SSC09-III-5 Compact Dual Field-of-View Telescope for Small Satellite Payloads

Small satellite payloads commonly involve missions with multiple field-of-view (FOV) capability. For these missions, it is often desirable that the payload instrument contain optical sensors with both a wide FOV for searching or scanning a scene and a narrow FOV to interrogate and identify the object of interest. This generally requires multiple sensors or a zoom lens with multiple moving lenses. For infrared sensors, these approaches are generally not compact enough for use on small space platforms, unmanned air vehicles, or small satellite payloads. This paper describes a compact dual field-of-view telescope with a 6x field ratio. The selection of the field involves changing optical filters, which transmit different spectral wavebands. Each spectral waveband is associated with separate optical paths with differing focal lengths, thus fields-of-view. This concept has been proven through the design, build, and alignment of a long-wave infrared (LWIR) catadioptric telescope.