A TYPICAL STAR PROBE HAS FIVE PROBE SPHERES THAT MUST ALL BE CHARACTERIZED IN ORDER TO FULLY UTILIZE THE PROBE. IN ORDER TO REACH AROUND, OVER AND UNDER ALL OF THESE SPHERICAL CONTACTS WITHOUT MOVING THE CALIBRATION SPHERE ALL OVER THE PLACE; A MULTI-SPHERE ARTIFACT MUST BE USED.

BY UTILIZING A SET OF FIVE EXACTLY MATCHED CALIBRATION SPHERES THAT ARE ARRANGED ON ORTHOGONAL PLANES, THIS JOB CAN BE DONE WITH RELATIVE EASE. BY BUILDING ONE ULTRA PRECISE, ULTRA RIGID UNIVERSAL ARTIFACT THAT CAN BE USED FOR CALIBRATING EVEN THE MOST COMPLEX STAR PROBES; WE HAVE ARRIVED AT AN ECONOMICAL APPROACH TO THIS DILEMMA. MANY DIFFERENT DIAMETER SPHERICAL ARTIFACTS CAN BE USED; BUT THE MOST POPULAR ARE THREE QUARTERS OF AN INCH 0.750 ( 19.05MM ) AND ONE INCH 1.00 ( 25.4MM ).