A FIBER-OPTIC MICRO-SENSOR TO MEASURE THE INDEX OF REFRACTION IN SEA WATER.

INCREASINGLY SMALLER SPACE AND TIME SCALES AND ELECTROMAGNETIC CONTAMINATION HAVE BECOME BARRIERS RECENTLY IN SOME AREAS OF OCEANOGRAPHIC MEASUREMENT; THE NEED FOR AN INDEX OF REFRACTION SENSOR IS EMERGING, ALONG WITH THE TECHNICAL CAPABILITY TO PRODUCE IT. THIS PROPOSAL SEEKS TO DEVELOP A TECHNIQUE BY WHICH THE INDEX OF REFRACTION OF SEA WATER MODULATES THE WAVE LENGTH BANDWIDTH OF A CW OPTICAL SIGNAL CARRIED IN AN OPTICAL FIBER; THE BAND EDGE OF THIS OPTICAL FILTER IS DETECTED REMOTELY. THE SPECIFICATIONS OF THE PROPOSED REFRACTION SENSOR ARE: 1. ELECTROMAGNETICALLY PASSIVE; 2. ACCURACY OF 1X10(-5) OR .050PPT EQUIVALENT SALINITY; 3. SPACIAL RESOLUTION OF 0.25MM OR LESS; 4. TIME CONSTANT OF MILLISECONDS OR LESS. THE PHASE I RESEARCH GOALS ARE TO FABRICATE A SPECTROGRAPH DETECTOR AND AN OPTICAL FIBER REFRACTION SENSOR, TO LOCATE AND DEFINE THE SHARPNESS AND STABILITY OF THE BAND EDGE, AND TO OBTAIN A ROUGH CALIBRATION TO COMPARE WITH THEORY. THE IMMEDIATE USE OF THE REFRACTION MICRO SENSOR PROPOSED HEREIN WOULD BE TO MEASURE DENSITY DIRECTLY TO VERY SMALL SCALES. FROM THIS WE WOULD THEN BE ABLE TO EXTEND MICRO STRUCTURE MEASUREMENTS IN THE OCEANS TO MUCH SMALLER SCALES AND TO INVESTIGATE THE STRUCTURE OF SUCH PHENOMENON AS LABORATORY SALT FINGERS FOR THE FIRST TIME. FINALLY, AND OF MORE IMPORTANCE IN THE LONG TERM, BECAUSE OF ITS POTENTIALLY LOW COST AND STABILITY THE REFRACTION SENSOR WOULD PROVIDE THE BASIS FOR AN EXPENDABLE OPTICAL FIBER REFRACTION, TEMPERATURE, AN DEPTH INSTRUMENT (OXNTD).