Comparison between a white-light interferometer and a tactile formtester for the measurement of long inner cylindrical surfaces

Shape measurements of engineering surfaces are an interesting and important application for white-light interferometry (WLI). Due to some factors such as: (a) the high-processing speed, (b) the ability to measure a huge quantity of points of the evaluated surface, and (c) the non-contacting nature; WLI has become a valuable tool for practical applications. This paper shows the achieved comparison between a modified white-light interferometer and an established measurement system, namely a formtester with a tactile spherical stylus sensor, which is the most commonly used instrument in the industry. Furthermore, this paper shows that the combination between the modified white-light interferometer and an adequate measurement and processing strategy has enabled to obtain a good agreement between optical and tactile measurements of long inner cylindrical surfaces. A cloud of points (COP) measured with the modified white-light interferometer has presented a standard deviation of about 0.3 μm when it was compared with formtester measurement of the same parts.