Nonmechanical cross-sectional scanning laser Doppler velocimeter with directional discrimination of transverse velocity component

Abstract

We propose a nonmechanical cross-sectional scanning laser Doppler velocimeter (LDV) with directional discrimination of the transverse velocity component. In the proposed LDV, a combination of changes in wavelength and the port of the fiber array between the main body and probe are used to scan the measurement position on a two-dimensional (2-D) cross-sectional plane that is perpendicular to the direction of flow. Optical frequency shifting using acousto-optic modulators (AOMs) is employed to discriminate the direction of the transverse velocity component. Polarization multiplexing is used to transmit frequency-shifted beams from the main body to the probe. The experimental results reveal that the 2-D scanning function and introduction of directional sensitivity are successfully achieved.