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鉴于激光探针分辨率低的问题,提出基于远场光学技术对激光探针仪的光学系统进行改进和设计,实现了高分辨率激光探针仪的研制。研究了基于远场光学的激光探针仪的极限分辨率,采用数值孔径为0.4的反射式聚焦物镜对波长为532 nm的脉冲激光束进行聚焦,在合适能量条件下,烧蚀Al和Fe纯样表面获得的极限分辨率分别为2.26μm和1.87μm,在此极限分辨率下利用同轴光谱采集系统且能够采集到3倍于背景噪声强度的Al和Fe元素的光谱信号;设计并实现了带同轴照明的同轴共焦成像系统,视场放大率达24.7倍,采用的同轴照明系统能够有效提高摄取图像的锐度和清晰度,获得的图像分辨率不低于228 lines/mm;发明了一种带指示光的同轴光谱采集系统,能够将同轴光谱采集器与等离子体的对准误差控制在10μm以内,通过二维扫描装置,实现对等离子体表面7×9的矩形点阵列进行精确光谱采集,获得了等离子体原子光谱强度的空间分辨图像。
In view of the problem of low resolution of the laser probe, the optical system of the laser probe instrument is proposed to be improved and designed based on the far-field optical technology, and a high-resolution laser probe instrument is developed. The limit resolution of the laser probe based on far-field optics is studied. A pulsed laser beam with a wavelength of 532 nm is focused by a reflective focusing lens with a numerical aperture of 0.4. Ab and Fe pure atoms are ablated under appropriate energy conditions The ultimate resolution of the sample surface is 2.26μm and 1.87μm, respectively. At this limit resolution, a coaxial spectral acquisition system can be used to acquire spectral signals of Al and Fe with three times the background noise intensity. The design and implementation of Coaxial confocal imaging with coaxial illumination system, field of view magnification of 24.7 times, the use of coaxial illumination system can effectively improve the sharpness and sharpness of the captured image, the obtained image resolution of not less than 228 lines / mm ; Invented a coaxial optical spectrum acquisition system with indicator light, which can control the alignment error between the coaxial spectrum collector and the plasma within 10μm, and through the two-dimensional scanning device, the rectangular surface of the plasma surface of 7 × 9 Point array for accurate spectral acquisition, obtained the spatial resolution of plasma atomic spectral intensity images.