In phase-shifting interferometry(PSI) the standard wave retrieval formulae are usually derived based on the condition of a plane reference beam normal to the recording plane.In practice,however,the reference wave may be a spherical wave or even have a slight inclination due to the imperfect collimation and coaxality of the optical system,which will introduce phase distortion for the reconstructed object wave-front.A simple digital processing algorithm without any additional measurement is propos...