Micro-area optical dispersion measurement system and method based on dark field scattering

Abstract

The invention belongs to the technical field of optical measurement, and discloses a micro-area optical dispersion measurement system and method based on dark field scattering, and the system 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 to irradiate a sample in an oblique incidence manner; the dark field collection module comprises a collection objective lens, a first lens, a pinhole diaphragm, a second lens, a moving mechanism, a third lens and a spectrograph which are sequentially arranged above the sample from bottom to top; a sample is located at the front focal plane of the collection objective lens, the distance between the rear focal plane of the collection objective lens 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; according to the invention, interference is avoided through dark field scattering, and the measurement precision is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical measurement, and particularly relates to a micro-region optical dispersion measurement system and method based on dark-field scattering, which realizes dispersion measurement by collecting the dark-field scattering signals of a sample micro-region. Background Art

[0002] The dispersion relation is a key parameter that describes the relationship between the propagation characteristics of waves (such as wavelength, frequency) and energy or momentum. For micro-nano structures such as photonic crystals and metasurfaces, the dispersion relation not only determines the propagation behavior of light but also affects the light localization characteristics. Therefore, accurately measuring the dispersion relation of these materials is an important step in the design and optimization of 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-region materials has been increasing. Especially in the fields of micro-nano photonic devices and material characterization, researchers often need to perform high-precision dispersion relation measurement and analysis on the micron scale. However, traditional dispersion measurement methods usually rely on complex optical path systems and require a large measurement range, which is often difficult to achieve rapid micro-region measurement in actual operation. In addition, traditional dispersion measurement methods use light reflection or light transmission to achieve measurement, and the measurement process usually relies on the interaction between surface or bulk light and matter. In the 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, and unable to directly characterize the intrinsic state of the sample. This interference limits the understanding and analysis of the true optical properties of materials.

[0004] To meet this demand, it is particularly important to develop a micro-region optical dispersion measurement system with a simple structure, high integration, and high measurement accuracy. Summary of the Invention

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

[0006] To solve the above technical problem, the technical solution adopted by the present invention is: a micro-region 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 includes a broadband illumination light source and a lens group; the broadband light output by the broadband illumination light source forms parallel light and obliquely irradiates the sample after passing through the lens group;

[0008] The dark-field collection module includes a collection objective lens, 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 from bottom to top with the optical axis direction perpendicular to the sample; the sample is located at the front focal plane of the collection objective lens, the distance between the rear focal plane of the collection objective lens 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 optical 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 optical path of the dark-field collection module.

[0009] The broadband illumination light source is a halogen lamp, a xenon lamp, or a supercontinuum white light source, and the spectrometer is a area array spectrometer.

[0010] The dark-field collection optical path further includes a polarization analyzer, which is used to adjust the polarization of the collected scattered light, and the sample stage is a three-dimensional adjustment mechanism.

[0011] The polarization analyzer includes a polarizer and a quarter-wave plate. By adjusting the optical axis angles of the polarizer and the quarter-wave plate, Stokes parameters are obtained, and then the polarization state of the scattered light signal can be obtained.

[0012] The lens group includes a fourth lens, a fifth lens, and an illumination objective lens. The broadband light output by the broadband illumination light source is obliquely incident on the sample stage through the fourth lens, the fifth lens, and the illumination objective lens in sequence. The distance between the broadband 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 rear focal plane of the illumination objective lens is equal to the focal length of the fifth lens.

[0013] The broadband light output by the broadband 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 -°.

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

[0015] In addition, the present invention also provides a micro-area optical dispersion measurement method based on dark-field scattering, which is implemented based on the above-mentioned micro-area optical dispersion measurement system based on dark-field scattering, and includes the following steps:

[0016] Step 1: Control the moving mechanism to place the second lens in the optical path of the dark-field collection module. Completely open the spectrometer slit and modulate the grating to the zero order. Adjust the spectrometer to the imaging mode, select an appropriate exposure time, and finely adjust the distance between the sample and the dark-field collection module until the image is clear. At the same time, adjust the sample position so that the area to be measured of the sample is aligned with the center of the pinhole aperture. Finally, adjust the aperture size of the pinhole aperture to adjust the imaging area to match the area of the sample to be measured. Then, adjust the spectrometer slit and collect the sample topography image through the spectrometer.

