A system and method for realizing micro-area spectral measurement

Abstract

This invention discloses a system and method for realizing micro-area spectral measurement, including a reflective microscopic imaging optical path, a transmission spectral testing optical path, and a sample clamping mechanism. By employing a quasi-monochromatic light scanning method for spectral calibration, measurement errors caused by the dispersion of the microscope objective are effectively avoided. An optical climbing frame adjusts the horizontal beam emitted from the light source to a suitable height to match the subsequent microscopic imaging and spectral testing optical paths. The reflective coupling structure used in the reflective microscopic imaging optical path helps to reduce the system's spatial dimensions. The transmitted light collected by the second microscope objective reaches the grating spectrometer only through the transmission fiber, which helps to reduce stray light interference. The sample clamping mechanism enables pitch, deflection, and XYZ direction displacement adjustment of the sample, solving the technical problems of existing measurement systems being unable to detect certain angle-sensitive material structures and having low compatibility.

Description

Technical Field

[0001] This invention belongs to the field of optical microscopy and spectral testing technology, and relates to measurement systems, specifically a system and method for realizing micro-area spectral measurement. Background Technology

[0002] With the continuous development of artificial micro / nano photonic materials such as photonic crystals, surface plasmons, and metasurfaces, accurate characterization of these materials, given their small size and angular sensitivity, is a crucial aspect of this field. Among these methods, spectroscopic testing, as the gold standard for verifying and analyzing the "fingerprint" of material structure, is a key means of characterizing the structural properties of micro / nano materials. Therefore, the development and verification of accurate and stable micro-area spectroscopic testing systems are essential for the advancement of micro / nano materials.

[0003] Traditional micro-area spectroscopy testing systems primarily utilize commercial microscopes. To ensure the system's optical resolution, the numerical aperture of the light collection path is typically very large. When detecting samples at micro- and nano-scales, the signal-to-noise ratio is often very low, making it difficult to distinguish between signal and background light. Furthermore, the displacement structure of this type of system usually cannot achieve adjustments in dimensions such as pitch and deflection, making it difficult to detect certain angle-sensitive material structures. Additionally, the overall system is complex, expensive, has low compatibility, and incurs extremely high costs for modification and testing.

[0004] Therefore, this invention designs and constructs an experimental system capable of micro-area spectral measurement. This system is characterized by its ease of operation, reasonable assembly and adjustment, low cost, and strong scalability, providing a feasible solution for spectral testing of micro-area samples. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a system and method for realizing micro-area spectral measurement, thereby solving the technical problems of existing measurement systems being unable to detect certain angle-sensitive material structures and having low compatibility.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A system for realizing micro-area spectral measurement includes a reflective microscopic imaging optical path, a transmissive spectral testing optical path, and a sample clamping mechanism; the reflective microscopic imaging optical path includes a light source module, a lens module, and an image processing module arranged sequentially; the transmissive spectral testing optical path includes a light collection module, a coupling module, and a spectral analysis module arranged sequentially.

[0008] The light source module includes a fiber optic halogen light source, a monochromator is coupled to the fiber optic halogen light source, and a first collimating lens and an optical climbing frame are sequentially arranged after the monochromator; a movable first reflecting mirror and a second reflecting mirror are arranged on the optical climbing frame.

[0009] The lens module includes a coaxial aperture and a beam splitter prism arranged sequentially in the reflected light path of the second mirror. Below the beam splitter prism is a first coaxial displacement structure, on which a first microscope objective is fixedly mounted. Above the beam splitter prism are a second coaxial displacement structure and a third coaxial displacement structure arranged sequentially. A second collimating lens is fixedly mounted on the second coaxial displacement structure, and a third collimating lens is fixedly mounted on the third coaxial displacement structure. The first microscope objective, the beam splitter prism, the second collimating lens, and the third collimating lens are coaxial in the vertical direction.

