Immersion microscope objective and microscope using the same

1. An immersion microscope objective comprising, in order from an object side:

a first lens group having a positive refractive power;

a second lens group having a positive refractive power; and

a third lens group having a negative refractive power,

wherein:

the first lens group includes a cemented lens and at least one positive single lens, and the cemented lens includes a positive lens and a meniscus lens,

the second lens group changes a divergent light beam to a convergent light beam,

the third lens group includes an object-side lens group and an image-side lens group,

in the object-side lens group, a surface nearest to an image side is a concave surface which is directed toward the image side, and in the image-side lens group, a surface nearest to the object side is a concave surface which is directed toward the object side,

a plurality of lenses having a positive refractive power are provided,

at least one lens having a positive refractive power from among the plurality of lenses having a positive refractive power has a cemented surface which is cemented to a lens having a negative refractive power, and

the plurality of lenses having a positive refractive power include a lens which satisfies the following conditional expressions (1) and (2), and the following conditional expression (3) is satisfied:

−0.0065≦( n p1129 −n ps )/( n ps −1)≦−0.003  (1)

0.588≦1 /n ps ≦0.667  (2)

0.1 ≦d 1 /WD≦1  (3)

where,

n p1129 denotes a refractive index at a wavelength 1129 nm of the lens having a positive refractive power,

n ps denotes a refractive index for an s-line (wavelength 852.11 nm) of the lens having a positive refractive power,

WD denotes a working distance of the immersion microscope objective, and

d 1 denotes a thickness of the lens positioned nearest to the object side.

2. An immersion microscope objective comprising, in order from an object side:

a first lens group having a positive refractive power;

a second lens group having a positive refractive power; and

a third lens group having a negative refractive power,

wherein:

the first lens group includes a cemented lens and at least one positive single lens, and the cemented lens includes a positive lens and a meniscus lens,

the second lens group changes a divergent light beam to a convergent light beam,

the third lens group includes an object-side lens group and an image-side lens group,

in the object-side lens group, a surface nearest to an image side is a concave surface which is directed toward the image side, and in the image-side lens group, a surface nearest to the object side is a concave surface which is directed toward the object side,

a plurality of lenses having a positive refractive power are provided,

at least one lens having a positive refractive power from among the plurality of lenses having a positive refractive power has a cemented surface which is cemented to a lens having a negative refractive power, and

the following conditional expression (4) is satisfied:

0.8 ≦r 1c /r 1i ≦1.6  (4)

where,

r 1c denotes a radius of curvature of the cemented surface of the cemented lens in the first lens group, and

r 1i denotes a radius of curvature of the image-side surface of the cemented lens in the first lens group.

3. An immersion microscope objective comprising, in order from an object side:

a first lens group having a positive refractive power;

a second lens group having a positive refractive power; and

a third lens group having a negative refractive power,

wherein:

the first lens group includes a cemented lens and at least one positive single lens, and the cemented lens includes a positive lens and a meniscus lens,

the second lens group changes a divergent light beam to a convergent light beam,

the third lens group includes an object-side lens group and an image-side lens group,

in the object-side lens group, a surface nearest to an image side is a concave surface which is directed toward the image side, and in the image-side lens group, a surface nearest to the object side is a concave surface which is directed toward the object side,

a plurality of lenses having a positive refractive power are provided,

at least one lens having a positive refractive power from among the plurality of lenses having a positive refractive power has a cemented surface which is cemented to a lens having a negative refractive power, and

the following conditional expression (5) is satisfied:

−0.013≦( n n1129 −n ns )/( n ns −1)≦−0.0097  (5)

where,

n n1129 denotes a refractive index at a wavelength 1129 nm of the lens having a negative refractive power, and

n ns denotes a refractive index for an s-line (wavelength 852.11 nm) of the lens having a negative refractive power.

4. An immersion microscope objective comprising, in order from an object side:

a first lens group having a positive refractive power;

a second lens group having a positive refractive power; and

a third lens group having a negative refractive power,

wherein:

the first lens group includes a cemented lens and at least one positive single lens, and the cemented lens includes a positive lens and a meniscus lens,

the second lens group changes a divergent light beam to a convergent light beam,

the third lens group includes an object-side lens group and an image-side lens group,

in the object-side lens group, a surface nearest to an image side is a concave surface which is directed toward the image side, and in the image-side lens group, a surface nearest to the object side is a concave surface which is directed toward the object side,

a plurality of lenses having a positive refractive power are provided,

at least one lens having a positive refractive power from among the plurality of lenses having a positive refractive power has a cemented surface which is cemented to a lens having a negative refractive power, and

the following conditional expression (6) is satisfied:

0.29≦|(WD− d 1 )/ r 1c |≦0.48  (6)

where,

WD denotes a working distance of the immersion microscope objective,

d 1 denotes a thickness of the lens positioned nearest to the object side, and

r 1c denotes a radius of curvature of the cemented surface of the cemented lens in the first lens group.

5. An immersion microscope objective comprising, in order from an object side:

a first lens group having a positive refractive power;

a second lens group having a positive refractive power; and

a third lens group having a negative refractive power,

wherein:

the first lens group includes a cemented lens and at least one positive single lens, and the cemented lens includes a positive lens and a meniscus lens,

the second lens group changes a divergent light beam to a convergent light beam,

the third lens group includes an object-side lens group and an image-side lens group,

in the object-side lens group, a surface nearest to an image side is a concave surface which is directed toward the image side, and in the image-side lens group, a surface nearest to the object side is a concave surface which is directed toward the object side,

a plurality of lenses having a positive refractive power are provided,

at least one lens having a positive refractive power from among the plurality of lenses having a positive refractive power has a cemented surface which is cemented to a lens having a negative refractive power,

the second lens group includes a movable lens group which moves along an optical axis, and

the following conditional expressions (7) and (8) are satisfied:

−1.1≦ m g2 ≦−0.8  (7)

−0.3≦ f/f 2m ≦0  (8)

where,

m g2 denotes a magnification of the second lens group,

f denotes a focal length of the immersion microscope objective, and

f 2m denotes a focal length of the movable lens group.

6. A microscope comprising:

a scanner section;

a main-body section; and

the immersion microscope objective according to claim 1 .