Boroscope-based SPIV measurement apparatus for underwater acquisitions

This document describes a protoype for a boroscope-based Stereo Particle Image Velocimetry apparatus for underwater measurements, specifically designed for towing-tank testing. The apparatus consists of a laser unit, a synchronizer, laser sheet formation equipment and cameras equipped with commercial 800mm long, 16mm diameter, rigid boroscopes. The apparatus components are mounted on a modular scaffold which can be directly connected to the ship model for towing-tank velocimetry testing. Main advantages are the flexibility of the apparatus which can be employed for testing ship model maneuver and the fact that there is no need to develop ad-hoc water-proof cameras casing, with considerable cost savings. Additional image processing is necessary to take into account the geometrical deformation introduced by the boroscope optics.