|Model of the European Extremely Large Telescope (E-ELT) which should go into operation in the early 2020s. Its primary mirror will have a diameter of 39 meters. Compare its size to that of the Munich football stadium.|
The sharpness of the images is not only influenced by the point spread function but also by blurring through turbulences in the atmosphere. Adaptive optics uses deformable mirrors to correct blurred images.
If there were no atmosphere, the incoming wavefronts from a star to be observed would be parallel. The deformable mirror, optimally adjusted, corrects the perturbations. These perturbations change, more or less, continuously so that the actuator commands for the deformable mirror have to be calculated with a frequency of 500 to 3000 Hertz.
Next: SCAO, MCAO and MOAO.