# US 10,871,641 B2 · Objective optical system for endoscope and endoscope

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 10,871,641 B2
- Document ID: US10871641B2
- Status: Granted
- Kind: B2
- Application number: 16/136,954
- Filed: 2018-09-20
- Published: 2019-03-28
- Granted: 2020-12-22
- Earliest claimed: 2017-09-27
- Assignees: FUJIFILM Corporation
- Applicants: FUJIFILM Corporation
- Inventors: Chikara Yamamoto
- Web page: https://patentgrep.com/patent/US10871641B2

## CPC

- G02B 23/243: {Objectives for endoscopes}
- A61B 1/00096: {Optical elements}
- A61B 1/00174: {characterised by the viewing angles}
- A61B 1/00188: {with focusing or zooming features}
- G02B 7/04: with mechanism for focusing or varying magnification
- G02B 13/04: Reversed telephoto objectives
- G02B 23/2461: {Illumination}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)

## Abstract

An objective optical system for an endoscope forms an intermediate image at a position conjugate to an object surface and forms the intermediate image on an imaging plane again, and is adapted to satisfy Conditional expressions (1) to (3) in a case in which a maximum effective image height on the imaging plane is denoted by HI, a focal length of the entire system is denoted by f, an effective luminous flux diameter on a lens surface closest to an object is denoted by FD, an F-Number of the entire system is denoted by FNo, and a paraxial relay magnification of the intermediate image on the imaging plane is denoted by R. 0.7<HI/|f| (1) FD×FNo/|f|6 (2) −2<βR<−0.8 (3).

## Claims

### Claim 1

An objective optical system for an endoscope comprising a plurality of lenses, that forms an intermediate image at a position conjugate to an object surface and forms the intermediate image on an imaging plane again,
wherein Conditional expressions (1) to (3) are satisfied in a case in which a maximum effective image height on the imaging plane is denoted by HI, a focal length of the objective optical system for an endoscope is denoted by f, an effective luminous flux diameter on a lens surface closest to an object of the objective optical system for an endoscope is denoted by FD, an F-Number of the objective optical system for an endoscope is denoted by FNo, and a paraxial relay magnification of the intermediate image on the imaging plane is denoted by βR,
0.7<HI/|f| (1)
FD×FNo/|f|<6 (2)
−2<βR<−0.8 (3).

### Claim 2 (depends on 1)

The objective optical system for an endoscope according to claim 1,
wherein Conditional expression (4) is satisfied in a case in which a maximum effective luminous flux diameter among effective luminous flux diameters on lens surfaces of the objective optical system for an endoscope is denoted by BD,
BD/(2×HI)<1.2 (4).

### Claim 3 (depends on 2)

The objective optical system for an endoscope according to claim 2,
wherein Conditional expression (4-1) is satisfied,
0.5<BD/(2×HI)<1.1 (4-1).

### Claim 4 (depends on 1)

The objective optical system for an endoscope according to claim 1,
wherein Conditional expression (5) is satisfied,
3<2×HI/FD (5).

### Claim 5 (depends on 4)

The objective optical system for an endoscope according to claim 4,
wherein Conditional expression (5-1) is satisfied,
3.5<2×HI/FD<30 (5-1).

### Claim 6 (depends on 1)

The objective optical system for an endoscope according to claim 1,
wherein Conditional expression (6) is satisfied in a case in which a half angle of view of the objective optical system for an endoscope is denoted by w,
HI/(tan(ω)×|f|)<0.75 (6).

### Claim 7 (depends on 6)

The objective optical system for an endoscope according to claim 6,
wherein Conditional expression (6-1) is satisfied,
0.01<HI/(tan(ω)×|f|)<0.65 (6-1).

### Claim 8 (depends on 1)

The objective optical system for an endoscope according to claim 1, further comprising:
a plane-parallel plate that is provided to be closer to the object than the lens surface closest to the object.

### Claim 9 (depends on 1)

The objective optical system for an endoscope according to claim 1,
wherein Conditional expression (1-1) is satisfied,
0.75<HI/|f|<10 (1-1).

### Claim 10 (depends on 1)

The objective optical system for an endoscope according to claim 1,
wherein Conditional expression (2-1) is satisfied,
0.9<FD×FNo/|f|<4.5 (2-1).

### Claim 11 (depends on 1)

The objective optical system for an endoscope according to claim 1,
wherein Conditional expression (3-1) is satisfied,
−1.5<βR<−0.9 (3-1).

### Claim 12 (depends on 1)

An endoscope comprising:
the objective optical system for an endoscope according to claim 1.