采用非稳腔结构的激光器,当系统的菲涅耳数较大时,球面腔镜尺寸随之增大,尽管可以获得高输出功率,但由于不满足傍轴条件,球面腔镜的球差对输出模式的影响变大。采用Fox-Li迭代算法,分析了腔镜类型不同时谐振腔有效菲涅耳数为675的2 k W...采用非稳腔结构的激光器,当系统的菲涅耳数较大时,球面腔镜尺寸随之增大,尽管可以获得高输出功率,但由于不满足傍轴条件,球面腔镜的球差对输出模式的影响变大。采用Fox-Li迭代算法,分析了腔镜类型不同时谐振腔有效菲涅耳数为675的2 k W射频板条CO_2激光器的输出模式,并进行了实验研究。结果表明,当腔镜采用双球面镜时球差的影响显著,输出光束近似为球面波,输出平面上光束质量因子M!2=14.48,光束质量差,聚焦后光束偏离光轴,难以实现高功率、高光束质量的激光输出;当腔镜均采用抛物面镜时球差的影响得以消除,输出光束近似为平面波,此时输出平面上光束质量得到改善,M!2=3.96,实验结果与数值模拟结果一致。展开更多
A portable dual-channel digital/analogue hybrid lock-in amplifier（LIA） is developed,and its amplitude detection error is less than 10% when the signal-to-noise ratio（SNR） is larger than-12 d B.Then,a differential ...A portable dual-channel digital/analogue hybrid lock-in amplifier（LIA） is developed,and its amplitude detection error is less than 10% when the signal-to-noise ratio（SNR） is larger than-12 d B.Then,a differential mid-infrared methane（CH4） detection device is experimentally demonstrated based on a wideband incandescence wire-source and a multi-pass spherical reflector.The experiments are carried out to obtain the sensing performance of the device.With the absorption length of only ~4.8 cm,the limit of detection（Lo D） is about 71.43 mg/m3,and the detection range is from 0 mg/m3 to 5.00×104 mg/m3.As the concentration gets larger than 714.30 mg/m3,the relative detection error falls into the range of-5%—＋5%.Two seven-hour-measurements are done on the CH4 samples with concentrations of 1.43×103 mg/m3 and 4.29×103 mg/m3,respectively,and the results show that the maximum relative error is less than 5%.Because of the cost effective incandescence wire-source,the small-size and inexpensive dual-channel LIA,and the small-size absorption pool and reflector,the developed device shows potential applications of CH4 detection in coal mine production and environmental protection.展开更多
文摘采用非稳腔结构的激光器,当系统的菲涅耳数较大时,球面腔镜尺寸随之增大,尽管可以获得高输出功率,但由于不满足傍轴条件,球面腔镜的球差对输出模式的影响变大。采用Fox-Li迭代算法,分析了腔镜类型不同时谐振腔有效菲涅耳数为675的2 k W射频板条CO_2激光器的输出模式,并进行了实验研究。结果表明,当腔镜采用双球面镜时球差的影响显著,输出光束近似为球面波,输出平面上光束质量因子M!2=14.48,光束质量差,聚焦后光束偏离光轴,难以实现高功率、高光束质量的激光输出;当腔镜均采用抛物面镜时球差的影响得以消除,输出光束近似为平面波,此时输出平面上光束质量得到改善,M!2=3.96,实验结果与数值模拟结果一致。
基金supported by the National Natural Science Foundation of China(No.61307124)the Changchun Municipal Science and Technology Bureau(No.14KG022)the Education Department of Jilin Province in China
文摘A portable dual-channel digital/analogue hybrid lock-in amplifier（LIA） is developed,and its amplitude detection error is less than 10% when the signal-to-noise ratio（SNR） is larger than-12 d B.Then,a differential mid-infrared methane（CH4） detection device is experimentally demonstrated based on a wideband incandescence wire-source and a multi-pass spherical reflector.The experiments are carried out to obtain the sensing performance of the device.With the absorption length of only ~4.8 cm,the limit of detection（Lo D） is about 71.43 mg/m3,and the detection range is from 0 mg/m3 to 5.00×104 mg/m3.As the concentration gets larger than 714.30 mg/m3,the relative detection error falls into the range of-5%—＋5%.Two seven-hour-measurements are done on the CH4 samples with concentrations of 1.43×103 mg/m3 and 4.29×103 mg/m3,respectively,and the results show that the maximum relative error is less than 5%.Because of the cost effective incandescence wire-source,the small-size and inexpensive dual-channel LIA,and the small-size absorption pool and reflector,the developed device shows potential applications of CH4 detection in coal mine production and environmental protection.
