Integrated system applicable to multi-mode polarization interference grating exposure

Abstract

An integrated system applicable to multi-mode polarization interference grating exposure. The system comprises: a laser (1), a collimation and beam expansion system (2), a first polarization regulation and control unit (3), a second polarization regulation and control unit (4), a first variable aperture (5), a second variable aperture (6), a spatial light absorption plate (7), a first reflective optical module (8), a second reflective optical module (9) and a substrate (10). The system aims to realize a more compact, stable and easily adjustable high-precision exposure apparatus by simplifying an optical path structure, unifying an optical path length and introducing a spatially partitioned polarization modulation method. By no longer relying on traditional PBS beam-splitting structures, the system directly generates a required interference field by means of a single-beam expanded laser source, and uses a symmetric dual-reflection interference structure, thereby greatly enhancing the symmetry and stability of the system.

Description

An integrated system for multi-mode polarization interference grating exposure Technical Field

[0001] This invention relates to an integrated system suitable for exposure of multi-mode polarization interference gratings, belonging to the field of grating fabrication and holographic optics technology. Background Technology

[0002] Against the backdrop of the rapid development of optical display technologies such as Augmented Reality (AR), polarization volume holographic gratings (PVHGs) have gradually become an important material for constructing high-performance optical devices due to their flexible control over the polarization state, direction, and phase of light. In the fabrication process of PVHGs, obtaining a stable, coherent, and specifically polarized two-beam interference light field is a key factor determining the performance of the grating.

[0003] Existing PVHG exposure systems mostly rely on optical beam splitters (such as polarizing beam splitters PBS) combined with a series of waveplates (λ / 2, λ / 4) to achieve interference between two beams with different polarization directions through complex optical path deflection and polarization control. However, this structure has the following main problems:

[0004] Complex optical path structure: After beam splitting, PBS (Polarizing Beam Splitter) often needs to be folded by a mirror to achieve spatial overlap, resulting in a large space occupation, poor stability, and difficulty in modular design.

[0005] Difficulty in adjusting optical path difference: After two beams of light pass through different optical elements and paths, there is often an optical path difference, which requires the addition of a delay plate or fine-tuning structure for compensation, increasing the difficulty of system debugging.

[0006] Insufficient exposure stability: Since the system involves multiple reflection and polarization conversion elements, even slight mechanical or thermal disturbances may disrupt the interference stability and affect the exposure quality.

[0007] Poor environmental adaptability: Traditional structures are more sensitive to platform vibration, temperature and humidity changes, which limits their consistency and reliability in large-scale industrial applications. Summary of the Invention

[0008] Objective: To overcome the shortcomings of existing technologies, this invention provides an integrated system suitable for multi-mode polarization interference grating exposure. The aim is to achieve a more compact, stable, and easily adjustable high-precision exposure device by simplifying the optical path structure, unifying the optical path, and introducing spatially partitioned polarization modulation. The system no longer relies on the traditional PBS beam-splitting structure; instead, it directly generates the desired interference field through a single-beam extended laser source and employs a symmetrical double-reflection interference structure, greatly improving the system's symmetry and stability.

[0009] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0010] In a first aspect, an integrated system suitable for exposure of multi-mode polarization interference gratings includes: a laser, a collimation and beam expansion system, a first polarization control unit, a second polarization control unit, a first variable aperture, a second variable aperture, a spatial light-absorbing plate, a first reflective optical module, a second reflective optical module, and a substrate.

[0011] After the laser emits a laser beam, it enters the collimation and beam expanding system set below. The middle beam after beam expansion is limited by the spatial light-absorbing plate set below. One side of the beam after beam expansion is modulated by the first polarization control unit set below to form left-handed circularly polarized light. The other side of the beam after beam expansion is modulated by the second polarization control unit set below to form right-handed circularly polarized light. The left-handed circularly polarized light passes through the first variable aperture set below and enters the first reflection optical module set below. The right-handed circularly polarized light passes through the second variable aperture set below and enters the second reflection optical module set below. The beams reflected by the two reflection optical modules illuminate the substrate and interfere to achieve exposure.

[0012] The first reflective optical module and the second reflective optical module are disposed on both sides of the substrate.

[0013] As a preferred embodiment, the laser is a single-longitudinal-mode HeCd laser.

[0014] As a preferred embodiment, the collimating and beam expanding system adopts a double-lens Galilean telescope structure.

