基于电控光学采样的飞秒激光距离测量系统  

Femtosecond Laser Distance Measurement Based on Electronically Controlled Optical Sampling

作　　者：薛睿 武子铃 董佳琦 胡明列[1] 宋有建[1] Xue Rui;Wu Ziling;Dong Jiaqi;Hu Minglie;Song Youjian(Key Laboratory of Optoelectronic Information Technology Science,Ministry of Education,School of Precision Instrument and OptoElectronics Engineering,Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学精密仪器与光电子工程学院光电信息技术科学教育部重点实验室,天津300072

出　　处：《光学学报》2023年第3期78-85,共8页Acta Optica Sinica

基　　金：国家自然科学基金(61827821);广东省重点领域研发计划(2018B090944001)。

摘　　要：基于电控光学采样原理开展了飞秒激光飞行时间绝对距离测量的实验研究。电控光学采样技术使用两台重复频率锁相的飞秒激光器,分别作为信号激光器和本地振荡器。在本地振荡器的谐振腔内插入电光调制器并施加方波调制,实现了可控、高效的等效时间采样,采样速度由电光调制器的调制频率决定。基于这一采样原理开展脉冲飞行时间绝对距离测量实验。选用一对重复频率约为158 MHz的被动锁模光纤激光器作为光源,对固定目标进行单次测量的最大更新速率可达到200 kHz,经过4100次单次测量平均后,测距精度可达到16.7 nm。在此基础上,测量了硅基微机械器件中深度约为67.6µm的微槽。Objective Timeofflight distance measurement based on a dualcomb approach is widely applied in the fields of laser radar,topography scanning,and vibration measurement by using two femtosecond lasers with a small repetition frequency difference for asynchronous optical sampling(ASOPS).In this manner,the high temporal resolution,combshaped spectrum,and ultralow noise performance of femtosecond lasers can be fully utilized.However,the update rate of a dualcomb ranging system based on ASOPS is limited to a few kilohertz(determined by the repetition frequency difference)so as to avoid insufficient optical sampling.Given the extremely small duty cycle determined by the ratio of the femtosecond pulse width to the millisecond sampling period,most of the sampling time during a full sampling cycle is wasted in the process of pulse walkoff.To solve this problem,an electrooptical modulator(EOM)is added to the ASOPS system to modulate the repetition frequency periodically in this work.The socalled electronically controlled optical sampling(ECOPS)approach breaks the update rate limitation in the ASOPS system and can increase the update rate to hundreds of kilohertz,further enriching the application fields of dualcomb distance measurement technology.Methods ECOPS uses two lasers with tightly phaselocked repetition frequency(fr)as the light source.One is called a local laser with an EOM inserted in the cavity,and the other is called a signal laser.The EOM in the cavity is used to modulate the repetition frequency of the local laser.As a square wave is imposed on the EOM,the repetition frequency is switched between fr−Δfr and fr+Δfr,and the modulation period is determined by the square wave modulation frequency fm.Therefore,the repetition frequency difference between the two lasers switches between-Δfr andΔfr at the modulation frequency fm.Different from ASOPS with only a fixedΔfr,the rapid switching of±Δfr effectively drives the output pulse of the local laser to scan back and forth on both sides of the output pulse of t

关 键 词：测量 飞秒脉冲 电控光学采样 飞行时间 绝对距离测量 

分 类 号：TN249[电子电信—物理电子学]