A method for detecting optical properties of multilayer thin films based on the combination of transmission Goos-Hanchen shift and spectroscopy

Abstract

A method for detecting the optical properties of a multilayer thin film based on the combination of transmission Goos-Hanchen shift and spectrum, characterized by comprising: S1: measuring the position information of a light spot of a TM polarized wave transmitted through the multilayer thin film; S2: obtaining an incident wavelength-transmission Goos-Hanchen shift relationship curve through data processing; S3: measuring the spectral information of the multilayer thin film; S4: determining the type of the multilayer thin film: if it is an anti-reflection film, proceed to S5; if it is an anti-reflection film, proceed to S6; if it is a beam splitter film, proceed to S7; S5: establishing an anti-reflection film target function, and calculating the anti-reflection film parameter vector when the anti-reflection film target function is minimized; S6: establishing an anti-reflection film target function, and calculating the anti-reflection film parameter vector when the anti-reflection film target function is minimized; S7: establishing a beam splitter film target function, and calculating the beam splitter film parameter vector when the beam splitter film target function is minimized; effect: improving the measurement efficiency and accuracy of the optical properties of the multilayer thin film.

Description

Technical Field

[0001] The present invention relates to the technical field of material analysis and measurement, and in particular to a method for detecting optical properties of multilayer thin films based on the combination of transmission Goos-Hanchen shift and spectroscopy. Background Art

[0002] With the widespread application of nanoscale thin films in microelectronics, optoelectronics, aerospace, medical instruments, and polymer materials, thin film technology has become a hot topic in current scientific research and industrial production. The continuous improvement and rapid development of thin film technology have also placed higher demands on various film parameters. For example, the optical constants and thickness of thin films play a decisive role in their optical, mechanical, and electromagnetic properties. Optical thin films are categorized as anti-reflection films, anti-reflection films, and spectroscopic films. In practical applications, multiple layers of thin films are often stacked to enhance the film's reflective, transmittance, and spectroscopic properties. Therefore, the simultaneous and precise measurement of the optical constants of nanoscale multilayer thin films has become a crucial technology.

[0003] Disadvantages of Existing Technologies: Currently, most existing technologies use ellipsometry or photometry to obtain thin film characteristic parameters. However, ellipsometry suffers from the problem of film thickness periodicity, which results in multiple solutions for film thickness, thus affecting the calculation of optical constants. Photometry, on the other hand, is susceptible to environmental influences, resulting in inaccurate results. Furthermore, both photometry and ellipsometry have certain drawbacks for different functional films. Summary of the Invention

[0004] The present invention provides a method for detecting the optical properties of multilayer thin films based on the combination of transmission Goos-Hanchen shift and spectroscopy, which improves the measurement efficiency and accuracy of the optical properties of multilayer thin films.

[0005] To achieve the above-mentioned object, the present invention provides a method for detecting the optical properties of multilayer thin films based on the combination of transmission Goos-Hanchen shift and spectroscopy, the key of which is to include the following steps:

[0006] Step S1: measuring the position information of the light spot of the TM polarized wave transmitted through the multilayer film: using a transmission Goos-Hanchen shift measuring device to measure the position information of the light spot of the TM polarized wave transmitted through the multilayer film;

[0007] Step S2: Data processing to obtain an incident wavelength-transmission Gous-Hanchen shift relationship curve: Based on the light spot position information, the incident wavelength-transmission Gous-Hanchen shift relationship curve of the multilayer film is obtained, and then the transmission Gous-Hanchen shift under TM polarization is obtained;

[0008] Step S3: measuring spectral information of the multilayer film: using a spectral measurement device to measure the reflection spectrum data and transmission spectrum data of the TM polarized wave and the TE polarized wave of the multilayer film at a continuous wavelength λ, while keeping the incident angle and the incident point unchanged during the measurement process;

[0009] Step S4: Determine the type of the multilayer film: determine the film type of the multilayer film according to the measured reflection spectrum data and transmission spectrum data;

