Laser scanner

• US 20140111805A1
• Filed: 10/17/2013
• Published: 04/24/2014
• Est. Priority Date: 10/19/2012
• Status: Active Grant

• Current Assignee: Sick AG (Sick)
• Original Assignee: Sick AG (Sick)
• Inventors: ALBERT, Magnus, ENGLER, Michael, KRAMER, Joachim
• Granted Patent: US 9,477,007 B2
• Time in Patent Office: Days
• US Class Current: 356/369
• CPC Class Codes: G01S 17/93 for anti-collision purposes
• CPC Class Codes: G01S 7/499 using polarisation effects
• CPC Class Codes: G01V 8/10 Detecting, e.g. by using light barriers by reflection from the object G01S17/00

Abstract

A laser scanner, in particular a safety laser scanner, in accordance with the operating principle of the time of flight process, comprising a light transmission unit having at least one light transmitter for transmitting a polarized transmitted light beam into a monitored zone; a light reception unit having at least one light receiver for detecting the polarization component of the light reflected in the monitored zone being orthogonal to the polarization direction of the transmitted light beam, and/or the polarization component of the light reflected in the monitored zone being parallel to the polarization direction of the transmitted light beam, and for generating a received signal corresponding to the detected orthogonal polarization component and/or the detected parallel polarization component; and an evaluation unit configured to evaluate the time development of the detected orthogonal polarization component and/or of the detected parallel polarization component.

Claims

1. A laser scanner (10) in accordance with the operating principle of the time of flight process for detecting objects (19) in a monitored zone (18), comprising

a light transmission unit having at least one light transmitter (12) for transmitting a polarized transmitted light beam (14) into the monitored zone (19);

a light reception unit (24, 48) having at least one light receiver (24) for detecting the polarization component of the light (20) reflected in the monitored zone (19) which is orthogonal to the polarization direction of the transmitted light beam (14) and/or for detecting the polarization component of the light (20) reflected in the monitored zone (19) which is parallel to the polarization direction of the transmitted light beam (14) and for generating a received signal (38) corresponding to the detected orthogonal polarization component and/or for generating a received signal (40) corresponding to the detected parallel polarization component; and

an evaluation unit (32) which is configured to evaluate the time curve of the received signal (38) of the detected orthogonal polarization component and/or to evaluate the time curve of the received signal (40) of the detected parallel polarization component.

2. The laser scanner in accordance with claim 1 configured as a safety laser scanner.

3. The laser scanner in accordance with claim 1, wherein the light reception unit (24, 48) comprises a polarization filter which is arranged in front of the at least one light receiver (24) in the propagation direction of the reflected light (20) and which is aligned orthogonal to the polarization direction of the transmitted light beam (14).

4. The laser scanner in accordance with claim 1, wherein the evaluation unit (32) is configured to recognize different maxima (42, 44, 46) and/or different flank gradients in at least one of the two curves (38, 40).

5. The laser scanner in accordance with claim 1, wherein the evaluation unit (32) is configured to evaluate the two curves (38, 40) together.

6. The laser scanner in accordance with claim 5, wherein the evaluation unit (32) is configured to compare the two curves (38, 40) with one another.

7. The laser scanner in accordance with claim 1, wherein the evaluation unit (32) is configured to recognize interference signals (46) caused by external phenomena (50) in at least one of the two curves (38, 40) and/or to recognize a visibility impairment.

8. The laser scanner in accordance with claim 1, wherein the evaluation unit (32) is configured to determine at least one of the following members of the group comprising a value for a light damping, a light absorption and a visual range in dependence on the evaluation of at least one of the two curves (38, 40).

9. The laser scanner in accordance with claim 1, wherein the evaluation unit (32) is configured to set the luminous intensity of the transmitted light beam (14) in dependence on the evaluation of at least one of the two curves (38, 40).

10. The laser scanner in accordance with claim 1, wherein the light reception unit (24, 48) comprises a polarization beam splitter (48) which is arranged in front of the at least one light receiver (24) in the propagation direction of the reflected light (20) and which splits the reflected light (20) into the orthogonal polarization component and the parallel polarization component.

11. The laser scanner in accordance with claim 1, wherein the light transmission unit comprises two light transmitters which are each configured to transmit a polarized transmitted light beam into the monitored zone (18).

12. The laser scanner in accordance with claim 11, wherein the polarization directions of the two transmitted light beams are aligned orthogonal to one another.

13. The laser scanner in accordance with claim 11, wherein the wavelength and/or the frequency spectrum of the two transmitted light beams is identical.

14. The laser scanner in accordance with claim 1, wherein the at least one light receiver (24) is configured as a spatially resolving light receiver, has two reception regions spatially separate from one another and/or has two separate light receivers to detect the orthogonal polarization component of the reflected light (20) and the parallel polarization component of the reflected light (20) independently of one another.

15. A method for detecting objects in a monitored region, wherein

a polarized transmitted light beam is transmitted into the monitored zone;

the polarization component of the light reflected from the monitored zone which is orthogonal to the polarization direction of the transmitted light beam and/or the polarization component of the light reflected in the monitored zone which is parallel to the polarization direction of the transmitted light beam and a received signal corresponding to the detected orthogonal polarization component is generated and/or a received signal corresponding to the detected parallel polarization component is generated; and

the time curve of the received signal of the detected orthogonal polarization component is detected and/or the time curve of the received signal of the detected polarization component is evaluated.