Preparation method of micro-prism and black AR composite optical cover plate for aerial imaging

Abstract

The application discloses a preparation method of a micro-prism and black AR composite optical cover plate for aerial imaging, and belongs to the field of aerial imaging optical glass processing technology. The method sequentially completes the following steps: precision machining of a base material, one-way micro-prism nano-imprinting of an inner side to adapt to an oblique incidence light path, vacuum coating of an inner side anti-reflection film, sputtering of an outer side multi-layer dielectric interference extinction black AR film, and finished product optical and weather resistance detection and packaging. The prepared optical cover plate is assembled above a flat plate lens, and the inner side adhering surface can be closely adhered to the flat plate lens or a reserved assembly interval of an adapted light path. The micro-prism optical structure formed by nano-imprinting has multiple light field regulation functions: guaranteeing high transmission of oblique imaging light; achieving light shielding by total internal reflection of external vertical ambient light; performing angle pre-compensation on the flat plate lens outgoing light to correct imaging distortion; and widening the viewing angle by diverging the edge light beam. Inorganic vacuum coating technology is adopted throughout the process, there is no organic ink and no metal light absorption layer, and the finished product is suitable for vehicle-mounted, household consumer and commercial display all-in-one medium-free aerial imaging equipment with a flat plate lens, and the prepared cover plate outer visible surface presents a pure black visual effect.

Description

Technical Field

[0001] This invention belongs to the field of optical glass processing technology for non-medium aerial imaging. The optical cover plate prepared is compatible with all aerial imaging devices equipped with flat lens, covering multiple application scenarios such as automotive, home consumer, and commercial holographic display. Background Technology

[0002] The current mainstream manufacturing process for black light-shielding optical covers with flat lenses and displays underneath has significant shortcomings: The blackening process of screen printing with black ink relies on the absorption of light by black ink to achieve a black appearance. The light transmittance of the finished product is much lower than 90%, which cannot meet the requirements of high light transmittance imaging. The ink is prone to cracking, peeling, and discoloration in high-temperature environments. There is no distortion correction or widening of the viewing angle matching light field control structure. Unidirectional metal coating process: sputtering aluminum and chromium metal layers to achieve unidirectional light blocking and black appearance. The metal coating continuously absorbs imaging light, and the upper limit of light transmission is low. Under strong light, it produces mirror ghosting that interferes with the imaging image. When the internal brightness is higher than the external brightness, perspective reversal occurs. It has no function to optimize the imaging image and viewing angle. Ordinary microprism imprinting process: The microprism lacks an angle matching design to adapt to the oblique incident light path, and only has the function of beam convergence and privacy protection. The oblique imaging light loss is serious, the dark corner of the image is obvious, and it cannot correct the distortion caused by the flat lens or widen the viewing window. Without the matching multi-layer dielectric interference matte black AR coating, the cover plate's visible window is transparent and bright, and it cannot achieve the appearance effect of an integrated pure black window.

[0003] For a long time, it has been widely believed in the field that there is a fundamental contradiction between the "pure black appearance for light blocking" and the "high transmission of imaging light" of aerial imaging cover plates, and that light blocking inevitably comes at the cost of light transmittance. Therefore, existing processing technologies either choose to sacrifice appearance for light transmission or sacrifice light transmission for appearance, and no optical cover plate manufacturing method has been found that can simultaneously satisfy multiple functions such as high light transmittance, pure black appearance, texture masking, distortion correction, and wide viewing angle through the same set of process solutions.