[0010] When the average reflectivity within the incident wavelength is greater than or equal to 0.95, the film type of the multilayer film is an anti-reflection film, and the process proceeds to step S5;

[0011] When the average transmittance within the incident wavelength is greater than or equal to 0.95, the film type of the multilayer film is an antireflection film, and the process proceeds to step S6;

[0012] When the average transmittance and the average reflectance within the incident wavelength are both 0.5±0.05, the film type of the multilayer film is a beam splitter film, and the process proceeds to step S7;

[0013] Step S5: When the multilayer film is determined to be an anti-reflection film, the transmitted Goos-Hanchen shift and the TM polarized wave reflection spectrum data are normalized to obtain reflectivity values ​​and transmitted Goos-Hanchen shift data sets of the same magnitude, and an anti-reflection film target function is established to calculate the optical constants of the anti-reflection film across the entire wavelength range.

[0014] Initialize the search range of the solution space {n, k, d}, use fitting calculation, judge the accuracy of the solution according to the size of the anti-reflection film target function, and obtain the anti-reflection film parameter vector a1 of the multilayer thin film when the anti-reflection film target function is minimized;

[0015] Step S6: When the multilayer film is determined to be an antireflection film, the transmission Gous-Hanchen shift and the transmission spectrum data of the TM polarized wave are normalized to obtain a data set of transmittance values ​​and transmission Gous-Hanchen shift values ​​of the same magnitude, and an antireflection film target function is established to calculate the optical constants of the antireflection film across the entire wavelength range.

[0016] Initializing the search range of the solution space {n, k, d}, using fitting calculation, judging the accuracy of the solution according to the magnitude of the antireflection film objective function, and obtaining the antireflection film parameter vector a2 of the multilayer thin film when the antireflection film objective function is minimized;

[0017] Step S7: When the multilayer film is determined to be a beamsplitter film, the transmitted Goos-Hanchen shift and the reflectance spectrum data of the TM polarized wave and the TE polarized wave are normalized to obtain reflectivity values ​​and transmitted Goos-Hanchen shift data sets of the same magnitude, establish a beamsplitter film target function, and calculate the optical constants of the beamsplitter film over the entire wavelength range;

[0018] Initialize the search range of the solution space {n, k, d}, use fitting calculation, judge the accuracy of the solution according to the size of the beam splitter objective function, and obtain the beam splitter parameter vector a3 of the multilayer film when the beam splitter objective function is minimized.

[0019] Through the above design, the film type is first preliminarily determined by collecting spectral information, and then the transmission Goos-Hanchen shift information of the multilayer film is collected. Combined with the corresponding spectral information, the optical constants of the multilayer film of the thin film sample under the continuous spectrum can be calculated, effectively solving the problem of quickly solving the multilayer film parameters.

[0020] Preferably, in step S1, when measuring with a transmission Goos-Hanchen shift measuring device, a three-phase thin film structure of substrate-multi-thin film layer-dielectric layer is used for detection; the multi-layer thin film is a multi-thin film layer plated on a substrate.

[0021] As an example: in step S2, the transmission Goos-Hanchen shift under the TM polarization wave Based on the transfer matrix method, the calculation expression is obtained by multiplying multiple matrices as follows:

[0022]

[0023] Where S represents the characteristic matrix of the multilayer thin film structure, λ represents the wavelength of the incident light, β represents the phase factor of the thin film layer; x represents the xth layer of the thin film, x∈[1,m]; q represents the optical transfer coefficient; ε represents the dielectric constant, and the real part of the dielectric constant ε real =n 2 -k 2 , the imaginary part of the dielectric constant ε imag =2nk, n represents the refractive index, k represents the extinction coefficient; i is the imaginary part, θ represents the incident angle;

[0024] For TM polarization waves, the optical transmission coefficient q of each layer in the multilayer film structure is f , transmission coefficient t TM , transmission phase Φ TM , reflection coefficient r TM and the transmitted Goos-Hanchen shift The calculation expressions are:

[0025]

[0026]

[0027] Among them, S 11 、S 12 、S 21 、S 22 Represents a vector in a 2*2 matrix, p represents the basis, k xrepresents the incident light wave vector of the xth film layer, φ t represents the transmission phase, d represents the film thickness, k0 represents the incident light wave vector of the 0th layer of film, t represents the transmission coefficient, q0 represents the admittance of the incident interface, q N represents the admittance of the exit interface.

