US Patent 7330250 Nondestructive evaluation of subsurface damage in optical elements

A non-destructive process for evaluating subsurface damage in an optical element focuses a microscope at points within the optical element and measures the intensity of reflected light. In one embodiment, a microscope focus a laser beam at a measurement point with the optical element and also collects reflected or scattered light from damage in the optical element. Analysis of data indicating the reflected intensities for a three-dimensional array of points within the optical element can determine the location and severity of the subsurface damage.