Edge Detection Imaging Method Based on First-Order One-Dimensional Differential Operation Function Metasurface

Abstract

Edge detection imaging method based on a metasurface with a first-order one-dimensional differential operation function, which relates to an edge detection imaging method. The present invention aims to solve the problems of poor imaging quality of spatial light modulators, difficulty in integration, and high cost. The steps of the present invention include: Step 1, designing and fabricating a metasurface with the characteristics of a first-order one-dimensional differential operation function through simulation means; Step 2, building an optical system with the metasurface as the core for first-order one-dimensional differential operation function modulation, imaging the input image to be measured through the metasurface to obtain an edge detection image; Step 3, determining the edge contour of the input image through the development in the edge detection image to achieve the edge detection effect. The present invention belongs to the technical field of optical microscopy imaging and optical manipulation.

Description

Technical Field

[0001] The present invention relates to an edge detection imaging method, belonging to the technical field of optical microscopy imaging and optical manipulation. Background Art

[0002] The first-order one-dimensional differential operation function describes the gradient of the input image data. Since an image can be represented as a set of points with different intensities, edge detection is to extract the edge information of the image. By using the first-order one-dimensional differential operation function, the gradient information of each part of the image is obtained. Among them, the part with a large gradient change is the edge of the image. Currently, the existing edge detection functions are mainly designed for the amplitude transmittance and phase transmittance of the pupil function. By introducing corresponding amplitude and phase modulation at the pupil plane of the system, the adjustment of the differential function of the system can be realized. The regulation of the light field is usually achieved by traditional light field regulation elements, including amplitude / phase masks, spatial light modulators, deformable mirrors, digital micromirror devices, etc. Among them, the most commonly used is the spatial light modulator. The quantization level distribution of its phase structure and the structural characteristics of the regulation unit determine the existence of the zero-order diffraction spot. The zero-order diffraction spot often occupies a large part of the energy and often overlaps with the modulated effective image, making the displayed image dim and blurred, seriously reducing the imaging quality. At the same time, the spatial light modulator usually can only regulate the amplitude or phase alone and cannot regulate them simultaneously. In addition, the spatial light modulator is relatively large in volume, making it impossible to integrate the edge detection imaging optical system.

[0003] To solve the problems of poor imaging quality, unfavorable integration, and high cost of the spatial light modulator, the idea of metasurface is introduced. A metasurface is an artificial element composed of nanostructures that can arbitrarily regulate the phase, intensity, and polarization response of the incident field with sub-wavelength resolution. Using the metasurface structure to replace the traditional optical element for imaging improves the problem of the traditional three-dimensional imaging optical system based on the spatial light modulator having zero-order and high-order diffraction and being difficult to integrate, greatly reducing the volume of the element and improving the imaging quality. In addition, the metasurface compatible with semiconductor processing technology has a much lower cost than the spatial light modulator composed of a controller, a liquid crystal panel, a communication module, etc. during large-scale production, resulting in a significant reduction in the cost of the entire system and increasing its practicality. Summary of the Invention

[0004] In order to solve the problems of poor imaging quality, unfavorable integration, and high cost of the spatial light modulator, the present invention further provides an edge detection imaging method based on a metasurface of a first-order one-dimensional differential operation function.

[0005] The technical solution adopted by the present invention to solve the above problems is as follows: The steps of the present invention include:

[0006] Step 1: Design and fabricate a metasurface with the characteristics of a first-order one-dimensional differential operation function through simulation means;

[0007] Step 2: Build an optical system with the metasurface as the core for modulating the first-order one-dimensional differential operation function. Image the input image to be measured through the metasurface to obtain an edge detection image;

[0008] Step 3: Determine the edge contour of the input image through the development in the edge detection image to achieve the edge detection effect.

[0009] Furthermore, the optical system includes an optical path composed of an illumination module and an imaging module;

[0010] The illumination module includes a transmissive illumination module and a reflective illumination module;

[0011] The imaging module includes a transmissive imaging module and a reflective imaging module.

