Thermal lensing effect of solid state lasers is a critical parameter. The efficiency and output power of lasers are strongly influenced by it. This thesis is composed of three parts.
At first, a theoretical approach for trant temperature in a single pulse pumped laser rod is developed. Measurements have been made of the change of the optical path length due to thermal transient effects of Nd:YAG laser rod. Experimental data were obtained by passing a He-Ne probe beam through the flash lamp pumped laser rod and recording the detector output as a function of time. Using transient detector output, the temperature relaxation time and the heat transfer coefficient were determined. Second, thermally induced focal length was measured for pulsed optical pumping conditions. The equilibrium induced focusing is shown to depend on average pump power. Third, thermally induced wave front change of probe beam was obtained by placing the sample in a Twymann - Green interferomater. Using this wave front, thermal focal length was determined. It was compared with previous data. It was observed that the thermal focal length of the center of the rod is less than that of the edges.
