Thermal deformation of optical windows induced by annularly distributed laser beam

By employing the limited Hankel integral transform, heat conduction and thermal deformation of optical windows induced by annularlydistributed laser beam are theoretically studied. The temperature increment and thermal deformation fields are expressed as infinite series. Then the theoretical results for sapphire and fused silica optical windows are calculated and compared with those from experiments. It is found that in 4s of irradiation, remarkable temperature rise occurs mainly in the irradiated annular area while its distribution over the whole window is far from a uniform one, so does the thermal deformation. Among all the parameters of materials', the absorption coefficient to incident laser and thermal expansion coefficient, and thermal diffusion coefficient are of the most importa