NORAMET comparison of gauge block measurement by optical interferometry

A varied assortment of forty-seven new and used steel, ceramic, chromium ca rbide and tungsten carbide gauge blocks from nine manufacturers, ranging in length from 0.5 mm to 101.6 mm, were calibrated by four laboratories from the NORAMET countries using the method of optical interferometry. Measureme nts of central length of the gauge blocks are compared. The data are utiliz ed as a test bed to illustrate the outcome of two different techniques with potential for application in comparisons of the calibration services of na tional metrology institutes (NMIs).