A comparison of stylus and optical methods for measuring 2D surface textures.

Due to the demanding dimensional specifications required by modern precision products a wide range of instruments and methods are being developed to establish an appropriate metrology infrastructure for surface texture. Increasingly, surfaces are being measured using non-contact optical probing techniques for which there are no internationally recognised specification standards. This lack of specification standards and other issues of calibration, along with the multitude of measuring instruments available, mean that it is difficult to obtain traceability to the definition of the metre. This report presents the results of a comparison of optical and stylus instruments. The National Physical Laboratory, two universities and four instruments manufacturers measured a ceramic sample and nickle sinusoidal grating. The results show alarming differences between instruments based on different measuring principles and instruments using the same measuring principles.