KR20210151585A - Apparatus for measuring reflectivity and incident light - Google Patents

Abstract

The present invention relates to a device for measuring reflectivity and incident light quantity. More specifically, according to an embodiment of the present invention, the device comprises: a light source; a light splitter for splitting the light source into a first beam heading toward a sample and a second beam separated from the first beam; a phase delayer for delaying the phase of the second beam split by the light splitter; a light detector for detecting a reflective beam generated by reflecting the first beam on a sample and the second beam having passed the phase delayer; a first polarizer arranged between the light source and the phase delayer; a second polarizer arranged between the phase delayer and the light detector; and a signal processing part for separating a signal, which is detected by the light detector, into a low-frequency signal and a high-frequency signal to obtain a signal and obtaining the reflectivity and incident light quantity of the sample from the low-frequency signal and the high-frequency signal. Therefore, provided is a device for measuring reflectivity and incident light quantity, wherein information on reflectivity and incident light quantity can be detected in real time.

Description

Apparatus for measuring reflectivity and incident light

The present invention relates to an apparatus for measuring reflectance and incident light, particularly by using a phase retarder and a polarizing plate to modulate information on the amount of incident light or reflected light into a high-frequency signal, and detect reflectance and incident light amount information in real time through frequency analysis It relates to an apparatus for measuring reflectance and incident light quantity that can be

A reflectometer is an equipment that obtains information about the thickness of a sample by measuring the intensity ratio (reflectivity) of incident light and reflected light when light is reflected from a sample. This reflectivity measurement proceeds through two processes. First, the intensity of incident light (incident light quantity) is measured. Second, after the same amount of light is incident on the sample to be measured, the amount of reflected and returned light is measured to measure the reflectivity. Therefore, when the amount of incident light changes during measurement, the first process is performed again to measure the amount of incident light again, so that reflectance measurement without distortion is possible.

1 shows the structure of a typical reflectometer.

The light irradiated from the light source 1 is incident on the sample 4 through the beam splitter 2 and the objective lens 3 . And the light reflected from the sample 4 is detected using a wavelength detector such as a spectrometer 5 (spectrometer). Since the reflected light is given by the product of the incident light amount and the reflectivity, the reflectivity of the sample 4 can be known by measuring the incident light amount and the reflected light amount of the reflected light. Specifically, first, if the amount of reflected light is measured using a reference specimen for which optical information is known, the amount of incident light can be calculated inversely using the already known reflectivity. Next, the sample 4 to be measured is measured. Since the amount of incident light is calculated, if the amount of reflected light of the light reflected from the sample 4 is measured, the reflectivity of the sample 4 can be measured using the amount of the incident light of the sample 4 .

However, a problem that occurs here is that the time interval for measuring the amount of incident light and the time for measuring the sample 4 are different, so there is a time interval. The value of the light source 1 changes depending on the external temperature, and in particular, preheating for about 1 hour is required in the process of operating the equipment for the first time. In addition, the intensity of the light source 1 is gradually weakened even if the same power is given due to the lifespan. Due to this influence, there is a difference between the calculated amount of incident light and the actual amount of incident light, and the reflectivity due to the difference in the amount of incident light is distorted by that much, resulting in an error in the thickness value of the sample 4 make it

This distortion of reflectivity has a great effect on a thin thin film in which the reflectivity signal is monotonous, and sometimes shows an error of 30% or more. In addition, in the conventional method as described above, when the amount of light needs to be changed due to a change in the sample 4 , it is necessary to repeat the measurement of the amount of incident light by the first process, thereby complicating the measurement process.

In order to solve the conventional problem, a detector for measuring the amount of light in real time can be used separately, but since the parameter values of the detector for measuring the amount of light and the spectrometer 5 for measuring the amount of reflected light are different, they need to be corrected and , which has the disadvantage of increasing the cost of measuring equipment. On the other hand, when the method of continuously correcting the amount of light is adopted, there is a limitation in that the measurement sequence is increased and this is also not a real-time measurement.

