Modeling and Optimization of Magnetic Circuits of a Fiber-Optic Displacement Sensor

The paper is devoted to design optimization of contactless fiber-optic displacement sensors based on the magneto-optical Faraday effect that can be used to monitor the status of plate valves controlling flows of fire and explosion hazardous substances. Design optimization of sensors allows significant improvement of metrological characteristics of measuring systems on their basis. However, issues of design optimization of such sensors have not yet been considered in scientific literature. The paper deals with the design of the valve position sensor, discusses methods of optimizing the sensor design elements and presents the results of solving optimization problems. It is established that design optimization of a magnetic field concentrator makes it possible to increase the optical flux of the sensor element by 34.4%, whereas optimizing the place of installation of a magneto-optical element (MOE) (16 ... 19 mm from the point of inserting optical radiation into optical fiber) allows more than a 7-fold increase of the optical flux. Optimization of the gap between the FOSF and the movable magnetic core mounted on the valve plate allows determining the zone of optimal location of the movable magnetic core on the basis of the permissible change in the FOSF transformation function (the dependence of the FOSF output signal on the position of the valve plate).