Metasurface three-dimensional holographic display method based on holographic lens

Abstract

A metasurface three-dimensional holographic display method based on holographic lenses is characterized in that on the basis of computer-generated holography, multiple layers of holographic lenses with different focal lengths are integrated into the computer-generated holography, the holographic lenses are combined with different depth images of a three-dimensional scene, the calculation time is shortened, the image quality is improved, and three-dimensional display is achieved. The three-dimensional object is cut into N depth layer plane images according to the first longitudinal depth to the Nth longitudinal depth, N is a positive integer, one depth layer plane image is overlapped with one holographic lens, and the larger the depth of the depth layer plane image is, the larger the focal length of the corresponding holographic lens is; 2, phase encoding is carried out on phase information obtained after the N depth layer plane images and the N holographic lenses are staggered and overlapped one by one through a metasurface unit structure, and hologram phase information is encoded to a metasurface structure on a metasurface substrate; and step 3, realizing three-dimensional holographic display for the three-dimensional object by using a three-dimensional metasurface holographic reconstruction system.

Description

Technical Field

[0001] The present invention relates to the field of holographic display technology, and in particular to a super-surface three-dimensional holographic display method based on a holographic lens. Background Art

[0002] Humans perceive the outside world through five senses, including vision, hearing, touch, taste and smell. A large number of studies have shown that vision is the main way for humans to perceive the content of the outside world, accounting for 80%. This shows the vital importance of vision in information acquisition. As a tool for transmitting visual information, display technology has undergone a long and continuous development process, accompanied by people's pursuit of visual information and the need to explore the visual system.

[0003] The development of display technology has experienced a series of progress from static to dynamic, from black and white to color, from standard definition to blue light. However, these advances are almost all limited to the field of two-dimensional display. With the continuous evolution of science and technology and the improvement of human needs, people naturally expect to achieve more realistic three-dimensional display effects. Therefore, it can be foreseen that future display technology will focus on the development of the three-dimensional field. Among the current three-dimensional display technologies, holographic three-dimensional display technology is widely recognized as an excellent three-dimensional display technology with broad application prospects and development potential because it can completely record and reconstruct the wavefront of objects and provide all the depth information required by the human visual system. In addition, it has become one of the focuses of global research. Metasurfaces have been widely used in three-dimensional holographic displays because of their super light field control capabilities.

[0004] With the development of computer technology, computational holography has been widely used in metasurface three-dimensional holographic displays. However, three-dimensional computational holography has the problem of large amount of computational data, which has always required a balance between computational time and image quality, severely restricting display applications. Although holographic lenses have been used in metasurface holographic displays, the traditional method has limited focal length and difficulty in composite phase encoding. The target object can only be integrated with a single holographic lens, which can only achieve two-dimensional holographic display and cannot achieve three-dimensional effects. Summary of the invention

[0005] In view of the problems of long calculation time, large data volume and poor image quality in the prior art of supersurface three-dimensional computational holography, the present invention proposes a supersurface three-dimensional holographic display method based on holographic lenses. On the basis of computational holography, multiple layers of holographic lenses with different focal lengths are integrated into it, and the holographic lenses are combined with images of three-dimensional scenes at different depths, which shortens the calculation time, improves the image quality and realizes three-dimensional display.

[0006] The technical solution of the present invention is as follows:

[0007] A three-dimensional holographic display method of a super surface based on a holographic lens, characterized by comprising the following steps:

[0008] Step 1, cutting the three-dimensional object into N depth layer plane images from the first longitudinal depth to the Nth longitudinal depth, where N is a positive integer, and one depth layer plane image is superimposed with one holographic lens, and the greater the depth of the depth layer plane image, the greater the focal length of the corresponding holographic lens;

[0009] Step 2, phase encoding the phase information of N depth layer plane images and N holographic lenses after interlaced superposition one by one using the metasurface unit structure, and encoding the hologram phase information into the metasurface structure on the metasurface substrate;

[0010] Step 3: Use a three-dimensional metasurface holographic reconstruction system to achieve three-dimensional holographic display of the three-dimensional object.

[0011] Step 2 includes generating a phase map using a superposition calculation method, wherein the phase map contains a total of 1960*1200 phase points, each of which has a phase value between 0 and 255, and encoding multiple layers of depth phase according to the superposition of the holographic lens.

