| 摘要 |
An infrared imager includes an array of imager elements. Infrared radiation is focussed onto the array by a lens assembly including a plurality of lens elements. The imager array and the lens are within a cold box which includes an infrared-transparent window. For low noise, a spectrum-limiting filter is also located within the cold box, between the lens assembly and the window, at or within the pupil relief distance of the lens assembly. The pupil relief distance is extended by the use of at least one aspheric surface for one of the lens elements of the lens assembly. The mounting structure of the filter is the aperture stop for the infrared imager. The field of view may be reduced, if desired, without significant effect on the noise performance by use of a telescope including a second lens assembly optically identical to the first lens assembly, operated in conjunction with a confocal large-diameter lens assembly.
|
