Geometric phase liquid crystal zoom lens based on polarizer grating and preparation method thereof

Abstract

The invention relates to the technical field of liquid crystal optical devices and self-adaptive optics, and particularly discloses a geometric phase liquid crystal zoom lens based on a polarization volume grating and a preparation method thereof. The geometric phase liquid crystal zoom lens comprises a polarization conversion and management system, a first PVG lens layer, an electric control liquid crystal dynamic modulation layer and a second PVG lens layer; and the first PVG lens layer, the electric control liquid crystal dynamic modulation layer and the second PVG lens layer are integrated into an optical module. According to the electronic control zoom lens, through the sandwich structure that the electronic control liquid crystal dynamic modulation layer is clamped by the first PVG lens layer and the second PVG lens layer which are symmetrically arranged, the electronic control zoom lens which is compact in structure, low in driving voltage, rapid in response and excellent in imaging quality is achieved; the driving voltage is obviously reduced, the response speed is increased, the size is reduced, the imaging quality is improved, the bottleneck problem existing in the field for a long time is solved, and the technical advantages are prominent.

Description

Technical Field

[0001] This invention relates to the fields of liquid crystal optical devices and adaptive optics, specifically to a geometric phase liquid crystal zoom lens based on a polarizing grating and its fabrication method. Background Technology

[0002] With the rapid development of near-eye display technologies such as augmented reality, the demand for thinner, more integrated, and smarter optical systems is becoming increasingly urgent. Traditional optical lenses rely on curved surface refraction, making it difficult to achieve a thin and flat structure. Furthermore, their fixed focal length fails to meet the personalized visual needs of different users or usage scenarios. Liquid crystal lenses, as electrically controllable and adjustable optical devices, offer a solution to these problems. Existing liquid crystal lenses are mainly based on the gradient refractive index effect of nematic liquid crystals, forming an approximately parabolic phase distribution within the liquid crystal layer through electrode structures. However, these lenses typically suffer from high driving voltage, slow response speed, limited aperture, and high-order aberrations, restricting their application in high-performance display systems.

[0003] In recent years, optical elements based on geometric phase have attracted widespread attention. Polarizing body gratings (PVGs) are a typical example of geometric phase elements, achieving precise control of the phase of incident circularly polarized light by spatially modulating the optical axis orientation of liquid crystal molecules. Unlike traditional gratings, PVGs possess advantages such as near-100% diffraction efficiency, strong polarization selectivity, and wide angular bandwidth. Currently, research and applications of PVGs mainly focus on optical deflection (gratings) and waveguide coupling. Although some studies have used similar principles to fabricate liquid crystal polarizing body holographic cylindrical lenses, their function is limited, with a fixed focal length, making electronically controlled dynamic zoom impossible.

[0004] How to combine the advantages of PVG's high efficiency and precise phase control with the electronic control characteristics of liquid crystal materials to design and fabricate an electronically controlled zoom lens with a compact structure, low driving voltage, fast response, and excellent image quality is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a geometric phase liquid crystal zoom lens based on a polarizing grating and its fabrication method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The geometric phase liquid crystal zoom lens based on a polarizer grating comprises, in sequence from the light incident direction, a polarization conversion and management system, a first PVG lens layer, an electro-controlled liquid crystal dynamic modulation layer, and a second PVG lens layer. The first PVG lens layer, the electro-controlled liquid crystal dynamic modulation layer, and the second PVG lens layer are integrated into an optical module, wherein: Both the first PVG lens layer and the second PVG lens layer are liquid crystal polymer films, and the optical axis orientation of the liquid crystal molecules inside them is continuously axially symmetric in a spatial distribution on the plane, forming a geometric phase lens with a fixed focal length. The electro-controlled liquid crystal dynamic modulation layer is a liquid crystal cell encapsulating nematic liquid crystal. By applying different driving voltages, the polarization state of light waves passing through this layer can be controlled, or a dynamic phase delay can be added to the light waves. The polarization conversion and management system is used to convert unpolarized or arbitrarily polarized incident light into circularly polarized light with a specific rotation direction, and can switch the rotation direction of the circularly polarized light under electronic control.

[0007] Optionally, the first PVG lens layer, the electro-controlled liquid crystal dynamic modulation layer, and the second PVG lens layer are stacked sequentially, and adjacent layers are directly bonded or bonded by optical adhesive to form a sandwich structure optical module.

