WO2016027797A1 - Device for measuring material by using ghost imaging - Google Patents

Abstract

[Problem] To provide a device for measuring a material by using ghost imaging which is capable of measuring the optical properties of a material two-dimensionally. [Solution] A device for measuring a material is provided with: a light irradiation means 10; a detection means 20 for detecting light transmitted through a subject to be measured M or light reflected by the subject to be measured M; and a calculation means 30 for estimating the properties of the subject to be measured M on the basis of information on the light detected by the detection means 20 and information on irradiation light SL irradiated on the subject to be measured M. The light irradiation means 10 is provided with: a light source 11; and a polarization adjusting part 12 for periodically modulating the polarized state of light emitted by the light source 11 to form the irradiation light SL. The light source 11 has a function for emitting a plurality of pattern lights having different intensity distributions. The calculation means 30 is provided with a function for forming a ghost image of the subject to be measured M on the basis of information pertaining to the intensity distributions of the pattern lights and a timing when the pattern lights are emitted, and information pertaining to the intensity of the light detected by the detection means.

Description

Substance measurement equipment using ghost imaging

The present invention relates to a substance measuring apparatus using ghost imaging.

Conventionally, ellipsometry has been used for measuring the thickness of a thin film formed on the surface of an object, physical properties of the thin film, and the like (for example, Patent Document 1). Ellipsometry is a method for measuring the thickness of a thin film using the polarization of light. Specifically, in ellipsometry, light emitted from a light source is incident on a measurement object through a polarizer, and the transmitted light or reflected light is received by a detector through the analyzer. Since the polarization state of transmitted light and reflected light changes from incident light depending on the physical property of the measurement object, the physical property of the measurement object can be measured by calculating the amount of change in the polarization state. In recent years, a technique for changing the polarization of incident light by arranging a PEM (photoelastic modulator) between a polarizer and a measurement object has been developed. By using such a PEM, the amplitude ratio ψ and the phase difference Δ can be measured with high accuracy. Further, since the polarization can be changed at a high frequency, there is an advantage that the measurement time can be shortened.

However, in the case of ellipsometry, incident light can be irradiated only to a narrow area limited to be measured. In other words, ellipsometry can only measure points. For this reason, in the case of a measurement object having a certain size, in order to measure the physical properties of the entire measurement object using ellipsometry, the entire measurement object must be scanned. For this reason, ellipsometry has a problem that it takes a long time to measure the entire measurement object even if the measurement time at each point can be shortened using PEM.

By the way, there is ghost imaging as a method for measuring the physical properties of a measurement object two-dimensionally. Ghost imaging illuminates an object (measurement target) multiple times with a spatially modulated light intensity distribution, detects scattered light from the object with a point detector, and then images from the intensity correlation between the illumination light and the detected light It is a technique to do.

Conventionally, ghost imaging has been applied to three-dimensional shape measurement, fluorescence measurement, security field, etc., but an application example to polarization measurement has been reported (Non-Patent Document 1).

In Non-Patent Document 1, light emitted from a laser is illuminated on a diffuser plate, and circularly polarized light having a random light intensity distribution is generated using a polarizer and a wave plate. The circularly polarized light is illuminated onto the measurement object, the reflected light is separated into P-polarized light and S-polarized light by a polarization beam splitter, and the light intensity of each polarized light is measured using a point detector. Further, the circularly polarized light (that is, the illumination light of the measurement object) is branched before illuminating the measurement object, and is acquired by the CCD camera. In Non-Patent Document 1, correlation calculation between circularly polarized light and reflected light obtained by a CCD camera is performed 100,000 times, and then the sum and difference of the intensity of each polarized light are calculated to obtain an image for each polarization (ghost image). Is reproduced. And it succeeded in identifying a stone and a metal in a ghost image using the stone and the metal embedded in the tree as a measuring object.

Japanese Examined Patent Publication No. 7-81837

”Polarimetric Ghost Imaging“, D. Shi, S. Hu and Y. Wang: Opt. Lett., 39, No. 5 (2014) 1231-1234]

As in Non-Patent Document 1, if ghost imaging and polarization measurement can be combined, there is a possibility that the thickness of the thin film can be measured two-dimensionally. However, with the technique of Non-Patent Document 1, it is impossible to perform measurement using PEM, so it is difficult to measure the thickness of the thin film with high accuracy like ellipsometry. In addition, since the technique of Non-Patent Document 1 cannot measure the amplitude ratio ψ and the phase difference Δ, a ghost image of P-polarized light and S-polarized light can be formed. Cannot be grasped. Therefore, with the technique of Non-Patent Document 1, it is substantially difficult to measure the physical properties of the entire measurement object, such as ellipsometry.

