UNCERTAINTY ANALYSIS OF A TWO-PROBE INSTRUMENT FOR THE MEASUREMENT OF CENTER THICKNESS (CT) OF LENS ELEMENTS

摘要

In the paper, the parameter of interest, i.e., the center thickness is defined at the outset. This is followed by the development of the model equation for the measurement. The measurand is related implicitly to the influence quantities in the model equation and while an explicit form of the equation may be derived, it is cumbersome and no amenable to a GUM style uncertainty analysis. A Monte Carlo simulation is used to estimate the mean and the combined standard uncertainty of the measurand and results of the simulation for a typical case are presented. The measurand is evaluated using a root-finding technique as an explicit expression for the measurand is not available. The effect of uncertainty contributors with single-sided distributions is highlighted.