Optical device based on photosensitive liquid crystal superstructure, holographic imaging system and method

Abstract

The invention discloses an optical device based on a photosensitive liquid crystal superstructure and a holographic imaging system and method. The optical device is used for storing holographic imaging patterns and comprises a first substrate, a second substrate and a photosensitive cholesteric liquid crystal layer, wherein the first substrate and the second substrate are oppositely arranged, and the photosensitive cholesteric liquid crystal layer is located between the first substrate and the second substrate. Wherein one side, facing the second substrate, of the first substrate is provided with a first orientation layer, one side, facing the first substrate, of the second substrate is provided with a second orientation layer, and the first orientation layer and the second orientation layer have the same orientation direction; the first orientation layer and the second orientation layer comprise a plurality of sub-regions arranged in an array, and each sub-region stores a holographic phase structure, so that the photosensitive cholesteric liquid crystal layer forms a photosensitive liquid crystal superstructure in which the holographic phase structures are stored. The optical device provided by the invention realizes storage and reproduction of high-capacity color holographic imaging patterns by virtue of the photosensitive liquid crystal superstructure, breaks through the limitation of traditional holographic imaging, and realizes imaging of multiple color holographic patterns.

Description

Technical Field

[0001] The present invention relates to the field of liquid crystal microstructure and holographic imaging technology, and in particular to an optical device based on a photosensitive liquid crystal superstructure, a holographic imaging system and a method. Background Art

[0002] Holographic imaging technology has a wide range of applications in industrial non-destructive testing, holographic microscopy, interferometry and other fields. It not only promotes technological progress in industrial medicine and other fields, but also brings changes to human visual experience.

[0003] However, due to material and process limitations, traditional holographic imaging technology has problems such as limited information capacity, single working wavelength, and fixed holographic imaging pattern, which limits the application and development of holographic imaging. Compared with electrical addressing technology, optical addressing technology has the advantages of non-contact and strong parallel capability, but traditional optical addressing technology involves photoelectric and electro-optical conversion in applications such as optically addressed potential sensors and optically addressed spatial light modulators, which increases system complexity and reduces system flexibility. Summary of the invention

[0004] The embodiments of the present invention provide an optical device, a holographic imaging system and a method based on a photosensitive liquid crystal superstructure. The optical device relies on the photosensitive liquid crystal superstructure to achieve the storage and reproduction of large-capacity color holographic imaging patterns, breaking through the limitations of traditional holographic imaging and achieving imaging of multiple color holographic patterns.

[0005] According to one aspect of the present invention, there is provided an optical device based on a photosensitive liquid crystal superstructure for storing a holographic imaging pattern, the optical device comprising a first substrate and a second substrate arranged 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 disposed on a side of the first substrate facing the second substrate, a second alignment layer is disposed on a 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 a plurality of sub-regions arranged in an array, each of the sub-regions 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 crystals. Under the stimulation of ultraviolet light, the photosensitive chiral molecules undergo a trans-cis transformation, the helical twisting force becomes smaller, the pitch of the cholesteric liquid crystal becomes larger, and the central wavelength of the reflected light becomes larger; under the stimulation of green light, the photosensitive chiral molecules undergo a cis-trans transformation, the helical twisting force becomes larger, the pitch of the cholesteric liquid crystal becomes smaller, and the central wavelength of the reflected light becomes smaller.

[0009] Optionally, it further includes spacer particles disposed between the first substrate and the second substrate, wherein the spacer particles are used to support the first substrate and the second substrate to form a filling space for the photosensitive cholesteric liquid crystal layer.

[0010] Optionally, the holographic phase structure is calculated by a Gerchberg Saxton algorithm.

