Development of a Beaam Quality Measurement System for Excimer Lasers

Abstract

A beam quality measurement system for excimer lasers is developed. This system provides a 2-dimensional intensity distribution of an individual laser pulse delivered from an excimer laseroperated at a repetition rate of 250 Hz. The system is equipped with a large storage capacity of aframe memory which makes it possible to analyze the variation in intensity profiles of may successivepulses. The system is also equipped with the optics for measurements of far and near fieldpatterns and etalon fringe patterns. The beam qualities of a commercial excimer laser which hasan injection locking type configuration and practically measured with this system. The far andnear field patterns of a single laser pulse are presented. The pulse-to-pulse fluctuations of intensitypatterns and of total pulse energy are observed at various gas ages. The center of gravity ofsuccessive laser pulse patterns are traced with this system and the fluctuation of beam pointing isshown to increase with the gas aging.