[0008] Optionally, both the first PVG lens layer and the second PVG lens layer can focus circularly polarized light with a specific rotation direction and defocus light with the opposite rotation direction by an equal amount.

[0009] Optionally, the polarization conversion and management system includes at least a linear polarizer and an electrically controlled liquid crystal retarder. The linear polarizer and the electrically controlled liquid crystal retarder convert arbitrary incident light into electrically controllable circularly polarized light, providing polarization selectivity control for the first PVG lens layer and the second PVG lens layer.

[0010] Optionally, the liquid crystal cell thickness of the electrically controlled liquid crystal dynamic modulation layer is 10 μm, and the encapsulated nematic liquid crystal is a high birefringence nematic liquid crystal.

[0011] Optionally, both the upper and lower substrates of the liquid crystal cell are coated with ITO transparent electrodes for applying a lateral or longitudinal electric field.

[0012] Optionally, a method for fabricating a geometric phase liquid crystal zoom lens based on a polarizing grating is provided for fabricating the geometric phase liquid crystal zoom lens described above, and the fabrication method includes the following steps: Fabrication of the first PVG lens layer and the second PVG lens layer: S1: Optical glass with a refractive index of 1.5 is selected as the substrate. After cleaning, a bright yellow dye photoalignment layer is coated on its surface and dried. It is then placed in a polarization holographic exposure system for exposure processing. S2: Construct a single spatial light modulator and an orthogonally polarized dual-beam interference system; S3: Using 457nm laser collimated light, a spatial light modulator modulates one collimated light beam into a signal light carrying the phase function of an ideal lens, and the other beam is an orthogonally polarized plane reference light, so that the signal light carrying the phase function of the ideal lens interferes with the other plane reference light. S4: Two beams of light interfere with each other on the surface of the photoalignment layer to record an axisymmetric continuous optical axis alignment pattern; S5: Spin-coating a mixture of nematic liquid crystal monomer RM257, chiral agent R / S5011 and photoinitiator onto the alignment layer of the exposed substrate; S6: The substrate is uniformly irradiated with ultraviolet light to cure the mixture of nematic liquid crystal monomer RM257, chiral agent R / S5011 and photoinitiator mixed liquid that are spin-coated on the substrate surface, forming a PVG geometric phase lens liquid crystal polymer film with no shrinkage, high stability and fixed focal length. S7: Repeat the preparation process of S1-S6 above, and repeat the preparation of the second PVG lens layer with the exact same process parameters to ensure that the focal length, orientation distribution and polarization response of the first PVG lens layer and the second PVG lens layer are completely consistent.

[0013] Fabrication of the electro-controlled liquid crystal dynamic modulation layer: A liquid crystal cell with a thickness of 10 μm was fabricated. The interior of the liquid crystal cell was filled with a nematic liquid crystal with high birefringence. Both the upper and lower substrates of the liquid crystal cell were coated with ITO transparent electrodes.

[0014] Device integration: The first PVG lens layer, the electro-controlled liquid crystal dynamic modulation layer, and the second PVG lens layer are aligned under an optical alignment instrument to ensure that their optical axes are completely coincident. Then, they are directly bonded or bonded together with UV-cured optical adhesive to form an integral module, thereby fabricating a geometric phase liquid crystal zoom lens.

[0015] Optionally, the bright yellow dye is BY or SD1.

[0016] Optionally, the polarization holographic exposure system employs orthogonal polarization dual-beam interference, with one beam loaded with an ideal lens parabolic phase and the other beam serving as a planar reference beam for recording the axisymmetric focused phase.

[0017] The beneficial effects of this invention are: 1. In this invention, a sandwich structure with a 10μm ultrathin electro-controlled liquid crystal dynamic modulation layer sandwiched between a symmetrically arranged first PVG lens layer and a second PVG lens layer is used to realize an electro-controlled zoom lens with a compact structure, low driving voltage, fast response, and excellent imaging quality. Compared with traditional gradient refractive index liquid crystal lenses, this invention significantly reduces driving voltage, improves response speed, reduces volume, and improves imaging quality, solving a long-standing bottleneck problem in the field and possessing outstanding technical advantages.

[0018] 2. In this invention, a full-plane thin film and an ultra-thin liquid crystal cell are integrated, with no curved lenses or mechanical moving parts, resulting in an overall thin and flat design that is highly compatible with miniaturized systems such as AR / VR near-eye displays.