[0010] The image processing module includes an image sensor and a computer connected together, wherein the image sensor and the third collimating lens are coaxial in the vertical direction;

[0011] The light collection module includes a second microscope objective confocal with the first microscope objective and a fourth coaxial displacement structure for fixing the second microscope objective;

[0012] The coupling module includes a concave reflector, a coaxial fiber optic bracket, and a fiber optic adapter fixed on the coaxial fiber optic bracket; the center of the concave reflector is coaxial with the second microscope objective and the fiber optic adapter in the vertical and horizontal directions, respectively.

[0013] The spectral analysis module includes a transmission optical fiber connected at one end to the optical fiber adapter, and a grating spectrometer connected at the other end of the transmission optical fiber.

[0014] The sample clamping mechanism includes a six-axis displacement stage and a sample clamp fixed on the six-axis displacement stage.

[0015] This invention also includes the following technical features:

[0016] Both the second and third collimating lenses are achromatic lenses, and their combined focal length is mm.

[0017] The beam splitter prism has a beam splitting ratio of 1:1; the first microscope objective has a magnification of 50.

[0018] The first coaxial displacement structure, the second coaxial displacement structure, and the third coaxial displacement structure are all two-dimensional displacement adjustment structures.

[0019] The fourth coaxial displacement structure is a five-dimensional displacement adjustment structure.

[0020] A method for achieving micro-area spectral measurement, using the aforementioned system for achieving micro-area spectral measurement, specifically includes the following steps:

[0021] Step 1: Set the monochromator scanning wavelength range and scanning step size, thereby determining the monochromator scanning wavelength point as M, and setting the number of data points detected by the grating spectrometer as N;

[0022] Step 2: Adjust the six-axis displacement stage so that the sample to be tested is deviated from the focal point of the beam;

[0023] Step 3: Measure the spectral matrix T1 of the substrate of the sample to be tested. ij ;

[0024] in:

[0025] i = 1, 2, ..., M, representing the i-th scanning wavelength point of monochromator 2;

[0026] j = 1, 2, ..., N, representing the spectral resolution of the grating spectrometer 23;

[0027] Step four: Move the six-axis displacement stage so that the sample under test is coaxial with the focal point of the beam, and measure the transmission spectrum matrix T2 of the sample under test. ij ;

[0028] Step 5, combine the spectral matrix T1 obtained in Step 3. ij and the transmission spectrum matrix T2 obtained in step five ij Substituting into the following formula, we obtain the spectral curve T of the sample to be tested;

[0029]

[0030] Where T is a 1×N vector.

[0031] Compared with the prior art, the beneficial technical effects of this invention are:

[0032] (I) In this invention, spectral calibration is performed using a quasi-monochromatic light scanning method, which effectively avoids measurement errors caused by the dispersion of the microscope objective. The optical climbing frame adjusts the horizontal beam emitted from the light source to a suitable height to match the subsequent microscopic imaging optical path and spectral testing optical path. The numerical aperture of the second microscope objective matches that of the first microscope objective, and the two are confocal, which minimizes non-signal crosstalk and facilitates maximum beam collection, thereby improving the signal-to-noise ratio of the system's spectral detection. The reflective coupling structure used in the reflective microscopic imaging optical path helps to reduce the system's spatial size. The transmitted light collected by the second microscope objective reaches the grating spectrometer only through the transmission fiber, which helps to reduce stray light interference. The sample clamping mechanism enables pitch, deflection, and XYZ direction displacement adjustment of the sample, solving the technical problem that the existing measurement system is difficult to detect certain angle-sensitive material structures and has low compatibility.

