured. Such a configuration for measuring the reflected light is particularly effective for a sample that hardly transmits light.

(Second Embodiment) A high spatial resolution ellipsometer shown in FIG.
No. 8, the birefringence measuring device proposed in Japanese Patent Application Laid-open No. 8 is applied, and the birefringence measuring optical system (laser light source (ST
ZL10), λ / 2 wave plate 20, and linear polarizer 3
0), a motor driver 6 for rotationally driving the λ / 2 wavelength plate 20 and the linear polarizer 30, a lock-in amplifier 7 for signal processing, a computer 8 for data calculation, an XY stage 9 for mounting a sample, and STZL. Equipped with a laser controller 10a.

The ellipsometer includes a lock-in amplifier 7
The sine wave signal and the cosine wave signal of the AC component having the same frequency as the reference signal by the laser controller 10a are extracted from the detection signal by the photodetector 4 by the signal processing of the photodetector 4. The refraction phase difference, the principal axis azimuth, and the optical rotation angle are obtained.

Next, a verification experiment for confirming the effectiveness of the polarization analyzer using the optical fiber 5 was attempted. In this measurement experiment, a Babinet Soleil compensator (hereinafter, referred to as “BSC”), which is an optical element having a variable birefringence, is used as a sample OB, and any one of the birefringence of the BSC and the principal axis direction is set as a linear function. It is a result of examining the correlation between the measured value and the time when the value is changed.

FIG. 16 illustrates a case where the birefringence of the BSC is changed. In this case, the measured value changed linearly with respect to the set value of BSC, and it was confirmed that the correlation between them was high. Here, although the birefringence amount is turned back at 180 degrees, since it is measured that the principal axis direction is reversed, that is, the main axis direction is changed by 90 degrees, an almost physically correct value is obtained. Also in the case where the main axis direction of the BSC shown in FIG. 17 was changed, it was similarly confirmed that the set value of the BSC and the measured value showed a good correlation.

According to this measurement experiment, the birefringence measurement method with high spatial resolution using the optical fiber 5 is effective not only in principle but also in practice. For example, a laser beam irradiation spot on a sample surface is two-dimensionally scanned. By doing so, it was demonstrated that the birefringence distribution can also be measured with high spatial resolution.

Therefore, an experiment was conducted to examine the effectiveness of the high spatial resolution birefringence measurement. In this measurement experiment, an acrylic floppy disk case (hereinafter, referred to as an “FD case”) shown in FIG. 18 was used as the sample OB, and a protrusion formed on the inner edge of the case was used as a measurement part of the FD case. Notch was selected.

In such a notch, the birefringence in the polymer orientation changes sharply during molding. This was clearly confirmed as a change in color tone by an observation device using a sharp color plate method conventionally known as a simple birefringence observation method. According to this sensitive color plate method, a portion showing almost no birefringence is observed in red-violet, and a portion exhibiting birefringence is observed in a color whose hue has changed from red-violet. The birefringence was measured using the FD case notch showing such birefringence as a measurement location (see FIG. 18). For comparison, the same measurement was performed in the conventional example. FIGS. 19 and 20 show the results.
Shown in

FIG. 19 shows the case of the optical fiber detection method,
, Respectively, describe the case of the conventional example. Here, if the birefringence of the sample is large and the molecules are oriented in a twisted manner in the sample, not only birefringence but also optical rotation is generally exhibited. As a result, with respect to the measured values (birefringence phase difference, principal axis direction, and light application angle), the use of the optical fiber shown in FIG. It was confirmed that the state of refraction change was measured with finer accuracy. The same experiment was repeated several times, and in each case, the same tendency was shown.

In this embodiment, the method of scanning the sample with the XY stage is adopted, but the present invention is not limited to this, and a method of scanning an optical fiber in a beam may be used. In particular, when scanning a very small area, a relatively expensive scanning stage is required to precisely drive a large sample. Therefore, for example, a method of scanning the optical fiber 5 as shown in FIG. 21 is desirable. Secondly, there are also advantages such as miniaturization of the XY stage to further improve the positioning accuracy.

(Third Embodiment) In a general optical fiber,
Due to the internal stress caused by the curvature and the like, the polarization state changes when the optical signal passes through the optical fiber due to the photoelastic effect that accompanies it. It is substantially confined to the detector. In this embodiment, the selection of the arrangement position is expanded by devising the material of the optical fiber.