In view of the above circumstances, an object of the present invention is to provide a substance measuring apparatus using ghost imaging capable of spatially measuring the structure, defects, optical characteristics, and the like inside an object to be measured.

According to a first aspect of the present invention, there is provided a substance measuring apparatus using ghost imaging, a light irradiation means for irradiating the object to be measured with irradiation light having a spatial intensity distribution, and light transmitted through the object to be measured or the object to be measured. Based on information on light detected by the detection means and information on irradiation light irradiated on the object to be measured, a property of the object to be measured is estimated. A light source that emits light having a spatial intensity distribution, and periodically modulates the polarization state of the light emitted by the light source to form the irradiation light. The light source has a function capable of emitting a plurality of pattern lights having different intensity distributions, and the calculation means includes the intensity distribution of the pattern lights and the pattern light. Is released The polarization parameter of each part of the object to be measured is calculated based on the information on the information and the information on the intensity of the light detected by the detection means, and a ghost image of the object to be measured is formed based on the polarization parameter. It has a function.
The substance measuring apparatus using ghost imaging according to a second aspect of the present invention is the material measuring apparatus according to the first aspect, wherein the light source has a longer period during which one pattern light is emitted than a period in which the polarization of the irradiation light is modulated. It is controlled to switch and emit a plurality of pattern lights.
The substance measuring apparatus using ghost imaging according to the third invention is characterized in that, in the first or second invention, the plurality of pattern lights emitted from the light source are circulation patterns.
The substance measuring apparatus using ghost imaging according to a fourth aspect of the present invention is the first, second or third aspect, wherein the polarization adjusting unit converts the light emitted from the light source into linearly polarized light, and the polarized light. A modulation unit that modulates the polarized light converted into linearly polarized light by the optical element into the irradiation light, and the detection means transmits light that is transmitted through the object to be measured or light that is reflected by the object to be measured. Is provided with a detector for converting the light into linearly polarized light.
A substance measuring apparatus using ghost imaging according to a fifth invention is characterized in that, in the fourth invention, the modulator is a photoelastic modulator.

According to the first invention, since the polarization parameter of each part of the measurement object can be obtained by the calculation means, a ghost image of the measurement object can be formed based on the polarization parameter. If such a ghost image is formed, it is possible to spatially grasp the structure, defects, optical characteristics, and the like inside the object to be measured based on the ghost image.
According to the second aspect of the present invention, it is possible to grasp the fluctuation of the light transmitted through the object to be measured or the light reflected by the object to be measured when the polarization of each pattern fluctuates for one period. Then, since the direct current component in the signal detected by the detection means can be properly grasped, the polarization parameter can be appropriately calculated, and a ghost image can be formed with high accuracy.
According to the third invention, since the plurality of pattern lights are circulation patterns, a ghost image of the polarization parameter can be formed in a short time.
According to the fourth aspect of the invention, since the light is modulated by the adjusting unit after passing through the polarizer, the polarization parameter can be measured with high accuracy.
According to the fifth aspect of the invention, stable phase modulation can be realized, so that the polarization parameter can be measured stably and with high accuracy. In addition, even when the phase difference angle is small, the phase difference angle can be measured with high accuracy, and the polarization can be changed at a high frequency, so that the measurement time can be shortened.

It is a schematic image figure of the state which is measuring the to-be-measured object M by the substance measuring apparatus 1 using the ghost imaging of this embodiment. It is a schematic block diagram of the substance measuring apparatus 1 using the ghost imaging of this embodiment. It is explanatory drawing of the sample employ | adopted in the Example. FIG. 6 is a diagram showing the results of Example 1. FIG. 6 is a diagram showing the results of Example 2. It is explanatory drawing of the to-be-measured object used for Example 3. FIG. It is the figure which showed the result of Example 3. It is the figure which showed the result of Example 3.

