Sample measurement device

Abstract

Provided is a sample measurement device that can achieve a simple and compact device configuration and measure the physical characteristics of a target sample by detecting the polarization state of light. 【Solution means】The sample measurement device A includes a light source 1, an unpolarized beam splitter 2, a polarization control type liquid crystal 3, and a polarization camera 4. Further, the sample measurement device A includes a linear polarizer 6 and an objective lens 7. Further, the polarization camera 4 detects a horizontally linearly polarized component and a vertically linearly polarized component of light that is light from the light source 1 and is derived from reflected light reflected by the target sample 5.

Description

Technical Field

[0001] The present invention relates to a sample measurement device.

Background Art

[0002] Conventionally, various methods have been used to nondestructively examine the properties of a substance by irradiating a target sample to be measured with light and measuring or analyzing the information of the reflected light.

[0003] For example, a device has been proposed that measures the physical characteristics of a target sample by detecting the traveling direction distribution of incident light in the target sample to be measured (see, for example, Patent Document 1).

[0004] In the sample measurement device described in Patent Document 1, by performing spatial polarization filtering on both the incident light and the reflected light, the inclination, undulation, minute steps, scratches, etc. of the reflection surface in the measurement target sample are detected.

[0005] Further, in the sample measurement device described in Patent Document 1, the light irradiated on the target sample is passed through a polarization beam splitter that selectively extracts polarization components in specific directions (the polarization component in the x-axis direction and the polarization component in the y-axis direction), and then the respective polarization components are detected by two polarization cameras.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the sample measurement device described in Patent Document 1, in order to detect the polarization component in the x-axis direction and the polarization component in the y-axis direction, as described above, it is necessary to combine a polarization beam splitter and two cameras, and there has been a problem that the device configuration becomes complicated and large-sized.

[0008] In addition, since it is necessary to perform calibration (such as pixel misalignment and field-of-view correction) for each of the two cameras, it takes time to adjust the entire system, and there is a risk that the measurement accuracy will be low.

[0009] In addition, the sample measurement device described in Patent Document 1 had room for improvement in that it highly sensitively detected light with low intensity scattered by minute steps on the surface or the like from among the reflected light reflected by the target sample.

[0010] Furthermore, the sample measurement device described in Patent Document 1 is a device that acquires only information on the intensities of the polarization components in the x-axis direction and the y-axis direction for the reflected light from the target sample, and there was also room for improvement in that it was configured to obtain more detailed information on the polarization state in order to examine the detailed characteristics of the substance.

[0011] The present invention was devised in view of the above points, and an object thereof is to provide a sample measurement device capable of realizing a simple and compact device configuration and measuring the physical characteristics of a target sample by detecting the polarization state of light.

Means for Solving the Problems

[0012] To achieve the above object, the sample measurement apparatus of the present invention includes a light source, light from the light source that receives reflected light reflected from a target sample, and detects a horizontal linearly polarized light component and a vertical linearly polarized light component derived from the reflected light, a polarization camera, a predetermined optical element that can branch light at a specific ratio while maintaining the polarization state, guides a part of the light emitted from the light source to the target sample, and guides a part of the reflected light to the polarization camera, and a polarization conversion element disposed between the target sample and the predetermined optical element and having a plurality of sections capable of individually controlling the polarization of the transmitted light. The polarization conversion element is configured to transmit, while maintaining the polarization state of the light, the light among the reflected light that has a deviation in the optical path from the incident light to the target sample, and to be able to convert the polarization state of the light to another polarization state and transmit it according to the amount of deviation in the optical path.

[0013] Here, the light from the light source can be irradiated onto the surface of the target sample by the light source and a predetermined optical element that can branch light at a specific ratio and guide a part of the light emitted from the light source to the target sample.

[0014] Further, since the predetermined optical element can branch light at a specific ratio while maintaining the polarization state and guides a part of the reflected light reflected from the target sample to the polarization camera, the light reflected by the target sample from the light source can be guided to the polarization camera without changing the polarization state of the light before and after passing through the predetermined optical element.

