Accession Number:

AD0600168

Title:

IMPROVED LONG WAVELENGTH RESPONSE OF PHOTOEMISSIVE SURFACES.

Descriptive Note:

Technical documentary rept.

Corporate Author:

AIR FORCE AVIONICS LAB WRIGHT-PATTERSON AFB OHIO

Personal Author(s):

Report Date:

1964-04-01

Pagination or Media Count:

20.0

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

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE