# US 8,785,837 B2 · Photoelectric barrier apparatus

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- Number: US 8,785,837 B2
- Document ID: US8785837B2
- Status: Granted
- Kind: B2
- Application number: 13/208,633
- Filed: 2011-08-12
- Published: 2012-03-01
- Granted: 2014-07-22
- Earliest claimed: 2010-08-31
- Assignees: Balluff GmbH
- Applicants: Stefan Hilsenbeck; Alexander Forkl
- Inventors: Stefan Hilsenbeck; Alexander Forkl
- Web page: https://patentgrep.com/patent/US8785837B2

## CPC

- G01V 3/14: operating with electron or nuclear magnetic resonance
- G01V: GEOPHYSICS; GRAVITATIONAL MEASUREMENTS; DETECTING MASSES OR OBJECTS; TAGS (means for indicating the location of accidentally buried, e.g. snow-buried, persons A63B29/02)

## Abstract

A photoelectric barrier apparatus is provided, which comprises a transmitting device for light, a reflecting device and a receiving device for reflected light with at least one photodetector, wherein the at least one photodetector is arranged at an acute angle to an optical axis, wherein the at least one photodetector has a receiving face for light and the acute angle lies between the optical axis and a normal of the receiving face.

## Claims

### Claim 1

Photoelectric barrier apparatus comprising:
a transmitting device for light;
a reflecting device; and
a receiving device for reflected light with at least one photodetector;
wherein:
the at least one photodetector is arranged at an acute angle to an optical axis;
the at least one photodetector has a receiving face for light and the acute angle lies between the optical axis and a normal of the receiving face;
the acute angle is the Brewster angle in relation to a medium, in which the at least one photodetector is arranged, and a light-transitive material of the at least one photodetector, or the acute angle lies close to the Brewster angle.

### Claim 2 (depends on 1)

Photoelectric barrier apparatus according to claim 1, wherein a deviation of the acute angle from the Brewster angle lies at most at 20°.

### Claim 3 (depends on 1)

Photoelectric barrier apparatus according to claim 1, wherein the acute angle lies in a range of between 50° and 85°.

### Claim 4 (depends on 3)

Photoelectric barrier apparatus according to claim 3, wherein the at least one photodetector is an Si photodetector arranged in an air environment.

### Claim 5 (depends on 1)

Photoelectric barrier apparatus according to claim 1, wherein the transmitting device and the receiving device are arranged in a common housing.

### Claim 6 (depends on 5)

Photoelectric barrier apparatus according to claim 5, wherein the reflecting device is arranged outside the housing.

### Claim 7 (depends on 1)

Photoelectric barrier apparatus according to claim 1, wherein said photoelectric barrier apparatus comprises a polariser device.

### Claim 8 (depends on 7)

Photoelectric barrier apparatus according to claim 7, wherein the polariser device comprises a first polarising filter, which is associated with the transmitting device.

### Claim 9 (depends on 8)

Photoelectric barrier apparatus according to claim 8, wherein the polariser device comprises a second polarising filter, which is associated with the receiving device.

### Claim 10 (depends on 9)

Photoelectric barrier apparatus according to claim 9, wherein the first polarising filter and the second polarising filter predetermine different linear polarisation directions.

### Claim 11 (depends on 8)

Photoelectric barrier apparatus according to claim 8, wherein the first polarising filter supplies transmission light, which is polarised perpendicularly to a plane of incidence.

### Claim 12 (depends on 1)

Photoelectric barrier apparatus according to claim 1, wherein no polariser device is provided.

### Claim 13 (depends on 12)

Photoelectric barrier apparatus according to claim 12, wherein the transmitting device is a laser light source.

### Claim 14 (depends on 1)

Photoelectric barrier apparatus according to claim 1, wherein the reflecting device is configured to rotate polarisation.

### Claim 15 (depends on 1)

Photoelectric barrier apparatus according to claim 1, wherein the at least one photodetector is subjected to light, which is polarised linearly in a plane of incidence, at least when the at least one photodetector is subjected to light reflected at the reflecting device and the reflecting device is configured to rotate polarisation.

### Claim 16 (depends on 1)

Photoelectric barrier apparatus according to claim 1, wherein an angular position of the at least one photodetector is adapted to be fixedly set at least during production of the photoelectric barrier device.