Effect of coolant flow on the performance of round sapphire tips in a saline field

Round sapphire and silica tips have been studied as surgical probes for focusing Nd:YAG laser radiation during various surgical indications. Since most of these data have been obtained with silica tips from Surgical Laser Technology, there are limited data on the physical performance of round sapphire tips. An investigation of round sapphire tip performance during tissue ablation was undertaken. Nd:YAG laser power was delivered in repetitive 2-sec exposures to a round sapphire tip placed on fresh skinned chicken breast. Total exposures of 1,000 J were performed at different saline perfusion rates. The tip's performance in terms of tissue perforation rate, blanched tissue area, tissue heating rate, and forward transmission was measured. Best tip performance occurred at the lowest cooling rates and was independent of the tip's forward transmission value. No physical deterioration of the tip's optical surface was observed. Round sapphire tip performance in a saline field is primarily determined by the tip's temperature.