Uncertainty evaluation for measurements of peak-to-valley surface form errors

The peak-to-valley deviation of a surface from its specified form is a widely used, conceptually simple surface specification. Evaluating the uncertainty in PV is not so simple. In the presence of noise, the measured PV is always too large. This paper shows an approach to correcting that bias. A number of error sources in interferometric testing of surfaces result in errors that have spatial variations across the aperture under test. Uncertainty in the correction of these errors, for example, leads to uncertainties test vary with position. This paper offers a procedure for evaluating the uncertainty in PV in this case. (C) 2008 CIRP.