A method for preparing an anti-reflective microlens array

Abstract

The present invention belongs to the field of glass hot pressing technology, and in particular relates to a method for preparing an anti-reflective microlens array. The method for preparing an anti-reflective microlens array includes the following steps: preparing glass, a first mold, a second mold, and a heating device with a heating chamber; preparing an anti-reflective layer, heating the glass to a first temperature in the heating chamber; using the first mold to hot-press an anti-reflective micro-nano structure on the surface of the glass to form an anti-reflective layer, and cooling the glass; preparing a microlens array layer, heating the glass to a second temperature in the heating chamber, and using the second mold to hot-press a microlens structure on the surface of the glass to form a microlens array layer, wherein the size of the anti-reflective micro-nano structure is smaller than that of the microlens structure; demolding, and taking out the processed glass. The present application can realize the processing of optical glass, and the processing process is simple, and has the characteristics of high forming accuracy, high resolution, and high consistency.

Description

Technical Field

[0001] The invention belongs to the technical field of glass hot pressing, and in particular relates to a method for preparing an anti-reflection microlens array. Background Art

[0002] Currently, microlens arrays are optical devices composed of a series of lens units with apertures in the micrometer and submillimeter scales arranged in a regular pattern. They can achieve functions such as imaging, light distribution, focusing, diffusion, collimation, and sensing, and play a vital role in applications such as liquid crystal displays, solar cells, laser beam splitters, optical fibers, microscopic imaging sensors, and stereoscopic imaging. Because their structural characteristics resemble those of insect compound eyes, they are also called compound-eye lenses. The resolution of a single lens unit is generally very low, making it inefficient for imaging. When thousands of these units are combined, microlens arrays offer unique capabilities unattainable by monocular lenses, such as an extremely large field of view, uniform resolution across the entire image, and high temporal resolution. Therefore, microlens arrays can quickly and efficiently locate and identify moving objects, and reconstruct the target's shape and contour in three dimensions, thus overcoming the challenges of existing monocular lenses. However, the surface reflection effect of microlens arrays causes some incident light to be reflected, compromising the device's light transmission efficiency and optical imaging quality.

[0003] To achieve large-scale, high-volume fabrication of micro-nanoarray structures, scholars in the business and research communities have proposed various advanced manufacturing technologies, including electron beam lithography, colloidal lithography, laser surface interference lithography, nanosphere lithography, UV embossing, and hot embossing. Each process has its own advantages and disadvantages. For example, while photolithography can achieve high structural precision, it suffers from long processing cycles, the inability to continuously process large areas, and the high cost and maintenance of equipment, making it difficult to meet the demands of mass-production and large-scale fabrication. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a method for preparing an anti-reflective microlens array, aiming to solve the problem of how to process optical glass.

[0005] To achieve the above objectives, the technical solution adopted in this application is:

[0006] Provided is a method for preparing an anti-reflective microlens array for processing glass, the method comprising the following steps:

[0007] preparing glass, a first mold, a second mold, and a heating device having a heating chamber;

[0008] The anti-reflection layer is prepared by heating the glass to a first temperature in the heating chamber; using a first mold to hot-emboss an anti-reflection micro-nano structure on the surface of the glass to form the anti-reflection layer, and cooling the glass;

[0009] preparing a microlens array layer by heating the glass to a second temperature in the heating chamber and using a second mold to hot-emboss a microlens structure on the surface of the glass to form the microlens array layer, wherein the anti-reflective micro-nanostructure and the microlens structure are located on the same surface of the glass, the anti-reflective micro-nanostructure is smaller than the microlens structure, and the anti-reflective micro-nanostructure is arranged on the microlens structure;

[0010] Demoulding and taking out the processed glass.

[0011] In some embodiments, the first temperature is greater than the second temperature.

[0012] In some embodiments, the first mold includes a first molding head and a micro-nano template for placing the glass, and the micro-nano template is provided with an anti-reflective micro-nano structure; in the step of preparing the anti-reflective layer, the first molding head presses the glass toward the micro-nano template so that the glass replicates the anti-reflective micro-nano structure.

