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 to detect above the noise level.
These threshold characteristics define the most important tactical and
technical parameters of the entire optoelectronic system, such as its
range, resolution, precision. The threshold characteristics of
optoelectronic system depend on many of its components; all designers
agree, however, that the critically responsible part of the system is
the photodetector [1]. By the end of the 1960s the physicists and the
engineers were able to overcome many obstacles and to create
photodetectors (at least single-element or few-element ones) which
covered all the main optical bands (0. 4 . . . 2,2 . . . 3, 3 . . . 5,8
. . . 14 J. . Lm), carried out the detection almost without any loss
(the quantum yield being as high as 0. 7 . . . 0. 9), and reduced the
noise level to the lowest possible limit.