adaptive optics

The term adaptive optics (AO) indicates systems that correct distortions from the atmosphere using input from a sensor that measures the distortion. Typically, the sensor tracks the distortion (e.g., a slight mislocation) of a known fixed source, such as a star or even an artificial source of light reflected off the atmosphere itself from a laser. 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.

Some current and planned telescopes using adaptive optics:

• Keck Observatory
• European Extremely Large Telescope (E-ELT)
• Giant Magellan Telescope (GMT)
• Thirty Meter Telescope (TMT)

Multi-conjugate AO is adaptive optics that is specifically designed to correct for distortion at multiple distances from the telescope.