Simultaneous measurement of in-plane and out-of-plane displacements using pseudo-Wigner-Hough transform

A new method based on pseudo-Wigner-Hough transform is proposed for the simultaneous measurement of the in-plane and out-of-plane displacements using digital holographic moire. Multiple interference phases corresponding to the in-plane and out-of-plane displacement components are retrieved from a single moire fringe pattern. The segmentation of the interference field allows us to approximate it with a multicomponent linear frequency modulated signal. The proposed method accurately and simultaneously estimates all the phase parameters of the signal components without the use of any signal separation techniques. Simulation and experimental results demonstrate the efficacy of the proposed method and its robustness against the variations in object beam intensity. (C) 2014 Optical Society of Americ

Fringe Projection Techniques: Whither we are?

During recent years, the use of fringe projection techniques for generating three-dimensional (3D) surface information has become one of the most active research areas in optical metrol-ogy. Its applications range from measuring the 3D shape of MEMS components to the measurement of flatness of large panels (2.5 m ×.45 m). The technique has found various ap-plications in diverse fields: biomedical applications such as 3D intra-oral dental measurements [1], non-invasive 3D imag-ing and monitoring of vascular wall deformations [2], human body shape measurement for shape guided radiotherapy treat-ment [3, 4], lower back deformation measurement [5], detection and monitoring of scoliosis [6], inspection of wounds [7, 8] and skin topography measurement for use in cosmetology [9, 10, 11]; industrial and scientific applications such as char-acterization of MEMS components [12, 13], vibration analy

Piecewise polynomial phase approximation approach for the analysis of reconstructed interference felds in digital holographic interferometry

This paper proposes a new approach for the analysis of reconstructed interference fields in digital holographic interferometry. In the proposed approach the interference phase to be estimated is conceived as a piecewise polynomial signal; consequently, each segment of the reconstructed interference field is modeled as a polynomial phase signal (PPS) with constant or slowly varying amplitude. The unwrapped phase distribution is then directly computed using the maximum likelihood estimation. Salient features of the proposed approach are: it provides accurate phase estimation from a single record of the interference field; it avoids cumbersome and error- prone filtering and 2D unwrapping procedures; and it paves the way to adapt well-established PPS analysis tools available in signal processing literature for the phase estimation in holographic interferometry

Numerical analysis of fringe patterns recorded in holographic interferometry using high-order ambiguity function

This letter introduces a new approach for the demodulation of fringe patterns recorded in holographic interferometry using high-order ambiguity function (HAF). The proposed approach is capable of retrieving the phase from a single fringe pattern. The main advantage of this approach is that it directly provides an estimation of the continuous phase distribution and thereby avoids the necessity of using a cumbersome 2D phase unwrapping procedure. This method first computes the discrete-time analytic signal of the recorded fringe pattern. Then, by modelling this analytic signal as a polynomial phase signal embedded in additive complex white Gaussian noise, a parametric estimation procedure based on HAF is employed to directly estimate the unwrapped phase distribution. Numerical simulations and experimental results demonstrate the potential of the proposed approach