Multispectral thin film coating on infrared detector

Abstract

High end applications in infrared may benefit from infrared colorimetry. Actual systems are designed using filter wheel, gratings or dichroic components. Those systems are bulky, do not allow real-time acquisition and are sensitive to stray light. Sagem & Reosc recently developed technologies to pixelate infrared coating filters at detector level. It allows designing very compact systems, easy to cool down and to significantly reduce ghost images. Optical systems are simplified and can achieve fast acquisition of multi-spectral video. Numerical simulations have been performed in order to quantify the pattern shape influence on the optical performances at the microscopic scale. The etching processes of multilayer stacks have been developed. Finally, prototypes have been manufactured and tested. This technology opens up new perspectives in the field of infrared filtering.