TBAtmoPath

The thermal-blooming components of LightLike are only available with specific permission from the government sponsor. Contact TimeLike Systems for details.

TBAtmoPath models optical propagation through atmospheric turbulence. The atmosphere is modeled using multiple "phase screens", typically 5-20, distributed along the propagation path. Each phase screen represents the cumulative optical path differences for a slab of atmosphere, and in between phase screens we perform vacuum propagations, using a two-step FFT propagator. The details of the path model (number and placement of screens, turbulence strengths, inner scale, etc.) are specified by "atmosphere specification" (an object of type AcsAtmSpec). Atmosphere specifications can be created using PropConfig, and for certain common cases (e.g. uniformed turbulence, or scaled Clear1) we have also provided a more convenient function call interface. The dimensions of each phase screen dimensions are controlled by a user-defined bounding rectangle for the region of interest at each end of the propagation path. If the specified bounds should be exceeded, each screen will be "scrolled" as necessary. AtmoPath is a composite system class, consisting of a TurbBloomAtmosphere and two PropagationControllers, and provides a simplified interface for propagation modeling options, which assumes that the same modeling options will be used in both propagation directions, including using planar reference waves and the defaults for point source and speckle modeling, with no spatial filtering or absorbing boundaries. If this is not what is desired, the user may wish to work with TurbBloomAtmosphere and PropagationController directly.

C++ type	name	value	description
Parameters
AcsAtmSpec	acsSpec		specifies all the properties of the atmospheric path model: range, turbulence distribution, number of phase screens, etc.
MtbAtmSpec	mtbSpec		specifies thermal blooming properties
int	atmoSeed	-123456789	random number seed for atmospheric phase screens
int	propnxy	512	propagation mesh dimension (for both x & y)
double	propdxy	0.01	propagation mesh spacing (for both x & y)
double	superApDiameter	1.8	used in modeling point sources and surface speckle; defines a circular region at the aperture plane which in vacuum would be uniformly illuminated
double	edgeSigma	0.05	used in modeling point sources and surface speckle; defines a gaussian round odd at the edge of the superaperture
double	xp1		used to define phase screen extents; defines lower bound in x at "platform" (z=0) end of propagation path
double	xp2		used to define phase screen extents; defines upper bound in x at "platform" (z=0) end of propagation path
double	yp1		used to define phase screen extents; defines lower bound in y at "platform" (z=0) end of propagation path
double	yp2		used to define phase screen extents; defines upper bound in y at "platform" (z=0) end of propagation path
double	xt1		used to define phase screen extents; defines lower bound in x at "target" (z=range) end of propagation path
double	xt2		used to define phase screen extents; defines upper bound in x at "target" (z=range) end of propagation path
double	yt1		used to define phase screen extents; defines lower bound in y at "target" (z=range) end of propagation path
double	yt2		used to define phase screen extents; defines upper bound in y at "target" (z=range) end of propagation path
double	screenDxy		phase screen mesh spacing
double	xReferenceFocus	0.0	used to define propagation geometry; set to zero for plane wave propagation.
double	yReferenceFocus	0.0	used to define propagation geometry; set to zero for plane wave propagation. (ignored at present)
int	locFlag	0	Low order correction flag
bool	useDispersion	false	use atmospheric dispersion calculations
double	nominalWavelength	0.0	nominal wavelength (m) for dispersion calculations
Inputs
Light	incomingIncident	Light()	Describes all light incident from the "incoming" direction
Light	outgoingIncident	Light()	Describes all light incident from the "outgoing" direction
Outputs
Light	incomingTransmitted		Describes all light transmitted in the "incoming" direction
Light	outgoingTransmitted		Describes all light transmitted in the "outgoing" direction