A wavelength-independent real-time polarization imaging method and device based on metasurface

Abstract

The present invention relates to a wavelength-independent, real-time polarization imaging method and device based on a metasurface, belonging to the field of polarization imaging. The method and device comprise a sample to be measured, a first lens, a two-dimensional polarization grating, a one-dimensional polarization grating, a second lens, a polarizer, and an image sensor, which are sequentially arranged along an optical path. After a light beam irradiates the sample to be measured, it passes through the first lens, and a portion of the light field enters the two-dimensional polarization grating for modulation, diffracting and splitting into two left-handed circularly polarized components and two right-handed circularly polarized components. A portion of the light field is directly transmitted to the one-dimensional polarization grating and diffracted and split into left-handed and right-handed circularly polarized components. After diffraction and splitting, at the focus of the second lens, one left-handed circularly polarized component and one right-handed circularly polarized component diffracted and split by the two-dimensional polarization grating completely overlap with the left-handed and right-handed circularly polarized components diffracted and split by the one-dimensional polarization grating, respectively. The light then passes through the polarizer and reaches the image plane of the image sensor. The present invention solves the wavelength dependence of existing single-exposure polarization imaging technologies.

Description

Technical Field

[0001] The present invention belongs to the field of polarization imaging, and in particular relates to a wavelength-independent real-time polarization imaging method and device based on a metasurface. Background Art

[0002] Polarization, a fundamental property of light waves that describes the direction of electric field vibration, plays a crucial role in light-matter interactions (e.g., reflection, transmission, and scattering). Polarization imaging can capture material information unattainable by traditional intensity imaging, such as surface morphology, structural orientation, and physical and chemical properties. It has been widely used in remote sensing, biodiagnosis, material characterization, and visual enhancement. Researchers have proposed various polarization detection techniques to achieve fast and accurate polarization acquisition and imaging.

[0003] A common strategy for polarization imaging is to observe the intensity of multiple polarization components sequentially in time and space, and calculate the polarization information in the form of Stokes parameters. This method requires mechanical rotation of polarization dichroic elements and optical elements, which makes it difficult to achieve system miniaturization and high temporal resolution, and mechanical rotation may introduce measurement errors. Metasurfaces can achieve Stokes vector detection in a single exposure by spatially dividing and focusing multiple polarization components simultaneously, utilizing the intensity distribution in different polarization channels. However, polarization imaging technology using a single metasurface requires orthogonal polarization separation with low crosstalk and high polarization extinction ratio, has strict wavelength dependence, and can only work at specific wavelengths. Summary of the Invention

[0004] Technical issues to be solved:

[0005] In order to avoid the shortcomings of the existing technology, the present invention provides a wavelength-independent real-time polarization imaging method and device based on a metasurface, aiming to solve the wavelength dependence existing in the existing single-exposure polarization imaging technology and reduce the complexity of metasurface design and preparation.

[0006] The technical solution of the present invention is: a wavelength-independent real-time polarization imaging device based on a metasurface, comprising a sample to be measured, a first lens, a two-dimensional polarization grating, a one-dimensional polarization grating, a second lens, a polarizer, and an image sensor arranged in sequence along an optical path, wherein the two-dimensional polarization grating and the one-dimensional polarization grating constitute a cascaded polarization grating;

[0007] After the light beam irradiates the sample to be tested, it passes through the first lens. Part of the light field enters the two-dimensional polarization grating for modulation and is diffracted and split into two left-handed circularly polarized components and two right-handed circularly polarized components. Part of the light field is directly transmitted to the one-dimensional polarization grating and is diffracted and split into left-handed and right-handed circularly polarized components. After diffraction and splitting, at the focus of the second lens, one left-handed circularly polarized component and one right-handed circularly polarized component split by the two-dimensional polarization grating completely overlap with the left-handed and right-handed circularly polarized components split by the one-dimensional polarization grating respectively. The light then passes through the polarizer to reach the image plane of the image sensor.

[0008] A further technical solution of the present invention is that the first lens and the second lens are two completely identical lenses and are placed according to a 4f optical imaging system.

[0009] A further technical solution of the present invention is that the two-dimensional polarization grating is located at the spectrum plane of the 4f optical imaging system. A further technical solution of the present invention is that the one-dimensional polarization grating is located at a distance Δz from the spectrum plane of the 4f optical imaging system, and the calculation formula of Δz is as follows:

[0010]

[0011] Where θ is the diffraction angle of the polarization grating, λ is the wavelength of the incident light, is the ideal maximum phase measurement resolution of the imaging device, and f is the focal length of the 4f optical imaging system.

