Optical devices, holographic imaging systems and methods based on photosensitive liquid crystal superstructures

Abstract

This invention discloses an optical device, holographic imaging system, and method based on a photosensitive liquid crystal superstructure. The optical device, used to store holographic imaging patterns, includes a first substrate, a second substrate, and a photosensitive cholesteric liquid crystal layer located between the first and second substrates, all disposed opposite each other. A first alignment layer is disposed on the side of the first substrate facing the second substrate, and a second alignment layer is disposed on the side of the second substrate facing the first substrate. The first and second alignment layers have the same orientation direction. Each of the first and second alignment layers includes multiple sub-regions arranged in an array, and each sub-region stores a holographic phase structure, thus forming a photosensitive liquid crystal superstructure storing the holographic phase structure. The optical device provided by this invention achieves the storage and reproduction of large-capacity color holographic imaging patterns through the photosensitive liquid crystal superstructure, overcoming the limitations of traditional holographic imaging and realizing the imaging of multiple color holographic patterns.

Description

Technical Field

[0001] This invention relates to the fields of liquid crystal microstructures and holographic imaging technology, and in particular to an optical device, holographic imaging system and method based on a photosensitive liquid crystal superstructure. Background Technology

[0002] Holographic imaging technology has wide applications in fields such as industrial non-destructive testing, holographic microscopy, and interferometry. It has not only promoted technological progress in fields such as industry and medicine, but also brought about a revolution in human visual experience.

[0003] However, traditional holographic imaging technology suffers from limitations in materials and processes, resulting in restricted information capacity, a single operating wavelength, and fixed holographic imaging patterns, which limits its application and development. Optical addressing technology offers advantages over electrical addressing technology, such as being non-contact and having strong parallel capabilities. However, traditional optical addressing technology involves photoelectric and electro-optical conversions in applications such as optical addressing potential sensors and optical addressing spatial light modulators, which increases system complexity and reduces system flexibility. Summary of the Invention

[0004] This invention provides an optical device, holographic imaging system, and method based on a photosensitive liquid crystal superstructure. The optical device achieves the storage and reproduction of large-capacity color holographic imaging patterns by relying on the photosensitive liquid crystal superstructure, breaking through the limitations of traditional holographic imaging and realizing the imaging of multiple color holographic patterns.

[0005] According to one aspect of the present invention, an optical device based on a photosensitive liquid crystal superstructure is provided for storing holographic imaging patterns, the optical device comprising a first substrate, a second substrate disposed opposite to each other, and a photosensitive cholesteric liquid crystal layer located between the first substrate and the second substrate;

[0006] Wherein, a first alignment layer is provided on the side of the first substrate facing the second substrate, and a second alignment layer is provided on the side of the second substrate facing the first substrate, and the first alignment layer and the second alignment layer have the same alignment direction;

[0007] The first alignment layer and the second alignment layer include multiple sub-regions arranged in an array, each of which stores a holographic phase structure, so that the photosensitive cholesteric liquid crystal layer forms a photosensitive liquid crystal superstructure storing a holographic phase structure.

[0008] Optionally, the photosensitive cholesteric liquid crystal layer includes photosensitive chiral molecules and cholesteric liquid crystal. Under ultraviolet light stimulation, the photosensitive chiral molecules undergo a trans-cis conversion, resulting in a decrease in helical twisting force, an increase in the pitch of the cholesteric liquid crystal, and a larger central wavelength of reflected light. Under green light stimulation, the photosensitive chiral molecules undergo a cis-trans conversion, resulting in an increase in helical twisting force, a decrease in the pitch of the cholesteric liquid crystal, and a smaller central wavelength of reflected light.

[0009] Optionally, it also includes spacer particles disposed between the first substrate and the second substrate, the spacer particles being used to support the first substrate and the second substrate to form the filling space of the photosensitive cholesteric liquid crystal layer.

[0010] Optionally, the holographic phase structure is calculated using the Gerchberg-Saxton algorithm.

[0011] According to another aspect of the present invention, a holographic imaging system is provided, comprising a color hologram optical addressing unit, a color hologram imaging unit, and the aforementioned optical device based on a photosensitive liquid crystal superstructure, wherein the color hologram optical addressing unit and the color hologram imaging unit are respectively disposed on both sides of the optical device;

[0012] The color hologram optical addressing unit is used to adjust the working wavelength of the region corresponding to the target color holographic imaging in the photosensitive liquid crystal superstructure of the optical device, and the color hologram imaging unit is used to realize color holographic imaging with multi-wavelength readout light.

