Laser direct writing method for infrared low-reflection zinc sulfide artificial microstructure

Abstract

The invention discloses a laser direct writing method for an infrared low-reflection zinc sulfide artificial microstructure, and relates to the technical field of infrared optical surfaces. Compared with a method for evaporating a zinc sulfide film on the surface, the method for directly preparing the high-reflection structure on the stable zinc sulfide surface is more reliable in an extreme environment, and the preparation method comprises the following steps: (1) carrying out patterning etching treatment on the zinc sulfide surface by utilizing a femtosecond laser direct writing technology; (2) controlling specific processing parameters of a laser during patterning by using a computer program to prepare a micro-nano structure with low reflection performance on the surface of the zinc sulfide; and (3) carrying out reflectivity performance test on the prepared patterned zinc sulfide surface. Compared with the prior art, the method has the advantages that the large-area low-reflectivity zinc sulfide surface which is extremely low in infrared band reflectivity and good in shape and size is prepared in a simple mode, and the method has important research significance in the fields of spaceflight infrared satellites or optical windows and the like.

Description

1. Technical Field

[0001] The invention belongs to the field of infrared optical surface technology, uses femtosecond laser direct writing technology to prepare low-reflection structures, and specifically relates to a laser direct writing method for infrared low-reflection zinc sulfide artificial microstructures. 2. Background Technology

[0002] Adverse conditions in space, such as incident stray light and unwanted reflections from interfaces, can degrade the performance of space optical payloads, such as optical cameras, detectors, and solar energy converters. These adverse effects can reduce the signal-to-noise ratio, sensitivity, and reliability of optical equipment. To improve the performance of space optical payloads, it is necessary to eliminate the adverse effects of stray light. Low-reflection surfaces can effectively reduce reflections that interfere with optical payload imaging within a certain range and significantly absorb stray light from the material surface. Therefore, the development of highly absorptive, low-reflection surfaces for use in space optical systems is of great significance to the aerospace industry and space exploration. Low-reflection surfaces are typically created by coating multiple layers of various materials, such as in patent CN 210572831U, where thin films of different materials of specific thicknesses are deposited from the inside out onto a curved substrate. However, due to the high vacuum and large temperature differences in the space environment, low-reflection surfaces created by coating are unstable in vacuum environments, complex to prepare, and difficult to operate. However, two-dimensional grid structures fabricated directly on material surfaces possess numerous excellent physical and chemical properties and are highly stable, possessing broad application potential and attracting significant scientific attention in recent years. Recent research has found that creating specific micro-nanostructures on a material's surface can affect its reflectivity across different wavelengths, providing a new approach for developing highly absorptive materials with specific wavelengths. Using specific surface structures to create low-reflectivity surfaces is a superior preparation method compared to multilayer plating, due to its simplicity and controllability. 3. Summary of the Invention

[0003] The present invention aims to conveniently produce a zinc sulfide surface with low infrared reflectivity. The method provided uses a femtosecond laser to directly write an array structure onto the zinc sulfide surface to create a low-reflectivity layer. This laser direct writing method eliminates the need for a mask, a vacuum environment, or subsequent material processing, making the process convenient and relatively inexpensive. Using a computer program, ideal surface micro-nanostructures can be produced, resulting in low infrared reflectivity. This method has important research implications for applications such as aerospace infrared satellites and optical windows.

[0004] To achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions:

[0005] A method for preparing a low-reflection zinc sulfide surface in the infrared band comprises the following steps:

[0006] Step 1: Build a femtosecond laser processing system;

[0007] Step 2: Using femtosecond laser direct writing technology, the etching process is controlled by a computer program to perform laser patterning on the zinc sulfide surface. Specific femtosecond laser processing parameters are set to obtain low-reflection micro-nanostructures.

[0008] Step 3: Test the reflectivity performance of the zinc sulfide surface prepared by femtosecond laser in step 2.

[0009] Furthermore, the laser parameters in step 2 are: laser power 150 mW, scanning speed 10 mm / s, scanning number 1, and period 25 μm.

[0010] Furthermore, the low-reflection structure in step 2 has a structural depth of approximately 3.54 μm and an aspect ratio (ratio of height to substrate length) of approximately 2.44.

[0011] Furthermore, the low-reflection structure in step 2 is a two-dimensional mesh structure.