That is, the birefringence measuring optical system shown in FIG.
Since the optical fiber 5 is made of a material having a photoelastic constant of 0 or a material small enough not to have a significant effect on the polarization state, for example, a material having a core made of glass containing high lead content, the optical fiber 5 is connected to the sample OB and the detection side. It can be arranged between the optical system 3.

According to this embodiment, since the optical fiber can be arranged close to the sample, there is an advantage that the measurement position can be more accurately determined by observing the sample surface visually or by an optical microscope.

As yet another mode, the birefringence measuring optical system shown in FIG. 23 has a similar optical fiber 5 placed between the light source side optical system 2 and the sample OB. In this case, in addition to the above-mentioned effects, the mutual positional relationship between the optical element for birefringence measurement and the sample can be changed more flexibly, and as a result, for example, a vacuum device, a heat treatment device, an oil bath, etc. The birefringence measurement can be performed even in a state where the sample OB is set in the chamber 100, and there is an advantage that various characteristics such as temperature dependence of birefringence can be measured more easily.

(Fourth Embodiment) In general, if a light beam is focused on a sample using a lens, the spatial resolution on the sample surface is improved, but the light flux in the beam differs from the sample. Although an accurate birefringence amount cannot be obtained due to the incident angle, in this embodiment, even when such a converging lens is used, it has been devised that birefringence measurement using an optical fiber becomes possible. Things.

The birefringence measuring optical system shown in FIG. 24 has a focusing lens 60 between the light source side optical system 2 and the sample OB, and a collimator lens 61 between the sample OB and the detection side optical system 3.
The collimator lens 61 converts the light beam that has passed through the sample into parallel light, and the optical fiber 5 placed on the optical axis selects and extracts only the speed of light that travels straight through the sample OB. ing.

According to this embodiment, since the light beam can be irradiated only to a limited area on the sample, especially when the sample has a structure such as a refractive index and causes light diffraction or the like. It is valid. This is because, if the parallel light is incident on the sample, the light beam is also irradiated to a region outside the measurement range, and the diffracted light from the irradiated region may enter the optical fiber as a signal noise source. That is, if a small irradiation spot of the light beam is formed on the sample, there is an effect of preventing measurement of an extra light signal from a region outside the measurement range. Further, by forming a light spot on the sample, there is an advantage that the measurement position can be more easily observed.

The birefringence measuring optical system shown in FIG. 25 uses only the converging lens 60 except for the collimator lens described above. However, the central part of the spread of the optical signal from the sample OB, that is, on the optical axis Only the luminous flux travels straight, and therefore, a minute area on the optical axis can be regarded as parallel light. Therefore, in this case, the same effect as described above can be obtained.

(Fifth Embodiment) The birefringence measuring optical system shown in FIG. 26 has a function of expanding the beam width of incident light between the light source unit 1 and the light source side optical system 2 and emitting the light as a parallel light beam. Is arranged, and the optical fiber 5 is two-dimensionally scanned by the XY stage 9 to obtain a two-dimensional distribution of birefringence of the sample OB.

Using this beam expander 70,
There is an advantage that the irradiation area of the light on the sample surface can be made larger and the area that can be measured by one scan can be widened.

In this embodiment, the beam expander is arranged between the light source unit and the light source side optical system. However, the present invention is not limited to this. For example, as shown in FIG. The same effect can be obtained even if it is arranged between the side optical system 2 and the sample OB.

(Sixth Embodiment) In this embodiment, a scanning tunneling microscope (STM), which is under research and development in recent years as a microscope exceeding the diffraction limit of light, is used as an optical fiber for the above-described birefringence measurement. Among the typical scanning probe microscopes (SPMs), those employed as scanning probes for near-field optical microscopes are applied.

That is, as shown in the figure, the double cylindrical optical fiber 5 having the core 51 and the clad 52 covering the core 51 shown in FIGS. The tip is sharpened by using a manufacturing method such as a melt drawing method in which it is pulled from both sides. If such an optical fiber 5 is used, the aperture can be made smaller than the original size, and there is an advantage that the spatial resolution in birefringence measurement is further enhanced.

