A preparation device for a liquid crystal lens and a preparation method for a liquid crystal lens

Abstract

The present application provides a preparation device and a preparation method of a liquid crystal lens, the preparation device includes a light source component and a geometric phase liquid crystal lens component arranged along an optical path; the geometric phase liquid crystal lens component includes two geometric phase liquid crystal lenses with different focal lengths; one geometric phase liquid crystal lens converts the linear polarized light emitted by the light source component into two circularly polarized lights with different rotation directions; the other geometric phase liquid crystal lens reverses the rotation directions of the two circularly polarized lights; the two circularly polarized lights are a spherical wave and a plane wave, respectively, and the two circularly polarized lights interfere to form linear polarized light; the light field formed by the linear polarized light changes periodically, and the period is a changing period. The linear polarized light with periodic changes in polarization state is formed by the geometric phase liquid crystal lens, and the period of the linear polarized light is a changing period. Thus, a periodic change can be formed in the direction of the orientation layer orientation, and the periodic change, the entire exposure optical path is simple and reliable, easy to adjust, convenient and flexible.

Description

Technical Field

[0001] The present application relates to the field of near-eye display technology, and in particular to a device for preparing a liquid crystal lens and a method for preparing a liquid crystal lens. Background Art

[0002] Geometric phase liquid crystal lenses are widely used in near-eye display devices. Their main role in near-eye display devices is to improve the immersion and comfort of near-eye display devices and optimize the optical performance of near-eye display devices.

[0003] When preparing geometric phase liquid crystal lenses, commonly used exposure methods include polarization holography, laser direct writing, and digital micromirror device (DMD) dynamic projection technology. For example, the DMD dynamic projection method uses a precise electrically controlled optical path to achieve exposure, but it requires multiple exposures and has high requirements for mechanical control accuracy, resulting in high preparation costs. Summary of the invention

[0004] The present application provides a device for preparing a liquid crystal lens and a method for preparing a liquid crystal lens, which simplify the exposure light path of the liquid crystal lens.

[0005] The present application provides a device for preparing a liquid crystal lens, which comprises a light source component and a geometric phase liquid crystal lens component arranged along an optical path; wherein:

[0006] The light source assembly is used to emit linearly polarized light;

[0007] The geometric phase liquid crystal lens assembly includes a first geometric phase liquid crystal lens and a second geometric phase liquid crystal lens with different focal lengths;

[0008] The first geometric phase liquid crystal lens is used to convert the linear polarized light into a first left-handed circularly polarized light and a first right-handed circularly polarized light; wherein the first left-handed circularly polarized light is a converging spherical wave, and the first right-handed circularly polarized light is a diverging spherical wave;

[0009] The second geometric phase liquid crystal lens is used to convert the first left-handed circularly polarized light into a second right-handed circularly polarized light, and to convert the first right-handed circularly polarized light into a second left-handed circularly polarized light; wherein the second left-handed circularly polarized light interferes with the second right-handed circularly polarized light to form a linear polarized light that illuminates the orientation layer; the light field formed by the linear polarized light changes periodically, and the period is a changing period; wherein the second left-handed circularly polarized light is a divergent spherical wave, and the second right-handed circularly polarized light is a plane wave.

[0010] In the above technical solution, by using the cooperation of the first geometric phase liquid crystal lens and the second geometric phase liquid crystal lens, a linear polarized light with periodic polarization state changes is formed, and the period of the linear polarized light is a change period. Therefore, when it is irradiated on the orientation layer for orientation, the orientation direction can be formed to change periodically, and the periodic change. The entire exposure light path is simple and reliable, easy to adjust, convenient and flexible.

[0011] In a specific possible implementation scheme, the light field satisfies:

[0012] Along the direction from the center of the light field to the edge of the light field, the period of the light field gradually decreases.

[0013] In a specific implementation manner, the second left-handed circularly polarized light interferes with the second right-handed circularly polarized light to form linearly polarized light; along the X direction, the period of the linearly polarized light satisfies:

[0014] ;

[0015] Wherein, θ is the angle between the second left-handed circularly polarized light and the second right-handed circularly polarized light; α is the linear polarization direction; λ0 is the wavelength of the linearly polarized light, is the period of the linear polarized light; x is the plane coordinate of the position where the linear polarized light irradiates;

[0016] In a specific embodiment, the polarization direction of the linearly polarized light satisfies:

[0017] ;

[0018] ;

[0019] Wherein, f′ is the focal length of the geometric phase liquid crystal lens assembly; π is the circumference of a circle; x and y are the plane coordinates of the position of the alignment layer irradiated by the linearly polarized light; and λ0 is the wavelength of the linearly polarized light.

