Laser Doppler velocimeter with a novel optical fiber probe

Continual mechanical vibration trajectory tracking based on electro-optical heterodyne interferometry

Vibration is one of the confused problems in many fields. To give a comprehensive analysis of vibration, an electro-optical heterodyne interferometry with temporal intensity analysis method that can track the trajectory of the vibration dynamically has been built in this paper. The carrier frequency is introduced by the electrically controlled electro-optical frequency shifter. The trajectory is obtained by using temporal evolution of the light intensity in heterodyne interferometry. The instantaneous displacement of the vibration is extracted with spectral analysis technique. No target mirror and moving parts are required in our self-developed system. The principle and system configuration are described. The simulations and the preliminary experiments have been performed and the results show that this trajectory tracking system is high-efficiency, low-cost, jamproof, robust, precise and simple.

Fiber optic vibration sensor for remote monitoring in high power electric machines

A novel fiber optic vibration sensor is presented, based on the motion detection of an elastic cantilever by means of the optical triangulation technique. The sensor was designed to work at a fixed frequency of 100 Hz for applications in high power electrical plants where insulation and EM immunity requirements make fiber optic sensing the most suitable choice. The working linear range reaches a peak amplitude of 0.25 mm; resolution is 0.1 microm; accuracy is better than +/-3%; and sensitivity is 10 mV/microm. Design details and experimental results are reported.

Fiber-optic measurement of the deformation field on a remote surface using numerically processed white-light speckle

Fiber optics provides a means of making optical measurements on remote or otherwise inaccessible surfaces by transmitting reflected light from that remote surface to an appropriate place and/or system for recording and analysis. In this study fields of artificially generated random speckle on the surface of a deformable test subject are transmitted at various magnifications through a coherent multimode fiber optic bundle (MMB) to a vidicon camera-digitizer system (VCD) where they are recorded for successive states of surface deformation. These results are then numerically correlated to provide a measure of that surface deformation at a number of different locations for each pair of recorded speckle fields.

Image velocity sensing using an optical fiber array

A noncontact velocity sensor with an optical fiber array is described. The end faces of optical fibers which are linearly arrayed at equal intervals act as the spatial filter for velocity sensing. The characteristics of this sensor are investigated in terms of the number of optical fibers, the fiber interval, and the object spectrum. The usefulness of this sensor is confirmed by calculations of the selectivity and experiments. Furthermore, it is shown that an imaging system with a cylindrical lens is effective for measuring the velocity of an object with a large sideway motion.