Multilayer refraction sample detection device and method

Abstract

The invention belongs to the field of sample morphology detection, and particularly discloses a multilayer refraction sample detection device and method. The method comprises the following steps: dividing an initial light beam into a first light beam and a second light beam, then decomposing the first light beam into two paths of reference light with an orthogonal polarization state and a fixed optical path difference, and transmitting the second light beam to a sample to be measured to generate a plurality of reflected light; and collecting an initial interference spectrum generated by interference of the reference light and the reflected light, removing inherent artifacts introduced by the reference arm, and self-correlation artifacts and mirror image artifacts in the to-be-detected sample from the initial interference spectrum, obtaining an artifact-free interference spectrum, and further obtaining three-dimensional information of the to-be-detected sample. The inner layer structure of the multi-layer refraction sample can be accurately measured under the condition that the sample to be measured is not damaged.

Description

Technical Field

[0001] The present application belongs to the field of sample morphology detection, and more specifically, to a multi-layer refractive sample detection device and method. Background Art

[0002] The tomography of multi-layer refractive samples involves many fields such as medical imaging, industrial production inspection, and optical component assembly inspection. However, due to the particularity of the structure of multi-layer refractive samples, there is currently no mature and reliable non-destructive tomography solution. Taking the display field as an example, during the manufacturing process, the LCD panel may be defective or damaged due to defects in the raw materials and industrial liquid resin. Industrial liquid resins will produce defects due to fine dirt (dust particles) or impurities, and the liquid resin between the inner layers of the LCD panel is not fully cured. During the packaging process, the upper substrate will also produce defects after the color filter (CF) deposition and alignment layer friction process. Reliable inspection equipment can detect and analyze defects and possible causes in the LCD manufacturing process to minimize production line downtime. Traditional inspection technologies include visual inspection methods, machine vision inspection, and electronic inspection, but these technologies can only provide two-dimensional inspection information, and it is difficult to obtain three-dimensional information about defects in sub-layers. In addition, lens modules also face the same inspection challenges. Existing inspection technologies can only measure single lenses and cannot provide three-dimensional morphology after assembly to evaluate errors such as lens spacing and eccentricity, making it difficult to provide guarantee for the yield of the lens group. Although the spectral domain interferometry method can achieve non-destructive tomography, it has inherent artifacts when imaging multi-layer samples. In addition, the spectral domain interferometry method has a limited range and cannot measure display panels with thicker thickness. Summary of the invention

[0003] In view of the defects of the prior art, the purpose of the present application is to provide a multi-layer refractive sample detection device and method, aiming to solve the problems of limited measurement range and complex artifact interference when detecting multi-layer refractive samples.

[0004] To achieve the above-mentioned purpose, in a first aspect, the present application provides a multi-layer refractive sample detection device, comprising: a data processing system and a spectral domain interferometry imaging system; the spectral domain interferometry imaging system comprises a wide-spectrum coherent light source, a reference arm, a measurement probe, a fiber coupler and a spectrometer; The first end of the optical fiber coupler is connected to a broadband light source, the second end thereof is connected to a spectrometer, the third end thereof is connected to a reference arm, and the fourth end thereof is connected to a measuring probe; during detection, the sample to be tested is located below the measuring probe; and the data processing system is connected to the spectrometer; The wide spectrum coherent light source is used to output an initial light beam and transmit it to a fiber coupler; the fiber coupler is used to split the initial light beam into a first light beam and a second light beam, and transmit the first light beam to a reference arm and transmit the second light beam to a measurement probe; The reference arm is used to decompose the first light beam into two reference lights with orthogonal polarization states and fixed optical path difference; the optical fiber coupler is used to return the two reference lights to the spectrometer; The measuring probe is used to transmit the second light beam to the sample to be measured, and generate a reflected light on each surface of the sample to be measured; the optical fiber coupler is used to transmit the reflected light to the spectrometer; The spectrometer is used to collect the interference spectrum generated by the reflected light and the reference light; The data processing system is used to remove the inherent artifacts introduced by the reference arm, the autocorrelation artifacts inside the sample to be tested, and the mirror artifacts in the initial interference spectrum transmitted by the spectrometer, so as to obtain an artifact-free interference spectrum; Wherein, the sample to be tested is a multi-layer refractive sample.

