Estimation and Improvement of Accidental and Systematic Errors in Profile Measurements Using Software Datum

Abstract

It is important for precision profile measurements in on-machine conditions to construct some accurate datum for scanning. A kind of inclination method using three or more displacement sensors was proposed recently for this purpose. However, its characteristics in relation with the spatial frequencies of the profile have not been considered precisely. The z-directional resolution power of the method has not been strictly estimated. In the present paper a new and general expression of the multiprobe methods, including the inclination method, is derived to estimate the errors in relation to spatial frequencies. In all these methods, a similar datum of the parabolic curve is introduced by data processing, which is called the software datum. The influence of accidental errors is theoretically clarified in relation to the spatial frequency of the probed profile. The meaning of zero adjustment of the sensors for software datum of the scanning method is also clarified. A procedure for achiering good zero adjustment is also presented.