Next, an embodiment of the present invention will be described with reference to the drawings.
The substance measuring apparatus using ghost imaging according to the present invention is an apparatus that can measure physical properties of a measurement target based on the polarization state of light irradiated on the measurement target, and relates to a spatial polarization state distribution. It is characterized in that information can be obtained.

The substance measuring apparatus using ghost imaging of the present invention is applied to, for example, imaging of a cell structure by a microscope, analysis of a fine structure, detection of a defect, measurement of a thin film thickness and a thin film optical property (for example, a refractive index). can do. It can also be used for inspection in semiconductor processes (nanoimprinting and shape measurement and defect detection in ordinary exposure methods) and detection of minute dust, and its application is not particularly limited.

(Description of the substance measuring apparatus 1)
The substance measuring apparatus 1 of this embodiment is demonstrated based on drawing.
As shown in FIGS. 1 and 2, the substance measuring apparatus 1 according to the present embodiment includes a light irradiation means 10, a detection means 20, and a calculation means 30.

1, the measurement target M is disposed between the light irradiation means 10 and the detection means 20, and the measurement target M is irradiated from the light irradiation means 10 with the irradiation light SL. The detecting means 20 detects the transmitted light TL. However, a configuration may be employed in which the light to be measured M is irradiated with the irradiation light SL from the light irradiation means 10 and the detection means 20 detects the reflected light.

When detecting the transmitted light TL, there is an advantage that the internal information of the measurement target M can be measured. For this reason, the method of detecting the transmitted light TL is suitable for an internal structure inspection or an internal defect inspection of a transparent plastic molded product or a lens.

On the other hand, when the reflected light is detected, there is an advantage that only the surface information of the measurement target M can be measured compared to the transmitted light TL. For this reason, the method of detecting the reflected light TL is suitable for nanoimprinting, surface inspection of semiconductor devices, and the like.

(Light irradiation means 10)
As shown in FIG. 1, the light irradiation means 10 includes a light source 11, a polarizer 12, and a modulation unit 13.

The light source 11 is capable of emitting pattern light having a spatial light intensity distribution. Pattern light having a spatial light intensity distribution means light that is not uniform in intensity and forms portions with different intensities when the pattern light is irradiated onto a screen or the like to form a two-dimensional image. ing.

The light source 11 has a function of switching and emitting a plurality of pattern lights having different light intensity distributions. The plurality of pattern lights may have different light intensity distributions, and the light intensity distribution of each pattern light is not particularly limited. For example, as the plurality of pattern lights, those in which the light intensity distribution changes randomly when the plurality of pattern lights are switched and irradiated onto the screen or the like can be adopted.

As such a light source 11, for example, a liquid crystal projector, a DLP type projector, or the like can be used, but it is not particularly limited as long as it has the functions described above.

It should be noted that if pattern light having a cyclic pattern using a Hadamard matrix is employed, there is an advantage that the calculation means 30 can shorten the time for forming the ghost image of the polarization parameter. In order to improve the accuracy of the ghost image, it is preferable that the number of pattern lights is large. However, when the number of pattern lights increases, it takes time to measure. However, if the cyclic pattern light is used, the number of pattern lights to be used can be reduced, so that the measurement time can be shortened.

Also, in order to increase the spatial resolution of the ghost image, that is, the spatial resolution of the measurement location of the measurement target M, it is desirable to reduce one pixel of the pattern light to near the diffraction limit.

(Polarizer 12 and modulator 13)
As shown in FIG. 1, the polarizer 12 and the modulation unit 13 are arranged in this order from the light source 11 toward the measurement target M between the light source 11 and the measurement target M.

The polarizer 12 converts light emitted from the light source 11, that is, pattern light, into linearly polarized light. For example, the polarizer 12 is disposed so that the direction of the transmission axis is 45 ° with respect to the transmission axis of the photoelastic modulator 13.

