Simultaneous 3D measurement of deformation and its first derivative with speckle pattern interferometry and shearography

Simultaneous three-dimensional deformation measuring based on a simple phase-shift device combination with tri-wavelength and three-CCD camera

“…However, to derive the 3D deformation information, one must solve three equations first and then obtain the displacement derivatives by an estimation operation replacing with numerical differentiation. Based on DS, ESPI, and tri-color, several approaches have been put forward for simultaneously measuring 3D displacement and its gradients 7 , 8 . In these methods, a Michelson-interferometer-type device was introduced to produce three shearograms using three lasers with different wavelengths.…”

“…For spatial methods of 3D deformation measurement, three different spatial carrier frequencies are introduced into the interference system, and Fourier transform (FT) method serves as a competing procedure for fringe pattern analysis 7 – 9 According to the Nyquist theorem, the spatial frequency must be at least twice that of the measured deformation, which limits the measuring range. Another disadvantage of FT for 3D deformation simultaneous measurement is the need for individually adapted filters in the spatial frequency domain.…”

“…Based on DS, ESPI, and tri-color, several approaches have been put forward for simultaneously measuring 3D displacement and its gradients. 7,8 In these methods, a Michelson-interferometertype device was introduced to produce three shearograms using three lasers with different wavelengths. These shearographic technique allows for simultaneously measuring three components of displacement gradients in a 3D view-field, but as is known, six components exist, and these methods have difficulty changing the shear amount and direction in dynamic or non-repeatable measurements.…”

Synchronous measurement of surface deformation and gradient distribution in microstructures

“…This method is very suitable for measurement of microstructure. 10 Some commonly used optical measurement technologies are holographic interferometry 11 and digital speckle pattern interferometry. 12 Digital speckle pattern interferometry is often applied for displacement measurement, strain analysis, dynamic testing, and nondestructive flaw detection of materials and structures in aerospace, automobile, ship manufacturing, and relevant other fields because it can cover a full-field, involves real-time measurement, capable of online detection, and has high sensitivity and high precision.…”

“…Optical measurement technology with interference technology has the advantages of noncontact process, quick measurement, and high precision. This method is very suitable for measurement of microstructure 10 . Some commonly used optical measurement technologies are holographic interferometry 11 and digital speckle pattern interferometry 12 .…”