Coherent Sensors For Hostile Environments

James P. Waters

doi:10.1117/12.947667

14 December 1988 Coherent Sensors For Hostile Environments

James P. Waters

Proceedings Volume 0955, Industrial Laser Interferometry II; (1988) https://doi.org/10.1117/12.947667
Event: SPIE International Symposium on Optical Engineering and Industrial Sensing for Advance Manufacturing Technologies, 1988, Dearborn, MI, United States

Abstract

Interferometric measurements in high vibration environments or in a turbulent medium can be impossible because of alignment problems and induced phase noise on the signal. Significant improvements to interferometric sensors have been realized with the use of a semiconductor laser as the light source and by enclosing the beam paths in optical fibers. These two advances make the transducer more flexible while improving reliability. Problems unique to fiber-optic interferometers have also been solved resulting in a rugged instrumentation package for measuring localized vibrations in manufacturing environments. In all of these techniques, however, the beam leaves the fiber to probe the surface of the object and is subsequently collected by a lens for return via the fiber. During this process, most of the light is lost, drastically reducing the signal-to-noise ratio. Also, while outside of the fiber, the phase of the beam can be perturbed by index variations in the surrounding medium. These perturbations can destroy the signal in applications where measurements are made on surfaces at elevated temperatures or on objects located in a turbulent medium. A new design for an interferometric sensor has been devised and implemented in a remote bearing vibration monitor where the light does not leave the fiber. In this particular application, the sensor and bearing are in a highly turbulent medium and are located over 100 meters from the laser light source and processing electronics. The design of this transducer and preliminary test results will be presented.

Citation Download Citation

James P. Waters "Coherent Sensors For Hostile Environments", Proc. SPIE 0955, Industrial Laser Interferometry II, (14 December 1988); https://doi.org/10.1117/12.947667

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