A study of stress and defect structures adjacent to laser-drilled holes in fused quartz

Photoelastic measurements of stresses in the vicinity of holes drilled in fused quartz with a CW CO 2 laser are reported. Stresses exist over a volume whose dimensions are defined by the thermal diffusion length for the heat pulse used. Incipient devitrification was noted in the vicinity of the hole, with large stresses often leading to fracture present at the boundary of the fused and devitrified phases.