ATI: Backscattering and chirping laser guide star experiments at Palomar Observatory

地面上的望远镜必须通过地球大气层的干扰来观测深空中的物体。当光穿过大气层时，由于风切变和大气层内温度和压力的变化，它会被湍流传播开来，这有效地降低了地面望远镜的分辨率。这一困难在很大程度上可以通过采用“激光导星”和“自适应光学”的相对较新的技术来克服。明亮的激光照亮了目标物体附近的一片天空。激光的光被上层大气中的原子吸收，然后被重新发射，而上层大气中有很多干扰的低层大气。然后，返回的信号可以用来跟踪光的随时间散射。自适应光学利用这些信息来调整望远镜仪器中的光学系统，使图像恢复到从大气层上方可以看到的样子。不幸的是，激光导星技术既复杂又昂贵。基布尔怀特博士正在研究一个理论上的想法，他的计算机模拟证实了这个想法，这个想法将大大增加从大气中返回的光的数量。这种增强的信号可以带来更好的信噪比和/或对大气变化的更快速的反应，所有这些都以更低的成本进行。基布尔怀特博士将修改激光，然后在帕洛马天文台的5米黑尔望远镜上使用它来测试他的想法。

Telescopes on the ground must observe objects in deep space through the interference of the earth's atmosphere. As light passes through the atmosphere it gets spread out by turbulence due to wind shear and changes in temperature and pressure within the atmospheric layers which effectively diminishes the resolving power of earth-based telescopes. This difficulty can be overcome to a large extent by relatively new techniques employing "Laser Guide Stars" and "Adaptive Optics." A bright laser illuminates a patch of sky near the target object. The laser's light is absorbed and then re-emitted by atoms in the upper atmosphere, above much of the interfering lower atmosphere. The return signal can then be used to track the time-dependent scattering of the light. Adaptive Optics uses this information to adjust optics in the telescope's instrumentation to restore the image to what would be seen from above the atmosphere. Unfortunately, Laser Guide Star technology is complex and expensive. Dr. Kibblewhite is pursuing a theoretical idea, confirmed by his computer simulations, that would significantly increase the amount of light returned from the atmosphere. This enhanced signal could then lead to better signal-to-noise and/or more rapid response to the atmosphere's changes, all at a lower cost. Dr. Kibblewhite will modify a laser and then use it on the Palomar Observatory's 5-meter Hale telescope to test his idea.