[0013] Optionally, the color hologram optical addressing unit includes an LED light source, a first lens, a second lens, an aperture and a digital micromirror device arranged sequentially along the optical axis in the first direction, a beam splitter, a third lens arranged sequentially along the second direction, and a first receiving screen arranged in the third direction. The first direction and the second direction intersect, and the first direction and the third direction are opposite.

[0014] The light beam output by the LED light source passes sequentially through the first lens, the second lens, and the aperture, and is reflected by the digital micromirror device. The reflected beam passes through the beam splitter and the third lens, and is reflected by the optical device. The reflected beam is then reflected by the beam splitter after passing through the third lens and is received by the first receiving screen.

[0015] Optionally, the LED light source is used to output an ultraviolet beam or a green beam, and the digital micromirror device modulates the output beam of the LED light source into an array addressing beam corresponding to the array structure of the photosensitive liquid crystal superstructure, and controls the array addressing beam to independently regulate each array sub-region.

[0016] Optionally, the color hologram optical addressing unit uses a step-by-step addressing method to achieve color holographic addressing;

[0017] The digital micromirror device is controlled to switch multiple optical masks, and the switching of multiple optical masks generates multiple array addressing lights. By switching optical masks to switch different array addressing lights in each addressing step, independent wavelength adjustment of different array sub-regions of the photosensitive liquid crystal superstructure is achieved, thereby realizing optical addressing of color holograms.

[0018] Optionally, the color hologram imaging unit includes a supercontinuum laser source, a polarizer, a fourth lens, a fifth lens, a sixth lens, and a second receiving screen arranged sequentially along the fourth direction, wherein the fourth direction and the fifth direction intersect.

[0019] The multi-wavelength readout light output from the supercontinuous laser source passes sequentially through the polarizer, the fourth lens, and the fifth lens before being incident on the optical device. After being optically addressed, the optical device reflects the light, and the reflected light passes through the sixth lens to project a color holographic image onto the second receiving screen.

[0020] According to another aspect of the present invention, a holographic imaging method is provided, applicable to the above-described holographic imaging system, the holographic imaging method comprising:

[0021] The holographic phase structure of the holographic imaging pattern was calculated using the Gerchberg-Saxton algorithm.

[0022] The holographic phase structure is stored in a photosensitive cholesteric liquid crystal in an array arrangement to form an optical device based on a photosensitive liquid crystal superstructure.

[0023] Multi-wavelength color hologram addressing is achieved through a color hologram optical addressing unit;

[0024] Color hologram imaging is achieved through a color hologram imaging unit;

[0025] By switching optical masks using digital micromirror devices, switching addressing light wavelengths using LED light sources, and switching multi-wavelength readout light using supercontinuous laser light sources, the switching of different color hologram images can be achieved.

[0026] The optical device based on a photosensitive liquid crystal superstructure provided in this invention is used to store holographic imaging patterns. The optical device includes a first substrate, a second substrate, and a photosensitive cholesteric liquid crystal layer located between the first and second substrates, all disposed opposite each other. A first alignment layer is disposed on the side of the first substrate facing the second substrate, and a second alignment layer is disposed on the side of the second substrate facing the first substrate. The first and second alignment layers have the same orientation direction. The first and second alignment layers include multiple sub-regions arranged in an array, each sub-region storing a holographic phase structure, thus forming a photosensitive liquid crystal superstructure storing holographic phase structures. The technical solution of this invention utilizes the photostimulation response characteristics of the photosensitive cholesteric liquid crystal, whose Bragg reflection band undergoes a red / blue shift under light stimulation, covering an ultra-wide wavelength range from visible to near-infrared, laying the foundation for dynamic light field manipulation. Furthermore, the Bragg reflection light of the photosensitive cholesteric liquid crystal carries geometric phase information, providing a new platform for the development of pure phase holographic imaging. Photosensitive materials can be stimulated by light and their holographic light fields can be modulated. They are expected to provide new ideas and methods for the development of all-optical modulation, enabling the storage and reproduction of large-capacity color holographic imaging patterns, breaking through the limitations of traditional holographic imaging, and realizing the imaging of multiple color holographic patterns.

