Objective for microscope
An objective for a microscope includes, in order from an object side, a first lens group with positive refractive power, a second lens group with positive refractive power, and a third lens group with negative refractive power. When NA represents a numerical aperture of the objective, FN represents a field number of the objective, β represents a magnification of the objective, ε represents an Airy disk diameter on an axis to a d-line of the objective, φ max represents a maximum value of an effective diameter of a lens included in the objective, and h exp represents a radius of an exit pupil of the objective, the objective satisfies the following conditional expressions: 0.8≦NA≦1.5 (1) 1000≦FN/|β|/ε≦10000 (2) 1.7≦φ max /2/ h exp /NA≦4 (3).
1. An immersion type objective for a microscope, the immersion type objective comprising in order from an object side:
a first lens group with positive refractive power;
a second lens group with positive refractive power, the second lens group including a cemented lens that is configured of a lens with positive refractive power that is made of a low dispersion material and a lens with negative refractive power that is made of a high dispersion material; and
a third lens group with negative refractive power,
wherein:
the first lens group includes in order from the object side:
a first lens that is a single lens having a meniscus shape with a concave surface facing the object side, or a first cemented lens that is configured of the first lens and a lens arranged on the object side of the first lens;
a second lens that a single lens with positive refractive power, the single lens having a meniscus shape with a concave surface facing the object side; and
a third lens component that is a single lens or cemented lens with positive refractive power,
the third lens group includes a rear lens group with negative refractive power closest to an image side,
the rear lens group includes:
a fourth lens component that is a single lens or cemented lens having a meniscus shape with a concave surface facing the object side; and
a fifth lens component that is arranged closer to the object side than the fourth lens component and that is a single lens or cemented lens with negative refractive power with a concave surface facing the object side, and
when NA represents a numerical aperture of the objective, f represents a focal length of the objective, f G1 represents a focal length of the first lens group, r 12 represents a radius of curvature of a lens surface on the image side of the first lens, and d o12 represents a distance on an optical axis from a front-side focal plane of the objective to a lens surface on the image side of the first lens, the objective satisfies the following conditional expressions:
0.8≦NA≦1.5 (8)
2.3 ≦f G1 /f≦ 8 (9)
−1.5 ≦r 12 /d o12 ≦−0.75 (10).
2. The objective according to claim 1 , wherein the rear lens group further includes:
an eleventh lens component that is arranged closer to the object side than the fourth lens component and that is a single lens or cemented lens with negative refractive power.
3. The objective according to claim 1 , wherein:
the third lens group includes:
a front lens group arranged closest to the object side; and
an intermediate lens group arranged between the front lens group and the rear lens group, and
the intermediate lens group includes a twelfth lens component that is configured of a single lens or cemented lens having a meniscus shape with a convex surface facing the object side.
4. The objective according to claim 1 wherein the third lens component has a meniscus shape with a concave surface facing the object side.
5. The objective according to claim 1 , further comprising:
a sixth lens with positive refractive power that is made of a material having a high partial dispersion,
wherein, when D ogF represents a distance on the optical axis from the front-side focal plane of the objective to a lens surface on the image side of the sixth lens, and D oL represents a distance on the optical axis from the front-side focal plane of the objective to a lens surface closest to the image side in the objective, the objective satisfies the following conditional expression:
0.2 ≦D ogF /D oL ≦0.87 (11).
6. The objective according to claim 1 , wherein the first lens group includes a seventh lens component that is a single lens or cemented lens with positive refractive power, closer to the image side than the third lens component.
7. The objective according to claim 1 , wherein:
the third lens group includes a front lens group closest to the object side,
the front lens group includes:
an eighth lens with positive refractive power that is made of a low dispersion material; and
a ninth lens with negative refractive power that is made of a high dispersion material, the eighth lens and the ninth lens being arranged so as to be adjacent to each other,
a lens surface on a ninth-lens side of the eighth lens and a lens surface on an eighth lens-side of the ninth lens have a radius of curvature having the same sign, and
when f G3O represents a focal length of the front lens group, the objective satisfies the following conditional expression:
−0.3 ≦f/f G3O ≦0.3 (12).
