Quasi-one-dimensional thermal deformation and displacement of the surface of a solid in a pulsed laser beam

Abstract

Relatively simple equations are presented for the description of the kinetics of quasi-static displacements and deformations of a solid in a pulsed laser beam at different distances from the center of a Gaussian beam for surface light absorption. A comparison with experiment is carried out for a metal (radius of heating beam ω⊃25 µm, typical pulse duration τ∼0.4 µsec) for distances up to ∼2ω from the center. An analysis is reported of the conditions for quasi-one-dimensional displacement with a characteristic displacement ‘buildup’ (in time) that is proportional to the energy absorbed at a given point, but is independent of the temperature diffusivity of the material. It is shown that the displacement and deformation kinetics are very different inside and outside the heating beam. In particular, the kinetics in peripheral regions is different from the quasi-one-dimensional kinetics even at the early stages of developing the displacements.