Image intensity degradation tester

摘要

A tester for image intensifier tubes used in night vision goggles used by aircraft crew members includes a photosensor, dc. power supply, lamp, optical filter, neutral density optical filters, feedback control, and columnating lens. The intensity of the lamp is controlled with reference to the magnitude of an electrical variable that changes with the intensity of light produced by the lamp. A differential amplifier having a constant current bridge circuit varies base current to cascaded transistor amplifiers in accordance with changes in the electrical variable. The bridge and amplifier stages stabilize the intensity of light produced by the lamp. An array of optic filters of graduated intensity shows the intensity of light in a range of wavelengths near infrared able to pass through an ANVIS filter.