Diffractive optical element and photographic optical system having the same
First Claim
1. A photographic optical system comprising a diffractive optical element having a grating structure in which a plurality of diffraction gratings made from at least two kinds of materials different in dispersion from each other are laminated, and a maximum optical path length difference in the grating structure being m times the design wavelength for each of the design wavelengths, where m is a design order of diffraction, said diffractive optical element satisfies the following conditions for the design wavelengths λ
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Accused Products
Abstract
To obtain a diffractive optical element of high diffraction efficiency over a wide range of wavelengths with no conspicuous color flare and a photographic optical system having the diffractive optical element, at least two diffraction gratings of different materials in dispersion are stratified, the first order is chosen as the design order and two wavelengths which, when multiplied one times, amounts to the maximum optical path length difference in the grating structure are used as the design wavelengths, wherein each of the values of the plurality of design wavelengths is determined so as to make white or nearly white flare caused by the diffracted light in the zero and second orders.
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Citations
10 Claims
- 1. A photographic optical system comprising a diffractive optical element having a grating structure in which a plurality of diffraction gratings made from at least two kinds of materials different in dispersion from each other are laminated, and a maximum optical path length difference in the grating structure being m times the design wavelength for each of the design wavelengths, where m is a design order of diffraction, said diffractive optical element satisfies the following conditions for the design wavelengths λ
Specification