A method of reducing retro-repulsion of a stone during a laser lithotripsy procedure involves the use of a spacer tip or standoff sleeve to create a passage between the tip of a fiber and a stone, and to prevent collapse of a bubble formed by vaporization of and/or gas pressure on liquid present in the passage. The laser radiation may consist of continuous or quasi-continuous wave radiation that is relatively low in power compared to the therapeutic pulses, or may consist of the therapeutic pulses if the pulse frequency is high enough to prevent collapse of the bubble between pulses. The spacer tip or standoff sleeve further prevents collapse of the bubble and ingress of liquid into the laser path. The spacer tip or standoff sleeve may be a generally-cylindrical protective cap that is fitted to an end of the optical fiber and that extends beyond the fiber tip to provide a predetermined spacing or standoff between the fiber tip and the stone when the protective cap is in contact with the stone. Alternatively, the spacer tip or standoff sleeve may be a catheter sleeve that permits axial adjustment of fiber position within the sleeve.
