Spectral confocal interference measurement system, method and device based on double-channel single spectrometer

Abstract

The invention provides a spectrum confocal interference measurement system, method and device based on a double-channel single spectrometer. The spectrum confocal interference measurement method comprises the steps that an optical fiber coupling unit equally divides a broadband light source into a first input light source and a second input light source; the measuring assembly is used for simultaneously measuring a to-be-measured sample through the first input light source and the second input light source to respectively obtain a confocal signal and an interference signal, and transmitting the confocal signal and the interference signal to the optical fiber coupling unit to obtain an addition signal of the confocal signal and the interference signal; the first processing unit is used for collecting addition signals; the second processing unit obtains the confocal thickness and the optical thickness of the to-be-measured sample according to the addition signal; and the physical thickness and the refractive index of the to-be-measured sample are obtained according to the confocal thickness and the optical thickness. According to the invention, on the basis of not increasing the hardware cost and not reducing the system efficiency, the problem that the chromatography resolution is limited is solved.

Description

Technical Field

[0001] The present disclosure relates to the field of thin film thickness and refractive index measurement, and particularly to a spectral confocal interference measurement system, method, and device based on a dual-channel single spectrometer. Background Art

[0002] The measurement of thin film thickness and refractive index is of great significance in fields such as material fabrication, material property optimization, optical element design, quality control, and material uniformity. The thickness of a thin film is closely related to its physical, chemical, and mechanical properties. For example, only when the packaging thin film has good thickness uniformity can the properties such as tensile strength and barrier property be consistent everywhere to effectively protect the contents. For the insulating thin film in electronic components, only when the thickness is precise can stable insulating performance be provided to prevent leakage and short circuit and ensure the normal operation of electronic devices. In mass production, accurately measuring the thin film thickness can ensure that the thickness of each roll and each batch of thin films meets the standard and remains consistent. For applications with high requirements for thickness accuracy, such as optical thin films used in the manufacture of precision optical instruments, consistent thickness can ensure the consistency of optical performance and improve the imaging quality. By accurately measuring the thin film thickness, waste of raw materials caused by excessive thickness can be avoided, precise use of raw materials can be achieved, material costs can be reduced, and at the same time, the production of unqualified products caused by uneven thickness can be reduced, and the rework cost can be reduced. The thickness measurement data can provide a basis for adjusting production process parameters. For example, parameters such as temperature, pressure, and speed affect the thin film thickness. Timely adjustment according to the measurement results can keep the production process in the best state and improve production efficiency and product quality stability.

[0003] However, the main problem of the existing spectral confocal interference imaging technology is limited tomographic resolution. Although a single spectral acquisition ensures the measurement speed, the acquired signal is the product of the confocal signal and the interference signal, resulting in a very narrow bandwidth of the interference signal, so that the tomographic resolution is limited to the 0.1 mm level and cannot be improved.

[0004] Based on this, there is an urgent need to develop a spectral confocal interference measurement system that can simultaneously measure the thickness and refractive index of a thin film and solve the problem of limited tomographic resolution. Summary of the Invention

[0005] A spectral confocal interference measurement system, method, and device based on a dual-channel single spectrometer are proposed in the present disclosure to solve at least one technical problem in the prior art. The specific steps are as follows:

[0006] A spectral confocal interference measurement system based on a dual-channel single spectrometer includes:

[0007] An optical fiber coupling unit for receiving a broadband light source and generating a first input light source and a second input light source by equally dividing the broadband light source;

[0008] A measurement component, which is optically conductively connected to the optical fiber coupling unit, is used to simultaneously measure a sample to be measured through the first input light source and the second input light source, respectively obtain a confocal signal and an interference signal, and transmit the confocal signal and the interference signal to the optical fiber coupling unit to obtain an added signal of the confocal signal and the interference signal;

[0009] A first processing unit, which performs data interaction with the optical fiber coupling unit, is used to collect the added signal;

[0010] A second processing unit, which performs data interaction with the first processing unit, is used to obtain the confocal thickness and optical thickness of the sample to be measured according to the added signal; and then obtain the physical thickness and refractive index of the sample to be measured according to the confocal thickness and optical thickness.

