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US 7,116,497 B2Granted
Retrofocus type optical system
AssigneeCanon Kabushiki Kaisha
InventorHiroshi Endo
Life of this patent
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Abstract
Provided is a retrofocus type optical system including a lens or a layer made of a material satisfying the following conditions of the Abbe constant νd and partial dispersion ratios θgd and θgF, νd<30, θgd<−3.333×10−3·νd+1.40, θgF<−2.615−10−3·νd+0.67. In the case that this layer is disposed on the front side of the aperture stop, the layer is designed to have a positive refractive power, and in the case that the layer is disposed on the rear side of the aperture stop, the layer is designed to have a negative refractive index.
Claims8
An optical system comprising:
- a refractive optical element composed of a solid material that satisfies the following conditions:
- νd<30
- θgd<−3.333×10−3·νd+1.40
- θgF<−2.615×10−3·νd+0.67
- where νd is the Abbe constant of the solid material, and θgd and θgF are partial dispersion ratios of the solid material,
- wherein, in the optical system, height from the optical axis of a point on the frontmost lens surface through which a paraxial marginal ray passes is smaller than the maximum value of heights from the optical axis of points on lens surfaces, on the rear side of an intersection P of the optical axis and a paraxial chief ray, through which the paraxial marginal ray passes, and
- in the case that the refractive optical element is disposed on the front side of the intersection P, the refractive optical element has a positive refractive power, and in the case that the refractive optical element is disposed on the rear side of the intersection P, the refractive optical element has a negative refractive power.
4 more elements
An optical system comprising:
- a refractive optical element composed of a solid material that satisfies the following conditions:
- νd<30
- θgd<−3.333×10−3·νd+1.40
- θgF<−2.615×10−3·νd+0.67
- where νd is the Abbe constant of the solid material, and θgd and θgF are partial dispersion ratios of the solid material;
- and
- an aperture stop,
- wherein, in the case that the refractive optical element is disposed on the front side of the aperture stop, the refractive optical element has a positive refractive power, and in the case that said refractive optical element is disposed on the rear side of the aperture stop, the refractive optical element has a negative refractive power, and
- the optical system satisfies the following condition:
- 2<OTL/f<15
- where OTL is the total optical length of the optical system, and f is the focal length of the optical system.
8 more elements
A retrofocus type optical system comprising:
- a refractive optical element composed of a solid material that satisfies the following conditions:
- νd<30
- θgd<−3.333×10−3·νd+1.40
- θgF<−2.615×10−3·νd+0.67
- where νd is the Abbe constant of the solid material, and θgd and θgF are partial dispersion ratios of the solid material;
- and
- an aperture stop,
- wherein, in the case that the refractive optical element is disposed on the front side of the aperture stop, the refractive optical element has a positive refractive power, and in the case that the refractive optical element is disposed on the rear side of the aperture stop, the refractive optical element has a negative refractive power.
5 more elements
Dependencies are inferred from the claim text.