8. A dry objective for a microscope, the dry objective comprising in order from an object side: a first lens croup with positive refractive power; a second lens group with positive refractive power, the second lens group including a cemented lens that is configured of a lens with positive refractive power that is made of a low dispersion material and a lens with negative refractive power that is made of a high dispersion material; and a third lens croup with negative refractive power, wherein: the first lens group includes in order from the object side: a first lens that is a single lens having a meniscus shape with a concave surface facing the object side; a second lens that is a single lens with positive refractive power, the single lens having a meniscus shape with a concave surface facing the object side; and a third lens component that is a single lens or cemented lens with positive refractive power, when NA represents a numerical aperture of the objective, f represents a focal length of the objective, f.sub.G 1 represents a focal length of the first lens group, r.sub. 11 represents a radius of curvature of a lens surface on the object side of the first lens, r.sub. 12 represents a radius of curvature of a lens surface on an image side of the first lens, and d.sub.o 12 represents a distance on an optical axis from a front-side focal plane of the objective to a lens surface on the image side of the first lens, the objective satisfies the following conditional expressions:
0.8.ltoreq.NA<1 (4)
1.6.ltoreq.f.sub.G1/f.ltoreq.6 (5)
−1.6.ltoreq.r.sub.11/f.ltoreq.−0.2 (6)
−2.ltoreq.r.sub.12/d.sub.o12.ltoreq.−0.86 (7)
the objective further comprises a sixth lens with positive refractive power that is made of a material having a high partial dispersion, and when D.sub.ogF represents a distance on the optical axis from the front-side focal plane of the objective to a lens surface on the image side of the sixth lens, and D.sub.oL represents a distance on the optical axis from the front-side focal plane of the objective to a lens surface closest to the image side in the objective, the objective satisfies the following conditional expression:
0.2.ltoreq.D.sub.ogF/D.sub.oL.ltoreq.0.87 (11).
9. A dry objective for a microscope, the dry objective comprising in order from an object side:
a first lens group with positive refractive power;
a second lens group with positive refractive power, the second lens group including a cemented lens that is configured of a lens with positive refractive power that is made of a low dispersion material and a lens with negative refractive power that is made of a high dispersion material; and
a third lens group with negative refractive power,
wherein:
the first lens group includes in order from the object side:
a first lens that is a single lens having a meniscus shape with a concave surface facing the object side;
a second lens that is a single lens with positive refractive power, the single lens having a meniscus shape with a concave surface facing the object side; and
a third lens component that is a single lens or cemented lens with positive refractive power, and
when NA represents a numerical aperture of the objective, f represents a focal length of the objective, f G1 represents a focal length of the first lens group, r 11 represents a radius of curvature of a lens surface on the object side of the first lens, r 12 represents a radius of curvature of a lens surface on an image side of the first lens, d o12 represents a distance on an optical axis from a front-side focal plane of the objective to a lens surface on the image side of the first lens, and f L2 represents a focal length of the second lens, the objective satisfies the following conditional expressions:
0.8≦NA<1 (4)
1.6 ≦f G1 /f≦ 6 (5)
−1.6≦ r 11 /f≦ −0.2 (6)
−2 ≦r 12 /d o12 ≦−0.86 (7)
0.05≦ f G1 /f L2 ≦0.6 (13).
10. A dry objective for a microscope, the dry objective comprising in order from an object side:
a first lens group with positive refractive power;
a second lens group with positive refractive power, the second lens group including a cemented lens that is configured of a lens with positive refractive power that is made of a low dispersion material and a lens with negative refractive power that is made of a high dispersion material; and
a third lens group with negative refractive power,
wherein:
the first lens group includes in order from the object side:
a first lens that is a single lens having a meniscus shape with a concave surface facing the object side;
a second lens that is a single lens with positive refractive power, the single lens having a meniscus shape with a concave surface facing the object side; and
a third lens component that is a single lens or cemented lens with positive refractive power, and
when NA represents a numerical aperture of the objective, f represents a focal length of the objective, f G1 represents a focal length of the first lens group, r 11 represents a radius of curvature of a lens surface on the object side of the first lens, r 12 represents a radius of curvature of a lens surface on an image side of the first lens, d o12 represents a distance on an optical axis from a front-side focal plane of the objective to a lens surface on the image side of the first lens, and f L3 represents a focal length of the third lens component, the objective satisfies the following conditional expressions:
0.8≦NA<1 (4)
1.6≦ f G1 /f≦ 6 (5)
−1.6≦ r 11 /f≦− 0.2 (6)
−2≦ r 12 /d o12 ≦−0.86 (7)
0.03≦ f G1 /f L3 ≦0.5 (14).
11. An objective for a microscope, the objective comprising in order from an object side:
a first lens group with positive refractive power;
a second lens group with positive refractive power; and
a third lens group with negative refractive power,
wherein, when NA represents a numerical aperture of the objective, FN represents a field number of the objective, β represents a magnification of the objective, ε represents an Airy disk diameter on an axis to a d-line of the objective, φ max represents a maximum value of an effective diameter of a lens included in the objective, and h exp represents a radius of an exit pupil of the objective, the objective satisfies the following conditional expressions:
0.8≦NA≦1.5 (1)
1000≦FN/|β|/ε≦10000 (2)
1.7≦φ max /2/ h exp /NA≦4 (3).