Method and system for manufacturing polarizing body holographic grating (PVG) lens and PVG lens

Abstract

The invention relates to a method and a system for manufacturing a polarizing body holographic grating (PVG) lens. The method comprises the following steps: a) providing a PVG lens blank; b) scanning on the PVG lens blank by using a first wavelength laser beam along a preset cutting path to form a stress concentration line; and c) scanning along the same cutting path by using a laser beam with a second wavelength, and applying thermal stress loading to the stress concentration line to guide the crack to expand from the stress concentration line so as to separate the lens blank along the cutting path. According to the invention, a two-step separation method of internal preset fracture path and external thermal shock guiding is adopted. A first wavelength laser beam (such as ultrafast laser of picosecond and the like) can form an accurate and lossless microscopic modified chain as a stress concentration line in a substrate through nonlinear absorption under the condition of not damaging the surface of a material due to the cold working characteristic of the first wavelength laser beam. The surface micro-cracks are eradicated from the source. And a second wavelength laser beam (such as infrared laser of COs and the like) generates a moving and high-gradient thermal stress field on the surface of the substrate along a preset path by utilizing the thermal effect of the second wavelength laser beam. And the stress field accurately acts on the internal fragile stress concentration line to guide cracks to controllably and smoothly expand, so that mechanical-contact-free guided fracture is realized.

Description

Technical Field

[0001] This invention relates to the field of precision machining technology for optical components, and in particular to a method and system for manufacturing PVG lenses by non-destructive, high-precision cutting from composite optical sheets using the synergistic effect of multiple lasers. Background Technology

[0002] Polarizing holographic gratings (PVG) lenses, as an emerging high-performance optical element, demonstrate application potential in cutting-edge fields such as augmented reality (AR), virtual reality (VR) displays, and automotive head-up displays (HUDs) due to their unique light field manipulation capabilities. PVG lenses are typically composed of multi-layered composite materials, with their core functional layers being extremely sensitive to mechanical stress, contaminants, and edge defects.

[0003] Traditional lens cutting methods, such as mechanical scribing wheel cutting or diamond saw blade cutting, are contact processing methods that inevitably produce microcracks, chipping, and residual stress at the lens edges. These defects can seriously affect the optical performance and long-term reliability of the lens. At the same time, the dust and debris generated during processing can easily contaminate the lens surface and functional coatings, leading to a decrease in yield.

[0004] To address these issues, the industry has begun experimenting with laser cutting. However, while conventional laser thermal cutting (such as high-power continuous laser ablation) is non-contact, its heat-affected zone (HAZ) creates a molten and resolidified layer around the cut, leading to thermal stress concentration and poor edge quality. This also fails to meet the requirements of high-precision optical lenses such as PVG. Furthermore, for composite optical components like PVG, which are extremely sensitive to edge defects, achieving a high-precision, non-destructive, pollution-free, and highly efficient cutting method remains a core challenge for current manufacturing technology.

[0005] Therefore, there is an urgent need for a PVG lens manufacturing method and supporting equipment that can achieve high precision, non-destructive, pollution-free, high efficiency and high automation, in order to break through the bottleneck of existing technology. Summary of the Invention

[0006] The manufacturing method of a polarizing holographic grating (PVG) lens provided in this application adopts the following technical solution:

[0007] A method for manufacturing a polarizing holographic grating (PVG) lens, comprising:

[0008] a) Provide a PVG lens blank (1), the PVG lens blank comprising at least one substrate and a functional film layer disposed thereon;

[0009] b) Contour engraving step: On the PVG lens blank, a first wavelength laser beam is used to scan along a preset cutting path to form a stress concentration line;

[0010] c) Guided cracking step: Using a second wavelength laser beam to scan along the same cutting path, thermal stress is applied to the stress concentration line to guide the crack to propagate from the stress concentration line, thereby separating the lens blank along the cutting path.

[0011] This application provides a method for manufacturing a polarizing holographic grating (PVG) lens, aiming to solve problems such as edge microcracks, thermal damage, and contamination that exist in the prior art when cutting PVG lenses. The method employs a two-step collaborative separation method of "internal pre-set fracture path + external thermal shock guidance." Specifically, the method includes:

[0012] First, a first-wavelength laser beam (such as a picosecond ultrafast laser) is used. Leveraging its extremely short pulse length, a "cold processing" characteristic is employed to form a precise and non-destructive micro-modification chain along a predetermined path within the PVG lens blank through nonlinear absorption effects, without damaging the material surface. This chain serves as a stress concentration line. This step fundamentally eliminates the possibility of microcracks caused by surface scratches.

[0013] Subsequently, a second wavelength laser beam (such as an infrared laser like CO2) is used, leveraging its long wavelength's efficient absorption by the substrate material's surface, to scan along the same pre-defined path. This generates a moving, high-gradient thermal stress field on the substrate surface. This stress field precisely acts on the stress concentration line—the structurally weakest point—pre-defined by the first wavelength laser, guiding the crack to propagate controllably and smoothly along this path, ultimately achieving non-contact, "guided" fracture. Compared to traditional technologies, this solution has the following advantages:

[0014] Compared to mechanical scribing, it pre-defines the path through internal modification rather than surface scratching, thus eliminating the source of surface microcracks at the root.