[0011] The measurement component includes:

[0012] A first measurement unit, which is connected to the optical fiber coupling unit, is used to measure the sample to be measured by using the first input light source and obtain a confocal signal;

[0013] A second measurement mechanism, which is connected to the optical fiber coupling unit, is used to measure the sample to be measured by using the second input light source and obtain an interference signal;

[0014] The first measurement unit and the second measurement mechanism perform data interaction with the optical fiber coupling unit to transmit the confocal signal and the interference signal to the optical fiber coupling unit to obtain an added signal of the confocal signal and the interference signal.

[0015] The second measurement mechanism includes:

[0016] An interference optical unit, which is connected to the optical fiber coupling unit, is used to receive the second input light source;

[0017] A first beam splitter, which is arranged at the output end of the interference optical unit;

[0018] A second beam splitter, which is arranged in parallel with the first beam splitter and is located above the sample to be measured.

[0019] A measurement method based on the above measurement system includes:

[0020] Receiving a broadband light source and generating a first input light source and a second input light source by splitting the broadband light source equally;

[0021] Through the first input light source and the second input light source, the sample to be measured is measured simultaneously by the first measurement unit and the second measurement mechanism to obtain a confocal signal and an interference signal respectively, and the confocal signal and the interference signal are transmitted to the fiber optic coupling unit to obtain an added signal of the confocal signal and the interference signal;

[0022] Collect the added signal, and obtain the confocal thickness and optical thickness of the sample to be measured according to the added signal;

[0023] Obtain the physical thickness and refractive index of the sample to be measured according to the confocal thickness and optical thickness.

[0024] The simultaneous measurement of the sample to be measured to obtain the added signal of the confocal signal and the interference signal includes:

[0025] The added signal is formed by adding the collected confocal signal and the interference signal, expressed as:

[0026]

[0027] where λ is the wavelength of the broadband light source; M represents the number of surfaces of the sample to be measured; d conf0 , ɑ, and b are relevant parameters of the first measurement unit and the second measurement mechanism; I0 and I1 are the light intensities reflected from the front and back surfaces of the sample to be measured respectively; φ j0 represents the initial phase of the interference signal; d int represents the optical thickness of the sample to be measured;

[0028] And obtain the confocal thickness and optical thickness of the sample to be measured according to the formula of the added signal.

[0029] The obtaining of the confocal thickness and optical thickness of the sample to be measured according to the formula of the added signal includes:

[0030] Set the relationship between the confocal depth and the wavelength as: d conf (λ) = bλ + d conf0 ;

[0031] Determine the confocal depths d conf1 and d conf2 of the front and back surfaces of the sample to be measured by finding the peak wavelengths λ1 and λ2, and the obtained confocal thickness is: d conf = d conf1 - d conf2 ;

[0032] For each surface inside the sample to be measured, there will be a frequency in the interference signal, and the frequency f k = d int / π is proportional to the optical depth, and the optical thickness of the sample to be measured is obtained according to the frequency of the Fourier transform of the collected interference signal. k is the wave number.

[0033] Obtaining the physical thickness of the sample to be measured according to the confocal thickness and the optical thickness includes:

[0034] The physical thickness d of the sample to be measured is obtained by the following formula:

[0035]

[0036] where NA is the numerical aperture of the dispersion confocal probe CCP; d conf is the confocal thickness of the sample to be measured; d int is the optical thickness of the sample to be measured.

[0037] The method for obtaining the refractive index of the sample to be measured includes:

[0038] The refractive index n of the sample to be measured is: n = d int / d;

[0039] where d int is the optical thickness of the sample to be measured; d is the physical thickness of the sample to be measured.

[0040] An electronic device for thickness measurement includes:

[0041] A storage medium for storing a computer program;

[0042] A processing unit that exchanges data with the storage medium and is used to execute the computer program through the processing unit when measuring the thin film thickness, and perform the steps of the measurement method as described above.

[0043] A readable storage medium:

[0044] The readable storage medium stores a computer program;

[0045] When the computer program runs, it executes the steps of the measurement method as described above.

