A micro-optical dispersion measurement system and method based on dark-field scattering

Abstract

The application belongs to the technical field of optical measurement, and discloses a micro area optical dispersion measurement system and method based on dark field scattering, which comprises a sample stage, an oblique incidence excitation module and a dark field collection module; the wide spectrum light output by the oblique incidence excitation module forms parallel light oblique incidence and irradiates on the sample; the dark field collection module comprises, from bottom to top, a collection objective, a first lens, a pinhole diaphragm, a second lens, a moving mechanism, a third lens and a spectrometer which are sequentially arranged above the sample; the sample is located at the front focal plane of the collection objective, the distance between the back focal plane of the collection objective and the first lens is equal to the focal length of the first lens, and the distance between the first lens and the slit is equal to the focal length of the first lens; the distance between the slit and the second lens is equal to the focal length of the second lens, and the distance between the third lens and the spectrometer is equal to the focal length of the third lens; the second lens is arranged in the light path of the dark field collection module through the moving mechanism, and the application avoids interference and improves the measurement precision through dark field scattering.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of optical measurement, and particularly relates to a micro-area optical dispersion measurement system and method based on dark-field scattering. BACKGROUND

[0002] The dispersion relation is a key parameter that describes the relationship between the propagation characteristics (such as wavelength, frequency) and energy or momentum of waves. For photonic crystals, metasurfaces and other micro-nano structures, the dispersion relation not only determines the propagation behavior of light, but also affects the localization characteristics of light. Therefore, accurately measuring the dispersion relation of these materials is an important step in designing and optimizing micro-nano photonic devices.

[0003] In recent years, with the rapid development of micro-nano processing technology and optical detection technology, the demand for accurate measurement of the dispersion relation of micro-area materials has increased. In particular, in the field of micro-nano photonic devices and material characterization, researchers often need to perform high-precision dispersion relation measurement and analysis on a micrometer scale. However, traditional dispersion measurement methods usually rely on complex optical systems and require a large measurement range, which makes it difficult to achieve rapid measurement in micro-area in actual operation. In addition, traditional dispersion measurement methods use light reflection or transmission to achieve measurement, and the measurement process usually relies on the interaction of surface or bulk light with matter. In reflection or transmission mode, the incident light inevitably interferes with the collected signal, often resulting in a large amount of background noise and non-intrinsic information in the signal, which cannot directly characterize the intrinsic state of the sample. This interference limits the understanding and analysis of the true optical properties of the material.

[0004] In order to meet this demand, it is particularly important to develop a micro-area optical dispersion measurement system that is simple in structure, high in integration, and accurate in measurement. SUMMARY

[0005] In order to solve the technical problem that the optical dispersion of the micro-area of the sample is difficult to accurately measure in the prior art, the present application proposes a micro-area optical dispersion measurement system and method based on dark-field scattering, which obtains sample information through the scattering effect of the incident light on the sample, and effectively eliminates the interference of the incident light mode using the dark-field scattering signal, thereby more accurately and directly characterizing the intrinsic state of the sample.

[0006] In order to solve the above technical problems, the technical scheme adopted by the present application is as follows: a micro-area optical dispersion measurement system based on dark-field scattering, comprising: a sample stage, an oblique incidence excitation module and a dark-field collection module; the sample stage is used for placing a sample;

[0007] The oblique incidence excitation module comprises a wide-spectrum illumination light source and a lens group; the wide-spectrum light output by the wide-spectrum illumination light source forms parallel light after passing through the lens group and is obliquely incident on the sample;

[0008] The dark field collection module comprises, from bottom to top, a collection objective, a first lens, a pinhole diaphragm, a second lens, a moving mechanism, a third lens and a spectrometer, which are arranged above the sample in sequence and the optical axis direction is perpendicular to the sample; the sample is located at the front focal plane of the collection objective, the distance between the back focal plane of the collection objective and the first lens is equal to the focal length of the first lens, and the distance between the first lens and the pinhole diaphragm is equal to the focal length of the first lens; the distance between the pinhole diaphragm and the second lens is equal to the focal length of the second lens, and the distance between the third lens and the spectrometer is equal to the focal length of the third lens; the second lens is arranged in the light path of the dark field collection module through the moving mechanism, and the moving mechanism is used to drive the second lens to be placed in or out of the light path of the dark field collection module.

