Multilayer film optical property detection method based on combination of transmission Goos-Hanchen shift and spectrum

Abstract

The invention discloses a multi-layer film optical property detection method based on combination of transmission Goos-Hanchen shift and spectrum. The method is characterized by comprising the following steps: S1, measuring light spot position information of transmission TM polarized waves of a multi-layer film; s2, carrying out data processing to obtain an incident wavelength-transmission Goos-Hanchen shift relation curve; s3, measuring spectral information of the multi-layer thin film; s4, judging the type of the multi-layer thin film: entering S5 when the multi-layer thin film is a reflection increasing film, entering S6 when the multi-layer thin film is an antireflection film, and entering S7 when the multi-layer thin film is a beam splitting film; s5, establishing an objective function of the reflection increasing film, and calculating to obtain a parameter vector of the reflection increasing film when the objective function of the reflection increasing film is minimum; s6, establishing an anti-reflection film objective function, and calculating to obtain an anti-reflection film parameter vector when the anti-reflection film objective function is minimum; and S7, establishing a beam splitting film objective function, and calculating to obtain a beam splitting film parameter vector when the beam splitting film objective function is minimum. The method has the effect of improving the measurement efficiency and accuracy of the optical characteristics of the multi-layer film.

Description

Technical Field

[0001] The 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 spectrum. Background Art

[0002] With the widespread application of nano-scale thin films in the fields of microelectronics, optoelectronics, aerospace, medical instruments and polymer materials, thin film technology has become a research hotspot in the current scientific and technological research and industrial production fields. The continuous improvement and rapid development of thin film technology have also put forward higher requirements on various parameters of thin films. For example, the optical constants and thickness of thin films will play a decisive role in their optical properties, mechanical properties and electromagnetic properties. Among them, optical thin films are divided into anti-reflection films, anti-reflection films and spectroscopic films. In practical applications, multi-layer thin film superposition is usually used to increase the corresponding reflection, transmission and spectroscopic properties of the film. Therefore, it has become a vital technology to accurately detect the optical constants of nano-scale multi-layer thin films at the same time.

[0003] Disadvantages of existing technologies: Currently, most existing technologies use ellipsometry or photometry to obtain the characteristic parameters of thin films. However, the ellipsometry method has the problem of film thickness period, which will cause multiple solutions for the thickness of the film, thereby affecting the calculation of the optical constants. The photometry method is easily affected by the environment, resulting in inaccurate calculation results. And for different functional films, both the photometry method and the ellipsometry method have certain disadvantages. Summary of the invention

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

[0005] To achieve the above 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: comprising the following steps:

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

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

[0008] Step S3: measuring the spectral information of the multilayer film: using a spectral measurement device to measure the reflection spectral data and transmission spectral data of the TM polarized wave and the TE polarized wave of the multilayer film at a continuous wavelength λ, and 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 transmission Goos-Hanchen shift and the reflection spectrum data of the TM polarized wave are normalized to obtain the reflectivity value and the transmission Goos-Hanchen shift data set of the same order of magnitude, and the anti-reflection film target function is established to calculate the optical constants of the anti-reflection film in the full band;

[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 minimum;

[0015] Step S6: when the multilayer film is determined to be an anti-reflection film, the transmission Goos-Hanchen shift and the transmission spectrum data of the TM polarized wave are normalized to obtain a transmittance value and a transmission Goos-Hanchen shift data set of the same order of magnitude, and an anti-reflection film target function is established to calculate the optical constants of the anti-reflection film in the full band;

[0016] 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 a2 of the multilayer thin film when the anti-reflection film target function is minimum;

[0017] Step S7: when the multilayer film is determined to be a beam splitter film, the transmission Goos-Hanchen shift and the reflection spectrum data of the TM polarized wave and the TE polarized wave are normalized to obtain reflectivity values ​​and transmission Goos-Hanchen shift data sets of the same order of magnitude, establish a beam splitter film target function, and calculate the optical constants of the beam splitter film in the full band;

[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 film objective function, and obtain the beam splitter film parameter vector a3 of the multilayer film when the beam splitter film objective function is minimum.

[0019] Through the above design, the type of film 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 solved, which effectively solves the problem of a quick solution of the multilayer film parameters.