[0015] As a preferred embodiment, both the first polarization control unit and the second polarization control unit adopt waveplate arrays or SLM polarization modulation units.

[0016] As a preferred embodiment, both the first variable aperture and the second variable aperture are adjustable mechanical apertures.

[0017] As a preferred embodiment, the angle between the first reflective optical module and the substrate plane is 90°+θ. x The angle between the second reflective optical module and the substrate plane is 90°+θ. y θ x θ y The value range is 5°–45°.

[0018] As a preferred option, the space light-absorbing panel is made of blackened aluminum alloy.

[0019] As a preferred embodiment, the substrate is quartz glass coated with a photo-alignment material.

[0020] Secondly, an integrated system suitable for exposure of multi-mode polarization interference gratings includes: a laser, a collimation and beam expansion system, a first polarization control unit, a second polarization control unit, a first variable aperture, a second variable aperture, a first reflective optical module, a second reflective optical module, and a substrate.

[0021] After the laser emits a laser beam, it enters the collimation and beam expansion system set below. One side of the expanded beam is modulated by the first polarization control unit set below to form first polarized light, and the other side of the expanded beam is modulated by the second polarization control unit set below to form second polarized light. The polarization directions of the first polarized light and the second polarized light are different. After the first polarized light passes through the first variable aperture set below, it enters the first reflection optical module set below. After the second polarized light passes through the second variable aperture set below, it enters the second reflection optical module set below. The beams reflected by the two reflection optical modules and the expanded middle beam illuminate the substrate and interfere to achieve exposure.

[0022] The first reflective optical module and the second reflective optical module are disposed on adjacent sides of the substrate.

[0023] As a preferred embodiment, the angle between the first reflective optical module and the substrate plane is 90°+θ. x The angle between the second reflective optical module and the substrate plane is 90°+θ. y θ x θ y The value range is 5°–45°.

[0024] Beneficial Effects: This invention provides an integrated system suitable for multi-mode polarization interference grating exposure, belonging to the fields of grating fabrication and holographic optics. The system uses a single-beam laser source incident perpendicularly, which, after beam expansion, forms a large-area uniform spot. Polarization is controlled in the left and right regions using a spatially partitioned waveplate group or a liquid crystal spatial light modulator (SLM), generating a pair of circularly polarized beams with opposite chirality (LCP (left-hand circularly polarized light) / RCP (right-hand circularly polarized light)). These beams are reflected by symmetrically arranged mirrors and superimposed on the substrate surface to form a vector interference light field. This system employs a symmetrical double-reflection interference structure, eliminating the traditional PBS beam-splitting path, effectively simplifying the optical path, eliminating optical path difference, and improving system symmetry and interference immunity. The angle between the mirrors and the substrate (90°+θ) is adjusted. x 90°+θ yThis system precisely controls the grating period; it utilizes an adjustable aperture to block stray light, combined with an anti-reflective substrate and a high-precision rotating stage, ensuring interference fringe uniformity (error <2%). The system also supports SLM-based vector polarization field modulation, suitable for generating complex grating structures; and can be optionally extended to a three-beam interference configuration for generating two-dimensional grating patterns in a single exposure. This invention features a compact structure, symmetrical optical path, and flexible adjustment, making it particularly suitable for the efficient fabrication and mass production of high-precision, large-area polarimetric gratings in augmented reality (AR), optical displays, and diffraction elements.

[0025] Compared with existing technologies, the advantages of this invention are as follows:

[0026] Compared with traditional optical path designs, this invention eliminates the PBS beam splitter and dual optical path, adopts a symmetrical dual-reflection structure and introduces a spatial polarization control method, which greatly simplifies the optical path structure and eliminates problems such as inconsistent optical path length, complex debugging and mechanical instability.

[0027] Meanwhile, by introducing a high-precision mirror structure and SLM control techniques, this invention can flexibly generate various periodic vector light fields, achieving higher precision and more diverse grating fabrication. The system supports two-dimensional structures as an optional extension configuration, covering grating design scenarios from unidirectional linear gratings to two-dimensional dot lattices.

[0028] This invention features a compact structure and easy debugging, making it particularly suitable for vertical optical path layouts. It also boasts enhanced vibration resistance and environmental adaptability, making it applicable to the fabrication and industrial production of large-area polarization gratings in fields such as AR displays, optical waveguides, and imaging devices. Attached Figure Description

[0029] Figure 1 is a schematic diagram of the overall structure of the integrated system disclosed in this invention.

