Work piece carrier for exactly positioning a work piece on a chuck and clamping apparatus with a chuck and a work piece carrier

A clamping apparatus with a chuck member and a work piece carrier adapted to be releaseably attached to the chuck member, said chuck member having a reference system for defining the position of a work piece carrier attached to the chuck member as well as clamping elements for clampingly hold a work piece carrier attached to the chuck member, said work piece carrier having a central longitudinal axis and 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 and adapted to cooperate with the reference system of the chuck member 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 and adapted to cooperate with the reference system of the chuck member to align the work piece carrier with regard to the chuck member in a second accurately defined position;
• a first protrusion assigned to 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, extending substantially in the direction of the central longitudinal axis of the work piece carrier, and having a clamping surface adapted to be engaged by the clamping elements of the chuck member;
• and
• a second protrusion independent from the first connecting means and assigned to 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, extending substantially in the direction of the central longitudinal axis of the work piece carrier, and having a clamping surface adapted to be engaged by the clamping elements of the chuck member.