The present invention has been devised to improve the above-described problems. In particular, by using a phase delay and a polarizing plate, information on the amount of incident light or amount of reflected light is modulated into a high-frequency signal, and information on reflectivity and incident light is displayed in real time through frequency analysis. An object of the present invention is to provide an apparatus for measuring reflectance and incident light that can be detected by .

According to an aspect of the present invention, there is provided an apparatus for measuring reflectivity and incident light quantity, comprising: a light source; a light splitter for splitting the light source into a first beam directed toward the sample and a second beam separated from the first beam; a phase delayer for delaying the phase of the second beam divided by the optical splitter; a photodetector configured to detect the reflected beam from which the first beam is reflected by the sample and the second beam that has passed through the phase retarder; a first polarizer disposed between the light source and the phase retarder; a second polarizer disposed between the phase retarder and the photodetector; and a signal processing unit configured to obtain a signal by separating a low-frequency signal and a high-frequency signal from the signal detected by the photodetector, and to obtain the reflectivity and the incident light amount of the sample from the low-frequency signal and the high-frequency signal.

In addition, it is preferable that the phase retarder is a multi-order retarder.

In addition, it is preferable that the first polarizer and the light splitter are integrated into a polarization beam splitter that simultaneously performs polarization and splitting of the light source.

On the other hand, according to another aspect of the present invention, an apparatus for measuring reflectance and incident light may include: a light source; a light splitter for splitting the light source into a first beam directed toward the sample and a second beam separated from the first beam; a phase delayer for delaying the phase of the second beam divided by the optical splitter; a reflective mirror disposed at the rear end of the phase delay unit to reflect the second beam passing through the phase delay unit and to proceed to the phase delay unit again; a photodetector configured to detect the reflected beam of the first beam reflected by the sample and the second beam passing through the phase delay unit; a first polarizer disposed between the light source and the reflective mirror; and a signal processing unit configured to obtain a signal by separating a signal detected by the photodetector from a low-frequency signal and a high-frequency signal, and to obtain a reflectivity of the sample and an incident light amount from the low-frequency signal and the high-frequency signal.

Here, the phase retarder is preferably a multi-order retarder.

Here, it is preferable that the first polarizer and the light splitter are integrated into a polarization beam splitter that simultaneously performs polarization and splitting of the light source.

On the other hand, according to another aspect of the present invention, an apparatus for measuring reflectance and incident light is provided, comprising: a light source; a light splitter for splitting the light source into a first beam directed toward the sample and a second beam separated from the first beam; a phase retarder for delaying the phase of the first beam divided by the optical splitter; a photodetector configured to detect a reflected beam from which the first beam is reflected by the sample and the second beam having incident light amount information; a first polarizer disposed between the sample and the photodetector; and a signal processing unit configured to obtain a signal by separating a signal detected by the photodetector from a low-frequency signal and a high-frequency signal, and to obtain a reflectivity of the sample and an incident light amount from the low-frequency signal and the high-frequency signal.

In addition, it is preferable that the phase retarder is a multi-order retarder.

In addition, it is preferable that the first polarizer and the light splitter are integrated into a polarization beam splitter that simultaneously performs polarization and splitting of the light source.

The apparatus for measuring reflectivity and incident light quantity according to the present invention can measure the incident light quantity and the reflected light quantity at the same time every time it is measured without going through a separate process for measuring the incident light quantity.

Since the amount of incident light can be detected each time it is measured, changes in the amount of light due to temperature or lifetime can be detected. to provide.

Because it is possible to measure the amount of light in real time, the distortion of the reflectance is reduced and the measurement accuracy of the reflectometer is improved. This effect is particularly useful for samples with monotonous reflectivity, such as thin films. In the case of a sample having a conventional monotonous reflectivity, a small error in the amount of incident light gives a big difference to the shape of the reflectivity, so that an erroneous thickness value is calculated. However, according to the present invention, more precise reflectivity measurement is possible, so that a thickness value can be precisely extracted.

