Optical system having a diffractive optical element, and optical apparatus

• US 6,825,979 B2
• Filed: 05/30/2002
• Issued: 11/30/2004
• Est. Priority Date: 03/08/2000
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Ogawa, Hideki
• Primary Examiner(s): Juba, Jr., John
• Application Number:
  US10/156,960
• Publication Number:
  US 20030053212A1
• Time in Patent Office: 915 Days
• Field of Search: 359/656, 359/566, 359/569, 359/570, 359/571, 359/576, 359/565
• US Class Current: 359/565
• CPC Class Codes: G02B 27/4211 correcting chromatic aberrations G02B27/0056, G02B27/4222, G02B27/4227 take precedence
• CPC Class Codes: G02B 5/1895 such optical elements having dioptric power

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.

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 a sign of the curvature of the lens surface having said diffraction grating provided thereon is the same as a sign of a focal length, in a design wavelength, of a system composed of, in said optical system, a surface disposed nearest to a front side to a surface disposed immediately before the lens surface having said diffraction grating thereon, and is different from a 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 the following condition is satisfied;

2. An optical system according to claim 1, wherein said optical system satisfies the following condition:

3. An optical system according to claim 1, wherein said optical system satisfies the following condition:

4. An optical system according to claim 1, wherein said diffraction grating is a laminated diffraction grating.

5. An optical system according to claim 4, 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.

6. An optical apparatus comprising an optical system according to claim 5, 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 air layer,

wherein said optical apparatus is selected from the group of optical apparatuses consisting of an image pickup apparatus, a film camera, a video camera, a digital camera, an observation apparatus, a telescope, a binocular, a projection exposure apparatus, and a stepper for manufacturing a semiconductor device.

7. An optical system according to claim 5, wherein each of said two diffraction gratings of said adjacently-laminated diffraction grating are formed with ultraviolet-curable plastic.

8. An optical system according to claim 1, wherein said diffraction grating is a blazed-type diffraction grating.

9. An optical apparatus comprising:

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 a sign of the curvature of the lens surface having said diffraction grating provided thereon is the same as a sign of a focal length, in a design wavelength, of a system composed of, in said optical system, a surface disposed nearest to a front side to a surface disposed immediately before the lens surface having said diffraction grating thereon, and is different from a 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 the following condition is satisfied;

10. An optical apparatus according to claim 9, wherein said optical apparatus is selected from the group of optical apparatuses consisting of an image pickup apparatus, a film camera, a video camera, a digital camera, an observation apparatus, a telescope, a binocular, a projection exposure apparatus, and a stepper for manufacturing a semiconductor device.

11. 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 a sign of the curvature of the lens surface having said diffraction grating provided thereon is the same as a sign of a focal length, in a design wavelength, of a system composed of, in said optical system, a surface disposed nearest to a front side to a surface disposed immediately before the lens surface having said diffraction grating thereon, and is different from a 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 an apex of an imaginary cone formed by extending a non-effective surface of said diffraction grating is located adjacent to the center of curvature of the lens surface having said diffraction grating provided thereon,

wherein said diffraction grating is a laminated diffraction grating, and

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.

12. An optical system according to claim 11, wherein each of said two diffraction gratings of said adjacently-laminated diffraction grating are formed with ultraviolet-curable plastic.

13. An optical apparatus, comprising:

an optical system according to claim 11.

14. An optical apparatus according to claim 13, wherein said optical apparatus is selected from the group of optical apparatuses consisting of an image pickup apparatus, a film camera, a video camera, a digital camera, an observation apparatus, a telescope, a binocular, a projection exposure apparatus, and a stepper for manufacturing a semiconductor device.

15. An optical apparatus according to claim 14, 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 air layer.

16. 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 a sign of the curvature of the lens surface having said diffraction grating provided thereon is the same as a sign of a focal length, in a design wavelength, of a system composed of, in said optical system, a surface disposed nearest to a front side to a surface disposed immediately before the lens surface having said diffraction grating thereon, and is different from a 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 the following condition is satisfied;