The photographic system with a semiconductor photodetector for visualization and recording of IR radiation

The possibility of increasing the spectral sensitivity of the photographic system with a Si:Zn semiconductor detector have been studied. The cooling p hotographic system is designed to extend the sensitivity of the photographi c system toward longer infrared wavelengths (up to 4 mum). The photodetecto r was irradiated on the back-side with infrared radiation in a particular w avelength range that was used to control the photoconductivity of the detec tor. The IR radiation excites the photosensitive semiconductor detector of the device thus controlling the current density and the visible light emiss ion from the gas discharge gap. Due to the cooling the dark current in the photodetector material is extremely decreased and the sensitivity with resp ect to the incoming infrared radiation is increased. The size of the discha rge gap d (70 mum) and the residual gas pressure p (70 Torr) are chosen to ensure a sufficiently bright light. The assesment of the image formation is then based on analysis of the discharge light emission, visualized by taki ng a photograph through the transparent anode plate. Expressions are obtain ed for the maximum photographic sensitivity.