【作者】 何萌；

【导师】 江俊峰；

【作者基本信息】 天津大学 ， 光学工程， 2009， 硕士

【摘要】 光纤Bragg光栅传感器对待测量采用波长编码,对光强的波动及光的偏振态不敏感,抗干扰能力强,测量方便,因此光纤光栅在传感方面的应用得到了国内外的广泛关注。目前已推出商用光纤光栅解调产品,但主要以有源解调方法为主,采样速度在几赫兹到几百赫兹左右,仅能满足静态或准静态测量的需要,不能满足振动、地质监测等动态环境所要求的高速采样。为了进一步满足动态测量的要求,需提高光纤光栅解调仪的采样和传输速度。本课题针对这一要求,设计了基于CPLD总线控制和边缘滤波器的高速光纤Bragg光栅解调仪。完成了解调仪的光路及电路设计,实现了光纤光栅解调系统的解调数据的高速传输及在计算机平台上的处理、显示和存储。本论文的主要工作如下:1、基于粗波分复用器(CWDM)设计了光路解调部分,利用可调谐激光器对CWDM进行测试,测得其可用工作区间为1535.4nm-1542nm,响应灵敏度可达15dB/nm,保证了解调系统的快响应速度和高分辨率。2、以CPLD作为时序主控芯片,研制了控制总线传输的高速光栅解调仪的数据采集与USB传输硬件,包括AD采样以及USB接口控制部分。3、使用Verilog语言设计完成了CPLD的主控程序,利用模块式编程方式完成了对同步传输对系统时钟的设计要求,实现了对整个解调电路及接口传输的时序控制,保障了数据的高速无重复传输。4、完成了EZ-USB2.0接口芯片的固件驱动程序设计,经过对比研究,设计了同步批量半满传输的固件程序,通过对USB芯片的传输模式及控制命令的设计,实现了USB接口高速无重复传输数据。5、建立实验系统,对解调系统的采样速度、传输性能、解调范围和波长分辨率进行了实验分析与研究。实验结果表明该解调系统的采样速度为240KHz,可解调20KHz以下的动态信号;深入研究了三种典型的光输入功率下对解调范围的影响,光功率大于或等于-14dbm时,解调范围为1535.4nm-1542nm;分辨率达到了18pm。更多还原

【Abstract】 The measurement signal of Fiber Bragg Grating Sensors is wavelength encoded, is not sensitive to the intensity and the state of polarization,and has powerful anti-disturbing capability, that is why the application of the fiber Bragg grating in sensor field has been widespread concern at home and abroad. There are some demodulation products for fiber grating sensors, which are mostly based on passive demodulation technologies, and the samling rate is between several hertz to several hundred hertz or so, can only meet the needs of static or quasi-static measurement, but is not enough to achieve the geological monitoring in dynamic environment. In order to adapt the requirement of dynamic measurement, increasing the sampling and transmission speed of the fiber grating demodulation is needed. As a result, the design of the High Speed Fiber Bragg Grating Demodulation based on CPLD and the Thin Flim Filter technologies is proposed in this papper. The design of optical path and circuit board is completed in this papper; achieve the high-speed transmission of fiber grating demodulation, the date processing, display and store on computer.1、The demodulation for wavelength code in optical path is designed based on Coarse Wavelength Division Multiplexing (CWDW). The performance test on CWDM is done, the experiment result shows that the effective interval is from 1535.4nm to 1542nm, and the sensitivity is arrived at 15dB/nm, which makes the response speed and wavelength differentiating rate high.2、The Complex Programmable Logic Devic (CPLD) is used as the main chip in the design of the acquisition and data transmission hardware system for the high speed FBG demodulation, including the hardware circuit of the A/D chip and the interface control circuit of USB in the project.3、The main control procedure is completed based on Verilog, and the clock of synchronous transmission is finished by Module Programming, which achieves the timing control for the demodulation circuit and the interface, and keeps the data transmitted with non-repetitive on high-speed.4、The firmware program of USB interface chip CY7C68013 is designed; the design of half-full bulk transmission for firmware programming is done by contrast. The data is transmitted with non-repetitive on high-speed through the control command design on the USB chip.5、The experiment system is build, to analyze and research sampling rate, transmission performance, wavelength range and resolution of the demodulation. The experiment results show that the samling rate is 240 KHz, and dynamic signals on 20 KHz can be de-emphasised well. What is more, the impact of demodulation under three typical input opt-power is researched, the demodulation range is from 1535.4nm~1542nm, the resolution is 18pm when the input power is greater than -14dBm.更多还原