| 摘要 |
A monitoring device for determining the presence or absence of wafer-like objects in a carrier having a plurality of shelves, each shelf being constructed to support one such object in an orientation normal to a carrier axis. The monitoring device may advantageously be used in an apparatus for handling wafer-like objects in a self-contained environment. The monitoring device includes a first detector capable of detecting movement of a body past the detector and generating a corresponding first signal. A translation member is physically coupled to the carrier, such that movement of the translation member results in movement of the carrier. The translation member is moved such that the carrier, and any objects such as wafers supported in the carrier, move along the carrier axis past the first detector. As the translation member moves, a position signal is generated, such that the position signal encodes the position of the translation member. The first detection signal and the position signal are processed to determine the presence or absence of an object on each shelf, and the position of each object. A second detector may be employed to determine whether each object is fully seated in its shelf.
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