**9. References**


unsteady wake flows. At present, a specific setup of digital holographic interferometry has been defined in a single sight direction, and the aim will be to reproduce the same optical setup along several sight directions, each shifted by a given angle. It is obvious that the optical setup can be reproduced no more than three or four times. But the lack of sight directions should be compensated by high tomographic interferogram resolution for the

The author thanks Jean-Louis Tribillon, retired, from Délégation Générale à l'Armement and Félix Albe, retired, from Institut Franco-Allemand de Recherches de Saint-Louis for their collaboration for developing the transmission and reflection holographic interferometers. A great thank also to Professor Pascal Picart from Laboratoire d'Acoustique du Maine for the implementation of digital holographic interferometry in ONERA. The section 6 of this research has been funded from the French National Agency for Research (ANR) under grant

Bjelkhagen, H.I. & Vukicevic, D. (1992). Lippmann color holography in single-layer silver-

Bjelkhagen, H.I. (1993). Silver-halide recording-materials for holography and their

Bjelkhagen H.I., Jeong, T.H. & Vukicevic, D. (1996). Color reflection holograms recorded in a

Bjelkhagen, H.I. & Mirlis, E. (2008). Color holography to produce highly realistic three-

Cha, D.J. & Cha, S.S. (1996). Holographic interferometric tomography for limited data

Demoli, N., Vukicevic, D. & Torzynski, M. (2003). Dynamic digital holographic interferometry with three wavelengths, *Optics Express*, Vol.11, pp. 767-774. Desse, J.M. (1990). Instantaneous density measurement in two-dimensional gas flow by high speed differential interferometry, *Experiments in Fluids*, Vol.9, pp. 85-91 Desse, J.M. (1997a). Recording and processing of interferograms by spectral characterization of the interferometric setup, *Experiments in Fluids*, Vol.23, pp. 265-271 Desse, J.M. (1997b). Three-color differential interferometry, *Applied Optics*, Vol.36, pp. 7150-

Desse, J.M. (2006). Recent contribution in color interferometry and applications to high-

Desse, J.M., Picart, P. & Tankam, P. (2008). Digital three-color holographic interferometry for

Desse, J.M., Picart, P. & Tankam, P. (2010). Digital Three-Color Holographic Interferometry

Devoted to Fluid Mechanics, *Optical metrology*, Speckle 2010 7387, 73870S1-73870S6

speed flows, *Optics and Lasers in Engineering*, Vol.44, pp. 304-320

*Imaging Sciences and Technology*, Vol.40, pp. 134-146

reconstruction, *AIAA Journal*, Vol.34, pp. 1019-1026

flow analysis, *Optics Express*, Vol.16, pp. 5471-5480

dimensional images, *Applied Optics*, Vol.47, pp. A123-A133

halide emulsion, *5th International Symposium On Display Holography*, T. H. Jeong ed.

processing, *Springer Series in Optical Sciences*, Vol.66, Springer Verlag New-York,

panchromatic ultra high-resolution single-layer silver-halide emulsion", *Journal of* 

reconstruction of the 3D gas density field.

agreement n° ANR 2010 BLAN 0302.

ISBN 3-540-58619-9.

Proc. SPIE Vol.2333, pp. 34-48

**8. Acknowledgments** 

**9. References** 

7156


**2** 

*Japan* 

**Three-Dimensional Displacement and** 

It is important to measure displacement and strain distributions to prevent failures of structures. However, one point measurement method such as strain gage is widely used in industrial practice. It is time–consuming and difficult for one-point method to find the point with the maximum strain on the structures. Whole-field optical methods such as moire method, digital image correlation, speckle method and holography are effective to find the point with the maximum strain (Sharpe, 2008). Especially, holography provides three

In conventional holography, an object beam and a reference beam interfere each other on a high-resolution photographic plate. It is necessary to develop the photographic plate (hologram) and it is time-consuming and bothersome work. In conventional holographic interferometry, holograms recorded before and after deformation are superposed on a photographic plate and the displacement is obtained from the interference fringe pattern (Valery et al., 1996; Ranson et al., 1993; Hayashi et al. 1986). In digital holography, a hologram is usually recorded on a CCD or C-MOS sensor instead of a photographic plate (Yaroslavskii et al., 1980; Pedriniet al., 1998; Schnars, et al. 2005). In phase-shifting digital holographic interferometry (PSDHI), the complex amplitude of the object is analyzed from the phase-shifted holograms obtained by shifting the phase of the reference beam. The reconstructed image can be calculated from the complex amplitudes of the hologram using the Fresnel diffraction integral with a computer (Yamaguchi et al., 1997; Zhang et al., 1998). The displacement at each point of an object is obtained from the phase-difference between the reconstructed images analyzed from the digital holograms recorded before and after deformation. The equipment is simple and the analysis is fast. It is useful for practical field

Holograms and reconstructed images have speckle noise and they provide large error in the calculation of displacement and strain analysis. In order to reduce the effect of speckle noise, the authors developed a novel method, i.e., the windowed phase-shifting digital holographic interferometry (Windowed PSDHI). In holography, any part of a hologram has the optical information about the whole reconstructed image. By using this feature of

dimensional displacement information and high resolution.

measurement of displacement and strain distributions.

**1. Introduction** 

 **Strain Measurements by Windowed** 

 **Phase-Shifting Digital** 

**Holographic Interferometry** 

*Moire Institute Inc. & Wakayama University* 

Yoshiharu Morimoto and Motoharu Fujigaki