As a result, the user can check the amount of incident light in real time without a separate process of measuring the amount of incident light, and the accuracy of reflectivity is remarkably improved, so that the thickness of the sample can be precisely calculated.

1 is a schematic view of a conventional reflectometer;
2 is a conceptual diagram of an apparatus for measuring reflectance and incident light according to an aspect of the present invention;
3 is measurement data for each thickness of the sample;
Figure 4 is a view showing the standard deviation of the actual thickness and the measured thickness of the sample of Figure 3;
5 is a graph showing the linearity of the sample thickness values obtained by the present invention;
6 is a conceptual diagram of an apparatus for measuring reflectance and incident light according to another aspect of the present invention;
7 is a conceptual diagram of an apparatus for measuring reflectance and incident light according to another aspect of the present invention;
8 is a block diagram showing a process of acquiring an incident light amount and reflectivity by a signal processing unit according to the present invention.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a conceptual diagram of an apparatus for measuring reflectance and incident light according to an aspect of the present invention. FIG. 3 is the measurement data for each thickness of the sample, FIG. 4 is a diagram showing the standard deviation of the actual thickness and the measured thickness of the sample of FIG. 3, and FIG. 5 is a graph showing the linearity of the sample thickness value obtained by the present invention . 6 is a conceptual diagram of a reflectance and incident light quantity measuring apparatus according to another aspect of the present invention, and FIG. 7 is a conceptual diagram of a reflectivity and incident light quantity measuring apparatus according to another aspect of the present invention. 8 is a block diagram showing the process of the signal processing unit acquiring the incident light amount and reflectivity according to the present invention.

An apparatus for measuring reflectance and incident light according to an embodiment of the present invention includes a light source 10 , a first polarizer 20 , a light splitter 30 , a phase delay unit 50 , a photodetector 60 , and a second polarizer 70 , and a signal processing unit 80 .

The light source 10 is provided to emit light. As the light source 10 , various sources such as a tungsten-halogen lamp and a Xe lamp may be used.

The first polarizer 20 is provided at a rear end of the light source 10 to polarize the light source 10 . The first polarizer 20 polarizes the light source 10 into light having a specific component before passing through the phase retarder 50 provided at the rear end of the first polarizer 20 . The light source 10 is polarized by the first polarizer 20 because polarized light is required to modulate a component of the light to a high frequency using the phase delay.

The light splitter 30 is provided to split the light source 10 . The light splitter 30 splits the light source into a first beam directed toward the sample and a second beam separated from the first beam. According to the present embodiment, the light splitter 30 is provided at the rear end of the first polarizer 20 and splits the polarized light to have a specific component into a first beam and a second beam. The first polarizer 20 and the light splitter 30 may be integrated and implemented by a polarizing beam splitter that simultaneously polarizes and splits the light source.

In addition, according to the present embodiment, the objective lens 40 is provided to irradiate the first beam split by the light splitter 30 to the sample 100 . The first beam is irradiated to the sample 100 after passing through the objective lens 40, is reflected from the sample 100, passes through the objective lens 40 again, passes through the optical splitter 30, and additionally It may be configured to enter the photodetector 60 using an optical path converting means. As shown in FIG. 2 , the first beam passing through the light splitter 30 may use a plurality of mirrors 110 to configure an optical system so that the first beam flows into the photodetector 60 . Of course, the manner in which the first beam enters the photodetector 60 is not limited to the manner in FIG. 2 .

In this way, the light source 10 is reflected on the sample 100 through the light splitter 30 and the objective lens 40, and again passes through the light splitter 30 to the photodetector 60 to configure a path. , a path along which the first beam moves may be defined as a first path. Since the first beam is reflected by the sample 100 while moving along the first path, reflectivity information of the sample 100 is included in the first beam.

The phase retarder 50 (Retarder) is provided to delay the phase of the second beam divided by the light splitter 30 . According to this embodiment, the phase retarder 50 is a multi-order retarder. The multi-order retarder is a phase delay that generates a phase delay of one wavelength or more, and serves to modulate the second beam divided by the optical splitter 30 into a high-frequency signal.

