空间扫描型多通道光纤F-P解调系统中LED光功率自适应方法
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摘要
针对空间扫描型多通道光纤Fabry-Perot(F-P)解调系统中LED输出光功率变化及通道间光功率损耗差异引起解调系统信噪比(SNR)下降进而影响解调精度的现象,提出一种基于差分滤波法评价SNR水平的快速LED输出光功率自适应调节方法,通过模拟调光方式使低相干干涉信号维持较高的SNR水平。搭建四通道光纤F-P压力解调系统进行实验研究,结果表明,本文方法可在0.36s之内恢复链路损耗突变造成的SNR波动;在5~150kPa压力范围内,最大压力解调误差为0.038kPa,解调精度优于0.03%(F.S.)(F.S.表示全量程),与以往固定光源功率方法相比,精度提高2.28倍以上;在102kPa下采用本文方法调节后的各通道SNR均优于26.5dB,有效提高了光功率变化情况下光纤F-P系统SNR及解调精度的稳定性。
For the decrease of signal-to-noise ratio(SNR)caused by the change of light emitting diode(LED)optical power and the difference of LED power loss among different channels in space scanning multi-channel optical fiber Fabry-Perot(F-P)demodulation system,which futher decreases the demodulation accuracy,a fast self-adaptive method of LED optical output power is proposed based on the evaluation of the SNRlevel through the differential filtering method.The SNRlevel of low coherence interference signal is kept high through analog light-dimming.A four-channel fiber F-P pressure demodulation system is built to carry out experimental research.The results show that the change of SNRcaused by sudden change in the transmission path can recover in 0.36 s.When the pressure is in the range from 5kPa to 150 kPa,the maximum error of demodulation is 0.038 kPa,and the accuracy is better than 0.03%(F.S.)(F.S.is short for full scale),which is 2.28 times better than that of previous static optical power.When the pressure is 102 kPa,the SNRs of four channels are all better than 26.5dB though this proposed method,which improves the stability of the SNRand demodulation accuracy of fiber F-P system effectively when the optical power of LED changes.
For the decrease of signal-to-noise ratio(SNR)caused by the change of light emitting diode(LED)optical power and the difference of LED power loss among different channels in space scanning multi-channel optical fiber Fabry-Perot(F-P)demodulation system,which futher decreases the demodulation accuracy,a fast self-adaptive method of LED optical output power is proposed based on the evaluation of the SNRlevel through the differential filtering method.The SNRlevel of low coherence interference signal is kept high through analog light-dimming.A four-channel fiber F-P pressure demodulation system is built to carry out experimental research.The results show that the change of SNRcaused by sudden change in the transmission path can recover in 0.36 s.When the pressure is in the range from 5kPa to 150 kPa,the maximum error of demodulation is 0.038 kPa,and the accuracy is better than 0.03%(F.S.)(F.S.is short for full scale),which is 2.28 times better than that of previous static optical power.When the pressure is 102 kPa,the SNRs of four channels are all better than 26.5dB though this proposed method,which improves the stability of the SNRand demodulation accuracy of fiber F-P system effectively when the optical power of LED changes.
引文
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[2]Elster J L,Trego A,Catterall C,et al.Flight demonstration of fiber optic sensors[A].Proc.of SPIE[C].2003,5050:34-42.
[3]Richards W L,Dong G L,Piazza A,et al.Characterization of embedded fiber optic sensors in advanced composite materials for structural health monitoring[A].Proc.of SPIE[C].2004,505-512.
[4]Jiang J,Liu T,Zhang Y,et al.Parallel demodulation system and signal-processing method for extrinsic FabryPerot interferometer and fiber Bragg grating sensors[J].Optics Letters,2005,30(6):604-606.
[5]MENG Xiang-e,JIANG Jun-feng,LIU Tie-gen,et al.Mathematical model of illumination of CCD in the space scanning optical fiber Fabry-Pérot sensor demodulation system[J].Acta Optica Sinica,2012,32(11):298-304.孟祥娥,江俊峰,刘铁根,等.空间扫描型光纤法布里-珀罗传感解调系统中CCD的光照度数学模型研究[J].光学学报,2012,32(11):298-304.
[6]JIANG Jun-feng,QIN Zun-qi,WANG Shuang,et al.Research on multi-channel optical fiber Fabry-Pérot sensor demodulation system based on LED modulation and optical fiber array[J].Acta Optica Sinica,2015,35(6):40-47.江俊峰,秦尊琪,王双,等.基于LED调制和光纤阵列的多通道光纤法布里-珀罗传感解调系统研究[J].光学学报,2015,35(6):40-47.
