Han Zhen-yu, Pan Cong-yuan, An Ning, Du Xue-wei, Yu Yun-si, Du Liang-liang, Wang Sheng-bo, Wang Qiu-ping
Guang Pu Xue Yu Guang Pu Fen Xi. 2015 Feb;35(2):304-8.
The present paper presents an auto-focus laser-induced breakdown spectroscopy (LIBS) remote measuring system. This system contains a Schwarzschild telescope, which consists of a convex mirror and a concave mirror. The two spherical mirrors are coaxially placed. The convex mirror is mounted on a motorized linear translation stage. With this motorized linear translation stage, the convex mirror can move along the optical axis to change the spacing between the convex mirror and the concave mirror. Therefore the focal length can be adjusted to focus the laser on samples at different distances and collect the plasma spectra. The advantages of the telescope system include, firstly, the light path of laser focusing and spectra signal collection is the same, which make it easier for mounting and collimation; secondly, the light path of the telescope uses total reflection type, which is fit for the detection in ultra-violate region; finally, the telescope consists of only two spherical mirrors which are relatively easier to manufacture. Within the translation range of the motorized linear translation stage, the focal length of the telescope in this paper can be adjusted from 1.5 to 3.6 m. The diameter of the focusing spot varies from 0.5 to 1.0 mm. Utilizing this telescope system, LIBS experiments were conducted using copper sample. And the characteristic lines of Cu element (Cu I 223.01 nm, Cu I 224.43 nm) obtained are used for the auto focusing. By investigating the relation of the area of spectral lines covered and the spacing between the mirrors, the optimal laser focusing location was obtained. The LIBS experiment results show that the system functions well, fulfilling the demand of remote ablation of sample and LIBS spectral measuring, and the telescope is able to auto-focus the laser on samples at different position to perform remote LIBS experiment.
本文介绍了一种自动聚焦激光诱导击穿光谱（LIBS）遥测系统。该系统包含一个施瓦兹希尔德望远镜，它由一个凸面镜和一个凹面镜组成。这两个球面镜同轴放置。凸面镜安装在电动直线平移台上。通过这个电动直线平移台，凸面镜可以沿光轴移动，以改变凸面镜和凹面镜之间的间距。因此，可以调节焦距，将激光聚焦在不同距离的样品上，并收集等离子体光谱。该望远镜系统的优点包括：第一，激光聚焦和光谱信号收集的光路相同，这使得安装和准直更容易；第二，望远镜的光路采用全反射型，适用于紫外区域的检测；最后，望远镜仅由两个相对容易制造的球面镜组成。在电动直线平移台的平移范围内，本文中望远镜的焦距可在1.5至3.6米之间调节。聚焦光斑的直径在0.5至1.0毫米之间变化。利用该望远镜系统，对铜样品进行了LIBS实验。所获得的Cu元素的特征谱线（Cu I 223.01 nm、Cu I 224.43 nm）用于自动聚焦。通过研究谱线覆盖面积与镜子间距之间的关系，获得了最佳激光聚焦位置。LIBS实验结果表明，该系统运行良好，满足了样品远程烧蚀和LIBS光谱测量的需求，并且该望远镜能够将激光自动聚焦在不同位置的样品上，以进行远程LIBS实验。
