Middle and far infrared high-absorptivity ultra-black diamond artificial microstructure laser direct writing method

Abstract

The invention discloses a laser direct writing method for a middle and far infrared high-absorptivity ultra-black diamond artificial microstructure, and belongs to the field of stray light suppression of a space optical system. Compared with a method for covering the surface with an ultra-black coating, the method for directly preparing the ultra-black structure on the diamond surface with the stable property is more reliable in an extreme environment and comprises the following preparation steps: (1) carrying out patterning etching treatment on the polycrystalline diamond surface by utilizing a femtosecond laser direct writing technology; (2) preparing a micro-nano structure with anti-reflection performance on the surface of the diamond by using a computer program to control specific processing parameters of a laser during patterning; and (3) carrying out a wave absorbing and transmitting rate performance test on the surface of the prepared patterned diamond. Compared with the prior art, the method has the advantages that the large-area periodic micro-nano structure ultra-black diamond surface which is extremely high in absorption rate of middle and far infrared bands 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 stray light suppression of space optical systems, and uses femtosecond laser direct writing technology to prepare an anti-reflection structure. 2. Background Technology

[0002] Unfavorable 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. Ultra-black 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 ultra-black surfaces suitable for use in space optical systems is of great significance to the aerospace industry and space exploration. Ultra-black surfaces are typically created using ultra-black coatings. For example, patent CN113245161 A achieves this by manipulating the mass fraction of carbon black colorant in a multi-layer spray coating process to create a thin film with a concentration gradient transition. However, due to the high vacuum and large temperature differences in the space environment, ultra-black surfaces created using ultra-black coatings are unstable in vacuum environments, and their preparation methods are complex and difficult to operate. Micro-nanostructures fabricated directly on material surfaces, however, 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 surface micro- and nanostructured materials can affect their absorptivity and transmittance across different wavelengths, providing a new approach for developing highly absorptive materials with specific wavelengths. Using surface micro- and nanostructures to create ultra-black surfaces is a superior preparation method due to its simplicity and controllability compared to ultra-black coatings. 3. Summary of the Invention

[0003] The present invention aims to conveniently produce an ultra-black diamond surface with high absorption in the mid- and far-infrared bands. The method provided uses a femtosecond laser to directly write an array structure onto the surface of a polycrystalline diamond to create an antireflection 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, the ideal surface micro- and nanostructures can be produced, resulting in an ultra-black surface with high absorption in the mid- and far-infrared bands. 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 laser direct writing of artificial microstructures of ultra-black diamond with high mid- and far-infrared absorption rate 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 surface of the polycrystalline diamond. Specific femtosecond laser processing parameters are set to obtain an anti-reflective micro-nanostructure.

[0008] Step 3: Test the absorptivity and transmittance performance of the diamond surface prepared by femtosecond laser in step 2.

[0009] Furthermore, the laser parameters in step 2 are: laser power 10 W, scanning speed 5 mm / s, scanning times 5 times, and period 30 μm.

[0010] Furthermore, the anti-reflection structure in step 2 can have a structural depth of up to 64.23 μm, and an aspect ratio (ratio of height to substrate length) of about 2.44.

[0011] Furthermore, the anti-reflection structure described in step 2 is a two-dimensional network structure.

[0012] Furthermore, the diamond surface described in step three has an average reflectivity of 1.85% and an average transmittance of 0.78% in the mid- and far-infrared long-wave range, and an average reflectivity of 0.89% and an average transmittance of 0.08% in the visible light and near-infrared bands. 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 ultra-black structure of the present invention

[0015] Figure 3 Schematic diagram of the diamond surface prepared for 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 the implementation process of the laser direct writing method of the present invention for a mid- and far-infrared high-absorption ultra-black diamond artificial microstructure, which includes 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 surface of the polycrystalline diamond is patterned and etched using femtosecond laser direct writing technology, and the resulting anti-reflection structure is a two-dimensional mesh, the center distance between two adjacent peaks is 30μm, the structure depth is 64.23μm, and the aspect ratio is about 2.44.

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

[0021] This invention describes a laser direct writing method for artificial microstructures of ultra-black diamond with high mid- and far-infrared absorptivity. The goal is to create a stable, ultra-black micro- and nanostructured surface with high absorptivity in the mid- and far-infrared bands using a relatively simple method. The resulting micro- and nanostructures are characterized by an average reflectivity of 1.85% and an average transmittance of 0.78% in the long-wavelength mid- and far-infrared bands, demonstrating high absorptivity in the mid- and far-infrared bands.

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

[0023] 1. The present invention's mid- and far-infrared high-absorption ultra-black diamond artificial microstructure laser direct writing method does not require a mask, but uses femtosecond laser direct writing to prepare an anti-reflection structure. The processing method is simpler than existing methods.

[0024] 2. The laser direct writing method of the present invention for a mid- and far-infrared high-absorption ultra-black diamond artificial microstructure uses femtosecond laser direct writing to prepare an anti-reflection structure, which can be prepared on a large area.

[0025] 3. During the processing of the laser direct writing method for artificial microstructure of ultra-black diamond with high absorption rate in the mid- and far-infrared region of the present invention, the etching shape and etching depth can be controlled by a computer program to achieve ideal experimental results.

[0026] 4. The ultra-black surface structure of the laser direct writing method of an artificial microstructure of ultra-black diamond with high mid- and far-infrared absorption rate of the present invention is stable under extreme environments and will not produce significant changes in absorption performance as the environment changes.

[0027] The ultra-black surface structure prepared by the laser direct writing method of the ultra-black diamond artificial microstructure with high mid- and far-infrared absorption rate of the present invention can meet the high absorption capacity in the mid- and far-infrared bands, and has important research significance for fields such as aerospace infrared satellites or optical windows.

Claims

1. A laser direct writing method for artificial microstructure of ultra-black diamond with high absorption rate in mid- and far-infrared, 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 surface of the polycrystalline diamond. Specific femtosecond laser processing parameters are set to obtain an anti-reflective micro-nanostructure. Step 3: Perform absorptivity and transmittance performance tests on the diamond surface prepared by femtosecond laser in step 2 to ensure that the absorbency and transmittance of the prepared functional material in the infrared band meet the expected requirements.

2. The method for laser direct writing of artificial microstructures of ultra-black diamond with high mid- and far-infrared absorption rate according to claim 1, characterized in that: The laser parameters described in step 2 are: laser power 10 W, scanning speed 5 mm / s, number of scans 5 times, and period 30 μm.

3. The method for laser direct writing of artificial microstructures of ultra-black diamond with high mid- and far-infrared absorption rate according to claim 1, characterized in that: The anti-reflection structure described in step 2 can have a structural depth of up to 64.23 μm, and an aspect ratio (ratio of height to substrate length) of about 2.

44.

4. The method for laser direct writing of artificial microstructure of ultra-black diamond with high absorption rate in mid- and far-infrared according to claim 1, characterized in that: The anti-reflection structure described in step 2 is a two-dimensional network structure.

5. The method for laser direct writing of artificial microstructure of ultra-black diamond with high absorption rate in mid- and far-infrared according to claim 1, characterized in that: The average reflectivity of the diamond surface in step 3 in the mid-to-far infrared long-wave range is 1.85%, and the average transmittance is 0.78%.

Images