Automated laser damage threshold test systems of different test modes for optical elements

Abstract

The automated laser damage threshold test systems of different test modes are developed recently with micron-scale damage events automated detection, location and re-inspection. The system is carried out using a 10 ns pulsed Nd:YAG laser with a repetition rate of 10 Hz. In view of the requirements of weak site identification and growth test for initial damage sites, we pay more attention to the raster scan protocol. The automated test system is enabled by the pulsed stage movement method. A one pulse to one image correspondence have been set up during scans, which is available for the later confirmation of the automated damage detection results and the growth study at specified test sites. The new and grown defects are decided by comparing the pre-image and current image at the same place during different scans. Currently, the defect comparison rules and tolerance are being optimized to improve the accuracy of test systems.

Resistance of Scratched Fused Silica Surface to UV Laser Induced Damage

“…Following the laser raster scanning, online microscopic image system (resolution ∼10 μm) was enabled to identify new and grown defects by comparing the pre-image and current image at the same place during different scanning regions. And the damage density can be extracted from the defects density before and after testing 8,16,17 . In view of a great number of scratches existing on sample C (30.08% ductile mixed with 2.25% brittle) and D (47.85% ductile mixed with 10.93% brittle), the microscopic images before and after laser scanning covered with a myriad of defects the damaged area was determined using the pixel discrepancy of defects before and after laser irradiation to quantitatively evaluate the damage performance of polished samples.…”

A Laser Damage Threshold for Microscope Glass Slides

“…Currently, these tests for the qualification of optical components for a given laser fluence are regulated by the ISO 21254 series standards [7][8][9][10]. According to these standards, there are several automated systems [11][12][13]. LIDT test stations working in atmospheric and vacuum environments have been developed and validated [14,15].…”