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

[0012] The color hologram light addressing unit is used to adjust the working wavelength of the area 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 by 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 in sequence along a first direction and a common optical axis, a beam splitter and a third lens arranged in sequence along a second direction, and a first receiving screen arranged along a third direction, the first direction intersects with the second direction, and the first direction is opposite to the third direction;

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

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

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

[0017] The digital micromirror device is controlled to switch a plurality of optical masks, and the plurality of optical masks are switched to generate a plurality of array addressing lights. Different array addressing lights are switched in each addressing process by switching the optical masks, so as to achieve independent wavelength adjustment of different array sub-areas of the photosensitive liquid crystal superstructure and realize color hologram optical addressing.

[0018] Optionally, the color hologram imaging unit includes a supercontinuum laser light source, a polarizer, a fourth lens, a fifth lens arranged in sequence along a fourth direction, and a sixth lens and a second receiving screen arranged along a fifth direction, and the fourth direction intersects with the fifth direction;

[0019] The multi-wavelength readout light output by the supercontinuum laser light source passes through the polarizer, the fourth lens and the fifth lens in sequence and is incident on the optical device. After optical addressing, the optical device reflects the reflected light, and the reflected light passes through the sixth lens to project the color holographic image onto the second receiving screen.

[0020] According to another aspect of the present invention, a holographic imaging method is provided, which is applicable to the above-mentioned holographic imaging system, and the holographic imaging method comprises:

[0021] The holographic phase structure of the holographic imaging pattern is calculated according to 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 by a color hologram imaging unit;

[0025] By switching the optical mask through a digital micromirror device, switching the addressing light wavelength through an LED light source, and switching the multi-wavelength readout light through a supercontinuum laser light source, switching of different color hologram imaging is achieved.

[0026] The optical device based on the photosensitive liquid crystal superstructure provided by the embodiment of the present 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 substrate and the second substrate; wherein a first orientation layer is provided on the side of the first substrate facing the second substrate, and a second orientation layer is provided on the side of the second substrate facing the first substrate, and the first orientation layer and the second orientation layer have the same orientation direction; the first orientation layer and the second orientation layer include a plurality of sub-regions arranged in an array, each sub-region stores a holographic phase structure, so that the photosensitive cholesteric liquid crystal layer forms a photosensitive liquid crystal superstructure storing a holographic phase structure. The technical solution of the embodiment of the present invention utilizes the light stimulation response characteristics of the photosensitive cholesteric liquid crystal, and its Bragg reflection band undergoes red / blue shift under light stimulation, which can cover an ultra-wide band from visible to near-infrared, laying a foundation for dynamic light field control; and the Bragg reflection light of the photosensitive cholesteric liquid crystal carries geometric phase information, which provides a new platform for the development of pure phase holographic imaging. Photosensitive materials can be stimulated by light and can also regulate holographic light fields. They are expected to provide new ideas and methods for the development of all-light regulation, realize the storage and reproduction of large-capacity color holographic imaging patterns, break through the limitations of traditional holographic imaging, and realize the imaging of multiple color holographic patterns.

[0027] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

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

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

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

[0032] Figure 4 A characterization diagram of the light stimulus response spectrum of the right-handed photosensitive cholesteric liquid crystal provided in an embodiment of the present invention;

[0033] Figure 5A microscopic photograph of the light-stimulation response of the photosensitive cholesteric liquid crystal provided by an embodiment of the present invention and a macroscopic photograph of the photosensitive cholesteric liquid crystal after local independent addressing light stimulation;

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

[0035] Figure 7 A schematic diagram of a flow chart of a holographic imaging method provided by an embodiment of the present invention;

