Study On Intelligent Laser Ablation System In Mass Spectrograph

As a precision sampling technology of trace materials absorbing peak of the high-energy laser, Laser Ablation (LA) is widely used in the analysis of solid samples in semiconductor, geological, biological and environmental disciplines. The application in Mass Spectrograph (MS) of LA is a recent development for melting microsample technology, which is particularly suited to micro-samples and single-particle analysis.Laser Ablation System (LAS) is usually commercial module, whose function operation and process control are relatively independent. When used in MS, the LAS is restricted in centralized controll and coordinated operation. In addition, the 2D positioning accuracy and the camera focusing precision of LAS are not high in many MS laboratories. That makes the ablation work usually rely on manual aiming individually, and the accuracy and efficiency of ablation can not meet the current intelligent development of MS.To improve the ablation precision, efficiency and automation of the LAS in MS, this subject regarded the Inert Gas Isotope-MS in the Paleomagnetism and Geochronology Lab in Beijing (Institute of Geology and Geophysics, Chinese Academy of Science) as experimental subject, and made a study on intelligent Laser Ablation System in MS.The main research works are listed as follows:1) A two-dimensional sample worktable is redesigned, whose accuracy and performance are superior to the existing international commodity instruments. Grating ruler, motion control card and stepper motor are used in the worktable to achieve precise positioning and programmable motion control.2) To make the LAS inosculated in the detection and control of Isotope-MS, a series of control subroutine are designed, which have successfully achieved system parameters setting, system status query, system operation control, and other tasks.3) Based on two-dimensional color images detection technology, this thesis designs a new identify method of sample ablating location for this system; applies a new color image vector filter which combined the medium filter and averaging filter; puts forword a applicable color image focusing evaluation algorithm and a camera auto-focus algorithm for this system; designs a set of system calibration program for intelligent laser ablation, which uses a "â”—" zero signs for camera calibration, system zero calibration and worktable zero calibration.4) A main system control software is designed with LabVIEW 8.0. On the basis of full realization of all system control functions, the intelligent ablation process is designed from the aspects of completing manual functions, step-by-step automation, programmable automation, full automation, monitor and warning system, and so on.5) The error source analysis and experiments are performed in this thesis.