The photodetector 60 is provided to detect a reflected beam that is returned after being reflected by the sample 100 , and also to detect the second beam that has passed through the phase delay unit 50 .

The second polarizer 70 is a polarizer through which the second beam passing through the phase retarder 50 passes before entering the photodetector 60 . The second polarizer 70 is provided for polarization analysis of the second beam passing through the phase retarder 50 .

The signal processing unit 80 performs a Fourier transform on the signal detected by the photodetector 60 to obtain a separate low-frequency signal and a high-frequency signal, and performs an inverse Fourier transform on each of the low-frequency signal and the high-frequency signal, It is provided to obtain the amount of light and reflectivity of the sample 100 . That is, the signal processing unit 80 may extract information on the amount of incident light and reflectivity at a time in real time through frequency analysis.

As such, the second beam enters the photodetector 60 through the phase retarder 50 and the second polarizer 70, which is defined as a second path. As the second beam moves along the second path, a phase delay is generated, and the second beam is modulated with a high frequency to include information on the amount of incident light.

The light source 10 is split into a first beam and a second beam by the light splitter 30 , and the first beam includes reflectance information of the sample 100 while being reflected by the sample 100 , and the second beam The second beam is modulated into a high-frequency signal through a multi-order retarder so that information on the amount of incident light of the beam is not mixed with the reflectivity information. Since polarized light is required to use the multi-order retarder, a first polarizer 20 is disposed at the front end of the multi-order retarder, and a second polarizer 20 is disposed for analysis of polarization before entering the photodetector 60 . It passes through the polarizer 70 .

For example, when the first and second polarizers are aligned at 45° and the fast axis of the multi-order retarder is aligned at 0°, the intensity of light detected by the photodetector 60 is given as follows.

[Equation 1]

Detected light intensity = [I(λ)×{RF(λ) - cos(Phase(λ))+1}]/8

Here, I(λ) is the intensity of light according to the wavelength. That is, I(λ) means the amount of incident light. RF(λ) is the reflectivity of the sample 100 for each wavelength. And, Phase (λ) means a phase difference of the multi-order retarder for each wavelength. Phase(λ) increases the change value for each wavelength by the multi-order retarder, and the part multiplied by cos(Phase(λ) is modulated into a high-frequency signal. Therefore, if the above signal is separated into a high-frequency signal and a low-frequency signal, the following is same.

[Equation 2]

[I(λ)×{RF(λ) - cos(Phase(λ))+1}]/8

= [I(λ)×{RF(λ) +1}]/8 - {I(λ)×cos(Phase(λ))}/8

In Equation 2, the term [I(λ)×{RF(λ) +1}]/8 of the front end includes a low-frequency signal, and the term of the rear end, {I(λ)×cos(Phase(λ))}/ 8 contains high-frequency signals. As shown in FIG. 9 , the signal processing unit 80 may obtain each signal by Fourier transforming the signal and selectively filtering low frequency or high frequency components. Therefore, it is possible to obtain I(λ), which is the amount of incident light in the high-frequency signal, and in the low-frequency signal, it is possible to obtain the RF(λ), which is the reflectivity of the sample 100, using the amount of incident light I(λ) obtained from the high-frequency signal. .

In this way, when the amount of incident light and the reflectivity of the sample 100 are obtained, the thickness of the sample 100 can be calculated using these. Calculating the thickness of the sample 100 is according to the known bar and is not related to the technical configuration of the present invention, so a detailed description thereof will be omitted.

3 to 4 are data obtained by measuring the thickness of a thin film using the apparatus for measuring reflectivity and incident light according to the present embodiment.

3 is a summary of the thickness measurement data by applying the conventional method and the method according to the present invention with respect to the sample 100 having a thickness of 30 nm, 50 nm, 70 nm, 100 nm, 200 nm, 500 nm, and 1000 nm. In Fig. 3, each step in step 1, step 2, and step 3 is measured 20 times at different light intensity levels and the average value is recorded. That is, step 1 records the average value after 20 measurements, step 2 records the average value after another 20 measurements, and step 3 records the average value after another 20 measurements. The conventional method assumes that the amount of incident light is fixed and measures the thickness. 4 is a graph showing the standard deviation of the actual thickness and the measured thickness for each thickness of FIG. 3 .

