Multilayer medium measurement method and system

Abstract

The invention provides a multilayer medium measurement method and system. According to the invention, the multi-layer medium transparent sample is formed by fitting a plurality of two medium layers, and a spectral signal cannot be returned at the fitting position. The method comprises the following steps: obtaining a multilayer medium transparent sample and at least two spectrograms corresponding to any horizontal position of each medium layer; respectively calculating the thickness of the multilayer dielectric transparent sample and the refractive index of each dielectric layer; and calculating the thickness of each dielectric layer at the position based on one spectrogram at any position of the multilayer dielectric transparent sample, the thickness of the multilayer dielectric transparent sample and the refractive index of each dielectric layer. According to the invention, an effective solution is provided for thickness measurement of the transparent material under the multi-medium condition and for the situation that effective information of the intermediate medium cannot be returned.

Description

Technical Field

[0001] The present invention relates to the technical field of optical detection, and particularly relates to a method and system for measuring multi-layer media. Background Art

[0002] Spectral confocal technology is a non-contact measurement method with ultra-high precision and stability, and is widely used in the field of precision detection. The spectral confocal measurement method utilizes the axial dispersion of the continuous broadband spectrum of a polychromatic light source under a dispersive lens, and can measure parameters such as micro displacement, distance, and thickness by analyzing the echo spectrum of the object to be measured.

[0003] In view of the measurement principle of spectral confocal, this method has little relation with the surface of the material to be measured and is less affected. Compared with the measurement of the triangular reflection method, there is almost no requirement for the reflection angle, and it has strong environmental adaptability and is insensitive to external factors such as temperature. Therefore, spectral confocal systems are widely used in the measurement of various flat plate thicknesses and micro displacements.

[0004] For example, Chinese Patent CN 117704977 B discloses a transparent flat plate two-dimensional thickness measurement system and method based on line spectral confocal technology. This patent decodes the spectral-distance mapping relationship through a microprocessor to obtain the thickness measurement result on the confocal line, and cooperates with a two-dimensional precision translation stage to realize the two-dimensional surface thickness measurement of a large-area transparent flat plate, improving the measurement efficiency. The technical problem solved by this patent is different from that of the present application.

[0005] Compared with the technical solution of improving the measurement efficiency proposed in the above patent, for the common technical problem of reducing measurement errors in spectral confocal technology, the master's thesis of Zhejiang University, Research on Thickness Detection System Based on Spectral Confocal (DOI: 10.27461 / d.cnki.gzjdx.2020.003471) details how to establish a bidirectional opposed system based on the principle of spectral confocal technology, and the process of measuring the thickness of different transparent flat plates and transparent flat plates. In addition, during the measurement process, the mathematical model of thickness measurement is analyzed in detail, and corresponding compensation methods and formulas are proposed to reduce the thickness measurement error.

[0006] In addition to the relevant compensation content recorded in the thesis, for the compensation calculation of the refractive index, Chinese Patent CN 113514425B discloses a calibration device and calibration method for the refractive index of a plane isopachous medium. This patent improves the accuracy of the predicted refractive index curve by correcting the wavelength term coefficient in the apochromatic characteristic formula, and then obtains the accurate refractive index formula of the sample to be measured, and at the same time obtains the accurate refractive index curve of the sample. The technical problem solved by this patent is different from that of the present application.

[0007] In addition to the compensation calculation for measuring thickness in the above-mentioned conventional cases, for the compensation calculation of refractive index under multi-media conditions, Chinese Patent CN 118168464 B discloses a method and device for measuring the thickness and thinning thickness of flat parts in a liquid environment. This patent reconstructs a model of the corresponding parameters - displacement of the spectral peak center adapted to the sensor after the structural change. After calculating the surface position based on this model, it also corrects the measurement result based on the measurement environment to achieve accurate on-line measurement of the thickness and thinning thickness of flat parts. In the multi-media conditions proposed in this patent, when the spectral confocal displacement sensor measures it, there are two focal positions, namely the focal position at point A on the wafer and the focal position at point C on the lower surface of the wafer; according to the corresponding parameters of the spectral peak center, the distance between the spectral confocal displacement sensor and the upper surface of the wafer and the distance between the spectral confocal displacement sensor and the lower surface of the wafer can be calculated.

[0008] Chinese Patent CN 102052904 B discloses a method for measuring the physical thickness of each layer of a multi-layer film based on the optical thickness of each layer of the multi-layer film. The method includes: (a) setting the refractive index of the layer; (b) using the refractive index to calculate the coefficient matrix; (c) providing light to the multi-layer film to measure the optical thickness according to the light reflected by the multi-layer film; and (d) calculating the physical thickness according to the optical thickness and the coefficient matrix. According to the description of this patent, visible light, X-rays, infrared rays or radioactive rays can be used, and a sensor can be used to detect the amount of attenuation of light by the multi-layer film to be measured, and the film thickness can be measured. In this way, the physical thickness of all layers of the multi-layer film that cannot be detected by the method of measuring reflected light can be accurately measured. The technical means and technical problems of this patent are different from those of the present application.

[0009] In addition, the thickness measurement of transparent materials under multi-media conditions and the inability to obtain detection information for each medium layer are different technical problems, and no effective solution has been retrieved for this. Summary of the Invention

[0010] The present invention proposes a multi-layer medium measurement method and system, which solves at least one of the above technical problems.

[0011] To achieve the above object, the present invention proposes the following technical solutions: A multi-layer medium measurement method, wherein the multi-layer medium transparent sample is formed by laminating a certain number of two medium layers, and no spectral signal can be returned at the lamination, and the method includes: Using a line spectral confocal sensor to scan the multi-layer medium transparent sample and any two opposite surfaces of each medium layer respectively, and obtaining at least two spectral images corresponding to any horizontal position of the multi-layer medium transparent sample and each medium layer respectively; Calculate the thickness of a multi-layered transparent sample based on multiple spectral maps at any horizontal position of the multi-layered transparent sample and the installation position relationship; calculate the refractive index of each medium layer based on multiple spectral maps at any horizontal position of each medium layer and the installation position relationship. Calculate the thickness of each medium layer at this position based on a single spectral map at any position of the multi-layered transparent sample, the thickness of the multi-layered transparent sample, and the refractive index of each medium layer.