[0020] In a specific embodiment, the geometric phase liquid crystal lens component satisfies:

[0021] ;

[0022] d=f2-f1;

[0023] Wherein, f′ is the focal length of the liquid crystal lens assembly, f1 is the focal length of the first geometric phase liquid crystal lens, f2 is the focal length of the second geometric phase liquid crystal lens, and d is the distance between the first geometric phase liquid crystal lens and the second geometric phase liquid crystal lens.

[0024] In a specific embodiment, the light source assembly includes a laser, a beam expander lens, a collimator lens, and a polarizer arranged along the optical path.

[0025] In a second aspect, a method for preparing a liquid crystal lens is also provided, the method comprising the following steps:

[0026] Spin coating an alignment material on a substrate to form an alignment layer on the substrate;

[0027] The liquid crystal lens manufacturing device described in any one of the above items is used to irradiate the alignment layer to perform exposure alignment.

[0028] In the above technical solution, by using the cooperation of the first geometric phase liquid crystal lens and the second geometric phase liquid crystal lens, a linear polarized light with periodic polarization state changes is formed, and the period of the linear polarized light is a change period. Therefore, when it is irradiated on the orientation layer for orientation, the orientation direction can be formed to change periodically, and the periodic change. The entire exposure light path is simple and reliable, easy to adjust, convenient and flexible.

[0029] In a specific embodiment, the method further comprises:

[0030] Before spin coating the alignment material on the substrate, a transparent conductive layer is prepared on the substrate, and the two substrates are aligned to form a liquid crystal cell for containing liquid crystals;

[0031] After the alignment layer is exposed, liquid crystal material is poured into the liquid crystal cell.

[0032] In a specific embodiment, the method further comprises: coating a liquid crystal material on the substrate after exposing the alignment layer.

[0033] In a specific embodiment, it also includes:

[0034] Use substrate cleaning agent, anhydrous ethanol, and deionized ultrasonic cleaning of the substrate;

[0035] The substrate is dried in an oven, and cleaned with an ultraviolet sampling processor to remove organic particles remaining on the substrate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of the arrangement of the liquid crystal layer of the geometric phase liquid crystal lens provided in an embodiment of the present application;

[0037] Figure 2 A phase diagram of a liquid crystal layer of a geometric phase liquid crystal lens provided in an embodiment of the present application;

[0038] Figure 3 A schematic diagram of a device for preparing a geometric phase liquid crystal lens provided in an embodiment of the present application;

[0039] Figure 4~Figure 6 Schematic diagram of the change of polarization state of different polarized lights passing through the geometric phase liquid crystal lens;

[0040] Figure 7 and Figure 8 A schematic diagram of the change in polarization state of linearly polarized light after passing through a geometric phase liquid crystal lens group provided in an embodiment of the present application;

[0041] Fig. 9 A schematic diagram of the electric field vector of the second left-handed circularly polarized light and the second right-handed circularly polarized light provided in an embodiment of the present application;

[0042] Fig.10 A schematic diagram of interference between a second left-handed circularly polarized light and a second right-handed circularly polarized light provided in an embodiment of the present application;

[0043] Fig.11 A flow chart of a method for preparing a liquid crystal lens provided in an embodiment of the present application;

[0044] Fig.12 A schematic diagram of the structure of an active geometric phase liquid crystal lens provided in an embodiment of the present application;

[0045] Fig.13 A schematic structural diagram of a passive geometric phase liquid crystal lens provided in an embodiment of the present application. DETAILED DESCRIPTION

[0046] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings.

[0047] It should be noted that, unless otherwise defined, the technical terms or scientific terms used in one or more embodiments of this specification should be understood by people with ordinary skills in the field to which this disclosure belongs. The "first", "second" and similar words used in one or more embodiments of this specification do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word cover the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0048] To facilitate understanding, several terms involved in the embodiments of the present application are first introduced.

