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US 7,031,078 B2Granted
Laminated diffractive optical element
AssigneeCanon Kabushiki Kaisha
InventorHideo Ukuda
Life of this patent
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Abstract
An optical element of which diffraction efficiency hardly varies with wavelength is provided by using an optical material satisfying the conditions that nd>−6.667×10−3νd+1.70 and θg,F≦−2×10−3νd+0.59 where nd is a refractive index at d-line, νd is an Abbe number at the d-line, and θg,F is a second order dispersion at d-line, whereby diffraction efficiency is improved in any working visible wavelength region and more precise chromatic aberration correction is obtained.
Claims10
A diffractive optical element assembly comprising:
- a first diffractive optical element having a surface formed into a diffractive shape;
- and
- a second diffractive optical element having a surface formed into a diffractive shape,
- wherein the first diffractive optical element is made of an optical material in which nd>−6.667×10−3νd+1.70 and θg,F≦−2×10−3νd+0.59, where nd is a refractive index at d-line, νd is an Abbe number at the d-line, and θg,F is a second order dispersion at d-line,
- wherein the second diffractive optical element has an Abbe number greater than that of the first diffractive optical element, and
- wherein the diffracting surface of the first diffractive optical element and the diffracting surface of the second diffractive optical element are arranged opposite each other.
3 more elements
A diffractive optical element assembly comprising:
- a first diffractive optical element having a surface formed into a diffractive shape;
- and
- a second diffractive optical element having a surface formed into a diffractive shape,
- wherein the first diffractive optical element is made of an optical material that comprises a polymer and an inorganic nanoparticle material, which reduces a second order dispersion of the first diffractive optical element,
- wherein the second diffractive optical element has an Abbe number greater than that of the first diffractive optical element, and
- wherein the diffracting surface of the first diffractive optical element and the diffracting surface of the second diffractive optical element are arranged opposite each other.
3 more elements
Dependencies are inferred from the claim text.