Definitions for "Active optics"
Corrects distortions in the shape of large, thin primary mirrors due to gravitational and structural flexing to provide a smoother surface. Typically operates at a few hertz and uses actuators to align the mirror.
The techniques by which corrections are made to the shape of a large mirror or radio dish to adjust for minute distortions in its shape. These variations arise as a telescope is subjected to forces such as gravity and temperature changes.
Collection of techniques now being used to increase the resolution of ground-based telescopes. Minute modifications are made to the overall configuration of an instrument as its temperature and orientation change, to maintain the best possible focus at all times.