SELF-ZERO-ADJUSTMENT OF PROBES IN THE METHODS CONSTRUCTING SOFTWARE DATUM FOR LARGE PROFILE MEASUREMENT

This paper presents a new technique to estimate zero-adjustment errors of multiple probes which are used to construct software datum for lar ge profile measurements. Three kinds of software datum are considered, which are the 3-point method, the differential laser autocollimation (DLA) method and the mixed method, respectively. The proposed new tech nique can estimate the zero-adjustment error by using only the data of profile measurement of the workpiece. Therefore it does not require a ny reference surface or any reversal measurement process. This paper d iscusses the accuracy and the reliability of the proposed technique in the profile measurement of a large mirror with a length of about 1 m through theoretical analyses and computer simulations. An experimental system of profile measurement using the DLA method was also construct ed.