Zoom lens and optical apparatus using the same

• US 6,577,450 B2
• Filed: 09/25/2001
• Issued: 06/10/2003
• Est. Priority Date: 09/29/2000
• Status: Expired due to Fees

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Saruwatari, Hiroshi, Hamano, Hiroyuki
• Primary Examiner(s): Sugarman, Scott J.
• Assistant Examiner(s): RAIZEN, DEBORAH A
• Application Number:
  US09/961,302
• Publication Number:
  US 20020063969A1
• Time in Patent Office: 623 Days
• Field of Search: 359/687, 359/686, 359/742
• US Class Current: 359/687
• CPC Class Codes: G02B 15/144113 arranged +-++
• 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
• CPC Class Codes: G02B 27/4288 having uniform diffraction efficiency over a large spectral bandwidth

Abstract

A zoom lens which has good optical performance with the number of lenses reduced as a result of forming a diffraction optical surface is disclosed. The zoom lens includes, in order from object side to image side, a first lens unit consisting of a positive lens element and having a positive optical power, a second lens unit having a negative optical power, a third lens unit having a positive optical power, and a fourth lens unit having a positive optical power. When zooming is performed from a wide angle end to a telephoto end, the first lens unit and the third lens unit are moved so that, at the telephoto end, they are closer to the object side, and the second lens unit is moved so that, at the telephoto end, it is closer to the image side. The zoom lens further includes at least one diffraction optical surface.

Claims

1. A zoom lens comprising in order from object side to image side:

a first lens unit having a positive optical power, the first lens unit consisting of a positive lens element;

a second lens unit having a negative optical power;

a third lens unit having a positive optical power; and

a fourth lens unit having a positive optical power,

wherein, when zooming is carried out from a wide angle end to a telephoto end, the first lens unit and the third lens unit are moved so that, at the telephoto end, the first lens unit and the third lens unit are positioned closer to the object side than at the wide angle end, and the second lens unit is moved so that, at the telephoto end, the second lens unit is positioned closer to the image side than at the wide angle end, and

wherein the zoom lens further comprises at least one diffraction optical surface.

2. A zoom lens according to claim 1, wherein the following condition is satisfied:

3. A zoom lens according to claim 1, wherein the following condition is satisfied:

4. A zoom lens according to claim 1, wherein the following condition is satisfied:

5. A zoom lens according to claim 1, wherein the second lens unit consists of a negative lens element and a positive lens element.

6. A zoom lens according to claim 5, wherein the following condition is satisfied:

7. A zoom lens according to claim 1, wherein the second lens unit includes a diffraction optical surface.

8. A zoom lens according to claim 7, wherein the following condition is satisfied:

9. A zoom lens according to claim 1, wherein the first lens unit includes a diffraction optical surface.

10. A zoom lens according to claim 1, wherein the third lens unit includes a diffraction optical surface.

11. A zoom lens according to claim 1, wherein the diffraction optical surface has a layered structure of at least two layers.

12. A zoom lens according to claim 1, wherein, when focusing is performed, the fourth lens unit moves.

13. A zoom lens according to claim 1, wherein the zoom lens is an optical system for forming an image on an image pickup device.

14. An optical apparatus comprising the zoom lens of claim 1.

15. An optical apparatus according to claim 14 further comprising an image pickup device that is disposed at an image formation surface of the zoom lens.