The purpose of this study is to analyze the heat-affected zone in materials such as meat samples, araldite resin-simulating tissue phantoms, and fiber composites irradiated using a mode-locked short pulse laser with a pulse width of 200 ps. The radial surface temperature profiles are compared with that of a continuous wave (CW) laser of the same average power. The short pulse laser results in a more localized heating than a continuous laser with a corresponding high peak temperature. A parametric study addressing the effect of pulse train frequency, material thickness, and amount of scatterers and absorbing agent in the medium and different initial sample temperatures is performed, and the measured temperature profiles are compared with the theoretical non-Fourier hyperbolic formulations and Fourier parabolic heat conduction formulations for both CW and pulsed laser cases.

We examine the transport of short light pulses through scattering–absorbing media through different approximate mathematical models. It is demonstrated that the predicted optical signal characteristics are significantly influenced by the various models considered, such as P _N expansion, two-flux, and discrete ordinates. The effective propagation speed of the scattered radiation, the predicted magnitudes of the transmitted and backscattered fluxes, and the temporal shape and spread of the optical signals are functions of the models used to represent the intensity distributions. A computationally intensive direct numerical integration scheme that does not utilize approximations is also implemented for comparison. Results of some of the models asymptotically approach those of direct numerical simulation if the order of approximation is increased. In this study therefore we identify the importance of model selection in analyzing short-pulse laser applications such as optical tomography and remote sensing and highlight the parameters, such as wave speed, that must be examined before a model is adopted for analysis.