[0049] Linearly polarized light, also known as Linearly polarized light, abbreviated as LP, is a light vector that vibrates only in a fixed direction in the direction of light propagation.

[0050] Left-handed circularly polarized light, in English Left Cricular Polarized, abbreviated as LCP, the electric vector magnitude of left-handed circularly polarized light remains unchanged, but the direction changes with time, and the phase difference is φ=(2m+1 / 2)π.

[0051] Right-handed circularly polarized light, in English Right Cricular Polarized, referred to as RCP, the electric vector magnitude of right-handed circularly polarized light remains unchanged, but the direction changes with time, and the phase difference is φ = (2m-1 / 2) π.

[0052] To facilitate understanding of the liquid crystal lens manufacturing device provided in the embodiment of the present application, its application scenario is first described. The liquid crystal lens manufacturing device provided in the embodiment of the present application is used to manufacture a liquid crystal lens, which is used in manufacturing a near-eye display device.

[0053] Liquid crystal lens is a special plane diffraction optical element - geometric phase (Pancharatnam Berryphase, PB) lens. Unlike traditional optical elements, it does not rely on optical path difference (refractive index difference or thickness difference) to obtain phase distribution, but achieves phase modulation by changing the liquid crystal director in space. Figure 1 The typical PB liquid crystal lens shown in FIG. 1 , in which the liquid crystal director is radially distributed, Figure 1 The X-axis and the Y-axis are two mutually perpendicular directions on the plane where the liquid crystal layer is located. Figure 1 The corresponding phase change of the liquid crystal in the parabolic distribution is as follows: Figure 2 As shown in . Among them, Figure 2 LCP is left-handed circularly polarized light, and RCP is right-handed circularly polarized light. During its preparation process, through the photo-alignment technology, pattern exposure is adopted to make the alignment agent molecules (components of the alignment layer) in different regions regularly distributed along different directions, and the liquid crystal molecules are arranged in an orderly manner under the action of the alignment layer, thereby realizing the function of the lens.

[0054] When using the polarization holography method, laser direct writing method and digital micromirror device (DMD) dynamic projection technology in the prior art, there are different problems such as the influence of the preparation aperture and deflection angle, too high control accuracy requirements and weak anti-interference ability, or multiple exposures are required. To this end, the embodiment of the present application provides a preparation device for a liquid crystal lens to improve the preparation effect of the liquid crystal lens.

[0055] refer to Figure 3 , Figure 3 The schematic diagram of the preparation device of the liquid crystal lens provided in the embodiment of the present application is shown. The main structure of the preparation device of the liquid crystal lens provided in the embodiment of the present application includes a light source component 10 and a geometric phase liquid crystal lens group 20. Among them, the light source component 10 and the geometric phase liquid crystal lens group 20 are arranged along the light path, the light source component 10 emits linearly polarized light, and the geometric phase liquid crystal lens group 20 is used to process the linearly polarized light emitted by the light source component 10 to obtain a light field for irradiating the orientation layer 30 of the liquid crystal lens, the light field is a light field composed of linearly polarized light, and the light field formed by the linearly polarized light changes periodically, and the period is a period of change. The periodic change of the period of the above-mentioned light field refers to the periodic change of the polarization direction of the linear polarization in the light field. The orientation layer 30 of the geometric phase liquid crystal lens is oriented by irradiation of the light field. As Figure 3 As shown in FIG. 1 , the alignment layer 30 is carried on a substrate and placed in an optical path, and the light field emitted by the geometric phase liquid crystal lens group 20 irradiates the alignment layer 30. The structures of various parts of the liquid crystal lens manufacturing device are described in detail below in conjunction with specific drawings.

[0056] Continue to refer Figure 3 , the light source assembly 10 is used to provide linearly polarized light in the embodiment of the present application, and its specific composition can be composed of different components. In one example, the light source assembly 10 may include a laser 11, a beam expander lens 12, a collimator lens 13 and a polarizer 14 arranged along the optical path. The laser emitted by the laser 11 can be expanded by the beam expander lens 12, and then collimated and adjusted by the collimator lens 13, and finally polarized by the polarizer 14 to form linear polarized light. Of course, in other examples, the beam expander lens 12 and the collimator lens 13 can be selected as needed. Or other methods can be used to form linearly polarized light. The light source assembly 10 provided in the embodiment of the present application is not limited to Figure 1 The specific structure exemplified in .

