Abstract
ESPI is typically done using a single monochromatic light source with a monochrome camera. This arrangement enables full-field measurements of a single deformation quantity according to the particular arrangement of the optical system. If a further deformation quantity is to be measured, then the associated optical arrangement must be used sequentially. Here, an alternative approach is described where multiple interferometric measurements are simultaneously made using a color camera imaging monochromatic light sources of different wavelengths. The Red-Green-Blue (RGB) sensors of a conventional Bayer type camera can be read separately, thereby providing three independent color signals and independent ESPI phase maps. An example case is demonstrated here where two Michelson interferometers are combined to form a shearography camera with surface slope sensitivity in two perpendicular directions. By the use of two colors, both surface slopes can be measured simultaneously. The availability of the two surface slopes gives the opportunity for the data to be integrated numerically to give the surface displacement shape. This application is of significant practical interest because the surface displacement measurement can be made under field conditions by taking advantage of the well-known stability of shearography measurements.
This is a preview of subscription content, log in via an institution.
Buying options
Tax calculation will be finalised at checkout
Purchases are for personal use only
Learn about institutional subscriptionsReferences
Leendertz JA (1970) Interferometric displacement measurement on scattering surfaces utilizing speckle effect. J Phys E Sci Instrum 3(3):214–218
Butters JN, Leendertz JA (1971) Speckle pattern and holographic techniques in engineering metrology. Opt Laser Technol 3(1):26–30
Steinchen W, Yang L (2003) Digital shearography: theory and application of digital speckle pattern shearing interferometry. SPIE Press, Bellingham, WA, p 310
Hack E, Riner M (2001) 3D ESPI and 3D shearography measurements applied to NDT and FEM analysis validation for industrial quality control. Proc SPIE 4398:155–167
Burnett M, Bryanston-Cross PJ (1996) Measurements of transonic shock structures using shearography. Proc SPIE 2861:124–135
Hack E, Kaestle RP (1999) Multi-wavelengths shearography for optical whole-field strain measurements. In: Colloque Nouveaux Moyens Optiques Pour L’Industrie II, Mittelwihr/Colmar (F), Proceedings, 17–19 November 1999, pp 31–36
Bayer BE (1976) Color imaging array. US patent 3,971,065, US Patent and Trademarks Office, Washington DC, 1976
Georgas P, Schajer GS (2012) Simultaneous measurement of full-field vibration modes using ESPI. Exp Mech 53(8):1461–1466
Rastogi P, Hack E (2012) Optical methods for solid mechanics: a full-field approach. Wiley, Chichester
Yang LX, Steinchen W, Schuth M, Kupfer G (1995) Precision measurement and nondestructive testing by means of digital phase shifting speckle pattern and speckle pattern shearing interferometry. J Int Meas Confed 16(3):149–160
Sirohi RS, Chau FS (1999) Optical methods of measurement: wholefield techniques. Dekker, New York
An Y, Schajer GS (2011) Pixel quality evaluation and correction procedures in ESPI. Exp Tech 35(5):23–29
Giglia DC, Pritt MD (1998) Two-dimensional phase unwrapping: theory, algorithms, and software. Wiley-Interscience, New York
Pomeroy RJ (1970) The effect of anticlastic bending on the curvature of beams. Int J Solids Struct 6(2):277–285
Schnars U, Jüptner W (1992) Messung von Absolutverformungen mit Methoden der holografischen Interferometrie und der Elektronischen Specklemuster-Interferometrie. Laser und Optoelektronik 24(1):59–63
Marwitz H (1990) Holografische Konturgenerierung, Chapter 18 in Praxis der Holografie—Grundlagen, Standard- und Spezialverfahren, Marwitz, H (ed.) Expert Verlag, Stuttgart
Acknowledgments
The authors sincerely thank the Natural Sciences and Engineering Research Council of Canada (NSERC), American Stress Technologies, Inc., Pittsburgh, PA, and the Institute for Computing, Information and Cognitive Systems (ICICS), Vancouver, Canada, for financially supporting this research.
Author information
Authors and Affiliations
Corresponding author
Editor information
Editors and Affiliations
Rights and permissions
Copyright information
© 2015 The Society for Experimental Mechanics, Inc.
About this paper
Cite this paper
Richoz, G., Schajer, G.S. (2015). Simultaneous ESPI Measurements Using Multiple Wavelengths and a Color Camera. In: Jin, H., Sciammarella, C., Yoshida, S., Lamberti, L. (eds) Advancement of Optical Methods in Experimental Mechanics, Volume 3. Conference Proceedings of the Society for Experimental Mechanics Series. Springer, Cham. https://doi.org/10.1007/978-3-319-06986-9_41
Download citation
DOI: https://doi.org/10.1007/978-3-319-06986-9_41
Published:
Publisher Name: Springer, Cham
Print ISBN: 978-3-319-06985-2
Online ISBN: 978-3-319-06986-9
eBook Packages: EngineeringEngineering (R0)