A binocular system for an image acquisition device comprises a pair of optical systems, each comprising an image sensor comprising an array of pixels including pixels sensitive to IR wavelengths for acquiring an image. A lens assembly includes a collecting lens surface with an optical axis, the lens assembly being arranged to focus IR light received from a given object distance on the sensor surface. The lens assembly includes at least a first reflective surface for reflecting collected light along an axis transverse to the optical axis so that a length of the optical system along the optical axis is reduced by comparison to a focal length of the lens assembly. Each optical system is disposed axially symmetrically about a central axis； and at least each collecting lens of the pair of optical systems is disposed about an optical axis extending away from the image sensor at an angle β to said central axis
