Microscope objective

Claim 2

A microscope objective lens system comprising a plurality of lens elements or components which are arranged along a common optical axis, at least one of said lens elements or components being a graded refractive index lens, whose refractive index varies with the radial distance from said optical axis, and said graded refractive index lens being located on the object side of a point of intersection of an off-axial principal ray and said optical axis, wherein the refractive index distribution of said graded refractive index lens is expressed by the formula shown below, and said graded refractive index lens satisfies condition (1) shown below: n=n.sub.0 +n.sub.1 r.sup.2 +n.sub.2 r.sup.4 +n.sub.3 r.sup.6 + . . . |n.sub.1 |>7×10.sup.-4 /f.sup.2 ( 1) n 0 represents the refractive index on the optical axis, r represents the radial distance from the optical axis, n 1 , n 2 , n 3 , . . . respectively represent the 2nd-, 4th-, 6th-, . . . order coefficients, and f represents the focal length of said objective lens system.

Claim 3

A microscope objective lens system according to claim 1, wherein a lens element located on the most object side is a meniscus lens having a concave surface facing the object side, and said lens element is a graded refractive index lens, whose refractive index varies with the radial distance from said optical axis.

Claim 4

A microscope objective lens system according to claim 2, wherein a first positive lens located on the image side of said meniscus lens; a second positive lens spaced apart from said first positive lens at a substantial distance; and a meniscius lens component, which has a concave surface facing the image side; are arranged in that order from the object side, said first positive lens being a graded refractive index lens, whose refractive index varies with the radial distance from said optical axis.

Claim 5

A microscope objective lens system according to claim 1, said graded refractive index lens further satisfying the condition (3) shown below: |n.sub.1 |>|n.sub.i |, i≧3 (3) where n i =n i /f 2i .

Claim 6

A microscope objective lens system according to claim 1, wherein a lens element located on the most object side is a plano-convex lens having a plane surface on the object side, and said plano-convex lens is a graded refractive index lens whose refractive index varies with the radial distance from said optical axis.

Claim 7

A microscope objective lens system according to claim 5, wherein said plurality of lens elements or components include first and second positive lens components located on the image side of said plano-convex lens element, and third lens component having a concave surface facing the image side, said first and second positive lens components being spaced apart from said third lens component at a substantial distance, at least one of said first and second positive lens components being a graded refractive index lens, whose refractive index varies with the radial distance from said optical axis.

Claim 8

A microscope objective lens system according to claim 5, wherein said plurality of lens elements or components include a pair of lens components, the facing surfaces of which are both concave, on the image side of said plano-convex lens element, said pair of lens components including at least one graded refractive index lens, whose refractive index varies with the radial distance from said optical axis.

Claim 9

A microscope objective lens system according to claim 5, having the following data: ______________________________________ r.sub.1 = ∞ d.sub.1 = 0.8889 n.sub.01 = 1.63980* r.sub.2 = -7.4105 d.sub.2 = 0.0131 r.sub.3 = 1713.8486 d.sub.3 = 0.2502 n.sub.02 = 1.49700 r.sub.4 = -1.7788 d.sub.4 = 0.5388 n.sub.03 =1.79952* r.sub.5 = -1.3234 d.sub.5 = 0.0131 r.sub.6 = 24.5284 d.sub.6 = 0.4578 n.sub.04 = 1.67000* r.sub.7 = -3.7949 d.sub.7 = 1.9044 r.sub.8 = 2.6069 d.sub.8 = 0.6026 n.sub.05 = 1.65830* r.sub.9 = ∞ d.sub.9 = 0.6903 n.sub.06 = 1.61293* r.sub.10 = 0.6670 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 1st lens 0.56264 -0.51213 the 3rd lens -0.11046 0.37325 × 10.sup.-1 the 4th lens -0.12854 -0.73600 × 10.sup.-1 the 5th lens -0.25773 -0.72271 × 10.sup.-1 the 6th lens 0.16576 × 10.sup.-2 -0.12224 ______________________________________ f = 1 m = 20 WD = 0.2427 NA = 0.46 where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 10

A microscope objective lens system according to claims 1, 2 or 3, wherein a lens element on the most object side is a meniscus lens having a concave surface facing the object side, which has a uniform refractive index.

