Displacement Uncertainty in Interferometric Radius Measurements
William T. Estler, Tony L. Schmitz, Angela Davies, Christopher J. Evans
Interferometric radius measurements may be completed using a radius bench, where radius is defined as the displacement between the confocal and cat''s eye nulls (identified using a figure measuring interferometer). Measurements of a Zerodur sphere have been completed on the X-ray Optics Calibration Interferometer (XCALIBIR) and a coordinate measuring machine. Recorded disagreements, larger than the uncertainty indicated by the current analysis, call for an exploration of the analysis model. This paper focus on uncertainties associated with the three displacement measuring interferometers (DMIs) equally spaced around XCALIBIR''s optical axis, but may be generalized to treat displacement uncertainty in any axis where multiple DMIs are used.