摘要
太赫兹时域光谱技术在无损检测领域有很好的技术优势和应用前景,提高系统的检测速度和探测频谱分辨率是当前时域光谱技术的一个重要课题,而太赫兹时域光谱系统的检测速度和延迟时间是由光学延迟线决定的。基于透射式太赫兹时域光谱系统,设计了一种新型的旋转式光学延迟线,该旋转延迟线包含24片平面反射镜,通过旋转改变光程,进而产生可变的延迟时间。对该光学延迟线建立了数学模型,并进行了工作状态下光路的仿真与实际实验验证。仿真与实验结果表明,延迟时间可达72ps,扫描频率为60Hz,最小二乘法计算得到的线性度可达99.96%。利用有限元分析(FEA)软件对该延迟线的机械结构进行了旋转状态下的受力分析和模态分析,验证了该设计在工作中的可靠性与稳定性。该设计相比现有的太赫兹时域系统中的线性延迟线,有更快的扫描速度和更长的线性延迟时间,有利于太赫兹时域光谱系统的光纤集成化。
Objective The terahertz time-domain spectroscopy(THz-TDS)technology has superior technical advantages and application prospects in the field of non-destructive testing.Improving detection speed and detection spectral resolution is an important topic of current time-domain spectroscopy technologies.The detection speed and the delay time of a terahertz time-domain spectroscopy system are determined by the optical delay line.The laser in the THz-TDS system is a femtosecond pulse,but the response time of the detector is about sub-nanosecond.By modifying the time delay between pulses,the repeating signal generated by the high frequency femtosecond pulse is converted to a low frequency signal for processing,so that the detector can sample the repeating signals for multiple times to realize equivalent sampling.In this paper,a high-speed linear optical delay line,used in optical coherence tomograph(OCT),is designed for a fiber THz-TDS system.The analysis of delay line is carried out for optical simulation,error analysis,and test experiments,and the quality and working stability of the exit beam are measured.Methods A fast rotation optical delay line(FRODL)is made of aluminum alloy.Its mathematical model consists of a base circle and a mirror array with 24plane mirrors,and the laser is incident to the center of the mirror along the center of the base circle.After reflection from the mirror,it enters into the collimating focusing mirror and is coupled into the optical fiber.When the rotating delay line is working,a horizontal distance change and a vertical distance change are generated on the mirror.So,the optical path change can be described by these variables.First,the influence of different variables on delay time is analyzed by a mathematical analysis software,and the linearity of delay time is calculated.Second,the optical simulation software LightTools is used to simulate the laser path and the beam quality under different angles of working situation.In the simulation,the laser wavelength is 635nm and the beam diamet
作者
辛胤杰
李全勇
程爽
蒋锐
王奇书
Xin Yinjie;Li Quanyong;Cheng Shuang;Jiang Rui;Wang Qishu(Key Laboratory of Optical Control and Optical hiformaticm Transmission Technology of Ministry of Education,College of Opto-Electronic Engineering,Changchun University of Science and Technology,Changchun,Jil'm 130022,China;National Demonstration Center for Experimental Opto-Electronic Engineering Educatiori,College of Opto-Electronic Engineering,Changchun University of Science and Technology,Changchun,Jilin 130022,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2022年第6期169-177,共9页
Chinese Journal of Lasers
基金
吉林省科技资源开放共享服务平台与科研条件保障项目(20191004022TC)。
关键词
测量
太赫兹时域光谱技术
光学延迟线
等效采样
延迟距离
延迟时间
measurement
terahertz time-domain spectroscopy technology
optical delay line
equivalent sampling
delay distance
delay time
