基于差分探测的低相干外差干涉间隙测量技术  

Low-coherence Heterodyne Interference Clearance Measurement Technology Based on Differential Detection

作　　者：李靖 张伟[1] 邵斌 樊星 章鹏[1] 陈伟民[1] LI Jing;ZHANG Wei;SHAO Bin;FAN Xing;ZHANG Peng;CHEN Weimin(The Key Laboratory for Optoelectronic Technology&Systems of Ministry of Education,College of Optoelectronic Engineering,Chongqing University,Chongqing 400044,China)

机构地区：[1]重庆大学光电工程学院光电技术及系统教育部重点实验室,重庆400044

出　　处：《光子学报》2021年第9期98-106,共9页Acta Photonica Sinica

基　　金：国家自然科学基金(No.51805054);中国博士后科学基金项目(No.2018M643405);中国航发集团创新平台项目(No.SHYS⁃GXDPL⁃18)。

摘　　要：针对低相干外差干涉间隙测量技术应用于发动机、燃气轮机等设备内部高温、高压、强振等恶劣环境时,面临信号弱、信噪比差导致测量范围受限的问题,提出利用差分探测技术来提升拍频信号信噪比的方法。围绕所提出的方法,建立了严格的间隙测量模型,并从理论上说明了其具有提升信号信噪比、扩大测量范围的优势。为证明方法的可行性,搭建了全光纤低相干外差干涉间隙测量实验验证系统,进行单端探测与差分探测的间隙测量对比实验。实验结果表明在同等测量条件下,差分探测方式将信噪比提高了4.22倍,测量范围由10 mm增加到了20 mm。进一步,对系统的测量不确定进行了分析,理论和实验均表明,由于光纤延迟器件扫描速度的不稳定性,系统测量不确定度整体上具有随测量间隙增大而增大的趋势,但在20 mm测量范围内,测量不确定不超过15μm。The clearance measurement environment of engine and gas turbine is harsh due to the high temperature,high pressure,and strong vibration.In such a measurement environment,the low-coherence heterodyne interferometric clearance measurement technique faces the problem of weak signal and the limited measurement range caused by the low Signal-to-Noise Ratio(SNR).To address this problem,a method using differential detection is proposed to enhance the SNR.The theoretical measurement model of the proposed method is strictly established,and the model indicates the method has the advantages of improving the SNR and expanding the measurement range.To prove the feasibility of the method,an allfiber clearance measurement experimental verification system is built,and a comparison experiment between single-ended detection and differential detection is carried out.The experiment result shows that,under the same measurement conditions,the differential detection method improves the SNR by 4.22 times and increases the measurement range from 10 mm to 20 mm.Furthermore,the measurement uncertainty of the system is analyzed.It is theoretically and experimentally found that,due to the scanning speed instability of the optical fiber delay device,the measurement uncertainty increases with the increase of the clearance.But within 20 mm,the measurement uncertainty is less than 15μm.

关 键 词：光学技术与仪器 间隙测量 低相干干涉 外差干涉 差分探测 光纤 发动机 

分 类 号：O436.1[机械工程—光学工程]