As shown in FIGS. 3 and 4, when the measuring apparatus for reflectivity and incident light according to the embodiment is applied to the present invention, the measured thickness of the thin film is significantly reduced from the actual thickness and the standard deviation is significantly reduced compared to the prior art. It has been verified that data can be provided.

5 is a graph showing the actual thickness and the measured thickness of the sample 100. As shown in FIG. 5, when the measuring apparatus for reflectivity and incident light according to the present invention is applied, the measured thickness in a thin film shows linearity It can be seen that shows That is, it can be seen that the error between the actual thickness of the sample 100 and the measured thickness is significantly reduced. In the conventional method, the lack of linearity shows that the error with the actual thickness is large, and it means that other additional corrections are needed to secure the precision of the measurement.

Meanwhile, as shown in FIG. 6 , an apparatus for measuring reflectance and incident light according to another aspect of the present invention includes a light source 10 , a first beam pointing the light source 10 toward a sample, and the first beam and A light splitter 30 for splitting the divided second beam, a phase retarder 50 for delaying the phase of the second beam split by the light splitter, and a rear end of the phase retarder 50, A reflection mirror 90 that reflects the second beam passing through the phase delay unit 50 and propagates back to the phase delay unit 50, and the reflection of the first beam reflected by the sample 100 A beam, a photodetector 60 that detects the second beam reflected by the reflection mirror 90 and passed through the phase retarder 50 and the light splitter 30, the light source 10 and the reflection The first polarizer 20 disposed between the mirrors 90 and the signal detected by the photodetector 60 are separated from the low-frequency signal and the high-frequency signal to obtain a signal, and from the low-frequency signal and the high-frequency signal, the sample ( 100) and a signal processing unit 80 to obtain the reflectivity and the incident light amount.

In the embodiment according to Fig. 6, the same reference numerals are given to components that perform the same operations as in Fig. 2, and detailed descriptions thereof are omitted. According to the embodiment of FIG. 6 , the light source 10 , the light splitter 30 , the objective lens 40 , the first polarizer 20 , the phase retarder 50 , the reflection mirror 90 , and the photodetector 60 . ), and the signal processing unit 80 are substantially the same in terms of configuration and operation according to the embodiment of FIG. 2 . As the phase delay unit 50, a multi-order phase delay unit 50 is also used as shown in FIG.

However, according to the embodiment of FIG. 6 , the position of the first polarizer 20 is disposed between the light source 10 and the reflective mirror 90 , and the reflective mirror 90 is disposed at the rear end of the phase retarder 50 . are placed Accordingly, the light splitter 30 splits the light source 10 into a first beam and a second beam, and the second beam passes through the phase delay unit 50 and then is phase delayed again by the reflection mirror 90 . It is directed toward the ruler (50). A phase delay is generated while passing through the phase delay unit 50, and the second beam reflected by the reflection mirror 90 at the rear end of the phase delay unit 50 is again transferred to the phase delay unit 50 and the first polarizer ( After passing through 20), it enters the photodetector 60 through the light splitter 30 .

The first polarizer 20 functions as a polarization generator that generates polarized light when the second beam is split from the light splitter 30 and travels toward the phase delay unit 50, and the second beam is the reflection mirror ( 90), it functions as a polarization analyzer when it passes through the first polarizer 20 again while being reflected back.

As described above, according to the present embodiment, the first path along which the first beam travels proceeds to the sample 100, is reflected, and then proceeds to the photodetector 60 through the light splitter 30, as shown in FIG. There is a similar aspect to the first path according to the embodiment of the. In addition, according to the present embodiment, the second beam is polarized from the light splitter 30 through the first polarizer 20 , passes through the phase retarder 50 , is reflected by the reflection mirror 90 , and is again reflected to the first The second path proceeding to the photodetector 60 by sequentially passing through the polarizer 20 and the light splitter 30 is polarized before passing through the phase retarder 50, and has passed through the phase retarder 50. After passing through the polarizer once more to analyze the polarized light, there is a similar aspect to the second path of FIG. 2 in that it proceeds to the photodetector 60 . Meanwhile, the first polarizer 20 and the light splitter 30 may be integrated and implemented by a polarizing beam splitter that simultaneously polarizes and splits the light source.

