Miniaturization: The Next Wave in Astronomical Instrumentation

摄谱仪是一种天文仪器，它可以把星光分成不同的颜色，并对它们进行精确的定量测量。它对于广泛的天文观测是必不可少的；但它复杂、笨重、昂贵。本项目利用电信行业的光子学技术，研制一种新型天文光谱仪。光子学技术提供了在降低成本的同时减少数量级尺寸的潜力。Veilleux和合作者正在开发这样一种小型化的光子光谱仪，可以部署在望远镜上。这个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21世纪的轻便发现引擎。这些研究人员借鉴了电信行业的一些创新，使光谱仪小型化。其中最重要的是光子灯，它是一种将多模光纤中的光有效耦合到单模光纤中的方法。多模光纤是唯一一种可以用于天文焦平面的光纤。然而，与单模光纤的耦合使得使用其他光子学创新成为可能：光纤布拉格光栅和复杂波导布拉格光栅，它们滤除特定波长并抑制不必要的噪声。噪声产生于水蒸汽/ OH天空发射，是天文红外光谱仪中不需要的背景的主要来源。最后一个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。这些单独的组件都是由调查人员利用他们的机构访问制造设施开发和测试的。该项目将完成该仪器并将其部署在4.3米的探索频道望远镜上。为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。这一领域在过去二十年中取得了巨大的进步，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.