Limitations in Optical Imaging Devices at Low Light Levels

Abstract

An examination is made of the influence of objective lens parameters on the resolution capabilities of low light level imaging devices. From the resulting characteristics the dependence of the perception range of a given target on the incident light level is deduced. The restrictions imposed by larger lenses on the depth of field of acceptable focus are investigated, and comparisons made with the thresholds set by quantum-noise and optical resolution limitations. Degradations in the performance of image intensifiers due to different levels of image tube dark noise are also discussed.