According to the embodiment of FIG. 6 , the reflectivity information is extracted from the low frequency signal of the first beam, and the incident light amount information is extracted after modulating the second beam to a high frequency through the phase delay unit 50, and the reflectivity and In that the amount of incident light can be acquired at once in real time, the action or effect of FIG. 2 can be provided as it is.

Meanwhile, as shown in FIG. 7 , the reflectance and incident light quantity measuring apparatus according to another aspect of the present invention includes a light source 10 , a first beam directed to the sample, and a second beam separated from the first beam. A light splitter 30 for splitting into two beams, a phase retarder 50 for delaying the phase of the first beam split by the splitter, and a reflected beam reflected by the sample 100 and the first beam , a photodetector 60 for detecting the second beam, a first polarizer 20 disposed between the sample 100 and the photodetector 60 , and a signal detected by the photodetector 60 at a low frequency and a signal processing unit 80 for obtaining a signal by separating a signal and a high-frequency signal, and obtaining a reflectivity and an incident light amount of the sample 100 from the low-frequency signal and the high-frequency signal.

In the embodiment according to Fig. 7, the same reference numerals are given to components that perform the same operations as those of Fig. 2, and detailed descriptions thereof are omitted. 7, the light source 10, the light splitter 30, the objective lens 40, the first polarizer 20, the phase retarder 50, the second polarizer 70, the photodetector ( 60) and the signal processing unit 80 are substantially the same in terms of configuration and operation according to the embodiment of FIG. 2 . As the phase delay unit 50, a multi-order phase delay unit 50 is also used as shown in FIG.

However, according to the embodiment of FIG. 7 , the positions of the phase retarder 50 and the first polarizer 20 are disposed between the sample 100 and the photodetector 60 to modulate the frequency of the amount of reflected light. Accordingly, the light splitter 30 splits the light source 10 into a first beam and a second beam, and a phase delay occurs while the first beam passes through the phase delay unit 50 . The first beam passing through the reflection of the phase retarder 50 and the sample 100 is configured to enter the photodetector 60 .

The first polarizer 20 functions as a polarization generator that generates polarized light when the first beam split from the light splitter 30 travels toward the phase retarder 50, and the first beam is transmitted to the sample ( When it is reflected back from 100) and passes through the first polarizer 20 again, it functions as a polarization analyzer. Meanwhile, the first polarizer 20 and the light splitter 30 may be integrated and implemented by a polarizing beam splitter that simultaneously polarizes and splits the light source.

The first polarizer 20 functions as a polarization generator that generates polarized light when the second beam is split from the light splitter 30 and travels toward the phase delay unit 50, and the second beam is the phase delay unit After passing through (50), the second polarizer 70 passing through when entering the photodetector 60 functions as a polarization analyzer for polarization analysis of the second beam.

The first beam reflected from the sample 100 and returned may be configured to pass through the optical splitter 30 and enter the photodetector 60 using an additional optical path converting means. For example, as shown in FIG. 7 , the first beam passing through the light splitter 30 may use a plurality of mirrors 110 to configure an optical system so that the first beam flows into the photodetector 60 . . Of course, the manner in which the first beam enters the photodetector 60 is not limited to the manner in FIG. 7 .

As described above, according to the present embodiment, the first beam is polarized through the first polarizer 20, passes through the phase retarder 50, passes through the first polarizer 20 for polarization analysis, and then passes through the photodetector ( The first path going to 60) is polarized before passing through the phase retarder 50, and after passing through the phase retarder 50, passes through the polarizer once more to interpret the polarized light and then passes through the photodetector 60 ) is similar to the second path of FIG.