[0012] Furthermore, the transmissive illumination module includes a fiber-coupled laser and a collimating lens arranged along the beam propagation direction;

[0013] The transmissive imaging module includes a microscope objective, a metasurface, and a CMOS camera;

[0014] The fiber-coupled laser, collimating lens, microscope objective, metasurface, and CMOS camera arranged along the beam propagation direction are located in the same vertical direction, and the central axes of the microscope objective and the metasurface coincide in the vertical direction.

[0015] Furthermore, the reflective illumination module includes a fiber-coupled laser, a collimating lens, and a semi-reflective semi-transmissive lens arranged along the beam propagation direction;

[0016] The reflective imaging module includes a microscope objective, a metasurface, and a CMOS camera;

[0017] The fiber-coupled laser and collimating lens arranged along the beam propagation direction are located in the same horizontal direction. The semi-reflective semi-transmissive lens, microscope objective, metasurface, and CMOS camera are located in the same vertical direction, and the central axes of the microscope objective and the metasurface coincide in the vertical direction.

[0018] Furthermore, the object plane, metasurface, and image plane form a 2f system, and the metasurface is placed on the Fourier plane of the 2f system.

[0019] Furthermore, the wavelength of the fiber-coupled laser arranged along the beam propagation direction is in the visible light band. The wavelength of the visible light band is 400nm - 650nm, and the light emitted from the fiber passes through the collimating lens to generate a parallel beam.

[0020] Furthermore, the incident parallel light passes through the geometric metasurface and adapts to the transmission phase metasurface, and the output is the modulated outgoing light beam.

[0021] Furthermore, in step 2, the transmission edge detection imaging method is used to obtain the edge detection image, and the specific steps include:

[0022] Step a: The fiber-coupled laser arranged along the light beam propagation direction emits laser with strong monochromaticity and coherence. After passing through the collimating lens, it forms parallel light, and the collimated light exits through the sample of the image to be measured.

[0023] Step b: The sample is imaged through the microscope objective lens and the metasurface. The rear focal plane of the objective lens coincides with the metasurface, forming a 2f system. The light passes through the metasurface for amplitude and phase regulation based on the transmission phase. The image after amplitude and phase modulation is collected by the CMOS camera.

[0024] Step c: The collected first-order one-dimensional differential operation function modulated image is solved, and the contour information of the image to be measured is determined through the light field intensity shown in the image, completing the edge detection.

[0025] Furthermore, in step 2, the reflection edge detection imaging method is used to obtain the edge detection image, and the specific steps include:

[0026] Step A: The fiber-coupled laser arranged along the light beam propagation direction emits laser with strong monochromaticity and coherence. After passing through the collimating lens, it forms parallel light.

[0027] Step B: The parallel light is absorbed by the objective lens through the semi-reflective semi-transmissive lens. The microscope objective lens has a numerical aperture matching the detail size to be resolved of the image to be measured, and can evenly project the light beam processed by the semi-reflective semi-transmissive lens onto the image to be measured. The light reflected by the sample of the image to be measured passes through the semi-reflective semi-transmissive lens and then through the metasurface for amplitude and phase regulation, realizing the first-order one-dimensional differential operation function modulation. The modulated image is collected by the CMOS camera.

[0028] Step C: The collected first-order one-dimensional differential operation function modulated image is solved, and the contour information of the image to be measured is determined through the light field intensity shown in the image, completing the edge detection.

[0029] The beneficial effects of the present invention are as follows: The present invention has the advantages of being easy to integrate, having no zero-order diffraction spot, and high imaging efficiency. The metasurface that generates the first-order one-dimensional differential operation function phase modulation is placed on the Fourier plane of the 2f system, replacing the traditional spatial light modulator. The image information of the sample is mapped to the Fourier plane, and the edge contour information of the sample is extracted in the form of the first-order one-dimensional differential operation on the Fourier plane. By solving the collected image contour information, the edge information of the sample to be measured on the imaging plane is obtained. Description of the Drawings

[0030] Figure 1 is a flowchart of the edge detection imaging method based on the metasurface with a first-order one-dimensional differential operation function according to the present invention;

[0031] Figure 2 is a schematic structural diagram of the transmission optical path of the edge detection imaging method based on the metasurface with a first-order one-dimensional differential operation function according to the present invention;

[0032] Figure 3 is a schematic structural diagram of the reflection optical path of the edge detection imaging method based on the metasurface with a first-order one-dimensional differential operation function according to the present invention;

