Textron Systems, under the US Army Space and Missile Defense Command's Field Ladar Tactical Transition Demonstration program, has been evaluating coherently detected, atmospheric aerosol backscattering as a method to extend the utility of the DIAL technique. This paper present recently obtained long range, multi-wavelength DIAL measurements utilizing cloud formations and a laboratory positioned absorption test cell. Good agreement between cloud and continuous wave laboratory measurements of the absorption spectra of ammonia have been obtained.
Both EO and AO modulators can be used to extend the spectral coverage of CO<SUB>2</SUB> lasers in the 9 - 11 micrometers region. For laser radar local oscillator application, the spectral purity of the frequency shifter output must be high and can be achieved with an AO frequency shifter using a special modulator configuration and a molecular absorption technique. A 500 MHz AO frequency shifter was designed, tested and shown to have a high spectral purity at an output power level of over 50 mW with a conversion efficiency of a few percent.