[0030] Figure 2 is a three-dimensional structural schematic diagram of the symmetrical double reflection interference structure of the present invention.

[0031] Figure 3 shows a two-dimensional planar view of the symmetrical double-reflection interference structure and a schematic diagram of its angular relationship with the exposure optical path.

[0032] Figure 4 is a schematic diagram of the structure of the substrate of the present invention.

[0033] Figure 5 is a schematic diagram of a two-dimensional grating exposure structure using a biaxial interference configuration in the optional structure of the present invention.

[0034] Figure 6 is a schematic diagram of the one-dimensional grating structure exposed by the symmetrical double-reflection interference structure of the present invention.

[0035] Figure 7 is a schematic diagram of the two-dimensional grating structure exposed by the biaxial interference configuration of the present invention. Detailed Implementation

[0036] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 protection scope of the present invention.

[0037] The present invention will be further described below with reference to specific embodiments.

[0038] Example 1:

[0039] This embodiment introduces an integrated system suitable for multi-mode polarization interference grating exposure to realize a one-dimensional grating structure, as shown in Figure 1, including: a laser 1, a collimation and beam expansion system 2, a first polarization control unit 3, a second polarization control unit 4, a first variable aperture 5, a second variable aperture 6, a spatial light-absorbing plate 7, a first reflective optical module 8, a second reflective optical module 9, and a substrate 10.

[0040] After laser 1 emits a laser beam, it enters the collimating and beam expanding system 2 located below. The expanded middle beam is confined by the spatial light-absorbing plate 7 located below. One side of the expanded beam is modulated by the first polarization control unit 3 located below to form left-handed circularly polarized light, and the other side of the expanded beam is modulated by the second polarization control unit 4 located below to form right-handed circularly polarized light. The left-handed circularly polarized light passes through the first variable aperture 5 located below and then enters the first reflective optical module 8 located below. The right-handed circularly polarized light passes through the second variable aperture 6 located below and then enters the second reflective optical module 9 located below. The beams reflected by the two reflective optical modules illuminate the substrate 10 and undergo interference to achieve exposure. The first reflective optical module 8 and the second reflective optical module 9 are located on both sides of the substrate 10.

[0041] Furthermore, the laser uses a single-longitudinal-mode HeCd laser as the interference source, with an output wavelength of 457nm, an output power of 150mW, a beam diameter of 62.6mm, and a coherence length of 300mm, ensuring high contrast and stability of the interference fringes.

[0042] The laser's output port is mounted downwards on top of the optical platform and connected to a horizontal adjustment micro-stage via a dedicated mounting bracket, ensuring that the laser axis is strictly perpendicular to the substrate surface with an error not exceeding ±0.1°. The laser body is thermally controlled and vibration-damped via an active water-cooling module and a vibration-isolated base, ensuring output light intensity and coherence stability.

[0043] Furthermore, in order to obtain a large-sized uniform light spot to cover the entire exposure area (e.g., 90mm×90mm), the laser beam emitted from the light outlet enters the collimation and beam expansion system vertically in sequence.

[0044] Preferably, the collimation and beam-expanding system adopts a double-lens Galilean telescope structure, including a negative lens (focal length f1-50mm) and a positive lens (focal length f2+250mm), with a beam-expanding magnification of 5x. The collimation and beam-expanding system is mounted on an adjustable vertical slide rail via a lens tube, supporting fine-tuning of the optical axis and correction of the focal position. All lens components are coated with anti-reflection coatings to reduce reflection loss.

[0045] Furthermore, both the first polarization control unit and the second polarization control unit can be waveplate arrays or SLM polarization modulation units.

[0046] The waveplate array includes a half-wave plate (HWP) and a quarter-wave plate (QWP), with the half-wave plate arranged above the quarter-wave plate.

[0047] The half-wave plate and quarter-wave plate are made of yttrium vanadate (YVO4) or quartz. The working delays of the two wave plates are λ / 2 and λ / 4, respectively, with a center wavelength of λ of 457 nm. The delay error is less than λ / 100, and the fast axis adjustment accuracy is better than 0.5°. The wave plates are embedded in a rotatable bracket, and the installation position is adjusted by an XYZ micro-displacement stage to ensure that the modulated circularly polarized light has high purity and stability.