[0033] Figure 4 is a schematic diagram of the unit structure of the metasurface according to the present invention;

[0034] Figure 5 is a schematic diagram of the phase distribution and amplitude distribution of the metasurface according to the present invention

[0035] Figure 6 is a schematic diagram of the micro-nano processing process flow of the metasurface according to the present invention;

[0036] Figure 7 is a schematic diagram of the electron microscope imaging result of a part of the metasurface according to the present invention;

[0037] Figure 2 In, 1 - fiber-coupled laser, 2 - collimating lens, 3 - image to be measured, 4 - objective lens, 5 - metasurface, 6 - CMOS camera;

[0038] Figure 3 In, 1 - fiber-coupled laser, 2 - collimating lens, 3 - semi-reflective semi-transmissive lens, 4 - microscope objective lens, 5 - image to be measured, 6 - metasurface, 7 - CMOS camera. Detailed Embodiments

[0039] Detailed Embodiment 1: In combination with Figure 1 This embodiment is described. The steps of the edge detection imaging method based on the metasurface with a first-order one-dimensional differential operation function according to this embodiment include:

[0040] Step 1: Design and fabricate a metasurface with the characteristics of a first-order one-dimensional differential operation function through simulation means;

[0041] Step 2: Build an optical system that uses the metasurface as the core to modulate the first-order one-dimensional differential operation function, image the input image to be measured through the metasurface, and obtain an edge detection image;

[0042] Step 3: Determine the edge contour of the input image through the development in the edge detection image to achieve the edge detection effect.

[0043] In this embodiment, the basic unit structure of the metasurface is a single-crystalline silicon multi-degree-of-freedom nanorod on a sapphire substrate, where the period of the nanorods P = 500 nm, and the height H = 360 nm. By using the frequency-domain calculation module of the electromagnetic simulation software CST to perform parameter scanning on the length and width of the nanorods, the corresponding S-parameter curves are obtained to analyze the transmittance of circularly polarized light. Finally, a structure with a higher transmittance of circularly polarized light under specific wavelength conditions is found, and the length of the nanorods is selected L = 450 nm, and the width W = 450 nm. According to the phase distribution of the first-order one-dimensional differential operation function, by arranging the transmission phases, the basic unit structures are periodically arranged to form a complete metasurface.

[0044] In this embodiment, the metasurface generates the phase modulation of the first-order one-dimensional differential operation function. Specifically, the expression of the first-order one-dimensional differential operation function is:

[0045]

[0046] is the Fourier transform operation, is the complex amplitude distribution of the metasurface, is the complex amplitude distribution of the light field on the image plane, is the complex amplitude distribution of the light field on the object plane, is the imaginary unit, is the horizontal coordinate of the light field axis centered on the optical axis. From the complex amplitude distribution of the metasurface, the phase and intensity of the first-order one-dimensional differential operation function can be obtained.

[0047] In this embodiment, the metasurface is fabricated by electron beam lithography (EBL) combined with reactive ion etching (RIE). A single-crystalline silicon epitaxial wafer with a thickness of 360 nm grown on a double-sided polished sapphire is selected as the processing material. Then, the electron beam resist PMMA A4 is spin-coated on the substrate at a speed of 3000 revolutions per minute (RPM). Using electron beam lithography technology, at an acceleration voltage of 30 kV, a beam current of 360 pA, and an area of 100 × 100 μm 2Under the writing-in conditions, the corresponding metasurface mask was fabricated on the photoresist. Subsequently, the sample was immersed in a 25% tetramethylammonium hydroxide (TMAH) solution at room temperature (25 °C) for 2 min, rinsed with deionized water for 20 s, immersed in an isopropyl alcohol (IPA) solution for 10 s, and then dried with nitrogen. Subsequently, inductively coupled plasma reactive ion etching was used to transfer the pattern onto the silicon film. First, carbon tetrafluoride (CF4) was used at an ICP power of 100 W and a bias power of 100 W, with a gas flow rate of 45 sccm for 5 s to remove the surface oxide layer by dry etching. Then, hydrogen bromide gas (HBr) was used with a gas flow rate of 100 sccm, an ICP power of 400 W, and a bias power of 100 W to etch the silicon at a rate of 83 nm / min. During the etching process, the substrate stage temperature was set to 20 °C, and the chamber pressure was set to 10 mTorr. Finally, the sample was immersed in 10% hydrofluoric acid (HF) for 15 s to remove the remaining photoresist mask, washed with deionized water, and finally dried with nitrogen to obtain the processed metasurface.

