Laser machining of optics to mitigate surface defects has greatly enhanced the ability to process large
optics such as those found in fusion-class lasers. Recently, the use of assist reactive gases has shown promise in
enhancing manifold etching rates relative to ambient conditions for CW-laser exposures. However, these methods
still require significant heating of the substrate that induce residual stress, redeposit coverage, material flow, and
compromise the final surface finish and damage threshold. While very reactive fluorinated gases are capable to
reduce treatment temperatures even further, they are also inherently toxic and not readily transferable to large
processing facilities. In this report, we look at whether a short-lived gas plasma could provide the safe and effective
etchant sought, while still reducing the thermal load on the surface. We test this approach using a YAG laserinduced
gas plasma to act as a source of the etchant for fused silica, a common optical material. The configuration
and orientation of the beam and optical apparatus with respect to the surface was critical in preventing surface
damage while etching the surface. Results with N2 and air gas plasmas are shown, along with a description of the
various experimental implementations attempted.
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