[0015] Compared to ablation cutting, it avoids a large amount of material vaporization, thus avoiding thermal damage, molten recast layer and debris contamination near the cut. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of an automated manufacturing system for a polarizer holographic grating (PVG) lens provided in the first embodiment of this application;

[0017] Figure 2 This is a schematic diagram of the fabrication process for a polarizing holographic grating (PVG) lens.

[0018] Explanation of reference numerals in the attached drawings: 1. PVG lens blank; 10. First sheet; 20. Second sheet; 12. Substrate; 14. Functional film layer; 16. Peripheral sealing strip; 18. Auxiliary optical medium; 180. Transparent substrate layer; 182. Solid optical adhesive layer; 2. Worktable; 3. Laser system; 4. Optical system; 5. Scanning galvanometer; 7. Vision alignment subsystem; 8. Automatic lamination mechanism; 6. Central control system; 31. First laser; 32. Second laser; 33. Third laser; 42. Dichroic mirror; 41. Shaping lens; 21. Support platform; 23. Clamping mechanism; 81. Three-axis movement mechanism. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only possible technical implementations of the present invention and not all possible implementations. Those skilled in the art can obtain other embodiments in conjunction with the embodiments of the present invention without creative effort, and these embodiments are also within the protection scope of the present invention.

[0020] Example 1

[0021] This embodiment discloses a precision manufacturing method for precision optical components, particularly polarizing holographic grating (PVG) lenses. This method aims to solve the dual problems of microcracks introduced by mechanical cutting and thermal damage introduced by conventional laser cutting in the prior art: while traditional mechanical scribing cutting can achieve separation, it inevitably introduces uncontrollable microcracks and edge stress; while traditional laser thermal ablation cutting can achieve non-contact processing, it brings significant heat-affected zone (HAZ), material recasting, and thermal stress damage. This invention achieves a microcrack-free and thermal damage-free cutting effect through a step-by-step synergistic laser process, thereby improving product yield and edge mechanical reliability.

[0022] Please refer to the following: Figure 1 and Figure 2 The specific steps of this method are as follows:

[0023] A composite PVG lens blank 1 is provided. The PVG lens blank 1 includes a substrate 12 and a functional film layer 14. The PVG lens blank 1 is a single substrate, which needs to be cut into dices to obtain a polarizer holographic grating (PVG) lens of the required size. The functional film layer 14 is typically composed of organic materials such as oriented liquid crystal polymers.

[0024] b) Using a first laser beam, a first wavelength laser beam is used to scan along a preset cutting path to form a stress concentration line.

[0025] This step involves creating a stress concentration line within the PVG lens blank 1, with effectively controlled width and depth uniformity at the microscopic scale, without damaging the surrounding material. This line serves as a "preset track" for guiding the precise propagation of cracks.

[0026] To achieve this goal, this embodiment preferably uses the first laser 31 in laser system 3, which is an ultrafast laser, such as a picosecond laser. The fundamental reason for choosing an ultrafast laser (such as a picosecond or femtosecond laser) is that its pulse width is much smaller than the electron-phonon coupling time inside the material (i.e., the time it takes for heat to be transferred from electrons to the crystal lattice). This allows energy to modify or remove the material before the heat diffuses, thereby achieving "cold processing" or "thermal processing" and physically eliminating the generation of heat-affected zones.

[0027] In this embodiment, a green picosecond laser with a wavelength of 532 nanometers is selected. This wavelength is chosen based on the following considerations: 532-nanometer green light can be effectively absorbed by a transparent substrate (such as glass) through a nonlinear multiphoton absorption effect, thereby precisely and controllably forming internal micro-modification points at the focal point, constituting a stress concentration line, while not causing damage to the substrate surface and functional film layer.

[0028] The operating parameters of the first laser 31 are set as follows: repetition frequency in the range of 500 kHz to 2 MHz (1 MHz in this example), and single pulse energy in the range of 1 to 10 microjoules (μJ) (5 μJ in this example). After the laser beam is collimated and focused by the shaping system, it scans along the preset cutting path.

[0029] In this embodiment, a composite scanning mode of "trepanning" is used to form the stress concentration line. Specifically, the focal point of the laser beam does not perform a simple single-line scan, but rather rotates at high speed in a spiral or ring around the central axis in a plane perpendicular to its incident direction with a preset small radius (e.g., 5-20 micrometers). At the same time, the geometric center of this rotational motion moves stably at a speed of 500 mm / s along a preset macroscopic cutting path (e.g., a circle with a diameter of 50 mm). Compared to simple single-line scanning, the key advantages of this composite motion mode are: First, it evenly distributes the total energy required to form the modified chain within a tiny annular region, thus avoiding uncontrollable thermal damage that may be caused by excessive energy concentration at a single point, and physically ensuring the high uniformity and continuity of the stress concentration line at the microscale; Second, high-speed rotation means that at any point on the cutting path, the material will be subjected to high-frequency pulse impacts from multiple different angles. This "multi-angle attack" method can more effectively sever the microscopic bonds inside the material, thereby forming an ideal stress concentration line with a more fragile structure and more conducive to the precise propagation of subsequent cracks at a lower single-pulse energy.