[0048] The present invention is based on the traditional first-order one-dimensional differential operation function imaging method. By using the metasurface to generate the modulation of the first-order one-dimensional differential operation function, it not only avoids the influence of the zero-order diffraction spot, improves the energy utilization rate and imaging efficiency, but also improves the integration and lightweight of the system. Combining the characteristics of the first-order one-dimensional differential operation function with the advantages of the metasurface can perform high-precision edge detection while reducing the complexity of the system, making the system easier to integrate and meeting the usage requirements of the current edge detection system.

[0049] Step 1 specifically includes:

[0050] S101. Optimize the materials, shapes, geometric parameters, etc. of the metasurface, and use the frequency-domain calculation module based on the finite element method in the electromagnetic simulation software CST for simulation operations. When the unit structure period and the height of the nanorods are fixed, by changing the length and width of the nanorods, find the length and width with the maximum circular polarization transmittance within the dimension range suitable for processing as the unit structure for the transmission phase.

[0051] S102. Obtain the phase distribution of the first-order one-dimensional differential operation function from the complex amplitude expression of the first-order one-dimensional differential operation.

[0052] S103. Generate the processing file for the edge detection metasurface according to the selected unit structure and the phase distribution of the transmission phase.

[0053] S104. Use electron beam lithography combined with reactive ion beam etching to process the metasurface.

[0054] The unit structure of the metasurface designed according to step S101 is as Figure 4(a). Sapphire crystal (Al2O3) with good transmittance in the visible light band is used as the substrate, on which there are nanocolumns composed of high refractive index material Si, and the structure is as shown in Figure 4 (b). The period P = 400 nm is selected, the height H of the nanorods is 360 nm, the length and width of the nanorods are scanned for parameters, and the corresponding S-parameter curves are obtained to analyze the cross-polarization transmittance of circularly polarized light. Finally, a structure with a higher cross-polarization transmittance under the incident wave condition of 632 nm is found. At this time, the length L of the nanorods is 350 nm and the width W is 350 nm.

[0055] As shown in Figure 2 Step 2 specifically includes:

[0056] S201. The fiber-coupled laser 1 arranged along the light beam propagation direction emits laser light with strong monochromaticity and coherence. After passing through the collimating lens 2, it forms parallel light, and the collimated light exits through the image to be measured 3.

[0057] S202. The microscopic objective lens 4 collects the light transmitted through the image sample to be measured. The metasurface 5 is placed on the rear focal plane of the objective lens 4, and the two form a 2f system. The light received by the objective lens 4 passes through the metasurface 5 for amplitude and phase modulation, and the image after amplitude and phase modulation is collected by the CMOS camera 6. The image of the image sample to be measured is modulated by a first-order one-dimensional differential operation function, and the contour information of the image sample to be measured is obtained on the CMOS camera, and the edge data is acquired.

[0058] As shown in Figure 3 Step 2 specifically includes:

[0059] S201. The fiber-coupled laser 1 arranged along the light beam propagation direction emits laser light with strong monochromaticity and coherence. After passing through the collimating lens 2, it forms parallel light.

[0060] S202. The parallel light is absorbed by the objective lens 4 through the semi-reflective and semi-transmissive lens 3. The microscopic objective lens has a numerical aperture matching the detail size to be resolved of the image to be measured, and can uniformly project the light beam processed by the semi-reflective and semi-transmissive lens on the image to be measured 5. The light reflected by the image sample to be measured passes through the semi-reflective and semi-transmissive lens 3 and then passes through the metasurface 6 for amplitude and phase regulation to achieve first-order one-dimensional differential operation function modulation. The rear focal plane of the microscopic objective lens coincides with the metasurface, and the two form a 2f system. The image after phase modulation is collected by the CMOS camera 7.

