This book is addressed to designers of photodetectors and photodetecting systems, designers of focal plane arrays, charge-coupled devices, specialists in IR technologies, designers of optoelectronic detecting, guiding and tracking systems, systems for IR direction finders, lidars, lightwave communication systems, IR imagers. All these specialists are united by one common purpose: they are all striving to catch the weakest possible optical signal. The most important characteristic of photosensitive devices is their detectivity, which determines the lowest level of optical signal they are able...