BAE Systems of Nashua, N.H., has received $54 million in US Army contracts. The company will provide the military with four multiband lasers, which will replace infrared jam laser and flashlamp systems currently used to defend helicopters against heat-seeking missiles. Intended for use in the Advanced Threat Infrared Countermeasures/Common Missile Warning System program, the lasers are expected to offer improved performance, reliability and efficiency.