[0030] Ultimately, this scanning method can form a microgroove or internal modified chain with highly uniform width and depth. By effectively avoiding localized heat accumulation, the original physical state of the material around the guide path is preserved, thus ensuring that the edges of the formed guide groove are neat, and its heat-affected zone (HAZ) can be precisely controlled to below 2 micrometers.

[0031] c) Using a second laser beam, controllable thermal stress is applied to guide the cleavage.

[0032] Ultimately, the tensile stress field generated by the main thermal scan acts on the guide line, ensuring that the crack can stably and controllably penetrate the entire substrate thickness along the preset path in one go, achieving precise separation of the lens blank, thereby obtaining a PVG lens with a preset contour shape and size.

[0033] In this embodiment, the preset cutting path is designed as a racetrack-shaped profile suitable for the frame of augmented reality (AR) glasses, and its size can be precisely controlled, for example, 45mm in length and 28mm in width.

[0034] The purpose of this step is to apply a uniform and controllable tensile stress field to the entire PVG lens blank 1. This stress field acts precisely on the "preset track" constructed in step b), driving the crack to propagate stably and smoothly along this track, thereby achieving material separation. For this purpose, this embodiment uses the second laser 32 in the laser system 3, which is a long-wavelength infrared laser, such as a carbon dioxide (CO2) laser. A CO2 laser with a wavelength of 10.6 micrometers is chosen because the substrate 12 has a near 100% absorption rate at this wavelength, and the energy can be efficiently absorbed by the very shallow surface layer, thereby rapidly forming a significant, localized temperature rise.

[0035] The CO2 laser operates in continuous wave (CW) mode with a power range adjustable from 10 to 50 watts (W) (25 W in this example). Its spot is shaped into a circular spot with a diameter of 1.0–2.0 mm (1.2 mm in this example). This laser spot precisely follows the stress-guided path established in step b), scanning at a speed set between 300–800 mm / s (500 mm / s in this example). As the laser heat source moves, the material in front of it is compressed, while the material behind it cools and contracts rapidly, creating a moving tensile stress peak behind the heat source.

[0036] To ensure the stability and repeatability of crack propagation, this method also introduces a "preheating-main heating" synergistic loading strategy. Before the formal fragmentation scan (main heating), the path is first rapidly pre-scanned (preheated) once or several times with a low-power (e.g., 5-10W) CO2 laser beam. This step can eliminate any internal residual stress inhomogeneities that may exist in the material itself due to manufacturing or storage processes, creating a uniform and consistent stress "base" for subsequent main heating fragmentation.

[0037] After preheating, the higher peak tensile stress field generated by the main thermal scan acts on the weakest guide line pre-fabricated by the picosecond laser, precisely determining the crack initiation point and propagation path. This ensures that the crack can stably and controllably penetrate the entire substrate thickness along the preset path in one go, achieving precise separation of the lens blank.

[0038] The synergistic effect of the two-step method overcomes the inherent limitations of a single process. The first step, the "cold processing" of the picosecond laser, ensures ultra-high precision and "non-destructive" characteristics of the guiding path, while the second step, the "thermal guidance" of the CO2 laser, provides a global, flexible force sufficient to drive crack propagation. The resulting cut surface exhibits low surface roughness; for example, under a scanning electron microscope, the size and number of defects such as conchoidal fractures and secondary cracks are significantly reduced compared to traditional cutting methods. This fundamentally improves the edge quality and mechanical strength of the PVG lens, laying a solid foundation for the high reliability of subsequent products.

[0039] Example 2

[0040] This embodiment is basically the same as embodiment 1, except that in this embodiment, the PVG lens blank 1 is a composite stacked structure. This embodiment mainly describes the technical logic of the composite stacked structure design and its integrated manufacturing process.

[0041] A. Design principles and diversity of PVG lens composite structures

[0042] First, the fundamental reason for adopting a composite structure design for PVG lenses is explained. The core optical function of the polarizer holographic grating is carried by its internal PVG functional film layer 14, which is typically composed of organic materials such as oriented liquid crystal polymers. The inherent physical properties of such materials determine their low mechanical strength and extreme sensitivity to changes in humidity and temperature in the environment. If this functional film layer 14 is directly exposed to the external environment, it will not only be unable to withstand the physical stress during processing and use, but its optical performance (such as diffraction efficiency and polarization contrast) will also rapidly degrade due to environmental corrosion, which fundamentally limits its reliability and lifespan in high-performance applications.

