Flexible beam guiding in a microsurgical UV laser scalpel

Many potential microsurgical applications of UV laser radiation need a flexible beam guiding system. Especially for the argon fluorine excimer laser-(λ = 193 nm) and for the 5^th harmonic of the Nd:YAG laser (λ=213 nm) the use of optical fused silica fibers is difficult. In this work we designed and tested a laboratory prototype of a scalpel for surgical treatments of the retina based on UV laser ablation. To achieve the necessary flexibility and to provide laser fluences above the ablation threshold of retina we developed a new type of beam guiding device. A hollow core waveguide is used in combination with a short length of a special fused silica optical fiber to guide the laser beam. To increase the laser fluence at the distal scalpel tip and to achieve a very small cut width a fused silica fiber (core diameter 600 μm) has been tapered down to a diameter of about 150 μm. We discuss some details of the UV laser beam guiding and show the first results of laser cutting experiments.