Pulsed HF laser radiation transmission through fluorocarbon polymer coated silver hollow glass waveguides

Flexible fluorocarbon polymer - coated silver hollow glass waveguides, devised for the delivery of 3.0 mu m radiation, were evaluated using a plasma cathode HF laser emitting at 2.78 mu m, in a 180 ns duration, st a I Hz repetition rate. A multimode beam of 10 mrad divergence at FWHM, was focused into the 700 mu m diameter, 986 mm long waveguide and was transmitted through it under straight and various bent conditions. The straight transmission loss was found to be 0.9 dB/m, while the bent transmission losses varied from 2.0 dB/m (90 degrees bent - 35 cm bending radius) to 2.4 dB/m (180 degrees bent - 10 cm bending radius), for the range of measurements attempted. Transmission as a function of the laser energy input was also measured. Losses increased from 1.5 dB/m at 3 mJoules to 7.0 dB/m at 20 mJoules laser input. These attenuation characteristics at the wavelength of 2.78 mu m make these waveguides very promising for pulsed radiation and tissue interactions in in vitro and in vivo trials.