Abstract: A passive millimeter-wave imaging system (10) is disclosed that provides a full 360° instantaneous azimuthal field-of-view (54) image of a scene. The imaging system (10) makes use of a spherical Luneburg lens (12) and a series of millimeter-wave direct detection receivers (24) configured in a ring (16) around the lens (12), and positioned at the focal plane of the lens (12). The series of receivers (24) are positioned on a plurality of consecutive sensor cards (14), where each card (14) includes a certain number of the receivers (24). The receivers (24) define a one-dimensional focal plane array with limited obscuration, and thus give a 360° instantaneous field-of-view (54) of a slice of the scene. Processing circuitry (32), including a multiplexing array interface for multiplexing the signals from the receivers (24), are positioned on an outer ring (34) outside of the sensor card ring (16).

Abstract: An anti-reflection coating for optical elements and a method for forming an anti-reflection coating on an optical element includes one or more layers of a woven plastic mesh material that may be layered on the surface of an optical element such as the lens and secured thereto with a suitable adhesiveor pressed on to the surface by either a peripheral retaining ring or bodily pressed in place by a low loss, low dielectric medium. The number and thickness of the layers of the woven plastic mesh material are selected to provide optimal reduction of reflection losses.