[0012] A further technical solution of the present invention is that the two-dimensional polarization grating is a rectangular phase grating with a duty cycle of 0.5 and a phase difference of π along the x-direction, and is a blazed grating along the y-direction.

[0013] A further technical solution of the present invention is that the one-dimensional polarization grating is a blazed grating along both the x-direction and the y-direction.

[0014] A further technical solution of the present invention is that the two-dimensional polarization grating and the one-dimensional polarization grating are both designed as geometric phase metasurfaces.

[0015] A further technical solution of the present invention is: the image sensor is a CMOS.

[0016] A wavelength-independent real-time polarization imaging method based on a metasurface, the specific steps are as follows:

[0017] The incident light illuminates the sample to be tested and passes through the first lens, and the light field E in Entering the two-dimensional polarization grating for modulation, the diffraction is split into two left-handed circularly polarized components |L1>, |L2> and two right-handed circularly polarized components |R1>, |R2>. The distribution of the two-dimensional polarization grating diffraction field on the image plane is:

[0018] I R1=|| R1 >| 2 =|E Rin (x+Δ, y+Δ)|R>| 2

[0019] I R2 =||R2>| 2 =|E Rin (x-Δ, y+Δ)|R>| 2

[0020] I L1 =|| L1 >| 2 =|E Lin (x-Δ, y-Δ)L>| 2

[0021] I L2 =||L2>| 2 =|E Lin (x+Δ, y-Δ)|L>| 2

[0022] Wherein, Δ is the displacement of the left and right circular polarization components in the image plane of the 4f imaging system;

[0023] Light Field E in2 Directly transmitting onto a one-dimensional polarization grating located at a distance Δz from the spectrum plane, the outgoing light field is diffracted and split into left-handed and right-handed circularly polarized components |L3> and |R3>. The distribution of the one-dimensional polarization grating diffraction field on the image plane is:

[0024] I R3 =||R3>| 2 =|E Rin2 (x-Δ, y-Δ)exp[-i2πΔz tanθ(x+y) / λf]|R>| 2

[0025] I L3 =||L3>| 2 =|E Lin2 (x+Δ,y+Δ)exp[i2πΔz tanθ(x+y) / λf]|L>| 2 Where f is the focal length of the 4f optical imaging system, θ is the diffraction angle of the geometric phase metasurface, and i is an imaginary number;

[0026] At the image plane of the 4f optical imaging system, i.e., at the focus of the second lens, the diffraction components |L1> and |R1> of the two-dimensional polarization grating completely overlap with the diffraction components |R3> and |L3> of the one-dimensional polarization grating, respectively. The horizontal polarization interference intensity distributions of the left-handed and right-handed circularly polarized components obtained after horizontal polarization analysis by the polarizer are I1 and I2.

[0027] The phase difference between the left and right circular polarization components is obtained from the interference intensity distribution I1 or I2 by digital holography. The formula is as follows:

[0028]

[0029] in, is the phase difference between the left and right circular polarization components of the incident light field;

[0030] Calculate the Stokes parameter information of the light field to achieve full polarization imaging. The formula is as follows:

[0031]

[0032] Beneficial effects

[0033] The beneficial effects of the present invention are as follows: The proposed polarization imaging method constructs a control model of a cascade of two-dimensional and one-dimensional polarization gratings, achieving compact coaxial interferometric polarization imaging without requiring an additional reference beam. Leveraging the fundamental principle of geometric phase metasurfaces for applying conjugate phase modulation to both left-handed and right-handed circular polarization components, the design avoids crosstalk between polarization components and achieves orthogonal circular polarization separation with a high polarization extinction ratio.

[0034] The polarization imaging device proposed in the present invention can realize polarization imaging with only a single exposure. Figure 4 This device is used to measure the polarization state of the light field emitted by horizontally polarized light after it passes through a liquid crystal optical element. Thanks to the advantage of the geometric phase metasurface's ability to be controlled at multiple wavelengths, the measurement device can operate at multiple wavelengths. Figure 5 The experimental measurement results of the measurement device at different incident wavelengths verify that the device is applicable to polarization imaging at multiple wavelengths. The coaxial interferometer polarization imaging device proposed in this invention has a compact coaxial interferometer optical path structure. It no longer requires a high-coherence laser light source for input, and can also achieve polarization measurement of the light field using a low-coherence light source (LED light source) for illumination. Figure 6 These are the experimental measurement results of this device under the incidence of LED light source. The results show that this device can also realize polarization measurement of the light field under the incidence of low-coherence LED light source. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic diagram of the principle of the wavelength-independent real-time polarization imaging device based on metasurface proposed in the present invention.