[0048] The SLM polarization modulation unit is a high-order function of the SLM. It achieves multi-beam, multi-task, and high-efficiency optical field modulation through partition control. This means that the entire pixel area of ​​the SLM is divided into multiple independently controlled blocks, and each block can be loaded with different phase or amplitude modulation patterns.

[0049] The SLM polarization modulation unit features spatial partitioning capability and grayscale driving accuracy exceeding 8 bits. The SLM is mounted within a standard optical frame and the required polarization phase pattern (LCP for left-handed circularly polarized light) or (RCP for right-handed circularly polarized light) is programmed. To prevent thermal instability, the SLM module is equipped with a thin-film water-cooled heat dissipation backplate.

[0050] Furthermore, both the first and second variable apertures are adjustable mechanical apertures that block stray light in the middle area, allowing only the light beams reflected by the first and second reflective optical modules to interfere, thus ensuring the clarity and uniformity of the interference fringes.

[0051] Furthermore, the spatial light-absorbing plate is on the same horizontal plane as the first and second variable apertures. A black metal light-shielding plate or a detachable rectangular aperture is set in the middle region of the expanded beam field to block the central part of the laser, allowing only the beams in the left and right sides to continue propagating after modulation. The light-shielding plate is made of blackened aluminum alloy with a light transmittance of <0.5%, smooth edges without burrs, and a size that matches the beam width. The installation method uses magnetic guide rails or threaded adjustable clamps to ensure positional stability and ease of replacement.

[0052] Furthermore, both the first and second reflective optical modules are configured as reflectors. The first reflective optical module serves as an X-mirror, and the second reflective optical module serves as a Y-mirror. The X-mirror and Y-mirror are reflectors with high flatness, silver-plated or reinforced aluminum reflective surfaces, reflectivity >95%, and surface shape error better than λ / 20, where λ represents the center wavelength of the reflector.

[0053] The X-ray and Y-ray mirrors are fixed on independent rotating platforms on the left and right sides, forming an adjustable angle (90° + θ) with the surface of the horizontally positioned substrate. x With 90°+θ γ θ x θ γ The value range is 5°–45°. The back of the reflector has three-point support fine-tuning screws, and the frame adopts a lockable high-precision optical bracket. To ensure interference angle matching, the X / Y mirror bases are connected to the angle division circle and the electronic goniometer, respectively, and real-time fine adjustment and periodic reproduction are achieved through an external handwheel.

[0054] The angle θ between the X-ray mirror, the Y-ray mirror, and the substrate x and θ y It can be adjusted independently to meet the needs of different grating periods. Fine-tuning of the angle is achieved through a precision rotary stage (adjustment accuracy 0.01°) to ensure the uniformity and consistency of the grating period.

[0055] Furthermore, the substrate is a 1mm thick quartz glass coated with a photo-alignment material (such as a photosensitive polymer) with chamfered edges. The substrate is placed horizontally on a high-precision vacuum adsorption platform that supports four-dimensional adjustment (XY-pitch-rotation). A highly permeable microporous silicone pad is attached to the surface of the platform, ensuring a flat and even substrate adhesion through negative pressure adsorption.

[0056] To reduce stray light interference, the surface of the vacuum adsorption platform is coated with a multi-layer SiO2 / Si3N4 anti-reflection coating, achieving a target reflectivity of less than 0.5%. A height-adjustable vibration isolation mechanism is installed beneath the vacuum adsorption platform to enhance the overall system's resistance to environmental disturbances.

[0057] The substrate is fixed by a multi-degree-of-freedom vacuum adsorption platform, which supports pitch, rotation, and horizontal displacement adjustment. A glass sheet coated with photo-alignment material (1 mm thick) is fixed to the platform surface by vacuum adsorption, and its angle can be adjusted in real time via the platform's scale.

[0058] The anti-reflective coating of the vacuum adsorption platform is a multilayer silicon dioxide / silicon nitride composite film system, prepared by magnetron sputtering, ensuring a reflectivity of less than 0.5% in the visible light band. In the experiment, by adjusting the platform angle, a specific angle (e.g., 30°–60°) is formed between the glass slide and the incident beam, and an aperture is used to block unnecessary reflection paths, allowing only the reflected beams from the X-mirror and Y-mirror to superimpose and interfere in the substrate area.

[0059] Example 2:

[0060] This embodiment introduces an integrated system suitable for multi-mode polarization interference grating exposure to realize a two-dimensional grating structure, including: a laser 1, a collimation and beam expansion system 2, a first polarization control unit 3, a second polarization control unit 4, a first variable aperture 5, a second variable aperture 6, a first reflection optical module 8, a second reflection optical module 9, and a substrate 10.

