| 摘要 |
The invention relates to a Fresnel focusing screen for SR cameras, whose Fresnel structure is situated between the camera lens and viewfinder image plane, by means of which the viewfinder image curvature is removed and an optimum viewfinder image illumination is simultaneously ensured. The Fresnel structure remains invisible to the greatest possible extent in this arrangement. This aim is attained through splitting the refractive power of the focusing screen by arranging that each of the surfaces of the focusing screen, which are provided with different structures, delivers a specific portion of the refractive power. It is advantageous to provide the surface, which serves simultaneously as focusing plane, with directionally oriented raster structures, for example with cylindrical ring microraster structures and wedge flank slopes defined on one side.
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