Use of modulated reference wave in electronic speckle pattern interferometry

Application of phase shifting electronic speckle pattern interferometry in studies of photoinduced shrinkage of photopolymer layers

“…Lokberg [8] reported the use of a phase shifting technique in speckle interferometry to measure object displacement. Moving a mirror in the reference beam path by means of piezoelectric transducer is one of the most common techniques [9,10] for phase shifting. Phase shifting electronic speckle pattern interferometry was the technique of choice in this study because of its whole field and near real-time capability.…”

Optical Techniques for Defect Evaluation in Vehicles

“…Later group pursued the development of the ESPI technique, with Lökberg (Lökberg O. et al, 1976;Lökberg O., 1985) and Beidermann (Beidermann et al, 1975) being important references in this field.…”

Experimental Measurements by an Optical Method of Resonant Frequences and Mode Shapes for Square Plates With Rounded Corners and Chamfers

“…The disadvantage of this method is that the interferometric fringes represent the amplitude but not the phase of the vibration. To improve this shortcomings the phase-modulation method using the reference beam modulation technique, was developed to determine the relative phase of displacement [4,5]. Shellabear and Tyrer [6] used ESPI to carry out three-dimensional vibration measurements.…”