Wang Yin, Zhao Nan-jing, Liu Wen-qing, Yu Yang, Fang Li, Meng De-shuo, Hu Li, Zhang Da-hai, Ma Min-jun, Xiao Xue, Wang Yu, Liu Jian-guo
Guang Pu Xue Yu Guang Pu Fen Xi. 2015 Feb;35(2):309-14.
In recent years, the technology of laser induced breakdown spectroscopy has been developed rapidly. As one kind of new material composition detection technology, laser induced breakdown spectroscopy can simultaneously detect multi elements fast and simply without any complex sample preparation and realize field, in-situ material composition detection of the sample to be tested. This kind of technology is very promising in many fields. It is very important to separate, fit and extract spectral feature lines in laser induced breakdown spectroscopy, which is the cornerstone of spectral feature recognition and subsequent elements concentrations inversion research. In order to realize effective separation, fitting and extraction of spectral feature lines in laser induced breakdown spectroscopy, the original parameters for spectral lines fitting before iteration were analyzed and determined. The spectral feature line of' chromium (Cr I : 427.480 nm) in fly ash gathered from a coal-fired power station, which was overlapped with another line(FeI: 427.176 nm), was separated from the other one and extracted by using damped least squares method. Based on Gauss-Newton iteration, damped least squares method adds damping factor to step and adjust step length dynamically according to the feedback information after each iteration, in order to prevent the iteration from diverging and make sure that the iteration could converge fast. Damped least squares method helps to obtain better results of separating, fitting and extracting spectral feature lines and give more accurate intensity values of these spectral feature lines: The spectral feature lines of chromium in samples which contain different concentrations of chromium were separated and extracted. And then, the intensity values of corresponding spectral lines were given by using damped least squares method and least squares method separately. The calibration curves were plotted, which showed the relationship between spectral line intensity values and chromium concentrations in different samples. And then their respective linear correlations were compared. The experimental results showed that the linear correlation of the intensity values of spectral feature lines and the concentrations of chromium in different samples, which was obtained by damped least squares method, was better than that one obtained by least squares method. And therefore, damped least squares method was stable, reliable and suitable for separating, fitting and extracting spectral feature lines in laser induced breakdown spectroscopy.
近年来，激光诱导击穿光谱技术发展迅速。作为一种新型的材料成分检测技术，激光诱导击穿光谱能够在无需任何复杂样品制备的情况下，快速、简便地同时检测多种元素，并实现对被测样品的现场、原位材料成分检测。这种技术在许多领域都极具前景。在激光诱导击穿光谱中，分离、拟合和提取光谱特征线非常重要，这是光谱特征识别及后续元素浓度反演研究的基石。为了实现激光诱导击穿光谱中光谱特征线的有效分离、拟合和提取，对迭代前光谱线拟合的原始参数进行了分析和确定。采用阻尼最小二乘法，从某燃煤电站收集的飞灰中分离出与另一谱线（FeI：427.176 nm）重叠的铬（Cr I：427.480 nm）光谱特征线并进行提取。基于高斯 - 牛顿迭代的阻尼最小二乘法在步长上加入阻尼因子，并根据每次迭代后的反馈信息动态调整步长，以防止迭代发散并确保迭代能快速收敛。阻尼最小二乘法有助于获得更好的光谱特征线分离、拟合和提取结果，并给出这些光谱特征线更准确的强度值。对含有不同铬浓度的样品中的铬光谱特征线进行了分离和提取。然后，分别使用阻尼最小二乘法和最小二乘法给出相应谱线的强度值。绘制了校准曲线，展示了不同样品中谱线强度值与铬浓度之间的关系。接着比较了它们各自的线性相关性。实验结果表明，通过阻尼最小二乘法获得的不同样品中光谱特征线强度值与铬浓度的线性相关性优于最小二乘法。因此，阻尼最小二乘法稳定、可靠，适用于激光诱导击穿光谱中光谱特征线的分离、拟合和提取。