[0012] The metasurface in the metasurface structure in step 2 is a geometric phase metasurface or a resonant phase metasurface or a propagation phase metasurface.

[0013] In step 2, the material used for the supersurface unit structure is silicon, amorphous silicon, gold or aluminum, and the material used for the supersurface substrate is silicon or silicon dioxide.

[0014] Step 2 includes controlling the aspect ratio, height and / or rotation angle of the metasurface unit structure to produce different phases, and matching and encoding them with the phase map generated by the superposition calculation method.

[0015] The three-dimensional metasurface holographic reconstruction system in step 3 includes a laser, a first linear polarizer, a first quarter-wave plate, a metasurface, a microscope objective, a second quarter-wave plate, a second linear polarizer and a camera connected in sequence. The output light of the laser is converted into circularly polarized light after passing through the first linear polarizer and the first quarter-wave plate, and excites the metasurface of the encoded hologram. The image is magnified by the microscope objective, the second quarter-wave plate and the second linear polarizer filter zero-order noise, and the camera receives the holographic image.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] (1) The present invention proposes to use holographic lenses with different focal lengths to integrate images with different depths of field to achieve three-dimensional holographic display, which overcomes the problem that traditional holographic lens metasurface holographic display can only display in two dimensions due to focal length limitations. It is a brand-new method.

[0018] (2) The method provided in this application reduces the amount of data required for three-dimensional holography calculations and increases the speed of calculation.

[0019] (3) The method provided in the present application reduces the inter-layer crosstalk of the three-dimensional holographic display and improves the image quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the process of implementing a super-surface three-dimensional holographic display method based on a holographic lens of the present invention. Figure 1 The method includes cutting the annular knot into four plane images according to depth, superimposing a holographic lens on one plane image, and the greater the depth of the plane image, the greater the focal length of the corresponding holographic lens. After the plane image and the holographic lens are superimposed layer by layer, the phase information of the hologram is encoded into the metasurface structure on the metasurface substrate through phase encoding. Figure 1 1- a three-dimensional object (specifically a ring knot) cut into four layers according to depth, 2- four holographic lenses with different focal lengths, 3- a metasurface unit structure (rectangular columns in different orientations) obtained by phase encoding by stacking the three-dimensional object and holographic lenses with different focal lengths layer by layer, and 4- a metasurface substrate.

[0021] Figure 2 It is a schematic diagram of the structure of a three-dimensional supersurface holographic reconstruction system involved in implementing a supersurface three-dimensional holographic display method based on a holographic lens of the present invention. Figure 2 The method includes a laser, a first linear polarizer, a first quarter wave plate, a metasurface, a microscope objective, a second quarter wave plate, a first linear polarizer and a camera which are connected in sequence. Figure 2 21 - laser, 22 - first linear polarizer, 23 - first quarter wave plate, 24 - metasurface, 25 - microscope objective, 26 - second quarter wave plate, 27 - first linear polarizer, 28 - camera.

[0022] Figure 3 Schematic diagram of three holographic lenses with different focal lengths. Figure 3 From left to right in the figure are 31-holographic lens with a focal length of 400um, 32-holographic lens with a focal length of 700um, and 33-holographic lens with a focal length of 1000um.

[0023] Figure 4 It is an image of a ring segment of a three-dimensional target display object. Figure 4 The annular segment image in the image has xy plane information and z direction depth information, and can be cut in layers according to depth.

[0024] Figure 5 It is a three-dimensional holographic phase image of a metasurface based on a holographic lens involving three layers of depth of field.

[0025] Figure 6It is a three-dimensional holographic reconstruction of a metasurface based on a holographic lens involving three layers of depth of field. Figure 6 From left to right in the figure are 61 - holographic reconstructed image at a focal length of 400um, 62 - holographic reconstructed image at a focal length of 700um, and 63 - holographic reconstructed image at a focal length of 1000um.

[0026] Figure 7 It is a three-dimensional holographic phase image of a metasurface based on a holographic lens involving seven layers of depth of field.

