Using quantum dots to evaluate subsurface damage depths and formation mechanisms in glass

Subsurface damage (SSD) is a layer of fractured and stressed material that remains beneath an apparently well polished surface. It is detrimental to the quality and performance of high end optical components and laser crystals. While many methods exist to detect SSD none offer insights into damage formation mechanisms and few estimate damage depths. The technique of tagging lapping and polishing slurries with quantum dots (nano-sized fluorescent crystals) does both. Fluorescence was detected at depths up to 10 μm beneath the surface of glass slides processed with tagged slurries. The dots are introduced to the subsurface through brittle fracture mechanisms.