HOLOGRAPHIC VARIABLE ATTENUATORS FOR HIGH-POWER ND-YAG LASERS

Within the framework of the Eureka project EU-226: High Power Solid-St ate Lasers, we have investigated the possibility of making variable at tenuators for industrial Nd:YAG lasers using holographic optical eleme nts. Holographic variable attenuator (HVA) demonstrators were realized in fused silica for compatibility with multi-kilowatt Nd:YAG lasers. They were 40 mm long and 13 mm wide with transmission varying from 67% to 98%. Using two cascaded HVA, it was possible to vary the transmiss ion from 44% to 97% using a probe beam of 850 mu m. Moreover, no notic eable apodization was found on a 5-mm-diameter laser beam.