CAJ | 학술논문

基于离轴积分腔输出光谱技术(OA-ICOS)的小型集成系统以工作在近红外1.531 μm附近的分布反馈式(DFB)二极管激光器为光源,测量了窒温下各种低浓度NH_3与空气的混合气.首先利用标准浓度的CO_2气体校准得到腔镜的有效反射率R为0.996 9,在此条件下,基长35.8 cm的光学谐振腔作为吸收池可得到115.46 m的吸收光程.NH_3在6 528.764cm~(-1)位置的强吸收谱线被选择用于痕最探测,在100 torr的总压力下,实验测得NH_3的探测极限为2.66 ppmv(S/N～3),之后结合波长调制技术,在信号检测通路中采用锁丰兀放大技术来实现调制信号的二次谐波检测,这可以更好地抑制背景噪声而提高探测信号的信噪比,最终将NH_3的探测极限进一步提高到0.274 ppmv(S/N～3).
기우리축적분강수출광보기술(OA-ICOS)적소형집성계통이공작재근홍외1.531 μm부근적분포반궤식(DFB)이겁관격광기위광원,측량료질온하각충저농도NH_3여공기적혼합기.수선이용표준농도적CO_2기체교준득도강경적유효반사솔R위0.996 9,재차조건하,기장35.8 cm적광학해진강작위흡수지가득도115.46 m적흡수광정.NH_3재6 528.764cm~(-1)위치적강흡수보선피선택용우흔최탐측,재100 torr적총압력하,실험측득NH_3적탐측겁한위2.66 ppmv(S/N～3),지후결합파장조제기술,재신호검측통로중채용쇄봉올방대기술래실현조제신호적이차해파검측,저가이경호지억제배경조성이제고탐측신호적신조비,최종장NH_3적탐측겁한진일보제고도0.274 ppmv(S/N～3).
A compact instrument based on the off-axis integrated-cavity output spectroscopy (ICOS) technology was developed for sensitive measurements of gas mixing ratios (ammonia in air) at room temperature by using fiber-coupled distributed feedback (DFB) diode laser operating at 1. 531 μm. The absorption line of ammonia at 6 528.764 cm~(-1) was chosen for trace detection. The mirrors' effective reflectivity R~2 of 0.996 9 was first calibrated by carbon dioxide under this condition, and the cavity 35.8 cm in length as an absorption cell could yield an optical path of presumably 115.46 m As a result, a minimum detectable concen-tration of approximately 2. 66 ppmv (S/N～3) at the total pressure of 100 torr was obtained. Then the lock-in amplifier was added in the system to acquire the second harmonic signal by combination of wavelength modulation technology, which could bet-ter suppress background noise and improve the signal-to-noise ratio, and a detection limit of 0.293 ppmv (S/N～3) was achieved eventually. This work demonstrated the potential of the system for a range of atmospheric species sensing in the future.