[0015] In addition, since the polarization conversion element is disposed between the target sample and the predetermined optical element and has a plurality of sections capable of individually controlling the polarization of the transmitted light, the polarization of the light can be changed for each section, and the polarization state of a specific polarization can be detected by the polarization camera. Along with this, when the reflected light reflected by the target sample includes strongly specularly reflected light and weakly scattered light due to minute steps on the surface, etc., the polarization can be controlled to highly sensitively detect even weak light.

[0016] In addition, when the polarization camera receives the reflected light that is the light from the light source and reflected from the target sample, and detects the horizontal linearly polarized light component and the vertical linearly polarized light component derived from the reflected light, the surface state of the target sample can be visualized based on the linearly polarized light components in two directions. That is, by acquiring the intensity distribution images of the linearly polarized light components in two directions, it is possible to confirm the presence or absence of minute steps or inclinations on the surface of the target sample. Also, since information on the linearly polarized light components in two directions can be obtained with a single polarization camera, it becomes easier to miniaturize the entire device. Further, compared with the mode using two cameras, the labor of operations such as calibration of the polarization camera is reduced, and the adjustment of the device can be facilitated.

[0017] In addition, for the light among the reflected light in which a deviation in the optical path occurs between the incident light to the target sample, the polarization conversion element can transmit the light while maintaining its polarization state, and can convert the polarization state of the light to another polarization state according to the amount of deviation in the optical path and then transmit it. By this, it is possible to detect the scattering component caused by the unevenness or the like on the surface of the target sample. That is, when light scattering occurs on the surface of the target sample irradiated with light due to unevenness or the like, a deviation in the optical path occurs between the incident light and the reflected light. By comparing the image captured by the polarization camera after converting the polarization state of the reflected light to another polarization state according to the amount of deviation in the optical path by the polarization conversion element and the image captured by the polarization camera while maintaining the polarization state of the reflected light, it becomes possible to detect the light scattering component.

[0018] In addition, when the polarization camera detects the 45° linearly polarized light component and the 135° linearly polarized light component derived from the reflected light, information on the linearly polarized light components in four directions can be obtained, including the horizontal linearly polarized light component and the vertical linearly polarized light component. That is, by combining and analyzing the intensities of the linearly polarized light components in four directions, it is possible to confirm the type of polarization, whether it is linearly polarized light, circularly polarized light, or elliptically polarized light, regarding the polarization state of the reflected light from the surface of the target sample.

[0019] Also, when a phase plate that is detachably installed between a polarization camera and a predetermined optical element and imparts a predetermined phase difference to the light guided from the predetermined optical element to the polarization camera is provided, for the light reflected from the surface of the target sample and traveling from the predetermined optical element toward the polarization camera, an image of the light with the phase difference imparted and an image of the light without the phase difference imparted can be captured by the polarization camera. More specifically, the phase plate can change the state of incident polarized light by imparting a phase difference to two orthogonal polarization components of the passing light. Then, based on the information on the amount of the phase difference imparted by the phase plate and the information obtained by comparing the changes in the linear polarization components in four directions with and without the phase difference, it becomes possible to confirm the direction of rotation (clockwise or counterclockwise) of circular polarization regarding the polarization state of the reflected light. Also, even when the material constituting the target sample has optical anisotropy and the change in the polarization state of the reflected light varies depending on the difference in the incident angle of the incident light, by comparing the changes in the linear polarization components in four directions with and without the phase difference, it is possible to capture the change in the polarization state caused by the material.

[0020] Also, when an electrically controllable birefringence variable polarization element that is installed between a polarization camera and a predetermined optical element and can impart a predetermined phase difference to the light guided from the predetermined optical element to the polarization camera by electrical control is provided, for the light reflected from the surface of the target sample and traveling from the predetermined optical element toward the polarization camera, an image of the light with the phase difference imparted and an image of the light without the phase difference imparted can be captured by the polarization camera. More specifically, the electrically controllable birefringence variable polarization element can change the state of incident polarized light by imparting a phase difference to two orthogonal polarization components of the passing light. Then, based on the information on the amount of the phase difference imparted by the electrically controllable birefringence variable polarization element and the information obtained by comparing the changes in the linear polarization components in four directions with and without the phase difference, it becomes possible to confirm even the information on the direction of rotation of circular polarization regarding the polarization state of the reflected light. Also, even when the material constituting the target sample has optical anisotropy and the change in the polarization state of the reflected light varies depending on the difference in the incident angle of the incident light, by comparing the changes in the linear polarization components in four directions with and without the phase difference, it is possible to capture the change in the polarization state caused by the material.