[0061] After the laser 1 emits a laser beam, it enters the collimation and beam expansion system 2 set below. The beam on one side after expansion is modulated by the first polarization control unit 3 set below to form first polarized light, and the beam on the other side after expansion is modulated by the second polarization control unit 4 set below to form second polarized light. The polarization directions of the first polarized light and the second polarized light are different. After the first polarized light passes through the first variable aperture 5 set below, it enters the first reflection optical module 8 set below. After the second polarized light passes through the second variable aperture 6 set below, it enters the second reflection optical module 9 set below. The beams reflected by the two reflection optical modules and the expanded middle beam illuminate the substrate 10 and interfere to achieve exposure.

[0062] The first reflective optical module 8 and the second reflective optical module 9 are disposed on adjacent sides of the substrate 10.

[0063] Furthermore, the waveplate array employs half-wave plates (HWP).

[0064] Example 3:

[0065] This embodiment describes the working process of grating exposure in an integrated system suitable for multi-mode polarization interference grating exposure, specifically including:

[0066] This invention employs a single-longitudinal-mode HeCd laser (wavelength 457nm, power 150mW) as the interference source. The laser beam is incident vertically downwards onto the collimating and expanding system, forming a uniform light spot covering the target exposure area. To ensure the system's optical path symmetry and optical field stability, this system eliminates the traditional PBS+dual-path structure and adopts a single-beam partitioned modulation scheme.

[0067] After beam expansion, the light spot is confined by a spatial light-absorbing plate, leaving only two sub-regions on the left and right to enter different polarization modulation units (such as waveplate arrays or liquid crystal spatial light modulators). The polarization modulation units set in the left and right regions respectively convert the beam into left-hand circularly polarized light (LCP) and right-hand circularly polarized light (RCP), providing the necessary polarization basis for subsequent interference to form a vector grating.

[0068] As shown in Figure 2, the symmetrical double-reflection interference structure comprises two high-precision mirrors (an X-plane mirror and a Y-plane mirror), symmetrically mounted on both sides of the substrate. The mirror surfaces are coated with a high-reflectivity (>95%) metal film, and the mirror surface flatness is better than λ / 20 (λ=531nm). The angle between the X-mirror and the substrate plane is 90°+θ. x The angle between the Y-mirror and the substrate plane is 90°+θ. y , (θ x and θ y (Can be adjusted independently).

[0069] As shown in Figure 3, in the two-dimensional planar diagram of the symmetrical double-reflection interference structure, the reflected beams from the X-mirror and Y-mirror form an interference light field on the substrate surface. The incident angles of the two beams are... and The mirror tilt angle satisfies the following geometric relationship: If the exposure time is θ x =θ y The period Λ of the interference light field x It can be determined by the following formula: Where, λ r This is the operating wavelength of the single-longitudinal-mode laser. θ is adjusted via a precision rotary table. x and θ y The grating period can be precisely controlled. The grating structure pattern obtained by exposure is shown in Figure 6.

[0070] As shown in Figure 4, the substrate is fixed using a multi-degree-of-freedom vacuum adsorption platform, which supports pitch, rotation, and horizontal displacement adjustment. A glass sheet coated with a photo-alignment material (1 mm thick) is fixed to the platform surface via vacuum adsorption. The upper surface of the platform is coated with a multilayer silicon dioxide / silicon nitride composite anti-reflection film (reflectivity <0.5%) to reduce stray light interference. In the experiment, the angle between the glass sheet and the incident beam is adjusted in real time using an angle scale (e.g., 30°–60°) to ensure the uniformity of the light field in the exposure area.

[0071] In addition, to avoid reflections or stray light interference from non-target areas, this system introduces an adjustable mechanical aperture in the interference path, retaining only the main interference beams reflected by the X-mirror and Y-mirror.

[0072] Example 4:

[0073] This embodiment describes the working process of a programmable polarization vector light field exposure based on a liquid crystal spatial light modulator (SLM) for an integrated system suitable for multi-mode polarization interference grating exposure, specifically including:

[0074] To achieve more flexible and dynamic polarization modulation, this invention preferably employs a liquid crystal spatial light modulator (SLM) as the partitioned polarization modulation element. The SLM can perform high-precision spatial control of the phase and polarization state of the incident light, thereby generating a complex vector light field.