The modulator 13 modulates the polarization state of the polarized light converted by the polarizer 12 to form the irradiation light SL that irradiates the measurement target M. Specifically, linearly polarized light is periodically changed from linearly polarized light, and the polarization state of the irradiation light SL is changed in the order of linearly polarized light, elliptically polarized light, circularly polarized light, elliptically polarized light, and linearly polarized light. It is. The modulator 13 is not particularly limited as long as it has a function as described above. For example, a photoelastic modulator (PEM) can be used. A photoelastic modulator is composed of a transparent and high-quality optical crystal such as quartz and a piezoelectric element. When a periodic voltage is applied to the piezoelectric element, the piezoelectric element expands and contracts and stress is applied to the optical crystal. This causes birefringence due to photoelasticity. In the photoelastic modulator, since birefringence can be controlled by the applied voltage, stable phase modulation can be realized, so that the polarization parameter can be measured stably and with high accuracy. In addition, if the measurement target M is irradiated with the irradiation light SL whose polarization state is modulated by the photoelastic modulator, the intensity of the measurement light is modulated at the modulation frequency, so that the phase difference angle Δ of the measurement target M is small. However, the phase difference angle Δ can be accurately measured. And since a photoelastic modulator can change polarization | polarized-light at a high frequency, the advantage that a measurement time can be shortened is also acquired.

Note that the polarizer 12 may not be provided when the linear polarization degree of the light source 11 is good, but it is preferable to provide the polarizer 12 in that the reliability of the measurement value can be increased.

(Detecting means 20)
As shown in FIG. 1, the detection means 20 includes a light detection unit 21 and an analyzer 22.

(Photodetector 21)
The light detection unit 21 includes a light detector 21a that detects the transmitted light TL that has passed through the measurement target M, and a lens 21b that collects the transmitted light TL and supplies it to the light detector 21a.

The light detector 21a detects the intensity of the transmitted light TL collected by the lens 21b. That is, the photodetector 21a is configured to measure the light intensity that is the sum of the intensities of the transmitted light TL transmitted through the measurement target M. The photodetector 21a is not particularly limited as long as it can measure the intensity of light. For example, a photomultiplier tube or a photodiode can be used as the photodetector 21a.

The lens 21b is capable of condensing all the transmitted light TL transmitted through the measurement target M and supplying it to the photodetector 21a. As this lens 21b, a known condensing lens can be used.
In addition, it is desirable to condense all the transmitted light TL transmitted through the measurement target M onto the photodetector 21a. However, when all the transmitted light TL cannot be collected on the photodetector 21a due to the size of the measurement target M or the layout restrictions of each part, a part of the transmission light TL transmitted through the measurement target M Only the transmitted light TL may be condensed on the photodetector 21a. Even in this case, the transmitted light TL in an appropriate range is condensed on the photodetector 21a in accordance with the purpose of measurement, such as a part where there is a high possibility that an important part of the measurement target M or a defect exists. What should I do?

(Analyzer 22)
As shown in FIG. 1, an analyzer 22 is provided between the light detection unit 21 and the measurement target M. The analyzer 22 converts the transmitted light TL transmitted through the measurement target M into linearly polarized light. The analyzer 22 is arranged so that the direction of the transmission axis is parallel to the transmission axis of the polarizer 12. For example, when the direction of the transmission axis of the polarizer 12 is 45 ° with respect to the polarization axis of the photoelastic modulator 13, the analyzer 22 also has the direction of the transmission axis of the photoelastic modulator 13. It is arrange | positioned so that it may become 45 degrees with respect to the polarization axis.

(Calculation means 30)
As shown in FIG. 2, the calculation means 30 is electrically connected to the light source 11 of the light irradiation means 10, the modulation section 13, and the light detection section 21 of the detection means 20, and various information is received from the light source 11 and the like. It comes to be supplied.

The light source 11 is provided with a control unit that controls pattern light emitted from the light source 11, and information on the pattern light emitted from the light source 11 is supplied from the control unit. The pattern light information includes the light intensity distribution of each pattern light, the time when each pattern light is emitted (emission timing, emission period, etc.), the wavelength of light emitted from the light source 11, and the like.
Also, information such as the modulation frequency and phase of the modulation unit is supplied from the modulation unit 13.
The light detection unit 21 supplies information such as the detected light intensity and measurement timing, and the detected light wavelength.

The computing unit 30 includes a polarization parameter calculation unit 31, a physical property estimation unit 32, a ghost image formation unit 33, and a storage unit 34, so that each unit processes information from the light source 11 and the like. It has become. The storage unit 34 has a function of storing information processed by each unit, information necessary for processing, and the like.

(Polarization parameter calculation unit 31)
First, the polarization parameter calculation unit 31 is based on the information on the pattern light emitted from the light source 11 and the information on the light (detection light) detected by the light detection unit 21 of the detection unit 20. It has a function of calculating the polarization parameter at each position.

