Wide-spectrum polarization reflectivity measuring system
By designing a wide-spectrum polarized reflectance measurement system and utilizing optimized optical paths and components, the existing technology's problems of insufficient sensitivity and low accuracy in wide-spectrum and warped sample measurements have been solved, and high-accuracy polarized reflectance measurements have been achieved. .
Patent Information
- Application Number
- CN202411514962.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-29
- Publication Date
- 2025-01-21
AI Technical Summary
Existing optical measurement devices are difficult to achieve high sensitivity and low noise in a wide spectral range, and cannot effectively adapt to warping the sample to be measured, resulting in the accuracy of the measurement results being affected.
A wide -spectrum polarization reflectivity measurement system is designed. By installing the combination of a platform, light source, transmission component, and spectrometer, components such as transmission modules, polarizing modules, and microscopic mirrors are optimized to adapt to wide spectrals and warp samples, and and warpage samples, and also, and samples, and samples, and samples, and samples,,, will also use it. Optimize the light path by calibrating the component to improve the accuracy of measurement.
The high accuracy of the polarizing reflectance measurement results of the murtocal sample under the wide spectrum range is realized, the sensitivity and signal -to -noise ratio of the measurement device are improved, and the light measurement of different bands is adapted to the measurement device.
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Figure CN119334909A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of optical measurement equipment, and in particular to a wide spectrum polarization reflectivity measurement system. Background Art
[0002] Polarized reflectivity reflects the optical properties of the sample to be tested, including transparency, reflection characteristics and optical quality. This is crucial for evaluating the quality and performance of the sample to be tested, and is also an important basis for optimizing the sample preparation process and improving its performance.
[0003] As the spectrum of light output by the light source becomes wider and wider, such as 370nm-2500nm, the intensity of light signals of different wavelengths varies greatly within the wide spectrum range, requiring the measurement device to have high sensitivity and low noise level. However, due to the complex optical path design of existing measurement devices, if they are to be adapted to the wide spectrum range, it is necessary to constantly replace the components of the measurement device. Even so, there may be problems of insufficient sensitivity or low signal-to-noise ratio in certain bands, affecting the accuracy of the measurement results. In addition, when the light within the wide spectrum range interacts with the sample to be tested, it is affected by the surface flatness of the sample to be tested. For example, if the sample to be tested is a warped sample to be tested, complex absorption, scattering and reflection phenomena will occur on the warped sample to be tested, increasing the complexity and uncertainty of the measurement.
[0004] Therefore, it is urgent to develop new measurement devices to adapt to the warped samples under a wide spectral range. Summary of the invention
[0005] In order to improve the accuracy of the polarization reflectivity of a sample to be measured in a wide spectral range, the present application provides a wide spectrum polarization reflectivity measurement system.
[0006] In a first aspect of the present application, a wide spectrum polarization reflectivity measurement system is provided. The measurement system comprises: A mounting table for placing the sample to be tested; A light source, for providing incident light; A transmission component, comprising a transmission module, a polarization module and a microscope objective lens, wherein the transmission module comprises a first semi-transparent and semi-reflective mirror and a second semi-transparent and semi-reflective mirror, wherein the second semi-transparent and semi-reflective mirror is used to reflect the incident light onto the sample to be tested, and the polarization module and the microscope objective lens are sequentially arranged on an optical path between the second semi-transparent and semi-reflective mirror and the sample to be tested; A spectrometer, wherein the light collecting direction of the spectrometer is arranged toward the first output light path of the first semi-transparent and semi-reflective mirror.
