Compact multichannel infrared camera integrated in an operational detector dewar cooler assembly.

We present an ultracompact infrared cryogenic camera integrated inside a standard Sofradir's detector dewar cooler assembly (DDCA) whose field of view is equal to 120°. The multichannel optical architecture produces four nonredundant images on a single SCORPIO detector with a pixel pitch of 15 μm. This ultraminiaturized optical system brings a very low additional optical and mechanical mass to be cooled in the DDCA: the cool-down time is comparable to an equivalent DDCA without an imagery function. Limiting the number of channels is necessary to keep the highest number of resolved points in the final image. However, optical tolerances lead to irregular shifts between the channels. This paper discusses the limits of multichannel architectures. With an image-processing algorithm, the four images produced by the camera are combined to process a single full-resolution image with an equivalent sampling pitch equal to 7.5 μm. Experimental measurements on the modulation transfer function and noise equivalent temperature difference show that this camera achieves good optical performance.