Microradiometers: Hybrid Instrument Building Blocks for Next-Generation Ocean Color Instruments

NASA has a current and next-generation requirement to collect high-quality in-situ data for the vicarious calibration of ocean color satellite sensors and to validate the algorithms that use the remotely sensed observations. As aquatic remote sensing shifts from the legacy perspective of optically simplistic open oceans toward next-generation observations of myriad optically complex water masses in the coastal zone and polar regions, instrument deployments from small platforms are a necessity. In response to this need, NASA funded the development of a new approach to measuring light: the microradiometer. A microradiometer consists of a photodetector, preamplifier with controllable gain, high resolution (24 bit) analog-to-digital converter (ADC), microprocessor, and an addressable digital port. The microradiometer interface electronics allows sensors that were not traditionally considered "radiometers" to be treated in like fashion by the system electronics, greatly simplifying the addition of other detectors, such as temperature, water pressure, platform angle, or even supply voltage and current. This latter feature inherently leads to the concept of hybrid microradiometers, and because microradiometers simply plug onto the aggregator board stack, unique configurations of hybrid sensing and detecting capabilities are readily imagined.