[0007] By adopting the above technical solution, the sample to be tested is first placed on the mounting table, and the light source provides incident light, and the incident light passes through the second semi-transparent and semi-reflective mirror, the polarization module and the microscope objective lens in sequence to reach the sample to be tested. Then, the incident light is reflected as reflected light through the sample to be tested, and the reflected light passes through the microscope objective lens, the polarization module and the second semi-transparent and semi-reflective mirror in sequence to reach the first semi-transparent and semi-reflective mirror. At this time, the reflected light is reflected again by the first semi-transparent and semi-reflective mirror, and part of the light enters the spectrometer from the first output optical path, so as to facilitate the subsequent calculation of the polarization reflectivity of the sample to be tested according to the intensity of the reflected light received by the spectrometer. Since the optical path of the measurement system of the present application can be adjusted by the transmission component, for example, the propagation path of the light can be changed by the transmission module, and the azimuth angle of the incident light irradiated on the sample to be tested can be changed by the polarization module, and the polarization reflectivity corresponding to each curved surface of the warped sample to be tested in different bands can be measured by adopting a microscope objective lens adapted to a wide spectral range, thereby improving the accuracy of the measurement result of the polarization reflectivity of the warped sample to be tested.
[0008] In a possible implementation: further comprising a calibration component, the calibration component comprising a cross-reticle and an image sensor; The cross-reticle is arranged on the optical path between the light source and the second semi-transparent and semi-reflective mirror; The collection end of the image sensor is arranged toward the second output light path of the first semi-transparent and semi-reflective mirror. The second output light path and the first output light path are two light paths with different directions in which reflected light is output from the first semi-transparent and semi-reflective mirror. The reflected light is light formed after the incident light is reflected by the sample to be tested.
[0009] By adopting the above technical solution, before using the measurement system, the optical path in the measurement system can also be calibrated through the calibration component. Specifically, the sample to be measured is first placed on the mounting table, and the light source provides incident light. The incident light presents a cross shape after passing through the cross-shaped graticule, and the cross-shaped incident light then passes through the second semi-transparent and semi-reflective mirror and the polarization module in sequence before reaching the sample to be measured. The cross-shaped incident light is reflected by the sample to be measured and becomes reflected light, and the reflected light also presents a cross shape. Then, the cross-shaped reflected light passes through the microscope objective, the polarization module, and the second semi-transparent and semi-reflective mirror in sequence to reach the first semi-transparent and semi-reflective mirror. The reflected light is reflected again after passing through the first semi-transparent and semi-reflective mirror, and part of the light is transmitted to the image sensor from the second output optical path. The image sensor can determine whether the pitch state of the sample to be tested meets the calibration requirements based on whether the cross shape of the received incident light meets the preset shape requirements, so as to continuously optimize the optical path in the measurement system, and then facilitate the subsequent measurement of the polarization reflectivity of the warped sample to be tested for incident light of different bands under the optimized optical path, thereby ensuring the accuracy of the obtained polarization reflectivity.
[0010] In a possible implementation manner, a frosted glass is provided on a side of the cross-reticle facing the light source.
[0011] By adopting the above technical solution, the frosted glass can evenly irradiate the incident light on the cross-shaped reticle plate, thereby making the cross-shaped incident light passing through the cross-shaped reticle plate more uniform, thereby ensuring the accuracy of the cross-shaped reflected light received by the image sensor.
[0012] In a possible implementation manner, the image sensor is one of a charge coupled device image sensor and a complementary metal oxide semiconductor.
[0013] In a possible implementation manner: an aperture is provided on the second output light path of the first semi-transparent and semi-reflective mirror.
[0014] By adopting the above technical solution, the interference light contained in the reflected light is shielded by the aperture to ensure the reliability of the transmitted reflected light.
[0015] In a possible implementation: the transmission component further includes a collimator lens; The collimator is arranged on the optical path between the cross-reticle plate and the light source.
[0016] By adopting the above technical solution, the collimator is used to ensure that the incident light output by the light source is parallel light, so that the incident light irradiated onto the cross-shaped graticule is more uniform, further ensuring the accuracy of the cross-shaped reflected light received by the image sensor.
[0017] In a possible implementation, the mounting platform is provided with knobs for adjusting the sample to be tested along the X, Y, and Z axes.
[0018] In a possible implementation manner, a light absorbing hole is opened on the mounting platform, and the area of the mounting platform irradiated by the incident light coincides with the area of the mounting platform occupied by the light absorbing hole.
[0019] By adopting the above technical solution and setting the light absorption hole, when the incident light irradiates the sample to be tested, the light transmitted by the sample to be tested is absorbed by the light absorption hole, thereby preventing the transmitted light from being reflected on the mounting table and interfering with the reflected light.