[0009] The wide-spectrum illumination light source is a halogen lamp, a xenon lamp or an ultra-continuous white light source, and the spectrometer is a surface array spectrometer.

[0010] The dark field collection light path further comprises a polarization detection device, the polarization detection device is used to adjust the polarization of the collected scattered light, and the sample stage is a three-dimensional adjusting mechanism.

[0011] The polarization detection device comprises a polaroid and a quarter-wave plate, the Stokes parameter is obtained by adjusting the optical axis angle of the polaroid and the quarter-wave plate, and then the polarization state of the scattered light signal can be obtained.

[0012] The lens group comprises a fourth lens, a fifth lens and an illumination objective, and the wide-spectrum light output by the wide-spectrum illumination light source is sequentially incident on the sample stage through the fourth lens, the fifth lens and the illumination objective, the distance between the wide-spectrum illumination light source and the fourth lens is equal to the focal length of the fourth lens, and the distance between the fifth lens and the back focal plane of the illumination objective is equal to the distance of the fifth lens.

[0013] The wide-spectrum light output by the wide-spectrum illumination light source forms parallel light after passing through the lens group, and is obliquely incident on the sample stage at an incident angle of 0°.

[0014] The moving mechanism is a linear motor, and the motion direction is perpendicular to the light path of the dark field collection module.

[0015] In addition, the application also provides a micro-area optical dispersion measurement method based on dark field scattering, which is realized based on the micro-area optical dispersion measurement system based on dark field scattering and comprises the following steps:

[0016] Step one: control the moving mechanism to place the second lens in the light path of the dark field collection module, control the spectrometer slit to be fully opened and the grating to be modulated at zero level, adjust the spectrometer to imaging mode, select appropriate exposure time, fine-tune the distance between the sample and the dark field collection module until the image is clear, adjust the sample position to align the region to be measured of the sample with the center of the pinhole diaphragm, finally, adjust the aperture size of the pinhole diaphragm to adjust the imaging area, and then adjust the spectrometer slit to match the region to be measured of the sample, and then collect the sample topography image through the spectrometer.

[0017] Step two: control the moving mechanism to remove the second lens from the light path of the dark field collection module, adjust the spectrometer to spectrum measurement mode, and then adjust the center wavelength of the grating of the spectrometer to the wavelength to be measured, and then collect the sample dispersion spectrum through the spectrometer.

[0018] The micro-area optical dispersion measurement method based on dark field scattering further comprises a step of calibrating the pixel resolution of the spectrometer, and the specific method is as follows:

[0019] A transmission grating with a known grating constant d is arranged on the sample stage, the laser is incident on the transmission grating, the moving mechanism is controlled to remove the second lens from the light path of the dark field collection module, the spectrometer is adjusted to spectrum measurement mode, the transmission spectrum of the transmission grating is measured, and the corresponding pixel number ΔY of the distance between the zero-order stripe and the first-order stripe after the transmission grating is determined; the pixel resolution M of the spectrometer is calculated, and the calculation formula is as follows:

[0020]

[0021] dsinθ=mλ;

[0022] Wherein, d represents the grating constant, θ represents the diffraction angle, λ represents the wavelength, and m represents the grating order, m=1.

