What is Adaptive Optics?
Adaptive optics [AO] is a technique in which optical performance is improved by manipulating the shape of the wavefront (generally using an active optical element such as a deformable mirror). AO can correct for unwanted disturbances (e.g. introduced by atmospheric turbulence, biological samples, optical elements…) but also introduce wanted disturbances. AO systems generally consist of three subsystems:
- A wavefront sensor [WFS], to detect the state of the wavefront,
- A wavefront corrector [WFC], to correct wavefront distortions,
- A control system to link the two.
AO was first proposed by Babcock (1953) and independently by Linnick (1957) to improve quality of astronomical images. At the time, development costs and time were too prohibitive to achieve the construction of an AO system for astronomy. Nonetheless, by the end of the 1970s, defence industries were widely developing AO techniques and technology to compensate effects of atmospheric turbulence.
The first astronomical prototype was constructed in the early 1990s, and AO now equips all major instruments in the world. More recently, driven by new computing power and low-cost technologies both for WFS and WFC devices, similar techniques have been applied in a range of other applications such as microscopy, ophthalmology, defence, manufacturing, consumer devices or communications. The growth of AO technologies and know-how makes adaptive optics emerge from its historic areas of application and expend to new markets.