Patent ID: 7108476

Claim:
An apparatus for accessing and gripping disc-shaped wafers supported in a housing and having peripheral position indicators, comprising: a rigid support structure, said rigid support structure being dimensioned to enable movement into and out of said housing between adjacent wafers without physically engaging said wafers; a plurality of rotatable wafer supports mounted on said rigid support structure at locations selected so as to support a said wafer on said rigid support structure only around its periphery; a rotatable driver mounted on said rigid structure at a position to engage said periphery of said wafer when supported by said rotatable wafer supports, and selectively operable to rotate said wafer while supported by said rotatable wafer supports to a selected radial position; and a first optical detector mounted on said rigid support structure, said first optical detector being operable to detect when said wafer is in said selected radial position and to generate a signal indicating the same.