This invention relates to enhancement of the delivery of laser beams to internal surgical sites by employing, where practical, heavy water rather than normal water as both the irrigation fluid and the laser beam transmission medium that fills some or all of the space between the distal tip of the optical fiber to the surgical site. The use of heavy water is advantageous for surgical procedures employing lasers operating in the wavelength range of 1.0 microns to 2.5 microns where heavy water is substantially more transparent than normal water. This range includes the commercially important semiconductor diode laser operating at 1.47 microns where the optical attenuation coefficient in heavy water is less than one hundredth of that in normal water. Due to the rather high cost of heavy water, methods are described for collecting and re-cycling heavy water used during laser surgery to mitigate this cost.
