| US 7,589,311 B2 | ||
| Optoelectronic sensor and method for detecting objects with polarized light | ||
| Ingolf Hoersch, Emmendingen (Germany); Felix Lang, Schliengen (Germany); and Rolf Meier, Ettenheim (Germany) | ||
| Assigned to Sick AG, Waldkirch (Germany) | ||
| Filed on Nov. 09, 2007, as Appl. No. 11/983,649. | ||
| Claims priority of application No. 10 2006 053 229 (DE), filed on Nov. 11, 2006. | ||
| Prior Publication US 2009/0108185 A1, Apr. 30, 2009 | ||
| Int. Cl. G01J 4/00 (2006.01) | ||
| U.S. Cl. 250—221 [250/216] | 15 Claims |
| 1. An optoelectronic sensor for detecting objects comprising
at least one light source, at least one light receiver, and a light retroreflector between them arranged for transmitting
light from the source to the detector along a light transmission path from the source to the retroreflector and back to the
detector along a light reflection path that substantially corresponds to the transmission path,
one of a single lens and a pair of adjacent lenses for shaping respective light beams from both light emitted by the source
and light reflected by the retroreflector in accordance with one of the auto collimation principle and the double-eye principle,
respectively,
a polarizer and a beam splitter in the light transmission path for light from the source,
a polarization filter in the light reflection path arranged so that light reflected by the retroreflector passes through the
beam splitter and the polarization filter, and
a control unit configured to recognize an interruption of at least one of the light beams as a detection of an object,
the beam splitter comprising a dielectricum which has differing transmission and reflection characteristics for p-polarized
light and s-polarized light.
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