Laser oscillator as well as the evaluation device etalon and etalon evaluation method

摘要

PROBLEM TO BE SOLVED: To correctly measure the evenness in gap intervals due to positions thereof, by a method wherein optical elements changeable of the irradiating region of irradiating beams are arranged between an excimer laser beam source and an etalon in order to irradiate the etalon with the laser beams from the excimer laser beam source. ;SOLUTION: A slit 14 having a rotary mechanism 15 is inserted right before an etalon 16 as an objective measured element. Besides, the fluctuation 21 in the gap intervals of the etalon 16 is computed from the signals 19 of a sensor 18 using a computer 20. In order to measure the evenness in the gap intervals due to positions, the slit 14 is turned to record the signals 19 in respective positions for computing the half value widths in the transmission characteristic. In such a constitution, the difference in the gap intervals is reflected in the difference between the minimum and maximum half value widths, thereby enabling the difference in the gap intervals to be measured based on the difference in the half value widths. Accordingly, the evenness in the gap intervals can be evaluated without fail.;COPYRIGHT: (C)1999,JPO