[0036] Figure 2 Schematic diagram of the polarization splitting and interference principle of the wavelength-independent real-time polarization imaging self-interferometer based on metasurface proposed in the present invention;

[0037] FIG3( a ) is a schematic diagram of the phase structure of a one-dimensional polarization grating of a metasurface device used in an embodiment of the present invention;

[0038] FIG3( b ) is a schematic diagram of the phase structure of a two-dimensional polarization grating of a metasurface device used in an embodiment of the present invention;

[0039] FIG3(c) shows the two-dimensional polarization grating used in the embodiment of the present invention for left-handed circularly polarized light along the x-direction and the y-direction. and right circularly polarized light Phase modulation distribution;

[0040] FIG3( d ) is an optical microscope image (left) and a scanning electron microscope image (right) of a two-dimensional polarization grating used in an embodiment of the present invention;

[0041] FIG3( e ) is an optical microscope image (left) and a scanning electron microscope image (right) of a one-dimensional polarization grating used in an embodiment of the present invention;

[0042] Figure 4 Schematic diagram of experimental results in an embodiment of the present invention;

[0043] Figure 4 (a) Optical microscope image of a first-order liquid crystal vortex wave plate and the Stokes parameter distribution of the outgoing light field after horizontally polarized light passes through the first-order liquid crystal vortex wave plate;

[0044] Figure 4 (b) Optical microscope image of the second-order liquid crystal vortex wave plate and the Stokes parameter distribution of the outgoing light field after horizontally polarized light passes through the second-order liquid crystal vortex wave plate;

[0045] Figure 4 (c) is an optical microscope image of the liquid crystal depolarizer and the Stokes parameter distribution of the outgoing light field after horizontally polarized light passes through the liquid crystal depolarizer;

[0046] Figure 5 Schematic diagram of experimental results of the interferometer in an embodiment of the present invention under laser illumination of different wavelengths;

[0047] Figure 5 (a) Stokes parameter measurement results of the exiting light field of horizontally polarized light of different wavelengths (633 nm, 552 nm, and 473 nm) after passing through the second-order liquid crystal vortex wave plate in the embodiment;

[0048] Figure 5 (b) shows the distribution of the S3 component of the Stokes parameter of the outgoing light field of horizontally polarized light of different wavelengths (633 nm, 552 nm, and 473 nm) after passing through the second-order liquid crystal vortex wave plate in the embodiment along the angular coordinate;

[0049] Figure 5(c) shows the distribution of the Stokes parameters of the exiting light field of horizontally polarized light of different wavelengths (633 nm, 552 nm, and 473 nm) passing through the second-order liquid crystal vortex wave plate on the Poincare sphere in the embodiment;

[0050] Figure 6 Schematic diagram of experimental results using low-coherence light source LED lighting in an embodiment of the present invention;

[0051] Figure 6 (a) is the spectral range of the LED light source used in the embodiment;

[0052] Figure 6 (b) is an experimental intensity image collected after horizontally polarized light passes through a second-order liquid crystal vortex wave plate under the illumination of the LED light source used in the embodiment;

[0053] Figure 6 (c) Figure 6 (b) Local magnified image of the location of the box;

[0054] Figure 6 (d) is the Stokes parameter measurement result after horizontally polarized light passes through the second-order liquid crystal vortex wave plate under the illumination of the LED light source used in the embodiment.

[0055] Reference numerals: 1. Sample to be measured, 2. First lens L1, 3. Two-dimensional polarization grating MS2, 4. One-dimensional polarization grating MS1, 5. Second lens L2, 6. Polarizer P, 7. Image sensor CMOS; DHI stands for digital holographic interferometry, used to solve the phase DETAILED DESCRIPTION

[0056] The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the present invention, but should not be construed as limiting the present invention.

