Damage to large optics by focusing acoustic transients, revision 2
Abstract
Damage was observed to 80 cm diam fused silica disks and lenses subjected to high fluence pulses (up to 2.3 J/sq cm) from an upgraded Nova laser beamline (wavelength 351 nm; pulse duration 2.35 ns; beam diameter 70 cm; energy up to 8 kJ). Damage occurred in the center of each element, where a 6 cm wide obscuration prevented direct illumination. It is believed that light strongly scattered by transverse stimulated Brillouin scattering (SBS) interacts with the surface and with the bulk of the substrate, producing two kinds of acoustic waves that propagate to its center, where they become strong enough to do damage. Design rules are proposed for avoiding acoustic damage in large optics and compare observed thresholds for transverse SBS with predictions in the literature.
- Publication:
-
Presented at the CLEO/Quels 1989 Conference
- Pub Date:
- April 1989
- Bibcode:
- 1989cleo.conf...24S
- Keywords:
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- Brillouin Effect;
- Nova Laser System;
- Optical Equipment;
- Radiation Damage;
- Acoustics;
- Fluence;
- Lenses;
- Light Scattering;
- Sound Waves;
- Optics