[0012] Furthermore, the average reflectivity of the surface of the grid array microstructured zinc sulfide in the infrared band described in step three can be reduced to 2.32%. IV. Description of the Figures

[0013] Figure 1 This is an example diagram of the femtosecond laser processing system of the present invention

[0014] Figure 2 Flowchart for preparing low reflective surface for the present invention

[0015] Figure 3 Schematic diagram of the zinc sulfide surface prepared by the present invention V. Specific Implementation Methods

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0017] The following specifically describes a method for direct laser writing of an infrared low-reflection zinc sulfide artificial microstructure according to the present invention, comprising the following steps:

[0018] (1) Build Figure 1The femtosecond laser processing system shown in FIG. comprises a femtosecond laser 1, an aperture 2, an attenuation plate 3, an optical shutter 4, a dichroic mirror 5, an objective lens 6, a material to be processed 7, a three-dimensional displacement platform 8, a charge-coupled device (CCD) 9, and a computer 10. After being generated by the femtosecond laser 1, femtosecond laser light with a wavelength of 1035 nm, a pulse width of 130 fs, and a repetition rate of 5000 Hz passes through the aperture 2, the attenuation plate 3, and the optical shutter 4. It is then reflected by the dichroic mirror 5 onto the objective lens 6. The objective lens 6 then focuses the femtosecond laser light onto the surface of the material to be processed 7. An image of the material to be processed 7 is reflected by the dichroic mirror 5 and displayed on the charge-coupled device (CCD) 9. Under control of the computer 10, the image on the CCD 9 can be displayed on a computer screen. The laser flux can be adjusted by controlling the attenuation plate 3. The optical shutter 4 can be controlled by the computer 10.

[0019] (2) Figure 2 As shown, the zinc sulfide surface is patterned and etched using femtosecond laser direct writing technology, and the low-reflection structure obtained is a two-dimensional network, the center distance between two adjacent peaks is 25μm, the structure depth is 3.54μm, and the aspect ratio is about 2.44.

[0020] 6. Effects of the Implementation of the Invention

[0021] The present invention provides a method for laser direct writing of infrared low-reflective zinc sulfide artificial microstructures. This method aims to produce a stable, low-reflectivity surface with high infrared absorptivity using a relatively simple method. The finished surface is characterized by an average reflectivity of 2.32% in the infrared band, which meets the low-reflectivity requirements of the infrared band.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. The infrared low-reflection zinc sulfide artificial microstructure laser direct writing method of the present invention does not require the use of a mask, but uses femtosecond laser direct writing to prepare the low-reflection structure. The processing method is simpler than the existing method.

[0024] 2. The infrared low-reflection zinc sulfide artificial microstructure laser direct writing method of the present invention uses femtosecond laser direct writing to prepare low-reflection structures, which can be prepared on a large area.

[0025] 3. During processing, the infrared low-reflection zinc sulfide artificial microstructure laser direct writing method of the present invention can control the etching shape and etching depth through a computer program to achieve ideal experimental results.

[0026] 4. The low-reflection structure of the infrared low-reflection zinc sulfide artificial microstructure laser direct writing method of the present invention is stable under extreme environments and will not produce significant changes in reflective performance as the environment changes.

[0027] 5. The ultra-black surface structure prepared by the infrared low-reflection zinc sulfide artificial microstructure laser direct writing method of the present invention can meet the high absorption capacity of the infrared band, and has important research significance for fields such as aerospace infrared satellites or optical windows.

Claims

1. A method for direct laser writing of infrared low-reflection zinc sulfide artificial microstructures, characterized in that The preparation method is achieved by the following steps: Step 1: Build a femtosecond laser processing system. The femtosecond laser processing system consists of a femtosecond laser, an aperture, an attenuation plate, an optical shutter, a dichroic mirror, an objective lens, the material to be processed, a three-dimensional mobile platform, an electrical coupling element, and a computer. The femtosecond laser with a wavelength of 1035nm, a pulse width of 130fs, and a repetition frequency of 5000Hz is generated by the femtosecond laser, passes through the aperture, attenuation plate, and optical shutter, and is reflected by the dichroic mirror onto the objective lens. After being focused by the objective lens, the femtosecond laser is focused on the surface of the material to be processed. Step 2: Using femtosecond laser direct writing technology, the etching process is controlled by a computer program to perform laser patterning on the zinc sulfide surface. Specific femtosecond laser processing parameters are set to obtain a low-reflectivity surface thin film structure. Step 3: Conduct a reflectivity performance test on the zinc sulfide surface prepared by femtosecond laser in step 2 to ensure that the reflectivity of the prepared functional material in the infrared band meets the expected requirements.

2. The method for preparing a low-reflection zinc sulfide surface in the infrared band according to claim 1, characterized in that: The laser parameters described in step 2 are: laser power 150 mW, scanning speed 10 mm / s, scanning number 1, and period 25 μm.

3. The infrared low-reflection zinc sulfide artificial microstructure laser direct writing method according to claim 1, characterized in that: The low-reflection structure described in step 2 has a structural depth of approximately 3.54 μm, an aspect ratio (ratio of height to substrate length) of approximately 2.44, and a surface roughness of approximately 256 nm.

4. The infrared low-reflection zinc sulfide artificial microstructure laser direct writing method according to claim 1, characterized in that: The low-reflection structure described in step 2 is a two-dimensional network structure.

5. The infrared low-reflection zinc sulfide artificial microstructure laser direct writing method according to claim 1, characterized in that: The reflectivity of the grid array microstructured zinc sulfide surface in the infrared band is 2.32% in step three.

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