[0017] Step 2: Control the moving mechanism to move the second lens out of the optical path of the dark-field collection module. Adjust the spectrometer to the spectral measurement mode, and at the same time, adjust the central wavelength of the spectrometer grating to the wavelength band to be measured. Collect the sample dispersion spectrum through the spectrometer.

[0018] The described micro-region optical dispersion measurement method based on dark-field scattering further includes a step of calibrating the pixel resolution of the spectrometer. The specific method is as follows:

[0019] Set a transmission grating with a known grating constant d on the sample stage, make the laser incident on the transmission grating, control the moving mechanism to move the second lens out of the optical path of the dark-field collection module, adjust the spectrometer to the spectral measurement mode, measure the transmission spectrum of the transmission grating, and determine the number of pixels △Y corresponding to the distance between the zero-order fringe and the first-order fringe after passing through the transmission grating. Calculate the pixel resolution M of the spectrometer. The calculation formula is:

[0020]

[0021] dsinθ = mλ;

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

[0023] The described micro-region optical dispersion measurement method based on dark-field scattering further includes a step of adjusting the sample direction so that the KY direction is the same as the spectrometer slit direction, and a step of 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 energy band clarity.

[0024] The present invention has the following beneficial effects compared with the prior art:

[0025] 1. The present invention proposes a micro-region optical dispersion measurement system and method based on dark-field scattering, which utilizes 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 micro-nano structures. Compared with the reflection signal, the dark-field scattering signal effectively eliminates the interference of the incident light mode, thus more accurately and directly characterizing the intrinsic state of the sample. The present invention can provide more intrinsic data without introducing additional interference and can accurately measure the dispersion relationship of micro-region materials.

[0026] 2. The broadband illumination light source of the present invention adopts an oblique incidence excitation method. According to the law of reflection of light, the reflected light cannot enter the collection optical path. Only the scattered light on the surface of the sample enters the collection optical path, avoiding the interference of the excitation light mode, which is more conducive to characterizing the intrinsic state of the sample. At the same time, the dark field mode is more conducive to observing the morphology of tiny particles on the surface of the sample, significantly improving the imaging resolution of the sample. Therefore, the present invention has the advantages of high integration of the optical path structure, high measurement accuracy, and simplified measurement process.

[0027] 3. The broadband illumination light sources adopted by the present invention, such as halogen lamps, xenon lamps, and supercontinuum white light sources, enable the system to obtain the optical properties of the sample at multiple wavelengths at one time, reducing the need for multiple measurements and improving the experimental efficiency. The present invention greatly improves the accuracy and efficiency of optical dispersion measurement, and has important scientific research value and practical application prospects in many fields such as materials science and semiconductor manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the optical path of a micro-region optical dispersion measurement system based on dark field scattering provided by Embodiment 1 of the present invention;

[0029] Figure 2 It is a schematic diagram of the optical path in the imaging mode in Embodiment 2 of the present invention;

[0030] Figure 3 It is a schematic diagram of the optical path in the spectrum measurement mode in Embodiment 2 of the present invention;

[0031] Figure 4 It is a schematic diagram of the sample structure in Embodiment 2 of the present invention;

[0032] Figure 5 It is a dispersion relation diagram of the grating along the KY direction collected in Embodiment 2 of the present invention;

[0033] In the figure: 1 - broadband 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 OF THE EMBODIMENTS

[0034] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0035] Example 1

[0036] As Figure 1 shown, Example 1 of the present invention provides a micro-region optical dispersion measurement system based on dark-field scattering, including: a sample stage 5, an oblique-incidence excitation module, and a dark-field collection module; the sample stage 5 is used to place a sample 6.

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

[0038] Specifically, in this embodiment, the dark-field collection module includes a collection objective lens 7, a first lens 8, a small-aperture diaphragm 9, a second lens 11, a moving mechanism, a third lens 12, and a spectrometer 13 that are sequentially arranged above the sample from bottom to top and whose optical axis directions are perpendicular to the sample; the sample is located at the front focal plane of the collection objective lens 7, the distance between the rear focal plane of the collection objective lens 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 small-aperture diaphragm 9 is equal to the focal length of the first lens 8; the distance between the small-aperture 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 optical path of the dark-field collection module through a moving mechanism 14, and the moving mechanism 14 is used to drive the second lens 11 to place it in or out of the optical path of the dark-field collection module.