[0013] In some embodiments, the preparation of the anti-reflection layer comprises the following steps:

[0014] S21: evacuating the heating chamber, filling the heating chamber with nitrogen, evacuating the chamber again, and then filling the heating chamber with an inert gas;

[0015] S22: positioning the first mold in the heating chamber and placing the glass into the first mold, heating the glass to the first temperature;

[0016] S23: applying a first pressure to the glass by the first mold to form the anti-reflective micro-nano structure on the glass by hot pressing;

[0017] S24: Maintaining pressure on the first mold for a predetermined time and cooling the glass.

[0018] In some embodiments, the micro-nano structure includes a plurality of anti-reflective protrusions arranged at intervals.

[0019] In some embodiments, the cross-sectional shape of the anti-reflective protrusion is circular, elliptical, or polygonal.

[0020] In some embodiments, the second mold includes a second molding head and an array template for placing the glass, the array template is provided with a plurality of forming holes, and the forming holes are arranged at intervals in the array template; in the preparation of the microlens array layer, the second molding head presses the glass toward the array template so that the glass partially enters the forming holes to form the microlens structure.

[0021] In some embodiments, the preparation of the microlens array layer comprises the following steps:

[0022] S31: evacuating the heating chamber, filling the heating chamber with nitrogen, evacuating the chamber again, and then filling the heating chamber with an inert gas;

[0023] S32: positioning the second mold in the heating chamber, placing the glass hot-embossed with the anti-reflection layer into the second mold, and heating the glass to the second temperature;

[0024] S33: applying a second pressure to the glass by the second mold to form the microlens structure on the glass;

[0025] S34: Maintaining pressure on the second mold for a predetermined time and cooling the glass.

[0026] In some embodiments, the first temperature ranges from 580°C to 610°C, and the second temperature ranges from 530°C to 550°C.

[0027] The beneficial effect of the present application is that by first processing an anti-reflection layer on the surface of the optical glass and then processing a microlens array layer on the optical glass, the anti-reflection layer and the microlens array layer are located on the same side surface of the optical glass, thereby realizing the processing of the optical glass. The processing process is simple and has the advantages of high forming accuracy, high resolution, high consistency, high processing efficiency and low processing cost, and is very suitable for large-scale and large-area preparation needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or exemplary technical descriptions. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0029] Figure 1 is a flow chart of a method for preparing an anti-reflective microlens array provided in an embodiment of the present application;

[0030] Figure 2 1 is a schematic diagram of the three-dimensional structure of the second mold provided in an embodiment of the present application;

[0031] Figure 3 yes Figure 2 a schematic cross-sectional view of a second mold;

[0032] Figure 4 yes Figure 3 A local enlarged view of point A;

[0033] Figure 5 yes Figure 2 Schematic diagram of the explosion structure of the second mold.

[0034] Among them, the reference numerals in the figures are:

[0035] 10. Second mold; 11. Second molding head; 12. Positioning sleeve; 121. Ventilation hole; 13. Array template; 131. Forming hole; 200. Optical glass; 201. Microlens structure; DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit this application.

[0037] It should be noted that when a component is referred to as being "fixed on" or "disposed on" another component, it may be directly on the other component or indirectly on the other component. When a component is referred to as being "connected to" another component, it may be directly or indirectly connected to the other component. The terms "upper", "lower", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of description and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on this application. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances. The terms "first" and "second" are only used for the purpose of convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0038] See also Figures 1 to 3 The present invention provides a method for preparing an anti-reflective microlens array for processing glass.

[0039] The method for preparing the anti-reflective microlens array comprises the following steps:

[0040] S1: Prepare glass, a first mold, a second mold 10, and a heating device with a heating chamber; it is understood that the glass is an optical glass 200, wherein the model of the optical glass 200 can be BK-7 or D-K9. In this embodiment, the optical glass 200 is D-K9. In other embodiments, the optical glass 200 can be selected according to actual conditions and is not limited here. Among them, the Tg (transition temperature) of the D-K9 optical glass 200 is 497°C and the Ts (softening temperature) is 637°C. The heating chamber of the heating device generates heat through a resistance wire, thereby heating the glass to a predetermined temperature.