(Seventh Embodiment) The optical fiber 5 shown in FIG. 29 may be a polymer thin film such as a polarizer or a retarder, a vapor-deposited film (including a multilayer film (synthetic film) of the retarder and the polarizer) or a film after the vapor deposition. The detection-side optical system 3 composed of an optical element manufactured by using the coloring method or the like is integrally adhered to the opening by vapor deposition or sputtering.

According to this embodiment, since the optical fiber and the detection-side optical system (polarizing element) are integrated,
Even if a special optical fiber having a photoelastic constant close to 0 is not used, the optical fiber can be arranged at a position close to the sample with a relatively simple configuration, and the same effect as in the third embodiment can be obtained.

When it is necessary to rotate the polarizer or the like of the optical system on the detection side on the basis of the birefringence principle, a configuration for rotating the optical fiber itself about the optical axis may be added.

In this embodiment, the detection-side optical system is integrally attached to the optical fiber. In addition, for example, in the case of the optical system shown in FIG. Is also possible.

(Eighth Embodiment) The ellipsometer shown in FIG. 30 uses a plurality of optical fibers 5 on the exit side of the detection-side optical system 3.
a ... 5a are arranged in parallel, and each of these optical fibers 5a ... 5a
4a are individually assigned to the output side of a, and while the photocurrent signals detected by the plurality of photodetectors 4a... 4a are switched by the exchanger 41, one lock-in amplifier 7 and A (not shown) The signal is processed by a signal processing device such as a / D converter.

In this embodiment, the channel is switched by using an exchange. However, the present invention is not limited to this. For example, as shown in FIG. The configuration may be such that the amplifiers 7a to 7a are individually connected to perform parallel processing.

The aperture diameter of the optical fibers is not limited to the same one. For example, if optical fibers having different aperture diameters are used, there is an advantage that birefringence can be measured simultaneously with a plurality of spatial resolutions. The arrangement of the optical fibers may be one-dimensional or two-dimensional.

The first to eighth embodiments are not limited to independent configurations, and may be appropriately combined within the scope of the present invention.

[0065]

As described above, according to the present invention, microscopic measurement of the birefringence and in-plane distribution characteristics of a sample is performed quantitatively, not qualitatively using a conventional polarizing microscope. it can. In particular, compared to the conventional example in which convergent light is transmitted through a sample using a lens and all of the transmitted light is detected, parallel light is allowed to pass as it is, or only a portion that can be regarded as parallel light is represented by an optical fiber. Since the structure can be selected and extracted through the optical transmission line, the advantage is that the effect of oblique incidence birefringence on the sample can be avoided beforehand, and the amount of birefringence can be measured more accurately, while enhancing the spatial resolution. is there.

Therefore, the optical system and apparatus according to the present invention can observe the state of the birefringence distribution near the pits of the optical disk, the operation state of each pixel of the liquid crystal display, the state of the optical waveguide formed in the optical crystal, and the like. It can be widely used for research and development, quality evaluation and management.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing the overall configuration of a birefringence measurement optical system according to a first embodiment of the present invention.

FIG. 2 is a conceptual diagram of a conventional birefringence measuring optical system for explaining the principle of birefringence measurement.

FIG. 3 is a conceptual diagram illustrating a spatial resolution in the case of a conventional example.

FIG. 4 is a conceptual diagram illustrating spatial resolution when an optical fiber is used.

FIG. 5 is a schematic diagram of a birefringence measuring optical system that has been conceptualized as a generic concept.

FIG. 6 is a conceptual diagram of a birefringence measuring optical system when a λ / 4 plate or the like is used.

FIG. 7 is a conceptual diagram of a birefringence measuring optical system when a frequency shifter or the like is used.

FIG. 8 is a conceptual diagram of a birefringence measurement optical system when a photoelastic modulation element or the like is used.

FIG. 9 is a conceptual diagram of a birefringence measurement optical system when a white light source or the like is used.

FIG. 10 is a conceptual diagram of a birefringence measurement optical system when linear polarizers are used on both sides.

FIG. 11 is a conceptual diagram of a birefringence measurement optical system when a phaser is used on the detection side.

FIG. 12 is a conceptual diagram of a birefringence measurement optical system when a phase shifter is used on the light source side.

FIG. 13 is a conceptual diagram of a birefringence measurement optical system when a retarder is used on both sides.

FIG. 14 is a conceptual diagram of a birefringence measurement optical system when detecting reflected light.

