Seaver Engineering Associates proposes to develop an expendable optical sensing system to measure oceanic depth and temperature (an optical bathythermograph, BT). The commercial development of the expendable bathythermograph (XBT) in the 1960s began a revolution in the process of making oceanographic measurements. The XBT alleviated the need for a ship to stop at a location and laboriously lower and raise an instrument while recording, on deck, the measurements as they were transmitted up the electrical winch wire. The XBT is merely thrown overboard while a ship is underway and its data is tramsmitted up a thin expendable wire. The ship never stops and, as a consequence, becomes far more efficient, dramatically reducing the time per measurement and increasing the quantity of data. Literally hundreds of thousands of XBT measurements are now taken every year. The proposal by Seaver is to develop an optical expendable BT. Optics have a number of advantages over standard electromechanical measurement devices intended for ocean use including high data rates, low attenuation, light weight, non- corrosible, and unaffected by electrical grounding. Further, with costs for optical fiber continually dropping, it is quite likely that an optical system will become cheaper than present systems. Seaver demonstrated the feasibility of an optical pressure and temperature sensor in Phase I of Small Business Innovation Research (SBIR) Program. This proposal, for Phase II SBIR funding, is to develop a prototype instrument and to calibrate and test it.
