The US Air Force's Airborne Laser Program has marked another milestone with the delivery of the primary optical mirror to Contraves Brashear Systems LP in Pittsburgh. Manufactured by Corning Inc. in Corning, N.Y., the mirror will focus the system's beam on its intended target. The mirror measures 62 in. in diameter and is 8 in. thick. It will be mounted in a turret ball on the front of a modified 747-400F aircraft. The turret can be turned to track and engage missiles at extended ranges. Contraves will polish the mirror to the optical quality required to direct the laser beam to its target hundreds of kilometers away. The company anticipates it will take more than a year to complete the process.