Fourier-Transform Evaluation Of Interference Patterns: The Role Of Filtering In The Spatial Frequency Domain

The Fourier-transform method pointwisely determines the interference phase distribution out of a single digitally recorded and stored interference pattern. By using suitable filter parameters in the spatial frequency domain, speckle noise and known as well as unknown background variations can be suppressed. The paper presents a description of the Fourier-transform method, a discussion of the effects of filter parameters like orientation and cutoff-frequencies, and experimental results.