光学低相干干涉频域信号的探测和分析

Detection and analysis of optical low coherent interference frequency domain signals

采用宽带LED白光光源,搭建了基于迈克耳孙干涉仪结构的低相干干涉测量实验平台.利用光纤光谱仪采集不同光程差下的光谱信号,分析并测量了光谱探测的工作距离范围,提出了采用衍射光栅对光谱信号进行色散并直接成像的方法.实验结果显示:系统最大光谱工作距离为100μm量级,远大于光源相干长度,即使光程差在相干长度范围以外,无法直接观察到干涉条纹,也能通过光谱信号的周期调制特性来快速搜寻白光干涉信号,简化了干涉仪的调试过程.

An optical low-coherent interference experimental system based on Michelson interferometer was designed and built by using a broadband LED white light source.The spectral signals under a series of optical path differences were collected by an optical fiber spectrometer and the working range of spectral detection was analyzed and measured.A method using diffraction grating to disperse and directly image the spectral signal was proposed.Experiment results showed that the maximum spectral working distance was on the order of hundreds of microns,much larger than the coherence length of the light source.Even if the optical path difference was over the range of the coherence length where the interference pattern could not be observed,the white light interference signal could be quickly found through the periodic modulation characteristics of the spectra,which simplified the application of the interferometer.