Two procedures are presented that allow for unambiguous separation of misalignment from misfigure in off-axis asphere interferograms. In the first method the coma observed is used to locate the element, while in the second method the element is located by minimizing the observed mean-square wavefront error. With either procedure, the misalignment-induced aberrations can be calculated and subtracted from the interferogram so that only true misfigure remains.
Gregory C. Dente,
"Separating Misalignment From Misfigure In Interferograms On Off-Axis Aspheres", Proc. SPIE 0429, Precision Surface Metrology, (15 November 1983); doi: 10.1117/12.936359; https://doi.org/10.1117/12.936359