Claim 11

A microscope objective lens system according to claim 9, having the following data: ______________________________________ r.sub.1 = -0.6144 d.sub.1 = 1.0054 n.sub.01 = 1.78590* r.sub.2 = -0.9063 d.sub.2 = 0.0129 r.sub.3 = -11.8711 d.sub.3 = 0.5453 n.sub.02 = 1.76180* r.sub.4 = -1.9559 d.sub.4 = 2.5506 r.sub.5 = 14.2613 d.sub.5 = 0.2171 n.sub.03 = 1.49700 r.sub.6 = -2.8644 d.sub.6 = 0.0129 r.sub.7 = 2.5836 d.sub.7 = 0.6761 n.sub.04 = 1.65830 r.sub.8 = ∞ d.sub.8 = 0.3728 n.sub.05 = 1.61340 r.sub.9 = 1.1081 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 1st lens 0.16838 0.60574 × 10.sup.-1 the 2nd lens -0.13761 -0.54513 × 10.sup.-2 ______________________________________ f = 1 m = 20 WD = 0.2456 NA = 0.46 where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 12

A microscope objective lens system according to claim 9, having the following data: ______________________________________ r.sub.1 = -0.7070 d.sub.1 = 1.0402 n.sub.01 = 1.78590* r.sub.2 = -0.9457 d.sub.2 = 0.0130 r.sub.3 = -7.5963 d.sub.3 = 0.5582 n.sub.02 = 1.76180* r.sub.4 = -1.7635 d.sub.4 = 2.2760 r.sub.5 = 7.1126 d.sub.5 = 0.4596 n.sub.03 = 1.49700 r.sub.6 = -2.7181 d.sub.6 = 0.0130 r.sub.7 = 2.7615 d.sub.7 = 1.1005 n.sub.04 = 1.65830 r.sub.8 = 1.0582 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 1st lens 0.28629 0.10903 the 2nd lens -0.18390 -0.78497 × 10.sup.-2 ______________________________________ f = 1 m = 20 WD = 0.2486 NA = 0.46 where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 13

A microscope objective lens system according to claim 9, having the following data: ______________________________________ r.sub.1 = -0.4538 d.sub.1 = 0.6875 n.sub.01 = 1.83400 r.sub.2 = -0.7384 d.sub.2 = 0.0128 r.sub.3 = -2.2225 d.sub.3 = 0.2726 n.sub.02 = 1.49700 r.sub.4 = -1.1462 d.sub.4 = 0.0128 r.sub.5 = -50.2670 d.sub.5 = 0.6930 n.sub.03 = 1.76180 r.sub.6 = -3.5196 d.sub.6 = 2.4305 r.sub.7 = 3.5395 d.sub.7 = 0.3499 n.sub.04 = 1.49700 r.sub.8 = -4.1378 d.sub.8 = 0.0128 r.sub.9 = 1.9530 d.sub.9 = 0.8743 n.sub.05 = 1.65830* r.sub.10 = 0.9857 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 5th lens -0.14689 × 10.sup.-2 -0.60052 × 10.sup.-3 ______________________________________ f = 1 m = 20 WD = 0.2434 NA = 0.46 where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 14

A microscope objective lens system according to claim 9, having the following data: ______________________________________ r.sub.1 = -0.4496 d.sub.1 = 0.6812 n.sub.01 = 1.83400 r.sub.2 = -0.7511 d.sub.2 = 0.0127 r.sub.3 = -2.6794 d.sub.3 = 0.2542 n.sub.02 = 1.49700 r.sub.4 = -1.0686 d.sub.4 = 0.0127 r.sub.5 = -39.6904 d.sub.5 = 0.6420 n.sub.03 = 1.76180 r.sub.6 = -4.0568 d.sub.6 = 2.4876 r.sub.7 = 4.1051 d.sub.7 = 0.3941 n.sub.04 = 1.60178* r.sub.8 = -4.6364 d.sub.8 = 0.0127 r.sub.9 = 1.9945 d.sub.9 = 0.8333 n.sub.05 = 1.66083* r.sub.10 = 0.9754 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 4th lens -0.36453 × 10.sup.-1 0.98488 × 10.sup.-2 the 5th lens 0.13955 × 10.sup. -1 -0.25987 × 10.sup.-1 ______________________________________ f = 1 m = 20 WD = 0.2427 NA = 0.46 where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 15