[0057] Continue to refer Figure 1 The geometric phase liquid crystal lens set 20 provided in the embodiment of the present application includes two geometric phase liquid crystal lenses, which are named as the first geometric phase liquid crystal lens 21 and the second geometric phase liquid crystal lens 22 for the convenience of description, and the focal lengths of the first geometric phase liquid crystal lens 21 and the second geometric phase liquid crystal lens 22 are different. Among them, the focal length of the first geometric phase liquid crystal lens 21 is f1, and the focal length of the second geometric phase liquid crystal lens 22 is f2. When arranged along the optical path, the first geometric phase liquid crystal lens 21 is close to the light source assembly 10, and the second geometric phase liquid crystal lens 22 is close to the orientation layer 30. The linearly polarized light emitted by the light source assembly 10 first passes through the first fiber liquid crystal lens, and then passes through the second geometric phase liquid crystal lens 22.

[0058] For easier understanding, let's first introduce the liquid crystal lens, which can adjust the polarization state of the incident light and change the focal length of the outgoing light. Figure 4~Figure 6 , Figure 4~Figure 6 FIG. 1 shows the change in polarization state of light of different polarization states when passing through the geometric phase liquid crystal lens 100. Figure 4 As shown in , when linearly polarized light enters the straight geometric phase liquid crystal lens 100, two beams of left-handed circularly polarized light with a focal length of +f and right-handed circularly polarized light with a focal length of -f are emitted; Figure 5 As shown, when left-handed circularly polarized light is irradiated onto the geometric phase liquid crystal lens 100, the surface of the geometric phase liquid crystal lens 100 is a lens with a focal length of -f. Therefore, after the left-handed circularly polarized light is incident onto the geometric phase liquid crystal lens 100, it is emitted as right-handed circularly polarized light with a focal length of -f; Figure 6 As shown, when right-handed circularly polarized light is irradiated onto the geometric phase liquid crystal lens 100, the surface of the geometric phase liquid crystal lens 100 is a lens with a focal length of +f. Therefore, after the right-handed circularly polarized light enters the geometric phase liquid crystal lens 100, it is emitted as left-handed circularly polarized light with a focal length of +f.

[0059] Therefore, when the linear polarized light is irradiated to the first geometric phase liquid crystal lens 21, the first geometric phase liquid crystal lens 21 converts the linear polarized light into the first left-handed circularly polarized light LCP1 and the first right-handed circularly polarized light RCP1. Figure 3 and Figure 4 As shown in FIG. 1 , the linearly polarized light emitted by the light source assembly 10 is irradiated to the first geometric phase liquid crystal lens 21 to form a first left-handed circularly polarized light LCP1 with a focal length of +f1 and a first right-handed circularly polarized light with a focal length of −f1.

[0060] Continue to refer Figure 3 , Figure 5 and Figure 6 As shown, the second geometric phase liquid crystal lens 22 is used to convert the first left-handed circularly polarized light LCP1 into the second right-handed circularly polarized light RCP2, and convert the first right-handed circularly polarized light RCP1 into the second left-handed circularly polarized light LCP2. That is, when the first left-handed circularly polarized light LCP1 is irradiated to the second geometric phase liquid crystal lens 22, the second geometric phase liquid crystal lens 22 behaves as a lens with a focal length of -f2, and the first left-handed circularly polarized light LCP1 is converted into the second right-handed circularly polarized light RCP2; when the first right-handed circularly polarized light RCP1 is irradiated to the second geometric phase liquid crystal lens 22, the surface of the second geometric phase liquid crystal lens 22 is a lens with a focal length of +f2, and the first right-handed circularly polarized light RCP1 is converted into the second left-handed circularly polarized light LCP2.