[0046] Beneficial effects:

[0047] The beneficial effects of the present disclosure at least include: The measurement system described in the present disclosure adopts dual-channel synchronous acquisition, replacing the original single-channel acquisition method. While ensuring the measurement efficiency, it avoids the superposition of confocal signals and interference signals in a multiplicative manner, increasing the tomographic resolution by one order of magnitude, reaching the order of 0.01 mm, and it can be further increased by increasing the light source bandwidth. Moreover, by adopting the method of increasing channels without increasing spectrometers, the increase in system hardware costs is avoided. And after adopting the system structure of dual-channel synchronous acquisition, interference can be formed on the front and back surfaces of the thin film, and the confocal and interference signals are superposed in an additive manner. Therefore, the part of the reference arm in the original system can be removed, which also avoids the increase in system hardware costs and complexity. On the basis of not increasing hardware costs and not reducing system efficiency, the present disclosure proposes a spectral confocal interference sensor with a dual-channel single spectrometer, solving the problem of limited tomographic resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 is a schematic diagram of the optical path structure of the measurement system described in the present disclosure;

[0049] Figure 2 is the signal obtained by the spectral confocal interference sensor and filtering method of a dual-channel single spectrometer;

[0050] Figure 2 (a) is the signal collected by the sensor;

[0051] Figure 2 (b) is the confocal signal separated by using low-pass filtering;

[0052] Figure 2 (c) is the interference signal separated by using high-pass filtering;

[0053] Figure 2 (d) is the result after Fourier transform of the interference signal;

[0054] Figure 3 (a) is the schematic diagram of the principle of the commercial OCT measurement method;

[0055] Figure 3 (b) is the imaging cross-sectional view of the commercial OCT measuring a 0.3 mm PET film. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] In the following, various embodiments of the present disclosure will be described more comprehensively. The present disclosure can have various embodiments, and adjustments and changes can be made therein. However, it should be understood that there is no intention to limit the various embodiments of the present disclosure to the specific embodiments disclosed herein, but the present disclosure should be understood to cover all adjustments, equivalents, and / or alternative solutions falling within the spirit and scope of the various embodiments of the present disclosure.

[0057] Hereinafter, the term "comprise" or "may comprise" used in various embodiments of the present disclosure indicates the presence of the disclosed functions, operations, or elements, and does not limit the addition of one or more functions, operations, or elements. Further, as used in various embodiments of the present disclosure, the terms "comprise", "have", and their cognates are only intended to indicate a specific feature, number, step, operation, element, component, or combination of the foregoing items, and should not be construed as precluding the existence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations of the foregoing items first.

[0058] In various embodiments of the present disclosure, the expression "or" or "at least one of A or / and B" includes any combination or all combinations of the listed words. For example, the expression "A or B" or "at least one of A or / and B" may include A, may include B, or may include both A and B.

[0059] Expressions (such as "first", "second", etc.) used in various embodiments of the present disclosure may modify various constituent elements in the various embodiments, but do not limit the corresponding constituent elements. For example, the above expressions do not limit the order and / or importance of the elements. The above expressions are only for the purpose of distinguishing one element from other elements. For example, the first user device and the second user device indicate different user devices, although both are user devices. For example, without departing from the scope of the various embodiments of the present disclosure, the first element may be referred to as the second element, and similarly, the second element may also be referred to as the first element.

[0060] It should be noted that: if it is described that one constituent element is "connected" to another constituent element, the first constituent element may be directly connected to the second constituent element, and a third constituent element may be "connected" between the first constituent element and the second constituent element. Conversely, when one constituent element is "directly connected" to another constituent element, it can be understood that there is no third constituent element between the first constituent element and the second constituent element.

[0061] The term "user" used in various embodiments of the present disclosure may indicate a person who uses an electronic device or a device that uses an electronic device (e.g., an artificial intelligence electronic device).

[0062] The terms used in various embodiments of the present disclosure are for the purpose of describing specific embodiments only and are not intended to limit the various embodiments of the present disclosure. As used herein, the singular forms are also intended to include the plural forms unless the context clearly indicates otherwise. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the various embodiments of the present disclosure pertain. The terms (such as those defined in a general use dictionary) will be interpreted to have the same meaning as the contextual meaning in the relevant technical field and will not be interpreted to have an idealized meaning or an overly formal meaning unless clearly defined in the various embodiments of the present disclosure.

