US Patent 7277183 Vibration resistant interferometry

A method includes providing scanning interferometry data for a test object, the data including intensity values for each of multiple scan positions for each of different spatial locations of the test object, the intensity values for each spatial location defining an interference signal for the spatial location, the intensity values for a common scan position defining a data set for that scan position. The method includes providing a scan value for each scan position, wherein increments between the scan values are non-uniform, transforming at least some of the interference signals into a frequency domain with respect to the scan values, and determining information about the test object based on the transformed interference signals.