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The Speckle Phenomenon
Published in Hector J. Rabal, Roberto A. Braga, Dynamic Laser Speckle and Applications, 2018
Néstor Gustavo Gaggioli, Juan Antonio Pomarico
Another approach in the field of speckle metrology, known as speckle interferometry, was first proposed by Leendertz39 at the beginning of the 1970s; in it the desired information is codified in the correlation fluctuations of the involved speckle patterns. This technique, together with the fast development of computers and image-processing systems, such as digital cameras and frame grabbers capable of many built-in operations, allowed the appearance of the first optodigital devices, leading to a technique known today as electronic speckle pattern interferometry (ESPI) or, alternatively, as TV holography. ESPI was first proposed at Loughborough University, England42 and simultaneously in Standford in the United States43 as an attempt to simplify the rather cumbersome and slow procedures of speckle photography involving chemicals to develop the plates and films. Since the late 1980s, ESPI has been used as an invaluable tool in research and industry to carry on nondestructive testing.44
Multi-label classification algorithms for composite materials under infrared thermography testing
Published in Quantitative InfraRed Thermography Journal, 2022
Muflih Alhammad, Nicolas Peter Avdelidis, Clemente Ibarra Castanedo, Xavier Maldague, Argyrios Zolotas, Ebubekir Torbali, Marc Genest
The inspection of composite materials using IRT has been of interest for a considerable period. For instance, Andrzej et al. [2] undertook an investigation for the damage identification in aircraft composite structures. Authors employed Piezoelectric Transducers (PZT) sensing, Ultrasonic, and PI for monitoring aircraft elements in varying environmental conditions. The detection of defects using the Infrared Thermography (IRT) was also investigated by Péronnet et al. [3]. In this investigation, three infrared thermographic techniques; IRT, Lock-in IRT and Pulse IRT, were applied to different types of composites that are used in aviation industry. Montanini [4] also used lock-in and pulse phase infrared thermography to quantify subsurface defects in a reference specimen that was made out of Plexiglas. Thermal images recorded at different frequencies (frequency domain) were post-processed and direct measurement of material’s thermal diffusivity was undertaken. Comparative results investigation between IRT and Electronic Speckle Pattern Interferometry (ESPI) for the NDT&E of Aircraft composites was undertaken by Findeis et.al [5]. Castanedo et al. [6] carried out another comparative study for the inspection of aerospace materials using pulsed thermography, lock-in thermography and vibrothermography. Pulsed thermography method was also employed by Bendada et al. [7] for the evaluation of aircraft composites. Hung et al. [8] presented a review and comparison investigation between shearography and active thermography for non-destructive and evaluation applications.
Velocity measurement of MEMS with temporal heterodyne microscopic speckle interferometry
Published in Journal of Modern Optics, 2021
Chenjia Gao, Zhan Gao, Yuhao Niu, Xu Wang, Jieming Zhao, Lin Deng
The micro measurement technologies based on scanning electron microscope (SEM) [4], atomic force microscope (AFM) [5–7] and scanning tunnelling microscope (STM) [8] inspection platforms have been well developed. In particular, many advances have been made in microelectronic chip detection, local deformation, and mechanical behaviour measurement. However, these technologies based on scanning mode are difficult to realize full-field and real-time detection, and the special experimental environment and requirements in the detection have brought great limitations to the actual measurement. Electronic speckle pattern interferometry (ESPI) shows the advantages of full-field, non-destructive, and real-time detection [9–12]. By combining ESPI and Linnik micro structure, high-precision inspection of microstructure can be achieved [13–15]. Whereas the optical structure of Linnik system is complex, and it is easy to be affected by environmental noise and vibration, which will affect the measurement accuracy.
Characterization of elastic parameters for functionally graded material by a meshfree method combined with the NMS approach
Published in Inverse Problems in Science and Engineering, 2018
Combined with the least squares methods, Cottin et al. [6,7] developed input and modal residuals to identify the parameters in elastomechanical systems. Pagnacco et al. [8] proposed a parameter identification method which is based on the finite element method (FEM) and additional measurements for the displacements and distributed load. With the aid of electronic speckle pattern interferometry measurements and the FEM, the parameter determination on the elastic orthotropic material was implemented [9,10]. Similarly, Li et al. [11] combined the commercial software ABAQUS with the Levenberg–Marquardt (LM) method [12] to propose an inverse parameter identification method for orthotropic composite structures. Recently, Huang et al. [13] combined the isoparametric graded finite element model with the LM method to identify of the material parameters the plane structure of FGMs. All the above-mentioned inverse strategies were based on the FEM solver. An important drawback of the FEM is to maintain the detailed computational mesh, comprising all nodal and element-based connectivity, and hierarchical data. It makes mesh modifications and re-meshing a messy business.