[0012] Further, the two medium layers have the same color, or any one of the medium layers is colorless.

[0013] Further, the installation position relationship includes: at the same horizontal position, at least one line spectral confocal sensor is respectively arranged at corresponding positions on two opposite surfaces, and multiple line spectral confocal sensors at the two corresponding positions are aligned so that the measurement ranges of the multiple line spectral confocal sensors at the two corresponding positions overlap in the vertical direction, and the overlapping height is not less than the thickness of the object to be measured; the vertical distance between the light exit ports of two line spectral confocal sensors at different corresponding positions is used as the installation position relationship; the object to be measured includes a multi-layered transparent sample and each medium layer.

[0014] Further, the installation position relationship includes: setting a line spectral confocal sensor, realizing the relative flipping of the object to be measured and the line spectral confocal sensor, and obtaining the spectral maps corresponding to two corresponding positions on the opposite surfaces of the object to be measured; the object to be measured includes a multi-layered transparent sample and each medium layer; based on the measurement range of the line spectral confocal sensor, calculate the installation position relationship.

[0015] Further, it also includes: calibrating the position of the line spectral confocal sensor and calibrating the parameters of the line spectral confocal sensor to obtain the measurement height corresponding to each wavelength in any spectral map, the angle between the incident light and the optical axis corresponding to each wavelength, and the installation position relationship, so as to realize the calculation of the thickness and / or refractive index.

[0016] Based on the same inventive concept, the present application also proposes a multi-layered medium measurement system, including: A line spectral confocal sensor for scanning any two opposite surfaces of the object to be measured; The object to be measured includes a multi-layered transparent sample and each medium layer of the multi-layered transparent sample; the multi-layered transparent sample is formed by laminating a certain number of two medium layers, and no spectral signal can be returned at the lamination position of the multi-layered transparent sample; A spectrometer opposite to the reflection surface of the line spectral confocal sensor, for obtaining and analyzing the wavelength distribution of the reflected light of the object to be measured, and generating two spectral maps corresponding to any horizontal position of the multi-layered transparent sample and each medium layer; A calculation module calculates the thickness of a multi-layer dielectric transparent sample based on multiple spectral images at any horizontal position of the multi-layer dielectric transparent sample and the installation position relationship; calculates the refractive index of each dielectric layer based on multiple spectral images at any horizontal position of each dielectric layer and the installation position relationship; and calculates the thickness of each dielectric layer at this position based on one spectral image at any position of the multi-layer dielectric transparent sample, the thickness of the multi-layer dielectric transparent sample, and the refractive index of each dielectric layer.

[0017] Further, it further includes: a calibration module for calibrating the parameters of the line spectral confocal sensor to obtain the measurement height corresponding to each wavelength in any spectral image and the angle between the incident light and the optical axis corresponding to each wavelength, so as to realize the calculation of the thickness and / or refractive index; and it is also used to calibrate the position of the line spectral confocal sensor to obtain the installation position relationship, so as to realize the calculation of the thickness and / or refractive index.

[0018] Further, it further includes: a support mechanism for fixing the installation position of the line spectral confocal sensor and the installation position of the object to be measured.

[0019] Further, it further includes: a rotation mechanism connected to the support mechanism for realizing the relative flipping of the object to be measured and the line spectral confocal sensor, so that the line spectral confocal sensor scans any two opposite surfaces of the object to be measured.

[0020] On the other hand, the present invention also proposes a computer-readable storage medium storing a computer program, which when executed by a processor causes the processor to execute the method described above.

[0021] The beneficial effects of the embodiments of the present invention are as follows: The embodiment of the present application proposes a multi-layer dielectric measurement system, which uses a line spectral confocal sensor and related installation structures to obtain at least two spectral images at the same horizontal position of the opposite surfaces of the object to be measured; wherein, the object to be measured includes a multi-layer dielectric transparent sample and each dielectric layer. Based on the spectral images, the thickness of each dielectric layer in the multi-layer dielectric transparent sample is calculated to solve the technical problem that the thickness of a single dielectric layer cannot be obtained for a multi-layer dielectric transparent sample.

[0022] The embodiment of the present application proposes a multi-layer dielectric measurement method. According to the imaging principle of the line spectral confocal sensor, by analyzing the multiple refraction phenomena of the incident light entering the interior of the object to be measured from the propagation medium where the dispersion lens group of the line spectral confocal sensor is located, combined with Fresnel's law and geometric relationships, the refractive index formula of a single dielectric layer and the thickness calculation formula of a single dielectric layer are deduced from the data information corresponding to the spectral image of the object to be measured, so as to improve the accuracy of the detection result.

[0023] In addition, the measurement systems in the embodiments of the present application all use line spectral confocal sensors to obtain the spectral images of the object to be measured. Each scan can obtain the spectral information at each position on a scan line, and the calculation efficiency is higher. When using a line spectral confocal sensor to scan and measure the object to be measured, there is no need to contact the object to be measured, and there is no damage to the object to be measured.

[0024] Meanwhile, the measurement method proposed in the embodiments of the present application takes any coordinate position as the calculation object, and uses the spectral information obtained by the line spectral confocal sensor, with higher accuracy and improved accuracy of the calculation results.

