A kind of cleaning method before coating on lbo crystal surface

Abstract

The invention relates to a method for cleaning the LBO crystal surface before coating. The LBO crystal is subjected to the following steps in sequence: a mixture of absolute ethanol and ether is used to wipe the LBO crystal surface; a weak alkaline solution is used to ultrasonic clean the LBO crystal. The weakly alkaline solution includes NH4OH and H2O2, the volume ratio is NH4OH:H2O2:H2O=1:8:50; use absolute ethanol to rinse the LBO crystal; place the LBO crystal in a sealed container filled with absolute ethanol, and The LBO crystal is cleaned by ultrasonic heating; the LBO crystal is taken out and rinsed again; the LBO crystal is dried using a dry nitrogen air knife in a positive pressure container environment. Compared with the existing technology, the present invention has the advantages of good cleaning effect, can not only improve the laser damage resistance of the LBO crystal after coating, but also improve the film adhesion and crack resistance after coating.

Description

technical field [0001] The invention relates to a laser crystal ultrasonic cleaning method, in particular to a cleaning method before the surface of LBO crystal is coated. Background technique [0002] Lithium triborate crystal (LBO crystal) is an orthorhombic crystal system, which has a very high damage threshold and UV transmittance, and also has a good frequency doubling effect. Therefore, it has broad application prospects in the development of frequency doubling and parametric oscillator devices for high-power lasers, and is currently a commonly used nonlinear optical crystal in high-power lasers. In order to reduce the energy loss caused by the interface Fresnel reflection and improve the operating efficiency of the system, the LBO crystal must be coated with a high-performance laser antireflection film on its surface. However, due to the weak deliquescence characteristics of the LBO crystal and its thermal expansion coefficient Significant anisotropy (α x =10.8×10 ...

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Problems solved by technology

Among them, the wiping method is more effective for large-scale particles above microns, but it is difficult to remove sub-micron particles; RCA cleaning belongs to chemical cleaning, which can reduce the adsorption force between particles and the substrate, but if the solubility of the chemical solution is not properly controlled Causes severe corrosion of the substrate, resulting in an increase in surface roughness; ultrasonic cleaning can efficiently remove particles of various sizes from micron to submicron on the surface of the substrate through the selection of ultrasonic cleaning frequency. , will cause physical damage to the substrate surface, these defects will not only seriously affect the optical properties of the substrate but also may lead to catastrophic laser damage

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