[0063] The current methods for measuring film thickness and refractive index mainly include the following several:

[0064] 1) Ellipsometry: When a polarized light beam is incident on the film surface, reflection and refraction occur on the upper and lower surfaces of the film, and the polarization states of the reflected light and the refracted light change. Ellipsometry is to obtain the optical parameters of the film by precisely measuring this change in polarization state. Generally, the refractive index is used to describe the optical properties of the film, and there is a specific mathematical relationship between it and the change in the polarization states of the reflected light and the incident light. By measuring and analyzing these relationships, parameters such as the refractive index and thickness of the film can be calculated. However, its disadvantages are also very obvious. During the measurement, the process is very complex, and it is difficult to process and analyze the data.

[0065] 2) Prism coupling method: The film to be measured is placed very close to the prism surface. When the evanescent wave interacts with the film, if the optical properties of the film (such as refractive index n, thickness d, etc.) meet certain conditions, the energy of the evanescent wave will be coupled into the film, exciting the guided wave mode in the film. At this time, at a specific incident angle, effective coupling of light energy from the prism to the film occurs, causing the light intensity that was originally totally reflected in the prism to decrease significantly at certain angles. By measuring these angles and other parameters, the refractive index, thickness, etc. of the film can be calculated. Similarly, its disadvantage is also that the process is complex during the measurement, and it is necessary to precisely adjust the relative position and angle between the prism and the sample, and the operation difficulty is large.

[0066] 3) Spectrophotometry: When light irradiates the film surface, reflection and transmission occur on the upper and lower surfaces of the film respectively, and an optical path difference is generated between the two reflected light beams, thus forming an interference phenomenon. According to the theory of light interference, the position and intensity of the interference fringes are related to factors such as the thickness and refractive index of the film and the wavelength of the incident light. By measuring the intensity distribution of the reflected light or the transmitted light at different wavelengths, that is, obtaining the spectrophotometric data, and then using relevant physical models and algorithms to analyze these data, the thickness and refractive index of the film can be calculated. The disadvantage of this method is that it is greatly affected by the substrate and temperature.

[0067] 4) Spectral interferometry: Using a broadband light source, the emitted light passes through a beam splitter, with one beam striking the thin film sample and reflecting off the upper and lower surfaces. These two reflected beams interfere with a reference beam on the detector, forming interference fringes. Because light of different wavelengths travels along different optical paths in the film, the interference fringes vary with wavelength. Analysis of the interference spectrum reveals the optical path difference (OPD), and the film thickness and refractive index can be calculated based on their relationship. However, this method has the disadvantages of long measurement times, the need for multiple measurements, and complex data processing.

[0068] 5) Spectral confocal interferometry: The confocal measurement scheme underestimates the geometric thickness due to refraction. The confocal thickness is related to the geometric thickness, refractive index, and numerical aperture. The interferometry scheme measures the optical path length, which reflects the product of the geometric thickness and the refractive index. By analyzing the measured spectral signal, the confocal thickness and optical thickness are obtained. By combining the formulas for confocal and interferometry measurements, the geometric thickness and refractive index can be calculated. Its advantage is that a single spectral acquisition can simultaneously measure thickness and refractive index, with fast measurement speed and non-contact measurement. Subsequent development into fiber optic sensors will further enhance flexibility and practicality. However, the main problem with existing spectral confocal interferometry is the limited tomographic resolution. Although a single spectral acquisition guarantees measurement speed, the acquired signal is the product of the confocal signal and the interference signal, resulting in a very narrow interference signal bandwidth, which limits the tomographic resolution to the 0.1mm level and cannot be improved.

[0069] Based on this, the present disclosure provides the following embodiments to solve the above technical problems. Specific embodiment 1:

[0071] The present disclosure discloses an embodiment:

[0072] like Figure 1, A spectral confocal interference measurement system based on a dual-channel single spectrometer, comprising: an optical fiber coupling unit 1, a measurement component 2, a first processing unit 3, and a second processing unit 4; wherein, the optical fiber coupling unit 1 is used to receive a broadband light source and generate a first input light source and a second input light source by splitting the broadband light source equally; the measurement component 2 is optically connected to the optical fiber coupling unit 1 and is used to simultaneously measure a sample to be measured A through the first input light source and the second input light source, respectively obtain a confocal signal and an interference signal, and transmit the confocal signal and the interference signal to the optical fiber coupling unit 1 to obtain an added signal of the confocal signal and the interference signal; the first processing unit 3 exchanges data with the optical fiber coupling unit 1 and is used to collect the added signal; the second processing unit 4 exchanges data with the first processing unit 3 and is used to obtain the confocal thickness and optical thickness of the sample to be measured according to the added signal; and then obtain the physical thickness and refractive index of the sample to be measured according to the confocal thickness and optical thickness.

