A device for monitoring an area of coverage on a work tool may comprise a sensor, a camera, an evaluation unit, and at least one circuit output to activate the work tool only if no object is located in the area of coverage. The sensor may comprise a lighting unit to emit light rays to illuminate the area of coverage and a camera to detect three-dimensional images of the area of coverage, where the camera may include receiving elements in a matrix-type arrangement, the receiving elements to generate output signals. The evaluation unit is adapted to measure the output signals, to determine a distance value for each receiving element based on emitted light rays from the lighting unit traveling to the area of coverage and being reflected back.