[0020] In summary, the present application includes at least one of the following beneficial technical effects: On the one hand, before using the measurement system, the optical path in the measurement system is calibrated first, specifically: first place the sample to be measured on the mounting table, and the light source provides incident light. The incident light presents a cross shape after passing through the cross-shaped graticule, and the cross-shaped incident light then passes through the second semi-transparent and semi-reflective mirror, the polarization module, and the microscope objective lens in sequence before reaching the sample to be measured. The cross-shaped incident light is reflected by the sample to be measured and becomes reflected light, and the reflected light is also in a cross shape. Then, the cross-shaped reflected light passes through the microscope objective lens, the polarization module, and the second semi-transparent and semi-reflective mirror in sequence before reaching the first semi-transparent and semi-reflective mirror. The reflected light is reflected again after passing through the first semi-transparent and semi-reflective mirror, and part of the light is transmitted from the second output optical path to the image sensor. The image sensor can determine whether the pitch state of the sample to be measured meets the calibration requirements based on whether the cross shape of the received incident light meets the preset shape requirements, thereby optimizing the optical path in the measurement system. On the other hand, based on the optical path in the optimized measurement system, the incident light propagates along the same optical path, and the obtained reflected light also propagates along the same optical path. The difference is that when the reflected light passes through the first semi-transparent and semi-reflective mirror, part of the light enters the spectrometer from the first output optical path, which is convenient for the subsequent calculation of the polarization reflectivity of the sample to be measured based on the intensity of the reflected light received by the spectrometer. Moreover, when the optical path is optimized, the measurement system of the present application can adapt to light sources with a wide spectral range, thereby ensuring the accuracy of the measured polarization reflectivity. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 It is a schematic diagram of the structure of a wide spectrum polarization reflectivity measurement system when measuring polarization reflectivity.
[0022] Figure 2 It is a schematic diagram of the structure of the wide spectrum polarization reflectivity measurement system when calibrating the sample to be measured.
[0023] Explanation of the accompanying drawings: 1. Mounting table; 2. Light source; 3. Collimating mirror; 4. First semi-transparent and semi-reflective mirror; 5. Second semi-transparent and semi-reflective mirror; 6. Polarization module; 7. Microscope objective; 8. Spectrometer; 9. Server; 10. Frosted glass; 11. Cross-reticle; 12. Image sensor; 13. Optical fiber; 14. Aperture. DETAILED DESCRIPTION
[0024] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.
[0025] The sample to be tested is a sample that has been specially processed, such as polishing, coating, etc., to achieve a mirror-like imaging effect on its surface, which can reflect the surrounding scenery and form a clear image. Due to the different usage scenarios of different samples to be tested, the samples to be tested may be regular and flat, or irregular and warped.
[0026] When measuring the polarization reflectivity of the sample to be tested, in order to better understand the optical properties of the sample to be tested, a light source 2 with a wide spectral range is often provided, and the light source 2 provides light of the corresponding wavelength band for the sample to be tested according to actual needs. In order to adapt to the measurement of the polarization reflectivity of the sample to be tested under light of different wavelength bands, the present application proposes a wide spectrum polarization reflectivity measurement system.
[0027] like Figure 1 and Figure 2 As shown, the wide spectrum polarization reflectivity measurement system includes a mounting platform 1, a light source 2, a transmission component, a spectrometer 8 and a calibration component. Among them, the mounting platform 1, the light source 2, the transmission component and the spectrometer 8 are used together to measure the polarization reflectivity of the sample to be measured, and the mounting platform 1, the light source 2, the transmission component and the calibration component are used together to calibrate the optical path in the measurement system, so as to better measure the polarization reflectivity of the sample to be measured under light of different wavelength bands in the subsequent measurement. It should be noted that Figure 1 and Figure 2 The direction of the arrow indicates the direction of light propagation.