[0005] Further preferably, the multi-layer refractive sample includes a display panel, a biological tissue and a lens module.

[0006] Further preferably, the measuring probe comprises a first optical fiber collimator, a two-dimensional galvanometer and a scanning lens; The optical fiber collimator is used to collimate the second light beam; the two-dimensional galvanometer is used to deflect the collimated second light beam; and the scanning lens is used to focus the deflected second light beam.

[0007] Further preferably, the reference arm comprises: a second optical fiber collimator, a crystal, a focusing lens and a reflector arranged in sequence; The second optical fiber collimator is used to collimate the first light beam; the crystal is used to generate two reference lights with orthogonal polarization states and fixed optical path difference; the focusing lens and the reflector are used to focus and reflect the two reference lights respectively.

[0008] In a second aspect, the present application provides a multi-layer refractive sample detection method, comprising the following steps: Step 1: Split the initial light beam into a first light beam and a second light beam, then decompose the first light beam into two reference lights with orthogonal polarization states and a fixed optical path difference, and transmit the second light beam to the sample to be tested to generate a number of reflected lights; Step 2: Collect the initial interference spectrum generated by the interference of the reference light and the reflected light, remove the inherent artifacts introduced by the reference arm, the autocorrelation artifacts inside the sample to be tested, and the mirror artifacts in the initial interference spectrum, and obtain an artifact-free interference spectrum; Step 3: Obtain three-dimensional information of the sample to be tested based on the artifact-free interference spectrum.

[0009] Further preferably, the method for removing the autocorrelation artifacts inside the sample to be tested in the initial interference spectrum specifically comprises the following steps: The interference spectrum generated by the interference of the reference light is removed from the initial interference spectrum, and then a first interference spectrum in the frequency domain is obtained by Fourier transform; Phase shift of the first interference spectrum Then perform Fourier transform to obtain the second interference spectrum; and at the same time phase shift the first interference spectrum Then perform Fourier transform to obtain the third interference spectrum; Sum the second interference spectrum and the third interference spectrum and take their absolute values ​​to obtain a spectrum sum; Difference is calculated between the second interference spectrum and the third interference spectrum, and the absolute value is taken to obtain a spectrum difference; Then, the spectrum sum and the spectrum difference are subtracted and the absolute value is taken to obtain a reconstructed signal with the autocorrelation artifacts inside the sample to be tested removed; in, is the phase difference between the reference light.

[0010] Further preferably, the method for removing the mirror image artifact in the initial interference spectrum specifically comprises the following steps: Use a given threshold to find the peak in the negative half axis of the reconstructed signal and record the peak position ; In the second interference spectrum, according to the peak position as well as , find the amplitude and The signal peak of when When , the amplitude extracted from the reconstructed signal is The signal peak of ; otherwise, the amplitude is extracted from the reconstructed signal The signal peak of The image artifacts are eliminated to obtain artifact-free interference spectrum.

[0011] Further preferably, the optical path difference of the two reference lights introduced by the crystal in the reference arm is:

[0012] in, They are the ordinary refractive index and the extraordinary refractive index of the crystal respectively; is the central wave number, is the crystal thickness.

[0013] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the prior art: The present application provides a multi-layer refractive sample detection method, which belongs to the field of spectral domain interferometric imaging. The crystal in the reference arm is used to generate two reference lights with orthogonal polarization states and a fixed optical path difference. Based on this, the inherent artifacts introduced by the reference arm, the autocorrelation artifacts inside the sample to be tested, and the mirror artifacts are removed from the interference spectrum transmitted by the spectrometer, and an artifact-free interference spectrum can be obtained. Therefore, the present application can accurately measure the inner structure of the multi-layer refractive sample without damaging the sample to be tested.

