Microscope objective lens

Abstract

A microscope objective lens is disclosed that includes, in order from the object side, a first lens group having positive refractive power, a second lens group having positive refractive power that is movable along the optical axis, and a third lens group. The first lens group includes, in order from the object side, two meniscus lens components, each with its concave surface on the object side, and at least one positive lens component, and the third lens group has adjacent concave lens element surfaces that face each other and are in contact with air. Specified conditions may be satisfied, and one or more lens components in the first lens group and the second lens group may be movable.

1 - 4 . (canceled) 
   
   
       5 . A microscope objective lens comprising, in order from the object side:
 a first lens group having positive refractive power that includes, in order from the object side, two meniscus lens components, each with its concave surface on the object side, and at least one positive lens component;   a second lens group having positive refractive power; and   a third lens group having adjacent concave lens element surfaces that face each other and are in contact with air;   
     wherein
 the second lens group satisfies the following condition:
   0.8≦|β2|≦1.2 
 
 
     where
 β2 is the lateral magnification of the second lens group when the object of the second lens group is the image formed by the first lens group. 
 
   
   
       6 . The microscope objective lens of  claim 5 , wherein the following additional conditions are satisfied:
   7≦f     0.5<NA   
     where
 f is the focal length (in mm) of the microscope objective lens, and 
 NA is the numerical aperture on the object side of the microscope objective lens. 
 
   
   
       7 - 11 . (canceled) 
   
   
       12 . A microscope objective lens comprising, in order from the object side:
 a first lens group having positive refractive power that includes, in order from the object side, a first meniscus lens component arranged nearest to the object side and with its concave surface on the object side and in contact with air, and a second meniscus lens component with its concave surface on the object side, and at least one positive lens component;   a second lens group having positive refractive power; and   a third lens group having adjacent concave lens element surfaces that face each other and are in contact with air;   wherein the following condition is satisfied:
   60<D≦120 
   
     where
 D is the on-axis distance (in mm) from an object under observation to a plane where said objective lens is mounted to the microscope body. 
 
   
   
       13 . The microscope objective lens of  claim 12 , wherein the following additional conditions are satisfied:
   7≦f     0.5<NA   
     where
 f is the focal length (in mm) of the microscope objective lens, and 
 NA is the numerical aperture on the object side of the microscope objective lens. 
 
   
   
       14 - 16 . (canceled)