A SOLID STATE SPECTRAL LINE DISCRIMINATOR FOR REMOTE SENSING OF CLOUD PROPERTIES

THE OXYGEN MOLECULE HAS A NUMBER OF WEAK ABSORPTION LINES INTHE 7000 A SPECTRAL REGION. BY COOLING, THE R1 LINE OF RUBY(A12O3 : CR+3) CAN BE SHIFTED TO COINCIDE WITH 50% ABSORPTION AT LINE CENTER IN THE SOLAR SPECTRUM. RUBY FLUORESCES WITH HIGH QUANTUM EFFICIENCY, WITH A TIME CONSTANT OF APPROXIMATELY 4 MS AT THE TEMPERATURES OF INTEREST. BY DETECTING THE RERADIATED LIGHT, THE RUBY CRYSTAL IS USED AS A TUNABLE NARROW BAND FILTER; THE BANDWIDTH CAN BE LESS THAN 0.4 A (FWHM). THE COLUMN DENSITY OF OXYGEN ALONG A GIVEN LINE OF LIGHT. TWO IMPORTANT USES OF SUCH A SENSOR ARE REMOTE SENSING FROM A SPACE PLATFORM OF CLOUD TOP HEIGHT, AND GROUND BASED ESTIMATION OF TIME DISPERSION OF A PULSE PROPOGATING THROUGH CLOUDS FROM SPACE. THE PROPOSED SPECTRAL LINE DISCRIMINATOR COULD BE VERY LIGHT WEIGHT ( 100 GM) AND HAVE LOW POWER CONSUMPTION (A FEW MW). THE RESEARCHERS PROPOSE TO TEST THIS CONCEPT IN A SIMPLE EXPERIMENTAL CONFIGURATION THAT WILL DEMONSTRATE OPERATION OF THE RUBY CRYSTAL IN THE INTENDED MODE, AND TO NUMERICALLY SIMULATE SEVERAL OF THE POSSIBLE FINAL FORMS OF THE INSTRUMENT.