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

[0021] Preferably, 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] Among them, S represents the characteristic matrix of the multilayer film structure, λ represents the wavelength of the incident light, β represents the phase factor of the film layer; x represents the xth film layer, x∈[1,m]; q represents the optical transfer coefficient; v 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 polarized waves, the optical transfer 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:

[0025]

[0026]

[0027] Φ TM =arg(t TM ) (10)

[0028]

[0029] 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 x-th film, φ t represents the transmission phase, d represents the film thickness, k0 represents the incident light wave vector of the 0th film, t represents the transmission coefficient, q0 represents the admittance of the incident interface, q N Represents the admittance of the exit interface.

[0030] Preferably, in step S5, the expression of the objective function of the anti-reflection film is as follows:

[0031]

[0032] Among them, F1 represents the target function of the anti-reflection film, N exp Represents the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift of 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 film under TM polarization wave obtained by inversion calculation; It 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 parameter vector of the anti-reflection film, a=(n1,k1,…nm,km), wherein 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.

[0033] Preferably, in step S6, the expression of the antireflection film objective function is as follows:

[0034]

[0035] Where F2 represents the antireflection film target function, N exp Represents the total number of incident wavelengths;

[0036] represents the transmitted Goos-Hanchen shift of 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 film under TM polarization wave obtained by inversion calculation; represents the transmittance of the AR coating at the i-th reference point under the TM polarization wave extracted from the experimentally measured transmittance curve, and a2 represents the AR coating parameter vector.

[0037] As a preferred embodiment: In formula (2), the transmittance of the antireflection film is The calculation expression is as follows:

[0038]

[0039] Preferably, in step S7, the beam splitter film objective function is expressed as follows:

[0040]

[0041] Among them, F3 represents the beam splitter objective function, N exp Represents the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift of TM polarization wave obtained by inversion calculation; represents the transmission Gous-Hanchen shift value of the ith reference point under TM polarization wave extracted from the experimentally measured transmission 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.

[0042] As a preferred embodiment, in formula (3), the calculation expression of the beam splitting film reflectivity R3 is as follows:

[0043]

[0044] in, represents the beam splitter film reflection coefficient under TM polarization, It represents the reflection coefficient of the beam splitter film under TE polarization wave.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] (1) Using incident light of continuous wavelength band for measurement, selecting the combined characterization mode of spectrum and transmission Goos-Hanchen shift, and simultaneously realizing the solution of thin film optical constants at multiple wavelengths, 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, and improving the solution accuracy;

[0047] (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;

[0048] (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

[0049] Figure 1 It is a flow chart of the present invention for measuring parameters of multilayer thin films based on transmission Goos-Hanchen shift and spectroscopy;

[0050] Figure 2 is a schematic diagram of the prismatic thin film multilayer structure used in Example 1;

[0051] Figure 3 is a comparison diagram of the wavelength-transmittance curve obtained in Example 1 and the curve obtained by calculation;

[0052] Figure 4 is a comparison diagram of the wavelength-transmission Goos-Hanchen shift curve obtained in Example 1 and the curve obtained by calculation;

[0053] 5(a), (b) and (c) are multi-wavelength optical constant diagrams obtained in Example 1;

[0054] Figure 6 A comparison diagram of the wavelength-reflectivity curve obtained in Example 2 and the curve obtained by calculation;

[0055] Figure 7 A comparison diagram of the wavelength-transmission Goos-Hanchen shift curve obtained in Example 2 and the curve obtained by calculation;

[0056] 8(a) and (b) are multi-wavelength optical constant diagrams obtained in Example 2. DETAILED DESCRIPTION

[0057] The present invention is further described in detail below in conjunction with the accompanying drawings and specific examples. The following examples or drawings are used to illustrate the present invention, but are not used to limit the scope of the present invention.

[0058] Embodiment 1:

[0059] like Figure 1 As shown: A method for detecting optical properties of multilayer thin films based on transmission Goos-Hanchen shift and spectroscopy, comprising the following steps:

[0060] Step S1: measuring the light spot position information of the TM polarized wave transmitted through the multilayer film: using a transmission Goos-Hanchen shift measuring device to measure the light spot position information of the TM polarized wave transmitted through the multilayer film;

[0061] Step S2: Data processing to obtain an incident wavelength-transmission Goos-Hanchen shift relationship curve: According to the light spot position information, the incident wavelength-transmission Goos-Hanchen shift relationship curve of the multilayer film is obtained, and then the transmission Goos-Hanchen shift under TM polarization wave is obtained;

[0062] Step S3: measuring the spectral information of the multilayer film: using a spectral measurement device to measure the reflection spectral data and transmission spectral data of the TM polarized wave and the TE polarized wave of the multilayer film at a continuous wavelength λ, and keeping the incident angle and the incident point unchanged during the measurement process;