[0043] To overcome the aforementioned bottlenecks, this application employs a "sandwich" type composite packaging structure. This structure permanently encapsulates the fragile functional film layer 14 between two robust optical substrates 12 by laminating a first sheet 10 with the functional film layer 14 onto a second sheet 20. In this structure, the outer substrate 12 provides rigid mechanical support and macroscopic isolation from the environment, while the inner functional film layer 14 focuses on achieving its preset light field modulation function. Therefore, constructing the preform of this composite structure is fundamental to achieving the mechanical stability and environmental tolerance of the final product.

[0044] Based on this composite structure platform, design variations that meet different application requirements can be derived:

[0045] The first variant is a highly efficient diffraction structure for processing unpolarized light:

[0046] For applications using natural light or unpolarized light sources, an additional optical element, such as a half-wave plate, can be laminated between two identical PVG functional film layers 14.

[0047] Its working principle is as follows: the first polarization component of the incident light that meets the diffraction conditions of the first PVG grating is diffracted; the second polarization component, which is orthogonally transmitted, rotates 90 degrees in polarization direction after passing through the half-wave plate, thereby satisfying the diffraction conditions of the second PVG grating and being diffracted.

[0048] The second variant is a multi-wavelength optimized structure for full-color displays:

[0049] In AR / VR full-color display applications, the first functional film layer 14 can be designed as a grating with high diffraction efficiency for the red and blue light bands, while the second functional film layer 14 can be designed as a grating with high diffraction efficiency for the green light band. After lamination, different colors of light are diffracted by their respective optimized gratings, effectively solving the technical problem that a single grating cannot simultaneously achieve high diffraction efficiency across the entire visible light range.

[0050] Highly integrated structures for waveguide displays:

[0051] In such applications, the first and second functional layers 14 are designed as a functionally complementary optical waveguide coupling system. For example, the first functional layer 14 acts as an input grating, diffracting a light beam from the microdisplay into the substrate 12 at an angle that satisfies total internal reflection (TIR); simultaneously, the second functional layer 14 acts as an output grating, diffracting the light beam out of the substrate 12 when it reaches the field of view of the human eye. This functionally separated design allows for independent optimization and fabrication of the parameters of the input and output gratings (such as period, tilt angle, and efficiency spatial distribution), significantly simplifying the process complexity.

[0052] Therefore, in this embodiment, the functional film layer 14 of the first sheet 10 is designed to have high diffraction efficiency for light in the first wavelength range, while the functional film layer 14 of the second sheet 20 is designed to have high diffraction efficiency for light in the second wavelength range, and the first wavelength range is different from the second wavelength range.

[0053] The core effect of this technology is that it achieves highly efficient full-color augmented reality display while maintaining the lens's thinness and transparency through "wavelength channel separation." It cleverly stacks multiple functional films targeting different narrowband spectra. Each film acts as a precise "color router," efficiently diffracting only the color it's responsible for (such as green light) and projecting it into the user's eyes, while remaining completely transparent to other colors and ambient light. This "divide and conquer" design not only avoids the bulkiness and light loss of traditional color combining schemes but also ensures that each color channel operates at peak efficiency, allowing users to clearly see the real world while also viewing bright and realistic full-color virtual images.

[0054] For example, the light in the first wavelength range can be designed to cover the core region of the green spectrum, such as 520 nanometers to 540 nanometers.

[0055] The light in the second wavelength range can be designed to cover the core region of the red spectrum, for example, from 620 nanometers to 640 nanometers.

[0056] B. Manufacturing process of high-reliability PVG lens blanks

[0057] Based on the aforementioned requirements for composite structures, this embodiment discloses a precision method for manufacturing a high-reliability blank with an integrated edge seal. This method specifically includes the following interrelated sub-steps:

[0058] Step B1): Selective "cold" removal of the edge functional membrane layer

[0059] The purpose of this step is to eliminate the inherent defects of traditional organic adhesive sealants (such as air permeability and aging problems) and construct a physically continuous inorganic seal boundary composed of the substrate material itself.

[0060] Before laminating the first sheet 10 and the second sheet 20, they are pretreated. Preferably, a third laser 33 is used, namely an ultraviolet (UV) picosecond laser with an output wavelength of 355 nanometers. The ultraviolet band is chosen because most organic functional film layers 14 have strong intrinsic absorption in this band; the picosecond-level ultrashort pulse width is chosen to trigger the "cold ablation" mechanism, that is, the material directly photochemically decomposes and vaporizes after absorbing energy, with almost no heat conduction, thereby avoiding any thermal damage or residual stress to the adjacent glass substrate 12.

[0061] The third laser beam precisely ablates a ring-shaped functional film layer 14 with a width of 1.0-2.0 mm (1.5 mm in this example) at a specific distance (e.g., 1.0 mm) from the physical edge of the sheet. The value of this step is that it creates an inorganic contact interface free of organic residue for subsequent direct bonding without damaging the substrate.