[0057] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0058] Based on the wavelength dependence of existing single-exposure polarization imaging technology and to reduce the complexity of metasurface design and preparation, a wavelength-independent real-time polarization imaging device based on a metasurface is proposed, which includes a sample to be measured, a first lens, a two-dimensional polarization grating, a one-dimensional polarization grating, a second lens, a polarizer, and an image sensor, which are arranged in sequence along the optical path, wherein the two-dimensional polarization grating and the one-dimensional polarization grating constitute a cascaded polarization grating; after the light beam irradiates the sample to be measured, it passes through the first lens, and part of the light field enters the two-dimensional polarization grating for modulation and is diffracted and split into two left-handed circularly polarized components and two right-handed circularly polarized components; part of the light field is directly transmitted to the one-dimensional polarization grating and is diffracted and split into left-handed and right-handed circularly polarized components; after diffraction and splitting, at the focus of the second lens, one left-handed circularly polarized component and one right-handed circularly polarized component diffracted and split by the two-dimensional polarization grating completely overlap with the left-handed and right-handed circularly polarized components diffracted and split by the one-dimensional polarization grating, respectively; and then reaches the image plane of the image sensor through the polarizer.

[0059] Specifically, the first lens and the second lens are two identical lenses, and are placed according to a 4f optical imaging system.

[0060] Specifically, the two-dimensional polarization grating is located at the spectrum plane of the 4f optical imaging system.

[0061] Specifically, the one-dimensional polarization grating is located at a distance Δz from the spectrum plane of the optical imaging system at a distance of 4f. The calculation formula of Δz is as follows:

[0062]

[0063] Where θ is the diffraction angle of the polarization grating, λ is the wavelength of the incident light, is the ideal maximum phase measurement resolution of the imaging device, and f is the focal length of the 4f optical imaging system.

[0064] Specifically, the two-dimensional polarization grating is a rectangular phase grating with a duty cycle of 0.5 and a phase difference of π along the x direction, and a blazed grating along the y direction. The one-dimensional polarization grating is a blazed grating along both the x and y directions.

[0065] Specifically, the two-dimensional polarization grating and the one-dimensional polarization grating are both designed as geometric phase metasurfaces.

[0066] Specifically, the image sensor is a CMOS.

[0067] The present invention provides a wavelength-independent real-time polarization imaging method based on a metasurface, and the specific steps are as follows:

[0068] Step 1: The incident light illuminates the sample to be tested and passes through the first lens, the light field E inEntering the two-dimensional polarization grating for modulation, the diffraction is split into two left-handed circularly polarized components |L1>, |L2> and two right-handed circularly polarized components |R1>, |R2>. The distribution of the two-dimensional polarization grating diffraction field on the image plane is:

[0069] I R1 =||R1>| 2 =|E Rin (x+Δ, y+Δ)|R>| 2

[0070] I R2 =||R2>| 2 =|E Rin (x-Δ, y+Δ)|R>| 2

[0071] I L1 =||L1>| 2 =|E Lin (x-Δ, y-Δ)|L> 2

[0072] I L2 =|| L2 >| 2 =|E Lin (x+Δ, y-Δ)|L> 2

[0073] Wherein, Δ is the displacement of the left and right circular polarization components in the image plane of the 4f imaging system;

[0074] Step 2: Light Field E in2 Directly transmitting onto a one-dimensional polarization grating located at a distance Δz from the spectrum plane, the outgoing light field is diffracted and split into left-handed and right-handed circularly polarized components |L3> and |R3>. The distribution of the one-dimensional polarization grating diffraction field on the image plane is:

[0075] I R3 =||R3>| 2 =|E Rin2 (x-Δ, y-Δ)exp[-i2πΔz tanθ(x+y) / λf]|R>| 2

[0076] I L3 =||L3>| 2 =|E Lin2 (x+Δ,y+Δ)exp[i2πΔz tanθ(x+y) / λf]|L>| 2

[0077] Where f is the focal length of the 4f optical imaging system, θ is the diffraction angle of the geometric phase metasurface, and i is an imaginary number;

[0078] Step 3: At the image plane of the 4f optical imaging system, i.e., at the focus of the second lens, the diffraction components |L1> and |R1> of the two-dimensional polarization grating completely overlap with the diffraction components |R3> and |L3> of the one-dimensional polarization grating, respectively. The horizontal polarization interference intensity distributions I1 and I2 of the left-handed and right-handed circularly polarized components are obtained after horizontal polarization analysis by the polarizer.