Specifically, the polarization parameter calculation unit 31 has a function of obtaining a cross-correlation between the pattern light and the detection light at each position and each time of the measurement target M. The cross correlation result is subjected to a Fourier transform such as FFT, and the result obtained by the Fourier transform is used to calculate the phase difference angle Δ and the amplitude ratio ψ, which are polarization parameters.

First, the polarization parameter calculation unit 31 calculates a cross-correlation function between the pattern light and the detection light at each position and time of the measurement target M. The cross-correlation function at each position of the measurement target M can be obtained by the following equation. Note that n indicates the number of pattern light.

G (x, y, t) = <I ₁ (x, y, n) I ₂ (t, n)>-<I ₁ (x, y, n)><I ₂ (t, n)>

Next, Fourier transform such as FFT is performed on the cross-correlation function obtained at each position of the measurement target M. Then, the direct current component I _dc of the light intensity fluctuation at each position, the primary frequency component I _1f, and the secondary frequency component I _2f can be obtained.

If the direct current component I _dc of the light intensity fluctuation at each position, the primary frequency component I _1f and the secondary frequency component I _2f are obtained, the phase difference angle Δ and the amplitude ratio ψ are obtained by the following equations. be able to.

Phase difference angle Δ = tan ^-1 (-0.432I _1f /0.519I _2f )
Amplitude ratio ψ = 1 / 2sin ^-1 ((I _1f /1.038I _dc ) ² + (I _2f /0.864I _dc ) ² )

In the above example, Fourier transformation was performed on the cross-correlation function. However, the cross-correlation function may be calculated for the Fourier-transformed data after performing the Fourier transform on the pattern light and the detection light, respectively. In this case, there is an advantage that the calculation speed is improved as compared with the case where the Fourier transform is performed on the cross correlation function. On the other hand, when the Fourier transform is performed on the cross-correlation function as described above, there is an advantage that the control system is simplified.

(Physical property estimation unit 32)
The physical property estimation unit 32 has a function of calculating the characteristics of each part of the measurement target M based on the polarization parameters (phase difference angle Δ and amplitude ratio ψ) calculated by the polarization parameter calculation unit 31. Specifically, the physical property estimation unit 32 calculates the characteristics of each part of the measurement target M using the information stored in the storage unit 34 and the polarization parameter.

For example, when measuring an object to be measured having a fine shape, a polarization parameter that changes due to the fine shape of the object to be measured is stored in the storage unit 34 in advance. Then, if the measured polarization parameter is processed as follows using the relationship between the fine shape stored in the storage unit 34 and the polarization parameter, a ghost image (2) of the fine shape of the measurement object. Dimensional images).

(Ghost image forming unit 33)
The ghost image forming unit 33 includes each polarization parameter (phase difference angle Δ and amplitude ratio ψ) obtained by the polarization parameter calculation unit 31, an ellipso parameter Δψ, and an object to be measured obtained by the physical property estimation unit 32. It has a function of making the characteristic of M a two-dimensional image as a ghost image. That is, since each polarization parameter and the like are associated with the position of the measurement target M, the two-dimensional configuration is such that each position of the measurement target M has a color and brightness corresponding to the value of the polarization parameter and the like at each position. The ghost image forming unit 33 has a function of forming an image. Then, since the distribution of the polarization parameter and the like of the measurement object M can be visualized, the polarization parameter and the like of the measurement object M can be grasped spatially.

As described above, according to the substance measuring apparatus 1 of the present embodiment, if a plurality of pattern lights having a spatial light intensity distribution are emitted from the light source 11 of the light irradiation means 10 to irradiate the measurement target M, A ghost image of the measurement target M can be formed.
In addition, the irradiation light SL applied to the measurement target M is obtained by periodically modulating the polarization of the plurality of pattern lights emitted from the light source 11, so that the polarization parameters of each part of the measurement target M are grasped. it can.
Then, based on the polarization parameter, it is possible to form a ghost image that two-dimensionally displays the structure, defects, optical characteristics, and the like of each part of the measurement target M. Therefore, the measurement target is based on the ghost image. The internal structure, defects, optical characteristics, etc. can be grasped spatially.

