Patent ID: 7982961
Filing Date: 2011-07-19
Classification: G02B

Abstract:
1. A dry-type microscope objective lens comprising, in order from an object side, a first lens group, a second lens group, and a third lens group; wherein the first lens group comprises a meniscus lens which is arranged on the most object side and which turns its concave surface to the object side and the first lens group has positive refracting power as a whole, wherein the second lens group comprises plural cemented lens units and has positive refracting power as a whole, wherein the third lens group comprises air contact surfaces which are concave surfaces adjoining each other and facing toward each other and the third lens group has negative refracting power as a whole, and wherein the dry-type microscope objective lens satisfies the following conditions: where D is a distance from an object surface to the last surface of the objective lens, f is a focal length of the objective lens, NA is an object-side numerical aperture, f(Lm) is a focal length of the meniscus lens which is arranged on the most object side in the first lens group and which turns its concave surface to the object side, and Rm is an object-side radius of curvature of the meniscus lens.