ULTRAVIOLET ABSORPTION HYGROMETER: AN IMPROVED ATMOSPHERIC MOISTURE SENSOR

THIS PROPOSAL ADDRESSES THE NEED FOR AN IMPROVED INSTRUMENT TO MEASURE ATMOSPHERIC WATER VAPOR CONTENT. THE ULTRAVIOLET ABSORPTION HYGROMETER IS DESIGNED TO FULFILL THE REQUIREMENT FOR A COMPACT, RUGGED, RELIABLE SENSOR WITH A WIDE DYNAMIC RANGE WHICH CAN BE OPERATED IN A FIELD OR LABORATORY ENVIRONMENT. THIS HYGROMETER WORKS ON THE PRINCIPLE OF THE DIFFERENTIAL ABSORPTION OF ULTRAVIOLET (UV) RADIATION AT TWO WAVELENGTHS, ONLY ONE OF WHICH IS IN A REGION OF SIGNIFICANT WATER ABSORPTION. THE RATIO OF THE INTENSITIES AT THE TWO WAVELENGTHS, AFTER TRANSMISSION THROUGH AN ATMOSPHERIC PATH, IS DIRECTLY RELATED TO THE MOISTURE CONTENT OF THE ATMOSPHERE. THE PHASE I OBJECTIVE IS THE DEMONSTRATION OF THE SENSOR CONCEPT USING A LABORATORY BREADBOARD INSTRUMENT. IN PHASE II A ULTRAVIOLET ABSORPTION HYGROMETER WOULD BE DESIGNED, CONSTRUCTED, AND TESTED.