A method for preparing a large diffraction angle star pattern generating device

Abstract

The present invention discloses a method for preparing a large-diffraction-angle star pattern generator device. The device is formed by fusing two layers of microlens array structures, wherein the periods, spherical cap diameters, and sagittal heights of the two layers of array structures differ, and the coordinate axes are deflected at a certain angle. The present invention utilizes the characteristics of the two layers of microlens array structures having different geometric dimensions and the angle between the coordinate axes. Through a special preparation method, the two-layer micron-scale structure is fused into a single layer of a special structure with both micron-scale and nanometer-scale properties. This reduces the characteristic line width of the star pattern generator device from the micron-scale of the mask pattern to the nanometer-scale, significantly improving the diffraction angle. Furthermore, the preparation process does not require nanometer-scale processing technology, making it simple and easy to implement, and low in cost.

Description

Technical Field

[0001] The present invention belongs to the field of micro-nano optical technology, and in particular relates to a method for preparing a large diffraction angle star pattern generating device. Background Art

[0002] The star pattern generating device is a diffraction optical device commonly used in space scene demonstrations, science popularization teaching, and stage lighting effects.

[0003] The larger the diffraction angle of a diffractive optical device, the greater the image generation range of the monolithic device, the better the actual performance and the lower the cost. The diffraction angle depends on the characteristic linewidth of the diffractive optical device. For example, for a diffractive device with a wavelength of 600nm, when the diffraction full angle is 20°, its characteristic size is 1.70μm, and when the diffraction full angle is 70°, its characteristic size is 250nm. Therefore, large-angle diffractive optical devices are difficult to manufacture and have high processing costs due to the small characteristic size (nanometer level) of their micro-nanostructures.

[0004] The above factors limit the mass production and wide application of large diffraction angle star pattern generating devices. Therefore, there is an urgent need to develop a method for manufacturing large diffraction angle star pattern generating devices with simple technical principles and low processing costs. Summary of the Invention

[0005] In light of this, the present invention discloses a method for preparing a large-diffraction-angle star pattern generator device. The device is formed by fusing two layers of microlens array structures, wherein the periods, spherical cap diameters, and sagittal heights of the two layers differ, and the coordinate axes are deflected at a certain angle. By utilizing the different geometric dimensions and angled coordinate axes of the two layers of microlens array structures, and through a special preparation method, the two-layer micron-scale structure is fused into a single layer with both micron- and nanometer-scale characteristics. This reduces the characteristic linewidth of the star pattern generator device from the micron-scale of the mask pattern to the nanometer-scale, significantly improving the diffraction angle. Furthermore, the preparation process does not require nanometer-scale processing technology, reducing technical complexity and production costs.

[0006] The present invention is implemented by the following technical solution: A method for preparing a large diffraction angle star pattern generating device comprises the following steps:

[0007] The device is formed by fusing two layers of microlens array structures, wherein the periods, spherical crown diameters and sagittal heights of the two layers of array structures are different from each other, and there is a certain angle between the coordinate axes. The preparation method comprises the following steps:

[0008] Step 1: Design the size parameters of the two-layer microlens array structure, with different periods, spherical crown diameters, and sagittal heights, and use laser direct writing technology to make the first mask and the second mask;

[0009] Step 2, uniformly coating a layer of photoresist on the surface of the quartz substrate;

[0010] Step 3: using a contact mask exposure technique to copy the pattern of the first mask onto a photoresist, and after development, obtaining a cylindrical array of the first photoresist material;

[0011] Step 4: baking the cylindrical array using a photoresist thermal reflow method to form a microlens array structure of a first photoresist material;

[0012] Step 5: Transferring the microlens array structure to the surface of the quartz substrate using reactive ion etching technology to obtain a microlens array structure of a first layer of quartz material;

[0013] Step 6: coating a layer of photoresist on the surface of the microlens array structure;

[0014] Step 7: Using a contact mask exposure technique, the pattern of the second mask is copied onto the photoresist on the surface of the microlens array structure. Before exposure, the second mask is deflected at a certain angle to form a certain angle with the coordinate axis of the first mask. After development, a cylindrical array of the second photoresist material is obtained.

[0015] Step 8: baking the cylinder-like array by using a photoresist thermal reflow method to obtain a microlens array-like structure made of a second photoresist material;

[0016] Step 9: Using reactive ion etching technology to transfer the microlens array-like structure to the surface of the microlens array structure of the first layer of quartz material, a double-layer microlens array fusion structure formed by the fusion of the double-layer microlens array structure is prepared, that is, a new type of star pattern generating device.

[0017] Furthermore, the photoresist is AZ4620 photoresist.

[0018] Furthermore, the baking temperature used in step 4 and step 8 is 125°C.

[0019] The advantages of the present invention are:

[0020] (1) The present invention utilizes the characteristics of the two-layer microlens array structure, in which the geometric dimensions are different from each other and the coordinate axes are at an angle to each other, and through the above-mentioned preparation method, the double-layer micron-scale structure is integrated into a special structure with both micron-scale and nanometer-scale, so that the characteristic line width of the star pattern generating device is reduced from the micron-scale of the mask pattern to the nanometer-scale, and the diffraction angle is greatly improved.

[0021] (2) The present invention can realize the production of nanoscale structures through a specially designed micron-scale preparation method, and the preparation process does not require nanoscale processing technology, thereby reducing technical complexity and production costs.

