# US 12,222,478 B2 · Optical system, optical apparatus and method for manufacturing the optical system

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- Number: US 12,222,478 B2
- Document ID: US12222478B2
- Status: Granted
- Kind: B2
- Application number: 17/636,862
- Filed: 2020-08-26
- Published: 2022-08-25
- Granted: 2025-02-11
- Earliest claimed: 2019-08-30
- Assignees: Nikon Corporation
- Applicants: Nikon Corporation
- Inventors: Masashi Yamashita; Tomoki Ito; Tomonori Kuribayashi; Keigo Koida; Satoshi Miwa; Yoko Komatsubara; Katsuya Watanabe; Azuna Nonaka; Ayumu Makida
- Web page: https://patentgrep.com/patent/US12222478B2

## CPC

- G02B 15/145121: {arranged +-+-+}
- G02B 9/64: having more than six components
- G02B 13/006: {at least one element being a compound optical element, e.g. cemented elements}
- G02B 15/145113: {arranged +-++-}
- G02B 15/145523: {arranged -++-+}
- G02B 15/1461: {the first group being positive}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An optical system (LS) has a lens (L11) that satisfies the following conditional expressions. −0.010<ndLZ−(2.015−0.0068×νdLZ) 50.00<νdLZ<65.00 0.545<θgFLZ −0.010<θgFLZ−(0.6418−0.00168×νdLZ) where ndLZ is the refractive index to the d line of the lens, νdLZ is the Abbe number with respect to the d line of the lens, and θgFLZ is the partial dispersion ratio of the lens.

## Claims

### Claim 1

An optical system comprising:
an aperture stop; and
a lens provided closer to an object than the aperture stop, the lens satisfying the following conditional expressions:
50.00<νdLZ<65.00,
0.545<θgFLZ≤0.5583,
−0.010<θgFLZ−(0.6418−0.00168×νdLZ)
where
νdLZ: a refractive index of the lens for d-line,
νdLZ: an Abbe number of the lens with reference to d-line, and
θgFLZ: a partial dispersion ratio of the lens, defined by a following expression when a refractive index of the lens for g-line is ngLZ, a refractive index of the lens for F-line is nFLZ, and a refractive index of the lens for C-line is nCLZ:
θgFLZ=(ngLZ−nFLZ)/(nFLZ−nCLZ).

### Claim 2 (depends on 1)

The optical system according to claim 1, consisting of:
the aperture stop; a front lens group disposed closer to an object than the aperture stop; and a rear lens group disposed closer to an image than the aperture stop,
wherein the front lens group includes the lens and satisfies the following conditional expression:
−10.00<fLZ|/fF<10.00
where fLZ: a focal length of the lens, and
fF: a focal length of the front lens group; in a case where the optical system is a zoom optical system, the focal length of the front lens group in the wide angle end state.

### Claim 3 (depends on 1)

The optical system according to claim 1,
wherein the lens satisfies the following conditional expression:
0.10<|fLZ|/f<15.00
where fLZ: a focal length of the lens, and
f: a focal length of the optical system; in a case where the optical system is a zoom optical system, the focal length of the optical system in a wide angle end state.

### Claim 4 (depends on 1)

The optical system according to claim 1,
wherein the lens satisfies the following conditional expression:
0.555<θgFLZ≤0.5583.

### Claim 5 (depends on 1)

The optical system according to claim 1,
wherein the lens satisfies the following conditional expression:
0.010<θgFLZ−(0.6418−0.00168×νdLZ).

### Claim 6 (depends on 1)

The optical system according to claim 1,
wherein the lens satisfies the following conditional expression:
DLZ>0.400 [mm]
where DLZ: a thickness of the lens on an optical axis.

### Claim 7 (depends on 1)

The optical system according to claim 1, wherein the lens is a single lens, or one lens of two lenses of a cemented lens consisting of the two lenses cemented to each other.

### Claim 8 (depends on 1)

The optical system according to claim 1, wherein at least one lens surface of an object-side lens surface and an image-side lens surface of the lens is in contact with air.

### Claim 9 (depends on 1)

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

### Claim 10 (depends on 1)

An optical apparatus comprising the optical system according to claim 1.

### Claim 11 (depends on 1)

The optical system according to claim 1, wherein the lens is a positive lens included in a lens group having positive refractive power, the lens group being provided closer to the object than the aperture stop.

### Claim 12 (depends on 1)

The optical system according to claim 1, wherein the lens is a negative lens included in a lens group having negative refractive power, the lens group being provided closer to the object than the aperture stop.

### Claim 13 (depends on 1)

The optical system according to claim 1, further comprising a first lens group having a positive refractive power provided closest to the object, a second lens group, and a third lens group, the first, second and third lens groups being provided closer to the object than the aperture stop, wherein the lens is one of a positive lens included in the first lens group, a negative lens included in the second lens group, or a positive lens included in the third lens group.

### Claim 14 (depends on 1)

The optical system according to claim 1, further comprising a first lens group having a negative refractive power, the first lens group being provided closest to the object, wherein the lens is a negative lens included in the first lens group.

### Claim 15

A method for manufacturing an optical system, the method comprising:
a step of arranging an aperture stop and at least one lens in a lens barrel so that the lens is provided closer to an object than the aperture stop, the lens satisfying the following conditional expressions:
50.00<νdLZ<65.00,
0.545<θgFLZ≤0.5583,
−0.010<θgFLZ−(0.6418−0.00168×νdLZ)
where
νdLZ: a refractive index of the lens for d-line,
νdLZ: an Abbe number of the lens with reference to d-line, and
θgFLZ: a partial dispersion ratio of the lens, defined by a following expression when a refractive index of the lens for g-line is ngLZ, a refractive index of the lens for F-line is nFLZ, and a refractive index of the lens for C-line is nCLZ:
θgFLZ=(ngLZ−nFLZ)/(nFLZ−nCLZ).