[0019] 3. In this invention, a uniform electric field is used to drive polarization state switching, which eliminates the need for complex gradient electrodes and high voltage driving. The operating voltage is low, the power consumption is small, and the driving circuit is simple.

[0020] 4. In this invention, zoom is achieved by rapidly switching the polarization direction of liquid crystal molecules. The cell thickness is only 10μm, and the measured focal length switching response time is <20ms, which is far superior to traditional liquid crystal lenses.

[0021] 5. In this invention, based on the ideal parabolic geometric phase design, there are no higher-order aberrations; PVG has high diffraction efficiency, the overall optical efficiency is >70%, and the imaging is clear and has high contrast. Attached Figure Description

[0022] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram of the geometric phase liquid crystal zoom lens based on a polarizing grating proposed in this invention.

[0024] In the figure: 1. First PVG lens layer; 2. Second PVG lens layer; 3. Electro-controlled liquid crystal dynamic modulation layer. Detailed Implementation

[0025] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Reference Figure 1 The geometric phase liquid crystal zoom lens based on a polarizer grating comprises, in sequence from the light incident direction, a polarization conversion and management system, a first PVG lens layer 1, an electro-controlled liquid crystal dynamic modulation layer 3, and a second PVG lens layer 2. The first PVG lens layer 1 and the electro-controlled liquid crystal dynamic modulation layer 3 are integrated into an optical module, wherein: The first PVG lens layer 1 and the second PVG lens layer 2 are both liquid crystal polymer films. The optical axis orientation of the liquid crystal molecules inside them is continuously axially symmetric in a spatial distribution on the plane, forming a geometric phase lens with a fixed focal length. The optical structures of the first PVG lens layer 1 and the second PVG lens layer 2 are exactly the same, that is, they have the same focal length f0 and the same polarization selectivity.

[0027] The electro-controlled liquid crystal dynamic modulation layer 3 is a liquid crystal cell that encapsulates nematic liquid crystal. By applying different driving voltages, the polarization state of the light wave passing through this layer can be controlled, or a dynamic phase delay can be added to the light wave. This electro-controlled liquid crystal dynamic modulation layer 3 is the key to realizing the zoom function.

[0028] The polarization conversion and management system is used to convert unpolarized or arbitrarily polarized incident light into circularly polarized light with a specific rotation direction, and can switch the rotation direction of the circularly polarized light under electronic control.

[0029] The above design has the following advantages: This invention utilizes a sandwich structure consisting of a symmetrically arranged first PVG lens layer 1 and a second PVG lens layer 2 sandwiching a 10μm ultrathin electronically controlled liquid crystal dynamic modulation layer 3. This structure achieves an electronically controlled zoom lens with a compact structure, low driving voltage, fast response, and excellent imaging quality, as specifically demonstrated below: Compact structure: It adopts a full-plane thin film and ultra-thin liquid crystal cell integration, without curved lenses and mechanical moving parts, and the whole is lightweight and flat, which is highly compatible with miniaturized systems such as AR / VR near-eye displays.

[0030] Low driving voltage: The polarization state switching is driven by a uniform electric field, eliminating the need for complex gradient electrodes and high-voltage driving. It features low operating voltage, low power consumption, and a simple driving circuit.

[0031] Fast response: Zooming is achieved by rapidly switching the polarization direction of liquid crystal molecules. The cell thickness is only 10μm, and the measured focal length switching response time is <20ms, which is far superior to traditional liquid crystal lenses.

[0032] Excellent imaging quality: Based on an ideal parabolic geometric phase design, there are no high-order aberrations; PVG has high diffraction efficiency, with an overall optical efficiency of >70%, resulting in clear imaging and high contrast.

[0033] Compared with traditional gradient refractive index liquid crystal lenses, this invention significantly reduces driving voltage, improves response speed, reduces size, and improves imaging quality, solving a long-standing bottleneck problem in the field and possessing outstanding technical advantages.

[0034] As a technical optimization of the present invention, the first PVG lens layer 1, the electro-controlled liquid crystal dynamic modulation layer 3 and the second PVG lens layer 2 are stacked in sequence, and the adjacent layers are directly bonded or bonded by optical adhesive to form an optical module with a sandwich structure.

