THERE IS much to interest the physician in the development of that fascinating instrument of modern physics, the laser. Although the first working laser was produced as late as July, 1960,1laser development is now one of the greatest research fields of modern science. However, except for a few exceptions in the biomedical and microwelding fields, it remains a laboratory tool for scientific research. It is to medicine that most research workers in laser technology look for immediate practical developments, although up to the present there has not been much investigation of lasers in the field of medicine. The laser produces a beam of coherent electromagnetic radiation of a sharply defined wavelength in that region of the spectrum broadly described as optical. This range includes the near-violet, the visible, and the near and far regions in the infrared. The term "coherence" is to be emphasized because it is an