[0079] Step 4: Obtain the phase difference between the left and right circular polarization components from the interference intensity pattern I1 or I2 by digital holography The formula is as follows:

[0080]

[0081] in, is the phase difference between the left and right circular polarization components of the incident light field;

[0082] Step 5: Calculate the Stokes parameter information of the light field to achieve full polarization imaging. The formula is as follows:

[0083]

[0084] The above technical solution is further described below with reference to the accompanying drawings:

[0085] Reference Figure 1 As shown, this embodiment uses a wavelength-independent, real-time polarization imaging device based on a metasurface to perform real-time polarization imaging measurements. The experimental measurement device consists of two lenses (L1 and L2), a pair of cascaded polarization gratings (two-dimensional polarization grating MS2 and one-dimensional polarization grating MS1) formed by a geometric phase metasurface, a polarizer P, and a CMOS image sensor. The two lenses form a 4f imaging system, with the two-dimensional polarization grating located at the spectrum plane of the 4f imaging system, the one-dimensional polarization grating located at a distance Δz behind the spectrum plane, and the polarizer located after the second lens.

[0086] Reference Figure 2 As shown, the two-dimensional polarization grating is placed at the spectrum plane of the 4f imaging system composed of two lenses, and the light field E in Entering the two-dimensional polarization grating for modulation, it generates two pairs of orthogonal circularly polarized light fields (|L1>, |R1> and |L2>, |R2>) separated by diagonal and anti-diagonal diffraction, as well as the unmodulated direct light field component E in2 The one-dimensional polarization grating is placed at a distance Δz behind the spectrum plane. The direct light field component E in2Direct illumination onto a one-dimensional polarization grating generates diagonally diffracted orthogonal circularly polarized light fields (|R3> and |L3>). The diffracted orthogonal circularly polarized light fields are collected by the second lens of the 4f imaging system and imaged at the back focal plane. The |R3> and |L1> components overlap, and the |R1> and |L3> components overlap. After horizontal polarization analysis by the polarizer, interference intensity patterns I1 and I2 are formed. The |L2> and |R2> components are directly imaged at the back focal plane, and their intensities are I R and I L The phase difference of the orthogonal circular polarization components can be solved from the interference intensity diagram I1 or I2 This can be used to solve the Stokes parameter distribution of the incident light field.

[0087] The phase distribution of the geometric phase metasurface designed in this embodiment is as follows Figures 3(a)-3(c) As shown. The geometric phase distribution of a one-dimensional polarization grating is shown in Figure 3(a), which is a linear tilted phase along the angular direction. Figure 3(b) shows the geometric phase distribution of a two-dimensional polarization grating, which is a rectangular phase distribution along the x direction and a linear tilted phase distribution along the y direction. Figure 3(c) shows the phase modulation of a two-dimensional polarization grating on left-handed and right-handed circularly polarized light along the x and y directions.

[0088] A pair of geometric phase metasurfaces prepared in this embodiment are as follows Figure 3(d) and 3(e) Shown are the optical microscope image and scanning electron microscope image of a two-dimensional polarization grating, and the optical microscope image and scanning electron microscope image of a one-dimensional polarization grating, respectively.

[0089] The experimental measurement results of full polarization imaging in this embodiment are as follows: Figure 4 (a)-4(c) show the experimental measurement results of horizontally polarized light passing through first-order and second-order liquid crystal vortex wave plates, as well as a liquid crystal depolarizer. From left to right are optical microscopy images and Stokes parameter measurement results.

[0090] Figure 5 This is the experimental result of multi-wavelength full polarization measurement by the real-time polarization imaging self-interferometer proposed in this invention. This example measures the Stokes parameter distribution of the outgoing light field after horizontally polarized light of different wavelengths (633nm, 552nm, 473nm) passes through the second-order liquid crystal vortex wave plate. Figure 5 As shown in (a). Thanks to the advantage that the geometric phase metasurface can be controlled at multiple wavelengths, the polarization measurement method proposed in this invention has no wavelength dependence and can perform polarization imaging at multiple wavelengths without redesign. Figure 5 The experimental results shown verify the feasibility of this method for multi-wavelength measurements.

[0091] Figure 5(b) shows the distribution of the S3 component of the outgoing light field along the angular coordinate under different wavelengths of incidence. Figure 5 (b) The distribution of the Stokes parameters of the outgoing light field on the Poincare sphere under different wavelengths of incidence.