[0063] 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;

[0064] 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;

[0065] 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;

[0066] 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;

[0067] Step S5: when the multilayer film is determined to be an anti-reflection film, the transmission Goos-Hanchen shift and the reflection spectrum data of the TM polarized wave are normalized to obtain the reflectivity value and the transmission Goos-Hanchen shift data set of the same order of magnitude, and the anti-reflection film target function is established to calculate the optical constants of the anti-reflection film in the full band;

[0068] 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 minimum;

[0069] Step S6: when the multilayer film is determined to be an anti-reflection film, the transmission Goos-Hanchen shift and the transmission spectrum data of the TM polarized wave are normalized to obtain a transmittance value and a transmission Goos-Hanchen shift data set of the same order of magnitude, and an anti-reflection film target function is established to calculate the optical constants of the anti-reflection film in the full band;

[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 anti-reflection film target function, and obtain the anti-reflection film parameter vector a2 of the multilayer thin film when the anti-reflection film target function is minimum;

[0071] Step S7: when the multilayer film is determined to be a beam splitter film, the transmission Goos-Hanchen shift and the reflection spectrum data of the TM polarized wave and the TE polarized wave are normalized to obtain reflectivity values ​​and transmission Goos-Hanchen shift data sets of the same order of magnitude, establish a beam splitter film target function, and calculate the optical constants of the beam splitter film in the full band;

[0072] 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 film objective function, and obtain the beam splitter film parameter vector a3 of the multilayer film when the beam splitter film objective function is minimum.

[0073] In the step S1, when the transmission Goos-Hanchen shift measuring device is used for measurement, the substrate-multi-thin film layer-dielectric layer is used as a three-phase thin film structure for detection; the multi-layer thin film is a multi-thin film layer plated on the substrate.

[0074] 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:

[0075]

[0076] Among them, S represents the characteristic matrix of the multilayer film structure, λ represents the wavelength of the incident light, β represents the phase factor of the film layer; x represents the xth film layer, 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;

[0077] For TM polarized waves, the optical transfer 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:

[0078]

[0079] Φ TM =arg(t TM ) (10)

[0080]

[0081] Among them, S 11 , S 12 , S21 , S 22 represents a vector in a 2*2 matrix, p represents the basis, k x represents the incident light wave vector of the x-th film, φ t represents the transmission phase, d represents the film thickness, k0 represents the incident light wave vector of the 0th film, t represents the transmission coefficient, q0 represents the admittance of the incident interface, q N Represents the admittance of the exit interface.

[0082] In step S5, the expression of the anti-reflection film objective function is as follows:

[0083]

[0084] Among them, F1 represents the target function of the anti-reflection film, N exp Represents the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift of 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 film under TM polarization wave obtained by inversion calculation; It 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 parameter vector of the anti-reflection film, a=(n1,k1,…nm,km), wherein 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.

[0085] In step S6, the expression of the anti-reflection film objective function is as follows:

[0086]

[0087] Where F2 represents the antireflection film target function, N exp Represents the total number of incident wavelengths;

[0088] represents the transmitted Goos-Hanchen shift of 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 film under TM polarization wave obtained by inversion calculation; represents the transmittance of the AR coating at the i-th reference point under the TM polarization wave extracted from the experimentally measured transmittance curve, and a2 represents the AR coating parameter vector.

[0089] In formula (2), the calculation expression of the transmittance of the antireflection film is as follows:

[0090]

[0091] In step S7, the beam splitter objective function is expressed as follows:

[0092]

[0093] Among them, F3 represents the beam splitter objective function, N exp Represents the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift of TM polarization wave obtained by inversion calculation; represents the transmission Gous-Hanchen shift value of the ith reference point under TM polarization wave extracted from the experimentally measured transmission 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.

[0094] In formula (3), the calculation expression of the beam splitting film reflectivity R3 is as follows:

[0095]

[0096] in, represents the beam splitter film reflection coefficient under TM polarization, It represents the reflection coefficient of the beam splitter film under TE polarization wave.

[0097] This embodiment adopts Figure 2 The four-phase structure of the multilayer film shown in the figure is a structure of substrate-multi-film layer-medium layer. The substrate is made of BK7 glass, whose refractive index n p =1.5151; the medium is air, and its refractive index n a = 1. When the medium layer is made of other materials, the corresponding medium refractive index value can be used.