[0033] (II) The illumination in this invention adopts a Köhler illumination optical path structure. The image of the light source is located at the front focal plane of the second microscope objective 17, so only parallel beams are incident on the sample plane. The light source does not converge to form an image on the sample, thus the illumination is uniform. After passing through the sample plane, the illumination light is imaged on the rear focal plane of the second collimating lens 10, which is located between the second collimating lens 10 and the third collimating lens 11. The image of the light source is not formed on the image sensor 12, so it does not affect the image quality. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the main structure of a system capable of micro-area spectral measurement;

[0035] Figure 2(a) is a schematic diagram of the optical path near the sample to be tested;

[0036] Figure 2(b) is a schematic diagram of the transverse light distribution on the surface of the high signal-to-noise ratio test sample;

[0037] Figure 2(c) is a schematic diagram of the transverse light distribution on the surface of the high signal-to-noise ratio test sample;

[0038] Figure 3 This is the illumination optical path diagram in this invention;

[0039] Figure 4 This is the optical path diagram for microscopic observation in this invention;

[0040] Figure 5 This is the optical path diagram for spectral measurement in this invention.

[0041] The labels in the diagram represent the following: 1-Fiber optic halogen light source, 2-Monochromator, 3-First collimating lens, 4-Optical climbing frame, 5-First reflecting mirror, 6-Second reflecting mirror, 7-Coaxial aperture, 8-Beam splitter prism, 9-First microscope objective, 10-Second collimating lens, 11-Third collimating lens, 12-Image sensor, 13-Computer, 14-First coaxial displacement structure, 15-Second coaxial displacement structure, 16-Third coaxial displacement structure, 17-Second microscope objective, 18-Fourth coaxial displacement structure, 19-Concave reflecting mirror, 20-Coaxial fiber optic fixture, 21-Fiber optic adapter, 22-Transmission fiber, 23-Grating spectrometer, 24-Six-axis displacement stage, 25-Sample holder.

[0042] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0043] It should be noted that, unless otherwise specified, all components in this invention are those known in the art.

[0044] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0045] A system for realizing micro-area spectral measurement includes a reflective microscopic imaging optical path, a transmissive spectral testing optical path, and a sample clamping mechanism; the reflective microscopic imaging optical path includes a light source module, a lens module, and an image processing module arranged in sequence; the transmissive spectral testing optical path includes a light collection module, a coupling module, and a spectral analysis module arranged in sequence.

[0046] The light source module includes an optical fiber halogen light source 1, a monochromator 2 is coupled to the optical fiber halogen light source 1, and a first collimating lens 3 and an optical climbing frame 4 are arranged sequentially after the monochromator 2; a movable first reflecting mirror 5 and a second reflecting mirror 6 are arranged on the optical climbing frame 4.

[0047] The lens module includes a coaxial aperture 7 and a beam splitter prism 8 arranged sequentially on the reflected light path of the second reflector 6. A first coaxial displacement structure 14 is arranged below the beam splitter prism 8, and a first microscope objective 9 is fixedly arranged on the first coaxial displacement structure 14. A second coaxial displacement structure 15 and a third coaxial displacement structure 16 are arranged sequentially above the beam splitter prism 8. A second collimating lens 10 is fixedly arranged on the second coaxial displacement structure 15, and a third collimating lens 11 is fixedly arranged on the third coaxial displacement structure 16. The first microscope objective 9, the beam splitter prism 8, the second collimating lens 10, and the third collimating lens 11 are coaxial in the vertical direction.

[0048] The image processing module includes an image sensor 12 and a computer 13 connected together. The image sensor 12 and the third collimating lens 11 are coaxial in the vertical direction.

[0049] The light collection module includes a second microscope objective 17 confocal with the first microscope objective 9 and a fourth coaxial displacement structure 18 for fixing the second microscope objective;

[0050] The coupling module includes a concave reflector 19, a coaxial fiber optic bracket 20, and a fiber optic adapter 21 fixed on the coaxial fiber optic bracket 20; the center of the concave reflector 19 is coaxial with the second microscope objective 17 and the fiber optic adapter 21 in the vertical and horizontal directions, respectively.

[0051] The spectral analysis module includes a transmission optical fiber 22 connected at one end to the optical fiber adapter 21, and a grating spectrometer 23 connected at the other end of the transmission optical fiber 22.