[0014] The existing mainstream artifact removal method is based on phase modulation technology of devices such as piezoelectric translation stages. This type of technology requires an active phase shift device, a more complex system structure, and higher requirements for phase stability. In comparison, the solution proposed in this application has a simpler structure, a more compact system, no additional volume is required, stronger shock resistance, lower cost, and no need to sacrifice measurement speed. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of a multi-layer refractive sample detection device provided in an embodiment of the present application; Figure 2 is a schematic diagram of the internal structure of the measuring probe provided in an embodiment of the present application; Figure 3 is a schematic diagram of the internal structure of a reference arm provided in an embodiment of the present application; FIG4(a) is a simulation of the signal transformation spectrum at 1000 μm provided in an embodiment of the present application. , ); FIG4( b ) is a simulation of the signal transformation spectrum at 100 μm provided in an embodiment of the present application ( , ); FIG4( c ) is a simulation of the signal transformation spectrum at -1000 μm provided in an embodiment of the present application ( , ); FIG4(d) is a simulation of the signal transformation spectrum at -100 μm provided in an embodiment of the present application ( , ); Figure 5 This is a schematic diagram of the principle of polarization multiplexing to remove autocorrelation artifacts provided in an embodiment of the present application; Figure 6 is a schematic diagram of the principle of removing mirroring artifacts provided in an embodiment of the present application; Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein: 1 is a broadband light source; 2 is a spectrometer; 3 is a computer; 4 is a fiber coupler; 5 is a bracket; 6 is a measuring probe; 7 is a sample to be measured; and 8 is a reference arm. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0017] The terms “first”, “second” and the like in the specification and claims herein are used to distinguish different objects rather than to describe a specific order of the objects.

[0018] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0019] In the description of the embodiments of the present application, unless otherwise specified, “plurality” means two or more than two.

[0020] First, the technical terms involved in the embodiments of the present application are introduced.

[0021] Multilayer refractive samples include but are not limited to display panels, biological tissues and lens modules. Among them, display panels are a typical multilayer refractive sample; Spectral domain interferometry imaging is a non-contact measurement method based on broadband light interference imaging. Since it is a non-contact measurement, it will not cause damage to the sample. In addition, this technology has the characteristics of tomography, so it can realize the measurement of the inner structure of multi-layer refractive samples. In order to solve the problems of existing display panel inspection methods, such as the inability to detect interlayer defects, limited measurement range, and artifact interference, the present application provides a multi-layer refractive sample inspection method based on spectral domain interferometry imaging, which is used to detect the three-dimensional morphology and interlayer defects of the display panel, thereby improving the yield of the production line.

[0022] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0023] Figure 1The present invention is a schematic diagram of a multi-layer refractive sample detection device provided by an embodiment of the present application, wherein the device comprises: a spectral domain interferometric imaging system and a computer; the spectral domain interferometric imaging system comprises a wide-spectrum coherent light source, a reference arm, a measuring probe, a fiber coupler and a spectrometer; wherein the reference arm is coupled with an optical fiber input, and comprises an optical fiber collimator, a crystal, a focusing lens and a reflector; the measuring probe is coupled with an optical fiber input, and comprises: an optical fiber collimator, a two-dimensional galvanometer and a scanning lens; when the multi-layer refractive sample detection device is measuring, one output end of the optical fiber coupler is connected to the measuring probe, and the other output end is connected to the reference arm; The display panel to be tested is placed on the sample table, and the measuring probe is fixed by a bracket; When measuring, press Figure 1 The device is set up as shown, the light emitted by the wide spectrum light source 3 is divided into two paths through the optical fiber coupler 4, one path is transmitted to the reference arm, and the other path is transmitted to the measuring probe 6; the light beam transmitted to the reference arm is collimated by the collimator, and is decomposed into two orthogonal polarized lights with phase difference when passing through the crystal, and then focused on the reflector, and a part of the light after the reflected light returns to the optical fiber Incoming spectrometer 2; Further preferably, the measuring probe 6 has a structure as follows Figure 2 As shown, the light transmitted to the measuring probe is collimated by the fiber collimator, the two-dimensional galvanometer deflects the light beam, and the scanning lens focuses the light beam; The reference arm structure is as follows Figure 3 As shown, it includes: a fiber collimator, a focusing lens, a crystal and a reflector; the function of the crystal is to generate two reference lights with orthogonal polarization states and a fixed optical path difference, and the devices that achieve the same function include but are not limited to polarization-maintaining optical fibers; The light transmitted to the measuring probe is collimated by the fiber collimator, the two-dimensional galvanometer deflects the light beam, and the scanning lens focuses the light beam. The focused light enters the lens group, and each layer of the surface of the sample to be measured will produce a reflected light. After the reflected light returns to the optical fiber, part of the light is transmitted to the spectrometer 2; the two paths of light transmitted to the spectrometer interfere with each other, and the spectrometer will collect interference fringes. The spectrum of the reflected light from the reference arm can be obtained by using a computer to perform Fourier transform and other data processing algorithms on the spectrum data. and the reflected light spectrum from the sample to be tested Spatial reflection information ; Use the galvanometer to scan the sample to be tested, and you can get the spatial reflection information of the entire sample to be tested ,right Peak value extraction is performed to finally obtain the three-dimensional information of the entire sample to be tested.

