Patent ID: 7154650

Claim:
Scanning apparatus operable in the microwave, mm-wave and infrared ranges and comprising a support structure, a first reflective disc or mirror which is mounted in said support structure for rotation relative to the support structure about a first axis, a second reflective disc or mirror which is mounted in said support structure for rotation relative to the support structure about a second axis, the arrangement being such that radiation from a scene being scanned can reach a reflective surface of the first disc or mirror to be reflected thereby onto a reflective surface of the second disc or mirror, to be reflected by the latter, in turn, onto said reflective surface of the first disc or mirror again, to be reflected from the first disc or mirror into or onto a further part of the apparatus incorporating a receiver or receivers for such radiation, and wherein said reflective surface of the first disc or mirror has an axis of rotational symmetry tilted at a first small angle relative to said first axis and wherein said reflective surface of the second disc or mirror has an axis of rotational symmetry tilted at a second angle relative to said second axis, and driving means for said discs or mirrors arranged to drive these in respective opposite senses, the arrangement being such as to effect a substantially linear scan, the size of said second angle relative to said first angle being selected so as to reduce or eliminate pupil wander in the direction orthogonal to the direction of line scan.