CO2 laser is used to prolong the lifetime of large optics for high power lasers such as the NIF and LMJ.
Indeed, on silica optical components, damaged sites, whose diameter is in the order of tens of microns, appear at
high UV laser fluence, and the size of such sites increases exponentially with each UV laser shot. An intense
heat by CO2 laser ejects the material from the surface of the optical component and removes all fractures around
the damaged site so that this site will not be damaged at fluences of operation of the UV laser. A crater is formed
at the site of initial damage. But the intense heat creates debris and residual stress around this crater. Due to these
debris and stress, the optical component is again weakened. We show here that a second heating process, done
with different settings of the CO2, named here laser annealing, eliminates the debris and reduce stress. The
results presented here establish that annealing significantly improves the resistance of laser optics.