Patent ID: 11931004
Assignee: OLYMPUS CORPORATION
Field: Optics (Instruments)
Classification: CPC A  G | IPC A  G

Claim 1:
2. The objective optical system according to claim 1, wherein the first spherical lens and the second spherical lens have radii identical to each other and are made of materials identical to each other; a surface on the object side of the first optical medium is a flat surface perpendicular to the optical axis; and the following conditional expression (1) is satisfied:

0≤{n1(2n3−n1)−n1LN}/{2n3−(n1−3n3)(n1−2)−(n1−1)LN}≤2  (1)

where
n1 indicates a refractive index of the first spherical lens and the second spherical lens,
R1 indicates a radius of the first spherical lens and the second spherical lens,
n3 indicates a refractive index of the first optical medium,
L indicates the interval on the optical axis between a surface on the opposite side of the first spherical lens from the object and the surface on the object side of the second spherical lens, and
N=(n1n3+n1−2n3)/R1.