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Prism Design and Applications
Published in Paul Yoder, Daniel Vukobratovich, Opto-Mechanical Systems Design, 2017
A wedge prism located in a converging beam will deviate the beam so that the image is displaced laterally by an amount proportional to both the wedge deviation (in radians) and the distance from the wedge to the image plane (see Figure 7.52 for a schematic of the device). If the prism is moved axially by D2 – D1, the image displacement varies from D1δ to D2δ.
Wigner–Ville distribution based diffraction phase microscopy for non-destructive testing
Published in Journal of Modern Optics, 2019
Ankur Vishnoi, Ajithaprasad Sreeprasad, Gannavarpu Rajshekhar
Optical interferometric techniques such as electronic speckle pattern interferometry (1, 2), shearography (3) and digital holographic interferometry (4) have been extensively used for non-destructive metrology in diverse areas such as experimental mechanics, material science, biomechanics and precision engineering. These techniques operate by encoding the measurand information in a fringe pattern, and require a fringe demodulation or analysis (5) method to retrieve the desired information. An important problem in this domain is reliable extraction of phase derivatives from a fringe pattern, which has several practical applications. In electronic speckle pattern interferometry, phase derivatives have been applied for measuring slopes (6) and strain (7, 8), and for dynamic deformation analysis (9). Similarly, there are several applications of digital holographic interferometry involving the use of phase derivatives such as strain, curvature and twist measurements (10–12) and defect identification (13, 14). Compared to the aforementioned techniques, shearography is an optical technique where the influence of the spatial derivative is significantly evident since the experimental setup is designed such that the resulting fringe pattern directly maps the derivative information due to the interference of the wave scattered from the test specimen and its sheared or spatially shifted counterpart generated by a shearing element such as wedge prism (15). Additionally, shearography eliminates the need for a separate reference arm for interference, and is resistant to vibrations. These elegant properties have enabled widespread use of shearography for non-destructive evaluation (15), material characterization (16), leak detection (17) and residual stress analysis (18). However, fringe processing accuracy in shearography is strongly affected by the presence of shearing introduced in the experimental setup and the performance is also sensitive to noise.
Multidimensional Hydraulic Solver Using Structured and Unstructured Meshes for the System Thermal-Hydraulic Code SPACE
Published in Nuclear Technology, 2019
Chan Eok Park, Jong Ho Choi, Gyu Cheon Lee, Sang Yong Lee
In the SPACE unstructured/collocated mesh system, a general polyhedron is used as a basis element, and various types of unstructured mesh are allowed to be used. In three dimensions, the available mesh types include hexahedron, tetrahedron, pyramid, or wedge (prism) shapes of cells, as shown in Fig. 4.