[0035] As a technical optimization of the present invention, both the first PVG lens layer 1 and the second PVG lens layer 2 can focus circularly polarized light with a specific rotation direction and defocus light with the opposite rotation direction by an equal amount.

[0036] As a technical optimization of the present invention, the polarization conversion and management system includes at least a linear polarizer and an electrically controlled liquid crystal delay unit. The linear polarizer and the electrically controlled liquid crystal delay unit convert arbitrary incident light into electrically controllable circularly polarized light, providing polarization selectivity control for the first PVG lens layer 1 and the second PVG lens layer 2.

[0037] The polarization conversion and management system in this embodiment adopts orthogonal polarization dual-beam interference. One beam is loaded with the parabolic phase of an ideal lens, and the other beam is a plane reference light used to record the axisymmetric focused phase, rather than the vortex phase. Compared with related systems in the prior art, it only uses a single spatial light modulator. The optical path is the orthogonal polarization interference of the lens wavefront and the plane wave. The structure is simpler and designed specifically for geometric phase zoom lenses.

[0038] As a technical optimization of the present invention, the liquid crystal cell thickness of the electrically controlled liquid crystal dynamic modulation layer 3 is 10 μm, and the encapsulated nematic liquid crystal is a high birefringence nematic liquid crystal. The formula for calculating the high birefringence of the nematic liquid crystal in this embodiment is: Δn = ne no (ne is the unusual refractive index, no is the ordinary refractive index) reflects the magnitude of optical anisotropy of the liquid crystal. For high birefringence, Δn ≥ 0.15-0.20.

[0039] As a technical optimization of the present invention, both the upper and lower substrates of the liquid crystal cell are plated with ITO transparent electrodes for applying a lateral or longitudinal electric field.

[0040] As a technical optimization of the present invention, a method for fabricating a geometric phase liquid crystal zoom lens based on a polarizing grating is provided for fabricating the geometric phase liquid crystal zoom lens described above, and the fabrication method includes the following steps: Fabrication of the first PVG lens layer 1 and the second PVG lens layer 2: S1: Optical glass with a refractive index of 1.5 is selected as the substrate. After cleaning, a bright yellow dye photoalignment layer is coated on its surface and dried. It is then placed in a polarization holographic exposure system for exposure processing. S2: Construct a single spatial light modulator and an orthogonally polarized dual-beam interference system; S3: Using a 457nm laser collimated light, a spatial light modulator modulates one collimated light beam into a signal light carrying the phase function of an ideal lens, and the other beam is an orthogonally polarized plane reference light, so that the signal light carrying the phase function of the ideal lens interferes with the other plane reference light. S4: Two beams of light interfere with each other on the surface of the photoalignment layer to record an axisymmetric continuous optical axis alignment pattern; S5: Spin-coating a mixture of nematic liquid crystal monomer RM257, chiral agent R / S5011 and photoinitiator onto the alignment layer of the exposed substrate; S6: The substrate is uniformly irradiated with ultraviolet light to cure the mixture of nematic liquid crystal monomer RM257, chiral agent R / S5011 and photoinitiator mixed liquid that are spin-coated on the substrate surface, forming a PVG geometric phase lens liquid crystal polymer film with no shrinkage, high stability and fixed focal length. S7: Repeat the preparation process of S1-S6 above, and repeat the preparation of the second PVG lens layer 2 with the exact same process parameters to ensure that the focal length, orientation distribution and polarization response of the first PVG lens layer 1 and the second PVG lens layer 2 are completely consistent.

[0041] In this embodiment, the ideal lens phase function is derived using the parabolic spherical wave phase distribution formula φ(r) = πr2 / (λf), loaded by a spatial light modulator and exposed by polarization holographic interference, forms the continuous axisymmetric optical axis orientation required for the geometric phase lens.

[0042] Fabrication of the electro-controlled liquid crystal dynamic modulation layer 3: A liquid crystal cell with a thickness of 10 μm is fabricated. The interior of the liquid crystal cell is filled with a nematic liquid crystal with high birefringence. The upper and lower substrates of the liquid crystal cell are coated with ITO transparent electrodes.

[0043] Device integration: The first PVG lens layer 1, the electro-controlled liquid crystal dynamic modulation layer 3, and the second PVG lens layer 2 are aligned under an optical alignment instrument to ensure that their optical axes are completely coincident. Then, they are directly bonded or bonded together with UV-cured optical adhesive to form an integral module, thereby fabricating a geometric phase liquid crystal zoom lens.