[7]Dandliker R,Zimmermann E,Frosio G.Electronically scanned white-light interferometry:a novel noise-resistant signal processing[J].Optics Letters,1992,17(9):679-681.
[8]Belleville C,Duplain G.White-light interferometric multimode fiber-optic strain sensor[J].Optics Letters,1993,18(1):78-80.
[9]Marshall R H,Ning Y N,Jiang X,et al.A novel electronically scanned white-light interferometer using a Mach-Zehnder approach[J].Journal of Lightwave Technology,1996,14(3):397-402.
[10]Yin J,Liu T,Jiang J,et al.Wavelength-division-multiplexing method of polarized low-coherence interferometry for fiber Fabry-Perot interferometric sensors[J].Optics Letters,2013,38(19):3751-3753.
[11]ZHONG Wen-jiao,WEI Ai-xiang,ZHAO Yu.Dependence of GaN-based white LED colorimetric parameters on junction Temperature[J].Chinese Journal of Luminescence,2013,34(9):1203-1207.钟文姣,魏爱香,招瑜.结温对GaN基白光LED光学特性的影响[J].发光学报,2013,34(9):1203-1207.
[12]ZHOU Zhou,FENG Shi-wei,ZHANG Guang-chen,et al.The aging characteristics of high-power GaN-based white light-emitting diodes[J].Chinese Journal of Luminescence,2011,32(10):1046-1050.周舟,冯士维,张光沉,等.GaN基大功率白光LED的高温老化特性[J].发光学报,2011,32(10):1046-1050.
[13]JIANG Jun-feng,WU Fan,LIU Tie-gen,et al.Research on LED effect in space scanning optical fiber Fabry-Pérot sensor demodulation system[J].Acta Optica Sinica,2014,34(2):224-229.江俊峰,吴凡,刘铁根,等.空间扫描型光纤法布里珀罗传感解调中LED光源的影响研究[J].光学学报,2014,34(2):224-229.
[14]Jiang J,Wang S,Liu T,et al.A polarized low-coherence interferometry demodulation algorithm by recovering the absolute phase of a selected monochromatic frequency[J].Optics Express,2012,20(16):18117-18126.
[15]Feng L,Zhou Y,Peng Y,et al.A new analog dimming circuit used in LED driver[A].Proc.of IEEE International Conference on Solid-State and Integrated Circuit Technology.IEEE[C].2015,1-3.
[16]WU Yu-xiang,SHANG Jun,WANG Xiao-hong,et al.A light emitting diode driver based on pulse width modulation and pulse amplitude modulation diming[J].Acta Optica Sinica,2015,35(9):245-253.吴玉香,尚俊,王孝洪,等.一种基于脉冲宽度调制和脉冲幅度调制的发光二极管驱动器[J].光学学报,2015,35(9):245-253.
[17]SONG Peng-cheng,WEN Shang-sheng,GUAN Wei-peng,et al.Reducing color shift of LED by PWM dimming mode with adjustable peak current[J].Journal of Optoelectronics·Laser,2015,26(10):1895-1901.宋鹏程,文尚胜,关伟鹏,等.基于峰值电流可调的PWM调光方法减小LED漂移[J].光电子·激光,2015,26(10):1895-1901.
[18]ZHANG Jing-jing,ZHANG Tao,ZHENG Qi,et al.Radiant efficiency and thermal analysis of high-power LEDs at linear and PWM dimming modes[J].Journal of Optoelectronics·Laser,2013,24(1):50-55.张晶晶,张涛,郑奇,等.大功率LED在线性及PWM调光下的电光转换效率及热分析[J].光电子·激光,2013,24(1):50-55.
[19]Wang Y,Kan H.Influences of CCD nonlinear response on measurement of propagation factor M2 of a laser beam[J].Journal of Optics,2011,13(1):015708.
[20]JIANG Jun-feng,ZOU Sheng-liang,WANG Shuang,et al.Research on signal-to-noise ratio effect in spatial scanning optical fiber Fabry-Perot sensing demodulation system[J].Acta Optica Sinica,2015,35(11):87-94.江俊峰,邹盛亮,王双,等.空间扫描型光纤法布里-珀罗传感解调中信噪比的影响研究[J].光学学报,2015,35(11):87-94.