[0028] Preferably, in step S5, the objective function of the anti-reflection film is expressed as follows:

[0029]

[0030] Among them, F1 represents the target function of the anti-reflection film, N exp Indicates the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift under TM polarization wave obtained by inversion calculation; represents the transmitted Gous-Hanchen shift value of the i-th reference point under TM polarization wave extracted from the experimentally measured transmitted Gous-Hanchen shift curve; represents the reflectivity of the anti-reflection coating under TM polarization wave obtained by inversion calculation; represents the reflectivity of the anti-reflection film at the i-th reference point under the TM polarization wave extracted from the experimentally measured reflectivity curve; a1 represents the anti-reflection film parameter vector, a=(n1,k1,…nm,km), where m is the number of layers of the multilayer film, m≥2; n represents the refractive index, k represents the extinction coefficient, and d represents the film thickness; the subscript cal represents that obtained by inversion calculation, the subscript exp represents that obtained from experimental measurement, and the superscript TM represents the transverse magnetic wave.

[0031] Preferably, in step S6, the expression of the antireflection film objective function is as follows:

[0032]

[0033] Among them, F2 represents the target function of the antireflection film, N exp Indicates the total number of incident wavelengths;

[0034] represents the transmitted Goos-Hanchen shift under TM polarization wave obtained by inversion calculation; represents the transmitted Gous-Hanchen shift value of the i-th reference point under TM polarization wave extracted from the experimentally measured transmitted Gous-Hanchen shift curve; represents the transmittance of the AR coating under TM polarization wave obtained by inversion calculation; represents the transmittance of the AR coating at the i-th reference point under TM polarization wave extracted from the experimentally measured transmittance curve, and a2 represents the AR coating parameter vector.

[0035] As a preference: In formula (2), the transmittance of the antireflection film is The calculation expression is as follows:

[0036]

[0037] Preferably, in step S7, the beam splitter objective function is expressed as follows:

[0038]

[0039] Among them, F3 represents the beam splitter objective function, N exp Indicates the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift under TM polarization wave obtained by inversion calculation; represents the transmitted Gous-Hanchen shift value of the ith reference point under TM polarization extracted from the experimentally measured transmitted Gous-Hanchen shift curve; R 3_cal (i,a3) represents the reflectivity of the beam splitter film obtained by inversion calculation; R 3_exp (i) represents the reflectivity of the beamsplitter film at the i-th reference point extracted from the experimentally measured reflectivity curve, and a3 represents the beamsplitter film parameter vector.

[0040] As a preference: In formula (3), the calculation expression of the beam splitting film reflectivity R3 is as follows:

[0041]

[0042] in, represents the beam splitter reflection coefficient under TM polarization, represents the reflection coefficient of the beamsplitter film under TE polarization.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) Using incident light of continuous wavelength band for measurement, selecting the combined characterization mode of spectrum and transmission Goos-Hanchen shift, the optical constants of thin films at multiple wavelengths are solved simultaneously, avoiding the shortcomings of the existing photometric method in fitting reflectivity at multiple wavelengths, which introduces large imaginary errors of optical constants when analyzing and fitting thin film optical constants, thereby improving the solution accuracy;

[0045] (2) Improve the measurement method from two aspects: the transmission Goos-Hanchen shift measurement operation and algorithm calculation, and improve the measurement efficiency and accuracy;