[0062] Step B2): Precision alignment and vacuum thermoforming bonding

[0063] After undergoing the "film removal" process, the first sheet 10 and the second sheet 20 (e.g., Schott D263T optical glass with a thickness of 0.5 mm) are fed into a vacuum lamination system integrating visual recognition and precision motion control. The system captures pre-set alignment reference marks on the sheets using a high-resolution CCD camera, and image processing algorithms calculate the translational and rotational errors between the two in real time. The central controller then drives a six-axis precision parallel robot to perform attitude compensation with sub-micron resolution until the preset alignment accuracy (e.g., alignment tolerance < 2 μm) is achieved.

[0064] After alignment, the laminating mechanism applies uniform pressure (e.g., 0.3-1.0 MPa) and a suitable temperature (e.g., 60-100°C) to the two sheets in a vacuum environment (< 10⁻³ Pa) to perform vacuum thermocompression bonding.

[0065] In this embodiment, the peripheral sealing strip 16 is formed based on the microscopic elastic deformation and direct bonding principle of the substrate 12. Specifically, before laminating the first sheet 10 and the second sheet 20, the functional film layer (14) in their respective edge regions is selectively removed by laser. This results in the central region being supported by the functional film layer 14 after lamination and alignment, while the edge regions leave a tiny gap between the two substrates 12 with a height equal to the sum of the thicknesses of the two functional film layers. In the subsequent vacuum hot pressing step, the uniform pressure applied to the surface of the substrate 12 causes the unsupported edge regions to undergo micron-level elastic bending deformation, thereby completely closing the gap and enabling the clean surfaces of the two substrates 12 to achieve physical close contact within the annular region. Under continuous pressure and temperature, the intermolecular forces (such as van der Waals forces) at the contact interface promote the formation of a strong, physically continuous inorganic bond, thus forming an integrated peripheral sealing strip 16. This process utilizes the inherent elasticity of the thin substrate to cleverly overcome the gap problem caused by the thickness of the functional film layer, achieving airtightness and long-term reliability far superior to traditional organic adhesive seals.

[0066] C. Optimization of cutting process: integrated synchronous cutting

[0067] After obtaining the high-quality PVG lens blank 1, this embodiment further optimizes the cutting steps described in Example 1 in order to overcome potential stress relaxation effects and maximize production efficiency.

[0068] Specifically, steps b) "picosecond laser constructing the guide path" and c) "CO2 laser applying thermal stress" in Example 1 are integrated into a single, dual-wavelength synchronous scanning process. In the optical system design, the 532nm green picosecond laser beam used for step b) and the 10.6μm CO2 laser beam used for step c) are coaxially combined using a dichroic mirror that is highly transparent to green light and highly reflective of long-wave infrared light. The combined dual-color laser is driven by the same set of scanning galvanometers 5, ensuring spatial overlap of the two lasers along the processing path.

[0069] The central control system 6 is programmed to precisely coordinate the emission timing of the two lasers. Its core principle is that at any point along the scanning path, after the ultrafast pulse train of the picosecond laser completes the construction of the microscopic guide groove, the heated spot of the CO2 laser immediately follows within an extremely short threshold time window (e.g., 1-100 microseconds). This preset threshold can be determined experimentally, and its upper limit depends on the thermophysical properties (such as thermal diffusivity) and thickness of the specific substrate material, ensuring that the stress concentration effect formed by the first wavelength laser has not significantly attenuated under thermal stress.

[0070] This solution relates to a laser cutting technology that synchronously controls two lasers, one of which forms an initial microcrack on the material surface. Because this microcrack has a sharp geometric tip, it constitutes a stress concentration point. Therefore, the thermal stress field generated by the other CO2 laser preferentially and concentratedly acts on the tip of this microcrack. This stress concentration provides the driving force for the directional propagation of the crack, causing it to extend vertically along a predetermined path, while suppressing the generation of random cracks. This method achieves a smooth cut surface with no chipped edges, and simplifies the process and improves processing efficiency through an integrated design.

[0071] This simultaneous 'scratch and heat' mechanism avoids the internal stress relaxation effect that may be caused by the time delay of step-by-step operation, ensuring that the thermal stress field generated by the CO2 laser can act on the most vulnerable, newly formed stress concentration line of the structure with maximum efficiency. This not only reduces the total energy threshold required for cracking, but also significantly improves the stability and controllability of crack propagation, achieving a synergistic enhancement of process effects.

[0072] Example 3

[0073] This embodiment proposes an optimized scheme to further improve energy coupling efficiency and focusing accuracy in the laser cutting steps of Embodiments 1 and 2, namely, by using an auxiliary optical medium 18. This scheme solves the problems of approximately 4% Fresnel reflection energy loss caused by the approximately 1.5 refractive index difference between air (n≈1.0) and glass substrate 12 (n≈1.5) when the laser beam (especially the first wavelength laser forming the stress concentration line) enters the lens blank, as well as possible spherical aberration and focus point offset issues.

[0074] Before performing cutting step b), this embodiment adds the following step: a removable auxiliary optical medium 18 is placed on the surface to be processed of the PVG lens blank 1.

