Device for measuring light incident on an optical system
AssigneeCanon Kabushiki Kaisha
InventorsNoriyuki Nose, Kiyonobu Endo
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Abstract
A device for measuring light incident on an optical system comprises an optical system defining an optical path, a plurality of diffraction lattices arranged in the optical path, each of the diffraction lattices comprising a plurality of periodically arranged semireflecting oblique surfaces, and photodetector means for detecting each of the diffracted lights from the diffraction lattices distinctively. The diffraction lattices are each of different predetermined areas; however, when even light is input, each lattice diffracts the same total quantity of light to its respective detector.
Claims9
A device for measuring light incident on an image forming optical system, comprising:
- an image forming optical system defining an optical path;
- a beam splitter disposed in said optical path and having a plurality of diffraction lattices of different predetermined areas, each of said diffraction lattices providing, when even input light is incident on each of said diffraction lattices, substantially the same total quantity of diffracted light irrespective of the difference in the areas of the diffraction lattices;
- and
- light measuring means having photodetector means for receiving the diffracted light from said diffraction lattices.
Dependencies are inferred from the claim text.