[Thermal effects of a short light pulse on biological tissues. II. Light and heat fields]

A set of heat conduction equations for a two-component medium simulating biological tissues were formulated. Their solutions were obtained, and the spatial distribution of light and temperature over tissue depth at different times after irradiation by a short light pulse was studied. The local absorption of light by blood vessels and the influence of this effect on the optical parameters of the medium, a more intense heating of blood as compared with its surrounding tissue, heat exchange between them, and heat transfer at the interface with different environments were accounted for. The solutions are expressed via characteristic times of the respective thermal processes to enable one to easily and vividly analyze the features of tissue heating and the influence of optical and thermal parameters on the temperature distributions of the components. The calculations are illustrated by examples.