Laser-stimulated reactive atmospheric pressure plasma jet etching processes for ultra-precision processing of optical glasses (LasPlasJet)

利用局部作用的含氟大气压等离子体射流对光学表面（如透镜或镜子）进行超精密形状生成和校正，其基础是干蚀刻工艺，涉及等离子体中形成的活性物质（氟自由基）与基底表面原子之间的化学反应，形成简单硅化合物（如Si、SiO2、SiC）的挥发性产物。然而，本项目考虑的光学玻璃中还含有金属氧化物，金属氧化物在等离子体喷射蚀刻过程中也会形成不挥发的反应产物，因此无法实现均匀、暂时恒定和保持粗糙度的材料去除。因此，本研究项目旨在实验研究脉冲反应大气压等离子体射流与激光辐射在蚀刻过程中的物理和化学相互作用过程。本课题的基本挑战是在等离子体喷射蚀刻之前或之后同时或依次作用的另一种独立可调的辐射能量（即激光）的应用对复合硅基玻璃的等离子体喷射蚀刻过程的确定影响。当等离子体射流和激光辐射相结合时，等离子体射流蚀刻中附加的化学物理过程会影响近表面区域的材料成分或结构，从而影响蚀刻去除的选择性、均匀性和时空稳定性。该项目的主要目标是对复杂玻璃材料蚀刻过程中等离子体喷射和激光照射相结合的机制和过程有更深入的科学理解。下面，所获得的知识将作为计划开发用于高端光学应用的等离子体喷射/激光超精密玻璃加工方法的基础。

Ultra-precision shape generation and correction of optical surfaces such as lenses or mirrors by means of locally acting fluorine-containing atmospheric pressure plasma jets is based on a dry etching process and involves chemical reactions between the reactive species (fluorine radicals) formed in the plasma and the atoms of the substrate surface forming volatile products for simple silicon compounds, e.g. Si, SiO2, SiC. However, optical glasses considered in the project additionally contain metal oxides, which also form non-volatile reaction products during plasma jet etching, so that a uniform, temporally constant and roughness maintaining material removal cannot be achieved. Therefore, the research project aims at the experimental investigation of the physical and chemical interaction processes during the combination of pulsed reactive atmospheric pressure plasma jets and laser radiation in an etching process. The fundamental challenge of the topic is the determined influence on plasma jet based etching processes of composite, silicon based glasses by the application of a further, independently adjustable radiation energy, i.e. laser, which acts simultaneously or sequentially before or after the plasma jet etching. When plasma jet and laser radiation are combined, the additional initiation of chemical-physical processes in plasma jet etching can influence the material composition or structure in the near-surface area, so that an influence on the selectivity, homogeneity and the temporal and spatial constancy of the etch removal is expected. The main objective of the project is to gain a deeper scientific understanding of the mechanisms and processes involved in the combination of plasma jet and laser irradiation during the etching of complex glass materials. In the following, the gained knowledge will be used as a basis for the planned development of plasma jet / laser ultra-precision processing methods of glasses for high-end optical applications.