[0061] It should be understood that Figure 3For the convenience of illustration, the overlapping part of the first left-handed circularly polarized light LCP1 and the first right-handed circularly polarized light RCP1, the second left-handed circularly polarized light LCP2 and the second right-handed circularly polarized light RCP2 is only displayed as right-handed circularly polarized light. Figure 7 and Figure 8 , Figure 7 The figure shows the conversion of linear polarized light into the first left-handed circularly polarized light LCP1 and the second right-handed circularly polarized light RCP2. Figure 7 It can be seen that after the linear polarized light passes through the first geometric phase liquid crystal lens 21, the first left-handed circularly polarized light LCP1 converted into a converging spherical wave, whose focal length is the focal length of the first geometric phase liquid crystal lens 21 + f1. When the first left-handed circularly polarized light LCP1 is irradiated to the second geometric phase liquid crystal lens 22, the first left-handed circularly polarized light LCP1 is converted into the second right-handed circularly polarized light RCP2, and the second right-handed circularly polarized light RCP2 is a plane wave. Figure 8 The example shows the conversion of linear polarized light into the first right-handed circularly polarized light RCP1 and the second left-handed circularly polarized light LCP2. Figure 8 It can be seen that by Figure 8 It can be seen that after the linear polarized light passes through the first geometric phase liquid crystal lens 21, the first left-handed circularly polarized light LCP1 converted into a divergent spherical wave, whose focal length is the focal length -f1 of the first geometric phase liquid crystal lens 21. When the first left-handed circularly polarized light LCP1 is irradiated to the second geometric phase liquid crystal lens 22, the first left-handed circularly polarized light LCP1 is converted into a second right-handed circularly polarized light RCP2, and the second left-handed circularly polarized light LCP2 is a divergent spherical wave. In addition, the paths of the formed second left-handed circularly polarized light LCP2 and the second right-handed circularly polarized light RCP2 are the same, so the light intensities of the two circularly polarized lights are also the same.

[0062] Continue to refer Figure 3 , Figure 7 and Figure 8 , after the second left-handed circularly polarized light LCP2 and the second right-handed circularly polarized light RCP2 overlap, they are irradiated to the alignment layer 30. When the second left-handed circularly polarized light LCP2 and the second right-handed circularly polarized light RCP2 overlap and propagate, the second left-handed circularly polarized light LCP2 and the second right-handed circularly polarized light RCP2 interfere to form a linear polarized light irradiating the alignment layer 30, and the linear polarized light forms a light field to irradiate the alignment layer 30. The linear polarized light in the light field changes periodically, and the period of change is a period of change, so as to form a linear polarized light field as shown in FIG. Figure 1 The liquid crystal arrangement direction shown in FIG. 1 corresponds to the changed alignment direction in the alignment layer 30 .

[0063] It can be seen from the above description that the preparation device of the liquid crystal lens provided in the embodiment of the present application forms a light field composed of linear polarized light whose polarization state changes periodically by using the cooperation of the first geometric phase liquid crystal lens 21 and the second geometric phase liquid crystal lens 22, and the period is a change period. Therefore, when it is irradiated on the orientation layer 30 for orientation, the orientation direction can be formed to change periodically, and the period changes periodically. Therefore, when irradiated on the orientation layer 30, an arrangement mode required for the liquid crystal orientation of the lens can be formed. In addition, the exposure optical path of the entire device is simple and reliable, easy to adjust, convenient and flexible. Compared with the dynamic projection of the digital micromirror device in the prior art, the orientation of the orientation layer 30 can be completed after one exposure.

[0064] For reference Fig. 9 and Fig.10 For ease of understanding, the preparation device of the liquid crystal lens provided in the embodiment of the present application is described below in conjunction with Fig. 9 and Fig.10 The principle is introduced in detail.

[0065] When two beams of circularly polarized light of equal intensity and orthogonal rotation are interfered, a light field with a continuously changing polarization state can be obtained, and the period of the light field is related to the angle θ between the two interfering circularly polarized lights. Since the second left-handed circularly polarized light LCP2 is a spherical wave and the second right-handed circularly polarized light RCP2 is a plane wave, the angle between the two circularly polarized lights gradually increases from the center to the edge of the light field, resulting in a gradual decrease in the period of the light field from the center to the edge of the light field.

