Characterization of 1-on-1 damage in high reflectors using the spatially-temporally resolved optical laser-induced damage (STEREO-LID) technique

Spatio-TEmporally REsolved Optical Laser-Induced Damage, or STEREO-LID, is a novel laser damage technique which measures the actual fluence (and intensity) at which damage occurs in a single pulse. This is accomplished by measuring the initiation time during the pulse and the initiation position within the beam profile. This technique has been demonstrated in the measurement of the defect distribution of single films and surfaces. In this paper, we demonstrate the technique to characterize laser-induced damage in high reflectors by single 8.3 ns pulses at 1064 nm. The high reflectors were quarter-wave stack of HfO 2 /SiO 2 on a fused silica substrate. Applying STEREO-LID to high reflectors required a change in geometry as the technique previously used light transmitted through the optic. Instead, the initiation time is identified by a disruption of reflection and scattered light. The initiation position is determined by imaging the backscattered laser light. The STEREO-LID results are compared to the traditional 1-on-1 damage test to show that it is superior at detecting critical fluence limiting defects.