Editorial

摘要

Adaptive optics (AO) systems are used in astronomy to compensate for the image deformations induced by atmospheric turbulence, the major factor limiting the resolution of ground-based telescopes. Atmospheric turbulence produces variations in light intensity (which make star twinkle), and adds a time-varying turbulent phase to the image wavefront entering the telescope's pupil. AO systems rely on a deformable mirror (DM) inserted in the telescope's optical path to compensate for these wavefront deformations in real time, using measurements of the resulting residual phase provided by a wavefront sensor (WFS). This control loop enables to drastically reduce the turbulence-induced degradation of image quality, which can be quantified by the variance of the residual phase over the imaging camera's (usually long) exposure time. This disturbance rejection strategy had been proposed by the astronomer Horace W. Babcock in the early 1950s.