| 摘要 |
The invention provides an obstruction detection device. It comprises a light guide having at least one groove formed into one of the light-guiding surfaces of the light guide. A light emitter is provided for emitting light into the light guide, and at least one light detector is provided for detecting the intensity of light transmitted through the light guide and/or which is reflected by at least one groove inside the light guide. Further, the obstruction detection device comprises an output device for outputting an alarm signal when an absolute difference between the intensity and a reference value exceeds a threshold value.
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