[0066] like Fig. 9 As shown, assuming that E1 is the second right-handed circularly polarized light RCP2, E2 is the second left-handed circularly polarized light LCP2, and the angle between the two circularly polarized lights is θ, the electric field vectors of the two circularly polarized lights can be expressed as:

[0067]

[0068] Where x, y, z are coordinate vectors, e is the base of natural logarithm, k1 and k2 are wave vectors of E1 and E2 respectively, k1=2π / λ(-sin θ, 0, cosθ), k2=2π / λ(0, 0, 1), and the light field E formed by the interference of two beams can be expressed as

[0069]

[0070] is the phase difference between the two beams, where , λ0 is the wavelength of the laser (also the wavelength of left-handed circularly polarized light, right-handed circularly polarized light and linearly polarized light). When the angle θ between the two beams is very small, cosθ=1 approximately. For example, in the embodiment of the present application, when the maximum value of θ is less than 8°, cosθ>0.99≈1, and the interference light field E formed at this time can be approximately expressed as:

[0071]

[0072] At this time, the polarization state of the interference light field is a linear polarization state, and the angle between the linear polarization direction α and the x-axis is:

[0073]

[0074] The interference field of two orthogonal circular polarization states of equal intensity has uniform light intensity, and its polarization state is a linear polarization state. The direction of the linear polarization state is related to the angle θ and the spatial position x of the two beams of light. The phase difference information between E1 and E2 is converted into the polarization state information of the interference field.

[0075] set up is a period, then there exists

[0076]

[0077] Substituting into α, we have

[0078]

[0079] That is, the period of the light field is related to θ, combined with Fig.10 It can be seen that the angle θ increases from the center to the edge, so the period decreases. Therefore, a periodic light field is formed with a decreasing period from the center to the edge.

[0080] If E1 is a spherical wave and E2 is a plane wave, in a two-dimensional plane, the angle α between the director of the liquid crystal molecule in the geometric phase liquid crystal lens and the xy plane should satisfy ( ), is the radius of the circle, is the distance from the spherical wave source to the interference field, which is also the focal length of the geometric phase liquid crystal lens group 20. Then:

[0081]

[0082] The polarization state distribution of the interference field is

[0083]

[0084]

[0085] That is, the linear polarization direction and radius Related, the cycle size varies with decreases with the increase of .

[0086] When the alignment layer 30 is aligned by the above method, the material of the alignment layer 30 uses a light-controlled alignment material that is sensitive to a linear polarization state, and the light-controlled alignment material can record the polarization information of the light field. In addition, after the light-controlled alignment material molecules are irradiated with linear polarized light, an oriented polymerization cross-linking reaction will occur, which can make the liquid crystal molecules follow the distribution orientation of the linear polarization state, so that the preparation of the geometric phase liquid crystal lens can be realized.

[0087] Continue to refer Figure 7 and Figure 8 When the first left-handed circularly polarized light LCP1 is a spherical wave and the second right-handed circularly polarized light RCP2 is a plane wave, the distance between the first geometric phase liquid crystal lens 21 and the second geometric phase liquid crystal lens 22 can be adjusted.

[0088] like Figure 7 As shown, for the first left-handed circularly polarized light LCP1, the focal length of the first geometric phase liquid crystal lens 21 is f1, and the focal length of the second geometric phase liquid crystal lens 22 is -f2. At this time, the overall focal length f' of the geometric phase liquid crystal lens group 20 is

[0089] ,

[0090] That is, the second right-handed circularly polarized light RCP2 appears as a focal length of Spherical waves.

[0091] like Figure 8 As shown, for the second right-handed circularly polarized light RCP2, the focal length of the first geometric phase liquid crystal lens 21 is -f1, and the focal length of the second geometric phase liquid crystal lens 22 is f2. At this time, the focal length f′ of the geometric phase liquid crystal lens group 20 is:

[0092] , ;

[0093] The geometric phase liquid crystal lens group 20 does not change the propagation direction of the light, so the second right-handed circularly polarized light RCP2 is emitted as a plane wave.

[0094] It can be seen from the above scheme that in the embodiment of the present application, the first geometric phase liquid crystal lens 21 and the second geometric phase liquid crystal lens 22 are combined into a geometric phase liquid crystal lens group 20 to convert linear polarized light into two circularly polarized lights with equal light intensity and opposite rotation directions, and make one of the two circularly polarized lights a plane wave and the other a spherical wave. When the two circularly polarized lights interfere to form linear polarization, since one of the two circularly polarized lights is a plane wave and the other is a spherical wave, the angles of the two circularly polarized lights are different at different positions in the light field, so that the linear polarization direction of the formed linear polarized light changes and changes periodically, and the period is also a changing period. And finally, the demand for changes in the orientation direction of the orientation layer 30 is met.

