There has been a tremendous increase in interest in optical interferometry during the last twenty years, a period in which the subject has undergone a complete transfor- mation. The main reason for this is, of course, the development of the laser which made available, for the first time, an intense source of coherent light. Another reason has been the increasing use of digital computers to process the data obtained from an interferometer. A third reason is the availability of single-mode optical fibers which can be used to provide an optical path several metres long, with very low noise, in an extremely small space. As a result of these advances, optical interferometry is finding a remarkably wide range of applications.
The aim of this book is to present a self-contained treatment of this subject with particular emphasis on recent developments and their implications for the future. A brief historical survey leads up to three chapters covering the classical concepts of two-beam interference, coherence and multiple-beam interference. Chapter 5 then discusses interference in thin films, antireflection coatings and interference filters.
As mentioned at the outset, lasers are now being used to an increasing extent in optical interferometry; in fact, this has led to the virtual demise of the classical mercury arc. Accordingly, Chapter 6 looks at the laser as a light source and discusses techniques for obtaining a single-frequency output and for frequency stabilization.