Calibration and preliminary performance of an in-water, integrated total scattering and backscattering sensor

The design and the calibration of the Beam-attenuation, b and bb Laser Underwater Environment Sensor (4BLUES), which borrows from advanced designs developed by the authors' individual groups in the course of the last two decades. The sensor features unparalleled accuracy in determining the optical scattering and backscattering coefficients, which are critical parameters for the remote sensing of water constituents and in-water bio-optical applications. Calibration procedures performed in the laboratory with spheres of known properties are presented together with an assessment of the performance in two field experiments in coastal waters. The more complex calibration of the scattering channel includes a novel inversion approach, which accounts for scattering and absorption losses along the laser-beam path. Strong agreement was observed with current advanced sensors for extinction and the backscattering measurement for one of the field experiments. Total scattering comparison with the current state of the art showed reasonable agreement (within 25%) for all stations except one, where the interpretation for the higher discrepancies is unresolved. These preliminary results suggest further assessment is warranted.