A microscope objective lens system according to claim 9, having the following data: ______________________________________ r.sub.1 = -0.6202 d.sub.1 = 1.0101 n.sub.01 = 1.78590* r.sub.2 = -0.9334 d.sub.2 = 0.0129 r.sub.3 = -25.9860 d.sub.3 = 0.5460 n.sub.02 = 1.76180* r.sub.4 = -1.8355 d.sub.4 = 2.5837 r.sub.5 = 17.0878 d.sub.5 = 0.2177 n.sub.03 = 1.49700 r.sub.6 = -2.8475 d.sub.6 = 0.0129 r.sub.7 = 2.3126 d.sub.7 = 1.0278 n.sub.04 = 1.65830* r.sub.8 = 1.3126 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 1st lens 0.20954 0.55868 × 10.sup.-1 the 2nd lens -0.12844 0.81108 × 10.sup.-2 the 4th lens 0.18233 × 10.sup.-2 0.56092 × 10.sup.-3 ______________________________________ f = 1 m = 20 WD = 0.2464 NA = 0.46 where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 16

A microscope objective lens system according to claim 9, having the following data: ______________________________________ r.sub.1 = -0.6082 d.sub.1 = 0.9974 n.sub.01 = 1.77250* r.sub.2 = -0.9962 d.sub.2 = 0.0127 r.sub.3 = 4.5931 d.sub.3 = 0.5346 n.sub.02 = 1.77250* r.sub.4 = -2.1599 d.sub.4 = 2.6874 r.sub.5 = 5.1919 d.sub.5 = 1.0629 n.sub.03 = 1.83400* r.sub.6 = 1.5327 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 1st lens 0.15622 0.27687 × 10.sup.-1 the 2nd lens -0.93618 × 10.sup.-1 0.19220 × 10.sup.-1 the 3rd lens -0.16188 0.32660 × 10.sup.-1 ______________________________________ f = 1 m = 20 WD = 0.2417 NA = 0.46 where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 17

A microscope objective lens system according to claim 9, having the following data: ______________________________________ r.sub.1 = -0.5249 d.sub.1 = 0.9910 n.sub.01 = 1.77250 r.sub.2 = -1.0014 d.sub.2 = 0.0124 r.sub.3 = 4.7627 d.sub.3 = 0.5335 n.sub.02 = 1.77250* r.sub.4 = -2.2014 d.sub.4 = 2.6257 r.sub.5 = -23.3838 d.sub.5 = 1.0309 n.sub.03 = 1.83400* r.sub.6 = 3.3579 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 2nd lens -0.55298 × 10.sup.-1 -0.63272 × 10.sup.-2 the 3rd lens -0.13406 0.43943 × 10.sup.-1 ______________________________________ f = 1 WD = 0.2371 m = 20 × NA = 0.46 ______________________________________ where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 18

A microscope objective lens system according to claim 9, having the following data: ______________________________________ r.sub.1 = -0.8938 d.sub.1 = 1.3014 n.sub.01 = 1.60311* r.sub.2 = -1.0761 d.sub.2 = 0.0485 r.sub.3 = -12.5422 d.sub.3 = 1.2779 n.sub.02 = 1.49700* r.sub.4 = -2.1073 d.sub.4 = 0.1196 r.sub.5 = -5.9203 d.sub.5 = 4.0147 n.sub.03 = 1.65830* r.sub.6 = -15.8260 d.sub.6 = 2.4285 r.sub.7 = 50.5226 d.sub.7 = 1.2080 n.sub.04 = 1.69680 r.sub.8 = -45.6551 d.sub.8 = 0.8486 r.sub.9 = 8.8504 d.sub.9 = 3.9661 n.sub.05 = 1.64769* r.sub.10 = 8.1084 d.sub.10 = 0.0901 r.sub.11 = 5.3751 d.sub.11 = 3.3167 n.sub.06 = 1.69680* r.sub.12 = 1.8122 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 1st lens -0.55383 × 10.sup.-1 0.75335 × 10.sup.-2 the 2nd lens 0.36158 × 10.sup.-2 -0.67351 × 10.sup.-2 the 3rd lens -0.48852 × 10.sup.-2 0.55867 × 10.sup.-3 the 5th lens -0.91403 × 10.sup.-2 0.61851 × 10.sup.-4 the 6th lens 0.29971 × 10.sup.-2 -0.79363 × 10.sup.-3 ______________________________________ f = 1 WD = 0.2747 m = 100 × NA = 0.93 ______________________________________ where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 19

