Study On Temperature Sensor With Optical Fiber Thermal Bimetal Sheets Fabry-Perot Cavity

With incessant maturity of the technology and ulterior fall of the development cost, the applications of optical fiber sensor (OFS) have been significantly extended, especially to some particular fields in recent years. In this paper, an optical fiber temperature sensor was studied to provide a kind of simple, feasible, essential safe and reliable temperature detection device that could be applied in flammable and explosive environment.A novel structure of temperature sensor with thermal bimetal sheets, based on optical fiber Fabry-Perot (F-P) cavity was introduced in this paper. The scheme was based upon F-P interference, the F-P cavity was composed with one polished surface of bimetal and one polished end face of optical fiber inserted in a common flange optical fiber connector. When temperature changes, the bimetal sheets confined under the structures designed in the paper will produce a thermal strain and change the F-P cavity length, the intensity output of the sensor will vary, then measuring this changement a temperature sensor could be realized.The F-P structure, especially the thermal-strain mechanism of thermal bimetal sheets were investigated deeply in the paper, the Finite Element Analysis(FEA) results for both the "four nodes" and the "ring" confinements were given; the size of the ring hole can be simply changed to agilely meet the requirement of the different measurement range; the materials match and the parameters selection of the thermal bimetal sheets were analyzed and discussed, and some available suggestions were given; the F-P temperature sensors with the two developed bimetal sheets confinement mechanism were designed and fabricated, the practical measurements were carried out, and the experiment results were analyzed and discussed. The theory analysis and experiment results showed that the optical fiber temperature sensors with the thermal bimetal sheets F-P cavity possess many advantages: simple structure, low cost, practicable usage, and the measurement range can be extended easily.