Electronic speckle pattern interferometry
This chapter describes the theory of electronic speckle pattern interferometry (ESPI); the technique can be considered the video equivalent of holographic interferometry (Leendertz, 1970; Butters and Leendertz, 1971; Ennos, 1975; Jones and Wykes, 1989). It generates fringe patterns where the fringe spacing is a function of laser wavelength and, since this wavelength is defined and stable, it therefore provides data which is absolute and does not require any form of calibration. Optical configurations can provide the three Cartesian displacements — out-of-plane (z), vertical and horizontal in-plane (x, y) — to be uniquely and independently acquired (Jones, 1976). These three individual maps of surface displacement can be combined to yield complete surface motion analysis without the need for any presurface treatment or contact (Moore and Tyrer, 1990; Shellabear and Tyrer, 1991). New techniques allowing automatic analysis without any operator involvement have overcome some of the problems associated with the large volumes of data acquired using interferometric techniques (Nakadate and Saito, 1985; Mendoza, Shellabear and Tyrer, 1991;Robinson and Reid, 1993).
KeywordsFringe Pattern Reference Beam Holographic Interferometry Electronic Speckle Pattern Interferometry Object Beam
Unable to display preview. Download preview PDF.
- Butters, J.N. and Leendertz, J.A. (1971) Holographic and video techniques applied to engineering measurement. Trans. Inst. Meas. Con., 4(12), 349–54.Google Scholar
- Ennos, A.E. (1975) Speckle interferometry, in Laser Speckle and Related Phenomena (ed. J.C. Dainty), Springer-Verlag, Berlin, pp. 203–53.Google Scholar
- Jones, R. and Wykes, C. (1989) Holographic and Speckle Metrology, 2nd edn, Cambridge University Press, Cambridge.Google Scholar
- Kerr, D., Mendoza, F. and Tyrer, J.R. (1990) Extraction of phase data from ESPI fringes using a single phase step method: a novel approach. J. Opt. Soc. Am. A, 7, 820–26.Google Scholar
- Mendoza, F., Shellabear, M.C. and Tyrer, J.R. (1991) Wholefield in-plane vibration analysis using pulsed phase stepped ESPI. Appl. Opt., 3(30), 717–21.Google Scholar
- Moore, A.J., Tyrer, J.R. and Mendoza-Santoyo, F. (1994) Phase extraction from electronic speckle pattern interferometric addition fringes. Appl. Opt., 31(33), 7312–20.Google Scholar
- Robinson, D.W. and Reid, G.T. (1993) Interferogram Analysis: Digital Fringe Pattern Measurement Techniques, IOP Publishing, Bristol.Google Scholar
- Tyrer, J.R. (1985) Application of pulsed holography and double pulsed electronic speckle pattern interferometry to large vibrating engineering structures. Proc. SPIE, 599, 181–8.Google Scholar
- Tyrer, J.R. (1987) Optical inspection using pulsed laser speckle interferometry. UK Patent 8 712 933.Google Scholar