[0021] In addition, when the Stokes parameters of the target sample can be obtained based on the information on the polarization components detected by the polarization camera, the polarization state of the reflected light from the surface of the target sample can be specified as the information on the physical quantity representing the physical properties of polarization.

[0022] In addition, when the predetermined optical element is an unpolarized beam splitter, the light irradiated from the light source to the target sample and the reflected light returning from the target sample can be handled on the same optical axis. As a result, the optical system becomes simple, the adjustment of the apparatus becomes easy, and the cost for manufacturing can be suppressed.

Advantages of the Invention

[0023] The sample measurement apparatus according to the present invention can realize a simple and small-sized apparatus configuration, and can measure the physical characteristics of a target sample by detecting the polarization state of light.

Brief Description of the Drawings

[0024]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0025] Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as "embodiments") will be described with reference to the drawings. Note that the content shown below is an explanation of an example of a sample measurement apparatus to which the present invention is applied, and the content of the present invention is not limited thereto, and design changes can be made as appropriate.

[0026] [First Embodiment of the Present Invention] As shown in FIG. 1, the sample measurement apparatus A includes a light source 1, an unpolarized beam splitter 2, a polarization control type liquid crystal 3, and a polarization camera 4.

[0027] This sample measurement device A irradiates the light from the light source 1 onto the target sample 5 (see Fig. 1), captures the reflected light reflected from the surface of the target sample 5 with the polarization camera 4, and measures the polarization state of the reflected light.

[0028] In addition, the sample measurement device A has a linear polarizing plate 6 and an objective lens 7 (see Fig. 1).

[0029] Here, the light source 1 is a member for emitting light to irradiate the target sample 5. For example, an LED light source can be adopted.

[0030] In addition, the unpolarized beam splitter 2 is an optical element that guides a part of the light irradiated from the light source 1 to the target sample 5. The unpolarized beam splitter 2 is also a member that guides a part of the reflected light reflected from the surface of the target sample to the polarization camera 4.

[0031] Note that the unpolarized beam splitter 2 here is a member corresponding to a predetermined optical element in the claims of this application.

[0032] In addition, the unpolarized beam splitter 2 is an optical element that branches light at a certain ratio while maintaining the polarization state of the incident light. That is, for example, the light incident on the unpolarized beam splitter 2 is partially reflected toward the target sample 5, and the remaining part passes through the unpolarized beam splitter 2 and is branched at a certain ratio.

[0033] In addition, the polarization control type liquid crystal 3 is a liquid crystal element composed of a plurality of sections, and controls polarization for each section. These plurality of sections are, for example, arranged in a planar and lattice-like shape.

[0034] In addition, the polarization control type liquid crystal 3 is a member that can convert the polarization state of the reflected light to another polarization state for each section according to the amount of the optical path shift of the light that has an optical path shift between the incident light and the reflected light to the target sample and can transmit it. The details of this part will be described later.

[0035] Note that the polarization control type liquid crystal 3 mentioned here is a member corresponding to the polarization conversion element in the claims of the present application.

[0036] Also, the linear polarizing plate 6 is a polarizing plate that converts the light from the light source 1 into linearly polarized light vibrating in only one direction (for example, linearly polarized light vibrating only in the y-axis direction).

[0037] Also, the objective lens 7 is a lens member that passes through the polarization control type liquid crystal 3 and condenses the light heading toward the target sample 5. Further, the objective lens 7 is also a lens member that condenses the reflected light reflected by the target sample 5 and directs it toward the polarization camera 4 side.

