Dual-wavelength camera for long-range reconnaissance platforms

Cameras for remote sensing and for long range reconnaissance on airborne and space platforms in the 0.4-1.0 μm region exist, but there is a growing need for images in longer IR wavelengths. In those wavelength regions, large apertures are essential to achieve satisfactory ground resolution but this conflicts with the limitations of weight often associated with long-range reconnaissance platforms. The high costs of the system itself and of its installation on the platform make it advantageous to provide both wavelength bands in a single instrument. A dual-waveband airborne telescope and camera system has been developed by El-Op Ltd. which will provide high-resolution images in the thermal IR at night and in the visible in daylight, or both simultaneously. It offers low weight, compact size and high dimensional stability over a wide range of environmental conditions. The two detector arrays are mounted in a compact focal plane assembly with a spectral beam-splitting system that optimizes the transmittance of each band. A cooled IR detector is essential to achieve the necessary sensitivity and a special detector array with a high reliability, lightweight, low power cooling unit has been developed.