A mirror of similar size cast of a single piece of glass could not be made rigid enough to hold its shape precisely; it would sag microscopically under its own weight as it was turned to different positions, causing aberrations in the optical path.

[2] The mirrors were made in Lexington, Massachusetts by Itek Optical Systems from Zerodur glass-ceramic by the German company Schott AG.

During observation, the computer-controlled system of sensors and actuators dynamically adjusts each segment's position relative to its neighbors, keeping a surface shape accuracy of four nanometers.

Two proposed designs for the next generation 30 and 40 m telescopes use the same basic technology pioneered at Keck Observatory: a hexagonal mirror array coupled with an altazimuth mounting.

The National Aeronautics and Space Administration (NASA) joined the partnership in October 1996 when Keck II commenced observations.

[5] Both Keck Observatory telescopes are equipped with laser guide star adaptive optics, which compensate for the blurring from atmospheric turbulence.