[0038] Also, the polarization camera 4 is a camera that detects the horizontally linearly polarized light component (linearly polarized light component vibrating only in the x-direction) and the vertically linearly polarized light component (linearly polarized light component vibrating only in the y-direction) of the light that is the light from the light source 1 and is derived from the reflected light reflected by the target sample 5.

[0039] With this polarization camera 4, it is possible to acquire intensity distribution images of the linearly polarized light components in two directions, the horizontal direction and the vertical direction.

[0040] Also, in the sample measurement device A, in the light propagation path, the unpolarized beam splitter 2 is disposed between the light source 1 and the polarization control type liquid crystal 3 and also between the polarization control type liquid crystal 3 and the polarization camera 4.

[0041] Due to the arrangement position of such an unpolarized beam splitter 2, in the sample measurement device A, it is possible to handle the light irradiated to the target sample and the reflected light reflected from the surface of the target sample on the same optical axis.

[0042] Also, in the sample measurement device A, the polarization control type liquid crystal 3 is disposed between the unpolarized beam splitter 2 and the objective lens 7.

[0043] Also, in the sample measurement device A, the light source 1, the unpolarized beam splitter 2, and the polarization control type liquid crystal 3 are all disposed on one surface side (the reflection surface side) of the target sample 5.

[0044] Here, it is not necessarily required to use the non-polarizing beam splitter 4 in the sample measurement apparatus A. Any optical element capable of splitting light at a certain ratio while maintaining the polarization state may be used. For example, a half mirror can also be used. However, the light emitted from the light source 1 and the reflected light from the target sample 5 can be handled on the same optical axis, which simplifies the optical system and makes the adjustment of the apparatus easier. Also, from the perspective that the polarization dependence on the transmittance and reflectance is small for each type of polarization and the correction of the polarization characteristics is easy, it is preferable to use the non-polarizing beam splitter 4 in the sample measurement apparatus A.

[0045] Next, the light propagation path in the sample measurement apparatus A will be described. First, the light emitted from the light source 1 passes through the linear polarizer 6 and becomes linearly polarized light vibrating only in the y-axis direction by the linear polarizer 6.

[0046] Also, the light that has passed through the linear polarizer 6 reaches the non-polarizing beam splitter 2, and a part of it is reflected toward the polarization control type liquid crystal 3, and this light passes through the polarization control type liquid crystal 3 in a linearly polarized state. At this time, the section through which the light passes in the polarization control type liquid crystal 3 is controlled in a setting that maintains the polarization state.

[0047] Also, the light that has passed through the polarization control type liquid crystal 3 is condensed by the objective lens 7 and irradiated onto the surface of the target sample. Also, on the surface of the target sample, the irradiated light is reflected, the reflected light is condensed by the objective lens 7, and passes through the polarization control type liquid crystal 3 again.

[0048] Also, in the polarization control type liquid crystal 3, the polarization of the reflected light from the target sample can be changed for each section to transmit the light. In the polarization control type liquid crystal 3, which section among the plurality of sections the light passes through will vary depending on the way of reflection (such as the presence or absence of scattering) on the surface of the target sample.

[0049] Here, the reflected light includes specularly reflected light that has no deviation in the optical path in relation to the incident light, and reflected light that has undergone scattering due to unevenness on the surface of the target sample, resulting in a deviation in the optical path. Usually, in the reflected light, specularly reflected light occupies most of it, and the proportion of scattered light is small.

[0050] Therefore, in the polarization control type liquid crystal 3, in the section where specularly reflected light passes, by controlling the polarization, when the reflected light is imaged by the polarization camera 4, the detection amount of strongly specularly reflected light with high intensity can be suppressed, and weakly scattered reflected light with low intensity can be detected with high sensitivity. More specifically, by converting specularly reflected light into a specific polarization, the detection amount of a specific polarization component of the polarization camera becomes small, resulting in a phenomenon of entering the dark field mode. As a result, weak light (a small component) can be visualized.

