System and method for recovering phase information of a wave front

Abstract

A system and method for recovery of phase information from recorded intensity values is disclosed. A phase filter, such as one or more dioptric lenses, is placed in the back focal plane (BFP) of a lens used for observing an object. The phase filter changes the phase of a wave front distribution in the BFP in a known manner. The system captures N different sets of intensity data in the image plane (IP) using N different phase filters or N phase distributions generated by an electronically variable phase filter. The N intensity images are used to obtain an estimate of the wave front at the BFP of the lens. This BFP wave front estimate is then used to generate N modified estimates of the wave front at the IP, each modified estimate corresponding to one of the N phase distributions of the BFP phase filter(s). In one implementation, the N modified IP estimates are corrected by replacing the estimated amplitudes with the actually measured ones for that image. The process is repeated iteratively until an error measure between the measured values and the synthetically generated ones falls below a known threshold. A separate intensity measurement of the wave front at the BFP can be used to speed up the convergence of the process. The resulting phase estimates can be used to display wave front information similar in appearance to holograms