光学元件失调对光腔衰荡高反射率测量影响的理论分析

在利用光反馈光腔衰荡技术测量大口径光学元件反射率及其均匀性分布时,需要对光学元件进行二维扫描测量,而在扫描过程中光学元件的倾斜失调将对测量结果造成影响.本文根据失调谐振腔光束传输增广矩阵,通过数值运算模拟了在对称共焦腔和一般稳定腔情况下,光反馈衰荡腔结构中由样品倾斜失调引起的输出腔镜上光斑中心位置变化以及对反射率测量的...     

基于量子级联激光器光腔衰荡光谱技术的痕量氨气检测

采用基于红外脉冲量子级联激光器的高灵敏光腔衰荡光谱(Cavity ring-down spectroscopy)技术建立了氨气在1027 cm-1(9.7 μm)附近的吸收光谱痕量检测实验装置.使用该装置对人体口腔呼出气体以及超净实验室环境中氨气成份进行了测量和分析,氨气的检测灵敏度达到10 ppb.模拟分析了激光器光谱线宽对测量结果和系统检测灵敏度的影响,随着激光器光谱线宽的增加,测量结果偏低,系统检测灵敏度下降.为了减小光源线宽对测量结果的影响,通过修正曲线对测量数据进行修正,得到了较好的结果.     

Two Optical Feedback Schemes for Cavity Ring-down Technique for High Reflectivity Measurements

An optical feedback cavity ring-down （OF-CRD） technique employing a continuous wave Fabry—Perot （F-P） diode laser is investigated for high reflectivity measurement. Two optical feedback （OF） schemes （linear and V-shaped cavity schemes） for the OF-CRD technique are compared in both wavelength and time domains. Due to the OF effect caused by retro-reflection of ring-down cavity back into the laser cavity, large resonance peaks appear in CRD signals in both the schemes. However, due to the differences in the strengths and spectra of the OF, the appearance frequencies and amplitudes of the peaks in the CRD signals in both schemes differ significantly. Simple and low-cost high reflectivity measurement apparatuses are established based on these two OF-CRD schemes and high-accuracy measurements of high reflectivity are experimentally achieved.     

基于光谱采样率的反卷积算法分析

反卷积方法是提高光谱仪分辨率的重要手段。采用空域迭代反卷积和频域维纳滤波对多纵模激光器光谱进行数据仿真,并在不同光谱仪采样率条件下,比较了迭代反卷积和维纳滤波结果。仿真结果表明,迭代反卷积和维纳滤波可以有效消除光谱仪仪器响应函数引起的光谱展宽,提高光谱仪分辨率。在光谱仪采样率低的情况下,迭代反卷积的分辨率增强效果优于维纳滤波。随着采样率的增加,维纳滤波的误差小于迭代反卷积。实验分别测量了单纵模和多纵模632.8nm He-Ne激光器光谱,并对测量结果进行反卷积处理。结果表明,低分辨率光谱仪测量的激光器光谱经反卷积处理后与高分辨率光谱仪直接测量结果一致。     

Detection of chemical warfare agents based on quantum cascade laser cavity ring-down spectroscopy

Chemical warfare agents(CWAs) are recognized as serious threats of terrorist acts against the civilian population.Minimizing the impact of these threats requires early detection of the presence of CWAs.Cavity ring-down spectroscopy(CRDS) is an exquisitely sensitive technique for the detection of trace gaseous species.In this letter,the CRDS technique is employed using a pulsed quantum cascade laser for the detection of dimethyl methylphosphonate(DMMP).A limit of DMMP detection of approximately 77 ppb is achieved.The best achievable sensitivity that corresponds to noise-equivalent absorption is approximately 2×10-7cm 1.     

光学元件失调对光腔衰荡高反射率测量影响的理论分析

在利用光反馈光腔衰荡技术测量大口径光学元件反射率及其均匀性分布时,需要对光学元件进行二维扫描测量,而在扫描过程中光学元件的倾斜失调将对测量结果造成影响.本文根据失调谐振腔光束传输增广矩阵,通过数值运算模拟了在对称共焦腔和一般稳定腔情况下,光反馈衰荡腔结构中由样品倾斜失调引起的输出腔镜上光斑中心位置变化以及对反射率测量的影响.仿真结果表明:对称共焦腔情况下,输出腔镜上奇数次光斑无漂移,偶数次光斑漂移量为固定值|在一般稳定腔情况下,输出腔镜上奇偶数次光斑均往复振荡漂移.分析表明,该系统对样品失调角度的敏感程度与样品在腔内的位置以及腔长有关,通过改变样品在腔内位置,选择适当腔长以及包络拟合法可以减小样品失调对测量结果的影响.