[0025] The measurement method proposed in the embodiments of the present application provides an effective solution for the thickness measurement of transparent materials under multi-medium conditions and for the case where the effective information of the intermediate medium cannot be returned, and realizes the thickness measurement of a single medium layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a schematic diagram of the measurement system proposed by the present invention; Figure 2 is a schematic structural diagram of the measurement system in Embodiment 1 of the present invention; Figure 3 is a schematic structural diagram of the measurement system in Embodiment 2 of the present invention; Figure 4 is a schematic flow diagram of the measurement method of the present invention; Figure 5 is a schematic diagram of position calibration in Embodiment 3 of the present invention; Figure 6 is a schematic diagram of refractive index calculation in Embodiment 3 of the present invention; Figure 7 is a schematic diagram of refractive index calculation in Embodiment 4 of the present invention; Figure 8 is a schematic diagram of position calibration in Embodiment 6 of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention.

[0028] As Figure 1 shown, the present application proposes a multi-layer medium measurement system, including: A line spectral confocal sensor for scanning any two opposite surfaces of the object to be measured.

[0029] The object to be measured includes a multi-layer dielectric transparent sample and each dielectric layer of the multi-layer dielectric transparent sample; the multi-layer dielectric transparent sample is formed by laminating a certain number of two dielectric layers, and no spectral signal can be returned at the lamination position of the multi-layer dielectric transparent sample. Among them, any two opposite surfaces of the object to be measured are the upper surface and the lower surface of the object to be measured, or the left surface and the right surface of the object to be measured, or the front surface and the back surface of the object to be measured.

[0030] A spectrometer, opposite to the reflecting surface of the line spectral confocal sensor, is used to acquire and analyze the wavelength distribution of the reflected light of the object to be measured, and generate two spectral maps corresponding to any horizontal position of the multi-layer dielectric transparent sample and each dielectric layer.

[0031] A calculation module calculates the thickness of the multi-layer dielectric transparent sample based on multiple spectral maps at any horizontal position of the multi-layer dielectric transparent sample and the installation position relationship; calculates the refractive index of each dielectric layer based on multiple spectral maps at any horizontal position of each dielectric layer and the installation position relationship; calculates the thickness of each dielectric layer at this position based on one spectral map at any position of the multi-layer dielectric transparent sample, the thickness of the multi-layer dielectric transparent sample, and the refractive index of each dielectric layer.

[0032] Preferably, it further includes: a calibration module, which is used to calibrate the parameters of the line spectral confocal sensor to obtain the measurement height corresponding to each wavelength in any spectral map and the angle between the incident light corresponding to each wavelength and the optical axis, so as to realize the calculation of the thickness and / or refractive index; it is also used to calibrate the position of the line spectral confocal sensor to obtain the installation position relationship and realize the calculation of the thickness and / or refractive index.

[0033] Preferably, it further includes: a support mechanism, which is used to fix the installation position of the line spectral confocal sensor and the installation position of the object to be measured.

[0034] Preferably, it further includes: a rotation mechanism, connected to the support mechanism, which is used to realize the relative flipping of the object to be measured and the line spectral confocal sensor, so that the line spectral confocal sensor scans any two opposite surfaces of the object to be measured. Embodiment 1

[0035] As Figure 2 shown, in the measurement system proposed in this application, a line spectral confocal sensor can be set, combined with a rotation mechanism, to realize the scanning of any two opposite surfaces of the object to be measured by the line spectral confocal sensor, and obtain the spectral maps corresponding to two corresponding positions on the opposite surfaces of the object to be measured. Calculate the installation position relationship based on the measurement range of the line spectral confocal sensor.

[0036] To ensure the accuracy of the detection results, the surface of the object to be measured needs to be relatively flat to ensure that the heights of the horizontal plane positions corresponding to the scanning of any two opposite surfaces of the object to be measured by the line spectral confocal sensor are the same, so as to reduce the detection error.

[0037] In addition, when the rotation mechanism realizes the relative flipping of the object to be measured and the line spectral confocal sensor, the scanning lines of the line spectral confocal sensor on any two opposite surfaces of the object to be measured coincide in the projection in the vertical direction of the object to be measured, so as to obtain two spectral maps corresponding to the same horizontal position of the object to be measured.

[0038] Furthermore, the support mechanism and the rotation mechanism can be an integral structure or a split structure. Embodiment 2

[0039] In the measurement system proposed in this application, at least one line spectral confocal sensor can also be respectively arranged at two corresponding positions on the opposite surfaces. By aligning the multiple line spectral confocal sensors at the two corresponding positions, the measurement ranges of the multiple line spectral confocal sensors at the two corresponding positions overlap in the vertical direction, and the overlapping height is not less than the thickness of the object to be measured, so as to obtain multiple spectral maps at the same horizontal position. In addition, taking the vertical distance between the light outlet ports of the two line spectral confocal sensors at different corresponding positions as the installation position relationship, the calculation of the thickness and / or refractive index is realized.

[0040] As Figure 3 shown, a line spectral confocal sensor is respectively arranged at the corresponding positions on the opposite surfaces, and the two line spectral confocal sensors are aligned so that the measurement ranges of the two line spectral confocal sensors overlap in the vertical direction, and the overlapping height is not less than the thickness of the object to be measured.

[0041] Preferably, a line spectral confocal sensor can also be arranged on one side of the object to be measured, and two or more line spectral confocal sensors are arranged on the other side opposite thereto. Embodiment 3

[0042] Based on any of the above measurement systems, this application proposes its usage method, that is, a multi-layer medium measurement method, as Figure 4 shown, specifically as follows: Use the line spectral confocal sensor to scan the multi-layer medium transparent sample and any two opposite surfaces of each medium layer respectively, and obtain at least two spectral maps corresponding to any horizontal position of the multi-layer medium transparent sample and each medium layer respectively.

[0043] Based on the multiple spectral maps at any horizontal position of the multi-layer medium transparent sample and the installation position relationship, calculate the thickness of the multi-layer medium transparent sample.

[0044] Based on the multiple spectral maps at any horizontal position of each medium layer and the installation position relationship, calculate the refractive index of each medium layer.

[0045] Based on one spectral map at any position of the multi-layer medium transparent sample, the thickness of the multi-layer medium transparent sample, and the refractive index of each medium layer, calculate the thickness of each medium layer at this position.

