Two-component, frequency shifted LDV system for underwater applications

We propose to develop a compact, robust, and low cost diode laser-based Doppler velocimeter system capable of simultaneously measuring two velocity components with frequency shifting for resolving flow directional ambiguity. In addition to being compact, the system will require low power consumption leading to the ability of implementing multiple battery-operated probes within a constrained volume. These attributes will be possible due to an innovative frequency shifting strategy that can be implemented with low speed electronics without the detriment associated with the RF radiation of acousto-optic modulators. Furthermore, the shifted Doppler signal will also be low speed thus optimizing signal/noise of the photodetector and associated electronics.The Phase I work will consist of system modeling, design, and construction and experimental verification in a small water tank. We plan to deliver a working prototype to the Navy for testing in their water tunnel facility. Phase II will produce a complete system including signal processing electronics which should be of significant value to the Navy program.