Imaging system considerations in Doppler global velocimetry

Helen D. Ford; Ralph P. Tatam

doi:10.1117/12.221550

29 September 1995 Imaging system considerations in Doppler global velocimetry

Helen D. Ford, Ralph P. Tatam

Proceedings Volume 2546, Optical Techniques in Fluid, Thermal, and Combustion Flow; (1995) https://doi.org/10.1117/12.221550
Event: SPIE's 1995 International Symposium on Optical Science, Engineering, and Instrumentation, 1995, San Diego, CA, United States

Abstract

Doppler Global Velocimetry (DGV) is a full-field optical technique for the measurement of fluid flow velocities. The flow is illuminated using a light sheet, and the Doppler shift imposed on light scattered from moving particles within the sheet is imaged through a cell containing iodine vapor onto a solid-state array camera, thereby converting the Doppler frequency shifts into intensity variations in the image. In this paper, a DGV system is presented based around an argon-ion laser source and a fast digital image-processing system, which allows the DGV velocity map to be updated at camera frame rate. Interpretation of DGV images is complicated by errors which arise at positions some way out in the field of view due to the modified illumination and viewing vectors corresponding to these positions. Typical magnitudes of such errors are calculated. Significant errors can arise for points more than about 5 degree(s) out from the center of the field of view, and for divergence angles of the illumination beam exceeding about 10 degree(s) at a distance of 5 cm from the beam axis. Other considerations affecting system accuracy are also discussed.

Citation Download Citation

Helen D. Ford and Ralph P. Tatam "Imaging system considerations in Doppler global velocimetry", Proc. SPIE 2546, Optical Techniques in Fluid, Thermal, and Combustion Flow, (29 September 1995); https://doi.org/10.1117/12.221550

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