Device and method for sensing wafer-shaped objects and shelves in a container

摘要

A device and method for the sensing of wafer-shaped objects and shelves in a container is disclosed. The device and method function to increase the reliability of detection in containers which are open on one side as well as in containers which are open on two sides, and to detect whether a shelf is occupied by more than one object, to detect oblique positions of the objects along several shelves and the position of the shelves themselves independent from dimensional tolerances without impeding the handling of either the wafer-shaped objects or the container and without interfering with clean room conditions. Radiation from a radiation source which is reflected at the front sides of the objects and at the shelves is directed to optoelectronic sensor elements for recording an image by an imaging optical device. The recording of every image is adapted to the reflectance ratios at the front sides which contribute to the imaging. The device and method is applicable in the manufacture of integrated circuits.