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

[0037] Fig. 9 Five switchable far-field color holographic diffraction spot images and corresponding near-field photosensitive liquid crystal structural color macroscopic photos are provided in the embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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 and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0040] Figure 1 A schematic diagram of an optical device structure based on a photosensitive liquid crystal superstructure provided by an embodiment of the present invention is used to store holographic imaging patterns, referring to Figure 1The optical device includes a first substrate 10 and a second substrate 20 that are arranged opposite to each other, and a photosensitive cholesteric liquid crystal layer 30 located between the first substrate 10 and the second substrate 20; wherein a first orientation layer 40 is provided on the side of the first substrate 10 facing the second substrate 20, and a second orientation layer 50 is provided on the side of the second substrate 20 facing the first substrate 10, and the first orientation layer 40 and the second orientation layer 50 have the same orientation direction; the first orientation layer 40 and the second orientation layer 50 include a plurality of sub-regions arranged in an array, each sub-region stores a holographic phase structure, so that the photosensitive cholesteric liquid crystal layer 30 forms a photosensitive liquid crystal superstructure storing a holographic phase structure. Exemplarily, taking the first orientation layer 40 and the second orientation layer 50 including 25 sub-regions arranged in a 5×5 array structure as an example, Figure 2 A schematic top view of an optical device provided by an embodiment of the present invention schematically shows the arrangement of surface liquid crystal molecules of 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 holographic phase structure. The arrangement of surface liquid crystal molecules of the photosensitive cholesteric liquid crystal is determined by the first orientation layer 40 and the second orientation layer 50. As shown in the top view, it is a 5×5 array structure arrangement. The arrangement of surface liquid crystal molecules of each array sub-region represents a holographic phase structure. It can be understood that Figure 2 The arrangement of the surface liquid crystal molecules of the photosensitive cholesteric liquid crystal is only exemplified, rather than the actual size and arrangement.

[0041] Optionally, the photosensitive cholesteric liquid crystal layer includes photosensitive chiral molecules and cholesteric liquid crystals. Under ultraviolet light stimulation, the photosensitive chiral molecules undergo a trans-cis transformation, the helical twisting force decreases, the helical pitch of the cholesteric liquid crystal increases, and the central wavelength of the reflected light increases; under green light stimulation, the photosensitive chiral molecules undergo a cis-trans transformation, the helical twisting force increases, the helical pitch of the cholesteric liquid crystal decreases, and the central wavelength of the reflected light decreases. Figure 1 As shown, the photosensitive liquid crystal superstructure presents four different pitch arrangements at different locations.

[0042] Optionally, the holographic phase structure is calculated by a Gerchberg Saxton algorithm.

[0043] The Gerchberg Saxton (GS) algorithm is an iterative algorithm for reconstructing missing phase information, which is widely used in optical imaging, digital holography, signal processing and other fields. The algorithm gradually optimizes the reconstructed object phase by alternately propagating information between the object plane and the image plane, thereby restoring the missing phase information. Figure 3 A schematic diagram of a holographic phase structure corresponding to a target holographic imaging pattern provided by an embodiment of the present invention. Figure 3In one embodiment of the present invention, the holographic imaging patterns are five patterns of humans at different growth stages, five patterns of trees at different growth stages, and one pattern of the sun, and the corresponding holographic phase structures are obtained by the GS algorithm. It should be noted that the above holographic phase structure, in other implementations, can be designed and switched according to actual needs to achieve the desired target pattern imaging.

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

[0045] Understandably, Figure 1 The spacer particles 60 are used to support the positional relationship of the first substrate 10 and the second substrate 20, but not the actual size and proportion. Optionally, the spacer particles 60 include quartz balls or quartz columns, which can be designed according to actual conditions during implementation. Optionally, along the direction perpendicular to the plane where the first substrate 10 is located, 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 crystal has light stimulus response characteristics, for example, Figure 4 This is a characterization of the light stimulus response spectrum of the right-handed photosensitive cholesteric liquid crystal provided by the embodiment of the present invention. Figure 4 Optionally, when the incident light is linearly polarized light, the Bragg reflection band of the right-handed photosensitive cholesteric liquid crystal will red-shift under ultraviolet light stimulation, and different stimulation times will bring about different degrees of red-shift of the Bragg reflection band. 2 Under the stimulation of ultraviolet light, the stimulation time can cover the visible to near-infrared band (400nm~2000nm) within 0~52s; 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 phase liquid crystal can achieve extremely high reflection and cover the visible band (400nm~800nm) within 13s.

