Quiroga Mellado, Juan AntonioEstrada, Julio CésarServín Guirado, Manuel2023-06-202023-06-202009-09-141094-408710.1364/OE.17.016423https://hdl.handle.net/20.500.14352/43974© 2009 Optical Society of America. We acknowledge the valuable support of the Mexican Science Council, CONACYT.Systematic spectral analysis of Phase Shifting Interferometry (PSI) algorithms was first proposed in 1990 by Freischlad and Koliopoulos (F&K). This analysis was proposed with the intention that "in a glance" the main properties of the PSI algorithms would be highlighted. However a major drawback of the F&K spectral analysis is that it changes when the PSI algorithm is rotated or its reference signal is time-shifted. In other words, the F&K spectral plot is different when the PSI algorithm is rotated or its reference is time-shifted. However, it is well known that these simple operations do not alter the basic phase demodulation properties of PSI algorithms, except for an unimportant piston. Here we propose a new way to analyze the spectra of PSI algorithms which is invariant to rotation and/or reference time-shift among other advantages over the nowadays standard PSI spectral analysis by F&K.engjournal articlehttp://dx.doi.org/10.1364/OE.17.016423http://www.opticsinfobase.org/open access535InterferometryÓptica (Física)2209.19 Óptica Física