A microscope objective lens system according to claim 9, having the following data: ______________________________________ r.sub.1 = -0.9046 d.sub.1 = 1.3174 n.sub.01 = 1.60311* r.sub.2 = -1.0892 d.sub.2 = 0.0490 r.sub.3 = -14.5015 d.sub.3 = 1.2957 n.sub.02 = 1.49700* r.sub.4 = -2.1711 d.sub.4 = 0.1210 r.sub.5 = -9.4617 d.sub.5 = 4.1552 n.sub.03 = 1.65830* r.sub.6 = -74.3330 d.sub.6 = 2.6622 r.sub.7 = 14.4729 d.sub.7 = 1.2227 n.sub.04 = 1.69680 r.sub.8 = 76.2347 d.sub.8 = 1.4766 r.sub.9 = 7.4458 d.sub.9 = 4.4476 n.sub.05 = 1.64769* r.sub.10 = 5.3166 d.sub.10 = 0.0912 r.sub.11 = 4.1294 d.sub.11 = 3.4526 n.sub.06 = 1.69680 r.sub.12 = 1.8342 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 1st lens -0.44747 × 10.sup.-1 0.62120 × 10.sup.-2 the 2nd lens 0.46213 × 10.sup.-2 -0.63046 × 10.sup.-2 the 3rd lens -0.37359 × 10.sup.-2 0.78555 × 10.sup.-3 the 5th lens -0.52911 × 10.sup.-2 -0.54567 × 10.sup.-4 ______________________________________ f = 1 WD = 0.2780 m = 100 × NA = 0.93 ______________________________________ where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 20

A microscope objective lens system according to claim 9, having the following data: ______________________________________ r.sub.1 = -0.9096 d.sub.1 = 1.3245 n.sub.01 = 1.60075* r.sub.2 = -1.0952 d.sub.2 = 0.0493 r.sub.3 = -14.1908 d.sub.3 = 1.3024 n.sub.02 = 1.49816* r.sub.4 = -2.1963 d.sub.4 = 0.1217 r.sub.5 = -10.1842 d.sub.5 = 4.1444 n.sub.03 = 1.80715* r.sub.6 = -39.8009 d.sub.6 = 6.9678 r.sub.7 = 6.1099 d.sub.7 = 4.0578 n.sub.04 = 1.69783* r.sub.8 = 8.5336 d.sub.8 = 3.4046 n.sub.05 = 1.72825 r.sub.9 = 2.0713 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 1st lens -0.45357 × 10.sup.-1 0.60265 × 10.sup.-2 the 2nd lens 0.45552 × 10.sup.-2 -0.58051 × 10.sup.-2 the 3rd lens -0.78030 × 10.sup.-2 0.68623 × 10.sup.-3 the 4th lens -0.69381 × 10.sup.-2 -0.72030 × 10.sup.-4 ______________________________________ f = 1 WD = 0.2795 m = 100 × NA = 0.93 ______________________________________ where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 21

A microscope objective lens system according to claim 9, having the following data: ______________________________________ r.sub.1 = -0.9102 d.sub.1 = 1.3253 n.sub.01 = 1.60023* r.sub.2 = -1.0959 d.sub.2 = 0.0493 r.sub.3 = -14.9113 d.sub.3 = 1.3034 n.sub.02 = 1.49944* r.sub.4 = -2.2018 d.sub.4 = 0.1218 r.sub.5 = -9.1663 d.sub.5 = 4.2035 n.sub.03 = 1.85239* r.sub.6 = -30.0889 d.sub.6 = 6.8824 r.sub.7 = 5.4337 d.sub.7 = 4.0753 n.sub.04 = 1.53018* r.sub.8 = 5.8757 d.sub.8 = 3.4069 n.sub.05 = 1.72825 r.sub.9 = 1.9552 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 1st lens -0.43188 × 10.sup.-1 0.56817 × 10.sup.-2 the 2nd lens 0.49284 × 10.sup.-2 -0.58945 × 10.sup.-2 the 3rd lens -0.82238 × 10.sup. -2 0.69973 × 10.sup.-3 the 4th lens -0.69388 × 10.sup.-2 -0.79032 × 10.sup.-4 ______________________________________ f = 1 WD = 0.2797 m = 100 × NA = 0.93 ______________________________________ where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 22

