d0 = PlaneD0(alpha,lambda,Geom,Lb,Atm)

Computes the section size of a laser guide star beacon (d0) given turbulence assumptions, propagation geometry, and wavelength. Output is appropriate for computing residual phase variance for compensation from laser guide star beacon as $(D/d0)^{5/3}$. Assumes the target object is at a long range compared to the beacon and hence plane wave analysis is appropriate. However, integration of Cn2 is done over the propagation path to target specified by Geom. Returns NaN if propagation path intersects earth surface.

alpha [vector] 
Multiplier on turbulence model 
lambda [scalar] 
Wavelength of laser (m) 
Geom [struct/list] 
Geometry parameters. Can be a structure from GeomStruct or a comma separated list of (...,hp,ht,rd) - not required if Atm is a structure from AtmStruct
hp [scalar] 
Altitude of transmit/receive platform (m) 
ht [scalar] 
Altitude of target (m) 
rd [scalar] 
Downrange of target along spherical earth surface (m) 
Lb [scalar] 
Slant range of beacon (m) 
Atm [struct/string] 
Atmospheric modeling parameters. Can be a structure from AtmStruct or a turbulence profile model to be used. 
Return Values
Return Values 
d0 [vector] 
LGS section size for plane wave target (m) 

  • Tyler, G. A. et al., "Adaptive Optics: Theory and Applications," Tech Rep. AFRL-DE-PS-TR-1998-1054, Air Force Research Laboratory, Directed Energy Directorate, Sec 2.5 (1999).


>> d0 = PlaneD0(1.0,1.0e-6,20e3,AtmStruct) 

  • Compute d0 at 1 micron using the turbulence model in the input Atm struct.
>> d0 = PlaneD0(2.0,1.0e-6,GeomStruct,20e3,AtmStruct) 

  • Compute d0 scaling the input turbulence model by a factor of 2 in addition to any turbulence multiplier already in the Atm struct. If Geom and geometry in Atm are not consistent, Atm will be updated.
>> d0 = PlaneD0(1.0,1.0e-6,GeomStruct,20e3,{'HufnagelValley',15,1e-15}) 

  • Passing Atm as a turbulence profile model. To pass additional parameters to the model, pass the model name and parameters in a cell array
>> d0 = PlaneD0(1.0,1.0e-6,10,10000,10000,20e3,'GreenwoodCn2') 

  • Passing geometry as a list and Atm as a turbulence profile model

See Also
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