[0044] As a technical optimization of the present invention, the bright yellow dye is BY or SD1.

[0045] As a technical optimization of the present invention, the polarization holographic exposure system adopts orthogonal polarization dual-beam interference, one beam is loaded with an ideal lens parabolic phase, and the other beam is a planar reference light used to record the axisymmetric focused phase.

[0046] Geometric phase liquid crystal zoom lens system test: In this invention, when the geometric phase liquid crystal zoom lens prepared above is subjected to system testing, it is combined with a polarization management system consisting of a linear polarizer and a switchable rotation direction liquid crystal retarder. During testing, a 632.8nm He-Ne laser is used as the light source. When the polarization management system outputs right-handed circularly polarized light and no voltage is applied to the electro-controlled liquid crystal layer, both the first PVG lens layer 1 and the second PVG lens layer 2 converge the light, resulting in a total focal length of 25cm. When the electro-controlled liquid crystal dynamic modulation layer 3 is voltage-adjusted to a half-wave plate, it changes the polarization rotation direction of the light between the first PVG lens layer 1 and the second PVG lens layer 2, causing the second PVG lens layer 2 to defocus, canceling out the effect of the first PVG lens layer 1. The system then behaves as a flat plate with an infinity focal length. By precisely controlling the voltage of the electro-controlled liquid crystal dynamic modulation layer 3, a phase delay related to the square of the radius is generated. This delay is linearly superimposed on the fixed phase of the PVG, allowing continuous adjustment of the focal length from 25cm to infinity. The measured optical efficiency (transmitted light intensity / incident light intensity) is higher than 70%, and the focal length switching response time is less than 20 milliseconds.

[0047] The focus switching response time mentioned above is less than 20 milliseconds. The underlying principle behind this fast response is as follows: 1. The working mechanism is rapid polarization state switching, rather than refractive index gradient reconstruction: This invention rapidly changes the polarization direction of light through the electro-controlled liquid crystal layer, realizing the function switching from "focusing + focusing" to "focusing + defocusing" between the first PVG lens layer 1 and the second PVG lens layer 2. It does not require the establishment of a spatial gradient refractive index distribution in the electro-controlled liquid crystal dynamic modulation layer 3, thus avoiding the slow response process of traditional liquid crystal lenses.

[0048] 2. Uses a 10μm ultra-thin liquid crystal cell: The liquid crystal response time is proportional to the square of the cell thickness, and the ultra-thin structure greatly shortens the molecular deflection path and response time.

[0049] 3. High birefringence liquid crystals only require a small angle of deflection to achieve the required phase delay and polarization conversion, with small molecular rotation angles and high speeds.

[0050] 4. Uniform electric field driving across the entire domain: A uniform electric field is applied to the upper and lower ITO electrodes, causing the liquid crystal molecules to deflect synchronously across the entire domain without local delay or orientation disorder.

[0051] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A geometric phase liquid crystal zoom lens based on a polarizing grating, characterized in that, The geometric phase liquid crystal zoom lens, from the direction of light incidence, includes a polarization conversion and management system, a first PVG lens layer (1), an electro-controlled liquid crystal dynamic modulation layer (3), and a second PVG lens layer (2). The first PVG lens layer (1), the electro-controlled liquid crystal dynamic modulation layer (3), and the second PVG lens layer (2) are integrated into an optical module, wherein: The first PVG lens layer (1) and the second PVG lens layer (2) are both liquid crystal polymer films. The optical axis orientation of the liquid crystal molecules inside them is continuously axially symmetric in a spatial distribution on the plane, forming a geometric phase lens with a fixed focal length. The electro-controlled liquid crystal dynamic modulation layer (3) is a liquid crystal cell that encapsulates a nematic liquid crystal. By applying different driving voltages, the polarization state of the passing light wave can be controlled, or a dynamic phase delay can be added to the light wave. The polarization conversion and management system is used to convert unpolarized or arbitrarily polarized incident light into circularly polarized light with a specific rotation direction, and can switch the rotation direction of the circularly polarized light under electronic control.

