Multicomponent frequency shifting self-aligning laser velocimeters

A design using simple lenses and frequency shift by scattering disk has been developed, which allows easy construction, and alignment of one-, two-, and three-orthogonal-component, frequency shifting laser Doppler velocimeters. A series of instruments designed on this basis have proved to be inexpensive to construct, precise and accurate to use, adaptable to a wide range of applications, and have proven particularly advantageous in studies of turbulent phenomena and complex flows. In this paper the design concept is explained, construction and alignment procedures are outlined for the simplest assembly of the one and two component versions, and performance and application examples are presented. The extension of the system to measure the third orthogonal component is discussed.