新型的激光多普勒信号检波系统
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摘要
为解决超低频、微小振动的高精度测量与装调间的矛盾,提出了一种新型的激光多普勒信号检波系统。该系统通过一运动光栅的衍射,得到约40.5%的测量光强,用另一光栅的衍射消除两束差动光间的夹角以及光波长对测量精度的影响;频移﹑混频分开进行,保证系统装调更方便准确;用1/4波片﹑渥拉斯顿棱镜等得到相位差90°的正余弦信号,实现位移方向识别。实验得出,该系统振动频率和振幅测量精度均为1%,可测频率范围可达到0.5-500Hz,可测振幅范围:1μm-5mm。
In order to compromise the contradictions between assembling and calibration expediently and high measurement accuracy to the application of laser Doppler effect in the measurement system of ultra-low frequency weak vibration, a new demodulation system of laser Doppler signal is put forward. The system based on the diffraction of a moving grating can get 40.5% light intensity for measurement and eliminate the effect of the included angle of two differential lights and light wavelength on measurement accuracy through the diffraction of another grating. The assembling and calibration of the system can be more convenient and accurate by implementing frequency shifting and mixing respectively. Sine and cosine signals with 90° phase difference can be obtained by 1/4 wave plate and Wollaston lens, thus the directional recognition of displacement can be realized. Experiments prove that both measuring accuracy of the vibration frequency and amplitude of the system is 1% and the measurable vibration frequency range can be up to 0.5~500Hz and the measurable vibration amplitude range can be up to 1μm~5mm.
In order to compromise the contradictions between assembling and calibration expediently and high measurement accuracy to the application of laser Doppler effect in the measurement system of ultra-low frequency weak vibration, a new demodulation system of laser Doppler signal is put forward. The system based on the diffraction of a moving grating can get 40.5% light intensity for measurement and eliminate the effect of the included angle of two differential lights and light wavelength on measurement accuracy through the diffraction of another grating. The assembling and calibration of the system can be more convenient and accurate by implementing frequency shifting and mixing respectively. Sine and cosine signals with 90° phase difference can be obtained by 1/4 wave plate and Wollaston lens, thus the directional recognition of displacement can be realized. Experiments prove that both measuring accuracy of the vibration frequency and amplitude of the system is 1% and the measurable vibration frequency range can be up to 0.5~500Hz and the measurable vibration amplitude range can be up to 1μm~5mm.
引文
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[2]L E Drain.激光多普勒技术[M].王仕康,沈熊,周作元.北京:清华大学出版社,1980.50-59.L E Drain.The Laser Doppler Technique[M].WANG Shi-kang,SHEN Xiong,ZHOU Zuo-yuan.Beijing:Tsinghua University Press,1980.50-59.
[3]贺顺忠,刘金凤,蒋诚志,等.远距离高精度多普勒位移测量[J].光电工程,2004,31(6):56-59.HE Shun-zhong,LIU Jin-feng,JIANG Cheng-zhi,et al.Doppler displacement measurement with high accuracy in remote distance[J].Opto-Electronic Engineering,2004,31(6):56-59.
[4]蔡式东,邱吉衡.光相干测振测速技术[J].西部电子,1991,4(8):47-51.CAI Shi-dong,QIU Ji-heng.The oscillation and velocity measurement technique of light coherent[J].Western Electronic,1991,4(8):47-51.
[2]L E Drain.激光多普勒技术[M].王仕康,沈熊,周作元.北京:清华大学出版社,1980.50-59.L E Drain.The Laser Doppler Technique[M].WANG Shi-kang,SHEN Xiong,ZHOU Zuo-yuan.Beijing:Tsinghua University Press,1980.50-59.
[3]贺顺忠,刘金凤,蒋诚志,等.远距离高精度多普勒位移测量[J].光电工程,2004,31(6):56-59.HE Shun-zhong,LIU Jin-feng,JIANG Cheng-zhi,et al.Doppler displacement measurement with high accuracy in remote distance[J].Opto-Electronic Engineering,2004,31(6):56-59.
[4]蔡式东,邱吉衡.光相干测振测速技术[J].西部电子,1991,4(8):47-51.CAI Shi-dong,QIU Ji-heng.The oscillation and velocity measurement technique of light coherent[J].Western Electronic,1991,4(8):47-51.
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