[0047] It should be noted that the embodiment of the present invention only exemplarily shows the light stimulus response spectrum characterization diagram of right-handed photosensitive cholesteric liquid crystal, but it is not a limitation of the photosensitive cholesteric liquid crystal provided by the present invention. In other embodiments, according to actual needs, photosensitive cholesteric liquid crystals with other light stimulus response properties are prepared, and the Bragg reflection band can be adjusted accordingly.

[0048] For example, Figure 5The photosensitive cholesteric liquid crystal provided in the embodiment of the present invention has a light stimulus response microphotograph and a macrophotograph of the photosensitive cholesteric liquid crystal after local independent addressing light stimulus. Figure 5 The photosensitive cholesteric liquid crystal can present different colors of structural colors under light stimulation at different times, and can adjust the structural color back and forth in the visible light range under ultraviolet / green light addressing light stimulation. In particular, after addressing light stimulation, different regions of the photosensitive cholesteric liquid crystal are stimulated at different times, thereby presenting different structural colors. Optionally, different regions of the photosensitive cholesteric liquid crystal are combined into a colorful English letter Growth pattern after local independent addressing light stimulation.

[0049] It should be noted that the embodiment of the present invention only exemplarily shows a schematic diagram of a macroscopic photograph of the photosensitive cholesteric liquid crystal after local independent addressing light stimulation, but is not a limitation of the array addressing light provided by the present invention. In other embodiments, other addressing lights are prepared according to actual needs, and corresponding adjustments can be made to the photosensitive cholesteric liquid crystal, including but not limited to the Growth pattern.

[0050] The technical solution of the embodiment of the present invention utilizes the light stimulation response characteristics of photosensitive cholesteric liquid crystals. Its Bragg reflection band undergoes red / blue shift under light stimulation, which can cover an ultra-wide band from visible to near-infrared, laying the foundation for dynamic light field control; and the Bragg reflection light of photosensitive cholesteric liquid crystals carries geometric phase information, which provides a new platform for the development of pure phase holographic imaging. Photosensitive materials can be stimulated by light and can also control holographic light fields, which is expected to provide new ideas and methods for the development of all-optical control, realize the storage and reproduction of large-capacity color holographic imaging patterns, break through the limitations of traditional holographic imaging, and realize the imaging of multiple color holographic patterns.

[0051] Based on the optical device provided in the above embodiment, the embodiment of the present invention further provides a holographic imaging system. Figure 6 A schematic diagram of a holographic imaging system according to an embodiment of the present invention is provided. 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, wherein the color hologram optical addressing unit 100 and the color hologram imaging unit 200 are respectively arranged on both sides of the optical device 300; the color hologram optical addressing unit 100 is used to adjust the working wavelength of the area 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 by 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 in sequence along a first direction (positive direction of the y-axis) along a common optical axis, a beam splitter 106 and a third lens 107 arranged in sequence along a second direction (negative direction of the z-axis), and a first receiving screen 108 arranged along a third direction (negative direction of the y-axis), 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 101 passes through the first lens 102, the second lens 103, and the aperture 104 in sequence, and is then reflected by the digital micromirror device 105, the reflected light beam of 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 of the optical device 300 passes through the third lens 107, is reflected by the beam splitter 106, and is then received by the first receiving screen 108.

