Patent ID: 7046451

Claim:
An immersion microscope objective lens comprising, in order from an object: a first lens group; a second lens group; and a third lens group, the first lens group including a first cemented lens constructed by a plano-convex lens having a plane surface facing to the object cemented with a meniscus lens having a convex surface facing to an image, and two or more cemented positive lenses disposed to the image side of the first cemented lens, the second lens group including one or more cemented lens, the third lens group including, in order from the object side, a cemented meniscus lens having a strong concave surface facing to the image, and a cemented meniscus lens having a strong concave surface facing to the object, and the following conditional expressions being satisfied: {| r 1 | 2 −(| r 1 |−d 1 ) 2 } 1/2 −[5.13×( d A −d B )+0.775]>0 | r 1 |+16.67×( n 1 −n 2 )/ n 1 /n 2 <0 0.10 <|f/f 3 |<0.16 where r 1 denotes a radius of curvature of a cemented surface between the plano-convex lens and the meniscus lens in the first lens group, d 1 denotes a thickness along the optical axis of the plano-convex lens, d A denotes a distance between the plane surface of the plano-convex lens and the object plane, d B denotes a thickness of a cover glass arranged between the plane surface and the object plane, n 1 denotes refractive index of the plano-convex lens, n 2 denotes refractive index of the meniscus lens, f denotes the focal length of the immersion microscope objective lens, and f 3 denotes the focal length of the third lens group.