[0098] 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 It can be seen that the transmission Goos-Hanchen shift and transmittance curves obtained by fitting are almost well matched with the experimental curves, indicating that the film characteristic parameters obtained by this method are reliable and effective. d1 = 124.90nm, d2 = 82.10nm, d3 = 53.37nm, Figure 5 shows the optical constants of the film calculated by the present invention.

[0099] Embodiment 2:

[0100] 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 It can be seen that the transmission Goos-Hanchen shift and transmittance curves obtained by fitting are almost well matched with the experimental curves, indicating that the film characteristic parameters obtained by this method are reliable and effective. d1 = 235.70nm, d2 = 157.64nm, Figure 8 shows the optical constants of the film calculated by the present invention.

[0101] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for detecting optical properties of multilayer thin films based on transmission Goos-Hanchen shift and spectroscopy, characterized in that: The following steps are involved: Step S1: measuring the light spot position information of the TM polarized wave transmitted through the multilayer film: using a transmission Goos-Hanchen shift measuring device to measure the light spot position information of the TM polarized wave transmitted through the multilayer film; Step S2: Data processing to obtain an incident wavelength-transmission Goos-Hanchen shift relationship curve: According to the light spot position information, the incident wavelength-transmission Goos-Hanchen shift relationship curve of the multilayer film is obtained, and then the transmission Goos-Hanchen shift under TM polarization wave is obtained; Step S3: measuring the spectral information of the multilayer film: using a spectral measurement device to measure the reflection spectral data and transmission spectral data of the TM polarized wave and the TE polarized wave of the multilayer film at a continuous wavelength λ, and 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 transmission Goos-Hanchen shift and the reflection spectrum data of the TM polarized wave are normalized to obtain the reflectivity value and the transmission Goos-Hanchen shift data set of the same order of magnitude, and the anti-reflection film target function is established to calculate the optical constants of the anti-reflection film in the full band; 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 minimum; Step S6: when the multilayer film is determined to be an anti-reflection film, the transmission Goos-Hanchen shift and the transmission spectrum data of the TM polarized wave are normalized to obtain a transmittance value and a transmission Goos-Hanchen shift data set of the same order of magnitude, and an anti-reflection film target function is established to calculate the optical constants of the anti-reflection film in the full band; 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 a2 of the multilayer thin film when the anti-reflection film target function is minimum; Step S7: when the multilayer film is determined to be a beam splitter film, the transmission Goos-Hanchen shift and the reflection spectrum data of the TM polarized wave and the TE polarized wave are normalized to obtain reflectivity values ​​and transmission Goos-Hanchen shift data sets of the same order of magnitude, establish a beam splitter film target function, and calculate the optical constants of the beam splitter film in the full band; 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 film objective function, and obtain the beam splitter film parameter vector a3 of the multilayer film when the beam splitter film objective function is minimum.

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 the step S1, when the transmission Goos-Hanchen shift measuring device is used for measurement, the substrate-multi-thin film layer-dielectric layer is used as a three-phase thin film structure for detection; the multi-layer thin film is a multi-thin film layer plated on the 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: Among them, S represents the characteristic matrix of the multilayer film structure, λ represents the wavelength of the incident light, β represents the phase factor of the film layer; x represents the xth film layer, 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 polarized waves, the optical transfer 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 x-th film, φ t represents the transmission phase, d represents the film thickness, k0 represents the incident light wave vector of the 0th 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 S5, the expression of the anti-reflection film objective function is as follows: Among them, F1 represents the target function of the anti-reflection film, N exp Represents the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift of TM polarization wave obtained by inversion calculation; represents the transmitted Gous-Hanchen shift value of the ith reference point under TM polarization wave extracted from the experimentally measured transmitted Gous-Hanchen shift curve; represents the reflectivity of the anti-reflection film under TM polarization wave obtained by inversion calculation; It 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 parameter vector of the anti-reflection film, a=(n1,k1,…nm,km), wherein 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.

5. 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 anti-reflection film objective function is as follows: Where F2 represents the antireflection film target function, N exp Represents the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift of 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 film under TM polarization wave obtained by inversion calculation; represents the transmittance of the AR coating at the i-th reference point under the TM polarization wave extracted from the experimentally measured transmittance curve, and a2 represents the AR coating parameter vector.

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

7. 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 Represents the total number of incident wavelengths; represents the transmitted Goos-Hanchen shift of TM polarization wave obtained by inversion calculation; represents the transmission Gous-Hanchen shift value of the ith reference point under TM polarization wave extracted from the experimentally measured transmission 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.

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

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