
136 ◾ Kieran G. Larkin
the root mean square (rms) errors for the Hilbert demodulator are more
than 10 times those of the SPT demodulator, as shown in Table4.1. Spectra
of the FTM and vortex methods are compared to the ideal in Figure 4.9.
e FTM spectral discrepancy is clear in this instance, whereas the vortex
method is indistinguishable from the ideal.
(a)
(b)
FIGURE 4.7 Demodulated quadrature fringe patterns compared to idealized
sinusoid: (a) ideal; (b) vortex; (c) Hilbert.