[0027] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of an optical device structure based on a photosensitive liquid crystal superstructure provided in an embodiment of the present invention;

[0030] Figure 2 A top view schematic diagram of an optical device provided in an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of the holographic phase structure corresponding to a target holographic imaging pattern provided in an embodiment of the present invention;

[0032] Figure 4 The photostimulation response spectrum characterization diagram of the dextrorotatory photosensitive cholesteric liquid crystal provided in the embodiments of the present invention;

[0033] Figure 5Photomicrographs of the photosensitive cholesteric liquid crystal in response to light stimulation and macroscopic photographs of the photosensitive cholesteric liquid crystal after local independent addressing light stimulation are provided in the embodiments of the present invention.

[0034] Figure 6 This is a schematic diagram of the structure of a holographic imaging system provided in an embodiment of the present invention;

[0035] Figure 7 This is a schematic flowchart of a holographic imaging method provided in an embodiment of the present invention;

[0036] Figure 8 This is a schematic diagram of the step-by-step optical addressing process provided in an embodiment of the present invention;

[0037] Figure 9 Five switchable far-field color holographic diffraction spot patterns and corresponding near-field photosensitive liquid crystal structure color macroscopic photographs are provided for embodiments of the present invention. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0039] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0040] Figure 1 This invention provides a schematic diagram of an optical device structure based on a photosensitive liquid crystal superstructure, used for storing holographic imaging patterns. (Reference) Figure 1The optical device includes a first substrate 10, a second substrate 20 disposed opposite to each other, and a photosensitive cholesteric liquid crystal layer 30 located between the first substrate 10 and the second substrate 20. A first alignment layer 40 is disposed on the side of the first substrate 10 facing the second substrate 20, and a second alignment layer 50 is disposed on the side of the second substrate 20 facing the first substrate 10. The first alignment layer 40 and the second alignment layer 50 have the same alignment direction. The first alignment layer 40 and the second alignment layer 50 include multiple sub-regions arranged in an array, each sub-region storing a holographic phase structure, thus forming a photosensitive liquid crystal superstructure storing a holographic phase structure in the photosensitive cholesteric liquid crystal layer 30. For example, the first alignment layer 40 and the second alignment layer 50 include 25 sub-regions arranged in a 5×5 array structure. Figure 2 This is a top view schematic diagram of an optical device provided in an embodiment of the present invention, schematically showing the surface liquid crystal molecule arrangement of a photosensitive cholesteric liquid crystal. Each sub-region in the array structure stores a holographic phase structure, forming a photosensitive liquid crystal superstructure storing a large capacity of holographic phase structures. The surface liquid crystal molecule arrangement of the photosensitive cholesteric liquid crystal is determined by the first alignment layer 40 and the second alignment layer 50, and is schematically presented as a 5×5 array structure arrangement in the top view. The surface liquid crystal molecule arrangement of each array sub-region represents a holographic phase structure. It can be understood that... Figure 2 The image is merely an illustrative representation of the surface liquid crystal molecule arrangement of a photosensitive cholesteric liquid crystal, and does not represent the actual size and arrangement.

[0041] Optionally, the photosensitive cholesteric liquid crystal layer includes photosensitive chiral molecules and cholesteric liquid crystal. Under ultraviolet light stimulation, the photosensitive chiral molecules undergo a trans-cis conversion, resulting in a decrease in helical twisting force, an increase in the pitch of the cholesteric liquid crystal, and a larger central wavelength of reflected light. Under green light stimulation, the photosensitive chiral molecules undergo a cis-trans conversion, resulting in an increase in helical twisting force, a decrease in the pitch of the cholesteric liquid crystal, and a decrease in the central wavelength of reflected light. Figure 1 As shown, the photosensitive liquid crystal superstructure exhibits four different pitch arrangements at different positions.

[0042] Optionally, the holographic phase structure is calculated using the Gerchberg-Saxton algorithm.

[0043] The Gerchberg-Saxton (GS) algorithm is an iterative algorithm for reconstructing missing phase information, widely used in optical imaging, digital holography, and signal processing. This algorithm recovers missing phase information by alternately propagating information between the object plane and the image plane, progressively optimizing the reconstructed object phase. Figure 3 This is a schematic diagram of the holographic phase structure corresponding to a target holographic imaging pattern provided in an embodiment of the present invention. (Reference) Figure 3In one embodiment of the present invention, the holographic imaging pattern comprises five images of humans at different stages of growth, five images of trees at different stages of growth, and one image of the sun. The corresponding holographic phase structure is obtained by the GS algorithm. It should be noted that the aforementioned holographic phase structure can be designed and switched according to actual needs in other embodiments to achieve the desired target pattern imaging.