[0039] Specifically, in this embodiment, the broadband illumination light source 1 is a halogen lamp, a xenon lamp, or a supercontinuum white light source, and the spectrometer 13 is a matrix spectrometer.

[0040] Furthermore, in this embodiment, the dark-field collection optical path further includes a polarization analyzer 10, and the polarization analyzer 10 is used to adjust the polarization of the collected scattered light. The sample stage is a three-dimensional adjustment mechanism, and through the three-dimensional adjustment mechanism, the three-dimensional position of the sample can be adjusted to achieve confocal between the sample and the collection objective lens 7 and the adjustment of the sample measurement area.

[0041] Furthermore, in this embodiment, the polarization analyzer 10 includes a polarizer and a quarter-wave plate, and the Stokes parameters are obtained by adjusting the optical axis angles of the polarizer and the quarter-wave plate, and then the polarization state of the scattered light signal can be obtained.

[0042] Further, in this embodiment, the lens group includes a fourth lens 2, a fifth lens 3, and an illumination objective lens 4. The broadband light output by the broadband illumination light source 1 is obliquely incident on the sample stage 5 after passing through the fourth lens 2, the fifth lens 3, and the illumination objective lens 4 in sequence. The distance between the broadband 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 rear focal plane of the illumination objective lens 4 is equal to the distance of the fifth lens 3. In addition, in this embodiment, the sample is located on the front focal plane of the illumination objective lens 4, and more illumination light utilization rate can be obtained.

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

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

[0045] The working principle of the embodiment of the present invention 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 lens 7 is converted into parallel light after passing through the collection objective lens 7, and then is focused on the plane of the small aperture stop 9 through the first lens 8, and then passes through the second lens 11 and the third lens 12 and is focused on the slit of the spectrometer 13 again; the grating of the spectrometer 13 is cut to the zero order, the software interface of the spectrometer is set to the imaging mode, and by setting the positions of the second lens 11 and the third lens 12, the center of the small aperture stop 9 can be imaged at the center of the spectrometer CCD. At the same time, moving the sample can make the area of the sample to be measured image at the center position of the small aperture stop, 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 all directions on the sample surface is presented at different points on the rear focal plane through the collection objective lens 7. The signals at different points on the rear focal plane of the collection objective lens 7 are refocused on the spectrometer slit by the first lens 8 and the third lens 12 again; the spectrometer is set to the spectral measurement mode. At this time, the signal perpendicular to the spectrometer slit is expanded along the wavelength, and the direction parallel to the spectrometer slit still carries the angle information of the rear focal plane, and the dispersion spectrum of the sample scattered signal is obtained.

[0048] In this embodiment, the selection of the sample area is jointly determined by the small aperture stop 9 with adjustable aperture and the slit of the spectrometer 13. The reason is that both the small aperture stop 9 and the slit of the spectrometer 13 are located at the confocal plane of the sample. For micro-nano structures, the small aperture stop 9 acts as a field stop, and can select the sample micro-region in the CCD when the collection optical path is in the imaging function, reducing the influence of the signals outside the micro-region to be measured.

[0049] Embodiment 2

[0050] Embodiment 2 of the present invention provides a micro-region optical dispersion measurement method based on dark-field scattering, which is implemented based on the micro-region optical dispersion measurement system 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 spectrometer 13 to fully open the slit and modulate the grating to the zero order. Adjust the spectrometer 13 to the imaging mode, select an appropriate exposure time, and finely adjust the distance between the sample and the dark-field collection module until the image is clear. At the same time, adjust the sample position so that the area to be measured of the sample is aligned with the center of the small aperture diaphragm 9. Finally, adjust the aperture size of the small aperture diaphragm 9 to adjust the imaging area, and after matching it with the area of the sample to be measured, adjust the slit of the spectrometer 13, and collect the sample topography image through the spectrometer 13.

