In many fringe pattern processing applications the local phase has to be obtained from
a sinusoidal irradiance signal with unknown local frequency. This process is called
asynchronous phase demodulation. Existing algorithms for asynchronous phase
detection, or asynchronous algorithms, have been designed to yield no algebraic error
in the recovered value of the phase for any signal frequency. However, each
asynchronous algorithm has a characteristic frequency response curve. Existing
asynchronous algorithms present a range of frequencies with low response, reaching
zero for particular values of the signal frequency. For real noisy signals, low response
implies a low signal-to-noise ratio in the recovered phase and therefore unreliable results.
We present a new Fourier-based methodology for designing asynchronous
algorithms with any user-defined frequency response curve and known limit of
algebraic error. We show how asynchronous algorithms designed with this method
can have better properties for real conditions of noise and signal frequency variation.
© 2006 Optical Society of America
Equations on this page are rendered with MathJax. Learn more.