IMPROVED LONG WAVELENGTH RESPONSE OF PHOTOEMISSIVE SURFACES.
Abstract
The usefulness of photoemitters as detectors for optical lasers is limited by their very poor quantum efficiency in the red and infrared portion of the spectrum. For example, the quantum sensitivity of the S-20 photosurface at 0.7 microns is approximately 0.25%. However, some 70% of the incident radiation at 0.7 microns is transmitted through the semi-transparent S-20 surface and is lost. In the experiment, the incident light from a monochromator was trapped by total internal reflection in the faceplate, resulting in multiple encounters of the light with the photocathode and, consequently, in a high degree of absorption by the cathode. Gains of three and five times the normal sensitivity of the S-20 photosurface at 0.7 micron were observed using this technique, depending on the polarization of the incident light. Curves showing the spectral dependence of this gain for both axes of polarization are presented. The internal reflection technique may be applied to any tube having a flat faceplate backed by a semi-transparent photocathode. However, any imaging capability of the tube is lost. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 01, 1964
- Accession Number
- AD0600168
Entities
People
- Bilyie E. Rambo
Organizations
- Air Force Research Laboratory