Development of an ion beam sputtering process for 2 meter optics in astronomy - IBS2000

天文学中 2 米光学器件离子束溅射工艺的开发 - IBS2000

• 批准号: 452244676
• 负责人: Professor Dr. Detlev Ristau
• 金额: --
• 依托单位: Abteilung Laserkomponenten
• 依托单位国家: 德国
• 项目类别: New Instrumentation for Research
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/452244676?language=en
• 关键词: Development; ion; beam; sputtering; process

Resolution and reach of the telescopes in astronomical research depend directly on the optical design and specifically on the size of the optics. All currently planned telescopes and those under construction utilize the approach of very large primary mirrors to collect more than an order of magnitude more light and supply higher resolution. Among these are the European Extremely Large Telescope, the Thirty Meter Telescope or the Giant Magellan Telescope, to name a few.With large primary optics, of course also the instrument and detector optics follow a design of increased optical apertures compared to state-of-the-art concepts. Other than the metallic broadband reflecting mirrors of the primary optic, these instruments are in need of filter coatings that can only be realized with dielectric multi-layer coatings. For these components, selecting a specific spectral range or combining or separation of the guide star laser beam are necessary characteristics that call for complex multi-layer dielectric mirrors. For example the MAORI instrument of the E-ELT will need dichroic and filter optics in the range between 1m and 2m in diameter. These challenging optical features and the requirements in environmental stability will need a filter produced by a precise sputtering technique, others do not provide dense enough films and a stable enough production process in order to meet the spectral requirements. In specific, ion beam sputtering (IBS) is the process of choice for these kind of coatings. However, coating processes available on the commercial market only have capabilities of coating optical apertures of 500mm – 600mm in diameter, some have shown 1m on a trade fair show, but do not offer these coatings anymore. Clearly, there is no coating process available at the moment to supply the filter coatings for the astronomical instruments. Part of the reason for this is that up-scaling the coating process area is nothing that can be achieved without assisting with theoretical considerations in the process design. This work requires a simulation tool that can derive the synthesis of a dielectric film in vacuum coming from a vacuum sputter environment. In addition, the sputtering ion source needs to be designed in a way that a movement within the vacuum chamber is possible. Over the past years this expertise has been built up at Laser Zentrum Hannover and combined with a detailed experience in gridded ion sources and vacuum machine design, it is possible to develop a process that can deposit dielectric multi-layer coatings on up to 2m free apertures. By means of this large aperture IBS coating system, these required filter optics for the instruments are made possible and the full potential of these upcoming telescope systems will be accessible.

天文学研究中望远镜的分辨率和范围直接取决于光学设计，特别是光学系统的尺寸。所有目前计划中的望远镜和正在建造的望远镜都利用非常大的主镜来收集超过一个数量级的光线并提供更高的分辨率。其中包括欧洲极大望远镜、三十米望远镜或巨型麦哲伦望远镜，仅举几例。由于具有大的主光学系统，与最先进的概念相比，仪器和探测器光学系统当然也遵循增加光学孔径的设计。除了主光学器件的金属宽带反射镜之外，这些仪器还需要滤光器涂层，而滤光器涂层只能用介电多层涂层来实现。对于这些组件，选择特定的光谱范围或组合或分离的引导星星激光束是必要的特性，需要复杂的多层介质镜。例如，E-ELT的MAORI仪器将需要直径在1 m和2 m之间的二向色和滤光光学器件。这些具有挑战性的光学特征和对环境稳定性的要求将需要通过精确的溅射技术生产的滤光片，其他滤光片不能提供足够致密的膜和足够稳定的生产工艺以满足光谱要求。具体而言，离子束溅射（IBS）是这些类型的涂层的选择过程。然而，商业市场上可用的涂层工艺仅具有涂覆直径为500 mm-600 mm的光学孔径的能力，一些在贸易展览会上显示了1 m，但不再提供这些涂层。显然，目前没有涂层工艺可用于为天文仪器提供过滤涂层。其部分原因是，如果不辅助工艺设计中的理论考虑，则无法实现涂层工艺区域的扩大。这项工作需要一个模拟工具，可以得到的电介质薄膜的合成在真空中来自真空溅射环境。此外，溅射离子源需要设计成能够在真空室内移动。在过去的几年里，这一专业知识已经在汉诺威激光中心建立起来，并结合了网格离子源和真空机设计的详细经验，有可能开发出一种工艺，可以在高达2米的自由孔径上存款电介质多层涂层。通过这种大口径IBS涂层系统，这些仪器所需的滤光片成为可能，这些即将到来的望远镜系统的全部潜力将是可访问的。