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US 7,023,630 B2Granted
Optical element having minute periodic structure
AssigneeCanon Kabushiki Kaisha
InventorHiroshi Saito
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Abstract
An optical element is disclosed which is resistant to changes in environmental characteristics such as temperature and humidity and achieves a stable and favorable reflection suppressing effect. The optical element has a base member and a resin layer which is formed on the base member and has a linear expansion coefficient different from that of the base member. The resin layer has a minute periodic structure which has a period smaller than the wavelength of incident light on the optical element.
Claims10
An optical element comprising:
- a base member;
- and
- a resin layer which is formed on the base member and has a linear expansion coefficient different from a linear expansion coefficient of the base member,
- wherein the resin layer has a minute periodic structure which has a period smaller than a wavelength of incident light on the optical element,
- wherein the resin layer has an aspherical surface on which the minute periodic structure is formed, and
- wherein the following condition is satisfied:
- 20°<θ<90°,
- where, when R represents an approximate radius of curvature of the aspherical surface in the resin layer, θ represents an angle between effective maximum peripheral portions of the optical element, which is viewed from a center of the approximate radius of curvature R, and the approximate radius of curvature refers to a radius of curvature of a circle defined by a center of the aspherical surface and the effective maximum peripheral portions.
5 more elements
Dependencies are inferred from the claim text.