Abstract

For selective photocoagulation in ophthalmology μs-laser pulse durations with pulse energies of some millijoules at a repetition rate of 500Hz in the green spectral range are required. A suitable solid state laser medium to achieve Q-switched pulse durations of some hundred ns is Nd:YLF due to its low stimulated emission cross section. In order to further extend the pulse duration high efficient intracavity SHG is applied. A 60mm long and 4mm in diameter c-cut Nd:YLF-laser rod is transversally pumped by three elements of four laser diodes. Intracavity frequency doubling is realised by noncritical and TypI critical phasematching with LBO and TypII critical phasematching with KTP. The system is Q-switched with a repetition rate of 500Hz. In order to investigate pulse lengthening, two different methods using acusto-optical or electro-optical Q-switches are used.

© 2000 IEEE