[0024] The following describes the spectral interferometry principle of polarization multiplexing artifact suppression For multi-layer samples, the light returning from the sample includes reflections from the internal interfaces. Without loss of generality, it is assumed that the reflection coefficient of each layer of the sample is r , then form The sample light field of a layer-refractive object can be expressed as:

[0025] in, , represents a reflector; , represents the illumination light field with 45° polarization incident, is the amplitude factor, is the wave number, It is located in j The optical path difference of the layer relative to the reference surface; The Jones matrix of the reference beam is described as:

[0026] in, , represents a birefringent filter, represents the birefringence phase difference; The ordinary and extraordinary refractive indices are: is the crystal thickness; The interference spectrum has the following form:

[0027] in, is the light source power spectral density, and , is the optical path difference of the orthogonal polarization states of the birefringent crystal, and ; Recording the reference arm spectrum , which is removed as the background, and the interference spectrum is obtained to suppress the inherent artifacts introduced by the reference arm into the system:

[0028] in, for ; In order to ensure the symmetry of the reconstructed signal in the spatial domain, the phase shift Then Fourier transform:

[0029] right Phase Shift Then Fourier transform:

[0030] Sum and take the absolute value:

[0031] Find the difference and take the absolute value:

[0032] The reconstructed signal after removing the autocorrelation artifacts inside the sample to be tested is:

[0033] in, express Fourier transform of the signal; reconstruct the signal Only the signal and mirror artifacts symmetrical about zero optical path length are included, and the autocorrelation artifacts are eliminated; In order to achieve the resolution of the signal and the image, the fast axis of the crystal is deflected , so that the intensities of the two orthogonally polarized reference lights are unequal, then the reference field can be written as:

[0034] Under this condition, the interference spectrum after subtracting the reference light is:

[0035] For a certain interface j , and its two orthogonal polarization cross-correlation signals are , , the ratio of their signal strengths is defined as ,when , , according to the intensity and , and because is a positive number, then the signal in Fourier space Always On the right side, Figure 4 (a) to Figure 4 (d) show the , The transformation spectrum simulation is shown when the real signal is 1000um, 100um, -1000um, and -100 um respectively. Based on this feature, the real signal and the mirror image artifact can be distinguished.

[0036] It should be pointed out here that the above is to explain the principle of spectral interferometry with polarization multiplexing artifact suppression. First, the interference spectrum generated by the reference light and the reflected light is introduced to remove the inherent artifacts introduced by the reference arm and the autocorrelation artifacts of the sample to be measured. Then, it is introduced how to remove the mirror artifacts when the crystal fast axis is deflected. In practical applications, the crystal fast axis is first deflected. , when the intensities of the two orthogonally polarized reference lights are unequal, the inherent artifacts introduced by the reference arm, the autocorrelation artifacts of the sample to be measured, and the mirror artifacts are removed from the interference spectrum generated by the reference light and the reflected light.

[0037] According to the above theory, if Figure 5 and Figure 6As shown, the present application provides a polarization multiplexing method for removing autocorrelation artifacts and a method for removing mirroring artifacts, which specifically include the following steps: Step S1: Remove autocorrelation artifacts Step S1.1: Remove the background and collect the interference spectrum and reference spectrum Subtract and then obtain it through Fourier transform ; Step S1.2: Frequency Shift After getting ; Step S1.3: Frequency Shift After getting ; Step S1.4: and Sum and take the absolute value to get ; Step S1.5: and Find the difference and take the absolute value ; Step S1.6: and Calculate the difference and take the absolute value to obtain the reconstructed signal without autocorrelation artifacts .

