Infrared (IR) detectors fall into two main categories, thermal and
photon. The earliest detectors of IR were thermal in nature, e.g.
thermometers. The subsequent developments of these detectors, such as
thermopiles, resistance bolometers, Golay cells and pyroelectric
detectors, can operate at ambient temperature but have disadvantages of
insensitivity and slowness. A wide variety of semiconductor photon
detectors have been developed and these possess very high sensitivity,
high frequency response but have the disadvantage of needing cryogenic
cooling, particularly at longer wavelengths. In the main, the
applications have been in the military sphere, but widespread industrial
and scientific applications also exist. The majority of development
funding for these semiconducting IR detectors has, however, come from
military sources. This book is an attempt to provide an up-to-date view
of the various IR detector/emitter materials systems currently in use or
being actively researched. The book is aimed at newcomers to the field
and at those already working in the IR industry. It is hoped that the
former will find the book readable both as an introductory text and as a
useful guide to the literature. Workers in one of the various IR areas
will, hopefully, find the book useful in bringing them up-to-date with
other, sometimes competing, technologies. To both groups of readers we
trust that the book will prove interesting, thought-provoking and a spur
to further progress in this fascinating and challenging field of
endeavour.
