Compensation for refractive-index variations in laser Doppler anemometry.

Techniques to compensate for index of refraction variations in the application of a laser Doppler anemometer are examined. For discontinuous plane-layered media a method of discrete elements is employed. An alternative set of equations is derived for continuous cylindrically layered media and simplified to make comparisons with available results for a single cylinder. Results of velocity measurements in a Plexiglas model of a cylindrically layered nuclear fuel assembly are presented to establish a positioning accuracy of the method to within 0.025 cm.