Fast Measurement Technique For Obtaining The Low Damage Threshold Defects In A Large Aperture Fused Silica Glass

Measurement of the low damage threshold defects in a large aperture fused silica glass is of great significance. Currently, the popular characterization method for detecting the low damage threshold defects is via measuring the optical absorption of a fused silica glass using the surface thermal lensing technology. However the detecting area of a single shot in this method is too small, typically around 10x10 microns, so if a large aperture fused silica glass in the size of 400x400 mm is to be measured, it would take approximate 100000 hours to complete the measurement, which is obviously not acceptable. Here, we report a fast measurement technique for obtaining the low damage threshold defects in a large aperture fused silica glass according to its fingerprint spectrum, for the fused silica optical glass in the size of 400x400 mm, measurement of the low damage threshold defects in the whole surface in several hours is achievable.