[0073] In this embodiment, the optical fiber coupling unit 1 is a 50:50 optical fiber coupler; the first processing unit 3 is a spectrometer; the second processing unit 4 is a computer or other processable intelligent unit.

[0074] Further, the measurement component 2 includes: a first measurement unit 201 and a second measurement mechanism 202; wherein, the first measurement unit 201 is connected to the optical fiber coupling unit 1 and is used to measure the sample to be measured A by using the first input light source to obtain a confocal signal; the second measurement mechanism 202 is connected to the optical fiber coupling unit 1 and is used to measure the sample to be measured A by using the second input light source to obtain an interference signal; the first measurement unit 201 and the second measurement mechanism 202 exchange data with the optical fiber coupling unit 1 and are used to transmit the confocal signal and the interference signal to the optical fiber coupling unit 1 to obtain an added signal of the confocal signal and the interference signal.

[0075] Further, the second measurement mechanism 202 includes: an interference optical unit 2021, a first beam splitter 2022, and a second beam splitter 2023; wherein, the interference optical unit 2021 is connected to the optical fiber coupling unit 1 and is used to receive the second input light source; the first beam splitter 2022 is arranged at the output end of the interference optical unit 2021; the second beam splitter 2023 is arranged in parallel with the first beam splitter 2022 and is located above the sample to be measured A.

[0076] Preferably, the interference optical unit 2021 is an interference probe; the first beam splitter 2022 and the second beam splitter 2023 are both semi-transmissive and semi-reflective beam splitters; the first measurement unit 201 is a chromatic confocal probe.

[0077] During specific use, the light emitted by the broadband light source through the optical fiber passes through a 50:50 optical fiber coupler and is split into two. 50% of the light passes through the optical fiber into the dispersive confocal probe, illuminating the sample A to be tested to generate a confocal signal, while the other 50% of the light passes through the optical fiber into the interference probe, passes through two semi-transparent and semi-reflective beam splitters, and illuminates the front and back surfaces of the sample A to be tested to generate an interference signal. The two signals then return to the optical fiber coupler and are collected by the integrated spectrometer. Then, the physical thickness and refractive index of the sample A to be tested are calculated by a computer. Specific embodiment 2:

[0079] The present disclosure also provides an embodiment:

[0080] Based on specific embodiment 1, the present disclosure further provides a measurement method, including: receiving a broadband light source and dividing the broadband light source into a first input light source and a second input light source; using the first input light source and the second input light source, respectively measuring a sample A to be measured through a first measuring unit 201 and a second measuring mechanism 202 to obtain a confocal signal and an interference signal, and transmitting the confocal signal and the interference signal to the optical fiber coupling unit 1 to obtain a sum signal of the confocal signal and the interference signal; collecting the sum signal, and obtaining the confocal thickness and optical thickness of the sample A to be measured based on the sum signal; and obtaining the physical thickness and refractive index of the sample A to be measured based on the confocal thickness and the optical thickness.

[0081] Specifically, during one acquisition, the signal collected by the sensor integrated spectrometer is the sum of the confocal signal and the interference signal, which can be expressed as:

[0082]

