In-Situ Hyperspectral Transmissometer for Ocean IOP Closure

The objective of this Phase II project is to build upon the success of our Phase I project developing a compact wavelength-scanning hyperspectral transmissometer to measure in-situ beam attenuation, a critical ocean inherent optical property (IOP), from ultraviolet to near infrared (approximately 360-750 nm) wavelengths at a resolution that meets the needs of NASA remote sensing missions such as PACE, GLIMR, and SBG for ocean color model development and data product validation. The sensor will utilize a broadband light source coupled to a linear variable filter to selectively scan through source wavelength ranges to transmit to the sample, with a reference detector incorporated to monitor the source output and correct for instability and drift. The light transmitted through the sample will be coupled to a spectral detector for measurement. By utilizing a wavelength-discriminating detector, we can measure both transmitted light (at the same wavelengths as the source wavelengths entering the sample volume) and inelastically-scattered light (at wavelengths greater than the source wavelengths entering the sample volume), increasing the scientific capabilities of the instrument. In Phase II, we will (1) continue our Phase I measurement R&D to refine and characterize the performance of an advanced breadboard, (2) design, build, and test a submersible prototype of the sensor, and (3) design, build, calibrate, and test two pre-commercial units. One pre-commercial unit will remain with Sequoia for local field testing and TRL 6 validation, while the other unit will be delivered to NASA at the conclusion of the project for evaluation.