Guest editorial

Fewer than ten years ago medical applications of lasers were rather limited as were the contributions of engineers. In contrast, during the past five years, there has been a rapid development of both pulsed and CW medical laser delivery systems. Engineering research and development has led to the clinical testing of pulse dye lasers for fragmentation of kidney stones, excimer lasers for reshaping of the cornea, pulse dye lasers for coagulation of enlarged blood vessels in the treatment of Port Wine Stain, and argon pulsed dye lasers for photodynamic treatment of cancer. More and more new medical applications for lasers rely upon the engineers¿ understanding of the interaction of laser light with tissue.In this special issue, papers are grouped into three catagories: optical interactions, thermal interactions, and application of opticalhhermal analysis.These papers illustrate the major advances in describing the optical and thermal interactions that have been made in the past five years. The ability to measure optical and thermal properties and to predict the response of tissue to laser light will foster a new generation of laser applications for medicine.