[0052] The sample clamping mechanism includes a six-axis displacement stage 24 and a sample clamp 25 fixed on the six-axis displacement stage 24.

[0053] When using the above technical solution, firstly, the sample to be tested is placed on the sample holder 25, the fiber optic spectrometer 23 is replaced with a fiber optic halogen light source 1, and the fourth coaxial displacement structure 18 is adjusted until a bright field of view is observed at the image sensor 12. This fully utilizes the numerical aperture of the first microscope objective 9, maximizing the observation field of view and facilitating the search for micro / nano samples. The illumination optical path is shown in Figure 2. The point light source is emitted from the fiber optic adapter 21, converges through the concave mirror 19 to the back focal plane of the second microscope objective 17, and then illuminates the sample surface with parallel light, passing sequentially through the first microscope objective 9, the beam splitter prism 8, the second collimating lens 10, and the third collimating lens 11, finally reaching the point image sensor 12. The entire illumination adopts a Köhler illumination optical path structure. Its advantage is that the image of the light source is located at the front focal plane of the second microscope objective 17, so only parallel beams are incident on the sample plane, and the light source does not converge on the sample to form an image, thus the illumination is uniform. Secondly, after the illumination light passes through the sample plane, it is imaged on the back focal plane of the second collimating lens 10. This position is between the second collimating lens 10 and the third collimating lens 11. The light source image is not formed on the image sensor 12, so it will not affect the image quality.

[0054] Then, adjust the six-axis displacement stage 24 to perform a large-scale scan of the sample surface. After moving the sample to the center of the observation screen, connect and position the fiber optic halogen light source 1 and the fiber optic spectrometer 23 according to the original system structure. The microscopic optical path is as follows: Figure 4 As shown. Turn on the fiber optic halogen light source 1, adjust the position of the output fiber head, and simultaneously observe the light intensity change at the output end of the monochromator 2. When the output light intensity of the monochromator 2 reaches its maximum, fix the position of the output fiber head of the fiber optic halogen light source to complete the coupling of the spatial optical path. The light modulated by the monochromator 2 becomes parallel light after passing through the first collimating lens 3, and is subsequently reflected and elevated by the first reflecting mirror 5 and the second reflecting mirror 6. After the horizontal collimated light passes through the coaxial aperture 7 and is perpendicularly incident on the beam splitter prism 8, a portion becomes vertically downward collimated light, which is then focused onto the sample by the first microscope objective 9. The reflected light focused on the sample is collected by the first microscope objective 9, passes vertically upward through the beam splitter prism 8, and is then received by the image sensor 12 after passing through the second collimating lens 10 and the third collimating lens 11.

[0055] Finally, the six-axis stage 24 is finely adjusted so that the focal point of the first microscope objective 9 is precisely positioned on the micro / nano sample. To avoid measurement errors caused by the angle sensitivity of the sample and to determine the geometric relationship between the sample surface and the incident light, the following operations are required:

[0056] S1, adjust the vertical knob of the six-axis displacement stage 24 to observe the elliptical ring in the image sensor 12 that changes with the movement, and fix the vertical position;

[0057] S2, adjust the rotation and pitch knobs of the six-axis displacement stage 24, observe the shape of the light spot collected in the image sensor, and at the same time adjust the vertical direction knob. When the shape of the light spot does not change with the change of the vertical knob, fix the rotation and pitch knobs.

[0058] S3, adjust the vertical knob of the six-axis displacement stage 24 and fix it to another vertical position, then repeat S2;

[0059] S4, finally adjust the emitted light from the first microscope objective 9 to be perpendicular to the surface of the sample to be tested.

[0060] Spectral measurement optical path as follows Figure 5 As shown. The incident light through the first microscope objective 9 is incident perpendicularly onto the sample surface. The fourth coaxial displacement structure 18 is adjusted so that the focal point of the second microscope objective 17 coincides with the sample. At this time, the light transmitted through the sample is collected by the second microscope objective 17, reflected and focused by the concave mirror 19, and finally received and coupled with the fiber optic adapter 21.