[0046] (3) The present invention provides effective theoretical guidance and reference for solving the optical constants and thickness of multilayer films, and has the characteristics of good optimization effect and strong applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1This is a flow chart of the present invention for measuring parameters of multilayer thin films based on the combination of transmission Goos-Hanchen shift and spectroscopy;

[0048] Figure 2 is a schematic diagram of the prismatic thin film multilayer structure used in Example 1;

[0049] Figure 3 is a comparison chart of the wavelength-transmittance curve obtained in Example 1 and the curve obtained by calculation;

[0050] Figure 4 is a comparison diagram of the wavelength-transmission Goos-Hanchen shift curve obtained in Example 1 and the curve obtained by calculation;

[0051] Figures 5(a), (b) and (c) are multi-wavelength optical constant diagrams obtained in Example 1;

[0052] Figure 6 A comparison chart of the wavelength-reflectivity curve obtained in Example 2 and the curve obtained by calculation;

[0053] Figure 7 A comparison diagram of the wavelength-transmission Goos-Hanchen shift curve obtained in Example 2 and the curve obtained by calculation;

[0054] 8(a) and (b) are multi-wavelength optical constant diagrams obtained in Example 2. DETAILED DESCRIPTION

[0055] The present invention will be further described in detail below with reference to the accompanying drawings and specific examples. The following examples or drawings are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0056] Example 1:

[0057] like Figure 1 A method for detecting optical properties of multilayer thin films based on the combination of transmission Goos-Hanchen shift and spectroscopy is shown, comprising the following steps:

[0058] Step S1: measuring the position information of the light spot of the TM polarized wave transmitted through the multilayer film: using a transmission Goos-Hanchen shift measuring device to measure the position information of the light spot of the TM polarized wave transmitted through the multilayer film;

[0059] Step S2: Data processing to obtain an incident wavelength-transmission Gous-Hanchen shift relationship curve: Based on the light spot position information, the incident wavelength-transmission Gous-Hanchen shift relationship curve of the multilayer film is obtained, and then the transmission Gous-Hanchen shift under TM polarization is obtained;

[0060] Step S3: measuring spectral information of the multilayer film: using a spectral measurement device to measure the reflection spectrum data and transmission spectrum data of the TM polarized wave and the TE polarized wave of the multilayer film at a continuous wavelength λ, while keeping the incident angle and the incident point unchanged during the measurement process;

[0061] Step S4: Determine the type of the multilayer film: determine the film type of the multilayer film according to the measured reflection spectrum data and transmission spectrum data;

[0062] When the average reflectivity within the incident wavelength is greater than or equal to 0.95, the film type of the multilayer film is an anti-reflection film, and the process proceeds to step S5;

[0063] When the average transmittance within the incident wavelength is greater than or equal to 0.95, the film type of the multilayer film is an antireflection film, and the process proceeds to step S6;

[0064] When the average transmittance and the average reflectance within the incident wavelength are both 0.5±0.05, the film type of the multilayer film is a beam splitter film, and the process proceeds to step S7;

[0065] Step S5: When the multilayer film is determined to be an anti-reflection film, the transmitted Goos-Hanchen shift and the TM polarized wave reflection spectrum data are normalized to obtain reflectivity values ​​and transmitted Goos-Hanchen shift data sets of the same magnitude, and an anti-reflection film target function is established to calculate the optical constants of the anti-reflection film across the entire wavelength range.

[0066] Initialize the search range of the solution space {n, k, d}, use fitting calculation, judge the accuracy of the solution according to the size of the anti-reflection film target function, and obtain the anti-reflection film parameter vector a1 of the multilayer thin film when the anti-reflection film target function is minimized;

[0067] Step S6: When the multilayer film is determined to be an antireflection film, the transmission Gous-Hanchen shift and the transmission spectrum data of the TM polarized wave are normalized to obtain a data set of transmittance values ​​and transmission Gous-Hanchen shift values ​​of the same magnitude, and an antireflection film target function is established to calculate the optical constants of the antireflection film across the entire wavelength range.