[0027] Figure 8 It is a three-dimensional holographic reconstruction of a metasurface based on a holographic lens involving seven layers of depth of field. Figure 8 From left to right in the figure are 81 - the holographic reconstruction image when the focal length is 400um, 82 - the holographic reconstruction image when the focal length is 500um, 83 - the holographic reconstruction image when the focal length is 600um, 84 - the holographic reconstruction image when the focal length is 700um, 85 - the holographic reconstruction image when the focal length is 800um, 86 - the holographic reconstruction image when the focal length is 900um, and 87 - the holographic reconstruction image when the focal length is 1000um. DETAILED DESCRIPTION

[0028] Below is the attached figure ( Figure 1-Figure 8 ) and Examples illustrate the present invention.

[0029] Figure 1 It is a schematic diagram of the process of implementing a super-surface three-dimensional holographic display method based on a holographic lens of the present invention. Figure 2 It is a schematic diagram of the structure of a three-dimensional supersurface holographic reconstruction system involved in implementing a supersurface three-dimensional holographic display method based on a holographic lens of the present invention. Figure 3 Schematic diagram of three holographic lenses with different focal lengths. Figure 4 It is an image of a ring segment of a three-dimensional target display object. Figure 5 It is a three-dimensional holographic phase image of a metasurface based on a holographic lens involving three layers of depth of field. Figure 6 It is a three-dimensional holographic reconstruction of a metasurface based on a holographic lens involving three layers of depth of field. Figure 7 It is a three-dimensional holographic phase image of a metasurface based on a holographic lens involving seven layers of depth of field. Figure 8 This is a 3D holographic reconstruction of a metasurface based on a holographic lens involving seven levels of depth of field. Figures 1 to 8As shown, a metasurface three-dimensional holographic display method based on a holographic lens comprises the following steps: step 1, cutting a three-dimensional object into N depth layer plane images from a first longitudinal depth to an Nth longitudinal depth, N being a positive integer, and superimposing one depth layer plane image with one holographic lens, and the greater the depth of the depth layer plane image, the greater the focal length of the corresponding holographic lens; step 2, using a metasurface unit structure to phase encode the phase information after the N depth layer plane images are staggered and superimposed one by one with the N holographic lenses, and encoding the hologram phase information onto the metasurface structure on the metasurface substrate; step 3, using a three-dimensional metasurface holographic reconstruction system to realize a three-dimensional holographic display of the three-dimensional object.

[0030] Step 2 includes generating a phase map using a superposition calculation method, wherein the phase map contains a total of 1960*1200 phase points, each phase point has a phase value from 0 to 255, and the multi-layer deep phase is encoded according to the superposition of the holographic lens. The metasurface in the metasurface structure in step 2 is a geometric phase metasurface, a resonant phase metasurface, or a propagation phase metasurface. The material used for the metasurface unit structure in step 2 is silicon, amorphous silicon, gold, or aluminum, and the material used for the metasurface substrate is silicon or silicon dioxide. Step 2 includes controlling the aspect ratio, height, and / or rotation angle of the metasurface unit structure to produce different phases, and matching and encoding with the phase map generated using the superposition calculation method.

[0031] The three-dimensional metasurface holographic reconstruction system in step 3 includes a laser 21, a first linear polarizer 22, a first quarter-wave plate 23, a metasurface 24, a microscope objective 25, a second quarter-wave plate 26, a second linear polarizer 27 and a camera 28 connected in sequence. The output light of the laser 21 is converted into circularly polarized light after passing through the first linear polarizer 22 and the first quarter-wave plate 23, and excites the metasurface 24 encoding the hologram. The image is magnified by the microscope objective 25, the second quarter-wave plate 26 and the second linear polarizer 27 filter the zero-order noise, and the camera 28 receives the holographic image.

[0032] The present invention relates to a supersurface three-dimensional holographic display method based on holographic lenses. The technical process of the method is to integrate multiple layers of holographic lenses with different focal lengths into the method on the basis of computational holography, combine the holographic lenses with different depth images of the three-dimensional scene, and encode them together on a supersurface with ultra-high light field modulation capability, and use a supersurface three-dimensional holographic reconstruction system to achieve three-dimensional holographic display. The multi-focal length holographic lens design and layer-by-layer superposition method have been used to break through the difficulty that traditional holographic lens supersurface holography can only display in two dimensions, and solve the problems of long calculation time, large data volume, and poor image quality of supersurface three-dimensional computational holography in the prior art.

