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Optical Engineering

Evaluation of the two-fiber laser Doppler anemometer for in vivo blood flow measurements: experimental and flow simulation results
Author(s): Chuan Swee Tjin; David Kilpatrick; Peter R. Johnston
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Paper Abstract

A two-fiber laser Doppler anemometer was built and tested with the fiber probe placed parallel to the flow. Nine combinations of fiber diameters and fiber separations were tested, and the dominant and maximum shift frequencies were plotted as a function of the unperturbed (or freestream) flow velocity. For both the forward (toward the fiber tip) and reverse (away from the fiber tip) flow directions, the graph of the flow velocity against the maximum shift frequency shows better linearity and approaches closer to the theoretical line than the graph of the flow yelocity against the dominant shift frequency. For the forward flow, the Doppler frequency is close to that predicted and linear above 20 cm/s, but for the reverse flow the slope is only one-quarter of that predicted. Analysis of the data showed that the region of flow perturbation decreases towards the fiber tips in the forward flow, whereas it extends away from the fiber tips in the reverse flow. In its present form, the two-fiber system cannot then be used for accurate blood velocity measurements, since linear calibration between the forward and reverse flow velocities cannot be achieved.

Paper Details

Date Published: 1 February 1995
PDF: 10 pages
Opt. Eng. 34(2) doi: 10.1117/12.194040
Published in: Optical Engineering Volume 34, Issue 2
Show Author Affiliations
Chuan Swee Tjin, Nanyang Technological Univ. (Singapore)
David Kilpatrick, Univ. of Tasmania (Australia)
Peter R. Johnston, Univ. of Tasmania (Australia)


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