[0068] Initializing the search range of the solution space {n, k, d}, using fitting calculation, judging the accuracy of the solution according to the magnitude of the antireflection film objective function, and obtaining the antireflection film parameter vector a2 of the multilayer thin film when the antireflection film objective function is minimized;

[0069] Step S7: When the multilayer film is determined to be a beamsplitter film, the transmitted Goos-Hanchen shift and the reflectance spectrum data of the TM polarized wave and the TE polarized wave are normalized to obtain reflectivity values ​​and transmitted Goos-Hanchen shift data sets of the same magnitude, establish a beamsplitter film target function, and calculate the optical constants of the beamsplitter film over the entire wavelength range;

[0070] Initialize the search range of the solution space {n, k, d}, use fitting calculation, judge the accuracy of the solution according to the size of the beam splitter objective function, and obtain the beam splitter parameter vector a3 of the multilayer film when the beam splitter objective function is minimized.

[0071] In step S1, when measuring using a transmission Goos-Hanchen shift measuring device, a three-phase thin film structure of substrate-multi-thin film layer-dielectric layer is used for detection; the multi-layer thin film is a multi-thin film layer plated on a substrate.

[0072] In step S2, the transmission Goos-Hanchen shift under the TM polarization wave Based on the transfer matrix method, the calculation expression is obtained by multiplying multiple matrices as follows:

[0073]

[0074] Where S represents the characteristic matrix of the multilayer thin film structure, λ represents the wavelength of the incident light, β represents the phase factor of the thin film layer; x represents the xth layer of the thin film, x∈[1,m]; q represents the optical transfer coefficient; ε represents the dielectric constant, and the real part of the dielectric constant ε real =n 2 -k 2 , the imaginary part of the dielectric constant ε imag =2nk, n represents the refractive index, k represents the extinction coefficient; i is the imaginary part, θ represents the incident angle;

[0075] For TM polarization waves, the optical transmission coefficient q of each layer in the multilayer film structure is f , transmission coefficient t TM , transmission phase Φ TM , reflection coefficient r TM and the transmitted Goos-Hanchen shift The calculation expressions are:

[0076]

[0077] Among them, S 11 、S 12 、S 21 、S 22 Represents a vector in a 2*2 matrix, p represents the basis, k x represents the incident light wave vector of the xth film layer, φ t represents the transmission phase, d represents the film thickness, k0 represents the incident light wave vector of the 0th layer of film, t represents the transmission coefficient, q0 represents the admittance of the incident interface, q N represents the admittance of the exit interface.

[0078] In step S5, the expression of the objective function of the anti-reflection film is as follows:

[0079]

[0080] Among them, F1 represents the target function of the anti-reflection film, N exp Indicates the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift under TM polarization wave obtained by inversion calculation; represents the transmitted Gous-Hanchen shift value of the i-th reference point under TM polarization wave extracted from the experimentally measured transmitted Gous-Hanchen shift curve; represents the reflectivity of the anti-reflection coating under TM polarization wave obtained by inversion calculation; represents the reflectivity of the anti-reflection film at the i-th reference point under the TM polarization wave extracted from the experimentally measured reflectivity curve; a1 represents the anti-reflection film parameter vector, a=(n1,k1,…nm,km), where m is the number of layers of the multilayer film, m≥2; n represents the refractive index, k represents the extinction coefficient, and d represents the film thickness; the subscript cal represents that obtained by inversion calculation, the subscript exp represents that obtained from experimental measurement, and the superscript TM represents the transverse magnetic wave.

[0081] In step S6, the expression of the antireflection film objective function is as follows:

[0082]

[0083] Among them, F2 represents the target function of the antireflection film, N exp Indicates the total number of incident wavelengths;

[0084] represents the transmitted Goos-Hanchen shift under TM polarization wave obtained by inversion calculation; represents the transmitted Gous-Hanchen shift value of the i-th reference point under TM polarization wave extracted from the experimentally measured transmitted Gous-Hanchen shift curve; represents the transmittance of the AR coating under TM polarization wave obtained by inversion calculation; represents the transmittance of the AR coating at the i-th reference point under TM polarization wave extracted from the experimentally measured transmittance curve, and a2 represents the AR coating parameter vector.

