Transient Stress Imaging after Irradiation with a Focused Femtosecond Laser Pulse inside a Single Crystal

A focused femtosecond laser pulse inside a single crystal induces anisotropic structural changes, which depend on the atomic arrangement of the crystal. The transient stress after the photoexcitation should be responsible for the structural changes. In this study, we developed a novel transient stress observation system by time-resolved birefringence analysis and observed the relative amplitude and azimuth of the transient stresses after the photoexcitation inside MgO and LiF crystals. The principle and advantage of the observation system are described in this paper by comparing the system with a conventional stress observation method, a crossed-Nicols imaging method. (C) 2012 The Japan Society of Applied Physics