Segmented mirror
Videos
A segmented mirror is an array of smaller mirrors designed to act as segments of a single large curved mirror. The segments can be either spherical or asymmetric. They are used as objectives for large reflecting telescopes. To function, all the mirror segments have to be polished to a precise shape and actively aligned by a computer-controlled active optics system using actuators built into the mirror support cell.
Early segmented mirror, built out of 61 hexagonal segments in 1952.
SALT's segmented mirror
The Keck II telescope showing the segmented primary mirror
Mirror segments made of beryllium
Thirty Meter Telescope
Videos
The Thirty Meter Telescope (TMT) is a planned extremely large telescope (ELT) that has become controversial due to its location on Mauna Kea, on the island of Hawaiʻi. The TMT would become the largest visible-light telescope on Mauna Kea.
An artist's rendering of proposed telescope
The Thirty Meter Telescope design, late 2007
Cultural practitioner Joshua Lanakila Mangauil, along with Kahoʻokahi Kanuha and Hawaiian sovereignty supporters block the access road to Mauna Kea in October 2014, demonstrating against the building of the Thirty Meter Telescope.
Inverted flag being flown next to Mauna Kea access road as a sign of protest, September 2023