Objective for a confocal microscope
An objective includes: a first lens group that includes a meniscus lens component that is the closest to an image among lens components of the first lens group, the meniscus lens component having a convex surface facing an object; and a second lens group that is closer to the image than the first lens group is, and the objective satisfies the following conditional expressions: 0≤|Δ z 1 |/DOF e ≤1.5 (1) 0≤|Δ z 2 |/DOF e ≤2 (2) where Δz 1 indicates a difference between a h-line minimization position and an e-line minimization position; Δz 2 , a difference between a position on then optical axis at which an RMS wavefront aberration in light having a wavelength of 800 nm is minimized and the e-line minimization position; DOF e , a depth of focus for the e line.
1. An objective comprising:
a first lens group that includes a meniscus lens component that is closest to an image among lens components of the first lens group, the meniscus lens component having a convex surface facing an object; and
a second lens group that is closer to the image than the first lens group is, wherein
the objective satisfies the following conditional expressions:
0≤|Δ z 1 |/DOF e ≤1.5 (1)
0≤|Δ z 2 |/DOF e ≤2 (2)
where Δz 1 indicates a difference between a position on an optical axis at which an RMS wavefront aberration in an h line is minimized and a position on the optical axis at which an RMS wavefront aberration in an e line is minimized, Δz 2 indicates a difference between a position on the optical axis at which an RMS wavefront aberration in light having a wavelength of 800 nm is minimized and the position on the optical axis at which an RMS wavefront aberration in the e line is minimized, and DOF e indicates a depth of focus for the e line.
2. The objective of claim 1 , wherein
the first lens group includes a first lens component that is closest to the object among the lens components of the first lens group, the first lens component having a convex surface facing the image,
the objective satisfies the following conditional expression:
1.5≤ n 1 ≤1.85 (4)
where n 1 indicates a highest of refractive indexes that lenses included in the first lens component have for the e line.
3. The objective of claim 2 , wherein
the second lens group includes a plurality of lens components.
4. The objective of claim 2 , further comprising:
a cemented triplet lens, wherein
the objective satisfies the following conditional expression:
0.5≤NA ob (5)
where NA ob indicates a numerical aperture of an object side of the objective.
5. The objective of claim 1 , wherein
the second lens group includes a plurality of lens components.
6. The objective of claim 5 , further comprising:
a cemented triplet lens, wherein
the objective satisfies the following conditional expression:
0.5≤NA ob (5)
where NA ob indicates a numerical aperture of an object side of the objective.
7. The objective of claim 1 , further comprising:
a cemented triplet lens, wherein
the objective satisfies the following conditional expression:
0.5≤NA ob (5)
where NA ob indicates a numerical aperture of an object side of the objective.
8. The objective of claim 7 , wherein
the cemented triplet lens consists of a negative lens and two positive lenses having the negative lens situated therebetween.
9. The objective of claim 1 , wherein
the objective is an immersion objective, and
the objective satisfies the following conditional expressions:
1≤NA ob (6)
−0.2 ≤f ob /f 1 ≤0.43 (7)
where NA ob indicates a numerical aperture of an object side of the objective, f ob indicates a focal length that the objective has for the e line, and f 1 indicates a focal length that the first lens component has for the e line.
10. The objective of claim 1 , wherein
the objective is a dry objective,
the objective further comprises at least one lens component capable of being moved along the optical axis, and
the objective satisfies the following conditional expression:
0.85≤NA ob <1 (8)
where NA ob indicates a numerical aperture of an object side of the objective.
11. An objective comprising:
a first lens group that includes a meniscus lens component that is closest to an image among lens components of the first lens group, the meniscus lens component having a convex surface facing an object; and
a second lens group that is closer to the image than the first lens group is, wherein
the objective satisfies the following conditional expressions:
0 ≤|Δz 1 |/DOF e ≤1.5 (1)
9 mm≤ Y reso ×|β|≤20 mm (3)
where Δz 1 indicates a difference between a position on an optical axis at which an RMS wavefront aberration in an h line is minimized and a position on the optical axis at which an RMS wavefront aberration in an e line is minimized, DOF e indicates a depth of focus for the e line, Y reso indicates a maximum object height within a region on a plane orthogonal to the optical axial that crosses the position on the optical axis at which an RMS wavefront aberration in the e line is minimized, the region having an RMS wavefront aberration in the e line that is 0.2λ e or less provided therewithin, λ e indicates a wavelength of the e line, and β indicates a magnification of the objective.
12. The objective of claim 11 , wherein
the first lens group includes a first lens component that is closest to the object among the lens components of the first lens group, the first lens component having a convex surface facing the image,
the objective satisfies the following conditional expression:
1.5≤ n 1 ≤1.85 (4)
where n 1 indicates a highest of refractive indexes that lenses included in the first lens component have for the e line.
13. The objective of claim 12 , wherein
the second lens group includes a plurality of lens components.
14. The objective of claim 12 , further comprising:
a cemented triplet lens, wherein
the objective satisfies the following conditional expression:
0.5≤NA ob (5)
where NA ob indicates a numerical aperture of an object side of the objective.
15. The objective of claim 11 , wherein
the second lens group includes a plurality of lens components.
16. The objective of claim 15 , further comprising:
a cemented triplet lens, wherein
the objective satisfies the following conditional expression:
0.5≤NA ob (5)
where NA ob indicates a numerical aperture of an object side of the objective.
17. The objective of claim 11 , further comprising:
a cemented triplet lens, wherein
the objective satisfies the following conditional expression:
0.5≤NA ob (5)
where NA ob indicates a numerical aperture of an object side of the objective.
18. The objective of claim 17 , wherein
the cemented triplet lens consists of a negative lens and two positive lenses having the negative lens situated therebetween.
19. The objective of claim 11 , wherein
the objective is an immersion objective, and
the objective satisfies the following conditional expressions:
1≤NA ob (6)
−0.2≤ f ob /f 1 ≤0.43 (7)
where NA ob indicates a numerical aperture of an object side of the objective, f ob indicates a focal length that the objective has for the e line, and f 1 indicates a focal length that the first lens component has for the e line.
20. The objective of claim 11 , wherein
the objective is a dry objective,
the objective further comprises at least one lens component capable of being moved along the optical axis, and
the objective satisfies the following conditional expression:
0.85≤NA ob <1 (8)
where NA ob indicates a numerical aperture of an object side of the objective.