[0053] Wherein, the LED light source is an ultraviolet / green light LED, which is used to emit ultraviolet light or green light, such as 365nm ultraviolet light or 532nm green light. The digital micromirror device 105 modulates the output light beam of the LED light source 101 into an array addressing light corresponding to the array structure of the photosensitive liquid crystal superstructure, controls the array addressing light to independently adjust each array sub-region, and controls the light intensity of the addressing light array sub-region to be 0 or 1; wherein, 1 indicates that the micromirror in the digital micromirror device 105 reflects the addressing light to the optical device, and 0 indicates that the addressing light is reflected outside the optical device, and the array addressing light adjusts the working wavelength of the area corresponding to the target color holographic imaging in the photosensitive liquid crystal superstructure. The array addressing light is obtained by passing through the first lens 102, the second lens 103, and the aperture 104 in sequence according to the light beam output by the LED light source, and then being reflected by the digital micromirror device 105. The array addressing light passes through the beam splitter 106 and the third lens 107 and then irradiates the photosensitive liquid crystal superstructure. According to the light stimulus response characteristics of the photosensitive cholesteric liquid crystal in the optical device 300, the ultraviolet / green light array addressing light is used to adjust the photosensitive liquid crystal superstructure to different array sub-positions and different working wavelengths. Optionally, the color hologram light addressing unit 100 adopts a step-by-step addressing method to achieve color holographic addressing; the digital micromirror device 105 is controlled to switch multiple optical masks, such as optical masks 1, 2...n, and multiple optical masks are switched to generate multiple array addressing lights 1, 2...n, and different array addressing lights are switched in each step of the addressing process by switching the optical masks, so as to achieve independent wavelength adjustment of different array sub-regions of the photosensitive liquid crystal superstructure, and achieve color hologram light addressing.

[0054] Optionally, the color hologram imaging unit 200 includes a supercontinuum laser light source 201, a polarizer 202, a fourth lens 203, a fifth lens 204 arranged in sequence along a fourth direction (z-axis angle -10° direction), and a sixth lens 205 and a second receiving screen 206 arranged in a fifth direction (z-axis angle +10° direction), and the fourth direction and the fifth direction intersect; the multi-wavelength readout light output by the supercontinuum laser light source 201 passes through the polarizer 202, the fourth lens 203 and the fifth lens 204 in sequence and then is incident on the optical device 300, and is reflected by the optical device 300 after optical addressing, and the reflected light passes through the sixth lens 205 to project the color holographic image onto the second receiving screen 206.

[0055] The supercontinuum laser light source 201 is used to output supercontinuum laser light covering the visible light band and the near infrared band.

[0056] The arrangement of the optical devices is merely illustrative and is not a limitation of the embodiments of the present invention.

[0057] Based on the same inventive concept, an embodiment of the present invention further provides a holographic imaging method, which is applicable to the holographic imaging system provided in the above embodiment. Figure 7 A schematic diagram of a holographic imaging method provided by an embodiment of the present invention, referring to Figure 7 , the holographic imaging method comprises:

[0058] S110. Calculate the holographic phase structure of the holographic imaging pattern according to the Gerchberg Saxton algorithm.

[0059] Exemplarily, in one embodiment, according to the GS algorithm, Figure 3 The holographic phase structure shown.

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

[0061] The method for preparing the optical device includes:

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

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

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

[0065] Spin coating the alignment material on the side of the first substrate facing the second substrate and the side of the second substrate facing the first substrate;

[0066] The first substrate and the second substrate on which the alignment material is spin-coated are annealed to form a first alignment layer and a second alignment layer having the same alignment direction.

[0067] Exemplarily, the spin coating process may include: first adjusting the rotation speed to 600 rpm to 900 rpm, controlling the first spin coating time to 5s to 10s, so that the orientation material is evenly distributed on the surface of the spin-coated substrate; then adjusting the rotation speed to 2500 rpm to 3500 rpm, controlling the second spin coating time to 30s to 50s, so that the orientation material is spread.

[0068] The annealing process may include: annealing atmosphere is air, annealing temperature is 80° C. to 120° C., and annealing time is 8 min to 12 min.

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

[0070] S130, realizing multi-wavelength color hologram addressing through a color hologram optical addressing unit.

[0071] S140, realizing color hologram imaging through a color hologram imaging unit.

[0072] S150, by switching the optical mask through the digital micromirror device, switching the addressing light wavelength through the LED light source, and switching the multi-wavelength readout light through the supercontinuum laser light source, the switching of different color hologram imaging is realized.