[0044] Continue to refer to Figure 1 Optionally, the optical device also includes spacer particles 60 disposed between the first substrate 10 and the second substrate 20. The spacer particles 60 are used to support the first substrate 10 and the second substrate 20 to form the filling space of the photosensitive cholesteric liquid crystal layer 30.

[0045] Understandable Figure 1 The image only illustrates the positional relationship of the spacer particles 60 for supporting the first substrate 10 and the second substrate 20, and does not represent their actual size and proportions. Optionally, the spacer particles 60 may include quartz spheres or quartz pillars, and can be designed according to actual conditions in specific implementations. Optionally, along the direction perpendicular to the plane of the first substrate 10, the extension length of the spacer particles 60 is greater than or equal to 10 times the pitch of the liquid crystal molecules in the photosensitive cholesteric liquid crystal layer 30.

[0046] Photosensitive cholesteric liquid crystals exhibit photostimulation-responsive properties, for example... Figure 4 The image shows the photostimulation response spectrum of a dextrorotatory photosensitive cholesteric liquid crystal provided in an embodiment of the present invention. (Reference) Figure 4 Optionally, when the incident light is linearly polarized, the Bragg reflectance band of the dextrorotatory photosensitive cholesteric liquid crystal will redshift under ultraviolet light stimulation, and different stimulation times will result in different degrees of redshift in the Bragg reflectance band. At 4mW / cm² 2 Under ultraviolet light stimulation, the stimulation time can cover the visible to near-infrared band (400nm to 2000nm) within 0 to 52 seconds; among them, for the visible light band, optionally, when the incident light is right-handed circularly polarized light (RCP), the Bragg reflection band of the right-handed photosensitive cholesteric liquid crystal can achieve extremely high reflectivity and cover the visible band (400nm to 800nm) within 13 seconds.

[0047] It should be noted that the embodiments of the present invention only exemplarily show the photostimulation response spectrum characterization diagram of the dextrorotatory photosensitive cholesteric liquid crystal, but are not intended to limit the photosensitive cholesteric liquid crystal provided by the present invention. In other embodiments, photosensitive cholesteric liquid crystals with other photostimulation response properties can be prepared according to actual needs, and the Bragg reflection band can be adjusted accordingly.

[0048] For example, Figure 5These are photostimulation response micrographs of photosensitive cholesteric liquid crystals and macroscopic images of photosensitive cholesteric liquid crystals after locally independently addressed photostimulation, provided as embodiments of the present invention. (Reference) Figure 5 This photosensitive cholesteric liquid crystal can exhibit different structural colors under light stimulation at different times, and the structural color can be adjusted back and forth within the visible light range under ultraviolet / green addressable light stimulation. Specifically, after addressable light stimulation, different regions of the photosensitive cholesteric liquid crystal are stimulated for different times, thus exhibiting different structural colors. Optionally, different regions of the photosensitive cholesteric liquid crystal can be combined into a colored English letter "Growth" pattern after localized independent addressable light stimulation.

[0049] It should be noted that the embodiments of the present invention only exemplarily show a macroscopic image of a photosensitive cholesteric liquid crystal after local independent addressing light stimulation, but are not intended to limit the array addressing light provided by the present invention. In other embodiments, other addressing lights can be prepared according to actual needs, which can adjust the photosensitive cholesteric liquid crystal accordingly, including but not limited to growth patterns.

[0050] The technical solution of this invention utilizes the photostimulation response characteristics of photosensitive cholesteric liquid crystals. The Bragg reflection band of these liquid crystals undergoes a red / blue shift under light stimulation, covering an ultra-wide wavelength range from visible to near-infrared, laying the foundation for dynamic light field manipulation. Furthermore, the Bragg reflection light from the photosensitive cholesteric liquid crystals carries geometric phase information, providing a new platform for the development of pure phase holographic imaging. The photosensitive material can be both stimulated and manipulated by light to create a holographic light field, potentially providing new ideas and methods for the development of all-optical manipulation, enabling the storage and reproduction of large-capacity color holographic imaging patterns, breaking through the limitations of traditional holographic imaging, and achieving the imaging of multiple color holographic patterns.

