基于振动抑制高精度宽带激光扫频干涉测量方法  

A method of suppressing vibration for high precision broadband laser frequency scanning interferometry

作　　者：刘国栋[1] 许新科[1] 刘炳国[1] 陈凤东[1] 胡涛[1] 路程[1] 甘雨[1] 

机构地区：[1]哈尔滨工业大学电气工程及自动化学院,哈尔滨150001

出　　处：《物理学报》2016年第20期272-278,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51275120;61275096)资助的课题~~

摘　　要：本文研究了基于振动抑制的高精度宽带激光扫频干涉测量方法.在激光扫频干涉测量中振动引起目标位移,导致在测量信号拍频中叠加了多普勒频移,该频移量通常远大于目标实际位移产生的频率变化,直接计算目标距离将造成测距精度下降.为解决该问题,本文首先建立了振动对宽带激光扫频干涉测距系统的影响模型,分析了振动对测距的影响机理,通过对测量系统的色散失配效应进行补偿降低了色散影响,然后对测量信号进行交叠分时Chirp Z变换计算不同时刻目标距离,进一步结合卡尔曼滤波方法对目标距离信息进行状态估计,使测量的标准差由185.4μm降低到9.0μm,有效降低了环境振动对测量结果的影响,提高了测量精度.该方法在不需要改变激光扫频干涉绝对距离测量装置的条件下,为进一步提高振动环境中的测距精度提供了解决方法,降低了装置复杂度和成本.In the paper we study the method of reducing environmental influence in broadband laser frequency scanning interferometer. Target displacement caused by vibration will result in Doppler shift in measurement beat frequency.The extent of frequency shift is usually much larger than the actual target displacement. So the direct calculating of the target distance will cause ranging precision to decrease. In this paper, we establish a model for the influence of environmental vibration on the measurement and analyze the influence of the vibration on ranging result. To suppress the vibration effect, the Kalman filter is combined with the overlapping Chirp Z transform to estimate the measured data. The general process is described as follows. Firstly, the tuning nonlinearity will lead to the frequency spectrum broadening, so this paper we use the frequency sampling method to correct the frequency modulation nonlinearity of the laser. The frequency sampling method has the advantages of high speed and high precision. Secondly, the measurement system has the dispersion mismatch effect due to the use of broadband frequency swept laser. To solve this problem,the influence of the dispersion on the measurement is reduced by using the method of dispersion chirp slope calibration.Thirdly, because of the long frequency sweep period of the external cavity swept frequency laser, the vibration process of the target cannot be recorded in real time by single sweep, so in this paper we propose segmenting the measurement signal of single sweep and conducting Chirp Z transform to calculate target distance at different times. Compared with FFT algorithm, Chirp Z transform can achieve arbitrary narrow band spectrum subdivision, with the advantages of high accuracy and fast frequency measurement. Lastly, the Chirp Z ranging result is further combined with the method of Kalman filter to estimate the state of the target distance information. The experimental results indicate that the measurement standard is reduced from 185.4 μm to 9 μm by th

关 键 词：干涉仪 激光频率扫描干涉仪 激光测距 振动 

分 类 号：TH744.3[机械工程—光学工程]