Near-Infrared Tip-Tilt Sensor for Laser Guide Star Adaptive Optics

通过使用激光导星自适应光学系统对分布在大望远镜口径上的湍流进行定量测量，校正地球大气对天文图像的影响的目标取得了相当大的成功。然而，激光系统本身不能探测到由大气引起的物体图像中的系综移动，如果进行这种校正，衍射受限光斑中的包围能量可能会增加40%以上。这种“倾斜/倾斜”校正只能通过使用自然导航星--望远镜视场中包含的一种相当明亮的自然星--与激光投影系统相结合才能实现。由Peter Wizinowich博士和加州天文学研究协会的合作者为夏威夷莫纳克亚的Keck 10米望远镜建造的近红外倾斜/倾斜传感器将实现这一目标。通过在K(2.2微米波长)大气传输波段工作，计划中的系统将使用直径为2角分的一到三颗恒星提供高带宽(高达1千赫)的倾斜/倾斜信息，并能够在整个视场范围内进行校正。此外，聚焦校正的时间分辨率比标准方案高得多。凯克望远镜可以说是世界上最先进、最可靠、最具科学生产力的大望远镜光学系统。管理机构的科学家和技术人员是世界上最有能力的人之一，山顶是一个杰出的观测点。普通公众可以通过各种方式获得高达30%的观测时间，因此，通过近红外倾斜/倾斜校正系统等机制改善望远镜的成像能力，将使整个美国天文学受益。这项工作的资金是由NSF的天文科学部通过其先进技术和仪器计划提供的。

The goal of correcting the Earth's atmospheric effects on astronomical images has seen considerable success through the use of laser guide star adaptive optics (AO) systems that provide a quantitative measure of the turbulence distributed over the aperture of a large telescope. However, laser systems by themselves cannot detect the ensemble shift in an object's image that is induced by the atmosphere, and the encircled energy in a diffraction-limited spot could be increased by more than 40% if this correction were made. Such a "tip/tilt" correction is only available through the use of a natural guide star - a rather bright natural star included in the telescope field of view - in tandem with the laser projection system. The near-IR tip/tilt sensor being constructed by Dr. Peter Wizinowich and collaborators of the California Association for Research in Astronomy for the Keck 10-m telescope on Mauna Kea, Hawaii will accomplish this goal. By working in the K (2.2 micron wavelength) atmospheric transmission band, the planned system will provide high bandwidth (up to 1 kHz) tip/tilt information using one to three stars in a 2 arcminute diameter area, and enable corrections over that entire field of view. Additionally, focus corrections are available at a much higher time resolution than for standard schemes.The Keck telescopes are arguably the most advanced, reliable, and scientifically productive large-telescope AO systems available anywhere in the world. Scientists and technical staff at the managing institutions are among the most capable in the world, and the mountaintop is an outstanding observing site. Up to 30% of observing time is available to the general community through various means, so improvements in the imaging capabilities of the telescopes through mechanisms like near-IR tip/tilt correction systems benefit all of U.S. astronomy. Funding for this work is being provided by NSF's Division of Astronomical Sciences through its Advanced Technologies and Instrumentation program.