Abstract

Nonimaging optics provides a design tool for determining the precise shape of a pump cavity which couples all the radiation coming from the flashlamp into the laser rod. The design principle for the optimized cavity can be summarized as follows: extreme rays of a predetermined angle emerging from the light source are made to be incident on the laser rod at a predetermined angle by reflection from the appropriately shaped cavity. In this way, all radiation within the desired etendue is transferred from lamp to rod. Moreover, the irradiance on the laser rod is uniform. Commonly used pump cavity configurations are elliptical or have diffusely reflective walls. Accordingly, three cavity designs were evaluated experimentally: (1) a silver-coated aluminum cavity with an etendue preserving geometry; (2) a silver-coated aluminum cavity with an approximate elliptical geometry designed for the same rod and pump configuration as the etendue cavity; and (3) a commercially available diffuse-reflection laser pump cavity. The threshold and slope efficiency of each configuration were compared. The lasers were passively O-switched and the outputs used as a measure of the pump uniformity. In each case, the nonimaging cavity showed the best overall performance.

© 1986 Optical Society of America