[0023] The micro-area optical dispersion measurement method based on dark field scattering further comprises a step of adjusting the sample direction to be the same as the direction of the spectrometer slit, and a step of arranging a polarization device in the light path of the dark field collection module and adjusting the angle of the polarization device to improve the energy band clarity.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] 1. The present application provides a micro-area optical dispersion measurement system and method based on dark field scattering, which uses the scattering effect of the sample on the incident light to obtain sample information, and can be used to measure the energy band structure, band gap properties and dispersion relationship of micro-nano structures. Compared with the reflection signal, the dark field scattering signal effectively eliminates the interference of the incident light mode, thereby more accurately and directly representing the intrinsic state of the sample. The present application can provide more intrinsic data without introducing additional interference, and can accurately measure the dispersion relationship of micro-area materials.

[0026] 2、The wide spectrum illumination light source of the application adopts an oblique incidence excitation mode, according to the reflection law of light, reflected light cannot enter the collection light path, only the scattered light of the sample surface enters the collection light path, the interference of the excitation light mode is avoided, and the sample intrinsic state is more conducive to characterization; at the same time, the dark field mode is more conducive to observing the morphology of small particles on the sample surface, and the sample imaging resolution is significantly improved, therefore, the application has the advantages of high optical path structure integration, high measurement accuracy and simplified measurement process.

[0027] 3、The wide spectrum illumination light source adopted by the application, such as a halogen lamp, a xenon lamp and an ultra-continuous white light source, enables the system to obtain the optical characteristics of the sample at multiple wavelengths at one time, reduces the need for multiple measurements and improves experimental efficiency. The application greatly improves the accuracy and efficiency of optical dispersion measurement, and has important scientific research value and practical application prospect in many fields such as material science and semiconductor manufacturing. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 A micro-area optical dispersion measurement system optical path schematic diagram based on a dark field scattering is provided for the first embodiment of the application;

[0029] Figure 2 An optical path schematic diagram in the imaging mode is provided for the second embodiment of the application;

[0030] Figure 3 An optical path schematic diagram in the spectrum measurement mode is provided for the second embodiment of the application;

[0031] Figure 4 A sample structure schematic diagram is provided for the second embodiment of the application;

[0032] Figure 5 A dispersion relationship diagram of a grating along the KY direction collected in the second embodiment of the application;

[0033] In the figure: 1-wide spectrum illumination light source, 2-fourth lens, 3-fifth lens, 4-illumination objective lens, 5-sample stage, 6-sample, 7-collection objective lens, 8-first lens, 9-small aperture diaphragm, 10-polarization device, 11-second lens, 12-third lens, 13-area array spectrometer, 14-moving mechanism. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the embodiments of the application more clear, the technical scheme in the embodiments of the application will be described clearly and completely below, obviously, the described embodiments are part of the embodiments of the application, rather than all the embodiments; based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0035] Embodiment one

[0036] As Figure 1 shown, the embodiment one of the present application provides a micro-area optical dispersion measurement system based on dark-field scattering, comprising: a sample stage 5, an oblique incidence excitation module and a dark-field collection module; the sample stage 5 is used for placing a sample 6.

[0037] Specifically, in the embodiment, the oblique incidence excitation module comprises a wide-spectrum illumination light source 1 and a lens group; the wide-spectrum light output by the wide-spectrum illumination light source 1 forms parallel light after passing through the lens group and is obliquely incident on the sample.

[0038] Specifically, in the embodiment, the dark-field collection module comprises, from bottom to top, a collection objective 7, a first lens 8, a pinhole diaphragm 9, a second lens 11, a moving mechanism, a third lens 12 and a spectrometer 13 which are sequentially arranged above the sample and have an optical axis direction perpendicular to the sample; the sample is located at the front focal plane of the collection objective 7, the distance between the back focal plane of the collection objective 7 and the first lens 8 is equal to the focal length of the first lens 8, and the distance between the first lens 8 and the pinhole diaphragm 9 is equal to the focal length of the first lens 8; the distance between the pinhole diaphragm 9 and the second lens 11 is equal to the focal length of the second lens 11, and the distance between the third lens 12 and the spectrometer 13 is equal to the focal length of the third lens 12; the second lens 11 is arranged in the light path of the dark-field collection module through the moving mechanism 14, and the moving mechanism 14 is used to drive the second lens 11 to be placed in or out of the light path of the dark-field collection module.

