PHOTOLUMINESCENCE IMAGING OF MECHANICALLY PRODUCED DEFECTS IN MGO

Deformed MgO displays a strong blue photoluminescence when illuminated by 248 nm excimer laser radiation. This photoluminescence is readily imaged in situ (during laser exposure) using commercial microscope optics. Photoluminescence images of indented, cleaved, abraded, and laser-damaged surfaces, are reported and the observed features are related to the expected deformation patterns. Locally deformed regions on MgO single crystals are sites of localized absorption at 248 nm and serve to nucleate localized damage under high fluence irradiation. Photoluminescence imaging has great potential for the identification of flaws in optical materials prior to, during and after exposure to damaging fluences of laser radiation and for fundamental studies of deformation, fracture and tribology.