Low Noise Proximity Focused Image Intensifiers

Publisher Summary This chapter describes the low noise proximity focused image intensifiers. The performance of image intensifiers is often rated in terms of the capability to increase detection and recognition ranges at low light levels. Several models exist in which detection or recognition ranges for a given target, background and light level are related to objectively measurable tube parameters. To gain more insight into the parameters that affect the noise figure, a formula can be derived. For the derivation, the electron multiplication process is divided into two parts, the first collision of the electrons with the channel walls, and the rest of the multiplication process. It is assumed that the secondary emission process can be described by Polya statistics. It has been shown experimentally that by pulse saturation of the microchannel plate (MCP) a gain noise figure of 1.06 can be obtained, but these values could not be reproduced in a tube. It is found that by evaporating materials of a high secondary emission coefficient into channels of the MCP, gain noise figures as low as 1.15 were measured.