[0039] Specifically, in the embodiment, the wide-spectrum illumination light source 1 is a halogen lamp, a xenon lamp or an ultra-continuous white light source, and the spectrometer 13 is a face array spectrometer.

[0040] Further, in the embodiment, the dark-field collection light path further comprises a polarization detection device 10, which is used to adjust the polarization of the collected scattered light. The sample stage is a three-dimensional adjustment mechanism, through which the three-dimensional position of the sample can be adjusted, the confocal of the sample and the collection objective 7 is realized, and the adjustment of the sample measurement area is realized.

[0041] Further, in the embodiment, the polarization detection device 10 comprises a polaroid and a quarter-wave plate, and the Stokes parameter is obtained by adjusting the optical axis angle of the polaroid and the quarter-wave plate, and then the polarization state of the scattered light signal can be obtained.

[0042] Further, in the embodiment, the lens group comprises a fourth lens 2, a fifth lens 3 and an illumination objective 4, the wide-spectrum light output by the wide-spectrum illumination light source 1 is sequentially obliquely incident on the sample table 5 through the fourth lens 2, the fifth lens 3 and the illumination objective 4, the distance between the wide-spectrum illumination light source 1 and the fourth lens 2 is equal to the focal length of the fourth lens 2, and the distance between the fifth lens 3 and the back focal plane of the illumination objective 4 is equal to the distance of the fifth lens 3. In addition, in the embodiment, the sample is located on the front focal plane of the illumination objective 4, and more illumination light utilization rate can be obtained.

[0043] Further, in the embodiment, the wide-spectrum light output by the wide-spectrum illumination light source 1 forms parallel light after passing through the lens group, and is obliquely incident on the sample table 5 at an incident angle of 30-60°.

[0044] Further, in the embodiment, the moving mechanism 14 is a linear motor, and the motion direction is perpendicular to the optical path of the dark-field collection module.

[0045] The working principle of the embodiment of the application is as follows:

[0046] When the second lens 11 is located in the optical path, the scattered light emitted from a point on the sample 6 located on the front focal plane of the collection objective 7 is converted into parallel light after passing through the collection objective 7, is focused on the plane of the pinhole diaphragm 9, and is focused again on the slit of the spectrometer 13 through the second lens 11 and the third lens 12; the zero-order of the grating of the spectrometer 13 is cut, the software interface of the spectrometer is set as an imaging mode, and the center of the pinhole diaphragm 9 can be imaged on the center of the CCD of the spectrometer by setting the positions of the second lens 11 and the third lens 12, and meanwhile, the sample can be moved to make the sample region to be measured be imaged on the center of the pinhole diaphragm, that is, the collection of the sample micro-region signal is realized.

[0047] After the second lens 11 is cut out of the optical path, the scattered light in each direction on the sample surface is transformed to be present at different points on the back focal plane through the collection objective 7, and the signals at different points on the back focal plane of the collection objective 7 are refocused on the slit of the spectrometer through the first lens 8 and the third lens 12; the spectrometer is set as a spectrum measurement mode, at this time, the signals perpendicular to the slit of the spectrometer are expanded along the wavelength, and the signals in the direction parallel to the slit of the spectrometer still carry the angle information of the back focal plane, and thus the dispersion spectrum of the sample scattered signal is obtained.

[0048] In the embodiment, the sample region is determined by the aperture-adjustable pinhole diaphragm 9 and the slit of the spectrometer 13, and the reason is that the pinhole diaphragm 9 and the slit of the spectrometer 13 are both located on the sample confocal plane, and for the micro-nano structure, the pinhole diaphragm 9 functions as a field diaphragm, and can select the sample micro-region in the CCD when the collection optical path is imaging, and the influence of the signals in the region other than the micro-region to be measured is reduced.

