# US 5,703,718 A · Object reflector detecting apparatus

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- Number: US 5,703,718 A
- Document ID: US5703718A
- Status: Granted
- Kind: A
- Application number: 08/265,145
- Filed: 1994-06-24
- Granted: 1997-12-30
- Earliest claimed: 1993-06-25
- Assignees: Topcon Corporation
- Inventors: Fumio Ohtomo; Kunihiro Hayashi; Jun-ichi Kodaira; Hiroyuki Nishizawa; Kenichiro Yoshino
- Web page: https://patentgrep.com/patent/US5703718A

## CPC

- G01S 7/499: using polarisation effects
- G01C 15/002: {Active optical surveying means (optical plumbing G01C15/105)}
- G01S 7/491: Details of non-pulse systems
- G01S 17/04: Systems determining the presence of a target
- G02B 27/28: for polarising (used in stereoscopes G02B30/25)
- 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
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

An object reflector detecting apparatus for identifying an object reflector by emitting a light from a polarized light source toward the object reflector and then detecting a reflected light from the object reflector characterized in that the light emitted from said polarized light source is a polarized light of which direction of polarization is specially defined, the polarized lights between said reflected light and said emitted light are different in the direction of polarization, and said object reflector detecting apparatus is adapted to detect only a component of the direction of polarization from said object reflector.

## Claims

### Claim 1

Apparatus for detecting polarized light comprising;
a polarized light source for emitting polarized light;
circular polarizing means for circularly polarizing the polarized light emitted from said polarized light source;
rotary means for irradiating said circularly polarized light on a reference plane;
an objective reflector positioned to reflect light emitted by said polarized light source, said object reflector comprising at least one retro-reflective member and a quarter-wave birefringent member disposed in front of said at least one retro-reflective member, and said at least one retro-reflective member and said birefringent member being configured so that light impinging on said object reflector and light reflected from said object reflector have different directions of polarization;
detector means for detecting only the polarized light reflected from said object reflector; and
control means for moving the emitted polarized light in a reference plane on said object reflector.

### Claim 2 (depends on 1)

The apparatus of claim 1, wherein said polarized light source is stationary, and wherein said circular polarizing means is interposed between said polarized light source and said rotary means.

### Claim 3 (depends on 2)

The apparatus of claim 2, wherein said circular polarizing means comprises a birefringent member.

### Claim 4 (depends on 1)

The apparatus of claim 1, wherein said birefingent member has an optic axis inclined at an angle of about 45.degree. with respect to a scanning direction of the polarized light emitted by said polarized light source.

### Claim 5 (depends on 1)

The apparatus of claim 1, wherein said object reflector includes at least first and second spaced retro-reflective zones.

### Claim 6

Apparatus for detecting polarized light comprising;
a polarized light source for emitting polarized light;
circular polarizing means for circularly polarizing the polarized light emitted from said polarized light source;
rotary means for irradiating said circularly polarized light on a reference plane;
an object reflector positioned to reflect light emitted by said polarized light source, said object reflector comprising at least one retro-reflective member and a quarter-wave birefingent member disposed in front of said at least one retro-reflective member, and said at least one retro-reflective member and said birefringent member being configured so that light impinging on said object reflector and light reflected from said object reflector have different directions of polarization;
detector means for detecting only the polarized light reflected from said object reflector; and
control means for rotationally scanning the polarized light from said polarized light source on said object reflector.

### Claim 7 (depends on 6)

The apparatus of claim 6, wherein said object reflector includes at least first and second spaced retro-reflective zones.

### Claim 8

Apparatus for detecting polarized light comprising:
a polarized light source for emitting polarized light;
circular polarizing means for circularly polarizing the polarized light emitted from said polarized light source;
rotary means for irradiating said circularly polarized light on a reference plane;
an object reflector positioned to reflect light emitted by said polarized light source, said object reflector comprising at least one retro-reflective member and a quarter-wave birefringent member disposed in front of said at least one retro-reflective member, and said at least one retro-reflective member and said birefringent member being configured so that light impinging on said object reflector and light reflected from said object reflector have different directions of polarization;
detector means for detecting only the polarized light reflected from said object reflector; and
control means for reciprocally scanning the polarized light from said polarized light source on said object reflector.

### Claim 9 (depends on 8)

The apparatus of claim 8, wherein said object reflector includes at least first and second spaced retro-reflective zones.