[0061] Furthermore, by employing a quasi-monochromatic light scanning method for spectral calibration, measurement errors caused by the dispersion of the microscope objectives are effectively avoided. The optical climbing frame adjusts the horizontal beam emitted from the light source to a suitable height to match the subsequent microscopic imaging optical path and spectral testing optical path. The numerical aperture of the second microscope objective matches that of the first microscope objective, and the two are confocal, minimizing non-signal crosstalk and facilitating maximum beam collection, thereby improving the signal-to-noise ratio of the system's spectral detection. The reflective coupling structure used in the reflective microscopic imaging optical path helps to reduce the system's spatial size. The transmitted light collected by the second microscope objective reaches the grating spectrometer only through the transmission fiber, which helps to reduce stray light interference. The sample clamping mechanism enables pitch, deflection, and XYZ direction displacement adjustment of the sample, solving the technical problem of existing measurement systems being unable to detect certain angle-sensitive material structures and having low compatibility.

[0062] The image sensor uses an industrial monochrome camera. The industrial monochrome camera's detection array has no special filters, which can maximize the detection intensity to ensure that each monochromatic light incident on the observation image.

[0063] Specifically, the second collimating lens 10 and the third collimating lens 11 are both achromatic lenses, and their combined focal length is 180mm.

[0064] Specifically, the beam splitter prism 8 has a beam splitting ratio of 1:1; the first microscope objective 9 has a magnification of 50. The beam splitting ratio and magnification can be selected according to specific circumstances.

[0065] Specifically, the first coaxial displacement structure 14, the second coaxial displacement structure 15, and the third coaxial displacement structure 16 are all two-dimensional displacement adjustment structures, which enable both the second collimating lens and the third collimating lens to achieve two-dimensional displacement adjustment, that is, to achieve adjustment in the XY direction, which facilitates the collimation adjustment of the coaxial beam and makes the image located at the center of the CCD.

[0066] Specifically, the fourth coaxial displacement structure is a five-dimensional displacement adjustment structure, which enables the second microscope objective to achieve five-axis displacement adjustment, namely pitch, deflection and XYZ direction adjustment, which is beneficial for beam collection and subsequent mechanical adjustment of beam coupling.

[0067] A method for achieving micro-area spectral measurement, employing a system capable of micro-area spectral measurement, specifically includes the following steps:

[0068] Step 1: Set the monochromator scanning wavelength range and scanning step size, thereby determining the monochromator scanning wavelength point as M, and setting the number of data points detected by the grating spectrometer as N;

[0069] Step 2: Adjust the six-axis displacement stage so that the sample to be tested is deviated from the focal point of the beam;

[0070] Step 3: Measure the spectral matrix T1 of the substrate of the sample to be tested. ij ;

[0071] in:

[0072] i = 1, 2, ..., M, representing the i-th scanning wavelength point of monochromator 2;

[0073] j = 1, 2, ..., N, representing the spectral resolution of the grating spectrometer 23;

[0074] Step four: Move the six-axis displacement stage so that the sample under test is coaxial with the focal point of the beam, and measure the transmission spectrum matrix T2 of the sample under test. ij ;

[0075] Step 5, combine the spectral matrix T1 obtained in Step 3. ij and the transmission spectrum matrix T2 obtained in step five ij Substituting into the following formula, we obtain the spectral curve T of the sample to be tested;

[0076]

[0077] Where T is a 1×N vector.

[0078] In the above technical solution, the wavelength range is determined by the fiber optic halogen light source.

