| 摘要 |
The method according to the invention is used to determine the displacement of the focal plane (9) which is caused by changes in air pressure or by changes in temperature in the case of lenses for high-resolution aerial photographic systems. The displacement can then be corrected by an adjusting movement of a lens element (2a). For this purpose, between the exposure operations a grid (7) arranged in the lens is exposed and projected in autocollimation via a partially mirrored surface (1) on the front side of the lens onto a detector (5) arranged in the film plane. This detector consists of a detector array which is inclined relative to the film plane (4) and comprises approx. 2000 elements. The output signal of the detector is modulated by the periodicity of the grid (7). The maximum of the modulation amplitude determines the point of intersection of the detector array (5) with the focal plane (9). Its offset (deviation) from the centre position is used to perform microprocessor-controlled fine adjustment of the adjustable lens element (2a). <IMAGE>
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