Astrophysics (Index)About

adaptive optics

(AO, adaptive-optics)
(optical instruments that dynamically adapt to atmospheric distortion)

The term adaptive optics (AO) indicates systems that compensate for distortions from the atmosphere using input from a sensor that measures the distortion. In particular, they detect and adjust for changing distortion due to changing air conditions. Typically, the sensor tracks the distortion (e.g., a slight mislocation) of a known fixed source, such as a star (guide star) or an artificial source of light reflected off the atmosphere itself from a laser (termed an LGS for laser guide star). This fixed source must be near the line of sight to the object under observation. The same distortion presumably affects objects in that area of the celestial sphere, including the observation target. Modern techniques include simultaneously using multiple guide stars to achieve better performance. Among the techniques are laser tomography AO (LTAO), using multiple LGSs, and multi-conjugate AO (MCAO), typically using multiple LGS plus a wavefront sensor, modeling sources of distortion at multiple distances from the telescope to better devise the optics adjustments to compensate. Single-conjagate AO (SCAO) indicates use of the wavefront sensor but without modeling more than one source of distortion. Extreme AO (XAO) uses advanced techniques and concentrates more effort on a single point within the image. XAO is associated with the use of a coronagraph, e.g., for best possible AO for direct imaging of an extra-solar planet. Some current and planned telescopes using adaptive optics:

Further reading:

Referenced by pages:
Airy disk
Canada-France-Hawaii Telescope (CFHT)
coherent light
diffraction limited
deformable mirror (DM)
European Extremely Large Telescope (E-ELT)
extremely large telescope (ELT)
ESO 3.6m Telescope
European Southern Observatory Very Large Telescope (ESO VLT)
extreme adaptive optics (ExAO)
Gemini Observatory
Giant Magellan Telescope (GMT)
Gemini Planet Imager (GPI)
guide star (GS)
Hale Telescope
high-resolution imaging
Keck Observatory
Large Binocular Telescope (LBT)
lucky imaging
Magellan Telescopes
New Technology Telescope (NTT)
Overwhelmingly Large Telescope (OWL)
speckle suppression
Strehl ratio
Subaru Telescope
Thirty Meter Telescope (TMT)
wavefront sensor
wavefront error (WFE)
William Herschel Telescope (WHT)