Measuring the inherent optical properties of the ocean has historically been a very difficult problem. The most widely used in-situ sensor has been the transmissometer, which measures the transmission of a light beam over a short pathlength in the water. More recently, sensors have become available that measure light absorption and optical backscattering. Absorption and beam attenuation are nonetheless still very difficult measurements to make in situ, and instruments which attempt to make these measurements require great care in their use and are difficult to calibrate. We therefore propose to investigate new approaches and techniques for measuring inherent optical properties of the ocean in situ that are robust and accurate. This study will involve numerical modeling of light propagation through ocean water under various geometries, computer-aided optical and electrical design, and some benchtop measurements with the goal of developing robust and easy to use ocean optical instruments. At the end of the Phase I effort, we will have a complete design for a new generation ocean-optical instrument that can measure relevant spectral inherent optical properties, as well as temperature and pressure, accurately and reliably. The instrument will be self-contained and compact, requiring as little as a fishing line for its deployment.