[0061] Specific Embodiment 2: Combining Figures 1 to 7 This embodiment is described. The optical system of the edge detection imaging method based on the metasurface of the first-order one-dimensional differential operation function includes an optical path composed of an illumination module and an imaging module;

[0062] The illumination module includes a transmissive illumination module and a reflective illumination module;

[0063] The imaging module includes a transmissive imaging module and a reflective imaging module.

[0064] Specific Embodiment Three: In combination with Figures 1 to 7 To illustrate this embodiment, the transmissive illumination module of the edge detection imaging method based on the first-order one-dimensional differential operation function metasurface described in this embodiment includes a fiber-coupled laser and a collimating lens arranged along the light beam propagation direction;

[0065] The transmissive imaging module includes a microscope objective lens, a metasurface, and a CMOS camera;

[0066] The fiber-coupled laser, the collimating lens, the microscope objective lens, the metasurface, and the CMOS camera arranged along the light beam propagation direction are located in the same vertical direction, and the central axes of the microscope objective lens and the metasurface coincide in the vertical direction.

[0067] Specific Embodiment Four: In combination with Figures 1 to 7 To illustrate this embodiment, the reflective illumination module of the edge detection imaging method based on the first-order one-dimensional differential operation function metasurface described in this embodiment includes a fiber-coupled laser, a collimating lens, and a semi-reflective semi-transmissive lens arranged along the light beam propagation direction;

[0068] The reflective imaging module includes a microscope objective lens, a metasurface, and a CMOS camera;

[0069] The fiber-coupled laser and the collimating lens arranged along the light beam propagation direction are located in the same horizontal direction. The semi-reflective semi-transmissive lens, the microscope objective lens, the metasurface, and the CMOS camera are located in the same vertical direction, and the central axes of the microscope objective lens and the metasurface coincide in the vertical direction.

[0070] Specific Embodiment Five: In combination with Figures 1 to 7 To illustrate this embodiment, the object plane, the metasurface, and the image plane of the edge detection imaging method based on the first-order one-dimensional differential operation function metasurface described in this embodiment form a 2f system, and the metasurface is placed on the Fourier plane of the 2f system.

[0071] Specific Embodiment Six: In combination with Figures 1 to 7 To illustrate this embodiment, the wavelength of the fiber-coupled laser arranged along the light beam propagation direction of the edge detection imaging method based on the first-order one-dimensional differential operation function metasurface described in this embodiment is in the visible light band, the wavelength of the visible light band is 400nm - 650nm, and the light emitted from the fiber is collimated by the collimating lens to generate a parallel light beam.

[0072] Specific Embodiment Seven: In combination with Figures 1 to 7To illustrate this embodiment, in the edge detection imaging method based on the first-order one-dimensional differential operation function metasurface described in this embodiment, the incident parallel light passes through the geometric metasurface, adapts to the transmission phase metasurface, and outputs a regulated outgoing light beam.

[0073] Specific implementation method eight: Combination Figures 1 to 7 This embodiment is described. In step 2 of the edge detection imaging method based on the first-order one-dimensional differential operation function metasurface described in this embodiment, a transmission edge detection imaging method is used to obtain an edge detection image. The specific steps include:

[0074] Step a, the fiber-coupled laser arranged along the propagation direction of the light beam emits a laser with strong monochromaticity and coherence, which is formed into parallel light through a collimating lens, and the collimated light is emitted through the image sample to be measured;

[0075] Step b, imaging the sample through a microscope objective and a metasurface, the back focal plane of the objective coincides with the metasurface to form a 2f system, the light passes through the metasurface and the amplitude and phase are modulated based on the transmission phase, and the image after amplitude and phase modulation is collected by a CMOS camera;

[0076] Step c: solving the acquired first-order one-dimensional differential operation function modulated image, determining the contour information of the image to be tested through the light field intensity displayed in the image, and completing edge detection.

