Objective optical system
AssigneeOlympus Medical Systems Corp.
InventorHideyasu TAKATO
Life of this patent
Estimating the term…
Abstract
The invention relates to a high-performance imaging optical system that achieves a magnification high enough to be capable of microscopic viewing under an endoscope, and is compatible with high-definition imaging devices. The objective optical system comprises, at least in order from the object side, a positive, first group G1, a second group G2 and a third group G3. In association with an object point change, at least the second group G2 is moved along an optical axis. The objective optical system satisfies a condition with respect to an optical magnification β upon focusing on the closest range.
Claims5
An objective optical system, characterized by comprising, at least in order from an object side thereof, a positive, first group, a second group and a third group, wherein in association with an object point distance change, at least said second group is moved along an optical axis for focusing, with satisfaction of the following condition:
- |β|>1.8 (1)
- where β is an optical magnification upon focusing on the closest range.
An objective optical system, characterized by comprising, in order from an object side thereof, a positive, first group, a negative, second group and a positive, third group, wherein in association with an object point distance change, said second group is moved along an optical axis for focusing, with satisfaction of the following condition:
- |β|>1.8 (1)
- where β is an optical magnification upon focusing on the closest range.
An objective optical system, characterized by comprising, in order from an object side thereof, a positive, first group, a negative, second group and a positive, third group, wherein in association with an object point distance change, said second group is moved along an optical axis for focusing, with satisfaction of the following conditions (2) and (3):
- 0.7<f1/f<1.0 (2)
- 1.62<f2/f1<2.75 (3)
- where f is a focal length of the whole system (upon focusing on a far point),
- f1 is a focal length of the first group, and
- f2 is an absolute value of a focal length of the second group.
An objective optical system, characterized by comprising, in order from an object side thereof, a positive, first group, a negative, second group and a positive, third group, wherein in association with an object point distance change, said second group is moved together with a stop along an optical axis for focusing, with satisfaction of the following condition (4):
- 0.25<f1/f3<0.45 (4)
- where f1 is a focal length of the first group, and
- f3 is a focal length of the third group.
Dependencies are inferred from the claim text.