  One of the major challenges of employing a dual-frequency phase-shifting
algorithm for phase retrieval is its sensitivity to noise. Yun et. al [H Yun, B
Li, S Zhang. 2017] proposed a dual-frequency method based on the Fourier
transform profilometry (FTP), yet the low frequency lobes are close to each
other for accurate band-pass filtering. In light of this problem, a novel
dual-frequency pattern based on the spatial-temporal fringes (STF) method is
developed in this paper. Three fringe patterns with two different frequency are
required. The low frequency phase is obtained from two low frequency fringe
patterns by the STF method, so the signal lobes can be extracted accurately as
they are far away from each other. The high frequency phase is retrieved from
another fringe pattern without the impact of the DC component. Simulations and
experiments are conducted to demonstrate the excellent precision of the
proposed method.