[0028] The sample to be tested is placed on the mounting table 1, which is provided with knobs for adjusting the sample to be tested along the X, Y, and Z axes. The pitch state of the sample to be tested is adjusted by adjusting the knobs of the X, Y, and Z axes. At the same time, a manual adjustment knob is provided for manually and automatically adjusting the pitch state of the sample to be tested. The manual adjustment knob realizes the adjustment function by driving the X, Y, and Z axes through a vacuum adsorption pump. In addition, a light absorption hole is provided on the mounting table 1, and the light absorption hole is located below the sample to be tested. In other examples, other structures can be provided to place the sample to be tested.
[0029] The light source 2 is one of a deuterium lamp and a tungsten lamp, and is used to provide incident light with a wide spectral range for the sample to be tested. In order to reduce the loss of the incident light, an optical fiber 13 is provided at the output end of the light source 2, and the incident light is transmitted to the transmission component by the optical fiber 13.
[0030] Along the incident direction of the incident light, the transmission component includes a collimator 3, a transmission module, a polarization module 6 and a microscope objective 7 in sequence. The microscope objective 7 can be replaced by a collimator.
[0031] The transmission module includes a first semi-transparent mirror 4 and a second semi-transparent mirror 5. The first semi-transparent mirror 4 and the second semi-transparent mirror 5 can be semi-transparent mirrors of the same type, or semi-transparent mirrors of different types. The types of semi-transparent mirrors include ultraviolet semi-transparent mirrors, visible segment semi-transparent mirrors, near-infrared semi-transparent mirrors, etc. Among them, the second semi-transparent mirror 5 is used to reflect the incident light onto the sample to be tested. In order to control the different azimuths of the incident light irradiated on the sample to be tested, a polarization module 6 is arranged on the light path between the second semi-transparent mirror 5 and the sample to be tested, and the polarization module 6 is one of a polarizing prism and a polarizing plate. It should be noted that no matter whether a polarizing prism or a polarizing plate is selected, it is required to be able to adapt to incident light in a wide spectral range.
[0032] The microscope objective lens 7 is arranged on the optical path between the polarization module 6 and the sample to be tested. In a specific example, when the microscope objective lens 7 is used, the microscope objective lens 7 is a microscope objective lens 7 with a replaceable magnification, the magnification is between 15 times and 40 times, and the distance between the microscope objective lens 7 and the sample to be tested is 23.8 mm, and the sample to be tested is 7.8 mm.
[0033] In addition, an aperture 14 is provided on the rear focal plane of the microscope objective 7 to block the interference light reflected by the table surface of the mounting table 1 and the interference light reflected by the non-measurement area of the sample to be measured, thereby improving the reliability of the reflected light in the optical path.
[0034] The spectrometer 8 is one of a grating spectrometer and a scanning spectrometer. The light collecting direction of the spectrometer 8 is set toward the first output light path of the first semi-transparent and semi-reflective mirror 4. Specifically, the spectrometer 8 is connected with an optical fiber 13, and the end of the optical fiber 13 away from the spectrometer 8 is set on the second output light path of the first semi-transparent and semi-reflective mirror 4 to reduce the loss of light entering the spectrometer 8. The spectrometer 8 is externally connected to a server 9, and a computing model is configured in the server 9. The computing model is a neural network model obtained by pre-training. The computing model can calculate the polarization reflectivity of the sample to be tested according to the intensity of the light collected by the spectrometer 8.
[0035] The calibration component includes a frosted glass 10, a cross-reticle plate 11 and an image sensor 12. The frosted glass 10 and the cross-reticle plate 11 are arranged between the collimator 3 and the second semi-transparent and semi-reflective mirror 5, the frosted glass 10 is close to the side where the collimator 3 is arranged, and the cross-reticle plate 11 is close to the side where the second semi-transparent and semi-reflective mirror 5 is arranged. Specifically, the frosted glass 10 and the cross-reticle plate 11 are arranged close to each other, and the frosted glass 10 is used to make the incident light uniform, so that the incident light is evenly irradiated on the cross-reticle plate 11. The cross-reticle plate 11 can use a transparent background combined with a black crosshair or a black background combined with a transparent crosshair. In this example, the cross-reticle plate 11 uses a black background combined with a transparent crosshair as an example, that is, after the incident light is irradiated on the cross-reticle plate 11, only the area of the transparent crosshair passes the incident light, and other areas block the propagation of the incident light. In other words, the incident light output after the incident light passes through the cross-reticle plate 11 presents a cross shape.
