Optical system having a diffractive optical element, and optical apparatus
First Claim
1. An optical system, comprising:
- a diffractive optical element having a diffraction grating provided, on a lens surface having curvature, in a concentric-circles shape rotationally-symmetrical with respect to an optical axis, wherein the sign of the curvature of the lens surface having said diffraction grating provided thereon is the same as the sign of a focal length, at a design wavelength, of a system lying between and including the surface disposed nearest to a front side and a surface disposed immediately before the lens surface having said diffraction grating provided thereon, and is different from the sign of a distance from the optical axis to a position where a center ray of an off-axial light flux enters the lens surface having said diffraction grating provided thereon, wherein diffraction grating is a laminated diffraction grating, wherein said laminated diffraction grating is an adjacently-laminated diffraction grating in which two diffraction gratings are disposed adjacent to each other across an air layer, wherein said adjacently-laminated diffraction grating is provided between two adjacent lens surfaces having substantially the same curvature, and is composed of three layers, including, in order from the front side, a first layer, a second layer and a third layer, said second layer being the thin air layer.
1 Assignment
0 Petitions
Accused Products
Abstract
An optical system includes a diffractive optical element having a diffraction grating provided, on a lens surface having a curvature, in a concentric-circles shape rotationally-symmetrical with respect to an optical axis. The sign of the curvature of the lens surface having the diffraction grating provided thereon is the same as the sign of a focal length, at a design wavelength, of a system composed of, in the optical system, a surface disposed nearest to an object side to a surface disposed immediately before the lens surface having the diffraction grating provided thereon, and is different from the sign of the distance from the optical axis to a position where the center ray of an off-axial light flux enters the lens surface having the diffraction grating provided thereon. Further, the apex of an imaginary cone formed by extending a non-effective surface of the diffraction grating is located adjacent to the center of curvature of the lens surface having the diffraction grating provided thereon.
71 Citations
8 Claims
-
1. An optical system, comprising:
-
a diffractive optical element having a diffraction grating provided, on a lens surface having curvature, in a concentric-circles shape rotationally-symmetrical with respect to an optical axis, wherein the sign of the curvature of the lens surface having said diffraction grating provided thereon is the same as the sign of a focal length, at a design wavelength, of a system lying between and including the surface disposed nearest to a front side and a surface disposed immediately before the lens surface having said diffraction grating provided thereon, and is different from the sign of a distance from the optical axis to a position where a center ray of an off-axial light flux enters the lens surface having said diffraction grating provided thereon, wherein diffraction grating is a laminated diffraction grating, wherein said laminated diffraction grating is an adjacently-laminated diffraction grating in which two diffraction gratings are disposed adjacent to each other across an air layer, wherein said adjacently-laminated diffraction grating is provided between two adjacent lens surfaces having substantially the same curvature, and is composed of three layers, including, in order from the front side, a first layer, a second layer and a third layer, said second layer being the thin air layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
-
-
4. An optical system according to claim 1, wherein said optical system satisfies the following condition:
-
5. An optical system according to claim 1, wherein said optical system satisfies the following condition:
-
6. An optical system according to claim 1, wherein each of the two diffraction gratings of said adjacently-laminated diffraction grating are formed with ultraviolet-curable plastic.
-
7. An optical system according to claim 1, wherein said diffraction grating is a blazed-type diffraction grating.
-
8. An optical apparatus, comprising:
an optical system according to claim 1.
Specification