adaptive optics

Adaptive optics

The science of optical systems in which a controllable optical element, usually a deformable mirror, is used to optimize the performance of the system, for example, to maintain a sharply focused image in the presence of wavefront aberrations. A distinction is made between active optics, in which optical components are modified or adjusted by external control to compensate slowly changing disturbances, and adaptive optics, which applies to closed-loop feedback systems employing sensors and data processors, operating at much higher frequencies.

In a typical adaptive optics system (see illustration) the distorted light beam to be compensated is reflected from the deformable mirror and is sampled by a beam splitter. The light sample is analyzed in a wavefront sensor that determines the error in each part of the beam. The required corrections are computed and applied to the deformable mirror whose surface forms the shape necessary to flatten the reflected wavefront. The result is to remove the optical error at the sampling point so that the light passing through the beam splitter may be focused to a sharp image. Nonlinear optical devices are also capable of performing some adaptive optics functions; these devices operate at high optical power levels. See Aberration (optics), Geometrical optics, Nonlinear optics

Typical adaptive optics system using discrete components

The practical development of adaptive optics started in the late 1960s. Its main applications have been to compensate for the effects of atmospheric turbulence in ground-based astronomical telescopes and to improve the beam quality of high-power lasers. Adaptive optics is now used routinely at several astronomical observatories.

McGraw-Hill Concise Encyclopedia of Physics. © 2002 by The McGraw-Hill Companies, Inc.

adaptive optics

The techniques by which corrections may be made very rapidly (within hundredths of a second) to the shape of a mirror in order to adjust for distortions in a telescope image arising from turbulence in the Earth's atmosphere. The effects of seeing on the image are thus greatly reduced or removed. Adaptive optics are being applied to new and modernized telescopes to increase the sensitivity and spatial resolution of the telescope, and should allow near-diffraction-limited imaging over the full aperture of large optical and infrared telescopes (see Airy disk). Techniques have been developed to monitor the atmospheric disturbance on the image of a bright reference star, or on an artificial reference star (or beacon), and to make rapid compensating adjustments to the shape of a small thin deformable mirror in the light path of the telescope. See also active optics.

Collins Dictionary of Astronomy © Market House Books Ltd, 2006

adaptive optics

[ə′dap·tiv ′äp·tiks]

(optics)

The theory and design of optical systems that measure and correct wavefront aberrations in real time, that is, simultaneous with the operation of the system.

McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.