Directed Energy Beam Jitter Mitigation Using the Line-of-Sight Reference Frame

• Main Author: Dunn, Nicholas C
• Format: Report
• Language: English
• Subjects: ACCELEROMETERS; ACTUATORS; ANGULAR RATE SENSORS; BEAM CONTROL; COMPENSATION; CONTROL SYSTEMS; Directed Energy Weapons; FAST STEERING MIRRORS; JITTER; JITTER MITIGATION; LASER BEAMS; LASERS; LINE OF SIGHT; MIRRORS; MOTION DETECTION; MOVING TARGETS; ORIENTATION DETERMINATION; ORIENTATION(DIRECTION); POSITION SENSING MODULES; TARGET TRACKING; TRACKING; VIBRATION

Directed energy weapons will dramatically increase naval capability by offering extreme precision, scalable power, speed-of-light engagement, and a nearly limitless magazine. Precise beam control is essential for maximizing the energy on target and damaging the target structure. Directed energy weapon systems operating in a maritime combat environment, however, will be mounted on dynamic platforms that are subject to jitter-inducing mechanical vibrations. Jitter is any deviation of the beam from its intended path due to platform induced vibrations or atmospheric effects. Jitter dramatically decreases the energy on target by displacing the beam from the aimpoint. The Office of Naval Research (ONR) Directed Energy Weapon Program has tasked researchers at the United States Naval Academy (USNA) to address this issue. Trident Scholar Ensign Matt Roberts developed a feed forward jitter compensation beam control system with the USNA Directed Energy Research Center that calculates and mitigates beam jitter due to platform vibrations. The purpose of this research is to increase the technology readiness level of this beam control system. Outside of the laboratory environment, off-platform orientation references are unavailable. In order to isolate the platform, on-platform angular rate sensors and linear accelerometers are used to determine platform orientation. Once platform orientation is determined, the first fast steering mirror (FSM) in the optical train can be controlled by the jitter compensation system to mitigate jitter. In maritime combat environments, targets are also rarely stationary. The line-of-sight reference frame is established to allow the second FSM to direct the beam at targets moving relative to the source platform. This research developed a beam control system that reduces the root mean square jitter angle by 50% and the jitter angle standard deviation by 60% using on-platform orientation sensors against a moving target. The original document contains color images.