[0046] Before implementing the above measurement method, it further includes calibrating the line spectral confocal sensor, including: calibrating the position of the line spectral confocal sensor and the parameters of the line spectral confocal sensor, so as to obtain the measurement height corresponding to each wavelength in any spectral diagram, the angle between the incident light corresponding to each wavelength and the optical axis, and the installation position relationship, and realize the calculation of thickness and / or refractive index.

[0047] In this embodiment, the relevant content of the line spectral confocal sensor is only used as an example for illustration, and other calibration methods are also applicable. This application does not limit the sequence of parameter calibration and position calibration.

[0048] Among them, calibrating the parameters of the line spectral confocal sensor to obtain the measurement height corresponding to each wavelength in any spectral diagram and the angle between the incident light corresponding to each wavelength and the optical axis, and realize the calculation of thickness and / or refractive index. Regarding the parameter calibration process of the line spectral confocal sensor, the normalization fitting method or other methods can be used to implement it, and this application does not limit the specific implementation method.

[0049] Calibrating the position of the line spectral confocal sensor, obtaining the installation position relationship, and realizing the calculation of thickness and / or refractive index.

[0050] The installation position relationship includes: at least one line spectral confocal sensor is respectively arranged at the corresponding positions on two opposite surfaces at the same horizontal position, and the multiple line spectral confocal sensors at the two corresponding positions are aligned, so that the measurement ranges of the multiple line spectral confocal sensors at the two corresponding positions have a coincidence height in the vertical direction, and the coincidence height is not less than the thickness of the object to be measured; taking the vertical distance between the light outlet ports of the two line spectral confocal sensors at different corresponding positions as the installation position relationship; the object to be measured includes a multi-layer dielectric transparent sample and each dielectric layer.

[0051] In this embodiment, taking the installation method of respectively arranging at least one line spectral confocal sensor at two corresponding positions on the opposite surfaces as an example, that is, the content recorded in Embodiment 2, the process of obtaining the installation position relationship is described.

[0052] For the convenience of calculation and explanation, this embodiment takes the example of respectively arranging one line spectral confocal sensor on the upper surface and the lower surface of the object to be measured to illustrate the position calibration process.

[0053] By aligning the two line spectral confocal sensors at the two corresponding positions, the measurement ranges of the two line spectral confocal sensors at the two corresponding positions have a coincidence height in the vertical direction, and the coincidence height is not less than the thickness of the object to be measured. The object to be measured includes a multi-layer dielectric transparent sample and each dielectric layer.

[0054] The specific calibration process is as follows: As Figure 5As shown, a sensor coordinate system is established, which includes a first sensor coordinate system and a second sensor coordinate system.

[0055] For the line spectral confocal sensor above the object to be measured, taking the length direction of the light exit as the X1 axis, the optical axis direction of the upper line spectral confocal sensor as the Z1 axis, the direction perpendicular to the X1O1Z1 plane as the Y1 axis, and the center along the length direction of the light exit as the origin O1, a first sensor coordinate system is constructed.

[0056] For the line spectral confocal sensor below the object to be measured, taking the length direction of the light exit as the X2 axis, the optical axis direction of the lower line spectral confocal sensor as the Z2 axis, the direction perpendicular to the X2O2Z2 plane as the Y2 axis, and the center along the length direction of the light exit as the origin O2, a second sensor coordinate system is constructed.

[0057] A calibration coordinate system is established, with the intersection point of the upper surface, left surface and rear surface of the object to be measured as the origin, the two mutually perpendicular edges on the upper surface as the X axis and Y axis respectively, and the Z axis perpendicular to the upper surface.

[0058] In this embodiment, the positive direction of the X axis is the direction from the rear surface to the front surface, the positive direction of the Y axis is the direction from the left surface to the right surface, and the positive direction of the Z axis is the direction from the lower surface to the upper surface.

[0059] In this application, the X direction, Y direction, and Z direction all represent the axis directions corresponding to the calibration coordinate system.

[0060] Calculate the coordinates ('x s ,y s ,z s ) after translation at any position (x s ,'y s ,'z s ) of the object to be measured in the sensor coordinate system, as follows:

[0061] Among them, G s represents the vertical distance between the origin of the sensor coordinate system of the line spectral confocal sensor s and the origin of the calibration coordinate system. If the line spectral confocal sensor is set in the positive direction of the Z axis of the calibration coordinate system, then γ = 1; if the line spectral confocal sensor is set in the negative direction of the Z axis of the calibration coordinate system, then γ = -1.

[0062] Among them, △x s , △y s respectively represent the offsets of any sensor coordinate system relative to the calibration coordinate system in the x direction and y direction.

[0063] The offset can be calculated by using the coordinate data of any position of the object to be measured in three coordinate systems, or the relative position between the line spectral confocal sensor and the object to be measured can be adjusted in advance to determine the offset, or other methods can be used to obtain the offset.

[0064] In this embodiment, the vertical distance between the origin O1 of the first coordinate system of the line spectral confocal sensor 1 on the upper surface of the object to be measured and the origin O of the calibration coordinate system is G1, and the vertical distance between the origin O2 of the second coordinate system of the line spectral confocal sensor 2 on the lower surface of the object to be measured and the origin O of the calibration coordinate system is G2.

[0065] Since the object to be measured is arranged between two line spectral confocal sensors, then G1 + G2 = G; where G is the vertical distance between the two line spectral confocal sensors, that is, the vertical distance between the origin O1 of the first coordinate system and the origin O2 of the second coordinate system, to represent the installation position relationship between the two line spectral confocal sensors.

[0066] Furthermore, it can also be set as the relative movement in other two mutually perpendicular directions.

[0067] Calculate the rotation angles of the sensor coordinate system relative to the calibration coordinate system around each axis in sequence and perform transformations respectively. The specific transformation steps are as follows: Taking the line spectral confocal sensor 1 on the upper surface of the object to be measured as an example, the first sensor coordinate system is transformed based on the calibration coordinate system.