[0085] In formula (2), the calculation expression of the transmittance of the antireflection film is as follows:

[0086]

[0087] In step S7, the beam splitter objective function is expressed as follows:

[0088]

[0089] Among them, F3 represents the beam splitter objective function, N exp Indicates the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift under TM polarization wave obtained by inversion calculation; represents the transmitted Gous-Hanchen shift value of the ith reference point under TM polarization extracted from the experimentally measured transmitted Gous-Hanchen shift curve; R 3_cal (i,a3) represents the reflectivity of the beam splitter film obtained by inversion calculation; R 3_exp (i) represents the reflectivity of the beamsplitter film at the i-th reference point extracted from the experimentally measured reflectivity curve, and a3 represents the beamsplitter film parameter vector.

[0090] In formula (3), the calculation expression of the beam splitter film reflectivity R3 is as follows:

[0091]

[0092] in, represents the beam splitter reflection coefficient under TM polarization, represents the reflection coefficient of the beamsplitter film under TE polarization.

[0093] This embodiment adopts Figure 2 The four-phase structure of the multilayer film shown is a structure of substrate-multi-film layer-dielectric layer. The substrate is made of BK7 glass with a refractive index n p =1.5151; the medium is air, and its refractive index n a = 1. When the dielectric layer is made of other materials, the corresponding refractive index value of the dielectric can be used.

[0094] In Example 1, the incident light is selected as [400,800]. Initialize the solution space {n1, k1, d1, n2, k2, d2, n3, k3, d3}, the solution domain of n1 is [0,3], the solution domain of k1 is [0,2], the solution domain of d1 is [0,200], the solution domain of n2 is [0,3], the solution domain of k2 is [0,2], the solution domain of d2 is [0,100], the solution domain of n3 is [0,3], the solution domain of k3 is [0,2], the solution domain of d3 is [0,100]. Through step S4, it is determined that the film is an anti-reflection film, so the transmission Goos-Hanchen shift and reflection spectrum data are substituted into step S6, and the characteristic parameters of the film are obtained according to the minimum value of the objective function. From Figure 3 and Figure 4 The fitted transmission Goos-Hanchen shift and transmittance curves closely match the experimentally obtained curves, demonstrating that the film characteristic parameters obtained by this method are reliable and effective. Figure 5 shows the optical constants of the film calculated using this method. d1 = 124.90 nm, d2 = 82.10 nm, and d3 = 53.37 nm.

[0095] Example 2:

[0096] Example 2 is based on Example 1, and the difference is that in Example 2, the incident light is selected as [400, 1000]. Initialize the solution space {n1, k1, d1, n2, k2, d2}, the solution domain of n1 is [0, 3], the solution domain of k1 is [0, 2], the solution domain of d1 is [0, 300], the solution domain of n2 is [0, 3], the solution domain of k2 is [0, 2], and the solution domain of d2 is [0, 200]. Through step S4, it is determined that the film is an anti-reflection film, so the transmission Goos-Hanchen shift and reflection spectrum data are substituted into step S6, and the characteristic parameters of the film are obtained according to the minimum value of the objective function. From Figure 6 and Figure 7 The fitted transmission Goos-Hanchen shift and transmittance curves closely match the experimentally obtained curves, demonstrating that the film characteristic parameters obtained by this method are reliable and effective. Figure 8 shows the optical constants of the film calculated using this method. d1 = 235.70 nm, d2 = 157.64 nm.

