Apodizing induced-absorption apertures with a large optical beam diameter and their application in high-power 1.06 μ laser systems

Soft apodizing apertures were developed and investigated. They were based on the absorption induced in CaF₂:Pr by ionizing radiation and their diameters were 2–5 cm. The transmission profiles of the apertures were determined at the wavelength of 1.06 μ. The optical quality of the apertures was determined, measurements were made of the damage thresholds and their use in high-power laser systems was studied. The damage threshold of CaF₂:Pr apertures in focused laser beams was higher than the damage thresholds of laser glasses and these apertures did not bleach right up to the damage threshold. An increase in the efficiency of conversion to the second harmonic was observed when a soft aperture was placed in a laser beam.