[0041] S2: Preparing an anti-reflection layer: The glass is heated to a first temperature within the heating chamber; a first mold is used to hot-emboss an anti-reflection micro-nanostructure onto the surface of the glass to form the anti-reflection layer; and the glass is cooled to solidify the processed micro-nanostructure. It is understood that the first temperature is greater than the transition temperature of the optical glass 200. In this embodiment, the first temperature is greater than Tg and less than Ts, thereby enabling hot-pressing of the optical glass 200. Micro-nanostructures are nanoscale geometric structures, including grooves or protrusions formed on the surface of the glass. In this embodiment, the micro-nanostructures are protrusions formed on the surface of the glass. In other embodiments, the number of micro-nanostructures can be selected based on practical needs and is not a limitation here. It is understood that multiple micro-nanostructures are arranged at intervals to form the anti-reflection layer. The micro-nanostructures are related to the wavelength of the incident light, causing the light to undergo multiple reflections and refractions between the micro-nanostructures before ultimately passing through the optical glass 200. This reduces light reflection from the optical glass 200 and improves light transmission efficiency.

[0042] S3: Preparing a microlens array layer, heating the glass to a second temperature in the heating chamber, and using a second mold 10 to hot-press a microlens structure 201 on the surface of the glass to form the microlens array layer. The anti-reflective micro-nanostructure and the microlens structure 201 are located on the same surface of the glass, and the size of the anti-reflective micro-nanostructure is smaller than the size of the microlens structure 201, and the anti-reflective micro-nanostructure is arranged on the microlens structure 201. It is understood that the size of the microlens structure 201 is micrometer-level or millimeter-level, and multiple are arranged in an array, and the surface of each microlens structure 201 is provided with multiple micro-nanostructures. The light incident surface of the microlens structure 201 is spherical or convex, so that it can achieve imaging, light uniformity, focusing, diffusion, collimation and other functions for light. It is understood that the second temperature is also greater than the transition temperature of the optical glass 200, the second temperature is greater than Tg and less than Ts, so that the microlens structure 201 can be formed on the surface of the optical glass 200, and the multiple microlens structures 201 form a microlens array layer.

[0043] S4: demolding, cooling the glass, and taking out the glass.

[0044] By first processing an anti-reflection layer on the surface of the optical glass 200 and then processing a microlens array layer on the optical glass 200, the anti-reflection layer and the microlens array layer are located on the same side surface of the optical glass 200, thereby realizing the processing of the optical glass 200. The processing process is simple and has the advantages of high forming accuracy, high resolution, high consistency, high processing efficiency and low processing cost. It is very suitable for large-scale and large-area preparation needs.

[0045] In some embodiments, the first temperature is greater than the second temperature. It is understood that the size of the anti-reflection layer is smaller than that of the microlens array layer. The smaller the size, the higher the fluidity requirements for the optical glass 200 during processing, and thus the higher the temperature of the optical glass 200. The second temperature is lower than the first temperature, thereby preventing deformation and damage to the anti-reflection layer during the preparation of the microlens array layer. Furthermore, the second temperature being lower than the first temperature can also anneal the anti-reflection layer, releasing internal stress in the anti-reflection layer and improving optical performance.

[0046] In some embodiments, the first mold includes a first pressing head and a micro-nano template on which the glass is placed, the micro-nano template having an anti-reflective micro-nano structure. During the step of forming the anti-reflective layer, the first pressing head presses the glass against the micro-nano template so that the anti-reflective micro-nano structure is replicated on the glass. Optionally, the micro-nano template is formed based on an anodized aluminum template having the micro-nano structure. The anti-reflective layer is then formed on the optical glass 200 using nanoimprint technology.

[0047] In some embodiments, the preparation of the anti-reflection layer comprises the following steps:

[0048] S21: Evacuate the heating chamber to a vacuum degree lower than 5 Pa, fill the heating chamber with nitrogen and evacuate the chamber again, and then fill the heating chamber with an inert gas, which may be argon or helium, to prevent the optical glass 200 from being oxidized at high temperatures.

