The Realization And Application Of Multi-channel Flrds Sensor

Fiber-Loop Ring-down Spectroscopy (FLRDS) is a novel technology, which demonstrates great advantage in measurement of tiny changes of several parameters, such as pressure, strain, concentration. Recently, a duel-channel FLRDS system has developed. Based on the principle time-division multiplexing, this idea suggests a new trend for FLRDS with more channels.This paper first describes a four-channel fiber-loop ring-down sensor with temperature compensation based on neural networks. We tested its feasibility by giving an example of four-channel pressure sensor. This fiber ring-down pressure sensor makes use of the principle of time division multiplexing, which consists of series and parallel fiber loops. The laser pulses from four channels can be acquired by only one detector and the four pressure values are measured synchronously. The experimental result has testified the feasibility of four-channel ring-down pressure sensor. In that case that multi-channel measurement is needed, this sensor reduces the cost.Taking mode dispersion in multimode fiber into consideration, the maximum multiplexing number is discussed. The maximum multiplexing number increases as the length of fiber loop goes up while decreases with the growth of the initial width of laser pulse and circulation times.In addition, environmental temperature can create a disturbance to the test result of sensor. For example, our experiment showed that in the process of measuring pressure, the pressure sensor is easily affected by the change of temperature. In order to eliminate the disturbance of environmental temperature, temperature compensation based on neural networks has been successfully used in our experiment.Last but not least, we come up with a design of current sensor based on giant magnetostriction effect. In theory, it is able to detect three phase current simultaneously in electrical industry.