WRINGING DEFORMATION AND ROUGHNESS ASPECTS IN OPTICAL LENGTH MEASUREMENTS

Texture deformations of gauge block surfaces arising in the wringing contact between similar structures have been determined for the first time using atomic force microscopy and optical interferometry. The level of deformations is shown to be dependent on the surface structure, and for modern gauge blocks is about 3 nm, only. Using new parallax-free methods of interferometric length measurements, roughness contribution to the measurement result by optical interferometry have been measured with a few nanometer uncertainty level.