Real-time color holographic interferometry

Abstract

A new optical technique based on real-time color holographic interferometry has been developed for analyzing unsteady aerodynamic wakes in fluid mechanics or for measuring displacements and deformations in solid mechanics. The technique's feasibility is demonstrated here. It uses three coherent wavelengths produced simultaneously by a cw laser (mixed argon and krypton). Holograms are recorded on single-layer panchromatic silver halide (Slavich PFG 03C) plates. Results show the optical setup can be adjusted to obtain a uniform background color. The interference fringe pattern visualized is large and colored and exhibits a single central white fringe, which makes the zero order of the interferogram easy to identify. An application in a subsonic wind tunnel is presented, in which the unsteady wake past a cylinder is recorded at high rate.

Single Shot White Light Interference Microscopy for 3D Surface Profilometry Using Single Chip Color Camera

“…to avoid phase ambiguity [32,[46][47][48]. Figure 9(a) shows the height map for synthetic wavelength RG Λ and Fig.…”

“…In the recent past, the color CCD camera has been used to record the color interferogram and color fringe analysis using three laser sources [30][31][32][33] or used a phase crossing algorithm to find the phase from a single white light interferogram at a wavelength for which the phase difference between the red, green and blue parts of the white light fringes become equal to zero [34,35]. This has been extensively used in optical metrology for step height measurement.…”

“…A Hilbert transform was used to find the phase map corresponding to each color interferogram. The present technique for determining the wavelength dependent phase doesn't require multiple color laser sources, spectral filters and dispersive optical elements [30][31][32][33][34][35]. The system requires only a single chip color CCD camera, white light source and conventional optical microscope.…”

Analyse des écoulements instationnaires par interférométrie holographique numérique couleur (de la plaque holographique au numérique)

“…La relation de Gladstone Dale permet ensuite d'accéder à la masse volumique. Il y a quelques années, l'ONERA a déve-loppé pour l'analyse des écoulements instationnaires une métrologie optique basée sur l'interférométrie holographique analogique à trois longueurs d'onde utilisant des supports holographiques panchromatiques par transmission et par réflexion [1,2]. Le principal inconvénient de cette dernière métrolo-gie réside dans le contrôle de l'épaisseur de la gélatine des hologrammes pendant le développement des plaques et l'efficacité de diffraction de l'hologramme qui doit être voisine de 50 % simultanément pour les trois longueurs d'onde utilisées.…”

Pulsed Full-Color Digital Holography with a Raman Shifter

“…In optical metrology, a multi-wavelength light source enables measurements with variable resolution. During reconstruction in holographic interferometry, the zeroth-order fringe which indicates the reference undeformed region can be identified because of its white color that results from superposition of the primary colors used (Desse, et al, 2002;Jeong, 1999;Demoli, et al, 2003). Implementation of full-color holography has been constrained by several experimental issues.…”