[0083] Where λ is the wavelength of the broadband light source; M represents the number of surfaces of the sample being measured, so when measuring thin films, M = 2; d conf0 , ɑ and b are the parameters of the dispersive confocal probe; I0 and I1 are the light intensities reflected from the front and back surfaces of the sample film, respectively; φ j0 represents the initial phase of the interference signal; d int Represents the optical thickness of the sample film. The left side of the multiplication sign in formula (1) indicates that the confocal signal is a low-frequency signal formed by the superposition of two sinc() functions. Since M = 2 when measuring thin films, the corresponding λ1 and λ2 are the wavelengths corresponding to the confocal signal peaks. Unlike other optical probes that focus light of different wavelengths on the same plane during chromatic aberration correction, the dispersive confocal probe can focus light of different wavelengths at different depths during chromatic aberration correction design, which makes the confocal depth related to the wavelength. In this method, the relationship between the confocal depth and wavelength can be expressed as: d conf (λ)=bλ+d conf0, so the confocal depths d of the front and back surfaces of the thin film can be determined by finding the peak wavelengths λ1 and λ2. conf1 and d conf2 , so the confocal thickness of the thin film is: d conf = d conf1 - d conf2 . The right side of the multiplication sign in equation (1) represents the interference signal, which is a high-frequency signal. Since this method uses Fourier domain OCT, according to the principle of Fourier domain OCT, every surface inside the sample will cause a frequency in the interference signal, and this frequency f k = d int / π is proportional to the optical depth. Also, because the interference signal is the self-interference of the front and back surfaces of the thin film, as long as the frequency of the Fourier transform of the collected interference signal is determined, the optical thickness of the thin film can be known, that is, the d corresponding to this frequency int is the optical thickness of the thin film; k is the wave number.

[0084] As can be seen from equation (1), the signal collected by the sensor is composed of a low-frequency confocal signal and a high-frequency interference signal. The confocal signal and the interference signal can be separated from the original collected signal by filtering, and the peak wavelength of the confocal signal in the spectral domain and the peak frequency of the interference signal in the frequency domain can be found. Thus, the confocal thickness and the optical thickness of the thin film can be obtained. Through the relationship between the physical thickness, the confocal thickness, and the optical thickness, the physical thickness d of the thin film can be calculated:

[0085]

[0086] where NA is the numerical aperture of the chromatic confocal probe CCP. Since the refractive index n = d int / d, this enables the refractive index of the thin film to be calculated after obtaining the physical thickness and the optical thickness of the thin film.

[0087] Verification step:

[0088] To verify the feasibility of the system described in specific embodiment 1 and the method described in specific embodiment 2, a real system was built according to the optical path structure diagram of the spectral confocal interference sensor system of the dual-channel single spectrometer.

[0089] First, the numerical aperture NA = 0.28 of the chromatic confocal probe selected by the spectral confocal interference sensor system of the dual-channel single spectrometer was used to measure a PET thin film marked as 0.3 mm. The signal collected by the sensor is as Figure 2 (a) shown, Figure 2 (b) and (c) are respectively the confocal signal separated from the original signal using low-pass filtering and the self-interference signal of the front and back surfaces of the thin film separated using high-pass filtering, Figure 2(d) is the result of performing a Fourier transform on the interference signal. Since self-interference of the front and back surfaces of the thin film is adopted in this system, the optical path difference between the two beams of light reflected from the upper and lower surfaces of the thin film is fixed. According to the interference principle, the interference signal frequency generated by this fixed optical path difference is also fixed. Therefore, after Fourier transform, only one peak corresponding to the interference frequency generated by this fixed optical path difference will appear in the frequency domain.

[0090] To determine the relationships among the confocal depth, wavelength, optical thickness, and interference frequency, a calibration experiment was conducted. By translating a 0.3 mm PET film along the depth direction by 100 μm each time, and collecting spectral signals using a spectral confocal interference sensor each time it was moved, and by analyzing the spectral signals collected each time to find the peak wavelength of the confocal signal, it can be seen that the confocal depth and wavelength show a linear relationship. After linear fitting, the relationship formula between the confocal depth and wavelength can be obtained as: d conf (λ) = 0.02967×λ - 20.0784. Since the interference signal frequency of the same thin film measured by the spectral confocal interference sensor of the dual-channel single spectrometer remains unchanged, some semi-transparent samples with known thickness and refractive index were used for calibration. These samples with known thickness and refractive index were successively placed under the dispersion confocal coherence sensor to collect spectral signals, and the interference frequencies of these samples were obtained by analyzing the collected spectral signals. It can be seen that there is a linear relationship between the optical thickness and the interference frequency. After linear fitting, the relationship formula between the optical thickness and the interference frequency can be obtained as: d int = 0.0013×f - 0.0159.

