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DIAL with heterodyne detection including speckle noise: Aircraft/shuttle measurements of O3, H2O, and NH3 with pulsed tunable CO2 lasersAtmospheric trace constituent measurements with higher vertical resolution than attainable with passive radiometers are discussed. Infrared differential absorption lidar (DIAL), which depends on Mie scattering from aerosols, has special advantages for tropospheric and lower stratospheric applications and has great potential importance for measurements from shuttle and aircraft. Differential absorption lidar data reduction involves comparing large amplitude signals which have small differences. The accuracy of the trace constituent concentration inferred from DIAL measurements depends strongly on the errors in determining the amplitude of the signals. Thus, the commonly used SNR expression (signal divided by noise in the absence of signal) is not adequate to describe DIAL measurement accuracy and must be replaced by an expression which includes the random coherent (speckle) noise within the signal. A comprehensive DIAL computer algorithm is modified to include heterodyne detection and speckle noise. Examples for monitoring vertical distributions of O3, H2O, and NH3 using a ground-, aircraft-, or shuttle-based pulsed tunable CO2 laser DIAL system are given.
Document ID
Document Type
Conference Paper
Brockman, P. (NASA Langley Research Center Hampton, VA, United States)
Hess, R. V. (NASA Langley Research Center Hampton, VA, United States)
Staton, L. D. (NASA Langley Research Center Hampton, VA, United States)
Bair, C. H. (NASA Langley Research Center Hampton, VA, United States)
Date Acquired
September 4, 2013
Publication Date
August 1, 1980
Subject Category
Report/Patent Number
Meeting Information
Intern. Conf. on Heterodyne Systems and Technol.(Williamsburg, VA)
Distribution Limits
Work of the US Gov. Public Use Permitted.

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