Uncertainty of measurement of calibrated test lengths realised by interferometry in ISO 10360-2 testing

The ISO 10360 2 is concerned with testing CMMs (Coordinate Measuring Machines) using alternative calibrated test lengths, realised either by material standards or by interferometry. Whatever the calibrated test lengths, the ISO 10360 2 requires the evaluation of the test value uncertainty, and hence of its several components; one of them is the uncertainty in realising the calibrated test lengths. This technical report gives guidance on how to evaluate the uncertainty incurred in realising calibrated test lengths by interferometry, equivalent to the calibration uncertainty when the calibrated test lengths are realised by material standards. This uncertainty, u(int), is just a component of the overall test value uncertainty. Other components – such as clamping and overall alignment – are beyond the scope of this technical report. Readers are remembered not to overlook the other uncertainty components.