[0038] Step S2: Remove mirror artifacts Step S2.1: Use the given threshold to find the peak in the negative semi-axis and record the peak position ; Step S2.2: According to the coordinates , Find the peak , ; Step S2.3: If , then in Extract all true signals from , remove mirror artifacts On the contrary, Extract all real signals from , remove mirror artifacts , get full range signal without artifacts .

[0039] Crystal Design The choice of crystal thickness requires Greater than the point spread function of the spectral domain interference system; the point spread function of the system in this application is 11 , taking quartz crystal as an example, set , at 840nm ; For the proposed system setup, the orthogonal polarization optical path difference introduced by the birefringent crystal can be written as:

[0040] in, They are the ordinary refractive index and the extraordinary refractive index of the crystal respectively; is the central wave number; is the crystal thickness; By increasing the crystal thickness Alternatively, choosing a crystal with a large birefringence index can increase the polarization-dependent optical path difference caused by birefringence.

[0041] In summary, compared with the prior art, the present application has the following advantages: The present application provides a method for detecting a multilayer refractive sample, which belongs to the field of spectral domain interference imaging. The crystal in the reference arm is used to generate two reference lights with orthogonal polarization states and fixed optical path difference. Based on this, the inherent artifacts introduced by the reference arm, the autocorrelation artifacts inside the sample to be tested, and the mirror artifacts are removed from the interference spectrum transmitted by the spectrometer, and an artifact-free interference spectrum can be obtained. Therefore, the inner structure of the multilayer refractive sample can be accurately measured without damaging the sample to be tested. The existing mainstream artifact removal method is based on the phase modulation technology of equipment such as piezoelectric displacement stages. This type of technology needs to be equipped with active phase shifting equipment, the system structure is more complex, and the phase stability requirements are higher. In comparison, the solution proposed in the present application has a simpler structure, a more compact system, no additional volume is required, stronger shock resistance, lower cost, and no need to sacrifice measurement speed.

[0042] It should be understood that expressions such as "including" and "may include" that may be used in the present application indicate the existence of the disclosed functions, operations, or constituent elements, and do not limit one or more additional functions, operations, and constituent elements. In the present application, terms such as "including" and / or "having" may be interpreted as indicating specific characteristics, numbers, operations, constituent elements, components, or combinations thereof, but may not be interpreted as excluding the existence or possibility of adding one or more other characteristics, numbers, operations, constituent elements, components, or combinations thereof.

[0043] In addition, in the present application, the expression "and / or" includes any and all combinations of the associated listed words. For example, the expression "A and / or B" may include A, may include B, or may include both A and B.

[0044] In the description of the embodiments of the present application, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense.

[0045] In addition, in the embodiments of the present application, the mathematical concepts mentioned are symmetry, equality, parallelism, verticality, etc. These limitations are all for the current state of the art, rather than being absolutely strict definitions in a mathematical sense, and allow a small amount of deviation, approximation to symmetry, approximation to equality, approximation to parallelism, approximation to verticality, etc. are all possible. For example, A and B are parallel, which means that A and B are parallel or approximately parallel, and the angle between A and B can be between 0 and 10 degrees. A and B are perpendicular, which means that A and B are perpendicular or approximately perpendicular, and the angle between A and B can be between 80 and 100 degrees.

[0046] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art who is familiar with the present technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A multi-layer refraction sample detection device, characterized in that: include: Data processing system and spectral domain interferometry imaging system; The spectral domain interferometric imaging system includes a wide spectrum coherent light source, a reference arm, a measurement probe, a fiber coupler and a spectrometer; The first end of the optical fiber coupler is connected to a broadband light source, the second end thereof is connected to a spectrometer, the third end thereof is connected to a reference arm, and the fourth end thereof is connected to a measuring probe; during detection, the sample to be tested is located below the measuring probe; and the data processing system is connected to the spectrometer; The wide spectrum coherent light source is used to output an initial light beam and transmit it to a fiber coupler; the fiber coupler is used to split the initial light beam into a first light beam and a second light beam, and transmit the first light beam to a reference arm and transmit the second light beam to a measurement probe; The reference arm is used to decompose the first light beam into two reference lights with orthogonal polarization states and fixed optical path difference; the optical fiber coupler is used to return the two reference lights to the spectrometer; The measuring probe is used to transmit the second light beam to the sample to be measured, and a reflected light is generated on each surface of the sample to be measured. The optical fiber coupler is used to transmit the reflected light to the spectrometer. The spectrometer is used to collect the initial interference spectrum generated by the reflected light and the reference light; The data processing system is used to remove the inherent artifacts introduced by the reference arm, the autocorrelation artifacts inside the sample to be tested, and the mirror artifacts in the initial interference spectrum transmitted by the spectrometer, so as to obtain an artifact-free interference spectrum; Wherein, the sample to be tested is a multi-layer refractive sample.