[0033] A metasurface three-dimensional holographic display method based on holographic lenses. The process of the method is that when calculating the hologram, images of different depths of the three-dimensional scene are added to holographic lenses with different focal lengths, and then multi-depth hologram superposition calculations are performed. The obtained hologram phase information is encoded into the metasurface unit structure, and a three-dimensional metasurface holographic reconstruction system is used to realize three-dimensional metasurface holographic display.

[0034] The 3D holographic display method of the super surface based on the holographic lens is as follows:

[0035] (1) Cut the three-dimensional object into different depth layers according to depth, superimpose the image on each depth layer with a holographic lens, the focal length of the holographic lens corresponds to the depth of the image, and calculate the phase information after superposition;

[0036] (2) Encoding phase information using the unit structure of the metasurface;

[0037] (3) Use the three-dimensional metasurface holographic reconstruction system to realize three-dimensional holographic display.

[0038] The method of computational holography is:

[0039] (1) Cut the 3D scene based on depth to form images at different depths;

[0040] (2) Adding holographic lenses with different focal lengths to holograms at different depths is used to reduce the amount of algorithm data and inter-layer crosstalk, thereby improving the quality of 3D holographic display;

[0041] (3) Multi-depth hologram superposition calculation to generate phase map.

[0042] The described super surface encoding method comprises:

[0043] (1) The metasurface may be any one of a geometric phase metasurface, a resonant phase metasurface, and a propagation phase metasurface;

[0044] (2) The unit structure material of the metasurface can be any one of silicon, amorphous silicon, gold, and aluminum, and the substrate of the metasurface can be silicon dioxide or silicon;

[0045] (3) By controlling the aspect ratio, height, and rotation angle of the metasurface unit structure, it produces different phases and matches the calculated phase map for encoding.

[0046] The three-dimensional metasurface holographic reconstruction system is as follows: a three-dimensional holographic reconstruction system is constructed by using a laser, a linear polarizer, a quarter-wave plate, a microscope objective, a camera, and a metasurface. The output light of the laser is converted into circularly polarized light after passing through a linear polarizer and a quarter-wave plate to excite the metasurface encoding a hologram, the image is magnified through a microscope objective, the zero-order noise is filtered using a quarter-wave plate and a linear polarizer, and the holographic image is received by a camera.

[0047] refer to Figure 1 The three-dimensional object "ring knot" is cut into four plane images according to depth, and the image on each depth layer is superimposed on a holographic lens. The focal length of the holographic lens corresponds to the depth of the image. The phase information after superposition is calculated and encoded on the metasurface unit structure. The number of layers can be set arbitrarily as needed. Figure 2 It is a three-dimensional metasurface holographic reconstruction system. The laser's outgoing light is converted into circularly polarized light after passing through a linear polarizer and a quarter-wave plate, which excites the metasurface of the encoded hologram. The image is magnified through a microscope objective, and the zero-order noise is filtered using a quarter-wave plate and a linear polarizer. The holographic image is received by a camera. Figure 3 These are holographic lenses with different focal lengths generated in Example 1. Figure 4-Figure 6 This is the experimental result of the supersurface three-dimensional holography (three-layer depth of field) based on the holographic lens in Example 2. Figure 7-Figure 8 This is the experimental result of the supersurface three-dimensional holography (seven layers of depth of field) based on the holographic lens in Example 3.

[0048] Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that, unless otherwise specified, the technical terms or scientific terms used in the present invention should be the common meanings understood by those skilled in the art to which the present invention belongs.

[0049] In order to make the technical objectives, technical solutions and beneficial effects of the present invention clearer, a metasurface three-dimensional holographic display method based on a holographic lens provided according to an embodiment of the present invention is described below in conjunction with the accompanying drawings and specific exemplary embodiments.

[0050] Example 1: Holographic lenses with different focal lengths

[0051] The steps include:

[0052] (1) Figure 3 As shown, holographic lenses with a focal length of 400um (marked 31), a focal length of 700um (marked 32), and a focal length of 1000um (marked 33) are designed.

