def _generateSubHarmonics(self, numberOfSubHarmonics):
nSub = 3
lowFreqScreen = np.zeros((self._screenSzInPx, self._screenSzInPx),
dtype=np.complex)
freqX = bfft.frequencies_x_map(nSub, 1. / nSub)
freqY = bfft.frequencies_y_map(nSub, 1. / nSub)
freqMod = bfft.frequencies_norm_map(nSub, 1. / nSub)
vv = np.arange(self._screenSzInPx) / self._screenSzInPx
xx = np.tile(vv, (self._screenSzInPx, 1))
yy = xx.T
depth = 0
while depth < numberOfSubHarmonics:
depth += 1
phase = self._randomPhase()
freqMod /= nSub
freqX /= nSub
freqY /= nSub
modul = self._kolmogorovAmplitudeMap(freqMod)
for ix in range(nSub):
for jx in range(nSub):
sh = np.exp(2 * np.pi * 1j *
(xx * freqX[ix, jx] + yy * freqY[ix, jx] +
phase[ix, jx]))
sh0 = sh.sum() / self._screenSzInPx**2
lowFreqScreen += 1. / nSub**depth * modul[ix,
jx] * (sh - sh0)
lowFreqScreen *= np.sqrt(0.0228) * self._screenSzInPx**(5. / 6)
return lowFreqScreen
def __init__(self,
dPupInMeters,
r0At500nm,
wavelenghtInMeters,
dPupInPixels=1024,
outerScaleInMeter=1e6):
self._pupDiameterInMeters = dPupInMeters
self._r0 = r0At500nm
self._lambda = wavelenghtInMeters
self._pupDiameterInPixels = dPupInPixels
self._L0 = outerScaleInMeter
self._tb = TurbulentPhase()
self._pxSize = self._pupDiameterInMeters / self._pupDiameterInPixels
self._spat_freqs = bfft.frequencies_norm_map(self._pupDiameterInPixels,
self._pxSize)
self._dist = bfft.distances_norm_map(self._pupDiameterInPixels,
self._pxSize)
self._mapCenter = (np.asarray(self._dist.shape) / 2).astype(np.int)
self._psd = self._tb.vonKarmanPowerSpectralDensity(
self._r0, self._L0, self._spat_freqs)
self._phaseAC = bfft.direct_transform(self._psd).real
self._phaseSTF = 2 * (
self._phaseAC[self._mapCenter[0], self._mapCenter[1]] -
self._phaseAC)
self._kolmSTFInRad2 = 6.88 * (
self._dist / r0AtLambda(self._r0, self._lambda))**(5 / 3)
def testFrequenciesMapEven(self):
sz = 100
pixelSize = 1.0
freqs = bfft.frequencies_norm_map(sz, pixelSize)
self._checkFrequenciesNormMap(freqs, sz, pixelSize)
def testFrequenciesMapEvenWithPixelSize(self):
sizeInPoints = 100
pxSize = 0.1
freqs = bfft.frequencies_norm_map(sizeInPoints, pxSize)
self._checkFrequenciesNormMap(freqs, sizeInPoints, pxSize)