# US 5,353,090 A · Camera

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- Number: US 5,353,090 A
- Document ID: US5353090A
- Status: Granted
- Kind: A
- Application number: 08/151,828
- Filed: 1993-11-15
- Granted: 1994-10-04
- Earliest claimed: 1992-11-17
- Assignees: Olympus Optical Co., Ltd.
- Inventors: Shigeru Kato
- Web page: https://patentgrep.com/patent/US5353090A

## CPC

- G02B 7/32: using active means, e.g. light emitter {(including both an active and a passive focus detecting device G02B7/285; using ultrasound G02B7/40)}
- G01S 17/46: Indirect determination of position data
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

A camera includes a finder optical system having an objective optical system and an eyepiece optical system, independent of a photographic optical system, and a range measuring optical system. A path splitting member Is disposed in the optical path of the objective optical system to make an optical axis of incident light introduced from the objective optical system into the eyepiece optical system coincide with an optical axis of the range measuring optical system, and satisfies conditions: 650 nm.ltoreq..lambda.(R.sub.0).ltoreq.850 nm R.sub.0 =[R(550 nm)+R(900 nm)]/2 where .lambda.(R.sub.0) is the wavelength at which the reflectance of the path splitting member regarding an axial ray changes to R.sub.0, and R(550 nm) and R(900 nm) are the reflectances of the path splitting member where the wavelengths of axial rays are 550 nm and 900 nm, respectively.

## Claims

### Claim 1

A camera comprising:
a finder optical system having an objective optical system and an eyepiece optical system, independent of a photographic optical system; and
a range measuring optical system,
wherein a path splitting member is disposed in an optical path of said objective optical system of said finder optical system to make an optical axis of incident light introduced from said objective optical system into said eyepiece optical system coincide with an optical axis of said range measuring optical system and satisfies conditions:
650 nm.ltoreq..lambda.(R.sub.0).ltoreq.850 nm
R.sub.0 =[R(550 nm)+R(900 nm)]/2
where .lambda.(R.sub.0) is a wavelength at which a reflectance of the path splitting member regarding an axial ray becomes R.sub.0, and R(550 nm) and R(900 nm) are reflectances of the path splitting member where wavelengths of axial rays are 550 nm and 900 nm, respectively.

### Claim 2 (depends on 1)

A camera according to claim 1, wherein said path splitting means is a wavelength selective mirror having a path splitting surface constructed of a multilayer thin film.

### Claim 3 (depends on 1)

A camera according to claim 1, wherein a lens having a positive refracting power is disposed in front said path splitting member.

### Claim 4 (depends on 1)

A camera according to claim 1, wherein a lens having a positive refracting power is disposed behind said path splitting member.