Miniaturization: The Next Wave in Astronomical Instrumentation

摄谱仪是一种天文仪器，可将星光分为多种颜色，并对它们进行精确的定量测量。 它对于广泛的天文观测至关重要；但它复杂、笨重且昂贵。 该项目利用电信行业的光子技术来开发一种新型的天文摄谱仪。 光子技术有可能将尺寸缩小几个数量级，同时降低成本。 Veilleux 和合作者正在开发这种小型化的光子摄谱仪，以部署在望远镜上。 该演示仪器有潜力将传统的光谱仪（任何天文台的主力）转变为灵活的 21 世纪发现引擎。这些研究人员借鉴了电信行业的多项创新技术，将光谱仪小型化。 其中最重要的是光子灯笼，它是一种将来自多模光纤的光有效耦合到单模光纤的方法。 多模光纤是唯一可以在天文焦平面上使用的类型。 然而，耦合到单模光纤可以使用其他光子学创新：光纤布拉格光栅和复杂波导布拉格光栅，它们可以滤除特定波长并抑制不需要的噪声。 噪声由水蒸气/OH天空发射产生，是天文红外光谱仪中不需要的背景的主要来源。 最后的创新是阵列波导光栅——一种在硅上制造的光波电路，形成色散元件。 这些单独的组件中的每一个都是由研究人员利用其机构对制造设施的访问权限进行开发和测试的。 该项目将完成该仪器并将其部署在 4.3 m 探索频道望远镜上。 该仪器确定的科学目标包括对伽马射线爆发余辉的后续研究。 该领域在过去二十年中取得了巨大进步，并将在未来几年发挥重要作用。

A spectrograph is an astronomical instrument that divides starlight into colors and makes precise, quantitative measurements of them. It is essential for a broad range of astronomical observations; but it is complex, bulky, and expensive. This project uses photonics technology adapted from the telecommunications industry to develop a novel kind of astronomical spectrograph. Photonics technology offers the potential to reduce the size by orders of magnitude while also lowering cost. Veilleux and collaborators are developing such a miniaturized, photonic spectrograph for deployment on a telescope. This demonstration instrument has the potential to transform the traditional spectrograph, workhorse of any astronomical observatory, into a lithe 21st century discovery engine.These investigators borrow several innovations from the telecommunications industry to miniaturize a spectrograph. The essential one is a photonic lantern, which is a method of efficiently coupling light from a multi-mode fiber into a single mode fiber. Multi-mode fibers are the only type that can be used at an astronomical focal plane. However, coupling to single mode fibers enable using other photonics innovations: fiber Bragg gratings and complex waveguide Bragg gratings, which filter out specific wavelengths and suppress unwanted noise. Noise arises from water vapor / OH sky emission and is the major source of unwanted background in an astronomical IR spectrograph. The final innovation is an arrayed waveguide grating -- a lightwave circuit fabricated on silicon that forms the dispersive element. Each of these individual components has been developed and tested by the investigators using their institutional access to fabrication facilities. This project will complete the instrument and deploy it at the 4.3 m Discovery Channel Telescope. The science goals identified for the instrument included follow-up investigations of gamma-ray burst afterglows. This field has seen tremendous advance over the past two decades and will be relevant for years to come.