High-Bandwidth Steering Mirrors for Highly Coherant 150mm and 300mm Optical Beams

Precision 2-axis fine-steering mirror (FSM) applications are characterized by control bandwidths typically 3 kHz and position sensors with 0.1 microradian resolution at ±10mrad travel. LHDC's current FR150-35-ZD-RC technology achieves 1000 Hz -3 dB closed-loop servo control bandwidth of the base-referenced position servo with ±10 mrad travel. Increasingly, applications like high-energy weapons and optical communications require higher bandwidths without sacrificing resolution, sometimes with smaller travel. The ABL program prefers 5,000 Hz bandwidth and ±1 mrad travel. The proposed innovations address this need. LHDC understands that the ABL program requires an optical surface figure error of 50-100 milli-wave PV at 0.63 uM. LHDC's FSM's mirror flatness was limited by the attachment of suspension and actuator components. LHDC's 1999 Phase II JPL SBIR program recently developed an attachment technique for the FR150-35-ZD-RC which is expected to prove 50-100 milli-wave PV performance for 150mm FSM. The proposed effort provides similar solutions for the larger FR300 FSM. The innovations are a compact configuration with unique components and an advanced servo controller to achieve 5 kHz control bandwidth, 50-100 milli-wave PV flatness and sub-microradian resolution. This technology also significantly reduces size, power and mass of the FSM mechanism and control electronics.