[0036] The image sensor 12 is one of a charge coupled device (CCD) image sensor and a complementary metal-oxide-semiconductor (CMOS). The acquisition end of the image sensor 12 is arranged toward the second output light path of the first semi-transparent and semi-reflective mirror 4. It should be noted that the first output light path and the second output light path are two light paths in different directions output by the reflected light from the first semi-transparent and semi-reflective mirror 4, and the reflected light is the light formed after the incident light is reflected by the sample to be tested.
[0037] It should be noted that before using the above-mentioned wide spectrum polarization reflectivity measurement system to measure the polarization reflectivity of the sample to be measured, it is necessary to first calibrate the optical path in the wide spectrum polarization reflectivity measurement system. The specific calibration process is shown in steps S1 to S7: Step S1: placing the sample to be tested on the mounting platform 1. Specifically, the sample to be tested is placed above the light absorption hole, and the area where the sample to be tested contacts the mounting platform 1 is larger than the area where the light absorption hole is located on the mounting platform 1, thereby preventing the sample to be tested from falling into the light absorption hole. At the same time, it is ensured that the area where the incident light irradiates the mounting platform 1 coincides with the area where the light absorption hole occupies the mounting platform 1, and the micro-area sample to be tested is located directly above the light absorption hole, so that when the incident light irradiates the micro-area sample to be tested, the light transmitted by the micro-area sample is absorbed by the light absorption hole, thereby preventing the transmitted light from being reflected on the mounting platform 1 and interfering with the reflected light.
[0038] Step S2: The light source 2 provides incident light, which passes through the collimator 3, the frosted glass 10, the cross-shaped plate 11, the second semi-transparent and semi-reflective mirror 5, the polarization module 6, and the microscope objective 7 in sequence to reach the sample to be tested. The incident light after passing through the cross-shaped plate 11 presents a cross shape, so the incident light irradiated to the sample to be tested also presents a cross shape.
[0039] Step S3: The incident light is reflected by the sample to be tested and becomes reflected light, and the reflected light passes through the microscope objective 7, polarization module 6, second semi-transparent mirror 5 and reaches the first semi-transparent mirror 4. Among them, after the cross-shaped incident light is reflected by the sample to be tested, the obtained reflected light still presents a cross shape.
[0040] Step S4: The reflected light is reflected again by the first semi-transparent mirror 4, and part of the light is transmitted from the second output optical path to the image sensor 12. After the reflected light passes through the second semi-transparent mirror 5, part of the light enters the spectrometer 8 from the first output optical path, and the remaining part of the light enters the image sensor 12 from the second output optical path.
[0041] Step S5: The image sensor 12 determines whether the cross received through the second output light path coincides with the preset cross. First, a preliminary test is performed: when the incident light is reflected by the sample to be tested, the reflected light formed can enter the spectrometer 8 from the first output light path and the intensity is maximum, the shape, size, position and other information of the cross received in the image sensor 12, and the cross at this time is saved to complete the calibration. Therefore, before measuring the polarization reflectivity of the sample to be tested, it is necessary to verify whether the optical path is normal based on the cross obtained by the preliminary test, specifically to determine whether the cross formed by the reflected light reflected by the sample to be tested in the image sensor 12 coincides with the calibrated cross.
[0042] Step S6: If yes, the sample to be tested has completed the verification.
[0043] Step S7: If not, adjust the knobs for adjusting the sample to be tested along the X, Y, and Z axes until the cross shape received through the second output light path coincides with the preset cross shape.
[0044] It should be noted that each time before using the above measurement system, the sample to be tested needs to be calibrated according to the above steps. After the calibration is completed, it means that the optical path of the measurement system is normal and the loss of reflected light is minimal, so multiple samples to be tested can be measured continuously during the measurement without performing a calibration operation for each sample to be tested.
