Focal length changeable lens
AssigneeFuji Photo Optical Co., Ltd.
InventorHitoshi Miyano
Life of this patent
Estimating the term…
Abstract
A focal length changeable lens system for use with an on-chip micro-lens equipped solid-state imaging device, whose exit pupil is located at a long distance and whose focal length is changeable between a long focal length and a short focal length. The lens system includes a first positive power lens group, a second positive power lens group and a third positive power lens group arranged in order from the object end. The lens system further includes an aperture stop fixedly disposed between the first and second lens groups where the subject focal point of the third lens group is positioned. When the second lens group is out of the optical axis, the lens system provides a long focal length, and when the first lens group is out of the optical axis, the lens system provides a short focal length.
Claims6
A focal length changeable lens system with its exit pupil located at a long distance for use with an on-chip micro-lens equipped solid-state imaging device, whose focal length is changeable between a long focal length and a short focal length, said lens system comprising:
- a first lens group having a positive power, said first lens group being movable into an optical axis of the lens system for the long focal length and out of the optical axis for the short focal length;
- a second lens group having a positive power and disposed on the image end of the lens system relative to said first lens group, said second lens group being movable into the optical axis for the short focal length and out of the optical axis for the long focal length;
- an aperture stop fixedly disposed in the optical axis between said first lens group and said second lens group;
- and
- a third lens group having a positive power, said third lens group being fixedly disposed between said second lens group and the on-chip micro-lens equipped solid-state imaging device in the optical axis so as to place its object focal point near said aperture stop.
Dependencies are inferred from the claim text.