[0051] Based on the optical devices provided in the above embodiments, this invention also provides a holographic imaging system. Figure 6 This is a schematic diagram of the structure of a holographic imaging system provided in an embodiment of the present invention, with reference to... Figure 6 The holographic imaging system includes a color hologram optical addressing unit 100, a color hologram imaging unit 200, and an optical device 300 based on a photosensitive liquid crystal superstructure provided in the above embodiment. The color hologram optical addressing unit 100 and the color hologram imaging unit 200 are respectively disposed on both sides of the optical device 300. The color hologram optical addressing unit 100 is used to adjust the working wavelength of the region corresponding to the target color holographic imaging in the photosensitive liquid crystal superstructure of the optical device 300, and the color hologram imaging unit 200 is used to realize color holographic imaging with multi-wavelength readout light.

[0052] Optionally, the color hologram optical addressing unit 100 includes an LED light source 101, a first lens 102, a second lens 103, an aperture 104, and a digital micromirror device 105 arranged sequentially along a first direction (positive y-axis direction) and a beam splitter 106, a third lens 107 arranged sequentially along a second direction (negative z-axis direction), and a first receiving screen 108 arranged along a third direction (negative y-axis direction). The first and second directions intersect, and the first and third directions are opposite. The light beam output by the LED light source 101 passes sequentially through the first lens 102, the second lens 103, and the aperture 104, and is reflected by the digital micromirror device 105. The reflected light beam from the digital micromirror device 105 passes through the beam splitter 106 and the third lens 107, and is reflected by the optical device 300. The reflected light beam from the optical device 300 passes through the third lens 107, is reflected by the beam splitter 106, and is received by the first receiving screen 108.

[0053] The LED light source is a UV / green LED, used to emit UV or green light, such as 365nm UV light or 532nm green light. The digital micromirror device 105 modulates the output beam of the LED light source 101 into an array addressing beam corresponding to the array structure of the photosensitive liquid crystal superstructure. It controls the array addressing beam to independently regulate each array sub-region, controlling the light intensity of the addressing beam array sub-region to be 0 or 1. Here, 1 indicates that the micromirrors in the digital micromirror device 105 reflect the addressing beam to the optical device, and 0 indicates that the addressing beam is reflected outside the optical device. The array addressing beam adjusts the working wavelength of the corresponding target color holographic imaging region in the photosensitive liquid crystal superstructure. The array addressing beam, according to the LED light source output beam, passes sequentially through the first lens 102, the second lens 103, and the aperture 104 before being reflected by the digital micromirror device 105. The array addressing beam then passes through the beam splitter 106 and the third lens 107 before illuminating the photosensitive liquid crystal superstructure. Based on the photostimulation response characteristics of the photosensitive cholesteric liquid crystal in the optical device 300, ultraviolet / green array addressing light is used to adjust the positions of different array sub-structures and different operating wavelengths of the photosensitive liquid crystal superstructure. Optionally, the color hologram optical addressing unit 100 adopts a step-by-step addressing method to realize color holographic addressing; the digital micromirror device 105 is controlled to switch multiple optical masks, such as optical masks 1, 2...n. The switching of multiple optical masks generates multiple array addressing lights 1, 2...n. By switching the optical masks, different array addressing lights are switched in each addressing step, so as to realize independent wavelength adjustment of different array sub-regions of the photosensitive liquid crystal superstructure and realize color hologram optical addressing.

[0054] Optionally, the color holographic imaging unit 200 includes a supercontinuum laser source 201, a polarizer 202, a fourth lens 203, a fifth lens 204 arranged sequentially along the fourth direction (z-axis angle -10°), a sixth lens 205 arranged along the fifth direction (z-axis angle +10°), and a second receiving screen 206. The fourth and fifth directions intersect. The multi-wavelength readout light output from the supercontinuum laser source 201 passes sequentially through the polarizer 202, the fourth lens 203, and the fifth lens 204 before being incident on the optical device 300. After being optically addressed, the optical device 300 reflects the light, and the reflected light passes through the sixth lens 205 to project the color holographic image onto the second receiving screen 206.

[0055] Among them, the supercontinuum laser source 201 is used to output supercontinuum lasers covering the visible light and near-infrared bands.

[0056] The arrangement of the optical components is merely illustrative and is not intended to limit the scope of this invention.

[0057] Based on the same inventive concept, this invention also provides a holographic imaging method applicable to the holographic imaging system provided in the above embodiments. Figure 7 This is a flowchart illustrating a holographic imaging method provided in an embodiment of the present invention. (Refer to...) Figure 7 The holographic imaging method includes:

[0058] S110. The holographic phase structure of the holographic imaging pattern is calculated according to the Gerchberg-Saxton algorithm.

