Endoscope objective lens and endoscope
AssigneeFUJIFILM Corporation
InventorChikara Yamamoto
Life of this patent
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Abstract
The endoscope objective lens is configured such that focusing from the farthest object to the nearest object is achieved by moving at least one lens group other than the most object-side lens group along the optical axis. One of the at least one lens group to be moved during focusing is a negative lens group. The one negative lens group that is moved during the focusing consists of a cemented lens that is formed by a positive lens and a negative lens cemented together in this order from the object side. The cemented surface of the cemented lens is oriented such that the concave surface faces the object side. Given conditional expressions are satisfied.
Claims20
An endoscope objective lens configured such that focusing from a farthest object to a nearest object is achieved by moving at least one lens group other than a most object-side lens group along an optical axis,
- wherein one of the at least one lens group that is moved during the focusing is a negative lens group,
- the negative lens group consists of a cemented lens that is formed by a positive lens and a negative lens cemented together in this order from an object side, wherein a cemented surface of the cemented lens is oriented such that a concave surface faces the object side, and
- the conditional expressions (1) and (2) below are satisfied:
- 1.1≦ft/fw (1) and
- 0<νn−νp (2),
- where ft is a focal length of the entire system when the focus is set on the nearest object, fw is a focal length of the entire system when the focus is set on the farthest object, νn is an Abbe number with respect to the d-line of the negative lens forming the cemented lens, and νp is an Abbe number with respect to the d-line of the positive lens forming the cemented lens.
An endoscope objective lens configured such that focusing from a farthest object to a nearest object is achieved by moving at least one lens group other than a most object-side lens group along an optical axis,
- wherein one of the at least one lens group that is moved during the focusing is a negative lens group,
- the negative lens group consists of a cemented lens that is formed by a positive lens and a negative lens cemented together in this order from an object side, wherein a cemented surface of the cemented lens is oriented such that a concave surface faces the object side, and
- the conditional expressions (1) and (3) below are satisfied:
- 1.1≦ft/fw (1) and
- −20<1/(Pc×fw)<0 (3),
- where ft is a focal length of the entire system when the focus is set on the nearest object, fw is a focal length of the entire system when the focus is set on the farthest object, and Pc is a refractive power of the cemented surface of the cemented lens.
Dependencies are inferred from the claim text.