Optical system, optical apparatus, and method of manufacturing optical system

Patent metadata

Field	Value
Publication number	US-12072476-B2
Application number	US-202318132463-A
Country	US
Kind code	B2
Filing date	Apr 10, 2023
Priority date	Dec 15, 2017
Publication date	Aug 27, 2024
Grant date	Aug 27, 2024

Abstract

An optical system (LS) includes lenses (L 22 ,L 23 ) satisfying the following conditional expressions,

ν d LZ<35.0, and

0.702<θ g FLZ+(0.00316×ν d LZ),
where νdLZ: Abbe number of the lens with reference to d-line, and
θgFLZ: a partial dispersion ratio of the lens, wherein θgFLZ is defined by the following expression,

θ g FLZ=( ng LZ− n FLZ)/( n FLZ− n CLZ).
wherein a refractive index of the lens with reference to g-line is ngLZ, a refractive index of the lens with reference to F-line is nFLZ, and a refractive index of the lens with reference to C-line is nCLZ.

First claim

The invention claimed is:

1. An optical system comprising a lens satisfying following conditional expressions:
20.00 <νd LZ<35.0
0.702 <θg FLZ+(0.00316×ν d LZ),

where
νdLZ: Abbe number of the specified lens with reference to d-line, and
θ g FLZ: a partial dispersion ratio of the lens,
wherein θ g FLZ is defined by the following expression,
θ g FLZ=( ng LZ− n FLZ)/( n FLZ− n CLZ)

wherein a refractive index of the lens with reference to g-line is ngLZ, a refractive index of the lens with reference to F-line is nFLZ, and a refractive index of the lens with reference to C-line is nCLZ.

2. The optical system according to claim 1 , wherein the lens satisfies the following conditional expression:
nd LZ+(0.01425×ν d LZ)<2.12

where
ndLZ: a refractive index of the lens with reference to d-line.

3. The optical system according to claim 1 , wherein the lens satisfies the following conditional expression:
1.83 <nd LZ+(0.00787×ν d LZ),

where
ndLZ: a refractive index of the lens with reference to d-line.

4. The optical system according to claim 1 , wherein the lens satisfies the following conditional expression:
1.55 <nd LZ

where
ndLZ: a refractive index of the lens with reference to d-line.

5. The optical system according to claim 1 , wherein the lens satisfies the following conditional expression:
DLZ>0.80

where
DLZ: a thickness [mm] of the lens on an optical axis.

6. The optical system according to claim 1 , wherein the lens satisfies the following conditional expressions:
nd LZ<1.63
nd LZ−(0.040×ν d LZ−2.470)×ν d LZ<39.809

where
ndLZ: a refractive index of the lens with reference to d-line.

7. The optical system according to claim 1 , wherein the lens satisfies the following conditional expression:
nd LZ−(0.020×ν d LZ−1.080)×ν d LZ<16.260

where
ndLZ: a refractive index of the lens with reference to d-line.

8. The optical system according to claim 1 , wherein the lens satisfies the following conditional expression:
20.00<ν d LZ<27.0.

9. The optical system according to claim 1 , wherein the lens satisfies the following conditional expression:
1.70 <nd LZ<1.85

where
ndLZ: a refractive index of the lens with reference to d-line.

10. The optical system according to claim 1 , wherein the lens satisfies the following conditional expression:
0.702 <θg FLZ+(0.00316×ν d LZ)<0.900.

11. The optical system according to claim 10 , wherein the lens satisfies the following conditional expression:
1.55 <nd LZ<1.70

where
ndLZ: a refractive index of the lens with reference to d-line.

12. The optical system according to claim 1 , wherein the lens satisfies the following conditional expression:
27.0<ν d LZ<35.0.

13. The optical system according to claim 12 , wherein the lens satisfies the following conditional expression:
1.55 <nd LZ<1.70

where
ndLZ: a refractive index of the lens with reference to d-line.

14. The optical system according to claim 1 , wherein the lens satisfies the following conditional expression:
25.0 <νd LZ<31.0.

15. The optical system according to claim 14 , wherein the lens satisfies the following conditional expression:
1.55 <nd LZ<1.80

where
ndLZ: a refractive index of the lens with reference to d-line.

16. The optical system according to claim 1 , comprising an object-side lens disposed nearest to an object,
wherein the lens is disposed nearer to an image than the object-side lens.

17. The optical system according to claim 1 , comprising an image-side lens disposed nearest to an image,
wherein the lens is disposed nearer to an object than the image-side lens.

18. The optical system according to claim 1 , wherein the lens is a glass lens.

19. An optical apparatus configured to comprise the optical system according to claim 1 .

20. The optical system according to claim 1 , wherein the lens is a single lens or a one of a cemented lens which is made by cementing two lenses.

21. The optical system according to claim 1 , wherein at least one of lens surfaces of the lens faces air.

22. A method of manufacturing an optical system, comprising:
disposing lenses within a lens barrel so as to include a lens satisfying the following conditional expressions:
20.00<ν d LZ<35.0

0.702 <θg FLZ+(0.00316 ×vd LZ),

where
vdLZ: Abbe number of the lens with reference to d-line, and
θgFLZ: a partial dispersion ratio of the lens,
wherein θgFLZ is defined by the following expression:
θ g FLZ=( ng LZ− n FLZ)/( n FLZ− n CLZ)

wherein a refractive index of the lens with reference to g-line is ngLZ, a refractive index of the lens with reference to F-line is nFLZ, and a refractive index of the lens with reference to C-line is nCLZ.

Assignees

• Nikon Corp

Inventors

• Yamashita Masashi
• Ito Tomoki
• Yabumoto Hiroshi
• Yamamoto Hiroshi
• Miwa Satoshi
• Tsubonoya Keisuke
• MAKIDA Ayumu
• Uehara Takeru

Classifications

• G02B27/0062

  by controlling the dispersion of a lens material, e.g. adapting the relative partial dispersion · CPC title

• G02B15/1461 Primary

  the first group being positive · CPC title

• G02B15/144511

  arranged -+-+ · CPC title

• G02B15/144113

  arranged +-++ · CPC title

• G02B15/143105

  arranged +-+ · CPC title