INJECTION-SEEDED ALEXANDRITE RING LASER - PERFORMANCE AND APPLICATIONIN A WATER-VAPOR DIFFERENTIAL ABSORPTION LIDAR

A new laser system for use of differential. absorption lidar (DIAL) in measurements of tropospheric water vapor and temperature is introduce d. This system operates in the 720-780-nm region and is configured as an alexandrite ring laser injection seeded by a cw Ti:sapphire ring la ser. This combination provides for the necessary narrow-bandwidth, hig h-frequency stability and excellent spectral purity. A bandwidth of <5 .0 x 10(-3) cm(-1), a frequency stability of 2.1 x 10(-3) cm(-1) rms, and a spectral purity of 99.995% at 726 nm have been achieved during e xtended periods of operation. A comparison of a DIAL water-vapor measu rement with a radiosonde in the boundary layer between 500 and 2000 m was performed. The maximum deviation between the humidity profiles is 154%, the standard deviation 1.6%, and the difference between the mean values 1%.