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Residual flatness and scale calibration for a point autofocus surface topography measuring instrument

Maculotti, Giacomo; Feng, Xiaobing; Su, Rong; Galetto, Mauirizio; Leach, Richard K.


Giacomo Maculotti

Xiaobing Feng

Rong Su

Mauirizio Galetto


Point autofocus instruments are often used for measuring the surface topography of objects with complex geometry. Determining the metrological characteristics of the instrument is key to ensuring a traceable areal surface topography measurement. In this work, several metrological characteristics, as outlined in ISO/FDIS 25178-600, are determined for a commercial point autofocus instrument, including flatness deviation, the amplification and linearity of the lateral and vertical axes, and the perpendicularity between the axes. Calibrated material measures including an optical flat, step heights and areal cross gratings are used to determine the metrological characteristics. The impact of the point autofocus operating principle and the evaluation method on the metrological characteristics is discussed.


Maculotti, G., Feng, X., Su, R., Galetto, M., & Leach, R. K. (2019). Residual flatness and scale calibration for a point autofocus surface topography measuring instrument. Measurement Science and Technology, 30(7),

Journal Article Type Article
Acceptance Date Apr 11, 2019
Online Publication Date Apr 11, 2019
Publication Date Apr 11, 2019
Deposit Date May 3, 2019
Publicly Available Date May 3, 2019
Journal Measurement Science and Technology
Print ISSN 0957-0233
Electronic ISSN 1361-6501
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 30
Issue 7
Keywords metrological characteristics, flatness deviation, linearity, axis calibration, point autofocus instrument
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