[0068] Based on the X-direction offset Δx1 and Y-direction offset Δy1 of the first sensor coordinate system relative to the calibration coordinate system; then the coordinates ('x1, 'y1, 'z1) after translation of any position (x1, y1, z1) of the object to be measured in the first sensor coordinate system are as follows:

[0069] When rotating around the X axis of the calibration coordinate system, it is known that the projection length of the line connecting the coordinate of a certain position of the object to be measured and the origin of the calibration coordinate system on the X axis of the calibration coordinate system is L1, and the projection length of the line connecting the coordinate of this position of the object to be measured and the origin of the calibration coordinate system on the X axis of the first sensor coordinate system scanned by the line spectral confocal sensor 1 is L2.

[0070] The rotation angle θx1 of the first sensor coordinate system relative to the calibration coordinate system around the X axis is θx1 = arccos(L1 / L2).

[0071] The transformed coordinates are:

[0072] In the formula, when the rotation direction around the X axis is counterclockwise, σ = -1; when the rotation direction around the X axis is clockwise, σ = 1.

[0073] When rotating around the Y-axis of the calibration coordinate system, the projection length of the line connecting a certain position coordinate of the object to be measured and the origin of the calibration coordinate system on the Z-axis of the calibration coordinate system is d1, while the projection length of the line connecting the same position coordinate of the object to be measured and the origin of the calibration coordinate system on the Z-axis of the first sensor coordinate system during the line spectral confocal sensor scanning is d2.

[0074] After the first sensor coordinate system is rotated around the X-axis, the rotation angle θy1 of the first sensor coordinate system relative to the calibration coordinate system around the Y-axis is θy1 = arccos(d1 / d2).

[0075] The transformed coordinates are:

[0076] In the formula, when the rotation direction around the Y-axis is counterclockwise, σ = -1; when the rotation direction around the Y-axis is clockwise, σ = 1.

[0077] When rotating around the Z-axis of the calibration coordinate system, the projection length of the line connecting a certain position coordinate of the object to be measured and the origin of the calibration coordinate system on the Y-axis of the calibration coordinate system is L3, while the projection length of the line connecting the same position coordinate of the object to be measured and the origin of the calibration coordinate system on the Y-axis of the first sensor coordinate system during the line spectral confocal sensor scanning is L4.

[0078] After the first sensor coordinate system is rotated around the Y-axis, the rotation angle θz1 of the first sensor coordinate system relative to the calibration coordinate system around the Z-axis is θz1 = arccos(L3 / L4).

[0079] The transformed coordinates are:

[0080] In the formula, when the rotation direction around the Z-axis is counterclockwise, σ = -1; when the rotation direction around the Z-axis is clockwise, σ = 1.

[0081] Through the above transformation process, the first sensor coordinate system is converted into the calibration coordinate system.

[0082] Similarly, based on the X-direction offset Δx2 and Y-direction offset Δy2 of the second sensor coordinate system relative to the calibration coordinate system; after translating and rotating any position (x2, y2, z2) of the object to be measured in the second sensor coordinate system, the transformed coordinates ('''x2, '''y2, '''z2) can be obtained, that is, the second sensor coordinate system is transformed into the calibration coordinate system.

[0083] The position calibration of the line spectral confocal sensors on the upper and lower surfaces of the object to be measured is completed.

[0084] Furthermore, any sensor coordinate can be used as a reference, and by translating and rotating other sensor coordinate systems and the calibration coordinate system, position calibration can be achieved.

[0085] After completing the position calibration, determine the installation position relationship G, and then do not change the position of the line spectral confocal sensor.

[0086] After completing the above calibration process, use the line spectral confocal sensor to scan the multi-layer dielectric transparent sample and any two opposite surfaces of each dielectric layer respectively, and obtain at least two spectral images corresponding to any horizontal position of the multi-layer dielectric transparent sample and each dielectric layer.

[0087] In this embodiment, since a line spectral confocal sensor is respectively arranged on the upper surface and the lower surface of the object to be measured, the line spectral confocal sensor is used to scan the upper surface and the lower surface of the object to be measured in sequence, and two spectral images at the same horizontal position of the object to be measured are obtained.

[0088] In this embodiment, the spectral image is a two-dimensional image, the column direction is the wavelength distribution direction, and the row direction is the spatial distribution direction.

[0089] For any horizontal position (x, y) of the object to be measured, the spectral images obtained by scanning with the upper surface spectral confocal sensor and the lower surface spectral confocal sensor. In any spectral image, sort the light intensities corresponding to each peak wavelength from large to small, and select the wavelength corresponding to the highest light intensity as the first peak wavelength λ1(x, y) s , and the wavelength corresponding to the second highest light intensity is the second peak wavelength λ2(x, y) s .

[0090] Based on the parameter calibration of the line spectral confocal sensor, obtain the first peak wavelength and the second peak wavelength in each spectral image, and the corresponding first measurement height d λ1 (x, y) s and the second measurement height d λ2 (x, y) s , and the angle θ between the incident light ray corresponding to the second peak wavelength in the propagation medium where the dispersion lens group is located and the optical axis s .

[0091] Among them, the measurement height corresponding to each peak wavelength is the measurement height in the propagation medium where the dispersion lens group of the line spectral confocal sensor is located at this peak wavelength. The propagation medium where the dispersion lens group is located can be air, a single gas, a liquid or other media. Determine the specific composition of the propagation medium according to the actual application scenario, and obtain the refractive index n1 of the propagation medium where the dispersion lens group is located.

[0092] Among them, the subscript s represents the serial number of the line spectral confocal sensor, indicating the corresponding relationship between the line spectral confocal sensor and the spectral image.

[0093] Taking the upper and lower surfaces of the object to be measured as examples, two spectral maps obtained for any object to be measured at the same horizontal position (x, y), namely the spectral map of the upper surface and the spectral map of the lower surface. Let s = 1 represent the spectral map corresponding to the upper surface, and s = 2 represent the spectral map corresponding to the upper surface.

