Shortwave infrared camera with extended spectral sensitivity

Abstract

The shortwave infrared spectral range (SWIR) has certain advantages for the observation during day under fog and haze weather conditions. Due to the longer wavelength compared to the visible spectrum the range performances in the SWIR is here considerably extended. In addition cooled SWIR focal plane arrays reach in the meantime sensitivities to be useable for night viewing under twilight or moon light conditions. The presented SWIR camera system combines the color imaging in the visible spectrum with the imaging in the SWIR spectrum. The 20x zoom optics is fully corrected between 440 nm and 1700 nm. A dichroic beam splitter projects the visible spectrum on a color chip with HDTV resolution and the SWIR spectrum on a 640x512 InGaAs focal plane array. The open architecture of the camera system allows the use of different SWIR sensors and CMOS sensors. A universal designed interface electronic operates the used cameras and provides standard video outputs and compressed video streams on an ethernet interface. The camera system is designed to be integrated in various stabilized platforms. The camera concept is described and the comparison with pure SWIR or combined SWIR / MWIR dual band cameras are discussed from an application and system point of view.