[0049] Embodiment two

[0050] Embodiment 2 of the present invention provides a micro-area optical dispersion measurement method based on dark field scattering, which is implemented based on the micro-area optical dispersion measurement system based on dark field scattering described in Embodiment 1, and includes the following steps:

[0051] Step 1: Control the moving mechanism to place the second lens 11 in the optical path of the dark field collection module, control the slit of the spectrometer 13 to be fully opened and the grating to be modulated to zero order, adjust the spectrometer 13 to imaging mode, select an appropriate exposure time, fine-tune the distance between the sample and the dark field collection module until the image is clear, and at the same time adjust the sample position so that the sample area to be measured is aligned with the center of the pinhole aperture 9; finally, adjust the aperture size of the pinhole aperture 9 to adjust the imaging area so that it matches the sample area to be measured, adjust the slit of the spectrometer 13, and acquire the sample morphology image through the spectrometer 13.

[0052] like Figure 2 As shown, when the second lens 11 is placed in the optical path of the dark field collection module, the system is in imaging mode. The sample surface information is reproduced for the first time at the pinhole aperture 9 through the transformation of the collection objective lens 7 and the first lens 8, and then imaged again at the slit position of the spectrometer 13 by the second lens 11 and the third lens 12. Under the premise of determining the center position of the spectrometer array, the image of the pinhole aperture 9 is adjusted to the center of the spectrometer array by fine-tuning the two-dimensional frame on which the second lens 11 is installed. Then, a suitable exposure time for the CCD is selected, and the position of the sample stage along the optical axis is finely adjusted to obtain a clear image of the sample. The sample area to be measured is adjusted by adjusting the sample stage so that it is imaged to the center of the pinhole aperture 9. Finally, the aperture size of the pinhole aperture 9 is adjusted to match the size of the sample area to be measured as much as possible, and the slit of the spectrometer is reduced to improve the measurement accuracy while reducing the influence of stray light.

[0053] Step 2: Control the moving mechanism to make the second lens 11 leave the optical path of the dark field collection module, adjust the spectrometer 13 to the spectral measurement mode, and at the same time adjust the center wavelength of the grating of the spectrometer 13 to the band to be measured, and collect the sample dispersion spectrum through the spectrometer 13.

[0054] like Figure 3 As shown, when the second lens 11 leaves the optical path of the dark field collection module, the system is in momentum space acquisition mode. The momentum space information of the back focal plane of the collection objective lens 7 is transformed into parallel light by the first lens 8, and then focused at the slit of the spectrometer 13 by the third lens 12. The center wavelength of the grating of the spectrometer 13 is modulated to the band to be measured. Due to dispersion, the grating will perform wavelength expansion on the light perpendicular to the direction of the spectrometer slit. At the same time, under the combined action of the first lens 8 and the third lens 12, the slit of the spectrometer 13 and the back focal plane of the collection objective lens 7 are in a conjugate state, and both contain the angular information of the sample scattered light. The momentum space angular information along the slit direction is preserved. Thus, the wavelength-angle information of the scattered light of the micro-area sample, i.e., the dispersive spectrum, can be obtained by the spectrometer.

[0055] In the embodiment, the spectral angle resolution is determined by the NA value of the second objective lens (7) and the magnification of the third lens (8) and the fifth lens (12), and before formal measurement, the pixel resolution of the spectrometer needs to be calibrated first. Further, the micro-area optical dispersion measurement method based on dark-field scattering of the embodiment further comprises the step of calibrating the pixel resolution of the spectrometer, and the specific method is as follows:

[0056] A transmission grating with a known grating constant d is arranged on the sample stage, the laser is incident on the transmission grating, the moving mechanism is controlled to make the second lens 11 leave the optical path of the dark-field collection module, the spectrometer 13 is adjusted to the spectrum measurement mode, the transmission spectrum of the transmission grating is measured, and the corresponding pixel number ΔY of the distance between the zero-order stripe and the first-order stripe after the transmission grating is determined; the pixel resolution M of the spectrometer is calculated, and the calculation formula is:

[0057]

[0058] dsinθ=mλ; (2)

[0059] Wherein, d represents the grating constant, θ represents the diffraction angle, λ represents the wavelength, m represents the grating diffraction order, and m=1.