[0094] In the spectral map of the upper surface, the wavelength corresponding to the highest light intensity is the first peak wavelength λ1(x, y)1, and the wavelength corresponding to the second highest light intensity is the second peak wavelength λ2(x, y)1, with the corresponding first measurement height d λ1 (x, y)1 and the second measurement height d λ2 (x, y)1, and the angle θ1 between the incident light ray corresponding to the second peak wavelength in the propagation medium where the dispersive lens group is located and the optical axis.

[0095] In the spectral map of the lower surface, the wavelength corresponding to the highest light intensity is the first peak wavelength λ1(x, y)2, and the wavelength corresponding to the second highest light intensity is the second peak wavelength λ2(x, y)2, with the corresponding first measurement height d λ1 (x, y)2 and the second measurement height d λ2 (x, y)2, and the angle θ2 between the incident light ray corresponding to the second peak wavelength in the propagation medium where the dispersive lens group is located and the optical axis.

[0096] Due to factors such as the line spectral sensor, the object to be measured, and the application environment, the specific values of the two first peak wavelengths and the two second peak wavelengths of the two spectral maps corresponding to the same horizontal position may be the same or different; then the specific values of the corresponding measurement heights and angles may be the same or different.

[0097] For the spectral map obtained by scanning with a line spectral confocal sensor on the upper surface of a multi-layer dielectric transparent sample, obtain the corresponding first measurement height d λ1 (x, y)1; for the spectral map obtained by scanning with a line spectral confocal sensor on the lower surface of a multi-layer dielectric transparent sample, obtain the corresponding first measurement height d λ1 (x, y)2.

[0098] Using the two first measurement heights d λ1 (x, y)1, d λ1 (x, y)2 and the installation position relationship G, calculate the thickness H(x, y) = G - d λ1 (x, y)1 - d λ1 (x, y)2.

[0099] In this application, the multi-layer dielectric transparent sample is formed by laminating a certain number of two dielectric layers, that is, by laminating a certain number of first dielectric layers and a certain number of second dielectric layers.

[0100] The present application does not limit the lamination sequence, that is, it can be the cross-lamination sequence of the first dielectric layer and the second dielectric layer, or the lamination sequence of several first dielectric layers after lamination and several second dielectric layers after lamination.

[0101] Taking the cross-lamination sequence as an example, as Figure 6 shown, the light rays emitted by the line spectral confocal sensor through the dispersion lens group enter the first dielectric layer (refractive index n2) from the propagation medium (refractive index n1) where the dispersion lens group is located at an incident angle a1 (i.e., θ s in the above text), and undergo the first refraction in the first dielectric layer, with the refraction angle being a2; the refracted light rays enter the second dielectric layer (refractive index n3) and undergo the second refraction in the second dielectric layer, with the refraction angle being a3, and finally converge to the lower surface of the second dielectric layer to return the spectral signal.

[0102] Based on the Fresnel's law, it can be known that in the above transformation process, there are: n1sin(a1) = n2sin(a2), n2sin(a2)= n3sin(a3).

[0103] Taking the spectral diagram obtained by the line spectral confocal sensor scanning the upper surface of the first dielectric layer, the first measurement height d λ1 (x,y) 1,M1 corresponding to the first peak wavelength λ1(x,y)1 is obtained; taking the spectral diagram obtained by the line spectral confocal sensor scanning the lower surface of the first dielectric layer, the first measurement height d λ1 (x,y) 2,M1 is obtained.

[0104] Similarly, for any spectral diagram obtained by scanning the upper surface or the lower surface of the first dielectric layer, the corresponding first measurement height d λ1 (x,y) s,M1 , the second measurement height d λ2 (x,y) s,M1 ; and the angle θ s,M1 between the incident light ray corresponding to the second peak wavelength in the propagation medium where the dispersion lens group is located and the optical axis are obtained.

[0105] Based on the geometric relationship, the calculation formula for the refractive index n2 of the first dielectric layer is as follows:

[0106] In the formula, n1 is the refractive index of the propagation medium where the dispersion lens group is located; G is the vertical distance between two line spectral confocal sensors, that is, the vertical distance between the origin O1 of the first coordinate system and the origin O2 of the second coordinate system, which is used to represent the installation position relationship between two line spectral confocal sensors.

[0107] Obtain the spectral diagram acquired by scanning the upper surface of the second dielectric layer with a line-spectrum confocal sensor, and obtain the corresponding first measured height d λ1 (x,y) 1,M2 ; Obtain the spectral diagram acquired by scanning the lower surface of the second dielectric layer with a line-spectrum confocal sensor, and obtain the corresponding first measured height d λ1 (x,y) 2,M2 .

[0108] For any spectral diagram obtained by scanning the upper surface or the lower surface of the second dielectric layer, obtain the corresponding first measured height d λ1 (x,y) s,M2 ; The second measured height d λ2 (x,y) s,M2 ; And the angle θ between the incident light ray corresponding to the second peak wavelength in the propagation medium where the dispersion lens group is located and the optical axis s,M2 .

[0109] Similarly, the calculation formula for the refractive index n3 of the second dielectric layer is as follows:

[0110] In the formula, n1 is the refractive index of the propagation medium where the dispersion lens group is located; G is the vertical distance between the two line-spectrum confocal sensors, that is, the vertical distance between the origin O1 of the first coordinate system and the origin O2 of the second coordinate system, to represent the installation position relationship between the two line-spectrum confocal sensors.

[0111] Through the above calculations, obtain the refractive index n2 of the first dielectric layer, the refractive index n3 of the second dielectric layer, and the thickness H of the multi-layer dielectric transparent sample.

[0112] The above calculation process of this application is only used as a calculation example for illustration, and the order of calculating the refractive index and the thickness of the dielectric layer can be adjusted arbitrarily according to actual needs. Further, the calculation of the refractive index of the dielectric layer and the calculation of the thickness of the multi-layer dielectric sample can also be calculated in parallel to improve the calculation efficiency.

