Laser technology: Theory and operating principles: Application of the principles of quantum electronics has yielded hundreds of lasers whose wavelengths span from the infrared to the X-ray region of the spectrum

This month marks the 25th anniversary of the discovery of the laser. In the quarter century since Theodore H. Maiman first produced a beam of deep red light from a ruby rod, intensive research has yielded literally hundreds of lasers whose wavelengths now span the electromagnetic spectrum from the infrared region to the threshold of the X-ray region. The impact of lasers and of quantum electronics — the area to which the laser gave impetus — on scientific research is best attested to by the six Nobel laureates that the field has produced. However, the laser is no longer the sole domain of the physicist or the chemist, but has moved in a dramatic way into the factory, the hospital, and the home. This is reflected by the rapidly expanding laser market. Since the 1962 introduction of the first commercial laser, the sales of lasers and laser systems have grown steadily, peaking at 1984's record level of $4.4 billion, according to Laser Focus magazine's annual market survey. This article presents a brief overview of the theory and operation of the laser and discusses several of its most prominent applications. In-depth coverage of selected topics is presented in accompanying articles.