[0059] For example, in one embodiment, the result is calculated according to the GS algorithm. Figure 3 The holographic phase structure shown.

[0060] S120. The holographic phase structure is stored in a photosensitive cholesteric liquid crystal in an array arrangement to form an optical device based on a photosensitive liquid crystal superstructure.

[0061] The methods for fabricating optical devices include:

[0062] A first substrate and a second substrate are provided and disposed opposite to each other. A first alignment layer is formed on the side of the first substrate facing the second substrate, and a second alignment layer is formed on the side of the second substrate facing the first substrate. A photosensitive cholesteric liquid crystal is filled between the first substrate and the second substrate.

[0063] The first and second substrates can be flexible or rigid substrates with high light transmittance (greater than or equal to 85%). For example, the materials of the first and second substrates may include quartz glass, ITO glass, or ordinary glass, and the thickness of the substrates may be 1 mm to 2 mm. The first and second alignment layers have the same alignment direction, which is determined by the corresponding holographic phase structure.

[0064] Optionally, forming a first alignment layer on the side of the first substrate facing the second substrate and forming a second alignment layer on the side of the second substrate facing the first substrate includes:

[0065] The alignment material is spin-coated on the side of the first substrate facing the second substrate and on the side of the second substrate facing the first substrate;

[0066] Annealing is performed on a first substrate and a second substrate with spin-coated orientation material to form a first orientation layer and a second orientation layer having the same orientation direction.

[0067] For example, the spin coating process may include: first adjusting the rotation speed to 600 rpm to 900 rpm and controlling the first spin coating time to 5 s to 10 s to make the alignment material evenly distributed on the surface of the substrate to be spin coated; then adjusting the rotation speed to 2500 rpm to 3500 rpm and controlling the second spin coating time to 30 s to 50 s to make the alignment material spread.

[0068] The annealing process may include: annealing in air, annealing temperature of 80℃~120℃, and annealing time of 8min~12min.

[0069] It should be noted that the above-mentioned rotation speed and spin coating time are only illustrative examples. In other embodiments, the rotation speed and spin coating time can be adjusted according to actual needs so that the orientation film can control the orientation of cholesteric liquid crystal molecules.

[0070] S130, Multi-wavelength color hologram addressing is achieved through a color hologram optical addressing unit.

[0071] S140, Color hologram imaging is achieved through a color hologram imaging unit.

[0072] S150 achieves switching between different color hologram imaging by switching optical masks through digital micromirror devices, switching addressing light wavelengths through LED light sources, and switching multi-wavelength readout light through supercontinuous laser light sources.

[0073] Figure 8 This is a schematic diagram of the step-by-step optical addressing process provided in an embodiment of the present invention, in conjunction with reference to the reference. Figure 8 The process of step-by-step optical addressing includes:

[0074] The first step is to use optical mask 1 to achieve the first step of optical addressing.

[0075] The optical mask 1 is provided by a digital micromirror device. The optical mask 1 is placed above the photosensitive liquid crystal superstructure. External stimulus light passes through the optical mask 1 and shines onto the photosensitive liquid crystal superstructure to achieve the first step of addressing.

[0076] Optionally, under ultraviolet light irradiation, the addressing light passing through the optical mask 1 will cause the photosensitive cholesteric liquid crystal in the exposed area to adjust from the blue structural color to the green structural color; under green light irradiation, the addressing light passing through the optical mask 1 will cause the photosensitive cholesteric liquid crystal in the exposed area to adjust from the blue structural color to the green structural color.

[0077] It should be noted that, in other embodiments, the optical mask 1 described above can have its pattern switched according to actual needs, so that the area to be controlled is stimulated by light. Similarly, in other embodiments, the structural color can be adjusted by changing the light stimulation time to obtain the desired structural color.

[0078] The second step is to use optical mask 2 to achieve optical addressing in the second step.

[0079] The optical mask 2 is provided by a digital micromirror device. The optical mask 2 is placed above the photosensitive liquid crystal superstructure. External stimulus light passes through the optical mask 2 and irradiates the photosensitive liquid crystal superstructure to achieve the second step of addressing.

[0080] Optionally, under ultraviolet light irradiation, the addressing light passing through the optical mask 2 will cause the photosensitive cholesteric liquid crystal in the exposed area to adjust from a green structural color to a yellow structural color; under green light irradiation, the addressing light passing through the optical mask 2 will cause the photosensitive cholesteric liquid crystal in the exposed area to adjust from a yellow structural color to a green structural color.

