During the laser cutting of brittle material using controlled fracture technique, thermal stress is used to
induce the crack and the material is separated along the moving direction of the laser beam. In order to
investigated the process of pulsed Nd:YAG laser thermal stress cutting brittle silicon wafer, a
three-dimensional mathematical thermoelastic calculational model which contains a pre-existing crack
was established. The temperature field and thermal stress field in the silicon wafer were obtained by
using the finite element method. During the pulse duration, the changes of stress intensity factor around
crack tip were analyzed. Meanwhile the mechanism of crack propagation was investigated by
analyzing the development of the thermal stress field during the cleaving process, and the calculational
results in this paper are in agreement with the reported experiment results.
A new sensor based on optical beam shading technique for the investigation of mechanical effects during laser-metal
interaction is developed. This sensor is applied to detect the laser-induced plasma explosive impact and deformation
process during the explosion when a Q-switched laser is focused on a metal. The experimental results indicate that
elastic deformation and plastic deformation associated with the event induced by laser plasma the same time. This
technique has the advantages of high-frequency response, simple structure, and nondestructive examination.