Miniature imaging photon detectors

An imaging photon detector has been developed for a number of research applications in geophysics and astrophysics. S20/S25 photocathodes provide sensitivity extending to the near-infrared, and a pair of microchannel plates (MCP), mounted in a chevron arrangement provide an electron gain of about 4*106. At a voltage difference of about 2.0 kV across the two MCPs, this gain is adequate to drive a proportional amplitude-sensing system based on a linear resistive anode, and a resolution of about 200 mu m can be obtained over an effective diameter of 20 mm. Over a limited range the resolution is inversely proportional to the gain, with a value of approximately 100 mu m for a gain of 2*107.