An apparatus and method determines the location of wafer boat plate elements having a plurality of plate elements arranged substantially parallel to each other. At least three sensors are moved along travel paths perpendicular to the plate elements, wherein at least a first travel path is above, at least a second travel path is below the wafer boat and at third travel path is laterally spaced from the first or second travel paths above or below the wafer boat. During this movement the position of the sensors along a respective travel path is determined continuously, and it is determined, in which position a respective plate element enters the measuring area of a sensor and exits the same. A distance between a sensor and an edge of a plate element is measured and the location of a respective plate element is determined by means of the sensor signals.