[0052] As Figure 2 shown, when the second lens 11 is placed in the optical path of the dark-field collection module, the system is in the imaging mode. The surface information of the sample is first reproduced at the small aperture diaphragm 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. On the premise of determining the center position of the spectrometer array, by finely adjusting the two-dimensional mirror frame mounting the second lens 11, the image of the small aperture diaphragm 9 is adjusted to the center of the spectrometer array. Then select an appropriate exposure time for the CCD, and at the same time finely adjust the position of the sample stage along the optical axis back and forth to obtain a clear image of the sample, and adjust the area to be measured of the sample through the sample stage so that it is imaged at the center of the small aperture diaphragm 9. Finally, adjust the aperture size of the small aperture diaphragm 9 to make it as close as possible to the size of the sample area to be measured, and reduce the slit of the spectrometer to improve the measurement accuracy while reducing the influence of stray light.

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

[0054] As Figure 3 shown, when the second lens 11 moves out of the optical path of the dark-field collection module, the system is in the momentum space acquisition mode. The momentum space information at the rear focal plane of the collection objective lens 7 is transformed into parallel light by the first lens 8, and then focused on the slit of the spectrometer 13 by the third lens 12. Modulate the central wavelength of the spectrometer 13 grating to the wavelength band to be measured, and the grating will expand the wavelength of the light perpendicular to the spectrometer slit direction due to dispersion. 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 rear focal plane of the collection objective lens 7 are in a conjugate state, and both contain the angular information of the sample scattered light, and the momentum space angular information along the slit direction is retained. Thus, the wavelength-angle information of the scattered light of the micro-region sample, that is, the dispersion spectrum, can be obtained through the spectrometer.

[0055] In this embodiment, the angular resolution of the spectrometer is jointly determined by the NA value of the second objective lens (7) and the magnification factors of the third lens (8) and the fifth lens (12); before the formal measurement, it is necessary to first calibrate the pixel resolution of the spectrometer. Further, a micro-area optical dispersion measurement method based on dark-field scattering in this embodiment further includes a step of calibrating the pixel resolution of the spectrometer, and the specific method is as follows:

[0056] Set a transmission grating with a known grating constant d on the sample stage, make the laser incident on the transmission grating, control the moving mechanism to move the second lens 11 out of the optical path of the dark-field collection module, adjust the spectrometer 13 to the spectral measurement mode, measure the transmission spectrum of the transmission grating, and determine the number of pixels △Y corresponding to the distance between the zero-order fringe and the first-order fringe after passing through the transmission grating; calculate the pixel resolution M of the spectrometer, and the calculation formula is:

[0057]

[0058] dsinθ=mλ; (2)

[0059] where 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, a micro-area optical dispersion measurement method based on dark-field scattering in this embodiment further includes a step of adjusting the sample direction so that the KY direction is the same as the spectrometer slit direction.

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

[0062] Specifically, in this embodiment, a PMMA grating fabricated by the EBL process on a 1 cm × 1 cm ITO glass is placed on the sample stage, with a period of 400 nm, a grating line width of 240 nm, a grating area size of 40 μm × 40 μm, and the TiO2 layer and PMMA thickness are both 60 nm. The schematic diagram of the sample structure is as Figure 4As shown in the figure. The specific manufacturing process is as follows: First, a 60-nm-thick TiO2 layer is deposited on the ITO glass by a coating machine. Secondly, 60 nm of PMMA is spin-coated by controlling the spin-coating speed and time. Then, the area outside the grating lines is exposed using an electron beam, and the solubility of the PMMA in the area bombarded by the electron beam will change. Finally, after development and fixing, the grating structure is obtained. Among them, TiO2 plays a waveguide role, and the one-dimensional grating structure of PMMA is used to regulate the light field in the Brillouin zone. Here, by adjusting the sample direction, the KY direction of the sample is aligned with the spectrometer slit, and the angle of the polarizer in the polarization analyzer 10 is adjusted to make the measured energy band the clearest, which can filter out the interference of the impurity bands near the required energy band while improving the resolution.

[0063] As Figure 5 shown, it is the dispersion relation diagram of the grating along the KY direction measured by the present invention.

[0064] In summary, the present invention proposes 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, bandgap properties, dispersion relation, etc. of micro-nano structures. Compared with the reflection signal, the dark-field scattering signal effectively eliminates the interference of the incident light mode, thus more accurately and directly characterizing the intrinsic state of the sample. The present invention can provide more intrinsic data without introducing additional interference and can accurately measure the dispersion relation of micro-area materials.

[0065] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some 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 present invention.

