Optical system, and image pick-up apparatus using the same

• US 20050168807A1
• Filed: 01/24/2005
• Published: 08/04/2005
• Est. Priority Date: 01/30/2004
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Endo, Hiroshi
• Granted Patent: US 7,206,126 B2
• Time in Patent Office: Days
• US Class Current: 359/354
• CPC Class Codes: G02B 15/144511 arranged -+-+
• CPC Class Codes: G02B 15/1461 the first group being positive
• CPC Class Codes: G02B 27/0037 with diffracting elements G02B27/0056 takes precedence; holographic optical elements G02B5/32; zone systems G02B5/1876
• CPC Class Codes: G02B 27/4211 correcting chromatic aberrations G02B27/0056, G02B27/4222, G02B27/4227 take precedence

Abstract

An optical system including a diffractive optical element, and an optical member for suppressing incidence of ultraviolet radiation on the diffractive optical element is disclosed. The optical member is disposed on a light incident side of the diffractive optical element. The optical member has optical power to achieve an optical system that has high optical performance and preferable environmental durability.

Claims

1. An optical system comprising:

a diffractive optical element; and

an optical member for suppressing incidence of ultraviolet radiation on the diffractive optical element, the optical member being disposed on light incident side of the diffractive optical element,

wherein a conditional expression, 0.1<

|fu|/f<

2, is satisfied, where fu and f represent focal lengths of the optical member and the entire optical system, respectively.

2. An optical system according to claim 1, wherein said optical member includes ultraviolet-radiation cut coating.

3. An optical system according to claim 1, wherein said diffractive optical element includes a diffraction grating made of ultraviolet-radiation curing resin.

4. An optical system according to claim 1, wherein said diffractive optical element and said optical member are spaced from each other with air therebetween.

5. An optical system according to claim 1, wherein said diffractive optical element and said optical member are cemented on each other.

6. An optical system according to claim 1, wherein a conditional expression, 10<

|fd|/f<

100, is satisfied, where fd represents a focal length of diffraction function of said diffractive optical element.

7. An optical system according to claim 1,

wherein the optical system is a zoom lens including a plurality of lens units;

wherein each interval between the respective lens units is changed during zooming; and

wherein said diffractive optical element and said optical member are included in a lens unit.

8. An optical system according to claim 1,

wherein the optical system is a zoom lens including, in order from an object side to an image side, a first lens unit having positive optical power, a second lens unit having negative optical power, a third lens unit having positive optical power, a fourth lens unit having negative optical power, a fifth lens unit having positive optical power, and a sixth lens unit having negative optical power;

wherein each interval between the respective lens units is changed during zooming; and

wherein said diffractive optical element and said optical member are included in the first lens unit.

9. An optical system according to claim 1,

wherein the optical system is a zoom lens including, in order from an object side to an image side, a first lens unit having negative optical power, and a second lens unit having positive optical power;

wherein an interval between the respective lens units is changed during zooming; and

wherein said diffractive optical element and said optical member are included in the second lens unit.

10. An optical system according to claim 1,

wherein the optical system is a zoom lens including, in order from an object side to an image side, a first lens unit having negative optical power, a second lens unit having positive optical power, and a third lens unit having negative optical power;

wherein each interval between the respective lens units is changed during zooming; and

wherein said diffractive optical element and said optical member are included in the second lens unit.

11. An optical system according to claim 1,

wherein the optical system is a zoom lens including, in order from an object side to an image side, a first lens unit having negative optical power, a second lens unit having positive optical power, a third lens unit having negative optical power, and a fourth lens unit having positive optical power;

wherein each interval between the respective lens units is changed during zooming; and

wherein said diffractive optical element and said optical member are included in the fourth lens unit.

12. An optical system according to claim 1, wherein the optical system forms an image on a solid-state pick-up device.

13. An image pick-up apparatus comprising:

an optical system according to claim 1;

and

a solid-state pick-up device for receiving an image formed by the optical system.