[0051] Also, in the polarization control type liquid crystal 3, for the reflected light from the target sample, the polarization state of the reflected light can be adjusted in two ways: one is to let the reflected light pass through each section while maintaining the polarization state, and the other is to convert the polarization state of the reflected light to another polarization state according to the amount of deviation in the optical path and let it pass through the section where the reflected light with a deviation in the optical path passes.

[0052] Here, converting the polarization state of the reflected light to another polarization state according to the amount of deviation in the optical path in the section where the reflected light with a deviation in the optical path passes is, for example, the following conversion.

[0053] In section a where reflected light with a certain amount of deviation in the optical path passes, linearly polarized light vibrating only in the y-axis direction is rotated by 90 degrees and converted into linearly polarized light vibrating only in the x-axis direction, and then passes through section a.

[0054] Also, in section b where reflected light with another amount of deviation in the optical path passes, linearly polarized light vibrating only in the y-axis direction is rotated by 45 degrees and converted into linearly polarized light having vibration components in both the x-axis direction and the y-axis direction, and then passes through section b.

[0055] Furthermore, in section c through which the specularly reflected light without optical path deviation passes, linearly polarized light vibrating only in the y-axis direction is allowed to pass as linearly polarized light vibrating only in the y-axis direction without being optically rotated.

[0056] In this way, in the polarization control type liquid crystal 3, depending on the amount of optical path deviation, the section through which the reflected light passes is different, and it is possible to convert the light into different polarization states for each section.

[0057] Then, the reflected light that has passed through the polarization control type liquid crystal 3 is incident on the non-polarizing beam splitter 2, and while maintaining its polarization state, it is branched at a certain ratio, passes through the non-polarizing beam splitter 2, and is incident on the polarization camera 4.

[0058] Also, depending on whether or not the polarization state of the light is converted according to the amount of optical path deviation by the above-described polarization control type liquid crystal 3, the polarization camera 4 can obtain a detection result in a state where two detections, namely, the detection of the reflected light whose polarization state is maintained in each section of the polarization control type liquid crystal 3 and the detection of the reflected light converted into different polarization states depending on the section, are mixed.

[0059] By confirming the detection result in which these two detections obtained by the polarization camera 4 are mixed, it becomes possible to capture the scattering caused by the unevenness or the like on the surface of the target sample as a difference in polarization state. That is, in the sample measuring device A, it is possible to separate the scattering component caused by the unevenness or the like on the surface of the target sample.

[0060] In this way, in the sample measuring device A, by detecting the linearly polarized light components in the horizontal and vertical directions with the polarization camera 4, it is possible to accurately detect minute unevenness, steps, scratches, inclination of the reflecting surface, undulations, etc. on the surface of the target sample.

[0061] Also, in the sample measuring device A, since the device can be constructed by combining the non-polarizing beam splitter 2 and one polarization camera 4, the device configuration is relatively simple, and the entire device can be miniaturized.

[0062] [Second Embodiment of the Present Invention] Next, a second embodiment of the present invention will be described. A sample measuring apparatus B according to the second embodiment of the present invention is shown in FIG. 2. Note that the same members as those in the first embodiment of the present invention described above are denoted by the same reference numerals and the description thereof is omitted.

[0063] As shown in FIG. 2, the sample measuring apparatus B has a polarization camera 40.

[0064] This polarization camera 40 is a camera that detects a horizontally linearly polarized component, a vertically linearly polarized component, a 45° linearly polarized component, and a 135° linearly polarized component of light that is light from the light source 1 and is derived from the reflected light reflected by the target sample 5.

[0065] With this polarization camera 40, intensity distribution images of linearly polarized components in four directions, namely, the horizontal direction, the vertical direction, the 45° direction, and the 135° direction, can be acquired.

[0066] According to this, in the sample measuring apparatus B, regarding the polarization state of the reflected light from the target sample, based on the intensities of the linearly polarized components in four directions, it is possible to specify which of linearly polarized light, circularly polarized light, or elliptically polarized light the polarization type corresponds to.

