Speckle Photography for Fluid Mechanics Measurements

Study on concurrent measurements of velocity and density distributions for high-speed CO2 flow

“…(1) must be inverted to reconstruct the true density field by the speckle tomography (Fomin, 1998). Since the tomography methods (Gordon, 1974) update the density distributions by using the feedback information of the density itself instead of the density gradient, the ray deflection angle \SP from the digital speckle system should be converted to the interferometric fringe shift \IF which can be expressed as the integration of the density itself (Ko and Kihm, 1999) from the integration of the deflection angle along the perpendicular direction of the light ray s as follows:…”

Limited projections laser speckle tomography of complex flows

“…At the reconstruction stage, the complex interference pattern of the object waves is reconstructed in HI, and the more simple ''standard'' Young's interferometric fringes are reconstructed in SP. The first one is a good means of large structure visualization in a complex flow, whereas the second one is used for a large amount of experimental data accumulation using computer-aided optical data acquisition systems, with the aim of subsequent statistical flowfield analysis and turbulence parameters determination, see [12].…”

“…Different types of tomographic techniques have been developed for the reconstruction of 3D flow structures [5][6][7][8]. Among them speckle technique looks as one of the most promising [9][10][11][12]. The present paper discusses two mathematical procedures of 3D flow field reconstruction based on classical Radon integral transform and on a novel Erbeck-Merzkirch integral transform connected with statistical speckle data treatment and numerical flowfield simulation.…”

Quasi-real time bio—Tissues monitoring using dynamic laser speckle photography

“…Thus, the evolution of the dynamic bio-speckle pattern has more complicated character as compared with PIV technique, where the particle image displacement is always directly proportional to the particle displacement in the flow studied (Kompenhans et al, 1998, Fomin, 1998a. The experimental arrangement used in this study is shown in Fig.…”