Patent ID: 9341832
Filing Date: 2016-05-17
CPC Classification: G02B

Claim Text:
1. A microscope objective lens comprising, in order from an object side, a first lens group having positive refractive power, a second lens group having positive refractive power, and a third lens group having negative refractive power, wherein the first lens group includes, on the most object side, a positive meniscus lens whose concave surface is directed to the object side, the second lens group includes a diffractive optical element having positive refractive power, and the diffractive optical element is arranged at a position closer to the image than a portion at which the diameter of a light flux passing through the first lens group and the second lens group is the largest, the microscope objective lens satisfying the following expressions: where a refractive index relative to a d-line of a medium of the positive meniscus lens included in the first lens group is set as n1, a radius of curvature of the most object side lens surface of the first lens group is set as r1, a focal length of the whole lens system is set as F, the maximum diameter of the light flux passing through the first lens group and the second lens group is set as Φmax, and the maximum diameter of a light flux passing through a diffractive optical surface of the diffractive optical element is set as ΦDOE.