[0004] To address this, the present invention proposes a method for preparing a microprism and a black AR composite optical cover plate for aerial imaging. By combining customized microprism nanoimprinting with a double-sided sequential vacuum coating process, multiple technical problems are solved simultaneously, including high light transmittance imaging, permanent masking of flat lens texture, pure black appearance, hardware correction of imaging distortion, and widening of viewing angle. Summary of the Invention

[0005] Purpose of the invention We provide a universal optical cover plate manufacturing process that eliminates the need for a single fixed processing parameter. Within a reasonable parameter range, we can stably produce optical cover plates that simultaneously meet the requirements of high light transmittance, permanent concealment of micro-nano textures in flat lens, pure black outer surface, hardware correction of imaging distortion, widened viewing angle, and resistance to environmental aging. This solves the manufacturing defects of existing processes, such as insufficient light transmittance, poor texture concealment, uneven blackening of appearance, lack of imaging optimization function, limited applicable scenarios, and easy failure after long-term use. Technical solution

[0006] A method for fabricating a microprism and black AR composite optical cover plate for aerial imaging includes the following processing steps: S1. Precision processing of substrate: Select optical glass raw materials, and complete precision cutting, double-sided precision grinding, and four-sided polishing and chamfering in sequence. Then, temper the glass to ensure high flatness and optical uniformity. S2. Inner Microstructure Forming: A UV imprinting adhesive is coated on the inner bonding surface of the glass, and a unidirectional microprism optical structure is formed using a nanoimprinting process. The unidirectional microprism optical structure has the following light field modulation function: (1) Maintain high transmission for imaging rays incident at an oblique angle; (2) Total internal reflection of ambient light incident perpendicularly from the outside is used to achieve shading; (3) Perform angle pre-compensation on the imaging light rays emitted through the flat lens to correct the geometric distortion of the image; (4) Expand the beam outward from the edge of the field of view to broaden the effective viewing angle; After molding, plasma cleaning is used to remove residual adhesive residue from the surface. S3, Inner Anti-reflection Coating: The glass with the completed microstructure is fed into a vacuum magnetron sputtering device to deposit an anti-reflection coating on the surface of the microprism optical structure to reduce the reflection loss of the oblique imaging light interface. S4. External matte black coating: Flip the glass and use a high-vacuum magnetron sputtering process to alternately deposit high and low refractive index inorganic dielectric films on the visible surface of the glass to form a multilayer dielectric interference matte black AR anti-reflection coating. S5. Finished Product Inspection and Packaging: The coated glass is ultrasonically cleaned and dried in a dust-free environment. Optical performance testing and weather resistance testing are carried out in sequence. After passing the tests, the glass is packaged with a dust-free protective film and shipped.

[0007] The optical cover plate prepared by this method is placed above the flat lens when the whole machine is used. The inner bonding surface of the cover plate is parallel and opposite to the flat lens. The two can be tightly fitted together, or an assembly gap can be reserved to adapt to the optical path.

[0008] Beneficial effects The microprism structure has four light field modulation functions: high transmission, total internal reflection shading, distortion correction, and widening of viewing angle. One structure can solve multiple technical problems simultaneously. The double-sided sequential vacuum coating structure features anti-reflection and anti-reflection coating on the inner side and matte black coating on the outer side, with no metal or organic light-absorbing inks throughout the entire process. A dual-standard weather resistance testing system allows for the simultaneous production of two types of finished products: automotive and consumer / commercial products using the same manufacturing process. The entire process of inorganic vacuum coating results in strong film adhesion, and there is no film peeling, whitening, or fading even after long-term use at high and low temperatures or room temperature. It has strong process compatibility; a universal master template can be used for small-batch samples, and high consistency is achieved in large-scale mass production. Attached Figure Description

[0009] Figure 1 This is a flowchart illustrating the complete fabrication process of the composite optical cover plate for aerial imaging according to the present invention. Detailed Implementation

