DIODE LASER ABSOLUTE MOISTURE SENSOR

SOUTHWEST SCIENCES PROPOSES THE DEVELOPMENT OF A DIODE LASER-BASED MOISTURE SENSOR. THE INSTRUMENT DYNAMIC RANGE WILL SPAN WATER VAPOR MIXING RATIOS OF 100 PPM TO BETTER THAN 10 PPB. THE PLANNED INSTRUMENT DETECTS ABSOLUTE WATER VAPOR CONCENTRATIONS USING OPTICAL SPECTROSCOPY WITH A CUSTOM-FABRICATED INGAASP DIODE LASER OPERATING AT 1393 NM. OPTICAL ABSORBANCE MEASUREMENTS ARE MADE USING HIGH FREQUENCY WAVELENGTHMODULATION SPECTROSCOPY (WMS) WHICH, WE ANTICIPATE, WILL BE CAPABLE OF MINIMUM DETECTABLE ABSORBANCES BELOW 1 X 10(-5), PROVIDING A SIGNAL-TO-NOISE RATION OF FOUR FOR THE LOWEST WATER CONCENTRATIONS. DUE TO THE HIGH SENSITIVITY FOR WATER DETECTION, GREAT CARE WILL BE TAKEN TO ELIMINATE UNWANTED ABSORBANCE DUE TO WATER VAPOR OUTSIDE OF THE ACTUAL MEASUREMENT PATH. THE PHASE 1 EXPERIMENTS ARE EXPECTED TO DEMONSTRATE THE FEASIBILITY OF THE DIODE LASER-BASED SYSTEM FOR DETECTING WATER VAPOR ACCURATELY AND RAPIDLY OVER A DYNAMIC RANGE APPROACHING 10(4). THE PHASE 2 PROGRAM WILL CULMINATE IN THE DEVELOPMENT OF A FULLY AUTOMATED MOISTURE SENSOR CAPABLE OF IN-LINE OPERATION IN GAS PROCESSING ENVIRONMENTS.