[0075] As one specific implementation, the auxiliary optical medium 18 is a pre-fabricated composite optical layer. The layer structure includes a transparent substrate layer 180, a solid optical adhesive layer 182, and a release film (not shown).

[0076] The transparent substrate 180 is a 100μm thick PET (polyethylene terephthalate) film with a hardened surface, which has good scratch resistance.

[0077] The solid optical adhesive layer 182 is an acrylic optical adhesive with a thickness of 25 μm. Its refractive index after curing is precisely designed to be 1.51, which is highly matched with the refractive index (1.52) of the glass substrate 12.

[0078] Release film is a silicone-coated PET film that protects the OCA adhesive layer.

[0079] Operating procedure: Before cutting, the auxiliary optical medium 18 is laminated onto the upper surface of the PVG lens blank 1 smoothly and without bubbles using a roller laminator in a Class 1 cleanroom environment.

[0080] When the first wavelength (532nm) laser beam is incident from above, its propagation path is as follows: it first passes through the transparent substrate layer 180 of the auxiliary optical medium 18, and then through the solid optical adhesive layer 182. Because the refractive index of the solid optical adhesive layer 182 (e.g., 1.51) is highly matched with the upper substrate 12 of the PVG lens blank 1 (e.g., glass with a refractive index of 1.52), Fresnel reflection of the laser beam at this critical interface between the solid optical adhesive layer 182 and the substrate 12 is greatly suppressed, increasing the energy coupling efficiency from approximately 96% to nearly 100%. More importantly, this refractive index matching eliminates focus drift and spherical aberration introduced by interface refraction, ensuring that the laser energy can be precisely and stably focused at a predetermined depth within the upper substrate 12, thereby forming a high-quality stress concentration line.

[0081] After cutting, the adhesive layer can be easily peeled off without leaving any adhesive residue. The auxiliary optical medium 18 is ultimately used to achieve bonding and optical coupling between the composite optical adhesive layer and the PVG lens blank 1.

[0082] The core technological value of this auxiliary optical medium lies in its fundamental solution to a series of physical problems caused by significant refractive index mismatch (e.g., n≈1.0 vs n≈1.5) at the air-substrate interface for the first-wavelength laser beam. Specifically, refractive index mismatch first leads to Fresnel reflection energy loss; more importantly, the refraction of the beam at the interface introduces a focal depth shift related to the incident angle (i.e., "focal drift"), and significantly exacerbates the inherent spherical aberration of the optical system, resulting in dispersed and unreliable focal energy. By employing an auxiliary optical medium with a refractive index precisely matched to the substrate, the original air-substrate high-mismatch interface is replaced by an optically nearly continuous medium-substrate matched interface. At this new interface, due to the refractive index matching, the refraction effect of the beam is eliminated from a physical perspective. This not only increases the energy coupling efficiency to nearly 100%, but more importantly, it completely suppresses focal drift and spherical aberration deterioration. The ultimate goal is to ensure that laser energy can be focused into the substrate with a smaller, higher energy density, and more stable depth position. This is the physical prerequisite and reliable guarantee for forming uniform, precise, and high-quality stress concentration lines.

[0083] Example 4

[0084] This embodiment discloses an automated polarizer holographic grating (PVG) manufacturing system for performing the methods disclosed in any of the foregoing embodiments. This system integrates complex manufacturing processes onto a single platform through highly integrated functional modules and unified central control, aiming to achieve a high degree of automation, high precision, and high efficiency in the PVG lens manufacturing process.

[0085] Please see Figure 1 The manufacturing system mainly consists of a worktable 2, a laser system 3, an optical system 4, a scanning galvanometer 5, and a central control system 6 in terms of physical structure.

[0086] Specifically, the worktable 2 is used to precisely clamp and position the PVG lens blank 1 to be processed. The worktable 2 can be an air-bearing platform or a servo motor-driven platform with X, Y, and Z axis precision displacement functions, and its bearing surface defines a unified coordinate reference for the entire processing. In this embodiment, the worktable 2 includes a bearing platform 21 and a clamping mechanism 23, which fixes the PVG lens blank 1 from all sides.

[0087] The laser system 3 is the core energy source for performing the processing. It includes a first-wavelength laser 31 (such as a picosecond or femtosecond laser) for forming stress concentration lines, a second-wavelength laser 32 (such as a carbon dioxide laser) for applying thermal stress loading, and optionally, a third-wavelength laser 33 for surface treatment. The output states of the two lasers (such as power, frequency, switching, etc.) are controlled by the central control system 6.

[0088] Optical system 4 is responsible for guiding, combining, and focusing the two laser beams emitted by laser system 3. In a preferred embodiment, optical system 4 includes a series of mirrors, a beam expander forming a shaping lens 41, and one or more dichroic mirrors 42. For example, a specific dichroic mirror 42 is configured to efficiently transmit the first wavelength laser beam while efficiently reflecting the second wavelength laser beam, thereby precisely combining the two laser beams into a coaxially propagating composite laser beam. Subsequently, this composite laser beam is focused onto the surface or interior of the lens blank on stage 2 through a flat-field scanning lens (f-theta lens).

