Patent ID: 7173691

Claim:
In a metrology system including a part-positioning means having a spindle axis and a wavefront-measuring gauge, a part-on-mount method for determining the misalignment of a test part with respect to the spindle axis, and the misalignment of the spindle axis with respect to the wavefront-measuring gauge, the method comprising the steps of: a) mounting said test part onto said spindle axis such that a surface of said test part is exposed to said gauge; b) obtaining measurements of said test part surface with said gauge at a plurality of rotary positions of said spindle; c) extracting tilt components from said surface measurements at each of said rotary positions; d) fitting a circle to said tilt components and said rotary positions; e) determining the center of said circle with respect to said spindle to provide said gauge-to-spindle misalignment; and f) determining the radius coordinates of said circle with respect to said spindle to provide said spindle-to-part misalignment.