turbulence.h File Reference

Data Structures
struct	genatm_t

Functions
map_t *	genatm_simple (real r0, real L0, real slope, real dx, long nx, int seed)
dmat *	genatm_loc (loc_t *loc, real r0, real L0, real slope, int seed)
mapcell *	genscreen (genatm_t *data)
mapcell *	genscreen_str (const char *keywords)
dmat *	turbcov (dmat *r, real rmax, real r0, real L0)
void	spatial_psd (dmat **out, long nx, long ny, real dx, real strength, real L0, real fmin, real fmax, real slope, real power)
dmat *	turbpsd (long nx, long ny, real dx, real r0, real L0, real slope, real power)
real	calc_aniso (real r0, int nht, real *ht, real *wt)
real	calc_greenwood (real r0, int nps, real *ws, real *wt)
real	calc_aniso2 (real r0, int nht, real *ht, real *wt, real hc1, real hc2)

Detailed Description

Contains routines to generate atmospheric turbulence screens

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Data Structure Documentation

genatm_t

struct genatm_t

Collaboration diagram for genatm_t:

Data Fields
rand_t *	rstat	The random stream
real *	wt	The layer weights
real	r0	The Fried Parameter
real *	L0	The outer scale
real	dx	The sampling
real	fmin	Minimum spatial frequency
real	fmax	Maximum spatial frequency
real	slope	Power slope of PSD. -11/3 for Von Karman, -4 for Biharmonic. -1 for fractal.
long	nx	Number of pixels along x
long	ny	Number of pixels along y
long	nlayer	The number of layers
long	ninit	In Fractal method, the size of initial screen
long	share	Use file backend for sharing of atmosphere
dmat *	r0logpsds	Spatial PSD of log(r0) (m)=beta*f^alpha. [alpha, beta, minfreq, maxfreq]
dcell *	screen	The destination screen pointer

Function Documentation

genatm_simple()

map_t* genatm_simple	(	real	r0,
		real	L0,
		real	slope,
		real	dx,
		long	nx,
		int	seed
	)

A simpler interface to gerate a single screen.

genatm_loc()

dmat* genatm_loc	(	loc_t *	loc,
		real	r0,
		real	dsa,
		real	slope,
		int	seed
	)

Generate atmosphere and map onto loc.

genscreen()

mapcell* genscreen

(

genatm_t *

data

)

Generates multiple screens from spectrum. Note that if data->share=1, the atmosphere will be different from data->share=0 due to different algorithms used.

genscreen_str()

mapcell* genscreen_str

(

const char *

keywords

)

Generate screen according to a header. It has three possible options. 1) load from file 2) generate screen from PSD with the following keys r0 (Fried parameter) L0 (Outer scale) dx (sampling) nx (number of points) slope (optional, default is -11/3) seed (optional) 3) generate from a zernike mode with the following keys rms (in nm) mode (zernike mode) dx nx

turbcov()

dmat* turbcov	(	dmat *	r,
		real	rmax,
		real	r0,
		real	L0
	)

Compute the covariance for separation of r, and put the values in cov. In kolmogorov spectrum, the variance are defined as half of the structure function between two points separated by rmax.

spatial_psd()

void spatial_psd	(	dmat **	pout,
		long	nx,
		long	ny,
		real	dx,
		real	strength,
		real	outerscale,
		real	minfreq,
		real	maxfreq,
		real	slope,
		real	power
	)

Creates 2-d PSD at size nx*ny: psd=(strength*(f^2+L0^-2)^(slope/2))^power. Zero frequency component is in the corner P(psd,0).

Parameters

pout	Output
nx	The size
ny	The size
dx	The sampling of spatial coordinate.
strength	Strength coefficient
outerscale	Outerscale
minfreq	Low end frequency cut off
maxfreq	High end frequency cut off
slope	should be -11/3 for von karman or kolmogorov screens, or -4 for biharmonic screen (just testing only).
power	optionally do a power of psd.

turbpsd()

dmat* turbpsd	(	long	nx,
		long	ny,
		real	dx,
		real	r0,
		real	L0,
		real	slope,
		real	power
	)

Compute spatial PSD of turbulence spectrum.

calc_aniso()

real calc_aniso	(	real	r0,
		int	nps,
		real *	ht,
		real *	wt
	)

Estimate anisoplanatic angle theta0 from Fried parameter r0, layer height and weights.

calc_greenwood()

real calc_greenwood	(	real	r0,
		int	nps,
		real *	ws,
		real *	wt
	)

Estimate Green wood frequency

calc_aniso2()

real calc_aniso2	(	real	r0,
		int	nps,
		real *	ht,
		real *	wt,
		real	hc1,
		real	hc2
	)

Estimate generalized aniso angle theta2 from Fried parameter r0, and layer height and weights, and deformable mirror conjugation heights hc1 hc2 of the ground and altitude DMs.