Organic contaminants on optical components can degrade optical properties, thus limiting the energy enhancement of highpeak-
power laser systems. It is still challenging to remove organic contaminants on the SiO2 sol-gel antireflection film and
avoid damage. In this work, a low-pressure air plasma in-situ cleaning technique and a chemical reaction model of plasma
cleaning were proposed to study the removal of organic contaminants. The optical properties of sol-gel AR films suffered
from organic contaminants were evaluated by transmittance and laser-induced damage threshold, which recovered
completely after 5 minutes of plasma cleaning without damage. Meanwhile, the hydrophilicity of the surface and the
surface free energy were significantly increased after plasma treating. Surface composition analysis indicated that the CH
and C-C bonds were reduced considerably, while abundant C=C and C=O bonds were produced after plasma cleaning.
Optical emission spectrum analyzed the reactive species and its concentration in the air plasma as a reference for simulation.
The chemical interaction process of oxygen radicals with organic contaminants was simulated by reactive molecular
dynamics. The results can provide a guide for optical components in-situ cleaning.
The cleaning mechanism of optical surface particle contaminants in the light pneumatic tube was simulated based on the static equations and JKR model. Cleaning verification experiment based on air knife sweeping system and on-line monitoring system in high power laser facility was set up in order to verify the simulated results. Results showed that the removal ratio is significantly influenced by sweeping velocity and angle. The removal ratio can reach to 94.3% by using higher input pressure of the air knife, demonstrating that the air knife sweeping technology is useful for maintaining the surface cleanliness of optical elements, and thus guaranteeing the long-term stable running of the high power laser facility.
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