[0060] Further, the micro-area optical dispersion measurement method based on dark-field scattering of the embodiment further comprises the step of adjusting the sample direction to make the KY direction the same as the slit direction of the spectrometer.

[0061] Further, the micro-area optical dispersion measurement method based on dark-field scattering of the embodiment further comprises the step of arranging a polarization device in the optical path of the dark-field collection module and adjusting the angle of the polarization device to improve the energy band clarity. In addition, by adjusting the angle between the polarization plate and the optical axis of the quarter-wave plate, the Stokes parameters can be calculated according to the light intensity at different angles, and then the polarization state of the scattered light signal can be obtained.

[0062] Specifically, in the embodiment, a PMMA grating on a 1cm×1cm ITO glass made by EBL process is placed on the sample stage, the period is 400nm, the grating line width is 240nm, the grating area size is 40μm×40μm, the thickness of TiO2 layer and PMMA is 60nm, and the sample structure schematic diagram is as shown in Figure 4The specific manufacturing process is as follows: first, a 60nm-thick TiO2 layer is plated on the ITO glass by using a plating machine; second, 60nm PMMA is spin-coated by controlling the spin-coating speed and time; then, the area outside the grating line is exposed by using an electron beam, and the solubility of the PMMA in the area bombarded by the electron beam will change; finally, the grating structure is obtained after developing and fixing. The TiO2 acts as a waveguide, and the one-dimensional grating structure of PMMA is used to regulate the Brillouin zone light field. Here, by adjusting the sample direction, the sample KY direction is adjusted to be consistent with the spectrometer slit, and the angle of the polarizer in the detection polarization device 10 is adjusted to the clearest measured energy band, which can improve the resolution and filter out the interference of the required energy band.

[0063] As shown in Figure 5 The dispersion relationship diagram of the grating along the KY direction measured by the application is shown in the figure.

[0064] In summary, the application provides a micro-area optical dispersion measurement system and method based on dark-field scattering, which uses the scattering effect of the sample on the incident light to obtain sample information, and can be used to measure the energy band structure, band gap properties, dispersion relationship, etc. of the micro-nano structure. Compared with the reflection signal, the dark-field scattering signal effectively eliminates the interference of the incident light mode, thereby more accurately and directly characterizing the intrinsic state of the sample. The application can provide more intrinsic data without introducing additional interference, and can accurately measure the dispersion relationship of the micro-area material.

[0065] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the application, and not to limit them; although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A micro-area optical dispersion measurement system based on dark field scattering, characterized in that, include: Sample stage, oblique incidence excitation module and dark field collection module; The sample stage is used to place samples; The oblique incidence excitation module includes a broadband illumination source (1) and a lens group; The broadband light output from the broadband illumination source (1) is parallel light that is obliquely incident on the sample after passing through the lens group; The dark field collection module includes, from bottom to top, a collection objective (7), a first lens (8), a pinhole aperture (9), a second lens (11), a moving mechanism, a third lens (12), and a spectrometer (13), arranged above the sample with their optical axes perpendicular to the sample. The sample is located at the front focal plane of the collection objective (7). The distance between the rear focal plane of the collection objective (7) and the first lens (8) is equal to the focal length of the first lens (8). The distance between the first lens (8) and the pinhole aperture (9) is equal to the focal length of the first lens (8). The distance between the pinhole aperture (9) and the second lens (11) is equal to the focal length of the second lens (11). The distance between the third lens (12) and the spectrometer (13) is equal to the focal length of the third lens (12). The second lens (11) is positioned in the optical path of the dark field collection module via the moving mechanism (14). The moving mechanism is used to drive the second lens (11) to be placed in or away from the optical path of the dark field collection module. The lens group includes a fourth lens (2), a fifth lens (3) and an illumination objective (4). The broadband light output by the broadband illumination source (1) is obliquely incident on the sample stage (5) through the fourth lens (2), the fifth lens (3) and the illumination objective (4) in sequence. The distance between the broadband illumination source (1) and the fourth lens (2) is equal to the focal length of the fourth lens (2), and the distance between the fifth lens (3) and the back focal plane of the illumination objective (4) is equal to the focal length of the fifth lens (3).