[0077] Specific implementation method nine: Combination Figures 1 to 7 This embodiment is described. In step 2 of the edge detection imaging method based on the first-order one-dimensional differential operation function metasurface described in this embodiment, a reflective edge detection imaging method is used to obtain an edge detection image. The specific steps include:

[0078] Step A, the fiber-coupled laser arranged along the propagation direction of the light beam emits a laser with strong monochromaticity and coherence, which is formed into parallel light through a collimating lens;

[0079] Step B, parallel light is absorbed by an objective lens through a half-reflecting half-mirror lens, the microscope objective lens has a numerical aperture that matches the detail size to be resolved of the image to be measured, and can evenly project the light beam processed by the half-reflecting half-mirror lens onto the image to be measured; the light reflected by the sample of the image to be measured passes through the half-reflecting half-mirror lens and then passes through the metasurface, and amplitude and phase are controlled to achieve first-order one-dimensional differential operation function modulation, and the image formed after modulation is collected by a CMOS camera;

[0080] Step C: solve the collected first-order one-dimensional differential operation function modulated image, determine the contour information of the image to be tested through the light field intensity displayed in the image, and complete edge detection.

[0081] The above are only the preferred embodiments of the present invention, and do not impose any form of limitation on the present invention. Although the present invention has been disclosed above with the preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, may make some changes or modifications to the above-disclosed technical content to obtain equivalent embodiments with equivalent changes. However, as long as it does not depart from the content of the technical solution of the present invention, and according to the technical essence of the present invention, any simple modification, equivalent replacement, and improvement made to the above embodiments within the spirit and principles of the present invention still fall within the protection scope of the technical solution of the present invention.

Claims

1. Edge detection imaging method based on a first-order one-dimensional differential operation function metasurface, characterized in that: The steps of the edge detection imaging method based on the first-order one-dimensional differential operation function metasurface include: Step 1: Design and fabricate a metasurface with the characteristics of the first-order one-dimensional differential operation function by means of simulation; specifically including: S101: Optimize the material, shape, and geometric parameters of the metasurface, and perform simulation operations using the frequency-domain calculation module based on the finite element method in the electromagnetic simulation software CST. When the unit structure period and the height of the nanorods are certain, by changing the length and width of the nanorods, find the length and width with the maximum circular polarization transmittance within the dimension range suitable for processing as the unit structure of the transmission phase. S102: Obtain the phase distribution of the first-order one-dimensional differential operation function from the complex amplitude expression of the first-order one-dimensional differential operation. S103: Generate the processing file of the edge detection metasurface according to the selected unit structure and in combination with the phase distribution of the transmission phase. S104: Fabricate the metasurface by means of electron beam lithography combined with reactive ion beam etching. The metasurface is fabricated by electron beam lithography combined with reactive ion etching. A single-crystalline silicon epitaxial wafer with a thickness of 360 nm grown on a double-sided polished sapphire is selected as the processing material. Then, the electron beam resist PMMA A4 is spin-coated on the substrate at a speed of 3000 revolutions per minute. Using electron beam lithography technology, under the writing field conditions of an acceleration voltage of 30 kV, a beam current of 360 pA, and a writing field of 100 × 100 μm 2 , the corresponding superlens mask is prepared on the photoresist. Subsequently, the sample is immersed in a 25% tetramethylammonium hydroxide solution at room temperature for 2 min, rinsed with deionized water for 20 s, immersed in an isopropyl alcohol solution for 10 s, and then dried with nitrogen. Subsequently, the pattern is transferred to the silicon film by inductively coupled plasma reactive ion etching. First, carbon tetrafluoride is used to remove the surface oxide layer by dry etching at an ICP power of 100 W, a bias power of 100 W, and a gas flow rate of 45 sccm for 5 s. Then, hydrogen bromide gas is used with a gas flow rate of 100 sccm, an ICP power of 400 W, and a bias power of 100 W to etch silicon at a speed of 83 nm / min. During the etching process, the substrate stage temperature is set at 20°C, and the chamber pressure is set at 10 mTorr. Finally, the sample is immersed in 10% hydrofluoric acid for 15 s to remove the remaining photoresist mask, washed with deionized water, and finally dried with nitrogen to obtain the processed metasurface; Step 2: Build an optical system with the metasurface as the core for modulating the first-order one-dimensional differential operation function, image the input image to be measured through the metasurface, and obtain the edge detection image. Step 3: Determine the edge contour of the input image through the development in the edge detection image to achieve the edge detection effect.