A microscope objective lens system according to claim 9, having the following data: ______________________________________ r.sub.1 = -1.0065 d.sub.1 = 1.2888 n.sub.01 = 1.70154 r.sub.2 = -1.1460 d.sub.2 = 0.0480 r.sub.3 = 42.7198 d.sub.3 = 1.2684 n.sub.02 = 1.49944* r.sub.4 = -2.2385 d.sub.4 = 0.1186 r.sub.5 = -7.2241 d.sub.5 = 4.1668 n.sub.03 = 1.85239* r.sub.6 = -21.1737 d.sub.6 = 3.4460 r.sub.7 = 4.2290 d.sub.7 = 3.9676 n.sub.04 = 1.53018* r.sub.8 = -11.4298 d.sub.8 = 3.3015 n.sub.05 = 1.57309 r.sub.9 = 1.6647 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 2nd lens -0.24757 × 10.sup.-2 -0.52109 × 10.sup.-2 the 3rd lens -0.51876 × 10.sup.-2 0.11213 × 10.sup.-2 the 4th lens -0.78173 × 10.sup.-2 -0.25718 × 10.sup.-3 ______________________________________ f = 1 WD = 0.2724 m = 100 × NA = 0.93 ______________________________________ where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.

Claim 23

A microscope objective lens system according to claim 9, including a first positive lens component, second positive lens component, and a third lens component having a concave surface facing the image side, in that order, at the rear of said meniscus lens, said first positive lens component being spaced apart from said second positive lens component at a substantial distance, and each of said meniscus lens and said first positive lens component being a graded refractive index lens, whose refractive index varies with the radial distance from the optical axis.

Claim 24

A microscope objective lens system according to claim 22, wherein said third lens component, which has a concave surface facing the image side, is a graded refractive index lens, whose refractive index varies with the radial distance from the optical axis.

Claim 25

A microscope objective lens system according to claim 9, including a first positive lens component and second lens component having a concave surface facing the image side, in that order, at the rear of said meniscus lens, said first positive lens component being spaced apart from said second lens component at a substantial distance and both said first positive lens component and said second lens component being a graded refractive index lens, whose refractive index vary with the radial distance from the optical axis.

Claim 26

A microscope objective lens system according to claim 24, wherein said meniscus lens is a graded refractive index lens, whose refractive index varies with the radial distance from the optical axis.

Claim 27

A microscope objective lens system according to claim 9, including first and second lens components and third lens component having a concave surface facing the image side, in that order, at the rear of said meniscus lens, said second lens component being spaced apart from said third lens component at a substantial distance at least one of these lens components being a graded refractive index lens, whose refractive index varies with the radial distance form the optical axis.

Claim 28

A microscope objective lens system according to claim 26, wherein said meniscus lens is a graded refractive index lens, whose refractive index varies with the radial distance from the optical axis.

Claim 29

A microscope objective lens system according to claim 27, wherein said third lens component is a cemented doublet.

Claim 30

A microscope objective lens system according to claim 27, wherein said third lens component consists of two lens elements separated from each other.

Claim 31

A microscope objective lens system according to claim 27, wherein a fourth lens component is arranged between said second lens component and said third lens component.

Claim 32

A microscope objective lens system according to claim 30 wherein said third lens component is a cemented doublet.

Claim 33

A microscope objective lens system according to claim 30 wherein said third lens component consists of two lens elements separated from each other.

Claim 34

A microscope objective lens system comprising a plurality of lens elements or components which are arranged along a common optical axis, at least one of said lens elements or components being a graded refractive index lens, whose refractive index varies with the radial distance from the optical axis, and said graded refractive index lens being located on the image side of a point of intersection of an off-axial principal ray and said optical axis, wherein the refractive index distribution of said graded refractive index lens is expressed by the formula shown below and said graded refractive index lens satisfies the condition (2) shown below. n=n.sub.0 +n.sub.1 r.sup.2 +n.sub.2 r.sup.4 +n.sub.3 r.sup.6 + . . . |n.sub.1 |>7×10.sup.-4 /f.sup.2 ( 2) where n 0 represents the refractive index on the optical axis, r represents the radial distance from the optical axis, n 1 , n 2 , n 3 , . . . respectively represent the 2nd-, 4th-, 6th-, . . . order coefficients, and f represents the focal length of said objective lens system.