Claims

1. A system for enabling micro-spectral measurements, characterized by, It comprises a reflective microscopic imaging light path, a transmissive spectral testing light path and a sample clamping mechanism; the reflective microscopic imaging light path comprises a light source module, a lens module and an image processing module arranged in sequence; the transmissive spectral testing light path comprises a light collecting module, a coupling module and a spectral analysis module arranged in sequence; The light source module comprises a fiber halogen light source (1), a monochromator (2) is coupled and connected to the fiber halogen light source (1), a first collimating lens (3) and an optical climbing frame (4) are sequentially arranged behind the monochromator (2); the optical climbing frame (4) is provided with a movable first reflecting mirror (5) and a second reflecting mirror (6); The lens module comprises a coaxial diaphragm (7) and a beam splitting prism (8) arranged in sequence on the reflected light path of the second reflecting mirror (6), a first coaxial displacement structure (14) is arranged below the beam splitting prism (8), a first microscopic objective lens (9) is fixedly arranged on the first coaxial displacement structure (14), a second coaxial displacement structure (15) and a third coaxial displacement structure (16) are sequentially arranged above the beam splitting prism (8), a second collimating lens (10) is fixedly arranged on the second coaxial displacement structure (15), and a third collimating lens (11) is fixedly arranged on the third coaxial displacement structure (16); the first microscopic objective lens (9), the beam splitting prism (8), the second collimating lens (10) and the third collimating lens (11) are coaxial in the vertical direction; The image processing module comprises an image sensor (12) and a computer (13) connected in sequence, and the image sensor (12) is coaxial with the third collimating lens (11) in the vertical direction; The light collecting module comprises a second microscopic objective lens (17) confocal with the first microscopic objective lens (9) and a fourth coaxial displacement structure (18) for fixing the second microscopic objective lens (17); The coupling module comprises a concave mirror (19), a coaxial optical fiber fixing frame (20) and an optical fiber adapter (21) fixed on the coaxial optical fiber fixing frame (20); the center of the concave mirror (19) is coaxial with the second microscopic objective lens (17) and the optical fiber adapter (21) in the vertical direction and the horizontal direction, respectively; The spectral analysis module comprises a transmission optical fiber (22) connected to one end of the optical fiber adapter (21), and a grating spectrometer (23) connected to the other end of the transmission optical fiber (22); The sample clamping mechanism comprises a six-axis displacement table (24) and a sample clamp (25) fixed on the six-axis displacement table (24).

2. The system capable of microspectral measurement according to claim 1, wherein, The second collimating lens (10) and the third collimating lens (11) are both achromatic lenses, and the combined focal length is 180 mm.

3. The system capable of microspectral measurement according to claim 1, wherein, The beam splitting ratio of the beam splitting prism (8) is 1:1, and the magnification of the first microscopic objective lens (9) is 50.

4. The system capable of microspectral measurement according to claim 1, wherein, The first coaxial displacement structure (14), the second coaxial displacement structure (15) and the third coaxial displacement structure (16) are all two-dimensional displacement adjustment structures.

5. The system according to claim 1, wherein the system is capable of performing microspectrometry. The fourth coaxial displacement structure is a five-dimensional displacement adjustment structure.

6. A method of enabling microspectrometry, characterized by, The system capable of realizing micro-area spectral measurement according to any one of claims 1 to 5, specifically comprising the following steps: Step one, set the monochromator scanning wavelength range and scanning step, and then determine the scanning wavelength point of the monochromator as , and set the data points detected by the grating spectrometer as ; Step two, adjusting the six-axis displacement table so that the sample to be measured deviates from the focus point of the light beam; Step three, measuring the spectral matrix of the sample substrate to be measured ; Wherein: , indicates the first scan wavelength point of the monochromator; , denotes the spectral resolution number of the optical grating spectrometer; Step four, move the six-axis displacement table to make the sample to be measured coaxial with the focal point of the light beam, and measure the transmission spectrum matrix of the sample to be measured ; Step five, the spectral matrix obtained in step three and the transmission spectral matrix obtained in step five is substituted into the following formula to obtain the spectral curve of the sample to be measured ; wherein: is a vector.

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