The complex ray theory of photodeflection signal formation: Comparison with the ray theory and the experimental results

A theoretical study of Gaussian probe beam interaction with thermal waves on the basis of the complex geometrical optics equations is presented. This method of describing probe beam propagation in a nonhomogeneous medium, called the complex ray theory, takes into account the influence of the thermal wave on both amplitude and phase of electric field in the probe Gaussian beam. A comparison between the complex ray theory and previously proposed theories is made. Adequate experimental data confirming the correctness of the presented theory are also given. The least-squares procedure was used in multiparameter fitting the theoretical results to the experimental data and some parameters of the experimental setup were determined. It is proven that the complex ray theory allows correct quantitative interpretation of the data obtained in photodeflection experiments.