The light source 11 emits the plurality of pattern lights so that the period during which one pattern light is emitted is longer than the period of modulating the polarization of the irradiation light SL by the modulation unit 13 that switches and emits the plurality of pattern lights. It is desirable to be controlled to switch and release. In this case, any pattern light always changes in the polarization for one period while the pattern light is emitted, so that the fluctuation of the light intensity of the detection light when the one-period polarization fluctuates can be grasped by all the pattern lights. . That is, since the light intensity of the detection light in all polarization states can be grasped for all the pattern lights, the direct current component I _dc included in the signal detected by the detection means 20 can be grasped appropriately. Therefore, since the polarization parameter can be calculated using the light intensity signal from which the DC component has been removed, the polarization parameter can be calculated appropriately, so that a ghost image can be formed with high accuracy.

It was confirmed by numerical simulation that the polarization parameter of the object to be measured can be obtained spatially by the apparatus of the present invention.

The sample (object to be measured) used in the numerical simulation is (1) a sample having a fixed phase difference angle Δ30 degrees and having an amplitude ratio ψ in FIG. 3B, and (2) a phase difference angle Δ in FIG. , A sample with an amplitude ratio ψ fixed at 30 degrees, (3) a sample of the phase difference angle in FIG. 3A and the amplitude ratio ψ in FIG. 3B. For this sample, a ghost image having a phase difference angle Δ and an amplitude ratio ψ was created when a random pattern light was irradiated.

Numerical simulation was performed under the following calculation conditions using National Instruments Lab View.

Modulation frequency: 50000Hz
Number of sampling: 10000 times Sampling cycle: 500 ns
Number of times of illumination: 10,000 times Pattern size: 10 × 10pixel
Dot size: 1 x 1 pixel

The number of samplings corresponds to the number of times the detection means measures the intensity of the detection light, and the sampling period is a time interval for measuring the detection light. The number of times of irradiation corresponds to the number of irradiated pattern lights.

The results are shown in FIG.
As shown in FIG. 4, it was confirmed that the phase difference angle Δ and the amplitude ratio ψ of the sample can be acquired, and a ghost image of the phase difference angle Δ and the amplitude ratio ψ can be created. Then, it was confirmed that the acquired phase difference angle Δ and amplitude ratio ψ almost coincided with the phase difference angle Δ and amplitude ratio ψ set in the sample.

The effect of the number of pattern lights on the polarization parameter of the object to be measured was confirmed by numerical simulation.

The sample (object to be measured) used in the numerical simulation is the sample (3) of Example 1 (the sample having the phase difference angle in FIG. 3A and the amplitude ratio ψ in FIG. 3B). This sample was irradiated with pattern light of a random pattern, and the number of times of illumination (that is, the number of pattern lights) was changed to create a ghost image with a phase difference angle Δ and an amplitude ratio ψ.

Numerical simulation was performed under the following calculation conditions using National Instruments Lab View.

Modulation frequency: 50000Hz
Number of sampling: 10000 times Sampling cycle: 500 ns
Number of times of illumination: 100, 1000, 10,000 times Pattern size: 10 × 10pixel
Dot size: 1 x 1 pixel

The number of samplings corresponds to the number of times the detection means measures the intensity of the detection light, and the sampling period is a time interval for measuring the detection light. The number of times of irradiation corresponds to the number of irradiated pattern lights.

The results are shown in FIG.
As shown in FIG. 5, it was confirmed that the phase difference angle Δ and the amplitude ratio ψ acquired by increasing the number of illuminations approached the phase difference angle Δ and the amplitude ratio ψ set in the sample.

Actually, the apparatus of the present invention was configured, and it was confirmed that the spatial parameters of the surface of the measurement object can be measured.

In the experiment, a gold (Au) plate and a silicon (Si) plate were used as objects to be measured, and the region surrounded by a dotted line (about 35 mm × 18 mm) in FIG. Detected. Then, based on the detected information (light intensity) of the reflected light, a ghost image of the phase difference angle was formed.

The following equipment was laid out so that the apparatus used for the experiment was arranged substantially equivalent to FIG.
The apparatus used in the experiment is different from FIG. 1 in that the reflected light is measured.