[0045] Based on the calibrated wide spectrum polarization reflectivity measurement system, the measurement process is as follows: First, the sample to be tested is placed on the mounting table 1, specifically, the sample to be tested is placed directly above the light absorption hole, and the light source 2 provides incident light, and the incident light passes through the collimator 3, the second semi-transparent and semi-reflective mirror 5, the polarization module 6, and the microscope objective 7 in sequence to reach the sample to be tested. The incident light is reflected as reflected light by the sample to be tested, and the reflected light passes through the microscope objective 7, the polarization module 6, and the second semi-transparent and semi-reflective mirror 5 in sequence to reach the first semi-transparent and semi-reflective mirror 4. Then, the reflected light is reflected again by the first semi-transparent and semi-reflective mirror 4, and part of the light is transmitted from the first output optical path to the spectrometer 8, and the spectrometer 8 transmits the intensity of the collected reflected light to the server 9, and the server 9 uses a calculation model to analyze the intensity of the reflected light to obtain the polarization reflectivity, and the remaining light is transmitted from the second output optical path to the image sensor 12.
[0046] It should be noted that if the response of the spectrometer 8 in some bands is low, the spectrometer 8 will use variable gain and increased averaging times in this band to achieve signal-to-noise ratio balance in the entire band to improve the accuracy of the intensity of the obtained reflected light.
[0047] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of disclosure involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the aforementioned disclosed concept. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) by each other to form a technical solution.
Claims
1. A wide spectrum polarization reflectivity measurement system, characterized in that: include: A mounting table (1) for placing a sample to be tested; A light source (2) for providing incident light; A transmission component, comprising a transmission module, a polarization module (6) and a microscope objective lens (7), wherein the transmission module comprises a first semi-transparent and semi-reflective mirror (4) and a second semi-transparent and semi-reflective mirror (5), wherein the second semi-transparent and semi-reflective mirror (5) is used to reflect the incident light onto the sample to be tested, and the polarization module (6) and the microscope objective lens (7) are sequentially arranged on an optical path between the second semi-transparent and semi-reflective mirror (5) and the sample to be tested; A spectrometer (8), wherein the light collecting direction of the spectrometer (8) is arranged toward the first output light path of the first semi-transparent and semi-reflective mirror (4).
2. The wide spectrum polarization reflectivity measurement system according to claim 1, characterized in that: Also included is a calibration component, the calibration component comprising a cross-reticle plate (11) and an image sensor (12); The cross-reticle plate (11) is arranged on the optical path between the light source (2) and the second semi-transparent and semi-reflective mirror (5); The collection end of the image sensor (12) is arranged toward the second output light path of the first semi-transparent and semi-reflective mirror (4); the second output light path and the first output light path are two light paths in different directions in which reflected light is output from the first semi-transparent and semi-reflective mirror (4); the reflected light is light formed after the incident light is reflected by the sample to be measured.
3. The wide spectrum polarization reflectivity measurement system according to claim 2, characterized in that: A frosted glass (10) is provided on the side of the cross-reticle plate (11) facing the light source (2).
4. The wide spectrum polarization reflectivity measurement system according to claim 2, characterized in that: The image sensor (12) is one of a charge coupled device image sensor and a complementary metal oxide semiconductor.
5. The wide spectrum polarization reflectivity measurement system according to claim 2, characterized in that: A stop (14) is provided on the second output light path of the first semi-transparent and semi-reflective mirror (4).
6. The wide spectrum polarization reflectivity measurement system according to claim 2, characterized in that: The transmission component also includes a collimator (3); The collimator (3) is arranged on the optical path between the cross-reticle plate (11) and the light source (2).
7. The wide spectrum polarization reflectivity measurement system according to claim 1, characterized in that: The mounting platform (1) is provided with knobs for adjusting the sample to be tested along the X, Y and Z axes.
8. The wide spectrum polarization reflectivity measurement system according to claim 1, characterized in that: A light absorbing hole is provided on the mounting platform (1), and the area of the mounting platform (1) irradiated by the incident light coincides with the area of the mounting platform (1) occupied by the light absorbing hole.