Characterization of excimer lasers for application to lenslet array homogenizers

We investigate the best method of characterizing high-divergence lasers, su ch as excimer lasers, to suppress fine-scale intensity nonuniformity that i s due to coherence effects of lenslet homogenizers. We show by a detailed a nalysis of the lenslet homogenizer that, for highest accuracy, a direct mea surement of the value of the autocorrelation function should be made at the separation p of the lenslet elements, identified as the critical spatial p eriod. We show that the commonly used characterization of lasers by the 1/e (2) width of the angular divergence is not the most accurate test and may o verstate or understate the effectiveness of a given laser. (C) 2001 Optical Society of America.