[0075] Liquid crystal spatial light modulators (SLMs) are arranged in the left and right beam regions after beam expansion to replace waveplate arrays, modulating the phase and polarization direction of the beam respectively, thus achieving the conversion between left-hand circularly polarized light (LCP) and right-hand circularly polarized light (RCP). By precisely controlling the SLM grayscale driving signal, the polarization state distribution can be dynamically adjusted to meet the diverse grating structure design requirements.

[0076] The use of SLM not only enhances system flexibility but also significantly reduces the complexity and adjustment difficulty of traditional fixed optical components. During system debugging, the phase response curve of the SLM needs to be calibrated to ensure that the input grayscale corresponds to the expected phase shift, thus avoiding modulation errors from affecting interference quality.

[0077] Example 5:

[0078] This embodiment describes a working process for two-dimensional grating exposure based on a dual-axis interference structure, suitable for multi-mode polarization interference grating exposure, specifically including:

[0079] In an optional embodiment of the present invention, the exposure system may also employ a biaxial interference structure with three beams to achieve single exposure of a two-dimensional grating. As shown in Figure 5, the laser beam emitted by the laser is collimated and expanded vertically downwards into the substrate area via a beam-expanding system. One beam directly irradiates the substrate, while the other two beams are respectively positioned on the left and right sides, forming angles of 90°+θ with the substrate plane. x and 90°+θ y The X-mirror and Y-mirror reflect light and then superimpose it on the same area, forming a two-dimensional spatial interference pattern.

[0080] To achieve high-contrast interference fringes, half-wave plates can be placed in the reflection paths of the X-mirror and Y-mirror, respectively. By adjusting their fast axis direction, the polarization state of the beam can be controlled, thereby enhancing the useful components in the interference field and suppressing unwanted cross-term interference. Interference period Λ x and Λ y The angle θ between the reflecting mirrors x and θ y The controlled entity satisfies the following relationship:

[0081] Compared to traditional dual-beam interference structures, this structure can generate two-dimensional grating patterns in a single exposure without rotating the sample or multiple exposures (see Figure 7), making it suitable for the fabrication of high-throughput, high-precision grating structures.

[0082] Combined with other supporting units in this invention (such as anti-reflective film platform, aperture stray light control, multi-degree-of-freedom fixture, etc.), this structure can significantly improve interference uniformity and stability, and is suitable for applications of polarization holographic gratings in augmented reality (AR) and high-end optical component manufacturing.

[0083] In order to solve the problems in the prior art, some studies have attempted to simplify the optical path, such as arranging the optical path vertically to improve stability, or reducing optical path mismatch through coaxial structure. However, these methods are still difficult to fundamentally eliminate the dependence on PBS beam splitting and complex polarization control.

[0084] Furthermore, PVHGs require extremely high precision in exposure conditions, especially when fabricated on high-resolution photosensitive materials (such as liquid crystal photopolymers), where the interference field needs to possess excellent coherence, uniformity, and stability. Therefore, developing a novel exposure optical path with natural optical path consistency, a compact symmetrical structure, and spatial polarization control capabilities has become a key technological breakthrough for achieving high-performance PVHG fabrication.

[0085] This invention proposes a novel polarimetric volume holographic grating (PVHG) exposure system. Its core lies in the organic integration of single-beam vertical incidence, spatially partitioned polarization modulation, and a symmetrical double-reflection interference structure to construct a highly symmetrical, consistent optical path, and easily adjustable interference light field. Furthermore, the system supports expansion to a two-dimensional interference structure based on a three-beam Lloyd-type reflection configuration to meet the single-exposure requirements of complex grating patterns.

[0086] Specifically, this system eliminates the traditional PBS beam splitting path, directing the collimated laser beam vertically downwards, which is then expanded to form a large-area uniform spot. Different polarization modulation structures (such as waveplate arrays or liquid crystal modulators) are introduced into the left and right regions of this spot, respectively, converting them into left-hand circularly polarized (LCP) and right-hand circularly polarized (RCP) beams. The two circularly polarized beams are then adjusted for their incident angles by symmetrically arranged mirrors (forming an adjustable double-reflection interference structure), ultimately interfering on a horizontally placed photosensitive substrate to form the desired vector grating structure. In an optional configuration, the system can also introduce a direct beam and the reflected light from the X / Y mirrors to form a three-beam interference field, used to generate a two-dimensional grating structure in a single operation.