[0073] Figure 8 A schematic diagram of the process of step-by-step optical addressing provided by an embodiment of the present invention, combined with reference to Figure 8 , the process of step-by-step optical addressing includes:

[0074] In the first step, optical mask 1 is used to implement the first optical addressing.

[0075] Among them, the optical mask 1 is provided by a digital micromirror device, and the optical mask 1 is placed above the photosensitive liquid crystal superstructure. The external stimulation light is irradiated onto the photosensitive liquid crystal superstructure through the optical mask 1 to realize 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 exposure area to be adjusted from a blue structural color to a 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 exposure area to be adjusted from a blue structural color to a green structural color.

[0077] It should be noted that, in other embodiments, the optical mask 1 can switch the mask pattern according to actual needs so that the area to be regulated is stimulated by light. In other embodiments, the adjustment of the structural color can adjust the light stimulation time according to needs to obtain the required structural color.

[0078] In the second step, optical mask 2 is used to implement the second step of optical addressing.

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

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

[0081] It should be noted that, in other embodiments, the optical mask 2 can switch the mask pattern according to actual needs so that the area to be regulated can be stimulated by light. In other embodiments, the adjustment of the structural color can adjust the light stimulation time according to needs to obtain the required structural color.

[0082] The third step is to use the optical mask 3 to implement the third step of optical addressing.

[0083] The optical mask 3 is provided by a digital micromirror device, and is placed above the photosensitive liquid crystal superstructure. External stimulation light is irradiated onto the photosensitive liquid crystal superstructure through the optical mask 3 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 exposure area to be adjusted 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 exposure area to be adjusted from a red structural color to a yellow structural color.

[0085] It should be noted that, in other embodiments, the optical mask 3 can switch the mask pattern according to actual needs so that the area to be regulated is stimulated by light. In other embodiments, the adjustment of the structural color can adjust the light stimulation time according to needs to obtain the required structural color.

[0086] After the color hologram optical addressing unit is completed, the color hologram imaging unit is entered. For example, Fig. 9 Five switchable far-field color holographic diffraction spot images and corresponding near-field photosensitive liquid crystal structural color macroscopic photos provided by the embodiment of the present invention. Fig. 9 Optionally, when the array structure position coordinates (x, y) of the light-stimulated photosensitive liquid crystal superstructure are (1, 3), (4, 3), (2, 3), and are adjusted to red, green, and green structural colors respectively, a first color holographic imaging pattern can be realized, and a macroscopic photograph of the near-field structural color of the corresponding photosensitive liquid crystal superstructure is displayed above it; when the array structure position coordinates (x, y) of the light-stimulated photosensitive liquid crystal superstructure 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 realized, and a macroscopic photograph of the near-field structural color of the corresponding photosensitive liquid crystal superstructure is displayed above it; when the array structure position coordinates (x, y) of the light-stimulated photosensitive liquid crystal superstructure are (1, 3), (2, 1), (3, 1), and (4, 1), respectively When adjusted to red, green, red, and green structural colors, the third color holographic imaging pattern can be realized, and the corresponding near-field structural color macroscopic photograph of the photosensitive liquid crystal superstructure is displayed above it; when the array structure position coordinates (x, y) of the light-stimulated photosensitive liquid crystal superstructure are (1, 3), (2, 4), and (3, 5), respectively adjusted to red, orange, and orange structural colors, the fourth color holographic imaging pattern can be realized, and the corresponding near-field structural color macroscopic photograph of the photosensitive liquid crystal superstructure is displayed above it; when the array structure position coordinates (x, y) of the light-stimulated photosensitive liquid crystal superstructure are (1, 3), (1, 5), and (5, 5), respectively adjusted to red, yellow, and green structural colors, the fifth color holographic imaging pattern can be realized, and the corresponding near-field structural color macroscopic photograph of the photosensitive liquid crystal superstructure is displayed above it.