[0091] Subsequently, a commercial OCT system - OQ LabScope 2.0 (with a central wavelength of 840 nm, a depth resolution of 5 μm, and a signal-to-noise ratio of 100 dB) was used to measure the true thickness and refractive index of the 0.3 mm PET film. The specific method was to sandwich the film to be measured between two glass slides and press them tightly, as Figure 3 (a) shows. And place its measured cross-section under the commercial OCT system for imaging. The imaging cross-section result of the film is as Figure 3 (b) shows. Using a measuring tool to measure the film cross-section, the true thickness of the 0.3 mm PET film was obtained as 0.290 mm, and the refractive index was 1.542.

[0092] After calibration, the spectral signals of the 0.3 mm PET film collected by the spectral confocal interference sensor were analyzed. The confocal signal was obtained by low-pass filtering, and the confocal depth of the film could be known by finding the peak wavelength of the confocal signal, thereby obtaining the confocal thickness of the film; the interference signal was obtained by high-pass filtering, and the interference frequency of the interference signal was obtained by performing a Fourier transform on the interference signal, thereby obtaining the optical thickness of the film. The obtained confocal thickness d of the filmconf and the optical thickness d int Substitute into formula (2), and the physical thickness of the thin film can be obtained. Then, the refractive index of the thin film can be calculated based on the optical thickness. The measurement results of the 0.3 mm PET thin film are shown in Table 1 below.

[0093] Table 1: Measurement Results of 0.3 mm PET Thin Film

[0094] Specific Embodiment 3:

[0096] The present disclosure also provides an embodiment:

[0097] An electronic device for thickness measurement, comprising: a storage medium and a processing unit; wherein, the storage medium is used to store a computer program; the processing unit exchanges data with the storage medium and is used to execute the computer program through the processing unit when measuring the thickness of a thin film, and perform the steps of the measurement method as described above.

[0098] The above-mentioned processing unit can perform various appropriate actions and processes according to the program stored in the storage medium. The electronic device further includes the following peripheral devices, including an input part such as a keyboard and a mouse, and may also include an output part such as a cathode ray tube (CRT), a liquid crystal display (LCD), etc. and a speaker.

[0099] The present disclosure also provides an embodiment:

[0100] A readable storage medium: The readable storage medium stores a computer program; when the computer program runs, it executes the steps of the measurement method as described in Specific Embodiment 2.

[0101] In this embodiment, the computer-readable storage medium can be any tangible medium that contains or stores a program, and this program can be used by or in combination with an instruction execution system, device, or component. In the present disclosure, the computer-readable signal medium may include a data signal propagated in a baseband or as part of a carrier wave, which carries the computer-readable program code. Such a propagated data signal can take various forms, including but not limited to electromagnetic signals, optical signals, or any suitable combination of the above. The computer-readable signal medium can also be any computer-readable medium other than the computer-readable storage medium, and this computer-readable medium can send, propagate, or transmit a program for use by or in combination with an instruction execution system, device, or component. The program code contained on the computer-readable medium can be transmitted by any appropriate medium, including but not limited to: wireless, wire, optical cable, RF, etc., or any suitable combination of the above.

[0102] The above are only several specific implementation scenarios of the present disclosure. However, the present disclosure is not limited thereto, and any changes that can be conceived by those skilled in the art should fall within the protection scope of the present disclosure. The above serial numbers of the present disclosure are only for description and do not represent the advantages or disadvantages of the implementation scenarios.

Claims

1. A spectral confocal interference measurement system based on a dual-channel single spectrometer, characterized in that, Comprising: An optical fiber coupling unit for receiving a broadband light source and generating a first input light source and a second input light source by equally dividing the broadband light source; A measurement component optically connected to the optical fiber coupling unit for simultaneously measuring a sample to be measured through the first input light source and the second input light source, respectively obtaining a confocal signal and an interference signal, and transmitting the confocal signal and the interference signal to the optical fiber coupling unit to obtain an added signal of the confocal signal and the interference signal; A first processing unit for performing data interaction with the optical fiber coupling unit to collect the added signal; A second processing unit for performing data interaction with the first processing unit to obtain the confocal thickness and the optical thickness of the sample to be measured according to the added signal; and further obtaining the physical thickness and the refractive index of the sample to be measured according to the confocal thickness and the optical thickness.