2. The edge detection imaging method based on the metasurface of the first-order one-dimensional differential operation function according to claim 1, wherein: The optical system includes an optical path composed of an illumination module and an imaging module. The illumination module includes a transmissive illumination module and a reflective illumination module. The imaging module includes a transmissive imaging module and a reflective imaging module.

3. The edge detection imaging method based on the metasurface of the first-order one-dimensional differential operation function according to claim 2, wherein: The transmissive illumination module includes a fiber-coupled laser and a collimating lens arranged along the beam propagation direction. The transmissive imaging module includes a microscope objective, a metasurface, and a CMOS camera. The fiber-coupled laser, the collimating lens, the microscope objective, the metasurface, and the CMOS camera arranged along the beam propagation direction are located in the same vertical direction, and the central axes of the microscope objective and the metasurface coincide in the vertical direction.

4. The edge detection imaging method based on the metasurface of the first-order one-dimensional differential operation function according to claim 2, characterized in that: The reflective illumination module includes a fiber-coupled laser, a collimating lens, and a semi-reflective semi-transmissive lens arranged along the beam propagation direction. The reflective imaging module includes a microscope objective, a metasurface, and a CMOS camera. The fiber-coupled laser and the collimating lens arranged along the beam propagation direction are located in the same horizontal direction; the semi-reflective semi-transmissive lens, the microscope objective, the metasurface, and the CMOS camera are located in the same vertical direction, and the central axes of the microscope objective and the metasurface coincide in the vertical direction.

5. The edge detection imaging method based on the metasurface of the first-order one-dimensional differential operation function according to claim 3 or 4, characterized in that: The object plane, the metasurface, and the image plane form a 2f system, and the metasurface is placed on the Fourier plane of the 2f system.

6. The edge detection imaging method based on the metasurface of the first-order one-dimensional differential operation function according to claim 3 or 4, characterized in that: The wavelength of the fiber-coupled laser arranged along the beam propagation direction is in the visible light band, the wavelength of the visible light band is 400nm - 650nm, and the light emitted from the fiber passes through the collimating lens to generate a parallel beam.

7. The edge detection imaging method based on the metasurface of the first-order one-dimensional differential operation function according to claim 3 or 4, characterized in that: The incident parallel light passes through the geometric metasurface and the transmission phase metasurface, and outputs the modulated outgoing beam.

8. The edge detection imaging method based on the metasurface of the first-order one-dimensional differential operation function according to claim 1, characterized in that: In Step 2, the edge detection image is obtained by using the transmissive edge detection imaging method, and the specific steps include: Step a: The fiber-coupled laser arranged along the light beam propagation direction emits laser light with strong monochromaticity and coherence. After passing through the collimating lens, it forms parallel light, and the collimated light exits through the sample of the image to be measured. Step b: The sample is imaged through the microscope objective lens and the metasurface. The back focal plane of the objective lens coincides with the metasurface, forming a 2f system. The light passes through the metasurface for amplitude and phase regulation based on the transmission phase. The image after amplitude and phase modulation is collected by the CMOS camera. Step c: The acquired image modulated by the first-order one-dimensional differential operation function is solved, and the contour information of the image to be measured is determined through the light field intensity shown in the image, completing edge detection.

9. The edge detection imaging method based on the metasurface of the first-order one-dimensional differential operation function according to claim 1, characterized in that: In step 2, the edge detection image is obtained by using the reflective edge detection imaging method. The specific steps include: Step A: The fiber-coupled laser arranged along the light beam propagation direction emits laser light with strong monochromaticity and coherence. After passing through the collimating lens, it forms parallel light. Step B: The parallel light is absorbed by the objective lens through the semi-reflective semi-transmissive lens. The microscope objective lens has a numerical aperture matching the detail size to be resolved of the image to be measured, and can uniformly project the light beam processed by the semi-reflective semi-transmissive lens onto the image to be measured. The light reflected by the sample of the image to be measured passes through the semi-reflective semi-transmissive lens and then through the metasurface for amplitude and phase regulation, realizing modulation by the first-order one-dimensional differential operation function. The image formed after modulation is collected by the CMOS camera. Step C: The acquired image modulated by the first-order one-dimensional differential operation function is solved, and the contour information of the image to be measured is determined through the light field intensity shown in the image, completing edge detection.

Images