In addition, the second path proceeding according to the present embodiment is similar to the first path according to the embodiment of FIG. 2 in that it advances the information of the incident light amount to the photodetector 60 through the light splitter 30 . There is this.

According to the embodiment of Fig. 7, information on the amount of incident light is extracted from the low-frequency signal of the second beam, and information on reflectivity is extracted after modulating the first beam to a high frequency through the phase retarder 50, and the reflectivity and incidence In that the amount of light can be acquired at once in real time, the action or effect of FIG. 2 can be provided as it is.

As such, the apparatus for measuring reflectance and incident light according to an embodiment of the present invention can simultaneously acquire the incident light amount and reflectivity value in real time for every measurement without going through a separate process for measuring the incident light amount. The user can accurately calculate the thickness of the sample 100 by checking the amount of incident light in real time and accurately extracting the reflectivity value without a separate process of measuring the amount of incident light.

In the above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications may be provided without departing from the scope of the present invention.

10... light source 20... first polarizer
30... Splitter 40... Objective
50... Phase delay 60... Photodetector
70... Second polarizer 80... Signal processing unit
90... reflective mirror 100... sample

Claims (9)

light source;
a light splitter for splitting the light source into a first beam directed toward the sample and a second beam separated from the first beam;
a phase delayer for delaying the phase of the second beam divided by the optical splitter;
a photodetector configured to detect the reflected beam from which the first beam is reflected by the sample and the second beam that has passed through the phase retarder;
a first polarizer disposed between the light source and the phase retarder;
a second polarizer disposed between the phase retarder and the photodetector; and
A signal processing unit for obtaining a signal by separating a signal detected by the photodetector from a low-frequency signal and a high-frequency signal, and obtaining a reflectance and an incident light amount of the sample from the low-frequency signal and the high-frequency signal; A device for measuring the amount of incident light. According to claim 1,
The phase retarder is an apparatus for measuring reflectance and incident light, characterized in that it is a multi-order retarder. According to claim 1,
and the first polarizer and the light splitter are integrated into a polarization beam splitter that simultaneously polarizes and splits the light source. light source;
a light splitter for splitting the light source into a first beam directed toward the sample and a second beam separated from the first beam;
a phase delayer for delaying the phase of the second beam divided by the optical splitter;
a reflective mirror disposed at the rear end of the phase delay unit to reflect the second beam passing through the phase delay unit and to proceed to the phase delay unit again;
a photodetector configured to detect the reflected beam of the first beam reflected by the sample and the second beam passing through the phase delay unit;
a first polarizer disposed between the light source and the reflective mirror; and
A signal processing unit for obtaining a signal by separating a signal detected by the photodetector from a low-frequency signal and a high-frequency signal, and obtaining a reflectance and an incident light amount of the sample from the low-frequency signal and the high-frequency signal; A device for measuring the amount of incident light. 5. The method of claim 4,
The phase retarder is an apparatus for measuring reflectance and incident light, characterized in that it is a multi-order retarder. 5. The method of claim 4,
and the first polarizer and the light splitter are integrated into a polarization beam splitter that simultaneously polarizes and splits the light source. light source;
a light splitter for splitting the light source into a first beam directed toward the sample and a second beam separated from the first beam;
a phase retarder for delaying the phase of the first beam divided by the optical splitter;
a photodetector configured to detect a reflected beam from which the first beam is reflected by the sample and the second beam having incident light amount information;
a first polarizer disposed between the sample and the photodetector; and
A signal processing unit for obtaining a signal by separating a signal detected by the photodetector from a low-frequency signal and a high-frequency signal, and obtaining a reflectance and an incident light amount of the sample from the low-frequency signal and the high-frequency signal; A device for measuring the amount of incident light. 8. The method of claim 7,
The phase retarder is an apparatus for measuring reflectance and incident light, characterized in that it is a multi-order retarder. 8. The method of claim 7,
and the first polarizer and the light splitter are integrated into a polarization beam splitter that simultaneously polarizes and splits the light source.

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