Publications by Rajshekhar Gannavarpu

Fringe analysis methods for noninvasive metrology and precision engineering

2014

Phase estimation using a state-space approach based method

The paper demonstrates a phase estimation method in fringe analysis. The proposed method relies on local polynomial phase approximation and subsequent state-space formulation. The polynomial approximation of phase transforms phase extraction into a paramet ...

Elsevier2013

Multiple signal classification technique for phase estimation from a fringe pattern

Pramod Rastogi, Rajshekhar Gannavarpu

The paper introduces a multiple signal classification technique based method for fringe analysis. In the proposed method, the phase of a fringe pattern is locally approximated as a polynomial. The polynomial phase signal is then transformed to obtain signa ...

Optical Society of America2012

Estimation of multiple phases from a single fringe pattern in digital holographic interferometry

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

Simultaneous measurement of multidimensional displacements using digital holographic interferometry involves multi-directional illumination of the deformed object and requires the reliable estimation of the resulting multiple interference phase distributio ...

Optical Society of America2012

Fringe analysis: Premise and perspectives

Pramod Rastogi, Rajshekhar Gannavarpu

Elsevier2012

Phase Gradient Estimation Techniques in Fringe Analysis

Rajshekhar Gannavarpu

The thesis introduces novel techniques in the field of fringe analysis for direct estimation of phase gradients or derivatives. A pseudo Wigner-Ville distribution based method is proposed to reliably estimate the phase derivatives from a single fringe patt ...

EPFL2012

Fringe demodulation using the two-dimensional phase differencing operator

Pramod Rastogi, Rajshekhar Gannavarpu

The Letter proposes a method for phase estimation from a fringe pattern. The proposed method relies on a parametric approach where the phase is locally approximated as a two-dimensional (2D) polynomial, with the ensuing polynomial coefficients as the respe ...

Optical Society of America2012

Detection of defects from fringe patterns using a pseudo-Wigner-Ville distribution based method

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

The paper presents a method to identify defects from fringe patterns. In the proposed method, the phase derivatives are computed from a fringe pattern using the two-dimensional Pseudo-Wigner–Ville distribution. Since the phase derivative varies rapidly in ...

Elsevier2012

Simultaneous multidimensional deformation measurements using digital holographic moiré

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

This paper proposes an elegant technique for the simultaneous measurement of in-plane and out-of-plane displacements of a deformed object in digital holographic interferometry. The measurement relies on simultaneously illuminating the object from multiple ...

Optical Society of America2011

Estimation of dynamically varying displacement derivatives using fringe projection technique

Pramod Rastogi, Sai Siva Gorthi, Rajshekhar Gannavarpu

This paper presents a pseudo Wigner–Ville-distribution-based method in fringe projection for analyzing temporal behavior of the displacement derivative for a continuously deformed object. In the proposed method, a computer generated fringe pattern is proje ...

Optical Society of America2011