Like all existing ground-based observatories, TMT will be capable of seeing-limited observations, i.e. observations with spatial resolution limited by the natural turbulence in the Earth’s atmosphere. Since such observations improve as D2, TMT will be able to observe objects nine times fainter than Keck in an equal amount of time.
However, TMT will be the first ground-based astronomy telescope designed with adaptive optics (AO) as an integral system element.
AO is a general term that covers systems designed to sense atmospheric turbulence in real-time, correct the optical beam of the telescope to remove its effect, and enable true diffraction-limited imaging on the ground. For many astronomical observations, this is equivalent to observing above the Earth’s atmosphere at a fraction of a cost of a space-based observatory. Gains improve from D2 to D4 – literally opening windows on the nearby and distant Universe inaccessible by any other observatory, on the ground or in space.
Just as the TMT primary mirror builds on the technological and operational heritage of Keck, the TMT adaptive optics design builds on the technological and operational heritage of (among others) the Gemini, Keck, and Very Large Telescope observatories. This is an area of rapid advancement and the TMT project is fortunate to have direct connections to some of the world leaders in this area (e.g. the Center for Adaptive Optics at the University of California, Santa Cruz). TMT plans are based upon an AO development roadmap that takes advantage of AO technological advances as they are being developed and applied in astronomical observations and as they are developed.
The Narrow Field Infrared Adaptive Optics System (NFIRAOS) will be the first adaptive optics system deployed on TMT. More details are available here.
A presentation at the 2010 Instrumentation Workshop about the first light adaptive optics capabilities for TMT is available here.