Study of laser induced dynamics on macroscopic mirror

Light carries energy and momentum, which can be transferred to the irradiated target during the process of reflection, refraction or transmission. The energy transfer can be seen from heat generation and thermal expansion of the target, while the momentum can exert a microscopic force, called an optical force, that is extremely difficult to detect because it is so small. A theoretical model for describing the force distribution on a macroscopic spherical mirror irradiated by a single laser pulse is established in this study. Finite element analysis has been performed to predict the dynamics of the mirror and it shows good consistency with the experimental results. It indicates the differences in the variation of mechanical response due to the optical force and thermal deformation due to photon absorption. A parametric study was also performed to analyze the relationship between mirror geometry and laser dynamics. These studies verify the thermal-mechanical coupling in light-material interactions for a pulsed-laser irradiation model, thereby being applicable in precision measurement of optical force at a microscopic level. (paper)