Passive Detector Systems for Far Infrared Fourier Transform Spectroscopy and Terahertz Imaging

现代天文学家的发现主要是利用望远镜上的灵敏照相机。这些相机类似于商用数码相机，但被设计成尽可能高效地探测来自夜空的极低亮度。此外，天文学上的许多发现都是使用照相机和望远镜来探测人眼看不见的光，如红外线和x射线辐射。物理和工程方面的技术创新导致了新型相机的发展，这些相机要么能够看到更微弱的光源，要么能够看到以前无法探测到的不同波长的光。这方面的一个例子是被称为辐射热计的灵敏探测器的发展，它被用来探测波长在1毫米左右的光，即比光学和红外辐射的波长长，但不完全是无线电波。为了探测毫米波和远红外辐射，辐射热计被冷却到非常低的温度。辐射热计和超低温冰箱设计的进步，为天文学带来了新的相机，比如夏威夷JCMT望远镜上的水肺相机，它发现了只发出这些长波光的新型星系。这些探测器也被用于安装在巨型气球上的望远镜上，比如BOOMERANG实验，首次测量了宇宙微波背景中的涟漪。正因为如此，欧洲航天局将于2008年发射的下两个太空望远镜，普朗克和赫歇尔望远镜将使用这些超冷辐射热计。有利于天文学的技术进步也可以应用于其他领域。显然，x射线照相机对空间天文学和医学物理学都很有用。设计用于检测波长为0.01毫米的光的测热仪相机已经上市，用于“热成像”或红外夜视。在这项研究中，我们将寻求开发新的探测器，以弥补红外测热仪相机和天文测热仪相机之间的差距。这个间隙对应于频率从0.1-10太赫兹的光，被称为“太赫兹间隙”。世界上有许多研究小组正在致力于开发这些波长的技术，因为它是少数几个尚未被天文学家或工业界充分利用的电磁频谱区域之一。

Modern astronomers make their discoveries primarily using sensitive cameras attached to telescopes. These cameras are similar to commercial digital cameras but are designed to be as efficient as possible at detecting the very low light levels coming from the night sky. Also, many discoveries in astronomy are made using cameras and telescopes that detect light that is invisible to the human eye such as infrared and X-ray radiation. Technological innovation in physics and engineering leads to the development of new cameras that either have the ability to see fainter sources or to see different wavelengths of light previously undetected. One example of this is the development of sensitive detectors called bolometers that have been used detect light with wavelengths on the order of 1 mm - i.e. longer wavelength than optical and infrared radiation but not quite radio waves. To detect mm-wave and far-infrared radiation, bolometers are cooled to very low temperatures. Advances in the design of bolometers and in very cold refrigerators led to new cameras for astronomy such as the SCUBA camera on the JCMT telescope in Hawaii that discovered new types of galaxies that only give off light at these long wavelengths. These detectors also were used on telescopes attached to giant balloons such as the BOOMERANG experiment to measure the ripples in the cosmic microwave background for the first time. Because of this, the next two space telescopes to be launched by the European Space Agency in 2008, the PLANCK and HERSCHEL telescopes will use these ultra-cold bolometers. Technological advances that benefit astronomy also can have applications in other areas. Obviously, X-ray cameras are useful for both space-astronomy and medical physics. Bolometer cameras designed to detect light with wavelength of 0.01 mm are commercially available and used to for 'thermal imaging' or infrared night vision. In this research, we will be looking to develop new detectors that bridge the gap between the infrared bolometer cameras and the astronomical bolometer cameras. This gap corresponds to light with frequencies from 0.1-10 THz and is known as the 'THz gap'. There are many research groups in the world now working to develop technologies for these wavelengths as it is one of the few regions of the electromagnetic spectrum yet to be fully exploited either by astronomers or by industry.