Objective lens system for microscopes

Claim 1

An objective lens system for a microscope comprising, in order from an object side: a first lens component; and a second lens component; each of said first lens component and said second lens component being a radial type graded refractive index lens component having a refractive index distribution N(r) satisfying the following condition: N(r)=N.sub.00 +N.sub.10 r.sup.2 +N.sub.20 r.sup.4 + said reference symbol r representing a distance as measured from an optical axis in a radial direction, said reference symbol N 00 representing a refractive index of said lens component as measured on said optical axis thereof, and said reference symbols N 10 , N 20 , . . . denoting refractive index distribution coefficients of second, fourth, . . . orders respectively; said first lens component being disposed on the most object side in said lens system; said first lens component and said second lens component each satisfying the following condition (1), and said first lens component further satisfying the following conditions (2) and (7): φ.sub.1 /φ.sub.2 >1 (1) N.sub.10 <0 (2) -0.05<1/V.sub.10 <1/V.sub.00 ( 7) said reference symbols φ 1 and φ 2 represent refractive powers of said first lens component and said second lens component, respectively, and said reference symbols V 00 and V 10 represent Abbe's numbers which are determined by the following formulas: V.sub.00 =(N.sub.00d -1)/(N.sub.00F -N.sub.00C) V.sub.10 =N.sub.10d /(N.sub.10F -N.sub.10C) wherein said reference symbols N 00d , N 00F and N 00C represent refractive indices for the d-line, F-line and C-line, respectively, as measured on said optical axis, and said reference symbols N 10d , N 10F and N 10C represent the second order refractive index distribution coefficients for the d-line, F-line and C-line, respectively.