Error propagation in differential phase evaluation.

In many metrological applications the data being measured is associated to the phase difference codified in two fringe patterns. This phase difference can be recovered directly with what are called Differential Phase Shifting Algorithms (DPSAs) by using a combination of irradiance values from both patterns in the arctangent argument. Use of such algorithms requires characterisation mechanisms to inform of their sensitivity to the various random and systematic error sources, which is the same as for well-studied Phase Shifting Algorithms (PSAs).

Fourier analysis of two-stage phase-shifting algorithms.

Differential phase-shifting algorithms (DPSAs) and sum phase-shifting algorithms (SPSAs) recover directly the phase difference and the phase sum, respectively, encoded in two patterns. These algorithms can be obtained, for instance, by an appropriate combination of phase-shifting algorithms (PSAs), which makes unnecessary the previous calculation and subtraction or addition of each individual optical phase by means of conventional PSAs. A filtering process in the frequency domain is presented that allows us to obtain in a simple and elegant manner a qualitative characterization with a Fourier description of the two-stage phase-shifting evaluation that reveals possible phase shifter miscalibration errors and unexpected harmonics in the signal.

Enhancing the sensitivity to small phase changes in double-exposure stroboscopic television holography.

We present a new technique for enhancing the sensitivity of double-exposure stroboscopic television holography (TVH) to detect and measure vibrations of small amplitude. The technique is based in the modulation of the phase of the reference beam in synchronism with the vibration of the measurand and derives from a former technique that we originally contrived for phase evaluation. We propose two variants, characterized by the demodulation process used to generate the secondary correlograms, with different behaviors in terms of the sensitivity to the sign of the measurand and of the ease in detecting the presence and shape of the vibration.

Transient Deformation Measurement by Double-Pulsed-Subtraction TV Holography and the Fourier Transform Method.

We report the measurement of transient bending waves with double-pulsed-subtraction TV holography. The correlation fringe patterns are automatically quantitatively analyzed by the application of Fourier methods. A novel optical setup with two different object-beam optical paths is demonstrated for the generation of carrier fringes.

Multiplicative moiré two-beam phase-stepping and fourier-transform methods for the evaluation of multiple-beam fizeau patterns: a comparison.

A phase-evaluation method of multiple-beam Fizeau patterns that combines two-beam phase-stepping algorithms with the moiré effect was previously reported [Appl. Opt. 34, 3639-3643(1995)].