Claims

1. A micro-region optical dispersion measurement system based on dark-field scattering, characterized in that, Comprising: A sample stage, an oblique-incidence excitation module, and a dark-field collection module; The sample stage is used for placing a sample; The oblique-incidence excitation module includes a broadband illumination light source (1) and a lens group; the broadband light output by the broadband illumination light source (1) forms parallel light after passing through the lens group and obliquely irradiates the sample; The dark-field collection module includes a collection objective lens (7), a first lens (8), a small-aperture diaphragm (9), a second lens (11), a moving mechanism, a third lens (12), and a spectrometer (13) that are sequentially arranged above the sample from bottom to top and whose optical axis directions are perpendicular to the sample; the sample is located at the front focal plane of the collection objective lens (7), the distance between the rear focal plane of the collection objective lens (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 small-aperture diaphragm (9) is equal to the focal length of the first lens (8); the distance between the small-aperture 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 optical path of the dark-field collection module through the moving mechanism (14), and the moving mechanism is used to drive the second lens (11) to be placed in or removed from the optical path of the dark-field collection module.

2. The micro-region optical dispersion measurement system based on dark-field scattering according to claim 1, wherein The broadband illumination light source (1) is a halogen lamp, a xenon lamp, or a supercontinuum white light source, and the spectrometer (13) is a planar array spectrometer.

3. The micro-region optical dispersion measurement system based on dark-field scattering according to claim 1, wherein The dark-field collection optical path further includes a polarization analyzer device (10), and the polarization analyzer device (10) is used to adjust the polarization of the collected scattered light, and the sample stage is a three-dimensional adjustment mechanism.

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

5. The micro-region optical dispersion measurement system based on dark-field scattering according to claim 1, wherein The lens group includes a fourth lens (2), a fifth lens (3), and an illumination objective lens (4), and the broadband light output by the broadband illumination light source (1) is obliquely irradiated on the sample stage (5) after passing through the fourth lens (2), the fifth lens (3), and the illumination objective lens (4) in sequence. The distance between the broadband 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 rear focal plane of the illumination objective lens (4) is equal to the distance of the fifth lens (3).

6. The micro-region optical dispersion measurement system based on dark-field scattering according to claim 1, characterized in that, The broadband light output by the broadband illumination light source (1) forms parallel light and obliquely irradiates the sample stage (5) at an incident angle of 30-60°.

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

8. A method for measuring micro-area optical dispersion based on dark-field scattering, which is implemented based on the micro-area optical dispersion measurement system based on dark-field scattering described in claim 1, and is characterized in that, Including 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 spectrometer (13) slit to be fully opened and the grating modulation to be at zero order, adjust the spectrometer (13) to the imaging mode, select an appropriate exposure time, finely adjust 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 area to be measured of the sample is aligned with the center of the small-aperture diaphragm (9); Finally, adjust the aperture size of the small-aperture diaphragm (9) to adjust the imaging area, make it match the area of the sample to be measured, adjust the spectrometer (13) slit, and collect the sample morphology image through the spectrometer (13). Step 2: Control the moving mechanism to move the second lens (11) out of 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 central wavelength of the grating of the spectrometer (13) to the wavelength band to be measured, and collect the dispersion spectrum of the sample through the spectrometer (13).

9. The method for measuring micro-area optical dispersion based on dark-field scattering according to claim 8, wherein It also includes the step of calibrating the pixel resolution of the spectrometer, and the specific method is as follows: Set a transmission grating with a known grating constant d on the sample stage, make the laser incident on the transmission grating, control the moving mechanism to move the second lens (11) out of the optical path of the dark field collection module, adjust the spectrometer (13) to the spectral measurement mode, measure the transmission spectrum of the transmission grating, and determine the number of pixels △Y corresponding to the distance between the zero-order fringe and the first-order fringe after passing through the transmission grating; calculate the pixel resolution M of the spectrometer, and the calculation formula is: dsinθ = mλ; where d represents the grating constant, θ represents the diffraction angle, λ represents the wavelength, m represents the grating order, and m = 1.

10. A method for measuring micro-region optical dispersion based on dark-field scattering according to claim 8, characterized in that, It also includes the step of adjusting the sample direction so that the KY direction is the same as the spectrometer slit direction, and the step of 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 energy band clarity.

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