2. The spectral confocal interference measurement system based on a dual-channel single spectrometer according to claim 1, wherein The measurement component includes: A first measurement unit connected to the optical fiber coupling unit for measuring the sample to be measured using the first input light source to obtain a confocal signal; A second measurement mechanism connected to the optical fiber coupling unit for measuring the sample to be measured using the second input light source to obtain an interference signal; The first measurement unit and the second measurement mechanism perform data interaction with the optical fiber coupling unit to transmit the confocal signal and the interference signal to the optical fiber coupling unit to obtain an added signal of the confocal signal and the interference signal.

3. The spectral confocal interference measurement system based on a dual-channel single spectrometer according to claim 2, wherein The second measurement mechanism includes: An interference optical unit connected to the optical fiber coupling unit for receiving the second input light source; A first beam splitter disposed at the output end of the interference optical unit; A second beam splitter disposed in parallel with the first beam splitter and located above the sample to be measured.

4. A measurement method based on the measurement system according to any one of claims 1-3, characterized in that, Comprising: Receiving a broadband light source and generating a first input light source and a second input light source by equally dividing the broadband light source; Simultaneously measuring the sample to be measured through the first input light source and the second input light source respectively by a first measurement unit and a second measurement mechanism, respectively obtaining a confocal signal and an interference signal, and transmitting the confocal signal and the interference signal to the optical fiber coupling unit to obtain an added signal of the confocal signal and the interference signal; Collecting the added signal and obtaining the confocal thickness and the optical thickness of the sample to be measured according to the added signal; Obtaining the physical thickness and the refractive index of the sample to be measured according to the confocal thickness and the optical thickness.

5. The measuring method according to claim 4, characterized in that, The simultaneous measurement of the sample to be measured to obtain an added signal of the confocal signal and the interference signal includes: The collected confocal signal and the interference signal are added to form the added signal, expressed as: where λ is the wavelength of the broadband light source; M represents the number of surfaces of the sample under test; d conf0 , α, and b are relevant parameters of the first measurement unit and the second measurement mechanism; I0 and I1 are the light intensities reflected from the front and back surfaces of the sample to be measured, respectively; φ j0 represents the initial phase of the interference signal; d int represents the optical thickness of the sample to be measured; And obtaining the confocal thickness and the optical thickness of the sample to be measured according to the formula of the added signal.

6. The measuring method according to claim 5, characterized in that The obtaining of the confocal thickness and the optical thickness of the sample to be measured according to the formula of the added signal includes: Set the relationship between the confocal depth and the wavelength as: d conf (λ) = bλ + d conf0 ; Determine the confocal depths d of the front and back surfaces of the sample to be measured by finding the peak wavelengths λ1 and λ2 conf1 and d conf2 , and the obtained confocal thickness is: d conf = d conf1 - d conf2 ; Each surface present inside the sample to be measured will result in a frequency in the interference signal, and this frequency f k = d int / π is proportional to the optical depth, and the optical thickness of the sample to be measured is obtained based on the frequency of the Fourier transform of the collected interference signal; k is the wave number.

7. The measurement method according to claim 5, characterized in that The obtaining of the physical thickness of the sample to be measured according to the confocal thickness and the optical thickness includes: Obtaining the physical thickness d of the sample to be measured through the following formula: where NA is the numerical aperture of the chromatic confocal probe CCP; d conf is the confocal thickness of the sample to be measured; d int is the optical thickness of the sample to be measured.

8. The measuring method according to claim 5, characterized in that, The method for obtaining the refractive index of the sample to be measured includes: The refractive index n of the sample to be measured is: n = d int / d; where d int is the optical thickness of the sample to be measured; d is the physical thickness of the sample to be measured.

9. An electronic device for thickness measurement, characterized in that, Comprising: A storage medium for storing a computer program; A processing unit, which exchanges data with the storage medium, is configured to execute the computer program through the processing unit when measuring the film thickness, and perform the steps of the measuring method according to any one of claims 5-8.

10. A readable storage medium, characterized in that: The readable storage medium stores a computer program; When the computer program runs, it performs the steps of the measuring method according to any one of claims 5-8.

Images