Research Of A DSP-based High-resolution Fiber Bragg Grating Sensor Interrogation System

As a new type of sensor, Fiber Bragg Grating (FBG) has many advantages, whichhas been used in many fields like petrochemical industry, civil engineering, Aerospace,medical electronics and so on. However, a complete fiber grating sensing system notonly includes the module of sensing, but also should have the interrogation module. Thecurrent interrogation systems have many problems like high price, large volume, lowaccuracy of interrogation and so on. In this paper, we design a DSP-based highresolution FBG sensor interrogation system according to the current research situationof FBG sensing system. This system will realize high resolution, high sensitivity,miniaturization and Practical of the interrogation system.Firstly, the DSP-based high-resolution FBG sensor interrogation system we havedesigned includes three parts: high precision tunable laser source module, sensingmodule and high precision DSP interrogation module. The high precision tunable lasersource module is a fiber optical laser based on Fiber Fabry-Perot filter (FFP). In order torealize the high precision and tuning of the optical soure, we use DSP and a20bitsprecision of D/A conversion module to realize high precision modulation voltage whichis used to control the FFP. We use FBG as our sensing module, which has a Centerwavelength of1549.8888nm,3dB bandwidth is0.165nm and the reflectiv is98.34%.The interrogation system realized as below, we use the sinusoidal modulation laser toscan the transmission spectrum of FBG, and then convert the light information intoanalog voltage signal. The DSP module converts the analog voltage signal into digitalsequences which include the sensing information. After the processing of DSP-basedlock-in amplifier system, we can get the sensing information.Secondly, In order to validate the feasibility of the DSP_based interrogation system,we do some simulations to test the Lock_in amplifier interrogation algorithm. Then wedesign two interrogation systems based on Agilent: HP8164A tunable laser and S830Lock_in amplifier and compare the result with the interrogation system designed in thisarticle. In the end of this article, we use mathematical methods like least square method,related algorithm and so on to process the experimental data. The result shows that wecan get the sensoring information from the interrogation datas effectively through themathematical methods.The research in this article shows that the DSP-based high-resolution fiber Bragggrating sensor interrogation system is feasible. It has the characters of low price, highsensitivity, tiny, reliability and easy to use in engineering.