Claim 35

A microscope objective lens system comprising a plurality of lens elements or components which are arranged along a common optical axis, at least one of said lens elements or components being a graded refractive index lens, whose refractive index varies with the radial distance from the optical axis, and said graded refractive index lens being located on the image side of a point of intersection of an off-axial principal ray and said optical axis, wherein the refractive index distribution of said graded refractive index lens is expressed by the formula shown below and said graded refractive index lens satisfies the condition (2) shown below. n=n.sub.0 +n.sub.1 r.sup.2 +n.sub.2 r.sup.4 +n.sub.3 r.sup.6 + . . . |n.sub.1 |>7×10.sup.-4 /f.sup.2 ( 2) where n 0 represents the refractive index on the optical axis, r represents the radial distance from the optical axis, n 1 , n 2 , n 3 , . . . respectively represent the 2nd-, 4th-, 6th-, . . . order coefficients, and f represents the focal length of said objective lens system.

Claim 36

A microscope objective lens system according to claim 33, wherein a lens component located on the most image side has a concave surface facing the image side, and said lens component comprises at least one graded refractive index lens, whose refractive index varies with the radial distance from said optical axis.

Claim 37

A microscope objective lens system according to claim 34, wherein a meniscus lens component having a concave surface facing the object side, and first, second and third, positive lenses are located in that order on the object side, said second positive lens being spaced apart from said third positive lens at a distance.

Claim 38

A microscope objective lens system according to claim 35 wherein said third positive lens is a graded refractive index lens, whose refractive index varies with the radial distance from said optical axis.

Claim 39

A microscope objective lens system according to claim 33, said graded refractive index lens further satisfying the condition (3) shown below: |n.sub.1 |>|n.sub.i |, i≧3 (3) where n i =n i /f 2i .

Claim 40

A microscope objective lens system comprising a plurality of lens elements or components which are arranged along a common optical axis, at least two of said lens elements or components being graded refractive index lenses whose refractive index vary with the radial distance from the optical axis, at least one of said graded refractive index lenses being located on the object side of a point of intersection of an off-axial principal ray and said optical axis, and the remaining graded refractive index lenses being located on the image side of said point, wherein the refractive index distribution of said graded refractive index lenses is expressed by the formula shown below, said graded refractive index lens on the object side of said point satisfies the condition (1) shown below, and said graded refractive index lens on the image side of said point satisfies the condition (2) shown below: n=n.sub.0 +n.sub.1 r.sup.2 +n.sub.2 r.sup.4 +n.sub.3 r.sup.6 + . . . |n.sub.1 |>7×10.sup.-4 /f.sup.2 ( 1) |n.sub.1 |>1×10.sup.-4 /f.sup.2 ( 2) n 0 represents the refractive index on the optical axis, r represents the radical distance from the optical axis, n 1 , n 2 , n 3 , . . . respectively represent the 2nd-, 4th-, 6th-, . . . order coefficients, and f represents the focal length of said objective lens system.

Claim 41

A microscope objective lens system comprising a plurality of lens elements or components which are arranged along a common optical axis, at least two of said lens elements or components being graded refractive index lenses whose refractive index vary with the radial distance from the optical axis, at least one of said graded refractive index lenses being located on the object side of a point of intersection of an off-axial principal ray and said optical axis, and the remaining graded refractive index lenses being located on the image side of said point, wherein the refractive index distribution of said graded refractive index lenses is expressed by the formula shown below, said graded refractive index lens on the object side of said point satisfies the condition (1) shown below, and said graded refractive index lens on the image side of said point satisfies the condition (2) shown below: n=n.sub.0 +n.sub.1 r.sup.2 +n.sub.2 r.sup.4 +n.sub.3 r.sup.6 + . . . |n.sub.1 |>7×10.sup.-4 /f.sup.2 ( 1) |n.sub.1 |>1×10.sup.-4 /f.sup.2 ( 2) n 0 represents the refractive index on the optical axis, r represents the radical distance from the optical axis, n 1 , n 2 , n 3 , . . . respectively represent the 2nd-, 4th-, 6th-, . . . order coefficients, and f represents the focal length of said objective lens system.

Claim 42

A microscope objective lens system according to claim 38, wherein said plurality of lens elements or components include a foremost meniscus lens element located on the most object side, said meniscus lens element having a concave surface facing the object side, and a rearmost lens component located on the most image side, said lens component having a concave surface facing the image side, and said meniscus lens element being a graded refractive index lens, whose refractive index varies with the radial distance from said optical axis.

Claim 43

A microscope objective lens system according to claim 39, further including a positive lens, and a thick lens having a concave surface facing the object side said rearmost lens components consisting of two lens elements, said thick lens and either of said two lens elements of said rearmost lens component being graded refractive index lenses, whose refractive indices vary with the radial distances from the optical axis.

