US Patent 7379174 Wafer detecting device

Provided is a detecting device for an FIMS system, for easily and simply detecting a slip-out of a glass wafer from an FOUP or detective storage thereof. The detecting device includes a light transmission sensor and a light reflection sensor. A light emitting portion of the light reflection sensor, a light receiving portion thereof, and one of a light emitting portion of the light transmission sensor and a light receiving portion thereof are disposed on one surface side of a substrate to be detected in a position in which the substrate is located. The other of the light emitting portion of the light transmission sensor and the light receiving portion thereof is disposed on the other surface side of the substrate to be detected in the position in which the substrate is located.