Power supply for an intensified night sight.

摘要

In an image intensifier night sight having a graticule illuminator, it is desirable that the brightness of the graticule should be maintained in proportion to the intensifier output image brightness so that the visibility of graticule and scene details are preserved. Such a sight comprises an image intensifier (2) having an image photocathode input (8) and an electron luminescent output image screen (12), a magnifier (3) for viewing the output image screen, a graticule injection system (5) for superposing a graticule (4) upon the output image screen, and a light source (14) for illuminating said graticule. In a power supply (15) for such a sight means (19) are provided for deriving a signal related to the brightness of the output image screen and for controlling the brightness of the light source in response to the signal to maintain the ratio between output screen and graticule brightnesses substantially constant.