Patent ID: 8262072

Claim:
A work piece carrier adapted to be releaseably attached to a chuck member and having a central longitudinal Z axis, comprising: a central aperture extending in the direction of the central longitudinal axis and adapted to receive a work piece; a first reference system provided with first centering elements arranged to contact the chuck member when the workpiece carrier is attached thereto and adapted to align the work piece carrier with regard to the chuck member in a first accurately defined position; a second reference system provided with second centering elements arranged to contact the chuck member when the workpiece carrier is attached thereto and adapted to align the work piece carrier with regard to the chuck member in a second accurately defined position; a first protrusion associated with the first reference system for releaseably attaching the work piece carrier to the chuck member in a first position, said first protrusion surrounding the central aperture in the work piece carrier and extending substantially in the direction of the central longitudinal axis of the work piece carrier; and a second protrusion independent from the first protrusion and associated with the second reference system for releaseably attaching the work piece carrier to the chuck member in a second position different from said first position, said second protrusion surrounding the central aperture in the work piece carrier and extending substantially in the direction of the central longitudinal axis of the work piece carrier.