[0113] In this embodiment, take a multi-layer dielectric transparent sample formed by laminating a first dielectric layer and a second dielectric layer as an example to calculate the thickness of each dielectric layer at any position.

[0114] As Figure 6 shown, for a spectral diagram corresponding to any horizontal position (x,y) of the multi-layer dielectric transparent sample, obtain the corresponding first measured height d λ1 (x,y) s and the second measured height d λ2 (x,y) s , and the angle θ between the incident light ray corresponding to the second peak wavelength in the propagation medium where the dispersion lens group is located and the optical axis s .

[0115] Based on the geometric relationship, the thickness H of the first dielectric layer M1 (x,y) The calculation formula is:

[0116] In the formula, H(x,y) is the thickness of the multi-layer dielectric transparent sample; n1 is the refractive index of the propagation medium where the dispersive lens group is located; n2 is the refractive index of the first dielectric layer; n3 is the refractive index of the second dielectric layer.

[0117] Based on the above calculation, it can be known that the thickness H of the second dielectric layer M2 (x,y)=H(x,y)-H M1 (x,y). Example 4

[0118] As Figure 7 shown, if the arrangement order of the combination method of the multi-layer dielectric transparent sample is the first dielectric layer, the second dielectric layer, and the first dielectric layer.

[0119] Then, during the process of scanning the multi-layer dielectric transparent sample with a line spectral confocal sensor, the light rays emitted by the line spectral confocal sensor through the dispersive lens group enter the upper first dielectric layer (refractive index n2) from the propagation medium (refractive index n1) where the dispersive lens group is located at an incident angle a1, and the first refraction occurs in the upper first dielectric layer, and the refraction angle is a2; the refracted light rays enter the second dielectric layer (refractive index n3), and the second refraction occurs in the second dielectric layer, and the refraction angle is a3; the refracted light rays enter the lower first dielectric layer (refractive index n2), and the third refraction occurs in the lower first dielectric layer, and the refraction angle is a4; finally, they converge to the lower surface of the lower first dielectric layer and return the spectral signal.

[0120] Based on the Fresnel's law, it can be known that in the above transformation process, there are: n1sin(a1) = n2sin(a2), n2sin(a2)= n3sin(a3), n3sin(a3)=n2sin(a4).

[0121] Since the refractive indices of the upper first dielectric layer and the lower first dielectric layer are the same, the refraction angles are also the same, that is, a2=a4.

[0122] For a spectral map corresponding to any horizontal position (x,y) of the multi-layer dielectric transparent sample, obtain the corresponding first measurement height d λ1 (x,y) s and the second measurement height d λ2 (x,y) s , and the angle θ between the incident light ray corresponding to the second peak wavelength in the propagation medium where the dispersive lens group is located and the optical axiss .

[0123] Based on the geometric relationship, the thickness H of the second dielectric layer M2 (x,y) The calculation formula is:[

[0124] In the formula, H(x,y) is the thickness of the multi-layer dielectric transparent sample; n1 is the refractive index of the propagation medium where the dispersion lens group is located; n2 is the refractive index of the first dielectric layer; n3 is the refractive index of the second dielectric layer.

[0125] Based on the above calculation, it can be known that the thickness H of the first dielectric layer M1 (x,y)=H(x,y)-H M2 (x,y). Example 5

[0126] If the arrangement order of the combination mode of the multi-layer dielectric transparent sample is several first dielectric layers and several second dielectric layers, then several first dielectric layers and several second dielectric layers are regarded as a whole respectively, and referring to the calculation formula of Example 3, calculate the thickness of the corresponding whole.

[0127] Calculate the thickness of a single dielectric layer by the ratio of the overall thickness to the number of dielectric layers. Example 6

[0128] If the measurement system described in Example 1 is adopted, only one line spectral confocal sensor is set, and by the relative flipping of the line spectral confocal sensor and the object to be measured, two spectral images corresponding to the same horizontal position of the relative surface of the object to be measured are obtained.

[0129] Before obtaining the spectral image of the object to be measured, the calibration process described in Example 3 can be adopted to determine the position of the line spectral confocal sensor and obtain the position relationship between the line spectral confocal sensor and the object to be measured.

[0130] The installation position relationship includes: setting one line spectral confocal sensor, realizing the relative flipping of the object to be measured and the line spectral confocal sensor, and obtaining the spectral images corresponding to two corresponding positions of the relative surface of the object to be measured; the object to be measured includes a multi-layer dielectric transparent sample and each kind of dielectric layer; based on the measurement range of the line spectral confocal sensor, calculate the installation position relationship.

[0131] Such as Figure 8 shown, during the calibration process, if the origin of the calibration coordinate system is set at any position on the lower surface of the object to be measured, then the vertical distance G' between the origin of the sensor coordinate system and the origin of the calibration coordinate system is used to represent the installation position relationship.

[0132] Alternatively, after determining the position of the line spectral confocal sensor, the vertical distance G' between the light outlet of the line spectral confocal sensor and the fixed position of the object to be measured can be obtained to represent the installation position relationship.

[0133] From the spectral diagram obtained by scanning the upper surface of the multi-layer dielectric transparent sample with the line spectral confocal sensor, the corresponding first measured height d λ1 (x,y)1; from the spectral diagram obtained by scanning the lower surface of the multi-layer dielectric transparent sample with the line spectral confocal sensor, the corresponding first measured height d λ1 (x,y)2.

[0134] With the two first measured heights d λ1 (x,y)1, d λ1 (x,y)2 and the installation position relationship G', calculate the thickness H(x,y) of the multi-layer dielectric transparent sample = (2G' - d λ1 (x,y)1 - d λ1 (x,y)2) / 2.

