Repeatability analysis of one-dimensional angular-measurement-based stitching interferometry.

ABSTRACT

Recently we presented one-dimensional Angular-measurement-based Stitching Interferometry (ASI) technique for synchrotron mirror metrology coupling an autocollimator and a white light interferometer. In this work, we conduct a further study on the measurement repeatability of this technique under different conditions, e.g. different scanning time or lengths with/without system drift. The similarity between the angle measuring stitching technique in ASI and the slope integration technique in deflectometry is addressed. The analytic expression of the height repeatability is derived while the slope noise is a zero-mean uncorrelated additive noise. In addition, we use a set of typical stationary signals from the autocollimator and the white light interferometer in a real experiment to simulate numerous virtual scans for the numerical calculation of the measurement repeatability under different measurement conditions. The simulation result predicts a link between the measurement repeatability and the scanning time with a constant speed. Moreover, it indicates that the major factor affecting the repeatability of our current ASI system is the system drift error.