THERMAL-LENS MEASUREMENT OF A QUASI-STEADY-STATE REPETITIVELY FLASHLAMP-PUMPED CR, TM, HO-YAG LASER

A simple technique using cavity stability conditions is demonstrated t o measure the effective dynamic thermal lensing of a flashlamp-pumped Cr, Tm, Ho:YAG laser operated in a low repetition-rate regime of 4-7 H z. By measuring the flashlamp energy where a stable resonator becomes unstable, the effective focal length of the laser rod can be calculate d. When no mode restricting aperture is used in the cavity, the therma l lens behaviour displays a significant deviation from the commonly as sumed thin lens approximation. (C) 1998 Elsevier Science Ltd. All righ ts reserved.