1 June 1988 Velocity Field Visualization Using The Doppler-Picture Technique
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Proceedings Volume 0863, Industrial Optoelectronic Measurement Systems Using Coherent Light; (1988) https://doi.org/10.1117/12.943482
Event: 1987 Symposium on the Technologies for Optoelectronics, 1987, Cannes, France
A novel technique for visualizing and measuring an entire velocity field with only one photograph has been developed by taking "Doppler-pictures" with a Michelson interferometer. The Doppler-picture gives information, either about the instantaneous velocity distribution of a fast moving and/or deforming solid reflecting surface, or about the instantaneous and local velocities of tracers passing through a light sheet that cuts the flow field under investigation. The light sheet is produced by a widened laser beam. The Doppler-shift of the frequencies of the light scattered by the tracers is transformed by a Michelson interferometer into varying light intensities, thereby shifting a given initial interference fringe pattern. Generally, the interference fringes are adjusted to a constant frequency of the scattered light, which must be straight, parallel and equi-distant. The light intensities also depend on the intensity of the scattered light, but this occurs only in the illuminated fringe regions. The dark fringe areas with no light remain practically uninfluenced by the varying intensities of the scattered light. That is why, it is only the dark fringes that can be used for determining the measured velocity field distribution in the evaluation of Doppler-pictures. The tracer velocities along the dark fringes can be obtained by simply measuring and comparing the shift of the dark fringes with the initial fringe pattern. This new visualization method will be described in principle, and the use of our Doppler-picture camera will be demonstrated with Doppler-pictures of (a) circular supersonic free air jets coming out of a Laval-nozzle, (b) a cutting torch outflow, (c) vortices, (d) moving shock waves showing the velocity rise across it and (e) a fast rotating solid drum.
© (1988) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
J. Srulijes, J. Srulijes, F. Seiler, F. Seiler, A. George, A. George, } "Velocity Field Visualization Using The Doppler-Picture Technique", Proc. SPIE 0863, Industrial Optoelectronic Measurement Systems Using Coherent Light, (1 June 1988); doi: 10.1117/12.943482; https://doi.org/10.1117/12.943482


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