Design and performance of a heterodyne all‐fiber laser Doppler velocimeter

Design Considerations for a 3d Fibre Optic Laser Doppler Velocimeter for Turbomachinery Applications

Single headed 3D Laser Doppler Velocimetry (LDV) geometries generally rely upon the use of 3 Doppler difference channels, inclined at differing angles with respect to the mechanical axes of the probe. The transformation between the non-orthogonal measurement co-ordinate system and the Cartesian system can result in large errors in the calculated velocities. A theoretical analysis of the geometr...

Heterodyne laser tracking at high Doppler rates

A design is described for a transmitter/receiver system that may be used in a spaceborne laser heterodyne tracking system to produce a high-precision interferometer. We present a two-color laser scheme that enables accurate phase measurement even in the presence of a large Doppler offset between the incoming and outgoing signals. The beat note between the two lasers provides a built-in frequenc...

Directional spatial-resolved laser Doppler velocimeter using a two-colour fibre laser

A concept for the realisation of directional laser Doppler velocimeters (LDV), without having to use opto-electronic modulators like Bragg cells is presented. The concept is based on the use of a diode-pumped fibre laser, emitting at two different wavelengths. The two laser colours are used to generate two interference fringe systems in the measuring volume of the LDV system. The fringe systems...

An Experimental Investigation of Vortex Rings and Helicopter Rotor Wakes Using a Laser Doppler Velocimeter

Measurement of Reynolds Stress Distribution in a Fluidic Element by the Laser Doppler Velocimeter

The one-phase flow and the two-phase flow in a fluidic element are investigated by measuring Reynolds stress distributions of the main jets using the laser Doppler velocimeter. In the one-phase flow, a water flow jets from a main nozzle into water and in the two-phase flow, a water fiow jets into air. Some results with the one-phase flow are as follows. When either of the two control ports is c...