Surface treatment method for increasing fused silica element threshold value through wet etching-dry etching combination

Abstract

The invention discloses a surface treatment method for increasing a fused silica element threshold value through wet etching-dry etching combination, belongs to the technical field of optical materials and optical elements, and particularly relates to a surface treatment method for increasing a fused silica element laser damage threshold value. According to the surface treatment method, deionized water is adopted to wash the surface of a fused silica element processed by using the traditional grinding polishing process, dehydrated alcohol is adopted to carry out ultrasonic washing, the obtained fused silica element is subjected to an etching treatment by using a hydrofluoric acid solution, deionized water washing and dehydrated alcohol dehydration are performed, and finally an energetic inert ion beam is adopted to carry out surface polishing to remove the acid etching reaction product SiF6<2-> and improve the surface roughness. According to the present invention, the residual polishing powder on the fused silica element processed by using the traditional process can be removed, the defect can be subjected to passivation, and the good surface roughness can be obtained, such that the laser damage resistance of the fused silica element can be effectively increased.

Description

technical field [0001] The invention belongs to the technical field of optical materials and optical elements, and in particular relates to a surface treatment method for increasing the laser damage threshold of fused silica elements. Background technique [0002] Fused silica is one of the most widely used and used optical materials in high-power solid-state laser devices, and is widely used in the preparation of optical components such as lenses, gratings, windows and shielding sheets. Because the surface of traditionally processed fused silica components contains surface and subsurface defects such as scratches and polished deposits, these defects will cause strong modulation of the incident laser light here, and the residual polishing powder on the surface of the component and inside the defects is particularly harmful to the incident laser light. It is the strong absorption of ultraviolet laser, and these factors cause the surface damage threshold of fused silica compon...

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Problems solved by technology

This method can effectively and quickly remove the residual polishing powder on the surface of the component and passivate the defects, but this method has two disadvantages: first, the surface morphology of the component is not controlled, and the size of defects such as scratches after etching will change in both vertical and horizontal directions. If the etching time is too short, the deposition layer and impurities will not be removed completely. If the etching time is too long, the surface roughness of the component will increase and the surface shape may be affected. Both of these situations will affect the light transmission characteristics of the component. , to reduce the anti-laser damage ability of components, such as "Studies on in-situ characterization and damage threshold of fused silica subsurface defects" (see "Optoelectronics Laser" 2010, 21(10), 1519, Jiang Yong, Yuan Xiaodong, Xiang Xia, etc.); Second, the chemical reaction product SiF 6 2－ It is easy to deposit on the etched surface, but reduces the laser damage threshold of the component

Although the United States has adopted megasonic dynamic acid etching to overcome SiF 6 2－ Deposition issues such as "HF-Based Etching Processes for Improving Laser Damage Resistance of Fused Silica Optical Surfaces" (see Journal of the American Ceramic Society2011, 94:416, TI Suratwala, PE Miller, JD Bude, etc.), but surface roughness remains It is uncontrolled, pollutes the environment a lot, and has high requirements for equipment

Dry etching such as ion beam milling generates cascade collisions by bombarding the surface of the material with energetic ions, thereby sputtering the surface atoms. This atomic-level removal method can control the morphology, and it is easy to obtain an ultra-smooth surface with average roughness Less than 0.2nm, such as "Morphology evolution of fused silica surface during ion beam figuring of high-slope optical components" (see Applied Optics2013, 52: 3719, WL Liao, YF Dai, XH Xie, etc.), but because it is removed at the atomic level , so the etching efficiency is relatively low, and the processing cycle is too long

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