Electron-Beam Apparatus for Testing Lwir Detectors in a Cryogenically Shielded Environment

A Scanning Electron Microscope (SEM) has been modified to probe infrared detectors operating in a cryogenically shielded environment. A reduced infrared photon background is obtained by incorporating the SEM objective aperture as part of a liquid helium cooled radiation shield which surrounds the device under test. Use of this equipment will facilitate determination of the response mechanisms of long wavelength detectors to ionizing radiation.