[0089] The scanning galvanometer 5 is located downstream of the optical path of the optical system 4. It consists of two high-speed rotating miniature mirrors (X-mirror and Y-mirror). Under the command of the central control system 6, the scanning galvanometer 5 performs two-dimensional scanning deflection on the incident composite laser beam, thereby driving the focused laser spot to draw the preset cutting path on the lens blank at high speed and with precision.

[0090] The central control system 6 consists of an industrial computer and supporting hardware such as motion control cards and I / O control cards, and runs dedicated control software. This system is pre-configured and programmed, storing a complete machining program including cutting paths (usually from CAD files), laser parameters, and scanning speed. During task execution, the central control system 6, according to the programmed timing sequence, uniformly schedules and coordinates the movement of the worktable 2, the light emission of the laser system 3, and the deflection of the scanning galvanometer 5, thereby automatically and continuously executing any of the manufacturing method steps defined in embodiments 1 to 3 above.

[0091] As a further configuration, the manufacturing system can also integrate a vision alignment subsystem 7 and an automated lamination mechanism 8. The vision alignment subsystem 7 (e.g., a high-resolution CCD camera) is used to capture alignment reference marks on the sheet before lamination; the automated lamination mechanism 8 (e.g., a hot press) is used to perform the lamination operation. For example, in this embodiment, to achieve precise positioning, the automated lamination mechanism 8 can be driven to move as a whole by a three-axis motion mechanism 81. In this configuration, the central control system 6 is also configured to process image data from the vision system, calculate alignment errors, and control the worktable 2 or a dedicated alignment platform for correction, ultimately driving the lamination mechanism to complete high-precision alignment lamination.

[0092] By deeply integrating hardware such as laser source, optical path, scanning mechanism, motion platform and optional alignment and lamination module under the unified scheduling of central control system 6, the automated manufacturing system of this embodiment overcomes the problems of cumulative error and low efficiency caused by multiple clamping and alignment in traditional substation processing, thus providing a solid and reliable equipment guarantee for the large-scale, high-precision and fully automated production of high-quality PVG lenses.

[0093] Example 5

[0094] This embodiment discloses a polarizing holographic grating (PVG) lens product. This product fundamentally solves the core technical problems of traditional PVG lenses, such as the susceptibility of the functional coating layer to environmental corrosion and the low mechanical strength of the lens edge.

[0095] Please see the appendix Figure 2 The specific structural features of this PVG lens product include the following interrelated parts, which are defined by a specific process:

[0096] First, there is the composite lens body, which is the core of the product. This body is formed by laminating and sealing the middle PVG functional film layer 14 between two transparent substrates 12. The transparent substrates 12 can be optical materials such as quartz glass or borosilicate glass, and the PVG functional film layer 14 is an environmentally sensitive optical polymer.

[0097] Secondly, there is the integrally formed sealing strip 16 located around the lens. This sealing strip 16 is not formed by external adhesive or sealant applied later, but is an inherent structure formed through the "laser pre-film removal followed by alignment lamination" process described in the previous embodiment. In this process, a laser (e.g., an ultraviolet picosecond laser) precisely and selectively removes the annular region of the edge of the PVG functional film layer 14 before lamination. Subsequently, under high temperature and pressure, the upper and lower substrates 12 achieve direct molecular-level close contact within this annular region, forming a complete inorganic material sealing ring.

[0098] It replaces traditional organic polymer sealants with inorganic materials (glass) from the substrate itself. As is well known to those skilled in the art, organic adhesives inherently possess a certain degree of air and moisture permeability, and their bonding interface with the glass substrate is a weak channel for water vapor penetration, making them prone to aging and failure under high temperature and humidity conditions. This solution, however, forms a physically continuous and chemically stable airtight seal through direct contact between the substrates. This sealing surface is essentially a dense glass, whose ability to block water vapor and gases is physically far superior to any polymer. Therefore, this integrated sealing tape provides a superior, durable, and reliable hermetic seal, effectively ensuring that the optical performance of the internal functional film layer remains stable even after long-term use or exposure to harsh environments (such as high temperature and humidity).

[0099] Furthermore, the lens cutting surface possesses nanoscale surface roughness. This is the second key structural feature enabling the product to achieve high mechanical strength. The microscopic morphology of this surface is smooth and flat, and under high-magnification microscopy such as scanning electron microscopy (SEM), no randomly distributed microcracks, common in traditional cutting methods, are observed.

[0100] This superior cross-sectional characteristic is an inevitable result of the combination of the "picosecond laser helical circumferential cutting pre-formed stress-guided groove" and the "carbon dioxide laser thermal stress-guided cleavage" method described in the aforementioned embodiments. Since the crack propagates smoothly in one go along a pre-set, microscopically extremely uniform and continuous stress concentration line within the material, driven by a highly uniform and controllable thermal stress field, its fracture surface is essentially a pure cleavage surface, rather than a violent fracture surface of the material. According to Griffith's microcrack theory in materials mechanics, the macroscopic strength of a material depends on the size of its largest surface defect. The cross-section formed by this method fundamentally eliminates microcrack defects that act as stress concentration sources. Therefore, it is reasonable to expect that, compared to mechanical scribing cutting with numerous random microcracks or laser ablation cutting with heat-affected zones, the inherent mechanical strength and fracture resistance of the product's edges will be significantly improved.

