Rotorcraft Airspeed Measurement System

To address the Navy"s need, Physical Optics Corporation (POC) has developed a new Rotorcraft Airspeed Measurement (RAM) system. This RAM system is based on self-mixing interference in a semiconductor laser diode. During Phase I, POC proved feasibility of the RAM system with a new velocity sensor system design, performance analysis, and assembly and testing of a RAM prototype that demonstrated wind speed measurements at a POC laboratory. This prototype has proven that RAM can measure wind speeds with greater than 2% accuracy and with a signal-to-noise ratio better than 10. The theoretical estimates have shown the optical Doppler signal is amplified by the cavity gain medium, enabling a much higher (~10^3) signal-to-noise ratio than traditional laser-based systems. Simulations for determining the optimal emitter size showed that an emitter radius larger than 2.5 cm is sufficient to achieve carrier-to-noise ratio of nearly 1000 at 15 m from the laser using 1550 nm laser wavelength. In Phase II, POC will develop a RAM prototype using a 1-W laser, enabling RAM to concurrently measure multidirectional low airspeed of rotorcraft. The resulting RAM will be ready for mass production and rapid transitioning to the Navy for deployment during AMCM missions.