Endoscope objective lens

• US 6,400,514 B2
• Filed: 12/27/2000
• Issued: 06/04/2002
• Est. Priority Date: 01/12/2000
• Status: Expired due to Term

• Current Assignee: Fujinon Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Optical Co. Ltd (Fujifilm Holdings Corporation)
• Inventors: Miyano, Hitoshi, Minami, Itsuji
• Primary Examiner(s): Sugarman, Scott J.
• Application Number:
  US09/748,280
• Publication Number:
  US 20010007511A1
• Time in Patent Office: 524 Days
• Field of Search: 359/661, 359/680, 359/682
• US Class Current: 359/660
• CPC Class Codes: G02B 23/2438 Zoom objectives

Abstract

In an objective lens mounted to an endoscope having an enlarging function and enabling a switch to wide-field viewing, a movable lens group is moved so as to adjust the amount of curvature of field such that the image quality at marginal parts of a picture becomes favorable according to the form of an object while keeping a substantially constant magnification.

Claims

1. An endoscope objective lens comprising at least one movable lens group, said movable lens group being movable so as to improve field curvature correction wherein an image of a marginal part of a picture of an object is corrected while keeping magnification substantially constant.

2. An endoscope objective lens according to claim 1, wherein said endoscope objective lens is an optical system having a variable focus.

3. An endoscope objective lens according to claim 1, wherein said endoscope objective lens is an optical system having a fixed focus.

4. An endoscope objective lens according to claim 1, wherein said endoscope objective lens comprises, successively from the object side, a first lens group having a negative refracting power, a second lens group having a positive refracting power, and a third lens group having a positive refracting power;

said second and third lens group being movable along an optical axis so as to generate said field curvature correction.

5. An endoscope objective lens according to claim 4, further comprising a stop disposed near a lens constituting said second lens group on the object side.

6. An endoscope objective lens according to claim 1, wherein said endoscope objective lens comprises, successively from the object side, a first lens group having a negative refracting power, a second lens group having a positive refracting power, a third lens group having a negative refracting power, and a fourth lens group having a positive refracting power;

said second and third lens group being movable along an optical axis so as to generate said curvature correction.

7. An endoscope objective lens according to claim 6, further comprising a stop disposed between lenses in said third lens group.