ASTR 151 Lecture Notes - Lecture 17: Adaptive Optics, Chicken Wire
Document Summary
Atmospheric blurring- seeing due to air movements. Seeing (angular resolution) is typically 1 arc second. Turbulence and eddies in earth"s atmosphere refract as they swirl about: pockets of air act like lenses. Affects shorter wavelengths more severely: most correction methods are done for infrared observations. Put telescopes at high altitude: avoids light-pollution, dry, clean air places. Use fancy technology to correct for atmospheric blurring: active and adaptive optics. Deformations due to changing environmental conditions, thermal expansion/contraction. Actively adapts mirror shape with actuators on an inserted correction mirror. Users a guide star (or creates an artificial one with a laser) to measure atmospheric disturbance in real time. Gets angular resolutions as low as 0. 063 which is near the diffraction limit of an 8-meter telescope at a wavelength of 1 m. Requires very powerful computers and out most advanced telescope engineering. Given radio waves" long wavelengths, radio telescopes have severe resolution challenges: greenbank radio telescope.
