Introduction

Lasers were žrst demonstrated in the 1950s in the microwave region of the electromagnetic spectrum, and this subset of lasers was called a MASER (Microwave Ampližed by Stimulated Emission of Radiation). By 1964 most of the lasers that we know today had already been conceived, but it took many more years for lasers to be accepted into industrial environments. One reason is that early lasers were highly unreliable, but possibly just as important was the fact that lasers were solutions to problems that nobody, at that time, knew existed.