A magnetic sensor comprises at least one first coil at an associated at least one first location of a body of a vehicle and operatively connected to a ferromagnetic element of the body. A monitor connected to the sensor monitors sensor use and stores indications of the use on sensor memory. The rinsing liquid supply nozzle is rotated to pass over the substrate and at the same time to discharge a rinsing liquid from its discharge unit. The measurement beam is focused on a reverse focal plane of the objective lens such that the measurement beam is collimated by the objective lens. The control element enables the first switching element to output an operating voltage.