Design characteristics and some applications of the ruby laser

Abstract

This thesis is concerned with the solid state ruby laser, and the determination of the optimum design parameters upon which its performance is dependent. The voltage, current and light output characteristics of the linear xenon flashtuhes used for excitation are measured for different discharge circuit conditions, and the efficiency of laser operation is related to these different operating conditions. It is shown that two factors affect the coupling efficiency of the cylindrical ellipse which is used to transfer the radiation emitted by flashtube to the ruby rod: its geometric shape and the reflectivity of its walls. The theory describing the coupling efficiency of the single elliptical cavity is extended for the case of multiple section elliptical cavities, and experimental measurements of laser output energy and efficiency are made for both single and double cavities which are found to agree with theoretical predictions. A theory relating the optimum laser mirror reflectivity to the ruby dimensions and pump energy is developed, for which laser output energy measurements made with ruby rods from 2" to 6(^1)(_2) in length are found to be in agreement. This work also enables the total internal loss of each ruby to be determined and thus gives a method of assessing their quality. It is also demonstrated that the laser efficiency is strongly dependent upon the ruby temperature and the laser output energy is measured at temperatures of up to 50ºC above ambient conditions. The last chapter is concerned with a theoretical and practical assessment of the application of the ruby laser for machining and welding.