Beam Control for Extended Range

An interception of fast targets early in their flight at a long range is important for national missile defense. The Airborne Laser (ABL) system is designed to shoot down theater ballistic missiles in their boost phase using a high-energy laser (HEL). A direct attack of fast targets at long ranges with the ABL places very stressing requirements on the adaptive optics (AO) system and degrades the AO performance. Target engagement using an airship-based relay mirror (RM) can extend the operational range and increase the probability to kill. Unfortunately, when an AO beacon is created by illuminating a missile body or atmospheric volume ahead of a missile tip with an uncompensated beam, the beam becomes corrupted by turbulence. A corrupted beacon beam creates an extended pattern at the target. In deep turbulence the beacon diameter exceeds the isoplanatic patch size. This effect, referred to as beacon anisoplanatism, strongly degrades the peak performance of direct attack ABL and extended range ABL. In Phase I, the concept of a multi-conjugate beacon compensation system (MCBCS) for correcting beacon anisoplanatism, as well as chromatic anisoplanatism associated with the wavelength difference between the beacon laser and high-energy laser, was developed and validated using wave optical simulation. In Phase II we will experimentally demonstrate the MCBCS concept at the ASALT laboratory at Starfire Optical Range at AFRL/DEC. This experimental demonstration will provide a basis for the development of the MCBCS prototype.