Issues

Military uses have given way to a wide range of general applications with the development, since the 1940's, of polycrystalline‐film and, later, single‐crystal infrared photon detectors.

Silicon photodiodes, particularly those of the avalanche type, offer speed, efficiency, sensitivity and reliability—both for the systems now in development and future ones at longer wavelengths.

Sophisticated fabrication techniques have made it possible to create these new detectors for photons—and other radiations—with good time resolution and low noise, and with special advantages for imaging.

Devices either of lithium‐drifted germanium or the more recently developed high‐purity type find uses in such fields as nuclear and exotic‐atom studies, nuclear medicine and activation analysis.