Practicable fiber optic displacement sensor with subnanometer resolution

Abstract

A practicable fiber optic displacement sensor with subnanometre resolution is described . It consists of a He-Ne laser source , a directional fiber coupler as a beam splitter , a probe made up of optical fibers and a photodetector setup . Its principle is based on the highly sensitive detection of power change at a " zero " working point in light reflected from an object surface to be measured when the surface is subject to a small displacement . In operation , the probe of sensor carries the incident light to the object surface and receives the reflected light . The probe divides the reflected light into two signals . The two light signals are then transmitted to two photodetectors through the optical fibers . By employing a differential amplifier , we can acquire a highly sensitive displacement signal at the " zero " working point . The result of measurement is not sensitive to the power fluctuation of the light source . The measurement is noncontact . The working range is about 6Oum . The probe is small with diametre less than 5mm . It is also easy for the sensor to be used to measure pressure , strain , vibration , etc

Fast low-cost fiber-optic displacement sensor

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Fast four-channel fibre-optic displacement sensor for measuring impact waves at low cost

“…Using optical fibres for such applications is not a new idea [8][9][10][11][12]. This paper, expanding on the work presented at OFS-17 [13], outlines how a simple yet effective and reliable fibre sensor was built at small cost.…”