[0087] This solution effectively avoids problems such as inconsistent optical path lengths, structural asymmetry, and complex debugging inherent in traditional two-beam systems, significantly improving the overall stability and anti-interference capabilities of the system. Especially in a vertical arrangement, it significantly reduces the impact of environmental vibrations on the stability of interference fringes. By introducing an optional three-beam interference structure, the system also possesses higher adaptability to two-dimensional structures and improved fabrication efficiency. This invention is applicable to advanced optical systems such as augmented reality (AR) that require extremely high grating precision and uniformity, and can also be extended to the industrial fabrication of vector waveguides, diffractive optical elements, and complex polarization coding structures.

[0088] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An integrated system suitable for multi-mode polarization interferometric grating exposure, characterized by: Comprising: laser, collimation beam expander system, first polarization control unit, second polarization control unit, first variable diaphragm, second variable diaphragm, spatial light absorber, first reflective optical module, second reflective optical module and substrate; After the laser emits a laser beam, it enters the collimation beam expander system arranged below. The intermediate beam after beam expansion is limited by the spatial light absorber arranged below. The one side beam after beam expansion is modulated by the first polarization control unit arranged below to form left-handed circularly polarized light. The other side beam after beam expansion is modulated by the second polarization control unit arranged below to form right-handed circularly polarized light. The left-handed circularly polarized light passes through the first variable diaphragm arranged below and is incident on the first reflective optical module arranged below. The right-handed circularly polarized light passes through the second variable diaphragm arranged below and is incident on the second reflective optical module arranged below. The light beams reflected by the two reflective optical modules are irradiated on the substrate to realize exposure by interference. The first reflective optical module and the second reflective optical module are arranged on both sides of the substrate.

2. The integrated system suitable for multi-mode polarization interferometric grating exposure according to claim 1, wherein: The laser adopts a single longitudinal mode HeCd laser.

3. The integrated system suitable for multi-mode polarization interferometric grating exposure according to claim 1, wherein: The collimation beam expander system adopts a double-lens Galilean telescope structure.

4. The integrated system suitable for multi-mode polarization interferometric grating exposure according to claim 1, wherein: The first polarization control unit and the second polarization control unit both adopt a wave plate array or an SLM polarization modulation unit.

5. The integrated system suitable for multi-mode polarization interferometric grating exposure according to claim 1, wherein: The first variable diaphragm and the second variable diaphragm both adopt an adjustable mechanical diaphragm.

6. The integrated system suitable for multi-mode polarization interferometric grating exposure according to claim 1, wherein: The first reflective optical module forms an angle of 90°+θ with the substrate plane x The second reflective optical module forms an angle of 90°+θ with the substrate plane y The values of θ x , θ y range from 5° to 45°.

7. The integrated system suitable for multi-mode polarization interferometric grating exposure according to claim 1, wherein: The spatial light absorber adopts blackened aluminum alloy.

8. The integrated system suitable for multi-mode polarization interferometric grating exposure according to claim 1, wherein: The substrate is quartz glass coated with light orientation material.

9. An integrated system suitable for multi-mode polarization interferometric grating exposure, characterized by: Comprising: laser, collimation beam expander system, first polarization control unit, second polarization control unit, first variable diaphragm, second variable diaphragm, first reflective optical module, second reflective optical module and substrate; After the laser emits a laser beam, it enters the collimation beam expander system arranged below. The one side beam after beam expansion is modulated by the first polarization control unit arranged below to form first polarized light. The other side beam after beam expansion is modulated by the second polarization control unit arranged below to form second polarized light. The polarization directions of the first polarized light and the second polarized light are different. The first polarized light passes through the first variable diaphragm arranged below and is incident on the first reflective optical module arranged below. The second polarized light passes through the second variable diaphragm arranged below and is incident on the second reflective optical module arranged below. The light beams reflected by the two reflective optical modules and the intermediate beam after beam expansion are irradiated on the substrate to realize exposure by interference. The first reflective optical module and the second reflective optical module are arranged on two adjacent sides of the substrate.

10. The integrated system suitable for multi-mode polarization interferometric grating exposure according to claim 9, wherein: The first reflective optical module forms an angle of 90°+θ with the substrate plane x The second reflective optical module forms an angle of 90°+θ with the substrate plane y The values of θ x , θ y range from 5° to 45°.

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