| 摘要 |
<p>An infrared radiation detecting system comprises an optical imaging system (25) for receiving radiation from a field of view (23) and delivering that radiation to an image surface (16). A background limited detector unit (26) having a detecting surface ( phi ) located in a cold shield housing having a cooled aperture (13) is spaced from image surface (16) and a transfer lens system (24) is interposed to transfer infrared radiation therebetween. Lens system (24) is arranged to focus the radiation at the detecting surface ( phi ) of the detector unit (26) such that the focussed radiation field curvature coincides with the physical curvature of detecting surface ( phi ), to form a pupil which is coincident in space with the position of the cooled aperture (13) and to dimension the pupil to match the dimension of the cooled aperture (13). To achieve these effects the transfer lens system (24) is formed by four lens elements (A,B,C,D) of selected power, axial spacing, and refractive surface curvature.</p> |
