SYMPOSIA PAPER Published: 01 January 1990

The Effect of Subsurface Defects on “Incipient” (Below Threshold) Laser Damage Nucleation in Fused Silica Optical Flats


The development of subsurface defects in optical components has been extensively investigated by the authors and others over the past few years. Investigation of optical components using nondestructive photon backscattering (PBSTM), delineation etch/optical microscopy and charge decoration/delineation techniques has shown laterally variable spatial distributions of subsurface defects in the form of lineated remnant polishing traces, voids, and microscopic impurity clusters introduced during the surface finishing process. In this paper, we report on the correlation between nondestructive PBSTM mapping and delineation etch/optical microscopy techniques for detection of subsurface defects, as well as the effect of subsurface defects on the initiation of microscopic or “incipient” laser damage (λ= 248 nm) at levels below the point of macroscopic or catastrophic failure observed at the surface. The detection of laser induced microscopic cracking on nucleation sites within nondestructively identified areas provides additional insight into the progressive development of failure sites in distributed subsurface regions of low RMS, optically finished surfaces.

Author Information

Magee, TJ
Leung, CS
Orazio, FD
Boyer, JD
Mauro, BR
Sanders, VE
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Developed by Committee: E13
Pages: 230–238
DOI: 10.1520/STP26490S
ISBN-EB: 978-0-8031-5157-4
ISBN-13: 978-0-8031-4478-1