Adaptive optics techniques are used to rapidly measure the aberrations in a light beam and then adjust the optical system to correct them. In this way it is possible to form nearly perfect images, that are as sharp as it is possible to obtain. Some pictures obtained with adaptive optics systems can be found here.

Adaptive optics techniques are currently being used on the largest ground-based astronomical telescopes to produce images at near-infrared wavelengths that are as sharp as can be obtained with the Hubble Space Telescope at visible wavelengths. Future Extremely Large Telescopes will use even more sophisticated adaptive optics systems to produce even sharper images over wider fields on the sky.

A introductory description of adaptives optics on large telescopes can be found here. A more technical description of astronomical adaptive optics is here. The theory on which these systems are based is described here

Adaptive optics techniques are used in ophthalmology and vision science to record images of the retina of the human eye that are sharp enough to allow individual rods and cones to be studied. These techniques can be used to study how the eye functions, for early diagnosis of some forms of blindness, and to improve the accuracy of refractive surgery.

Adaptive optics techniques can also be applied to laser beam shaping for a variety of laser applications.

Adaptive optics also has applications in laser counter-measures in the defence area, and for secure optical communications.