Enhancing GBT metrology to support high resolution 3mm molecular imaging for the U.S. Community

增强 GBT 计量学，支持美国社区的高分辨率 3mm 分子成像

• 批准号: 1836009
• 负责人: Felix Lockman
• 金额: $ 134.59万
• 依托单位: Associated Universities, Inc.
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-15 至 2022-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1836009&HistoricalAwards=false
• 关键词: Enhancing; GBT; metrology; support; resolution

The Green Bank Telescope (GBT) is the world's largest fully-steerable telescope and a unique asset for the US scientific community. Its surface, which is larger than a football field, must be adjusted very precisely to bring the incoming radio waves into focus, so the surface was designed with more than 2000 individual panels mounted on precise motors. The motors can move the panels to compensate for any deviations from the perfect shape. While this works quite well at night, it can be very difficult to make this adjustment during daylight hours, when sunlight falling on different parts of the dish causes temperature changes and unpredictable distortions that cannot currently be measured. These distortions limit use of the GBT at its highest operating frequencies, where tolerances on surface accuracy are the tightest. The current project will implement a laser ranging measurement system on the GBT that will measure any surface distortions very accurately, allowing the GBT to be focused precisely both day and night. This will increase the available usable time of the telescope at its highest operating frequencies by as much as 1,000 hours every year, with a corresponding increase in the scientific output of the GBT and its utility to the US scientific community for a broad range of investigations. The Green Bank Observatory also supports a wide range of public outreach activities through its visitor center. Enhancements to the Green Bank Telescope (GBT) metrology system are planned that will enable expanded operation in the 3mm wavelength band during daylight hours. This work will increase the usable telescope time at 3mm by as much as a factor of two, and increase available time on the molecule-rich inner Galactic plane and the Galactic center by up to a factor of four. Recent technological advances in commercial metrology make it possible to purchase a Terrestrial Laser Scanner (TLS) which, when mounted near the prime focus of the GBT, can scan the entire dish in one to two minutes, producing ~10 million data points with individual range accuracies of the order of a few mm. A least-squares fit to these data provides an estimate of the surface with accuracies ~30 microns rms, significantly better than the current method of "out-of-focus holography" and well in excess of the accuracy needed. The measured surface would be compared to the ideal surface to produce commands to the surface panel actuators to compensate for the thermal distortions.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

绿岸望远镜(GBT)是世界上最大的全定向望远镜，也是美国科学界的独特资产。它的表面比足球场还大，必须非常精确地调整才能使传入的无线电波聚焦，因此表面设计了2000多个安装在精密电机上的独立电池板。马达可以移动面板，以补偿任何偏离完美形状的偏差。虽然这在晚上效果很好，但在白天进行这种调整可能非常困难，因为阳光照射在盘子的不同部分会导致温度变化和目前无法测量的不可预测的扭曲。这些失真限制了GBT在其最高工作频率下的使用，而GBT的表面精度公差是最严格的。目前的项目将在GBT上实施激光测距测量系统，该系统将非常精确地测量任何表面扭曲，使GBT能够在白天和晚上精确聚焦。这将使望远镜在其最高工作频率下的可用时间每年增加多达1000小时，同时GBT的科学产出及其对美国科学界进行广泛调查的效用也将相应增加。绿岸天文台还通过其游客中心支持广泛的公共外展活动。计划对绿岸望远镜(GBT)计量系统进行改进，使其能够在白天扩大在3毫米波长范围内的运行。这项工作将使3毫米的可用望远镜时间增加2倍，在分子丰富的内银河系平面和银河系中心的可用时间增加4倍。商业计量的最新技术进步使人们有可能购买地面激光扫描仪(TLS)，当安装在GBT主焦点附近时，可以在一到两分钟内扫描整个碟子，产生约1000万个数据点，单个距离精度为几毫米量级。对这些数据进行最小二乘拟合后，表面的估计精度约为30微米RMS，明显好于目前的“散焦全息”方法，远远超出了所需的精度。测量的表面将与理想表面进行比较，以产生命令给表面面板执行器，以补偿热变形。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。