Ultrasonic monitoring of laser damage in fused silica

The growth of a laser induced, surface damage site in a fused silica window was monitored by the ultrasonic pulse-echo technique. The laser damage was grown using 15 ns pulses of 1.053 mum wavelength light at a fluence of sim ilar to 25 J/cm(2). The ultrasonic signal amplitude exhibited variations wi th the damage size which are attributable to the changing subsurface morpho logy of the damage site. The sensitivity to subsurface morphology makes the ultrasonic methodology a promising tool for monitoring laser damage in fus ed silica optics. This type of diagnostic capability may facilitate the saf e deployment of large, high powered laser systems used in high energy and f usion research facilities. (C) 2001 American Institute of Physics.