Filter for compensation of the brightness fall-off in the image plane of a lens

The invention relates to a filter for compensation of the brightness fall-off in the image plane of a lens with a predetermined course of the transmission T (w), which depends on the image angle omega , the filter having a central circular region with a constant transmission value. For a filter, in...

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Bibliographic Details
Main Author KUTTNER,PAUL,.DR
Format Patent
LanguageEnglish
German
Published 11.05.1988
Edition4
Subjects
OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
OPTICS
PHYSICS
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Summary:The invention relates to a filter for compensation of the brightness fall-off in the image plane of a lens with a predetermined course of the transmission T (w), which depends on the image angle omega , the filter having a central circular region with a constant transmission value. For a filter, in which the diffraction phenomena impairing the image quality can be avoided and which nevertheless can be manufactured in an easy and economical manner, it is proposed that the filter has, concentrically with the central circular region, one or more annular zones. In this case, the transmission within a zone has essentially a constant value. The radial extent and the transmission value of each zone are dimensioned in such a manner that at every point of the filter the amount of the difference between the transmission value fixed for this point by the equation T (w) and the transmission value of the associated zone always lies below a predetermined limit value g.
Bibliography:Application Number: DE19863636684