Surface profiling using shearography

We review profile measurement methods using shearography. Traditionally, shearography implies the use of small image shearing, which yields first-order derivatives of displacements or of spatial coordinates. We demonstrate that the use of large image shearing is equivalent to holography, since displacement-related, or spatial coordinate-related, phase fringes are generated. Hence, the technique of shearography can appropriately be perceived as an optical technique that directly measures displacements (or spatial coordinates) and surface strains (or surface slopes). Unlike holography, shearography does not require special vibration isolation since a separate reference beam is not required; hence, it is a practical tool that can be used in the field/ factory environment. Examples of the use of small and large image shearing for surface profiling are given. Finally, a novel method for computing phase derivatives for the determination of curvatures of object surfaces from shearographic measurements is discussed.

[1]  J. Leendertz,et al.  An image-shearing speckle-pattern interferometer for measuring bending moments , 1973 .

[2]  T. Hsu,et al.  Mechanics of sheet metal formed by hydraulic pressure into axisymmetrical shells , 1976 .

[3]  Y. Y. Hung,et al.  Optical method for measuring contour slopes of an object. , 1978, Applied optics.

[4]  Y. Y. Hung,et al.  Image-shearing camera for direct measurement of surface strains. , 1979, Applied optics.

[5]  Y. Y. Hung,et al.  Simultaneous measurement of three displacement derivatives using a multiple image-shearing interferometric camera , 1979 .

[6]  Y. Y. Hung.  Shearography: A New Optical Method For Strain Measurement And Nondestructive Testing , 1982 .

[7]  T. Hsu,et al.  Curvatures and Membrane Stresses in Pressure Vessel Heads , 1984 .

[8]  Y. Y. Hung,et al.  Direct Measurement of Flexural Strains in Plates by Shearography , 1986 .

[9]  C. Tay,et al.  Estimating the depth and width of arbitrarily-oriented disbonds in laminates using shearography , 1990 .

[10]  C. Tay,et al.  Flaw detection in composites using time-average shearography , 1991 .

[11]  Y. Y. Hung,et al.  Three-dimensional shape measurement using digital shearography , 1995, Optics & Photonics.

[12]  F. Chau,et al.  Shearographic and Holographic Assessment of Defective Laminates With Bond-Lines of Different Elasticities , 1995 .

[13]  Pramod Rastogi,et al.  An electronic pattern speckle shearing interferometer for the measurement of surface slope variations of three-dimensional objects , 1997 .

[14]  C. J. Tay,et al.  Cross influence of coordinate and slope related fringes during shearographic profiling , 1997 .

[15]  J. D. Hovanesian,et al.  Residual stress evaluation using shearography with large-shear displacements , 1997 .

[16]  R. Tatam,et al.  Slope measurement by two-wavelength electronic shearography , 1997 .

[17]  M. Hung,et al.  Measurement of residual stress by phase shift shearography , 1997 .

[18]  P. Rastogi.  Determination of surface strains by speckle shear photography , 1998 .

[19]  Y. Y. Hung,et al.  Shearography for Rapid Nondestructive Evaluation of Bonded Composite Structures , 1999 .