[0101] In summary, the PVG lens product of this embodiment achieves a synergistically enhanced overall technical effect through its unique structural combination determined by a specific manufacturing method. The integrated sealing strip 16, formed by the "laser pre-coating removal" process, solves the core survival problem of moisture and airtightness of the functional coating layer from the inside of the lens; the smooth cut surface formed by the "dual laser-guided dicing" process solves the problems of mechanical strength and reliability from the lens edge; and the optional cross-section passivation protection layer further enhances its long-term reliability in extreme application scenarios.

[0102] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for manufacturing a polarizing holographic grating (PVG) lens, characterized in that, include: a) Provide a PVG lens blank (1), the PVG lens blank (1) including at least one substrate (12) and a functional film layer (14) disposed thereon; b) Contour engraving step: On the PVG lens blank (1), a first wavelength laser beam is used to scan along a preset cutting path to form a stress concentration line; c) Guided cracking step: Using a second wavelength laser beam to scan along the same cutting path, thermal stress is applied to the stress concentration line to guide the crack to propagate from the stress concentration line, thereby separating the PVG lens blank (1) along the cutting path.

2. The method according to claim 1, characterized in that, Prior to step b), the PVG lens blank (1) is formed by the following alignment lamination steps: i. Provide a first sheet (10) and a second sheet (20), each sheet comprising a substrate (12) and a functional film layer (14); ii. Form machine vision-recognizable alignment reference marks on the first sheet (10) and the second sheet (20), respectively; iii. Based on the alignment reference mark, the first sheet (10) and the second sheet (20) are aligned and laminated with their functional film layers (14) facing each other using a visual alignment system to form the PVG lens blank (1).

3. The method according to claim 1, characterized in that, Steps b) and c) are integrated into a single synchronous scanning process, wherein: The spot of the first wavelength laser beam and the spot of the second wavelength laser beam are coaxial in space or arranged at a fixed interval, and are driven by the same scanning galvanometer (5) to scan synchronously along the preset cutting path; Furthermore, at any point on the scanning path, the time interval between the formation of the stress concentration line and the application of thermal stress to it is controlled within a preset threshold.

4. The method according to claim 1, characterized in that, In the contouring step, the scanning of the first wavelength laser beam includes: causing the focal point of the first wavelength laser beam to move in a high-speed spiral or circular motion with a preset small radius, while the geometric center of the spiral or circular motion moves along the preset cutting path.

5. The method according to claim 2, characterized in that, Prior to the alignment lamination step iii), the method further includes selectively removing the functional film layer (14) in a predetermined edge region of the first sheet (10) and / or the second sheet (20), such that after lamination, the two substrates (12) are in direct contact in the predetermined edge region to form a peripheral sealing strip (16).

6. The method according to claim 1, characterized in that, Before performing step b), the method further includes the following steps: A removable auxiliary optical medium (18) is provided on the surface to be processed of the PVG lens blank (1). The auxiliary optical medium (18) has a preset thickness, its refractive index matches that of the PVG lens blank (1), and it is transparent to the first wavelength laser beam. This is used to form an optical coupling interface between the PVG lens blank (1) and the auxiliary optical medium (18) and to provide a transparent path for the first wavelength laser beam.

7. The method according to claim 6, characterized in that, The auxiliary optical medium (18) includes: A transparent substrate (180); and A solid optical adhesive layer (182) is disposed between the transparent substrate layer (180) and the PVG lens blank (1).

8. A polarizing holographic grating manufacturing system, characterized in that, include: A worktable (2) for holding PVG lens blanks (1); A laser system comprising a first wavelength laser and a second wavelength laser (3); An optical system (4) that guides and focuses the first wavelength laser beam and the second wavelength laser beam onto the PVG lens blank (1); A scanning galvanometer (5) for driving a laser beam to scan along a preset cutting path; and A central control system (6) is configured to perform the method steps as defined in any one of claims 1 to 7.

9. The system according to claim 8, characterized in that, The system further includes a visual alignment subsystem (7) and an automatic lamination mechanism (8); wherein the central control system (6) is further configured to: when performing the alignment and lamination step, based on the position information of the alignment reference mark obtained by the visual alignment subsystem (7), control the first sheet (10) and the second sheet (20) to align, and drive the automatic lamination mechanism (8) to complete the lamination.

10. A polarizing holographic grating (PVG) lens, characterized in that, include: Two substrates (12) are arranged opposite each other; A functional film layer (14) is sandwiched between two substrates (12), and at the edge of the functional film layer (14), there is a peripheral sealing strip (16) that surrounds and seals the functional film layer (14).

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