Patent ID: 6523426
Filing Date: 2003-02-25
Classification: G01N

Abstract:
Measuring apparatus comprising:a wafer located between first and second â€˜Oâ€™ rings, said first â€˜Oâ€™ ring being disposed on a first side of said wafer and said second â€˜Oâ€™ ring being disposed on a second side of said wafer opposite to said first side, said first and said second â€˜Oâ€™ rings being arranged such that in use a central portion of said first side of said wafer and a central portion of said second side of said wafer being of substantially the same diameter and opposite said central portion of said first side are exposed to substantially equal pressure and any remaining portions of said first and said second sides located outside said central portions are exposed to substantially equal pressure; a mechanical device arranged to hold said wafer proximate a distal end thereof by means of said first â€˜Oâ€™ ring and said second â€˜Oâ€™ ring, said first and said second â€˜Oâ€™ rings being removably attached to a first and a second â€˜Oâ€™ ring holding means respectively, with said first â€˜Oâ€™ ring holding means being substantially fixed to said distal end of said mechanical device, and said second â€˜Oâ€™ ring holding means being substantially fixed to a detachable block means which is arranged to be held in place at said distal end of said mechanical device, such that said wafer is held proximate said distal end of said mechanical device; wherein, said first â€˜Oâ€™ ring holding means further includes a plurality of pins disposed within a circular area defined by said first â€˜Oâ€™ ring and which corresponds substantially with said central portion of said first side of said wafer; and said plurality of pins are arranged to facilitate electrical contact between a plurality of electrical contact points disposed on said first side of said wafer and further electrical contacts disposed within said mechanical device.