[0067] In the sample measuring apparatus B, information on the type of polarization that could not be confirmed only with information on the two linearly polarized components by the horizontally and vertically linearly polarized components can be acquired, and a more detailed polarization state of the reflected light can be grasped.

[0068] [Third Embodiment of the Present Invention] Next, a third embodiment of the present invention will be described. A sample measuring apparatus C according to the third embodiment of the present invention is shown in FIG. 3. Note that the same members as those in the first embodiment and the second embodiment of the present invention described above are denoted by the same reference numerals and the description thereof is omitted.

[0069] As shown in FIG. 3, the sample measurement device C has a λ / 4 plate 8. This λ / 4 plate 8 is an element that gives a phase difference of λ / 4 (90°) to one of two orthogonal polarization components that make up the polarization of the light transmitted through the unpolarizing beam splitter 2, and changes the state of the incident polarization. Here, the λ / 4 plate 8 mentioned here is a member corresponding to the phase element in the claims of the present application.

[0070] For example, if the light incident from the unpolarizing beam splitter 2 to the λ / 4 plate 8 is linearly polarized at 45°, the light passing through the λ / 4 plate 8 is given a phase difference of λ / 4 (90°) and is converted into circularly polarized light.

[0071] The sample measurement device C also has a polarization camera 40. In the sample measurement device C, the λ / 4 plate 8 is detachably installed.

[0072] According to the attachment and detachment of this λ / 4 plate 8, the polarization states of the light that does not pass through the λ / 4 plate 8 (in the state where the λ / 4 plate 8 is removed) and the light that passes through the λ / 4 plate 8 (in the state where the λ / 4 plate 8 is installed) can be acquired by the polarization camera 40.

[0073] That is, in the sample measurement device C, by attaching and detaching the λ / 4 plate 8 and imaging the reflected light from the target sample with the polarization camera 40, eight types of intensity distribution images can be obtained, which are the linearly polarized components in four directions (horizontal direction, vertical direction, 45° direction, and 135° direction) and the pattern of the presence or absence of a phase difference.

[0074] That is, regarding the polarization state of the reflected light from the target sample, by being able to acquire information on the change in the amplitude of the polarization component and the change in the phase, in addition to the information on the type of polarization, it becomes possible to confirm even the direction of rotation (clockwise or counterclockwise) of the circularly polarized light regarding the polarization state of the reflected light.

[0075] Here, by obtaining the intensity distribution of the linearly polarized components in four directions (horizontal direction, vertical direction, 45° direction, and 135°), the type of polarization, and the information on the direction of rotation of the circularly polarized light, all the information necessary to specify the state of the electromagnetic wave of the light has been obtained.

[0076] As a result, in the sample measurement device C, it becomes possible to separate the polarization characteristics of the target sample 5 composed of a material having optical anisotropy (showing birefringence).

[0077] That is, when the material constituting the target sample 5 is composed of a material having optical anisotropy, the polarization state of the reflected light changes depending on the difference in the incident angle of the light incident on the surface of the target sample 5. For the reflected light of the incident light at a certain incident angle, the polarization state does not change, but for the reflected light of the incident light at another incident angle, it is reflected in a polarization state different from the polarization state of the incident light.

[0078] Regarding the change in the polarization state caused by the optical anisotropy of the material constituting such a target sample 5, in the sample measurement device C, it can be grasped by comparing the changes in the four-direction linear polarization components with and without the λ / 4 plate 8.

[0079] Also, by using the sample measurement device C to obtain information on the changes in the four-direction linear polarization components with and without the λ / 4 plate 8, it becomes possible to calculate the Stokes parameters, which are physical quantities representing the physical properties of polarization.

[0080] The Stokes parameters S0, S1, S2, and S3 are generally defined as follows: S0 is the total light intensity, S1 is the difference in the light intensities of the 0° linear polarization component and the 90° linear polarization component, S2 is the difference in the light intensities of the 45° linear polarization component and the 135° linear polarization component, and S3 is the difference in the light intensities of the right-handed circular polarization component and the left-handed circular polarization component.