1) Light source: Liquid crystal projector (made by 3M, model number: MP410)
2) Polarizer: Made by Thorlabs: Model number CRM1P1M
3) Photoelastic modulator (PEM): manufactured by HINDS instruments, model number: PEM-100
4) Analyzer: manufactured by Thorlabs, model number: CRM1P1M
5) Lens: Sigma Kogyo, Model: SLB-50-70P
6) Photodetector: Photodiode (manufactured by Hamamatsu Photonics, model number: S1336-44BK)

As in the case of Example 1, random pattern light was used as the pattern light emitted from the light source. The pattern light emitted from the light source was controlled by a program created by the control program labview.
The information of the reflected light detected by the photodetector was analyzed by a program created by the control program labview to form a phase difference ghost image.

The experimental conditions are as follows.

Modulation frequency: 42.08 Hz
Sampling number: 50 MHz
Sampling period: 20 ns
Number of times of illumination: 46000 times Pattern size: 25 × 25pixel
Dot size: 2pixel
average number: 64 times
The number of samplings corresponds to the number of times the photodetector has measured the intensity of the reflected light, and the sampling period is a time interval for measuring the reflected light. The number of times of irradiation corresponds to the number of irradiated pattern lights.
“Average number” is the number of times of averaging per pattern. In this case, since the number of times of illumination is 46000 times and the average number is 64 times, the total number of times of illumination is 46000 patterns × 64 times.

The results are shown in FIG. 7 and FIG.
FIG. 7 shows a spatial image of the direct current component, the primary frequency component, and the secondary frequency component of the light intensity fluctuation of the detected reflected light. Thus, it was confirmed that each component at each position of the measurement target can be measured by using the apparatus of the present invention.

Then, when a ghost image of the phase difference angle of the measurement target is formed using each component at each position of the measurement target, FIG. 8 is obtained.
As can be seen from FIG. 8, it was confirmed that the boundary between the Au portion and the Si portion could be clearly recognized, and that the difference in materials could be recognized using the apparatus of the present invention.
In addition, it was confirmed that even in the Au region and in the Si region, a difference in the phase difference angle can be confirmed depending on the position, and a difference in surface properties can be detected in each region.

The substance measuring apparatus using ghost imaging of the present invention is suitable for photographing a cell structure with a microscope, detecting a defect of a fine structure, and measuring a thin film thickness and a thin film optical property.

DESCRIPTION OF SYMBOLS 1 Substance measuring apparatus 10 Light irradiation means 11 Light source 12 Polarizer 13 Modulation part 20 Detection means 21 Photodetection part 22 Analyzer 30 Calculation means 31 Polarization parameter calculation part 32 Physical property estimation part 33 Ghost image formation part M Object to be measured SL irradiation Light TL Transmitted light

Claims (5)

A light irradiation means for irradiating the object to be measured with irradiation light having a spatial intensity distribution;
Detecting means for detecting light transmitted through the object to be measured or light reflected from the object to be measured;
Calculating means for estimating the property of the object to be measured based on the information on the light detected by the detecting means and the information on the irradiation light irradiated on the object to be measured; and
The light irradiation means includes
A light source that emits light having a spatial intensity distribution;
A polarization adjustment unit that periodically modulates the polarization state of the light emitted from the light source to form the irradiation light, and
The light source is
It has a function that can emit a plurality of pattern lights having different intensity distributions,
The computing means is
Based on the information on the intensity distribution of the pattern light and the timing at which the pattern light is emitted, and the information on the intensity of the light detected by the detection means, the polarization parameter of each part of the object to be measured is calculated, and the polarization A substance measuring apparatus using ghost imaging, which has a function of forming a ghost image of the object to be measured based on a parameter. The light source is
The control is performed so that the plurality of pattern lights are switched and emitted so that a period during which one pattern light is emitted is longer than a period in which the polarization of the irradiation light is modulated. A substance measuring device using the described ghost imaging. The substance measuring apparatus using ghost imaging according to claim 1, wherein the plurality of pattern lights emitted from the light source are circulation patterns. The polarization adjusting unit is
A polarizer that converts light emitted from the light source into linearly polarized light;
A modulation unit that modulates the polarized light converted into linearly polarized light by the polarizer into the irradiation light, and
The detection means includes
The ghost imaging according to claim 1, 2 or 3, further comprising a detector for converting light transmitted through the object to be measured or light reflected by the object to be measured into linearly polarized light. Substance measuring device. The substance measuring apparatus using ghost imaging according to claim 4, wherein the modulation unit is a photoelastic modulator.

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