[0010] Example 1 (Standard manufacturing process for vehicle-mounted adapter cover) S1. Substrate processing: 2mm low-iron ultra-white glass is cut and shaped, double-sided grinding TTV 0.002mm, chemically tempered with potassium nitrate molten salt at 420℃ for 4.5h, and then cleaned and cooled. S2, Inner Microstructure Imprinting: A 90μm period, 40° tilt angle microprism metal master plate is selected, and a 365nm UV curing energy of 900mJ / cm² is used to form a microprism array. Plasma cleaning is used to remove residual adhesive. The formed microprism can control the light emitted from the flat lens in four ways: high transmission of oblique imaging light, total internal reflection of vertical ambient light, distortion correction, and edge beam expansion. S3, Inner side vacuum sputtered single-layer SiO2 antireflection film; S4. TiO2 and SiO2 media are alternately deposited in a high vacuum chamber, and 12 layers of matte black AR film are continuously sputtered. S5. Ultrasonic cleaning and drying, full inspection of optical performance, sampling to perform 500 cycles of cold and hot cycling weathering test from -40℃ to 85℃, and dust-free packaging after passing the test.

[0011] Finished product test results: oblique light transmission 91.2%, frontal reflection 0.26%, no flat lens texture observed at 30cm, distortion 0.92%, horizontal viewing angle improvement 31.8%, no defects in high and low temperature cycle tests.

[0012] Example 2 (Preparation process of consumer and commercial adapter cover) The substrate, microprism structure, and coating process are completely consistent with those in Example 1. The microprism tilt angle is 39° and the period is 88μm. 11 layers of matte black AR film are deposited on the outer side. The post-processing step cancels the 500-cycle high and low temperature cycle and replaces it with continuous aging and sampling inspection at room temperature for 1000 hours. The optical, distortion, and viewing angle indicators of the finished product are consistent with those in Example 1. There is no degradation in appearance or optical performance during long-term indoor use.

[0013] Comparative Example 1 (the inner microprism nanoimprinting process is omitted) The remaining processing steps are exactly the same, and there is no microprism optical structure on the inside of the glass; the finished product has 84.7% oblique light transmission, the texture of the flat lens is clearly visible, and there is no distortion correction or widening of the viewing angle function, which cannot meet the usage requirements.

[0014] Comparative Example 2 (The microprism is not adapted to the oblique incident light path and adopts an 18° tilt angle) The remaining processes remain unchanged, but the microprism tilt angle is 18°; the light transmittance of oblique imaging is 83.1%, and obvious dark corners appear at the edges of the image, further narrowing the viewing angle.

[0015] This invention is not limited to the above embodiments and comparative examples. Any similar preparation process obtained by making conventional equivalent substitutions for the substrate specifications, microprism processing parameters, number of film layers, and weather resistance testing standards based on the process ideas disclosed in this invention falls within the protection scope of this invention.

[0016] Industrial applicability The method for preparing a composite optical cover plate for aerial imaging using microprisms and black AR provided by this invention can be applied to the mass production of various medium-free aerial imaging optical cover plates, such as cover plates for vehicle-mounted aerial imaging equipment, cover plates for home desktop holographic projectors, and cover plates for commercial holographic display cabinets. The entire process utilizes an inorganic vacuum coating process, resulting in high product consistency. A single production line can simultaneously produce cover plates for vehicle-mounted, home, and commercial applications, demonstrating significant industrial application value and market potential.