Claim 44

A microscope objective lens system according to claim 40, wherein another lens component is located between said thick lens and said rearmost lens component.

Claim 45

A microscope objective lens system according to claim 41, wherein both of said two lens elements of said rearmost lens component are graded refractive index lenses, whose refractive indices vary with the radial distances from the optical axis.

Claim 46

A microscope objective lens system according to claim 38, wherein said plurality of lens elements or components include a meniscus lens element located on the most object side, said meniscus lens element having a concave surface facing the object side, and a rearmost lens component located on the most image side, said rearmost lens component having a concave surface facing the image side, and said rearmost lens component including at least one graded refractive index lens, whose refractive index varies with the radial distance from said optical axis.

Claim 47

A microscope objective lens system according to claim 43, wherein a first positive lens element is located on the image side of said meniscus lens element, said positive lens element being a graded refractive index lens, whose refractive index varies with the radial distance from the optical axis.

Claim 48

A microscope objective lens system according to claim 44, wherein a second lens element is located on the image side of said first positive lens element, and has a concave surface facing the object side, said second lens element being a graded refractive index lens, whose refractive index varies with the radial distance from the optical axis.

Claim 49

A microscope objective lens system according to claim 38, wherein said plurality of lens elements or components include a meniscus lens element located on the most object side, said meniscus lens element having a concave surface facing the object side, and a rearmost lens component located on the most image side, said rearmost lens component having a concave surface facing the image side, said meniscus lens element being a graded refractive index lens, and said rearmost lens component including at least one graded refractive index lenses, the refractive index of each of said graded refractive index lenses varying with the radial distances from said optical axis.

Claim 50

A microscope objective lens system according to claim 46, wherein a first positive lens is located on the image side of said meniscus lens element, said first positive lens being a graded refractive index lens, whose refractive index varies with the radial distance from said optical axis.

Claim 51

A microscope objective lens system according to claim 47, wherein a second positive lens is located on the object side of said rearmost lens component.

Claim 52

A microscope objective lens system according to claim 38, said graded refractive index lens further satisfying the condition (3) shown below: |n.sub.1 |>|n.sub.i |, i≧3 (3) where n i =n i /f 2i .

Claim 53

A microscope objective lens system according to claim 38, having the following data: ______________________________________ r.sub.1 = ∞ d.sub.1 = 0.5027 n.sub.01 = 1.83400* r.sub.2 = -0.7363 d.sub.2 = 0.0125 r.sub.3 = 0.5038 d.sub.3 = 0.2311 n.sub.02 = 1.49700 r.sub.4 = ∞ d.sub.4 = 0.1868 n.sub.03 = 1.74000* r.sub.5 = 0.3873 d.sub.5 = 0.2353 r.sub.6 = -0.3567 d.sub.6 = 0.1005 n.sub.04 = 1.67270* r.sub.7 = ∞ d.sub.7 = 0.4094 n.sub.05 = 1.49700* r.sub.8 = -0.7164 d.sub.8 = 0.0184 r.sub.9 = 4.7830 d.sub.9 = 0.3580 n.sub.06 = 1.66755* r.sub.10 = -1.2326 d.sub.10 = 1.5374 r.sub.11 = 1.0611 d.sub.11 = 0.6214 n.sub.07 = 1.54869 r.sub. 12 = 0.7628 ______________________________________ n.sub.1 n.sub.2 ______________________________________ the 1st lens -0.24460 -0.25363 the 3rd lens 0.36245 × 10.sup.-1 0.48691 the 4th lens 0.92425 × 10.sup.-1 0.63217 the 5th lens 0.10171 0.75023 × 10.sup.-1 the 6th lens -0.58875 × 10.sup.-1 -0.22649 × 10.sup.-2 ______________________________________ f = 1 WD = 0.4513 m = 20 × NA = 0.46 ______________________________________ where r 1 , r 2 , . . . respectively represent the radii of curvature of respective lens surfaces, d 1 , d 2 , . . . respectively represent the thickness of respective lenses and the air-spaces between respective lenses, n 01 , n 02 , . . . respectively represent the refractive indices of respective lenses (or the refractive indices on the optical axis in the case of said graded refractive index lenses to which an asterisk * is attached), WD represents the working distance, m represents the magnification, and NA represents the numerical aperture.