A commercial model of an optically pumped, pulsed, Er:YAG solid-state laser will be modified and tested for beam performance and used in conjunction with a compatible low-loss, flexible, nontoxic, fluoride glass delivery fiber to study in vitro tissue interaction effects. The laser operates at an approximate wavelength of 2.94 lam on the 4I11/2 r 4I13l2 transition of trivalent erbium. Tissue mterachon studies at this wavelength, which falls at the peak of the strong infrared-absorption band of water, have demonstrated efficient, ablative-type cutting with minimal thermal damage to surrounding areas. Optimization and refinement of the laser-tissue interaction, in particular as a function of pulse energy and temporal profile, are now required. Initial, direct-focused beam experiments are proposed, to be followed by testing of commercially available zirconium-fluoride glass fibers for laser damage and for efficacy in contact tissue machining in vitro in a wet field.Favorable results will qualify the system for endoscopic applications in general laser surgery and, in particular, for catheter-guided angioplasty in peripheral and coronary vessels. The exacting requirements for removal of plaque in these latter applications demand precision cutting, and the Er:YAG laser would appear to be unique in its ability to provide this interaction via a flexible fiber.National Heart, Lung, and Blood Institute (NHLBI)
