Ultrawide Bandwidth High Quantum Efficiency Detectors and Other Improvements to the Infrared Spatial Interferometer

美国加州大学伯克利分校研制的红外空间干涉仪是目前世界上唯一工作在9- 12um大气窗口的多口径恒星干涉仪。该仪器包括两个可移动的1.65 m口径Pfund望远镜，在10 um波长区域提供了前所未有的分辨率，在目前可用的最长基线上具有~30毫弧秒（mas）的分辨率。支助在四个领域升级三军情报局的硬件，这将大大增加其能力。第一个领域是利用一种新型外差探测器来扩展量子效率和带宽。第二个领域是升级自动导航系统，使用来自恒星的近红外辐射而不是可见光。这将允许足够短的积分时间来稳定目前观测计划中恒星的图像。此外，这将允许引导在可见光波段辐射非常弱的恒星，但在11um的强度足以用ISI观察到，如一些原行星状星云，OH/IR恒星和原恒星源。第三个领域涉及升级延迟线和相关器，以匹配现有探测器的带宽。相关器和延迟线的有效带宽约为1600 MHz，而现有探测器的有效带宽超过3000 MHz。因此，通过对系统的这一部分进行改进，可以获得显著的灵敏度增益。第四个范畴是发展威信山的场地，将至少两个方向的基线长度增加至场地所允许的最大长度，即约100米，从而将最大分辨率提高至约10米。＊＊＊

9321289 Danchi The Infrared Spatial Interferometer developed at the University of California at Berkeley is at present the world's only multi- aperture stellar interferometer operating in the 9-12 um atmospheric window. This instrument, involving two movable 1.65 m aperture Pfund telescopes, offers unprecedented resolution in the 10 um wavelength region with an ~30 milli-arcsec (mas) resolution at the longest currently available baseline. Support is provided for upgrades to the hardware of the ISI in four areas that would significantly add to its capabilities. The first area is to extend the quantum efficiency and bandwidth with a new type of heterodyne detector. The second area is to upgrade the autoguiding system to use the near-infrared radiation from the stars rather than visible light. This would allow sufficiently short integration times for tip-tilt stabilization of the image for the stars in the present observing program. In addition, this would allow guiding on stars which radiate very weakly at visible wavelengths and yet are intense enough at 11 um to be observed with the ISI, such as some proto-planetary nebulae, OH/IR stars, and proto-stellar sources. The third area involves upgrading the delay line and correlator to match the bandwidth of the present detectors. The effective bandwidth of the correlator and delay line is about 1600 MHz, while the present detectors have bandwidths exceeding 3000 MHz. Thus a significant gain in sensitivity can be achieved through an improvement to this part of the system. The fourth area is to develop the site at Mt. Wilson to increase the baseline length in at least two directions to the maximum allowed by the site, which is about 100 m, increasing the maximum resolution to about 10 mas. ***