Device Design and System Integration of a Two-Axis Water-immersible Micro Scanning Mirror (WIMSM) to Enable Dual-modal Optical and Acoustic Communication and Ranging for Underwater Vehicles

To address the communication and ranging challenges caused by underwater environment, we design dual modal devices for autonomous underwater vehicles (AUVs). The dual-modal design builds upon a co-axial ultrasonic and green laser beams which leverage different signal diverging patterns and different responses in the underwater environment by each modality to achieve robust adaptability. Here we report our recent progress in improving scanning and aiming capabilities for dual-modal beam steering. The core part is our Two-Axis Water-immersible Micro Scanning Mirror (WIMSM). We improve hinge design of WIMSM for larger scanning range. We incorporate high speed Hall effect sensor-based pose feedback channel to enable closed-loop scanning and aiming control. We design ultrasonic-assisted laser handshaking method to help AUVs to acquire optical underwater communication. We have prototyped our devices and tested them in a water tank. The initial results are promising.