[0087] It should be noted that the embodiment of the present invention only exemplarily shows five color holographic pattern imaging of a photosensitive liquid crystal superstructure, but it is not a limitation of the color holographic pattern imaging provided by the present invention. In other embodiments, according to the actual imaging pattern requirements, other holographic phase structures are designed and prepared, and other wavelength adjustments are performed to achieve corresponding holographic pattern imaging.

[0088] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An optical device based on a photosensitive liquid crystal superstructure, characterized in that: Used to store holographic imaging patterns, the optical device comprises a first substrate and a second substrate arranged 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 disposed on a side of the first substrate facing the second substrate, a second alignment layer is disposed on a 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 a plurality of sub-regions arranged in an array, each of the sub-regions stores a holographic phase structure, so that the photosensitive cholesteric liquid crystal layer forms a photosensitive liquid crystal superstructure storing a holographic phase structure.

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

3. The optical device based on the 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, and the spacer particles are used to support the first substrate and the second substrate to form a filling space for the photosensitive cholesteric liquid crystal layer.

4. The optical device based on the photosensitive liquid crystal superstructure according to claim 1, characterized in that: The holographic phase structure is calculated by the Gerchberg Saxton algorithm.

5. A holographic imaging system, characterized in that: It comprises a color hologram light addressing unit, a color hologram imaging unit and an optical device based on a photosensitive liquid crystal superstructure according to any one of claims 1 to 4, wherein the color hologram light addressing unit and the color hologram imaging unit are respectively arranged on two sides of the optical device; The color hologram light addressing unit is used to adjust the working wavelength of the area 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 by multi-wavelength readout light.

6. The holographic imaging system according to claim 5, characterized in that: The color hologram optical addressing unit comprises an LED light source, a first lens, a second lens, an aperture and a digital micromirror device arranged in sequence along a first direction with a common optical axis, a beam splitter and a third lens arranged in sequence along a second direction, and a first receiving screen arranged along a third direction, wherein the first direction intersects with the second direction, and the first direction is opposite to the third direction; The light beam output by the LED light source passes through the first lens, the second lens, and the aperture in sequence, and is then reflected by the digital micromirror device. The reflected light beam passes through the beam splitter and the third lens and is then reflected by the optical device. The reflected light beam passes through the third lens and is reflected by the beam splitter and is then 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 light beam or a green light beam. The digital micromirror device modulates the output light beam of the LED light source into an array addressing light corresponding to the array structure of the photosensitive liquid crystal superstructure, and controls the array addressing light to independently regulate each array sub-area.

8. The holographic imaging system according to claim 7, characterized in that: The color hologram optical addressing unit adopts a step-by-step addressing method to achieve color holographic addressing; The digital micromirror device is controlled to switch a plurality of optical masks, and the plurality of optical masks are switched to generate a plurality of array addressing lights. Different array addressing lights are switched in each addressing process by switching the optical masks, so as to achieve independent wavelength adjustment of different array sub-areas of the photosensitive liquid crystal superstructure and realize color hologram optical addressing.

9. The holographic imaging system according to claim 5, characterized in that: The color hologram imaging unit comprises a supercontinuum laser light source, a polarizer, a fourth lens, a fifth lens arranged in sequence along a fourth direction, and a sixth lens and a second receiving screen arranged along a fifth direction, wherein the fourth direction intersects with the fifth direction; The multi-wavelength readout light output by the supercontinuum laser light source passes through the polarizer, the fourth lens and the fifth lens in sequence and is incident on the optical device. After optical addressing, the optical device reflects the reflected light, and the reflected light passes through the sixth lens to project the color holographic image onto the second receiving screen.

10. A holographic imaging method, characterized in that: Applicable to the holographic imaging system according to any one of claims 5 to 9, the holographic imaging method comprising: The holographic phase structure of the holographic imaging pattern is calculated according to 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 by a color hologram imaging unit; By switching the optical mask through a digital micromirror device, switching the addressing light wavelength through an LED light source, and switching the multi-wavelength readout light through a supercontinuum laser light source, switching of different color hologram imaging is achieved.

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