[0053] (2) The smaller the focal length, the larger the central circle, and the fewer the number of rings for the same area; the larger the focal length, the smaller the central circle, and the more the number of rings for the same area.

[0054] Example 2: Metasurface 3D holography based on holographic lens (three-layer depth of field)

[0055] The steps include:

[0056] (1) Target object ring segment ( Figure 4 ) is a three-dimensional object. In addition to the xy plane, the image also has depth information along the z direction. It is cut into three layers according to the depth.

[0057] (2) The three layers of images with different depths of field after cutting are respectively superimposed with three holographic lenses with different focal lengths, where the focal lengths of the holographic lenses are 400um, 700um, and 1000um, respectively.

[0058] (3) Using the superposition calculation method, a phase diagram is generated, such as Figure 5 As shown, the calculation time is only 0.36 seconds. The phase map contains a total of 1960*1200 phase points, and each phase point has a phase value between 0 and 255. Due to the superposition of holographic lenses, the multi-layer deep phase is effectively encoded, and an obvious phase mutation effect appears in the center of the phase map.

[0059] (4) The unit structure of the metasurface is a nanocolumn structure made of amorphous silicon. The nanocolumn is 200 nm long, 100 nm wide, and 500 nm high. It is rotated at different angles to provide phase contrast with the holographic phase. Figure 1 The nanorods are fabricated on a silicon dioxide substrate with a consistent phase.

[0060] (5) Using the holographic reconstruction system to generate holographic display images, such as Figure 6 As shown, the laser light with a wavelength of 808nm is converted into circularly polarized light after passing through a linear polarizer and a quarter-wave plate, which excites the metasurface of the encoded hologram, the image is magnified through a microscope objective, the zero-order noise is filtered using a quarter-wave plate and a linear polarizer, and the holographic image is received by a camera.

[0061] (6) By moving the camera forward and backward to receive holographic images at different depths, the image at the first depth of the annular segment is observed at a focal length of 61, the image at the second depth of the annular segment is observed at a focal length of 62, and the image at the third depth of the annular segment is observed at a focal length of 63. The various layers are spliced ​​together to present a three-dimensional holographic display effect in the object space. The holographic image of each layer is clear and there is no crosstalk between layers.

[0062] Example 3: Metasurface 3D Holography Based on Holographic Lens (Seven-layer Depth of Field)

[0063] The steps include:

[0064] (1) Ring segmentation of the three-dimensional target object ( Figure 4 ) The depth in the z direction is used as a clue to perform layered cutting, and the layered cutting is divided into seven layers.

[0065] (2) The seven layers of images with different depths of field after cutting are respectively superimposed with seven holographic lenses with different focal lengths. The focal lengths of the holographic lenses are 400um, 500um, 600um, 700um, 800um, 900um, and 1000um, respectively.

[0066] (3) Using the superposition calculation method, a phase diagram is generated, such as Figure 7 As shown, the calculation time is only 0.81 seconds. The phase map contains a total of 1600*1200 phase points, and each phase point has a phase value between 0-255. Due to the superposition of holographic lenses, the multi-layer deep phase is effectively encoded. Due to the large number of layers, the phase mutation area in the center of the phase map becomes larger.

[0067] (4) The unit structure of the metasurface is a nanocylindrical structure made of gold. The nanocylinder is 600nm high and has a diameter of 100nm-300nm. Different diameters are used to provide a phase consistent with the holographic phase image. The unit structure of the metasurface is processed on a silicon substrate.

[0068] (5) Using the holographic reconstruction system to generate holographic display images, such as Figure 8 As shown, the laser light with a wavelength of 795nm is converted into circularly polarized light after passing through a linear polarizer and a quarter-wave plate, which excites the metasurface of the encoded hologram, the image is magnified through a microscope objective, the zero-order noise is filtered using a quarter-wave plate and a linear polarizer, and the holographic image is received by a camera.

