Generation III image intensifiers use an aluminum gallium arsenide/gallium arsenide (AlGaAs/GaAs) heterostructure photocathode that typically sensitive to light in the wavelength range of 550-900 nm. The possibility of improving the performance of Generation III night viewing devices by extending the spectral response into the blue (less than 550 nm) region of the electromagnetic spectrum has stimulated considerable interest lately. This is largely due to the fact that an increase in the blue response of the image tube significantly increases detection, recognition, and identification of targets in sandy or desert terrain. The short wavelength response of the Generation III image tube is primarily dominated by the thickness and composition of the AlGaAs window and the thickness of the GaAs active layer. In this paper, we review the role of the AlGaAs layer to the overall performance of the Gen III image tube and discuss the optical properties of the AlGaAs/GaAs heterostructure. Finally, the overall performance of blue enhanced photocathodes is discussed with data presented on sealed tubes with quantum efficiencies greater than 20% at 500 nm.

Date Published: 8 September 1995
PDF: 5 pages
Proc. SPIE 2551, Photoelectronic Detectors, Cameras, and Systems, (8 September 1995); doi: 10.1117/12.218624

Published in SPIE Proceedings Vol. 2551:
Photoelectronic Detectors, Cameras, and Systems
C. Bruce Johnson; Ervin J. Fenyves, Editor(s)