Displacement and acceleration measurements in vibration tests using a fiber optic sensor

This paper discusses the evaluation of displacements and accelerations from noncontact displacement measurements using a low-cost plastic fiber-optic sensor. Issues about sensor calibration in the presence of nonuniform targets, which is a situation occurring in many practical applications such as vibration tests of printed circuit board assemblies, are analyzed. Furthermore, a procedure to contemporaneously calibrate several optical sensors to allow mapping the vibration amplitude and acceleration distributions in a simple and low-cost way is also disclosed. The proposed calibration procedure is particularly effective since it requires just one reference accelerometer, which is actually already available in typical vibration test facilities. Experimental results obtained under real conditions during a sinusoidal vibration test are also provide

A Fiber Optical Sensor For Non–Contact Vibration Measurements

This paper describes an intensity based optical sensor for the evaluation of accelerations from non-contact displacement measurements. Plastic optical fibers are used to collect the reflected light from several points on the vibrating surface, allowing the reconstruction of the vibration distribution. Two compensation techniques to reduce systematic effects due to the target reflectivity are also described and compared: one is based on the spectral analysis of the received optical signal and the other takes advantage of a reference displacement sensor. Experimental results in real conditions during vibration tests have demonstrated the capability to measure sub-micrometer vibration amplitudes up to about 40 kHz

Issues concerning intensity-based fiber sensors for non-contact vibration monitoring

The paper describes a simple fiber optic sensor for non-contact vibration measurements. The sensor is based on a couple of optical fibers placed in front of a vibrating target and derives the vibration amplitude from the changes of the reflected light intensity. A model of the optical sensor is introduced to predict the sensor behavior in different working conditions and for different sensor configurations. Then, issues concerning the sensor calibration in the presence of arbitrary targets, the choice of the sensor working distance, the strategies for sensitivity enhancement and the noise effects are investigated

Optical fiber sensors for long- and short-term crack monitoring

This paper describes a fiber displacement sensor and analyzes its performance in evaluating the evolution of cracks for structural health monitoring applications, both over short and long time periods. The sensor is based on plastic optical fibers, a choice that allows having all the advantages typical of optical fibers, but with costs comparable to the more common electro-mechanical systems. Two sensor topologies have been realized and some experimental results about laboratory and in field tests are reported to assess the effectiveness of the proposed solutio

POF sensor network for monitoring the Guarini Chaper

The application of a permanent monitoring system architecture built on nodes composed of intensiometric POF sensors connected to a battery-operated, radio-controlled, interrogation units is presented. The paper describes the realization of the mixed radio-POF sensor network and discusses the results obtained during the first months of operation, highlighting the criticalities due to parasitic influences. The obtained results show that the proposed monitoring architecture is well suited for applications in historical buildings where fire-safety is of primary concern