[0135] Meanwhile, in the refractive index calculation formula exemplified in Embodiment 3, G = G'. Embodiment 7

[0136] In this embodiment, considering the actual application, there may be a color requirement for the dielectric layer. For such a situation, the following preprocessing process is proposed: Before calibrating the line spectral confocal sensor, adjust the object to be measured within the corresponding dispersion measurement range of the line spectral confocal sensor, that is, the measurement range corresponding to the wavelength allowed to pass through by the current color of the object to be measured. To ensure the accuracy of the measurement results, the thickness of the multi-layer dielectric transparent sample is less than the measurement range corresponding to the wavelength allowed to pass through by the current color.

[0137] Meanwhile, the colors of the two dielectric layers are the same, or any one of the dielectric layers is colorless.

[0138] After the above preprocessing process, the measurement system and measurement method described in the above embodiments can be used to calculate the thickness of each dielectric layer.

[0139] Based on the same inventive concept, the present application also proposes a computer-readable storage medium, including a computer program, and when the computer program is executed by a processor, it implements the measurement method as described above.

[0140] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not conflict, it should be considered as the scope recorded in this specification.

[0141] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A multi-layer dielectric measurement method, characterized in that, The multi-layer dielectric transparent sample is formed by laminating a certain number of two dielectric layers, and no spectral signal can be returned at the lamination position. The method includes: Using a line spectral confocal sensor to scan any two opposite surfaces of the multi-layer dielectric transparent sample and each dielectric layer respectively, and obtaining at least two spectral maps corresponding to any horizontal position of the multi-layer dielectric transparent sample and each dielectric layer respectively; Calculating the thickness of the multi-layer dielectric transparent sample based on multiple spectral maps at any horizontal position of the multi-layer dielectric transparent sample and the installation position relationship; calculating the refractive index of each dielectric layer based on multiple spectral maps at any horizontal position of each dielectric layer and the installation position relationship; Calculating the thickness of each dielectric layer at this position based on one spectral map at any position of the multi-layer dielectric transparent sample, the thickness of the multi-layer dielectric transparent sample, and the refractive index of each dielectric layer.

2. The multi-layer dielectric measurement method according to claim 1, characterized in that, The two dielectric layers have the same color, or any one of the dielectric layers is colorless.

3. The multi-layer dielectric measurement method according to claim 1, characterized in that, The installation position relationship includes: at least one line spectral confocal sensor is respectively set at the corresponding positions of two opposite surfaces at the same horizontal position, and multiple line spectral confocal sensors at the two corresponding positions are aligned so that the measurement ranges of the multiple line spectral confocal sensors at the two corresponding positions overlap in the vertical direction, and the overlapping height is not less than the thickness of the object to be measured; the vertical distance between the light exit ports of two line spectral confocal sensors at different corresponding positions is used as the installation position relationship; the object to be measured includes the multi-layer dielectric transparent sample and each dielectric layer.

4. The multi-layer dielectric measurement method according to claim 1, characterized in that, The installation position relationship includes: setting a line spectral confocal sensor, realizing the relative flipping of the object to be measured and the line spectral confocal sensor, and obtaining the spectral maps corresponding to two corresponding positions on the opposite surfaces of the object to be measured; the object to be measured includes the multi-layer dielectric transparent sample and each dielectric layer; calculating the installation position relationship based on the measurement range of the line spectral confocal sensor.

5. The multi-layer dielectric measurement method according to claim 1, characterized in that, It also includes: Calibrating the position of the line spectral confocal sensor and calibrating the parameters of the line spectral confocal sensor to obtain the measurement height corresponding to each wavelength in any spectral map, the angle between the incident light and the optical axis corresponding to each wavelength, and the installation position relationship, so as to realize the calculation of the thickness and / or refractive index.

6. A multi-layer dielectric measurement system, characterized in that, It includes: A line spectral confocal sensor for scanning any two opposite surfaces of the object to be measured; The object to be measured includes a multi-layer dielectric transparent sample and each dielectric layer of the multi-layer dielectric transparent sample; the multi-layer dielectric transparent sample is formed by laminating a certain number of two dielectric layers, and no spectral signal can be returned at the lamination position of the multi-layer dielectric transparent sample; A spectrometer, opposite to the reflection surface of the line spectral confocal sensor, for obtaining and analyzing the wavelength distribution of the reflected light of the object to be measured, and generating two spectral maps corresponding to any horizontal position of the multi-layer dielectric transparent sample and each dielectric layer; A calculation module for calculating the thickness of the multi-layer dielectric transparent sample based on multiple spectral maps at any horizontal position of the multi-layer dielectric transparent sample and the installation position relationship; 7. The multi-layer dielectric measurement system according to claim 6, wherein Calculating the refractive index of each dielectric layer based on multiple spectral maps at any horizontal position of each dielectric layer and the installation position relationship; calculating the thickness of each dielectric layer at this position based on one spectral map at any position of the multi-layer dielectric transparent sample, the thickness of the multi-layer dielectric transparent sample, and the refractive index of each dielectric layer. It also includes: The calibration module is used to calibrate the parameters of the line spectral confocal sensor to obtain the measurement height corresponding to each wavelength in any spectral diagram, the angle between the incident light ray and the optical axis corresponding to each wavelength, and realize the calculation of thickness and / or refractive index; it is also used to calibrate the position of the line spectral confocal sensor, obtain the installation position relationship, and realize the calculation of thickness and / or refractive index.

8. The multi-layer dielectric measurement system according to claim 6, characterized in that, It further includes: The support mechanism is used to fix the installation position of the line spectral confocal sensor and the installation position of the object to be measured.

9. The multi-layer dielectric measurement system according to claim 6 or 8, characterized in that It further includes: The rotation mechanism is connected to the support mechanism and is used to realize the relative flipping of the object to be measured and the line spectral confocal sensor, so that the line spectral confocal sensor scans any two opposite surfaces of the object to be measured.

10. A computer-readable storage medium, characterized in that, A computer program is stored, and when the computer program is executed by a processor, the processor executes the method according to any one of claims 1 to 5.

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