[0097] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for detecting the optical properties of multilayer thin films based on the combination of transmission Goos-Hanchen shift and spectroscopy, characterized by: The following steps are involved: Step S1: measuring the position information of the light spot of the TM polarized wave transmitted through the multilayer film: using a transmission Goos-Hanchen shift measuring device to measure the position information of the light spot of the TM polarized wave transmitted through the multilayer film; Step S2: Data processing to obtain an incident wavelength-transmission Gous-Hanchen shift relationship curve: Based on the light spot position information, the incident wavelength-transmission Gous-Hanchen shift relationship curve of the multilayer film is obtained, and then the transmission Gous-Hanchen shift under TM polarization is obtained; Step S3: measuring spectral information of the multilayer film: using a spectral measurement device to measure the reflection spectrum data and transmission spectrum data of the TM polarized wave and the TE polarized wave of the multilayer film at a continuous wavelength λ, while keeping the incident angle and the incident point unchanged during the measurement process; Step S4: Determine the type of the multilayer film: determine the film type of the multilayer film according to the measured reflection spectrum data and transmission spectrum data; When the average reflectivity within the incident wavelength is greater than or equal to 0.95, the film type of the multilayer film is an anti-reflection film, and the process proceeds to step S5; When the average transmittance within the incident wavelength is greater than or equal to 0.95, the film type of the multilayer film is an antireflection film, and the process proceeds to step S6; When the average transmittance and the average reflectance within the incident wavelength are both 0.5±0.05, the film type of the multilayer film is a beam splitter film, and the process proceeds to step S7; Step S5: When the multilayer film is determined to be an anti-reflection film, the transmitted Goos-Hanchen shift and the TM polarized wave reflection spectrum data are normalized to obtain reflectivity values ​​and transmitted Goos-Hanchen shift data sets of the same magnitude, and an anti-reflection film target function is established to calculate the optical constants of the anti-reflection film across the entire wavelength range. Initialize the search range of the solution space {n, k, d}, use fitting calculation, judge the accuracy of the solution according to the size of the anti-reflection film target function, and obtain the anti-reflection film parameter vector a1 of the multilayer thin film when the anti-reflection film target function is minimized; The expression of the objective function of the anti-reflection film is as follows: Among them, F1 represents the target function of the anti-reflection film, N exp Indicates the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift under TM polarization wave obtained by inversion calculation; represents the transmitted Gous-Hanchen shift value of the i-th reference point under TM polarization wave extracted from the experimentally measured transmitted Gous-Hanchen shift curve; represents the reflectivity of the anti-reflection coating under TM polarization wave obtained by inversion calculation; represents the reflectivity of the anti-reflection film at the i-th reference point under the TM polarization wave extracted from the experimentally measured reflectivity curve; a1 represents the anti-reflection film parameter vector, a=(n1, k1, …nm, km), where m is the number of layers of the multilayer film, m≥2; n represents the refractive index, k represents the extinction coefficient, and d represents the film thickness; the subscript cal represents that obtained by inversion calculation, the subscript exp represents that obtained by experimental measurement, and the superscript TM represents the transverse magnetic wave; Step S6: When the multilayer film is determined to be an antireflection film, the transmission Gous-Hanchen shift and the transmission spectrum data of the TM polarized wave are normalized to obtain a data set of transmittance values ​​and transmission Gous-Hanchen shift values ​​of the same magnitude, and an antireflection film target function is established to calculate the optical constants of the antireflection film across the entire wavelength range. Initializing the search range of the solution space {n, k, d}, using fitting calculation, judging the accuracy of the solution according to the magnitude of the antireflection film objective function, and obtaining the antireflection film parameter vector a2 of the multilayer thin film when the antireflection film objective function is minimized; Step S7: When the multilayer film is determined to be a beamsplitter film, the transmitted Goos-Hanchen shift and the reflectance spectrum data of the TM polarized wave and the TE polarized wave are normalized to obtain reflectivity values ​​and transmitted Goos-Hanchen shift data sets of the same magnitude, establish a beamsplitter film target function, and calculate the optical constants of the beamsplitter film over the entire wavelength range; Initialize the search range of the solution space {n, k, d}, use fitting calculation, judge the accuracy of the solution according to the size of the beam splitter objective function, and obtain the beam splitter parameter vector a3 of the multilayer film when the beam splitter objective function is minimized.