[0095] For reference Fig.11 The present application also provides a method for preparing a liquid crystal lens. In the preparation method, the above Figure 3 The method is prepared by the preparation device exemplified in the example. The method specifically comprises the following steps:

[0096] Step 001: Spin coating an alignment material on a substrate to form an alignment layer on the substrate;

[0097] Step 002: Use any of the above-mentioned liquid crystal lens manufacturing devices to irradiate the alignment layer for exposure and alignment.

[0098] In the above technical solution, by using the cooperation of the first geometric phase liquid crystal lens and the second geometric phase liquid crystal lens, a linear polarized light with periodic polarization state changes is formed, and the period of the linear polarized light is a change period. Therefore, when it is irradiated on the orientation layer for orientation, the orientation direction can be formed to change periodically, and the periodic change. The entire exposure light path is simple and reliable, easy to adjust, convenient and flexible.

[0099] According to the different structures of liquid crystal lenses, geometric liquid crystal lenses can be divided into active and passive types. Therefore, their corresponding preparation methods can be divided into the following two types according to the structure of the liquid crystal lens.

[0100] like Fig.12 As shown, the active geometric liquid crystal lens comprises a substrate 1, an ITO (IndiumTinOxide, tin-doped indium oxide) layer 4, an orientation layer 3, a liquid crystal layer 2 and the like. The above structure is the same as the structure of the active geometric phase liquid crystal lens in the prior art, and will not be described in detail here. In the corresponding preparation method, it specifically includes:

[0101] Step 01: Before spin coating the alignment material on the substrate, prepare a transparent conductive layer on the substrate;

[0102] Step 02: Spin coating an alignment material on the substrate to form an alignment layer on the substrate;

[0103] Specifically, the photo-controlled alignment material is spin-coated on the substrate to form a photo-controlled alignment film with a thickness of tens of nanometers on the surface of the substrate.

[0104] Step 03: After spin coating the alignment material on the substrate, the two substrates are aligned to form a liquid crystal box for accommodating liquid crystals;

[0105] Step 04: Use the above-mentioned liquid crystal lens preparation device to irradiate the alignment layer for exposure and alignment;

[0106] Step 05: After exposing the alignment layer, liquid crystal material is poured into the liquid crystal cell.

[0107] In the above preparation method, by using the first geometric phase liquid crystal lens and the second geometric phase liquid crystal lens, a linear polarized light with periodic polarization state changes is formed, and the period of the linear polarized light is a change period. Therefore, when it is irradiated on the orientation layer for orientation, the orientation direction can be formed to change periodically, and the period changes. The entire exposure light path is simple and reliable, easy to adjust, convenient and flexible.

[0108] In addition, the preparation method also includes cleaning the substrate before executing step 01. The specific steps include: using a substrate cleaning agent, anhydrous ethanol, and deionized ultrasonic cleaning of the substrate; using an oven to dry the substrate, and using an ultraviolet sampling processor to clean the substrate to remove organic particles left on the substrate. This is to clean the substrate to the maximum extent and improve the cleanliness of the substrate.

[0109] like Fig.13 As shown, the passive geometric liquid crystal lens comprises a substrate 5, an orientation layer 6, a liquid crystal coating 7 and the like. The above structure is the same as the structure of the passive geometric phase liquid crystal lens in the prior art, and will not be described in detail here. In the corresponding preparation method, it specifically includes:

[0110] Step 1: Spin coating an alignment material on a substrate to form an alignment layer on the substrate;

[0111] Specifically, the photo-controlled alignment material is spin-coated on the substrate to form a photo-controlled alignment film with a thickness of tens of nanometers on the surface of the substrate.

[0112] Step 2: using the above-mentioned liquid crystal lens preparation device to irradiate the alignment layer for exposure and alignment;

[0113] Step 3: After exposing the alignment layer, coating the liquid crystal material on the substrate.

[0114] In the above preparation method, by using the first geometric phase liquid crystal lens and the second geometric phase liquid crystal lens, a linear polarized light with periodic polarization state changes is formed, and the period of the linear polarized light is a change period. Therefore, when it is irradiated on the orientation layer for orientation, the orientation direction can be formed to change periodically, and the period changes. The entire exposure light path is simple and reliable, easy to adjust, convenient and flexible.

