The design of optical coatings

Abstract

Optical coatings1 are stratified media that encourage interaction amongst many diverse properties, the principal ones being the intrinsic optical properties and optical interference. Optical coatings may range from simple antireflection coatings to dispersion controllers in ultrafast pulse systems, or from solar control coatings to optical data storage media. They may even be used as optical switches. Their principal role may be the modification of the optical properties of a surface or they may be important devices in their own right. Although the properties and applications of coatings are wide ranging nevertheless there are important common features both in the makeup of coatings and in their principles of operation. The design of optical coatings, the topic of this paper, is essentially the control of complicated interference to achieve desired optical effects and it is being helped considerably by new tools, many of which are derived from the current impressive advances in computing power. In spite of the new tools, however, there continue to be very difficult, perhaps intractable, problems. Some of these have been with us for a long time. An obvious question is whether or not the optical coating designer is gradually being made redundant but an inadequacy of completely automatic design methods when coating complexity increases beyond a certain point implies the need for continuing understanding, knowledge, experience, and skill.