[0081] In this way, in the sample measurement device C, it becomes possible to represent the polarization state of the reflected light from the target sample as Stokes parameters.

[0082] Here, it is not always necessary for the λ / 4 plate 8 to be detachably installed in the sample measurement device C. Instead of the λ / 4 plate 8, an electrically controlled birefringence variable polarization element can also be used. For example, an electrically controlled birefringence type liquid crystal, which is an example of an electrically controlled birefringence variable polarization element, utilizes the birefringence of the liquid crystal and can change the phase difference by applying a voltage to the liquid crystal molecules, thereby imparting a phase difference to the passing light.

[0083] Also, in the sample measurement device C, it is not necessarily required that the quarter-wave plate 8 be detachably installed, and a wave plate with a different amount of phase difference imparted to light can be adopted. For example, a half-wave plate can be used. Further, it is only necessary to be able to measure a plurality of polarization states based on the presence or absence of a phase difference, and if the amount of phase difference to be imparted is clear, it is also possible to adopt a wave plate other than a quarter-wave plate or a half-wave plate.

[0084] Thus, in the sample measurement device C according to the third embodiment of the present invention, regarding the polarization state of the reflected light from the target sample 5, information on the intensity distribution of the linearly polarized light components in four directions, the type of polarization, and the direction of rotation of the circular polarization can be obtained, and the detailed polarization state of the reflected light can be confirmed.

[0085] The sample measurement device according to the first to third embodiments of the present invention is useful, for example, as a technique for quickly detecting minute steps and film unevenness on the surface of a semiconductor wafer, a glass substrate, or the like.

[0086] Also, it is possible to visualize or quantify extremely small scratches and defects on the surface of components of a smartphone terminal, optical devices, or the like.

[0087] Also, it is possible to detect unevenness on the nano- to sub-micron order that was difficult to detect with conventional simple illumination and observation methods.

[0088] As described above, the sample measurement device of the present invention can achieve a simple and small device configuration, and can measure the physical characteristics of a target sample by detecting the polarization state of light.

[0089] Although the invention made by the present inventor has been specifically described based on the embodiments, it goes without saying that the present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist thereof.

Explanation of Reference Numerals

[0090] A sample measurement device 1 Light source 2 Non-polarizing beam splitter 3 Polarization control type liquid crystal 4 Polarization camera 5 Target sample 6 Linear polarizer 7 Objective lens B sample measurement device 40 Polarization camera C sample measurement device 8 λ / 4 plate

Claims

1. A light source, a polarization camera that receives reflected light reflected from a target sample and is light from the light source, and detects a horizontal linearly polarized component and a vertical linearly polarized component derived from the reflected light, a predetermined optical element that can branch light at a specific ratio while maintaining the polarization state, guides a part of the light emitted from the light source to the target sample, and guides a part of the reflected light to the polarization camera, a polarization conversion element disposed between the target sample and the predetermined optical element, having a plurality of sections capable of individually controlling the polarization of transmitted light, the polarization conversion element transmits, while maintaining the polarization state thereof, light among the reflected light that has a deviation in the optical path from the incident light to the target sample, and can convert the polarization state of the light to another polarization state according to the amount of deviation in the optical path and transmit it, a sample measurement device.

2. The polarization camera detects a 45° linearly polarized component and a 135° linearly polarized component derived from the reflected light. The sample measurement device according to Claim 1.

3. A phase plate that is detachably installed between the polarization camera and the predetermined optical element and imparts a predetermined phase difference to the light guided from the predetermined optical element to the polarization camera is provided. The sample measurement device according to Claim 2.

4. An electrically controlled birefringence variable polarization element that is installed between the polarization camera and the predetermined optical element and can impart a predetermined phase difference to the light guided from the predetermined optical element to the polarization camera by electrical control is provided. The sample measurement device according to Claim 2.

5. The Stokes parameters of the target sample can be obtained based on the information of the polarization components detected by the polarization camera. The sample measurement device according to Claim 3 or Claim 4.

6. The predetermined optical element is an unpolarized beam splitter. The sample measurement device according to Claim 1 or Claim 2.

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