Our presentation consists of two parts: (1) a summary review of laser Doppler principles and applications, and (2) operational design and preliminary laboratory tests of a CO2 laser system for NOAA applications

Abshire, N. L.

Derr, V. E.

Schwiesow, R. L.

NASA Technical Reports Server

LASER DOPPLER MEASUREMENT OF ATMOSPHERIC WIND VELOCITY 
R. L. Schwiesow, N. L. Abshire and V. E. Derr 
Wave Propagation Laboratory 
Environmental Research Laboratories 
National Oceanic and Atmospheric Administration 
Boulder, Colorado 80302 
ABSTRACT 
Our presentation consists of two parts: (1) a summary review of laser 
Doppler principles and applications, and (2) operational design and preliminary 
laboratory tests of a CO2 laser system for NOAA applications. 
Laser Doppler velocimeters for short range applications to water tunnels 
and seeded-flow wind. tunnels are widely used and reviewedl . The non-relati v-
istic expression for the Doppler shift, 
-+ -+ -+ VVD = (n/21T) v • (k - k) . so' 
-+ 
where n is the refractive index of the medium, v the scatterer velocity 
-+ -+ 
and k and k the scattered and incident wave vectors (21T/A) , applies to 
s 0 
both local measurement and remote measurement of flows. Remote velocity 
measurements with a single-ended system at ranges of tens of meters or more 
severely restrict the usable experimental configurations, however. We will 
critically review the atmospheric results of infrared heterodyne2 ,3, two-beam 
visible differentia14, and visible incoherent 5 detection systems, as well as 
some signal to noise calculations6 
For the measurement of wind in severe storm and boundary layer meteorology 
applications, considerations of background interference, atmospheric refractive 
index fluctuations, eye safety, laser stability and efficiency, and other 
practical concerns are properly discussed. Although a heterodyne, CO2 laser 
system is attractive for these wind measurement purposes, an analysis of 
7 expected return based on the atmospheric aerosol model of McClatchey, et al. , 
is reQuired to substantiate the adeQuacy of the techniQue. 
We will present an outline of the NOAA Doppler lidar eQuipment and exhi bit 
velocity data from a diffuse scattering source at 12 meters. Conference 
l2 
https://ntrs.nasa.gov/search.jsp?R=20160007584 2019-08-31T02:27:39+00:00Z
participants are invited to an interactive discussion of the application of 
this type of laser radar to problems such as waterspouts, thunderstorms, and 
helical rolls. 
References 
1 M. J. Rudd, Optics and Laser Tech., p. 200 (Nov. 1971). 
2 R. M. Huffaker, A. V. Jelalian, and J. A. L. Thomson, Proc. IEEE 58, 
p. 322 (1970). 
3 T. R. Lawrence, D. J. Wilson, C. E. Craven, I. P. Jones, R. M. Huffaker, 
and J. A. L. Thomson, Rev. Sci. Inst., 43, p. 512 (1972). 
4 W. M. Farmer and D. B. Brayton, Appl. Opt., 10, p. 3219 (1971). 
5 G. Benedetti-Michelangeli, F. Congeduti, and G. Fiocco, J. Atmos. Sci., 29, 
p. 906 (1972). 
6 C. M. Sonnenschein and F. A. Horrigan, Appl. Opt., 10, p. 1600 (1971). 
7 R. A. McClatchey, R. W. Fenn, J. E. A. Selby, F. E. Volz, and J. S. Garing, 
Air Force Cambridge Research Laboratories, Rept. AFCRL-7I-0279 (1971). 
13 


Laser Doppler Measurement of Atmopsheric Wind Velocity

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