Investigating the interaction between laser parameters for ultra-fast laser processing of glass

这是一个物理学博士研究项目。该项目的目标是为玻璃（特别是熔融二氧化硅和硼硅酸盐）的超短激光材料改性提供经验模型。要做到这一点，学生将需要：-通过后处理分析（例如SEM，显微镜和相显微镜）和原位诊断的组合来表征激光对玻璃的影响。-表征将包括测量关键特征（如有效温度屏障、残余应力和玻璃改性的物理尺寸）。-现场诊断测试预计包括相位全息、温度和吸收测量。-通过应用为制造/工程过程开发的实验设计流程，将显著减少要执行的实验数量。田口法已被初步确定为一种合适的方法，但学生将被要求进行文献综述，其中包括对潜在方法的调查，作为项目的起点。结合实验设计、表征和诊断，学生将评估一系列参数对激光材料过程的影响。这将包括但不限于：峰值脉冲功率，脉冲能量，脉冲持续时间，重复率，扫描速度，脉冲重叠平均功率和聚焦光斑大小。预计学生将在项目过程中确定进一步的参数。然后可以应用方差分析（或其他适当的统计方法）将这些数据减少到一个经验模型（方程），将“制造”（即激光材料相互作用）结果等同于输入参数。理想情况下，这将产生一个等式，允许操作员为期望的结果“拨入”一组适当的参数，而不需要进行重要的过程开发测试。这些实验所需的设备将包括现有的ps/fs激光加工系统（Trumpf Tru Micro, Light conversion Carbide）以及正在采购的新激光系统，该系统将于2019年年中安装。表征工作将使用现有的成像系统（SEMS，显微镜等）以及已在相关项目中使用的偏光镜进行。诊断工作将依赖于一系列新仪器：高温计将提供温度数据，集成球吸收数据，最后全息成像系统（剑桥技术工厂，猎鹰相机）将提供现场相位信息。在很大程度上，学生将负责调试/调整这些设备以用于此应用程序。

This is a PhD research project in Physics. The project aim is to produce an empirical model for ultra-short laser material modification of glass (and specifically fused silica and borosilicate). To accomplish this the student will need to:-Characterise the effect of the laser on the glass through a combination of post process analysis (e.g. SEM, microscopy and phase microscopy) and in situ diagnostics. -Characterisation will include measuring key features (such as fictive temperature barriers, residual stress and physical dimensions of the glass modification.-In-situ diagnostic tests are expected to include phase holography, temperature and absorption measurements. -Significant reduction in the number of experiments to be performed will be achieved through the application of experimental design processes developed for manufacturing/engineering processes. The Taguchi method has been tentatively identified as a suitable approach however the student will be expected to carry out a literature review which will include a survey of potential methods as the starting point for the project. With a combination of experimental design, characterisation and diagnostics the student will assess the impact of a range of parameters on the laser-material process. This will include but will not be limited to: peak pulse power, pulse energy, pulse duration, repetition rate, scan speed, pulse overlap average power and focussed spot size. It is expected that the student will identify further parameters over the course of the project. ANOVA (or other statistical approaches as identified as appropriate) can then be applied to reduce these data to an empirical model (equation) equating the "manufacturing" (i.e. laser material interaction) result to the input parameters. Ideally this would produce an equation allowing an operator to "dial in" an appropriate set of parameters for a desired result without the need for significant process development tests. The equipment required for these experiments will include the existing ps/fs laser processing systems (Trumpf Tru Micro, Light Coversion Carbide) as well as a new laser system which is in the process of being procured for installation in mid-2019. Characterisation work will be carried out using existing imaging systems (SEMS, Microscopes etc.) as well as a polariscopic which has been constructed for use in a related project. Diagnostic work will rely on a series of new instruments: A pyrometer will provide temperature data, an integration sphere absorption data and finally a holographic imaging system (Cambridge TechWorks, Falcon Camera) will provide in site phase information. To a large extent the student will be responsible for commissioning/adapting these equipment for use in this application.