CAJ | 학술논문

针对可调谐半导体激光吸收光谱（TDLAS ）连续检测技术中，二次谐波背景信号存在漂移的现象，提出改变激光器中心电流实时提取背景信号，以消除连续检测过程中背景信号的漂移对浓度反演的影响。依据波长调制理论推导了二次谐波背景信号的理论表达式，并分析了实际情况下影响二次谐波背景信号的因素。给出激光器在不同工作温度时电流和输出光强度之间的关系曲线，并分析了改变激光器中心电流实时提取背景信号的可行性。结合背景信号搜索方法设计了基于LabVIEW的背景信号提取流程图。设计以氨气为检测对象的TDLAS实验系统，选取了氨气的吸收谱线以及对应的吸收中心电流。在激光器电流全工作区间内只存在唯一吸收峰的情况下，确定实验中各参数的数值及搜索背景的电流范围。实验结果表明：该方法可实时提取谐波背景信号。结合线性最小二乘法拟合反演可有效地减小检测误差及背景信号对浓度反演精度的影响，提高浓度的检测精度及准确性。在连续检测实验中，反演浓度的标准差由2.6883降到1.8561，减小背景信号漂移对检测浓度准确性的影响，提高了连续检测的准确性。
침대가조해반도체격광흡수광보（TDLAS ）련속검측기술중，이차해파배경신호존재표이적현상，제출개변격광기중심전류실시제취배경신호，이소제련속검측과정중배경신호적표이대농도반연적영향。의거파장조제이론추도료이차해파배경신호적이론표체식，병분석료실제정황하영향이차해파배경신호적인소。급출격광기재불동공작온도시전류화수출광강도지간적관계곡선，병분석료개변격광기중심전류실시제취배경신호적가행성。결합배경신호수색방법설계료기우LabVIEW적배경신호제취류정도。설계이안기위검측대상적TDLAS실험계통，선취료안기적흡수보선이급대응적흡수중심전류。재격광기전류전공작구간내지존재유일흡수봉적정황하，학정실험중각삼수적수치급수색배경적전류범위。실험결과표명：해방법가실시제취해파배경신호。결합선성최소이승법의합반연가유효지감소검측오차급배경신호대농도반연정도적영향，제고농도적검측정도급준학성。재련속검측실험중，반연농도적표준차유2.6883강도1.8561，감소배경신호표이대검측농도준학성적영향，제고료련속검측적준학성。
To overcome the second harmonic background signal drift in gas continuous detection based on tunable diode laser ab‐sorption spectroscopy(TDLAS) ,a new method of background elimination was proposed by changing center current of the laser . This method can eliminated the effects of background signal drifting on concentration inversion .Based on the wavelength modu‐lation theory ,the theoretical expression of the second harmonic of the background signal is derived .In addition ,the second har‐monic background signal components and the factors that affect it are described .In different working temperatures ,the relation‐ship curve between thelaser current and output light intensity .In the process of continuous detection ,we analyzes the feasibility ofchangingthe laser center current extraction of background signal .Combined with the principle of the background signal search‐ing ,the LabView flow chart was designed to search background center current .Ammonia(NH3 ) was detected by the TDLAS experimental system ,which demonstrated the feasibility of the new method .The range of experiment parameters and the range of background center current searches were determined ,in the situation that there was only one absorption line in the full laser workspace .The experimental results showed that this method realizes background signal extraction ,reduces the error of concen‐tration inversion and the effects of concentration inversion bybackground signal .Thus it improved the detection accuracy of the concentration .In the continuous detection experiment ,the standarddeviation of inversion concentration reduced from 2.688 3 to 1.856 1 ,which demonstrated that the degree of dispersion of detected concentration is reduced ,even eliminate the effects of background signal drifting on concentration inversion and the accuracy of detection is improved .This method provides an effec‐tive background drifting elimination approach for improving the detection accuracy of the concentration .