[0069] (6) By moving the camera forward and backward to receive holographic images at different depths, an image at the first depth of the annular segment is observed at focal length 81, an image at the second depth of the annular segment is observed at focal length 82, an image at the third depth of the annular segment is observed at focal length 83, an image at the fourth depth of the annular segment is observed at focal length 84, an image at the fifth depth of the annular segment is observed at focal length 85, an image at the sixth depth of the annular segment is observed at focal length 86, and an image at the seventh depth of the annular segment is observed at focal length 87. The various layers are spliced ​​together to present a three-dimensional holographic display effect in the object space. The holographic image of each layer is clear without crosstalk between layers. As the number of layers increases, the three-dimensional depth information increases, and the holographic display effect is significantly improved.

[0070] The contents not described in detail in the specification of the present invention belong to the prior art known to the professional and technical personnel in this field.

[0071] The embodiments described above are only preferred embodiments of the present invention and do not limit the present invention in any form. Any technician familiar with the art, without departing from the scope of the technical solution of the present invention, can make more possible changes and modifications to the technical solution of the present invention using the technical content disclosed above, or the modifications are all equivalent embodiments of the present invention. Therefore, all equivalent and equivalent changes made according to the ideas of the present invention without departing from the content of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0072] It should be understood that the foregoing only describes some embodiments, and changes, modifications, additions and / or variations may be made without departing from the scope and essence of the disclosed embodiments, which are illustrative rather than restrictive. In addition, the described embodiments relate to what are currently considered to be the most practical and preferred embodiments, and it should be understood that the embodiments should not be limited to the disclosed embodiments, but rather are intended to cover different modifications and equivalent arrangements included within the essence and scope of the embodiments. In addition, the various embodiments described above may be used in conjunction with other embodiments, such as aspects of one embodiment may be combined with aspects of another embodiment to achieve yet another embodiment. In addition, each independent feature or component of any given component may constitute another embodiment.

[0073] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention, and should all be included in the scope of the claims and specification of the present invention.

Claims

1. A three-dimensional holographic display method of a metasurface based on a holographic lens, characterized in that: The following steps are involved: Step 1, cutting the three-dimensional object into N depth layer plane images from the first longitudinal depth to the Nth longitudinal depth, where N is a positive integer, and one depth layer plane image is superimposed with one holographic lens, and the greater the depth of the depth layer plane image, the greater the focal length of the corresponding holographic lens; Step 2, phase encoding the phase information of N depth layer plane images and N holographic lenses after interlaced superposition one by one using the metasurface unit structure, and encoding the hologram phase information into the metasurface structure on the metasurface substrate; Step 3: Use a three-dimensional metasurface holographic reconstruction system to achieve three-dimensional holographic display of the three-dimensional object.

2. The method for three-dimensional holographic display of a supersurface based on a holographic lens according to claim 1, characterized in that: Step 2 includes generating a phase map using a superposition calculation method, wherein the phase map contains a total of 1960*1200 phase points, each of which has a phase value between 0 and 255, and encoding multiple layers of depth phase according to the superposition of the holographic lens.

3. The method for three-dimensional holographic display of a supersurface based on a holographic lens according to claim 1, characterized in that: The metasurface in the metasurface structure in step 2 is a geometric phase metasurface or a resonant phase metasurface or a propagation phase metasurface.

4. The method for three-dimensional holographic display of a supersurface based on a holographic lens according to claim 1, characterized in that: In step 2, the material used for the supersurface unit structure is silicon, amorphous silicon, gold or aluminum, and the material used for the supersurface substrate is silicon or silicon dioxide.

5. The method for three-dimensional holographic display of a supersurface based on a holographic lens according to claim 1, characterized in that: Step 2 includes controlling the aspect ratio, height and / or rotation angle of the metasurface unit structure to produce different phases, and matching and encoding them with the phase map generated by the superposition calculation method.

6. The method for three-dimensional holographic display of a supersurface based on a holographic lens according to claim 1, characterized in that: The three-dimensional metasurface holographic reconstruction system in step 3 includes a laser, a first linear polarizer, a first quarter-wave plate, a metasurface, a microscope objective, a second quarter-wave plate, a second linear polarizer and a camera connected in sequence. The output light of the laser is converted into circularly polarized light after passing through the first linear polarizer and the first quarter-wave plate, and excites the metasurface of the encoded hologram. The image is magnified by the microscope objective, the second quarter-wave plate and the second linear polarizer filter zero-order noise, and the camera receives the holographic image.

Images