[0115] In addition, the preparation method also includes cleaning the substrate before executing step 1, and the specific steps include: using a substrate cleaning agent, anhydrous ethanol, and deionized ultrasonic cleaning of the substrate; using an oven to dry the substrate, and using an ultraviolet sampling processor to clean the substrate to remove organic particles left on the substrate, so as to clean the substrate to the maximum extent and improve the cleanliness of the substrate.

[0116] One or more embodiments of this specification are intended to cover all such substitutions, modifications and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of one or more embodiments of this specification should be included in the scope of protection of this disclosure.

[0117] The above are only specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A device for preparing a liquid crystal lens, It is characterized in that It includes a light source component and a geometric phase liquid crystal lens component arranged along the light path; wherein, The light source assembly is used to emit linearly polarized light; The geometric phase liquid crystal lens assembly includes a first geometric phase liquid crystal lens and a second geometric phase liquid crystal lens with different focal lengths; The first geometric phase liquid crystal lens is used to convert the linear polarized light into a first left-handed circularly polarized light and a first right-handed circularly polarized light; wherein the first left-handed circularly polarized light is a converging spherical wave, and the first right-handed circularly polarized light is a diverging spherical wave; The second geometric phase liquid crystal lens is used to convert the first left-handed circularly polarized light into a second right-handed circularly polarized light, and convert the first right-handed circularly polarized light into a second left-handed circularly polarized light; wherein the second left-handed circularly polarized light interferes with the second right-handed circularly polarized light to form a linearly polarized light irradiating the alignment layer; the light field formed by the linearly polarized light changes periodically, and the period is a period of change; wherein the second left-handed circularly polarized light is a divergent spherical wave, and the second right-handed circularly polarized light is a plane wave; The light field satisfies: The period of the light field gradually decreases from the center of the light field to the edge of the light field; The second left-handed circularly polarized light interferes with the second right-handed circularly polarized light to form linearly polarized light; along the X direction, the period of the linearly polarized light satisfies: ； Wherein, θ is the angle between the second left-handed circularly polarized light and the second right-handed circularly polarized light; α is the linear polarization direction; λ0 is the wavelength of the linearly polarized light, is the period of the linear polarized light; x is the plane coordinate of the position where the linear polarized light irradiates; The geometric phase liquid crystal lens assembly satisfies: ； d=f 2 -f 1 ; Wherein, f′ is the focal length of the liquid crystal lens assembly, f 1 is the focal length of the first geometric phase liquid crystal lens, f 2 is the focal length of the second geometric phase liquid crystal lens, and d is the distance between the first geometric phase liquid crystal lens and the second geometric phase liquid crystal lens.

2. The device for preparing a liquid crystal lens according to claim 1, It is characterized in that The polarization direction of the linearly polarized light satisfies: ； ； Wherein, f′ is the focal length of the geometric phase liquid crystal lens assembly; π is the circumference of a circle; x and y are the plane coordinates of the position of the alignment layer irradiated by the linearly polarized light; and λ0 is the wavelength of the linearly polarized light.

3. The device for preparing a liquid crystal lens according to claim 1, It is characterized in that The light source assembly comprises a laser, a beam expander lens, a collimator lens and a polarizer arranged along an optical path.

4. A method for preparing a liquid crystal lens, It is characterized in that The following steps are involved: Spin coating an alignment material on a substrate to form an alignment layer on the substrate; The liquid crystal lens manufacturing device according to any one of claims 1 to 3 is used to irradiate the alignment layer for exposure alignment.

5. The method for preparing a liquid crystal lens according to claim 4, It is characterized in that The method further comprises: Before spin coating the alignment material on the substrate, a transparent conductive layer is prepared on the substrate; After spin coating the alignment material on the substrate, the two substrates are aligned to form a liquid crystal cell for containing liquid crystal; After the alignment layer is exposed, liquid crystal material is poured into the liquid crystal cell.

6. The method for preparing a liquid crystal lens according to claim 4, It is characterized in that Also includes: After the alignment layer is exposed, a liquid crystal material is coated on the substrate.

7. The method for preparing a liquid crystal lens according to any one of claims 4 to 6, It is characterized in that Also includes: Use substrate cleaning agent, anhydrous ethanol, and deionized ultrasonic cleaning of the substrate; The substrate is dried in an oven, and cleaned with an ultraviolet sampling processor to remove organic particles remaining on the substrate.

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