Most large telescopes on Earth use adaptive optics — mirrors that wiggle a thousand times a second — to compensate for distortion from the atmosphere that causes the familiar “twinkling” effect of stars. With the technology, fuzzy globs of starlight are transformed into sharp pinpoints. GPI will take the method a step farther, using a mirror made from advanced silicon microelectromechanical systems (MEMS) instead of glass.
The system uses two quarter-coin-size silicon wafers to erase blurred light. GPI’s computer will send electrical signals to more than 4,000 actuators to warp the super-thin mirror painted on the upper layer. To accommodate that many sensors, a conventional adaptive optics mirror would have to be more than 15 inches across, bigger than a MacBook Pro. That would make GPI far too big to fit on its intended telescope: the 8-meter Gemini South telescope in Chile. MEMS’s compact deformable mirror will provide an image much brighter and sharper than that of any other ground-based telescope.