2. The geometric phase liquid crystal zoom lens based on a polarizer grating according to claim 1, characterized in that, The first PVG lens layer (1), the electro-controlled liquid crystal dynamic modulation layer (3) and the second PVG lens layer (2) are stacked in sequence, and the adjacent layers are directly bonded or bonded by optical adhesive to form an optical module with a sandwich structure.

3. The geometric phase liquid crystal zoom lens based on a polarizer grating according to claim 1, characterized in that, Both the first PVG lens layer (1) and the second PVG lens layer (2) can focus circularly polarized light with a specific rotation direction and defocus light with the opposite rotation direction.

4. The geometric phase liquid crystal zoom lens based on a polarizer grating according to claim 1, characterized in that, The polarization conversion and management system includes at least a linear polarizer and an electrically controlled liquid crystal delay unit. The linear polarizer and the electrically controlled liquid crystal delay unit convert arbitrary incident light into electrically controllable circularly polarized light, providing polarization selectivity control for the first PVG lens layer (1) and the second PVG lens layer (2).

5. The geometric phase liquid crystal zoom lens based on a polarizing grating according to claim 1, characterized in that, The liquid crystal cell thickness of the electronically controlled liquid crystal dynamic modulation layer (3) is 10 μm, and the encapsulated nematic liquid crystal is a high birefringence nematic liquid crystal.

6. The geometric phase liquid crystal zoom lens based on a polarizer grating according to claim 5, characterized in that, The upper and lower substrates of the liquid crystal cell are both plated with ITO transparent electrodes for applying a lateral or longitudinal electric field.

7. A method for fabricating a geometric phase liquid crystal zoom lens based on a polarizing grating, characterized in that, The method for fabricating the geometric phase liquid crystal zoom lens according to claims 1-6 includes the following steps: Fabrication of the first PVG lens layer (1) and the second PVG lens layer (2): S1: Optical glass with a refractive index of 1.5 is selected as the substrate. After cleaning, a bright yellow dye photoalignment layer is coated on its surface and dried. It is then placed in a polarization holographic exposure system for exposure processing. S2: Construct a single spatial light modulator and an orthogonally polarized dual-beam interference system; S3: Using 457nm laser collimated light, a spatial light modulator modulates one collimated light beam into a signal light carrying the phase function of an ideal lens, and the other beam is an orthogonally polarized plane reference light, so that the signal light carrying the phase function of the ideal lens interferes with the other plane reference light. S4: Two beams of light interfere with each other on the surface of the photoalignment layer to record an axisymmetric continuous optical axis alignment pattern; S5: Spin-coating a mixture of nematic liquid crystal monomer RM257, chiral agent R / S5011 and photoinitiator onto the alignment layer of the exposed substrate; S6: The substrate is uniformly irradiated with ultraviolet light to cure the mixture of nematic liquid crystal monomer RM257, chiral agent R / S5011 and photoinitiator mixed liquid that are spin-coated on the substrate surface, forming a stable, non-shrinking PVG geometric phase lens liquid crystal polymer film with a fixed focal length. S7: Repeat the above preparation process S1-S6, and repeat the preparation of the second PVG lens layer (2) with the same process parameters, so that the focal length, orientation distribution and polarization response of the first PVG lens layer (1) and the second PVG lens layer (2) are completely consistent. Fabrication of the electro-controlled liquid crystal dynamic modulation layer (3): A liquid crystal cell with a thickness of 10 μm was fabricated. The interior of the liquid crystal cell was filled with a nematic liquid crystal with high birefringence. Both the upper and lower substrates of the liquid crystal cell were coated with ITO transparent electrodes. Device integration: The first PVG lens layer (1), the electro-controlled liquid crystal dynamic modulation layer (3) and the second PVG lens layer (2) are aligned under an optical alignment instrument so that their optical axes are completely coincident. Then they are directly bonded or bonded together with UV-cured optical adhesive to form an integral module, thereby preparing a geometric phase liquid crystal zoom lens.

8. The method for fabricating a geometric phase liquid crystal zoom lens based on a polarizing grating according to claim 7, characterized in that, The bright yellow dye is BY or SD1.

9. The method for fabricating a geometric phase liquid crystal zoom lens based on a polarizing grating according to claim 7, characterized in that, The polarization holographic exposure system employs orthogonal polarization dual-beam interference, with one beam loaded with an ideal lens for parabolic phase and the other beam serving as a planar reference beam for recording axisymmetric focused phase.

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