2. The micro-area optical dispersion measurement system based on dark field scattering according to claim 1, characterized in that, The broadband illumination source (1) is a halogen lamp, a xenon lamp, or a supercontinuous white light source, and the spectrometer (13) is an area array spectrometer.

3. The micro-area optical dispersion measurement system based on dark field scattering according to claim 1, characterized in that, The optical path of the dark field collection module also includes a polarization analyzer (10), which is used to adjust the polarization of the collected scattered light. The sample stage is a three-dimensional adjustment mechanism.

4. The micro-area optical dispersion measurement system based on dark field scattering according to claim 3, characterized in that, The polarization analyzer (10) includes a polarizer and a quarter-wave plate, used to measure the polarization state of the scattered light signal.

5. The micro-area optical dispersion measurement system based on dark field scattering according to claim 1, characterized in that, The broadband light output from the broadband illumination source (1) is parallel light after passing through the lens group and is obliquely incident on the sample stage (5) at an incident angle of 30-60°.

6. The micro-area optical dispersion measurement system based on dark field scattering according to claim 1, characterized in that, The moving mechanism is a linear motor, and its direction of movement is perpendicular to the optical path of the dark field collection module.

7. A method for measuring micro-area optical dispersion based on dark-field scattering, implemented based on the micro-area optical dispersion measurement system based on dark-field scattering as described in claim 1, characterized in that, Includes the following steps: Step 1: Control the moving mechanism to place the second lens (11) in the optical path of the dark field collection module, control the slit of the spectrometer (13) to be fully opened and the grating to be modulated to zero order, adjust the spectrometer (13) to imaging mode, select an appropriate exposure time, fine-tune the distance between the sample and the dark field collection module until the image is clear, and at the same time adjust the sample position so that the sample area to be tested is aligned with the center of the pinhole aperture (9); finally, adjust the aperture size of the pinhole aperture (9) to adjust the imaging area so that it matches the sample area to be tested, adjust the slit of the spectrometer (13), and collect the sample morphology image through the spectrometer (13); Step 2: Control the moving mechanism to make the second lens (11) leave the optical path of the dark field collection module, adjust the spectrometer (13) to the spectral measurement mode, and at the same time adjust the center wavelength of the grating of the spectrometer (13) to the band to be measured, and collect the sample dispersion spectrum through the spectrometer (13).

8. The micro-area optical dispersion measurement method based on dark field scattering according to claim 7, characterized in that, It also includes a step of calibrating the pixel resolution of the spectrometer, the specific method of which is as follows: A transmission grating with a known grating constant d is set on the sample stage, and the laser is incident on the transmission grating. The moving mechanism is controlled to make the second lens (11) leave the optical path of the dark field collection module. The spectrometer (13) is adjusted to the spectral measurement mode, and the transmission spectrum of the transmission grating is measured. The number of pixels ΔY corresponding to the distance between the zero-order fringe and the first-order fringe after passing through the transmission grating is determined. The pixel resolution M of the spectrometer is calculated using the following formula: ； ； Where d represents the grating constant. Indicates the diffraction angle. The wavelength is represented by λ, and m represents the grating order, where m = 1.

9. The micro-area optical dispersion measurement method based on dark field scattering according to claim 7, characterized in that, It also includes the steps of adjusting the sample orientation so that its KY direction is the same as the direction of the spectrometer slit, and setting a polarization device in the optical path of the dark field collection module and adjusting the angle of the polarization device to improve the bandgap resolution.

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