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Atmospheric characterization for adaptive optics at the W. M. Keck and Hale Telescopes.

机译：W. M. Keck和Hale望远镜的自适应光学器件的大气特征。

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摘要

We have taken a variety of high speed measurements using Shack-Hartmann wavefront sensors at the W. M. Keck and Hale Telescopes to characterize the atmospheric turbulence, as well as the performance of the telescopes.; At the Keck Telescope, we used two independent methods to measure the atmospheric coherence diameter or Fried parameter, {dollar}rsb0.{dollar} By tracking the sub-image motion associated with Keck segments, the average {dollar}rsb0{dollar} was measured to be 25.4 cm with a standard deviation of 8.0 cm from 62 measurements on 14 nights. By reconstructing the wavefronts over single Keck segments using 8{dollar}sp{lcub}th{rcub}{dollar} order Zernike polynomial fitting of Shack-Hartmann data, we measured an average {dollar}rsb0{dollar} of 28.7 cm with a standard deviation of 13.1 cm from ten measurements on five nights. At the Hale Telescope, we measured an average {dollar}rsb0{dollar} of 16.3 cm with a standard deviation of 5.9 cm from 151 measurements on five nights. In addition, we discovered the Keck segments to be vibrating at 30 Hz, which causes discontinuities in the wavefront as large as 169 nm. These segment vibrations would have serious adverse consequences for the Keck adaptive optics system and therefore need to be reduced in power by nearly an order of magnitude.; When the image motions of multiple Keck segments are tracked simultaneously, these motions are less correlated than one would predict on the basis of a Kolmogorov atmosphere. The correlation analysis indicates that the outer scale of turbulence at Keck is a few hundred meters or less. This has positive implications for the stroke of both the adaptive optics tip/tilt mirror and the delay lines of the Keck interferometer.; We estimate the coma anisoplanatism error from Shack-Hartmann measurements of atmospheric coma. At Keck, the RMS atmospheric coma from both direct and indirect measurements is about 110 nm. The associated coma anisoplanatism would cause an error in the tip/tilt measurements made by a quadrant cell detector of 0.030 arcseconds; this would limit the Strehl ratio of the Keck adaptive optics system to 0.05. It may be possible to reduce this error by a factor of five using time-averaging techniques, which would increase the Strehl to 0.56.
机译：我们使用W. M. Keck和Hale望远镜的Shack-Hartmann波前传感器进行了各种高速测量，以表征大气湍流和望远镜的性能。在Keck望远镜中，我们使用了两种独立的方法来测量大气相干直径或Fried参数{dollar} rsb0。{dollar}通过跟踪与Keck分段相关的子图像运动，平均{dollar} rsb0 {dollar}为在14个晚上测量了25.4厘米，与62次测量的标准偏差为8.0厘米。通过使用Shack-Hartmann数据的8 {dollar} sp {lcub} th {rcub} {dollar}阶Zernike多项式拟合在单个Keck分段上重构波前，我们测得28.7 cm的平均{dollar} rsb0 {dollar}为与五个晚上的十次测量的标准偏差为13.1厘米。在Hale望远镜上，我们在五个晚上测量的平均{dollar} rsb0 {dollar}为16.3 cm，与151次测量的标准偏差为5.9 cm。此外，我们发现凯克线段以30 Hz的频率振动，这会导致波前的不连续性高达169 nm。这些段振动将对凯克自适应光学系统产生严重的不利影响，因此需要将功率降低近一个数量级。当同时跟踪多个Keck段的图像运动时，这些运动之间的相关性低于根据Kolmogorov气氛所预测的运动。相关分析表明，Keck湍流的外部尺度为几百米或更小。这对自适应光学头/倾斜镜和凯克干涉仪的延迟线的行程都有积极影响。我们从大气昏迷的Shack-Hartmann测量值估计昏迷各向异性。在凯克，直接和间接测量的RMS大气昏迷约为110 nm。相关的昏迷各向异性会导致象限像元检测器进行的尖端/倾斜测量误差为0.030弧秒。这会将Keck自适应光学系统的斯特列尔比限制为0.05。使用时间平均技术有可能将误差减少五分之一，这会将Strehl增加到0.56。

著录项

  • 作者

    Dekens, Frank Geeraard.;

  • 作者单位

    University of California, Irvine.;

  • 授予单位 University of California, Irvine.;
  • 学科 Physics Astronomy and Astrophysics.; Physics Atmospheric Science.
  • 学位 Ph.D.
  • 年度 1998
  • 页码 185 p.
  • 总页数 185
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 天文学;大气科学（气象学）;
  • 关键词

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