FIG. 15 is a conceptual diagram showing the entire configuration of a high spatial resolution ellipsometer according to a second embodiment of the present invention.

FIG. 16 is a graph illustrating experimental results when the birefringence of BSC is changed.

FIG. 17 is a graph illustrating an experimental result when the main axis direction of the BSC is changed.

FIG. 18 is a schematic diagram of an FD case used in a verification experiment.

FIG. 19 is a graph illustrating experimental results in the case of the present invention using an optical fiber.

FIG. 20 is a graph illustrating an experimental result in the case of a conventional example.

FIG. 21 is a conceptual diagram illustrating a main part of an optical system when scanning an optical fiber.

FIG. 22 is a conceptual diagram of a birefringence measurement optical system when an optical fiber is arranged between a sample and a detection-side optical system.

FIG. 23 is a conceptual diagram of a birefringence measurement optical system when an optical fiber is also arranged between a sample and a light source side optical system.

FIG. 24 is a conceptual diagram of a birefringence measuring optical system when a focusing lens is used.

FIG. 25 is a conceptual diagram of another birefringence measuring optical system when a focusing lens is used.

FIG. 26 is a conceptual diagram of a birefringence measurement optical system when a beam expander is used.

FIG. 27 is a conceptual diagram when an arrangement position of a beam expander is changed.

FIGS. 28A and 28B are explanatory views of an optical fiber having a sharpened end.

FIG. 29 is an explanatory diagram of an optical fiber in which a detection-side optical system is integrally attached.

FIG. 30 is a conceptual diagram of a high spatial polarization analyzer when a plurality of optical fibers are used.

FIG. 31 is a conceptual diagram of another high spatial polarization analyzer when a plurality of optical fibers are used.

32A and 32B are diagrams illustrating a state of change in birefringence due to a difference in incident angle in a conventional example, and FIG. 32A is a conceptual diagram in the case of normal incidence. (B) and (c) are conceptual diagrams in the case of oblique incidence.

FIG. 33 is a conceptual diagram illustrating a case where convergent light is incident on a sample of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 light source unit 2 light source side optical system 3 detection side optical system 4, 4a photodetector 5, 5a optical fiber 6 motor driver 7, 7a lock-in amplifier 8 computer 9 XY stage 10 frequency stabilized lateral Zeeman laser (STZL) 10a Laser Controller 20 λ / 2 Wavelength Plate (HWP) 30 Linear Polarizer (LP) 41 Exchanger 51 Core 52 Clad 60 Focusing Lens 61 Collimator Lens 70 Beam Expander

Claims (10)

[Claims] 1. A polarized light emitting optical system for emitting an optical signal having a predetermined polarization state toward an object, and an optical signal from the polarized light emitting optical system is transmitted through the object to obtain birefringence information of the object. A polarization detection optical system that detects the light as an optical signal that can be analyzed for polarization, and a light detector that converts the light signal from the polarization detection optical system into an electric signal and detects the light signal. A birefringence measuring optical system, wherein an optical transmission path for extracting a part of the light beam of the optical signal from the object side to the photodetector side and transmitting the light is disposed. 2. The birefringence measuring optical system according to claim 1, wherein said optical transmission path is constituted by an optical fiber. 3. The birefringence measuring optical system according to claim 2, wherein said optical fiber is disposed between said polarization detecting optical system and said photodetector. 4. The birefringence measurement optical system according to claim 2, wherein said optical fiber has a core made of a material having a predetermined photoelastic constant. 5. The birefringence measuring optical system according to claim 4, wherein said optical fiber is disposed between said object and said polarization detecting optical system. 6. The birefringence measuring optical system according to claim 2, wherein the optical fiber has a tip portion sharpened toward the object side. 7. The birefringence measuring optical system according to claim 2, wherein at least a part of said polarization detecting optical system is integrally attached to said optical fiber. 8. The birefringence measurement optical system according to claim 2, further comprising a mechanism for freely scanning at least a tip portion of the optical fiber on the object side within the light flux of the optical signal. 9. The birefringence measuring optical system according to claim 2, wherein the optical fiber is a plurality of optical fibers, and the plurality of optical fibers are arranged in parallel. 10. A high spatial resolution ellipsometer comprising the birefringence measuring optical system according to claim 1. Description: