Patent ID: 11933961
Assignee: OLYMPUS CORPORATION
Field: Optics (Instruments)
Classification: CPC G  A | IPC A  G

Claim 8:
9. A stereoscopic vision endoscope objective optical system comprising, in order from an object side:
a first lens group having a negative refractive power;
a second lens group having a positive refractive power; and
a rear-side lens group having a positive refractive power,
wherein:
the rear-side lens group includes a first rear group and a second rear group,
the first lens group and the second lens group are disposed so that an optical axis of the second lens group coincides with an optical axis of the first lens group,
the optical axis of the first lens group is located between an optical axis of the first rear group and an optical axis of the second rear group,
each of the first rear group and the second rear group includes a first sub group, an aperture stop, and a second sub group,
the first sub group includes, in order from the object side, a negative lens and a positive lens,
the second sub group includes a front-side sub group having a negative refractive power and a rear-side sub group having a positive refractive power,
the rear-side sub group in the second sub group includes, in order from the object side, a positive lens, a positive lens, and a negative lens, and
the following conditional expressions (1) and (4′) are satisfied:

0<−f21n/fSUB≤3  (1)

0.5≤−f21n/f21p≤1  (4′)

where,
f21n denotes a focal length of the negative lens in the first sub group,
fSUB denotes a focal length of the first rear group or a focal length of the second rear group, and
f21p denotes a focal length of the positive lens in the first sub group.