2. The method for detecting optical properties of multilayer thin films based on transmission Goos-Hanchen shift and spectroscopy according to claim 1, characterized in that: In step S1, when measuring using a transmission Goos-Hanchen shift measuring device, a three-phase thin film structure of substrate-multi-thin film layer-dielectric layer is used for detection; the multi-layer thin film is a multi-thin film layer plated on a substrate.

3. The method for detecting optical properties of multilayer thin films based on transmission Goos-Hanchen shift and spectroscopy according to claim 2, characterized in that: In step S2, the transmission Goos-Hanchen shift under the TM polarization wave Based on the transfer matrix method, the calculation expression is obtained by multiplying multiple matrices as follows: Where S represents the characteristic matrix of the multilayer thin film structure, λ represents the wavelength of the incident light, β represents the phase factor of the thin film layer; x represents the xth layer of the thin film, x∈[1,m]; q represents the optical transfer coefficient; ε represents the dielectric constant, and the real part of the dielectric constant ε real =n 2 -k 2 , the imaginary part of the dielectric constant ε imag =2nk, n represents the refractive index, k represents the extinction coefficient; i is the imaginary part, θ represents the incident angle; For TM polarization waves, the optical transmission coefficient q of each layer in the multilayer film structure is f , transmission coefficient t TM , transmission phase Φ TM , reflection coefficient r TM and the transmission Goos-Hanchen shift The calculation expressions are: Among them, S 11 、S 12 、S 21 、S 22 Represents a vector in a 2*2 matrix, p represents the basis, k x represents the incident light wave vector of the xth film layer, φ t represents the transmission phase, d represents the film thickness, k0 represents the incident light wave vector of the 0th layer of film, t represents the transmission coefficient, q0 represents the admittance of the incident interface, q N represents the admittance of the exit interface.

4. The method for detecting optical properties of multilayer thin films based on transmission Goos-Hanchen shift and spectroscopy according to claim 1, characterized in that: In step S6, the expression of the antireflection film objective function is as follows: Among them, F2 represents the target function of the antireflection film, N exp Indicates the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift under TM polarization wave obtained by inversion calculation; represents the transmitted Gous-Hanchen shift value of the i-th reference point under TM polarization wave extracted from the experimentally measured transmitted Gous-Hanchen shift curve; represents the transmittance of the AR coating under TM polarization wave obtained by inversion calculation; represents the transmittance of the AR coating at the i-th reference point under TM polarization wave extracted from the experimentally measured transmittance curve, and a2 represents the AR coating parameter vector.

5. The method for detecting optical properties of multilayer thin films based on transmission Goos-Hanchen shift and spectroscopy according to claim 4, characterized in that: In formula (2), the calculation expression of the transmittance of the antireflection film is as follows:

6. The method for detecting optical properties of multilayer thin films based on transmission Goos-Hanchen shift and spectroscopy according to claim 1, characterized in that: In step S7, the beam splitter objective function is expressed as follows: Among them, F3 represents the beam splitter objective function, N exp Indicates the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift under TM polarization wave obtained by inversion calculation; represents the transmitted Gous-Hanchen shift value of the ith reference point under TM polarization extracted from the experimentally measured transmitted Gous-Hanchen shift curve; R 3_cal (i,a3) represents the reflectivity of the beam splitter film obtained by inversion calculation; R 3_exp (i) represents the reflectivity of the beamsplitter film at the i-th reference point extracted from the experimentally measured reflectivity curve, and a3 represents the beamsplitter film parameter vector.

7. The method for detecting optical properties of multilayer thin films based on transmission Goos-Hanchen shift and spectroscopy according to claim 6, characterized in that: In formula (3), the calculation expression of the beam splitter film reflectivity R3 is as follows: in, represents the beam splitter reflection coefficient under TM polarization, represents the reflection coefficient of the beamsplitter film under TE polarization.

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