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Two cases of phase-shifting interferometry for wave front recovery from heterodyne hologram storage: piezoelectric transducer and modulation of polarization

Rodríguez-Zurita G., Vázquez-Castillo J. F., Toto-Arellano N. I., Calderón-Hernández G., Barojas-Gutiérrez E.

Optica Applicata

2017

Vol. 47, nr 4

579-590

Heterodyne holographic interferometry is a well-known interferometric technique for high precision measurements of the phase difference between two recorded wave fronts. These wave fronts are typically registered at a given distance from the object under inspection. Although the affinity of heterodyne techniques with the phase-shifting ones is immediate, reports on concrete implemented set-ups from the former type of techniques as adaptations into the second type seems to be not so widely spread as convenient. To illustrate this point, in this communication we demonstrate two phase-shifting methods as applied to heterodyne holograms, each variant using a different shifting method for phase shifting. One method is based on a conventional piezoelectric stack transducer and the other method comprises modulation of polarization. The alternatives that these two techniques offer could be of direct benefit in dynamic holography.

A method for improving the precision of on-line phase measurement profilometry

Mao Z, Cao Y, Zhong L, Cao S

Optica Applicata

2015

Vol. 45, nr 1

51—61

An on-line phase measurement profilometry based on improved Stoilov’s algorithm is proposed to measure the 3D shape of moving object. While only one frame sinusoidal grating is projected on the moving object, the equal phase-shifting step deformed patterns modulated by profile of the measured object can be captured at every equivalent moving distance of the measured object instead of digital phase-shifting. Stoilov’s algorithm is an equal phase-shifting step algorithm at an arbitrary phase-shifting step, which is suitable for on-line phase measurement profilometry. However, the arbitrary phase-shifting step of Stoilov’s algorithm depends on the captured deformed patterns, in which the digitized errors of digital light projector or CCD camera, and the disturbance of surrounding light could be introduced, it will lead to some abnormities in wrapped phase, such as the denominator in Stoilov’s algorithm could be zero, which could cause the reconstructed 3D profile of the measured object appear burr, distortion or aberration, even could not be reconstructed. So an on-line phase measurement profilometry based on improved Stoilov’s algorithm is proposed. The arbitrary phase-shifting step is retrieved by both pixel matching and fringe cycle calibration rather than the captured deformed patterns. Experiments verify the feasibility and effectiveness of the proposed on-line phase measurement profilometry.