Passive energy diametric scanner

Abstract

Diametric scanning of a forward target region, wherein each scan line proceeds from an edge of a circular field of view through the center to the opposite edge while the scan angle is advancing. Processing of line scan data for target acquisition and tracking is facilitated by rotational translation, since each successive diametrically-scanned line is incrementally related to the previous line. Scanning progresses uniformly and continuously. An optical path between a target area and an energy sensor is intercepted by a first angled reflector of a dual reflector assembly, rotating around the optical path axis as part of a rotor having a peripheral ring with a single gap. Rotating about the axis is a ring fitted with an array of reflecting facets. The energy beam is redirected by a first reflector of the dual reflector assembly through the gap and reflected by a facet moving past the gap and thence to the sensor via a second angled reflector. In one embodiment, curvature of the reflective surface on each facet results in repetitive displacement of the targeted object point in the field of view, scanning the field of view in a rotating pattern of diametric scan lines while keeping the image of the targeted object point focused on the sensor. In another embodiment, elementary-sized facets on the facet ring scan the first image diametrically as it rotates within the gap. The resultant intensity modulation of the reflected and redirected beam is detected.