2. The multi-layer refraction sample detection device according to claim 1, characterized in that: Multilayer refractive samples include display panels, biological tissues, and lens modules.

3. The multi-layer refraction sample detection device according to claim 1, characterized in that: The measuring probe comprises a first optical fiber collimator, a two-dimensional galvanometer and a scanning lens; The optical fiber collimator is used to collimate the second light beam; the two-dimensional galvanometer is used to deflect the collimated second light beam; and the scanning lens is used to focus the deflected second light beam.

4. The multi-layer refraction sample detection device according to claim 1 or 3, characterized in that: The reference arm includes: A second optical fiber collimator, a crystal, a focusing lens and a reflector are arranged in sequence; The second optical fiber collimator is used to collimate the first light beam; The crystal is used to generate two reference lights with orthogonal polarization states and fixed optical path difference; the focusing lens and the reflecting mirror are used to focus and reflect the two reference lights respectively.

5. A multi-layer refraction sample detection method based on the multi-layer refraction sample detection device according to any one of claims 1 to 4, characterized in that: The following steps are involved: Step 1: Split the initial light beam into a first light beam and a second light beam, then decompose the first light beam into two reference lights with orthogonal polarization states and a fixed optical path difference, and transmit the second light beam to the sample to be tested to generate a number of reflected lights; Step 2: Collect the initial interference spectrum generated by the interference of the reference light and the reflected light, remove the inherent artifacts introduced by the reference arm, the autocorrelation artifacts inside the sample to be tested, and the mirror artifacts in the initial interference spectrum, and obtain an artifact-free interference spectrum; Step 3: Obtain three-dimensional information of the sample to be tested based on the artifact-free interference spectrum.

6. The multi-layer refraction sample detection method according to claim 5, characterized in that: The method for removing the autocorrelation artifact inside the sample to be measured in the initial interference spectrum specifically comprises the following steps: The interference spectrum generated by the interference of the reference light is removed from the initial interference spectrum, and then a first interference spectrum in the frequency domain is obtained by Fourier transform; Phase shift of the first interference spectrum Then perform Fourier transform to obtain the second interference spectrum; and at the same time phase shift the first interference spectrum Then perform Fourier transform to obtain the third interference spectrum; Sum the second interference spectrum and the third interference spectrum and take their absolute values ​​to obtain a spectrum sum; Difference is calculated between the second interference spectrum and the third interference spectrum, and the absolute value is taken to obtain a spectrum difference; Then, the spectrum sum and the spectrum difference are subtracted and the absolute value is taken to obtain a reconstructed signal with the autocorrelation artifacts inside the sample to be tested removed; in, is the phase difference between the reference light.

7. The multi-layer refraction sample detection method according to claim 6, characterized in that: The method for removing the image artifact in the initial interference spectrum comprises the following steps: Use a given threshold to find the peak in the negative half axis of the reconstructed signal and record the peak position ; In the second interference spectrum, according to the peak position as well as , find the amplitude and The signal peak of when When , the amplitude extracted from the reconstructed signal is The signal peak of ; otherwise, the amplitude is extracted from the reconstructed signal The signal peak of The image artifacts are eliminated to obtain artifact-free interference spectrum.

8. The multi-layer refraction sample detection method according to claim 5, characterized in that: The optical path difference of the two reference lights introduced by the crystal in the reference arm is: in, They are the ordinary and extraordinary refractive indices of the crystal, is the central wave number; is the crystal thickness.

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