Claims

1. A method for fabricating a microprism and black AR composite optical cover plate for aerial imaging, characterized in that, It includes the following processing steps: S1. Precision processing of substrate: Select optical glass raw materials, and complete precision cutting, double-sided precision grinding, and four-sided polishing and chamfering in sequence. Then, temper the glass to ensure high flatness and optical uniformity. S2. Inner Microstructure Forming: A UV imprinting adhesive is coated on the inner bonding surface of the glass, and a unidirectional microprism optical structure is formed using a nanoimprinting process. The unidirectional microprism optical structure has the following light field modulation function: (1) Maintain high transmission for imaging rays incident at an oblique angle; (2) Total internal reflection of ambient light incident perpendicularly from the outside is used to achieve shading; (3) Perform angle pre-compensation on the imaging light rays emitted through the flat lens to correct the geometric distortion of the image; (4) Expand the beam outward from the edge of the field of view to broaden the effective viewing angle; After molding, plasma cleaning is used to remove residual adhesive residue from the surface. S3, Inner Anti-reflection Coating: The glass with the completed microstructure is fed into a vacuum magnetron sputtering device to deposit an anti-reflection coating on the surface of the microprism optical structure to reduce the reflection loss of the oblique imaging light interface. S4. External matte black coating: Flip the glass and use a high-vacuum magnetron sputtering process to alternately deposit high and low refractive index inorganic dielectric films on the visible surface of the glass to form a multilayer dielectric interference matte black AR anti-reflection coating. S5. Finished product inspection and packaging: The coated glass is ultrasonically cleaned and dried in a dust-free environment. Optical performance testing and weather resistance testing are carried out in sequence. After passing the tests, the glass is packaged with a dust-free protective film and shipped. The optical cover plate prepared by this method is placed above the flat lens, with its inner bonding surface facing the flat lens. The two are parallel and opposite to each other, allowing for tight fitting and assembly, or a pre-reserved assembly gap to adapt to the optical path. The finished product can achieve high-transmittance transmission of oblique imaging light, while isolating the micro-nano texture of the flat lens from the outside. The outer side of the cover plate has a pure black appearance, correcting imaging distortion and widening the effective viewing angle. The finished product is compatible with various medium-free aerial imaging devices equipped with a flat lens and a display below. The light is modulated by the flat lens to form a real image in the air.

2. The method for preparing the microprism and black AR composite optical cover plate for aerial imaging according to claim 1, characterized in that: In step S1, the tempering process uses potassium nitrate molten salt chemical tempering to improve the glass's impact resistance and temperature adaptability.

3. The method for preparing the microprism and black AR composite optical cover plate for aerial imaging according to claim 2, characterized in that: Step S1 uses low-iron ultra-clear glass with a thickness of 0.3-5.0mm. After grinding, the glass TTV flatness is ≤0.003mm. The chemical tempering molten salt temperature is 420℃, and the soaking time is 4.5h.

4. The method for preparing the microprism and black AR composite optical cover plate for aerial imaging according to claim 1, characterized in that: In step S2, the tilt angle of the unidirectional microprism formed by nanoimprinting ranges from 30° to 55°, the period of the microprism array ranges from 50μm to 200μm, the ultraviolet curing wavelength is 365nm, and the curing energy ranges from 800 to 1000mJ / cm².

5. The method for preparing the microprism and black AR composite optical cover plate for aerial imaging according to claim 1, characterized in that: Step S4: The vacuum level of the vacuum sputtering chamber shall not exceed 5 × 10⁻ 4 Pa, the total number of outer matte black AR film layers ranges from 10 to 14 layers, no aluminum or chromium metal targets are used throughout the sputtering process, and no metal light-absorbing layer is deposited.

6. The method for preparing the microprism and black AR composite optical cover plate for aerial imaging according to claim 1, characterized in that: The optical performance standards for the finished product in step S5 are as follows: oblique incident visible light transmittance ≥90%, average ambient light reflectance on the outer front side <0.3%, and complete shielding of the micro-nano texture of the flat lens at a 30cm observation distance; imaging distortion ≤1% after compensation by the cover plate, and the effective viewing angle is improved by more than 30% compared with the solution without the cover plate.

7. The method for preparing the microprism and black AR composite optical cover plate for aerial imaging according to claim 1, characterized in that: Step S5 weather resistance sampling inspection is divided into two sets of standards; the vehicle-mounted adapter finished products are subjected to a 500-cycle cold and hot cycle test at -40℃ to 85℃; the consumer and commercial adapter finished products are subjected to a 1000-hour continuous aging test at room temperature; the qualification criteria for both types of products are that the film layer has no peeling, fogging, or discoloration, and the light transmittance fluctuation is ≤1.5%.

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