1 Introduction

Confocal microscopes have been built and used in research laboratories since the early 1980s and have been commercially available for only the last few years. The concept of the confocal microscope, however, is almost 50 years old. In 1957, Marvin Minsky [1] applied for a patent on the confocal idea. At that time, Minsky demonstrated great insight into the power of the confocal microscope. He realized that the design of the confocal microscope would give increased resolution and increased depth discrimination ability over conventional microscopes. Independently, in Czechoslovakia, M. Petr~n and M. Hadravsky [2] developed the idea for the tandem scanning optical microscope (a form of the confocal micro- scope) in the mid-1960s. However it was not until the 1980s, that the confocal microscope became a useful tool in the scientific community. At the time the confocal scope was introduced, the electron microscope was receiving a great deal of attention as it was becoming commercially available. Meanwhile, the confocal microscope required a very high intensity light source, and thus its commercialization was delayed until the emergence of affordable lasers in the technological market. Finally, without the aid of high-speed data processing equipment and large computer memories, taking advantage of the three-dimensional (3D) capabilities of the confocal microscope was not practical. Visualization of the data was also not feasible without high-powered computers and advanced...