Recent developments in fiber optic and laser sensors for flow, surface vibration, rotation, and velocity measurements

Abstract

This paper reviews the theory, implementation, and broad application base of the following fiber optic and laser based non-intrusive sensing and measurement techniques: (1) FiberFlow Laser Doppler Anemometer, for accurate measurements of turbulent flow velocity with high resolution; (2) Modular Vibrometer; (3) Fiber Vibrometer, for measurements of vibrations of surfaces with wide amplitude and frequency ranges; (4) Torsional Vibrometer, for measurement of angular velocity and vibrations of rotating shafts; and (5) Surface Velocity Sensor, for high accuracy surface velocity and length measurements. The first four techniques are based on measurement of the Doppler shift of light scattered from the moving particles or surfaces through interferometric principles (optical heterodyning). Frequency shifting using Bragg cell enables measurements of motions that change direction. The last technique is based on calculation of the transit time of a surface through two spots of known distance, aligned along the direction of motion, through a correlation principle.© (1991) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.