Laser-induced Damage in Natural White Diamond

Abstract

A PREVIOUS report¹ has described laser-induced damage in optically transparent materials such as glass, alkali halides, CaF₂, MgO, sapphire and quartz; we wish to report the observation of this effect in natural white diamond. Intense, 0.3 joule, 10 MW pulses of 6943 Å radiation from a kryptocyanine Q-switched ruby were focused with a 5-cm focal-length lens on to the polished surfaces of the specimens. The dimensions of the specimens were very much smaller than the focal length of lens, thus ensuring that the power density of 10⁹ W/cm² incident on the surface was constant throughout the specimen. The damage on the front surface was characterized by a seared mark apparently consisting of black carbon (Fig. 1), which indicated that a high surface temperature was attained. The rear surface damage was characterized by extensive fractures and cracking (Fig. 2). Because of the difficulty in sectioning diamond, it was not possible to determine the depth of the physical damage; however, as this was not observed on the front surface of the specimens it seems apparent that it is characteristic of the rear surface only. This is consistent with the observed damage in other optically transparent materials¹.