Based in Northvale, N.J., the Inrad business unit of Photonic Products Group Inc. has been awarded a follow-on production contract of an undisclosed amount from ATK Missile Systems of Clearwater, Fla., for more than 1900 ultraviolet waveband optical filter elements for its AN/AAR-47 missile warning systems. A division of Alliant Techsystems and headquartered in Woodland Hills, Calif., ATK Missile Systems is the developer and prime contractor for the upgraded systems, which are designed to protect low- and slow-flying military or commercial aircraft from missile sources. The production release will provide systems for the US Navy and Air Force and allies' aircraft. The systems employ four sensors per aircraft, each containing several optical components. Inrad's filters, which have high-temperature and mechanical stability, are made from a synthetic crystal material specifically designed for the application.