[0049] S22: positioning the first mold in the heating chamber and placing the glass into the first mold, heating the glass to the first temperature, and keeping the temperature for 100 to 200 seconds so that the temperature of the optical glass 200 sample is evenly heated;

[0050] S23: applying a first pressure to the glass by the first mold to form the anti-reflection micro-nano structure on the glass by hot pressing; the first pressure ranges from 20 MPa to 60 MPa;

[0051] S24: The first mold is pressurized for a predetermined time, which ranges from 200 to 600 seconds, so that the micro-nano structure on the micro-nano template is fully filled and replicated to the optical glass 200, and finally nitrogen is filled in for annealing and cooling.

[0052] Optionally, the nitrogen flow rate is first controlled to adjust the cooling rate to 0.5-1°C / s, so that the optical glass 200 is slowly annealed to a temperature below 20°C of the glass transition point. Then, the nitrogen flow rate is increased to perform rapid cooling by 1-3°C / s until it reaches room temperature, and then demolding and sampling are performed.

[0053] In some embodiments, the micro-nano structure includes a plurality of anti-reflection protrusions arranged at intervals. The dimensions of the anti-reflection protrusions include height and inner diameter, wherein the height and inner diameter of the anti-reflection protrusions are both in the nanometer scale.

[0054] In some embodiments, the cross-sectional shape of the anti-reflective protrusion is circular, elliptical, or polygonal.

[0055] In some embodiments, the second mold 10 includes a second molding head 11 and an array template 13 for placing the glass. The array template 13 is provided with a plurality of forming holes 131, and the forming holes 131 are arranged at intervals in the array template 13. In the preparation of the microlens array layer, the second molding head 11 presses the glass toward the array template 13 so that the glass partially enters the forming holes 131 to form the microlens structure 201.

[0056] It can be understood that during the preparation process of the microlens array layer, the optical glass 200 is partially pressed into the forming hole 131, and the portion of the optical glass 200 located in the forming hole 131 is in a suspended state and does not contact the hole wall of the forming hole 131. Not only is the micro-nano structure retained, but the surface quality of the microlens structure 201 is not limited by the surface quality of the hole wall of the forming hole 131, so that a single microlens structure 201 can have a relatively high surface quality. By controlling the aperture and cross-sectional shape of the forming hole 131, the surface of the microlens structure 201 with a predetermined curvature can be formed, thereby reducing the processing cost of the array template 13.

[0057] Optionally, partially filling the forming holes 131 with the optical glass 200 can effectively reduce the deformation contact area between the optical glass 200 and the array template 13 , and reduce the adhesive shear friction contact area between the optical glass 200 and the array template 13 , which is beneficial to improving the service life of the array template 13 .

[0058] Optionally, the array template 13 is made of tungsten carbide.

[0059] In some embodiments, the preparation of the microlens array layer comprises the following steps:

[0060] S31: Evacuate the heating chamber to a vacuum degree lower than 5 Pa, fill the heating chamber with nitrogen and evacuate the chamber again, and then fill the heating chamber with an inert gas; the inert gas may be argon or helium, so as to prevent the optical glass 200 from being oxidized at high temperatures.

[0061] S32: positioning the second mold 10 in the heating chamber and placing the glass with the anti-reflection layer hot-embossed thereon into the second mold 10, heating the glass to the second temperature, and keeping the temperature for 50 to 200 seconds so that the optical glass 200 is evenly heated;

[0062] S33: The second mold 10 applies a second pressure to the glass, wherein the second pressure ranges from 1 to 10 MPa, to control the local filling of the morphology of the optical glass 200, so as to form the microlens structure 201 on the glass;

[0063] S34: Maintaining the pressure of the second mold 10 for a predetermined time and cooling the glass.

[0064] Optionally, the nitrogen flow rate is first controlled to adjust the cooling rate to 0.5-1°C / s, so that the optical glass 200 is slowly annealed to a temperature below 20°C of the glass transition point. Then, the nitrogen flow rate is increased to perform rapid cooling by 1-3°C / s until it reaches room temperature, and then demolding and sampling are performed.

[0065] Optionally, the second mold 10 further includes a positioning sleeve 12 , which is used to guide the second molding head 11 to move relative to the array template 13 . The positioning sleeve 12 is provided with a vent hole 121 , which is used to discharge gas in the positioning sleeve 12 .

[0066] In some embodiments, the first temperature ranges from 580°C to 610°C, and the second temperature ranges from 530°C to 550°C.

