Investigation of Tracer Particles Realizing 3-Dimensional Water Flow Measurement for Augmented Swimming Training

Previous studies have revealed that understanding the 3D movement of water contributes to improving propulsion in the water when swimming. Fluid measurements are made by scattering tracer particles into a liquid, and cameras track the movement of these particles to measure the fluid's flow. Strong lasers illuminate tracer particles to make them visible to cameras, but 3D water flow measurements in wide spaces like swimming pools have not yet been successful. This can be owed to the limitations of current optical systems impacting the measurable parameters of existing methods, such as the laser capacity and lens size. Moreover, visualized tracer particles buoyed in swimming pools can affect the swimmer's view and may be harmful to humans when swallowed. Therefore, we propose a 3D water flow tracing technology with tracer particles suitable for a swimming pool. We use an optical property called optical rotation to track the tracer particles. This method would be effective in extending the measurable area of water flow than previous methods because it does not require the use of optical systems, which are technically difficult to expand. In this study, we investigated the materials and processing methods for creating tracer particles for augmented swimming training.