[0022] In summary, the present invention discloses a method for preparing a large diffraction angle constellation pattern generating device. The constellation pattern generating device has a large diffraction angle, and the preparation method is simple and easy, with low processing cost, providing technical support for the mass production and wide application of large diffraction angle constellation pattern generating devices! BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0024] Figure 1 This is a flow chart of a method for preparing a large diffraction angle star pattern generating device disclosed in the present invention. The flowchart includes: 1 - first mask, 2 - second mask, 3 - quartz substrate, 4 - photoresist, 41 - cylindrical array structure, 42 - microlens array structure, 31 - microlens array structure of the first layer of quartz material, 43 - quasi-cylinder array structure, 44 - quasi-microlens array structure, and 32 - double-layer microlens array fusion structure.

[0025] Figure 2 Schematic diagram of the coordinate relationship between the two masks during the preparation process. DETAILED DESCRIPTION

[0026] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The scope of protection of the present invention shall include all the contents of the claims. Through the following embodiments, those skilled in the art can realize all the contents of the claims of the present invention.

[0027] Example 1:

[0028] like Figure 1 FIG2 is a flow chart of a method for preparing a large diffraction angle star pattern generating device disclosed in the present invention, which sequentially comprises the following steps:

[0029] The double-layer micro-lens array fusion structure 32 of the star pattern generating device made according to the target, such as Figure 1 As shown in Figure 1-1, first, two mask patterns are designed for two rounds of exposure process respectively. Note that the dimensional parameters of the two layers of microlens array structures, including period, spherical crown diameter, and sag height, are different. The first mask 1 and the second mask 2 are made using laser direct writing technology.

[0030] like Figure 1 As shown in 1-2, a layer of AZ4620 photoresist 4 is evenly coated on the surface of the quartz substrate 3;

[0031] like Figure 1As shown in 1-3, the pattern of the first mask 1 is exposed to the photoresist 4 using a contact mask exposure technique (exposure wavelength is 365 nm), and the photoresist is developed using AZ400K developer to obtain a cylindrical array 41 of the first photoresist material;

[0032] like Figure 1 As shown in FIG1-4 , the cylindrical array 41 of the photoresist material is baked at a temperature of 125° C., and a microlens array structure 42 of the first photoresist material is formed by utilizing the thermal reflow effect of the photoresist;

[0033] like Figure 1 As shown in 1-5, the microlens array structure 42 of the photoresist material is transferred to the surface of the quartz substrate 3 by using reactive ion etching technology to form a first layer of quartz material microlens array structure 31;

[0034] like Figure 1 As shown in 1-6, a layer of AZ4620 photoresist 4 is coated again on the surface of the microlens array structure 31 of the first layer of quartz material, and the upper surface is made flat by a self-leveling method;

[0035] like Figure 1 As shown in Figure 1-7, the pattern of the second mask 2 is exposed to the photoresist 4 using a contact mask exposure technique (exposure wavelength is 365 nm). Before exposure, the second mask 2 is deflected at a certain angle to form a certain angle with the coordinate axis of the first mask 1. The coordinate relationship of the two masks during exposure is as follows: Figure 2 As shown, the photoresist is developed using AZ400K developer to obtain a cylindrical array 43 of a second photoresist material;

[0036] like Figure 1 As shown in FIG1-8, the cylindrical array 43 of the second photoresist material is baked at a temperature of 125° C., and a microlens array structure 44 of the second photoresist material is obtained by utilizing the thermal reflow effect of the photoresist;

[0037] like Figure 1 As shown in Figure 1-9, the microlens array-like structure 44 of the second photoresist material is transferred to the surface of the microlens array structure 31 of the first layer of quartz material using reactive ion etching technology, thereby preparing a double-layer microlens array fusion structure 32 formed by the fusion of the double-layer microlens array structure, that is, a new type of star pattern generating device.

[0038] Parts of the present invention that are not described in detail belong to the common knowledge in the art.

[0039] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a large diffraction angle star pattern generating device, characterized in that: The device is formed by fusing two layers of microlens array structures, wherein the periods, spherical crown diameters and sagittal heights of the two layers of microlens array structures are different from each other, and there is a certain angle between the coordinate axes. The preparation method comprises the following steps: Step 1: Designing the size parameters of two-layer microlens array structures, wherein the period, spherical crown diameter and sagittal height of the two layers are different, and using laser direct writing technology to manufacture a first mask (1) and a second mask (2); Step 2: uniformly coating a layer of photoresist (4) on the surface of the quartz substrate (3); Step 3: using a contact mask exposure technique to copy the pattern of the first mask (1) onto the photoresist (4), and after development, obtaining a cylindrical array (41) of the first photoresist material; Step 4: baking the cylindrical array (41) by using a photoresist thermal reflow method to form a microlens array structure (42) of a first photoresist material; Step 5: Transferring the microlens array structure (42) to the surface of the quartz substrate (3) using reactive ion etching technology to obtain a first layer of quartz material microlens array structure (31); Step 6: coating a layer of photoresist (4) on the surface of the microlens array structure (31) of the first layer of quartz material; Step 7: using a contact mask exposure technique to copy the pattern of the second mask (2) onto the photoresist (4) on the surface of the microlens array structure (31); before exposure, the second mask (2) is deflected at a certain angle so as to form a certain angle with the coordinate axis of the first mask (1); and after development, a cylindrical array (43) of the second photoresist material is obtained; Step 8: baking the cylindrical array (43) using a photoresist thermal reflow method to obtain a microlens array structure (44) made of a second photoresist material; Step 9: Using reactive ion etching technology, the microlens array-like structure (45) is transferred to the surface of the microlens array structure (31) of the first layer of quartz material, thereby preparing a double-layer microlens array fusion structure (32) formed by fusing the double-layer microlens array structure.

2. The method for preparing a large diffraction angle star pattern generating device according to claim 1, characterized in that: The photoresist (4) is AZ4620 photoresist.

3. The method for preparing a large diffraction angle star pattern generating device according to claim 1, characterized in that: The baking temperature used in steps 4 and 8 was 125°C.

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