[0067] The method for preparing the anti-reflective microlens array provided in the embodiment of the present application is a flexible, controllable direct thermoforming technology, which realizes the construction of micro-nanostructures on the surface of the microlens array through two-step embossing. Compared with the direct processing of anti-reflective microlens arrays by femtosecond laser technology, this process has the advantages of simple operation, low processing cost, easy batch production, and high efficiency. It is possible to hot-stamp and replicate microlens array units of different curvatures and heights without processing a template structure of complex shape, greatly reducing the processing cost of the mold. In addition, microlens units of different curvature radii can be flexibly replicated by precise hot pressing temperature, pressure, time and other process parameters.

[0068] The above are merely optional embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for preparing an anti-reflective microlens array for processing glass, characterized in that: The method for preparing the anti-reflective microlens array comprises the following steps: preparing glass, a first mold, a second mold, and a heating device having a heating chamber; The anti-reflection layer is prepared by heating the glass to a first temperature in the heating chamber; using a first mold to hot-emboss an anti-reflection micro-nano structure on the surface of the glass to form the anti-reflection layer, wherein the micro-nano structure of the anti-reflection layer is a nanoscale geometric structure; and cooling the glass; The microlens array layer is prepared by heating the glass to a second temperature in the heating chamber, and using a second mold to hot-emboss a microlens structure on the surface of the glass to form the microlens array layer. The microlens structure has a size of micrometers or millimeters. The anti-reflective micro-nanostructure and the microlens structure are located on the same surface of the glass, and the size of the anti-reflective micro-nanostructure is smaller than that of the microlens structure. The anti-reflective micro-nanostructure is arranged on the microlens structure. The first temperature is greater than the second temperature to anneal the anti-reflective layer and release the internal stress of the anti-reflective layer. Demoulding and taking out the processed glass.

2. The method for preparing an anti-reflective microlens array according to claim 1, wherein: The first mold includes a first molding head and a micro-nano template for placing the glass, and the micro-nano template is provided with an anti-reflective micro-nano structure; in the step of preparing the anti-reflective layer, the first molding head presses the glass toward the micro-nano template so that the glass replicates the anti-reflective micro-nano structure.

3. The method for preparing an anti-reflective microlens array according to claim 1, wherein: The preparation of the anti-reflection layer comprises the following steps: S21: evacuating the heating chamber, filling the heating chamber with nitrogen, evacuating the chamber again, and then filling the heating chamber with an inert gas; S22: positioning the first mold in the heating chamber and placing the glass into the first mold, heating the glass to the first temperature; S23: applying a first pressure to the glass by the first mold to form the anti-reflective micro-nano structure on the glass by hot pressing; S24: Maintaining pressure on the first mold for a predetermined time and cooling the glass.

4. The method for preparing an anti-reflective microlens array according to claim 1, wherein: The micro-nano structure includes a plurality of anti-reflection protrusions arranged at intervals.

5. The method for preparing an anti-reflective microlens array according to claim 4, wherein: The cross-section of the anti-reflection protrusion is circular, elliptical or polygonal.

6. The method for preparing an anti-reflective microlens array according to any one of claims 1 to 5, wherein: The second mold includes a second molding head and an array template for placing the glass, the array template is provided with a plurality of forming holes, and the forming holes are arranged at intervals in the array template; In the preparation of the microlens array layer, the second molding head presses the glass toward the array template so that the glass partially enters the forming hole to form the microlens structure.

7. The method for preparing an anti-reflective microlens array according to any one of claims 1 to 5, wherein: The preparation of the microlens array layer comprises the following steps: S31: evacuating the heating chamber, filling the heating chamber with nitrogen, evacuating the chamber again, and then filling the heating chamber with an inert gas; S32: positioning the second mold in the heating chamber, placing the glass hot-embossed with the anti-reflection layer into the second mold, and heating the glass to the second temperature; S33: applying a second pressure to the glass by the second mold to form the microlens structure on the glass; S34: Maintaining pressure on the second mold for a predetermined time and cooling the glass.

8. The method for preparing an anti-reflective microlens array according to any one of claims 1 to 5, wherein: The first temperature ranges from 580 to 610°C, and the second temperature ranges from 530 to 550°C.

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