[0081] It should be noted that, in other embodiments, the optical mask 2 described above can have its pattern switched according to actual needs, so that the area to be controlled is stimulated by light. Similarly, in other embodiments, the structural color can be adjusted by changing the light stimulation time to obtain the desired structural color.

[0082] The third step is to use optical mask 3 to achieve optical addressing in the third step.

[0083] The optical mask 3 is provided by a digital micromirror device. The optical mask 3 is placed above the photosensitive liquid crystal superstructure. External stimulus light passes through the optical mask 3 and shines onto the photosensitive liquid crystal superstructure to achieve the third step of addressing.

[0084] Optionally, under ultraviolet light irradiation, the addressing light passing through the optical mask 3 will cause the photosensitive cholesteric liquid crystal in the exposed area to adjust from a yellow structural color to a red structural color; under green light irradiation, the addressing light passing through the optical mask 3 will cause the photosensitive cholesteric liquid crystal in the exposed area to adjust from a red structural color to a yellow structural color.

[0085] It should be noted that, in other embodiments, the optical mask 3 described above can have its pattern switched according to actual needs, so that the area to be controlled is stimulated by light. Similarly, in other embodiments, the structural color can be adjusted by changing the light stimulation time to obtain the desired structural color.

[0086] After completing the color hologram optical addressing unit, it enters the color hologram imaging unit, for example, Figure 9 Five switchable far-field color holographic diffraction pattern images and corresponding near-field photosensitive liquid crystal structure color macroscopic photographs are provided for embodiments of the present invention. (Reference) Figure 9 Optionally, when the position coordinates (x, y) of the photosensitive liquid crystal superstructure array are (1, 3), (4, 3), and (2, 3), and are adjusted to red, green, and green structural colors respectively, a first color holographic imaging pattern can be achieved, with a corresponding near-field structural color macroscopic photograph of the photosensitive liquid crystal superstructure displayed above it; when the position coordinates (x, y) of the photosensitive liquid crystal superstructure array are (1, 3), (4, 5), and (2, 5), and are adjusted to red, green, and green structural colors respectively, a second color holographic imaging pattern can be achieved, with a corresponding near-field structural color macroscopic photograph of the photosensitive liquid crystal superstructure displayed above it; when the position coordinates (x, y) of the photosensitive liquid crystal superstructure array are (1, 3), (2, 1), (3, 1), and (4, 1), ... When the structural colors are adjusted to red, green, red, green, a third color holographic imaging pattern can be achieved, with a macroscopic image of the corresponding near-field structural color of the photosensitive liquid crystal superstructure displayed above it. When the array structure position coordinates (x, y) of the photosensitive liquid crystal superstructure are (1, 3), (2, 4), and (3, 5) and adjusted to red, orange, and orange structural colors respectively, a fourth color holographic imaging pattern can be achieved, with a macroscopic image of the corresponding near-field structural color of the photosensitive liquid crystal superstructure displayed above it. When the array structure position coordinates (x, y) of the photosensitive liquid crystal superstructure are (1, 3), (1, 5), and (5, 5) and adjusted to red, yellow, and green structural colors respectively, a fifth color holographic imaging pattern can be achieved, with a macroscopic image of the corresponding near-field structural color of the photosensitive liquid crystal superstructure displayed above it.

[0087] It should be noted that the embodiments of the present invention only exemplify the imaging of five color holographic patterns of a photosensitive liquid crystal superstructure, but are not intended to limit the color holographic pattern imaging provided by the present invention. In other embodiments, other holographic phase structures can be designed and prepared according to the actual imaging pattern requirements, and other wavelength adjustments can be made to achieve the corresponding holographic pattern imaging.

[0088] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. An optical device based on a photosensitive liquid crystal superstructure, characterized in that, For storing holographic imaging patterns, the optical device includes a first substrate, a second substrate disposed opposite to each other, and a photosensitive cholesteric liquid crystal layer located between the first substrate and the second substrate; Wherein, a first alignment layer is provided on the side of the first substrate facing the second substrate, and a second alignment layer is provided on the side of the second substrate facing the first substrate, and the first alignment layer and the second alignment layer have the same alignment direction; The first alignment layer and the second alignment layer include multiple sub-regions arranged in an array, each of which stores a holographic phase structure, so that the photosensitive cholesteric liquid crystal layer forms a photosensitive liquid crystal superstructure storing the holographic phase structure, thereby realizing the imaging of multiple color holographic patterns.