[0092] Figure 6 This is the verification result of the real-time polarization imaging self-interferometer proposed in the present invention under the illumination of a low-coherence light source. Figure 6 (a) is the spectral range of the illumination light source, with a central wavelength of 626 nm and a bandwidth of 10 nm. Figure 6 (b) is the experimental intensity image collected under low coherence light source illumination. Figure 6 (c) Figure 6 (b) Interference intensity diagram at the boxed position. The wavelength-independent real-time polarization imaging method and device based on the metasurface proposed in this invention has a compact optical path structure, greatly reducing the requirement for high coherence of the incident light source. It can also achieve polarization measurement of the light field under low-coherence light source illumination.

[0093] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention.

Claims

1. A wavelength-independent real-time polarization imaging device based on a metasurface, characterized by: The method comprises a sample to be measured, a first lens, a two-dimensional polarization grating, a one-dimensional polarization grating, a second lens, a polarizer, and an image sensor, which are sequentially arranged along an optical path, wherein the two-dimensional polarization grating and the one-dimensional polarization grating constitute a cascaded polarization grating; After irradiating the sample to be measured, the light beam passes through the first lens. Part of the light field enters the two-dimensional polarization grating for modulation and diffraction splitting into two left-handed circularly polarized components and two right-handed circularly polarized components. Part of the light field is directly transmitted to the one-dimensional polarization grating and diffracted and split into left-handed and right-handed circularly polarized components. After diffraction splitting, at the focus of the second lens, one left-handed circularly polarized component and one right-handed circularly polarized component split by the two-dimensional polarization grating completely overlap with the left-handed and right-handed circularly polarized components split by the one-dimensional polarization grating respectively. The light field then passes through the polarizer to reach the image plane of the image sensor. The first lens and the second lens are two identical lenses. f Optical imaging system placement; The two-dimensional polarization grating is located at 4 f At the spectrum plane of the optical imaging system; The one-dimensional polarization grating is located at a distance of 4 f Spectral surface of optical imaging system Department, The calculation formula is as follows: in, is the diffraction angle of the polarization grating, λ is the wavelength of incident light, is the ideal maximum phase measurement resolution of the imaging device, f 4 f The focal length of the optical imaging system.

2. The wavelength-independent real-time polarization imaging device based on a metasurface according to claim 1, characterized in that: The two-dimensional polarization grating x The direction is duty cycle 0.5, the phase difference is The rectangular phase grating along y Direction is blazed grating.

3. The wavelength-independent real-time polarization imaging device based on a metasurface according to claim 2, characterized in that: The one-dimensional polarization grating x Direction and y The directions are all blazed gratings.

4. The wavelength-independent real-time polarization imaging device based on a metasurface according to claim 3, characterized in that: The two-dimensional polarization grating and the one-dimensional polarization grating are both designed as geometric phase metasurfaces.

5. The wavelength-independent real-time polarization imaging device based on a metasurface according to claim 4, characterized in that: The image sensor is a CMOS.

6. A wavelength-independent real-time polarization imaging method based on a metasurface, which is implemented by the wavelength-independent real-time polarization imaging device based on a metasurface according to any one of claims 1 to 5; characterized in that The specific steps are as follows: The incident light irradiates the sample to be tested and passes through the first lens, and the light field E in Entering the two-dimensional polarization grating for modulation, diffraction splits into two left-handed circularly polarized components and two right-handed circularly polarized components , the distribution of the diffraction field of the two-dimensional polarization grating in the image plane is: in, The left and right circular polarization components are in 4 f Displacement of the image plane of the imaging system; Light Field E in2 Directly transmit to the spectrum plane located at the distance On the one-dimensional polarization grating at , the outgoing light field is diffracted and split into left-handed and right-handed circularly polarized components. , the distribution of the diffraction field of the one-dimensional polarization grating in the image plane is: in, f 4 f The focal length of the optical imaging system, is the diffraction angle of the geometric phase metasurface, i is an imaginary number; In 4 f At the image plane of the optical imaging system, that is, at the focus of the second lens, the diffraction component of the two-dimensional polarization grating and , respectively, with the diffraction components of the one-dimensional polarization grating The components completely overlap; the horizontal polarization interference intensity distribution of the left and right circular polarization components obtained after horizontal polarization analysis by the polarizer is: I 1 and I 2; From the interference intensity distribution by digital holography I 1 or I 2 Obtain the phase difference between the left and right circular polarization components , the formula is as follows: in, is the phase difference between the left and right circular polarization components of the incident light field; Calculate the Stokes parameter information of the light field to achieve full polarization imaging. The formula is as follows: 。

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