  Synthesis of single-wavelength temporal phase-shifting algorithms (PSA) for
interferometry is well-known and firmly based on the frequency transfer
function (FTF) paradigm. Here we extend the single-wavelength FTF-theory to
dual and multi-wavelength PSA-synthesis when several simultaneous laser-colors
are present. The FTF-based synthesis for dual-wavelength PSA (DW-PSA) is
optimized for high signal-to-noise ratio and minimum number of temporal
phase-shifted interferograms. The DW-PSA synthesis herein presented may be used
for interferometric contouring of discontinuous industrial objects. Also DW-PSA
may be useful for DW shop-testing of deep free-form aspheres. As shown here,
using the FTF-based synthesis one may easily find explicit DW-PSA formulae
optimized for high signal-to-noise and high detuning robustness. To this date,
no general synthesis and analysis for temporal DW-PSAs has been given; only
had-hoc DW-PSAs formulas have been reported. Consequently, no explicit formulae
for their spectra, their signal-to-noise, their detuning and harmonic
robustness has been given. Here for the first time a fully general procedure
for designing DW-PSAs (or triple-wavelengths PSAs) with desire spectrum,
signal-to-noise ratio and detuning robustness is given. We finally generalize
DW-PSA to higher number of wavelength temporal PSAs.