2. The optical device based on a photosensitive liquid crystal superstructure according to claim 1, characterized in that, The photosensitive cholesteric liquid crystal layer includes photosensitive chiral molecules and cholesteric liquid crystal. Under ultraviolet light stimulation, the photosensitive chiral molecules undergo a trans-cis conversion, resulting in a decrease in helical twisting force, an increase in the pitch of the cholesteric liquid crystal, and a larger central wavelength of reflected light. Under green light stimulation, the photosensitive chiral molecules undergo a cis-trans conversion, resulting in an increase in helical twisting force, a decrease in the pitch of the cholesteric liquid crystal, and a smaller central wavelength of reflected light.

3. The optical device based on a photosensitive liquid crystal superstructure according to claim 1, characterized in that, It also includes spacer particles disposed between the first substrate and the second substrate, the spacer particles being used to support the first substrate and the second substrate, forming the filling space of the photosensitive cholesteric liquid crystal layer.

4. The optical device based on a photosensitive liquid crystal superstructure according to claim 1, characterized in that, The holographic phase structure was calculated using the Gerchberg-Saxton algorithm.

5. A holographic imaging system, characterized in that, The device includes a color hologram optical addressing unit, a color hologram imaging unit, and an optical device based on a photosensitive liquid crystal superstructure as described in any one of claims 1 to 4, wherein the color hologram optical addressing unit and the color hologram imaging unit are respectively disposed on both sides of the optical device; The color hologram optical addressing unit is used to adjust the working wavelength of the region corresponding to the target color holographic imaging in the photosensitive liquid crystal superstructure of the optical device, and the color hologram imaging unit is used to realize color holographic imaging with multi-wavelength readout light.

6. The holographic imaging system according to claim 5, characterized in that, The color hologram optical addressing unit includes an LED light source, a first lens, a second lens, an aperture, and a digital micromirror device arranged sequentially along a first direction and a common optical axis; a beam splitter, a third lens, and a first receiving screen arranged sequentially along a second direction; the first direction and the second direction intersect; and the first direction and the third direction are opposite. The light beam output by the LED light source passes sequentially through the first lens, the second lens, and the aperture, and is reflected by the digital micromirror device. The reflected beam passes through the beam splitter and the third lens, and is reflected by the optical device. The reflected beam is then reflected by the beam splitter after passing through the third lens and is received by the first receiving screen.

7. The holographic imaging system according to claim 6, characterized in that, The LED light source is used to output an ultraviolet beam or a green beam. The digital micromirror device modulates the output beam of the LED light source into an array addressing beam corresponding to the array structure of the photosensitive liquid crystal superstructure, and controls the array addressing beam to independently regulate each array sub-region.

8. The holographic imaging system according to claim 7, characterized in that, The color hologram optical addressing unit uses a step-by-step addressing method to achieve color hologram addressing; The digital micromirror device is controlled to switch multiple optical masks, and the switching of multiple optical masks generates multiple array addressing lights. By switching optical masks to switch different array addressing lights in each addressing step, independent wavelength adjustment of different array sub-regions of the photosensitive liquid crystal superstructure is achieved, thereby realizing optical addressing of color holograms.

9. The holographic imaging system according to claim 5, characterized in that, The color hologram imaging unit includes a supercontinuum laser source, a polarizer, a fourth lens, a fifth lens, a sixth lens, and a second receiving screen arranged sequentially along the fourth direction, and the fourth and fifth directions intersect. The multi-wavelength readout light output from the supercontinuous laser source passes sequentially through the polarizer, the fourth lens, and the fifth lens before being incident on the optical device. After being optically addressed, the optical device reflects the light, and the reflected light passes through the sixth lens to project a color holographic image onto the second receiving screen.

10. A holographic imaging method, characterized in that, The holographic imaging method, applicable to any one of claims 5-9, comprises: The holographic phase structure of the holographic imaging pattern was calculated using the Gerchberg-Saxton algorithm. The holographic phase structure is stored in a photosensitive cholesteric liquid crystal in an array arrangement to form an optical device based on a photosensitive liquid crystal superstructure. Multi-wavelength color hologram addressing is achieved through a color hologram optical addressing unit; Color hologram imaging is achieved through a color hologram imaging unit; By switching optical masks using digital micromirror devices, switching addressing light wavelengths using LED light sources, and switching multi-wavelength readout light using supercontinuous laser light sources, the switching of different color hologram images can be achieved.

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