def __init__(
self,
lam=1.3785e-10, # wavelength, meters, corresponding to 9 keV
pix=55.e-6, # detector pixel size, meters
arm=0.65, # sample-detector distance, meters
gamma=45., # degrees
delta=25., # degrees
dtheta=0.01, # degrees (this becomes the step in phi if delta = 0).
best_orthogonality=False, # leave as False unless you know what you're doing!
rocking_motor='th', # Options are 'th', 'ph'.
recipSpaceSteps=[256, 256, 70] # data array size
):
"""Initialize object with default values with:
sg = ScatteringGeometry()
or with any set of values you want, eg:
sg = ScatteringGeometry( lam=2.64e-10, arm=0.6, peak=[ 2, 0, 0 ], a0=2.32e-10 )
All the parameters you don't specify explicitly will be initialized to default values.
'rocking_motor' manually sets the rocking direction: theta motor if 'th' and phi motor if 'ph'.
Only works if 'best_orthogonality' is set to False.
The 'best_orthogonality' parameter, when True, computes the mutual orthogonality parameter
separately for a theta rocking and a phi rocking, and chooses the better one.
Doesn't apply to experimental data, where the sampling is decided during the measurement,
but helps to simulate more well-behaved Fourier volumes in BCDI. Don't set to True if
you're reconstructing scans whose experimental geometry is already known.
If False, a rocking direction of 'th' is assumed unless specified otherwise.
"""
rocking_dict = {'th': misc.Delta, 'ph': misc.Gamma}
self._lambda = lam
self._pix = pix
self._arm = arm
self._delta = delta * np.pi / 180.
self._gamma = gamma * np.pi / 180.
self._ki = (1. / self._lambda) * np.array([0., 0., 1.]).reshape(
-1, 1) # incident unit vector (3x1)
self._kf = misc.Delta(self._delta) @ misc.Gamma(
self._gamma) @ self._ki # scattered wave vector (3x1)
self._Q = self._kf - self._ki
self.detectorFrame = misc.Delta(self._delta) @ misc.Gamma(self._gamma)
detXY = self._pix / (self._lambda *
self._arm) * self.detectorFrame @ np.array(
[[1., 0., 0.], [0., 1., 0.]]).T
# the columns of this matrix are the reciprocal space steps in the detector x and y directions.
self._dtheta = dtheta * np.pi / 180.
self._recip = np.array(recipSpaceSteps).astype(float).reshape(1, -1)
Brange = np.diag(1. / self._recip.ravel())
if best_orthogonality == False:
self._Mtheta = rocking_dict[rocking_motor]
# this is the 3x1 direction of changing Q.
# Also, the NEGATIVE of the detector translation step.
self._dq = (self._Mtheta(self._dtheta) @ self._Q) - self._Q
self._Brecip = np.concatenate((detXY, -1. * self._dq), axis=1)
# The columns of this matrix are the sampling steps in 3 independent directions in reciprocal space.
# Two of these are perpendicular (i.e. detector plane) while the third is the rocking direction.
else: # used in simulations to choose the best orthogonal sampling of signal
_dq = [(_Mtheta(self._dtheta) @ self._Q) - self._Q
for _Mtheta in [misc.Gamma, misc.Delta]]
_Brecip = [np.concatenate((detXY, -1. * q), axis=1) for q in _dq]
_ortho = [np.absolute(misc.orthogonality(Bq)) for Bq in _Brecip]
_best = np.where(_ortho == max(_ortho))[0][0]
self._dq = _dq[_best]
self._Brecip = _Brecip[_best]
self._Breal = np.linalg.inv(self._Brecip).T @ Brange
# The columns of this matrix are the sampling directions in 3D real space.
self._Brecip *= 1.e-9 # scaling to nm^-1 units
self._Breal *= 1.e+9 # scaling to nm units
self.ortho = [misc.orthogonality(M) for M in self.getSamplingBases()]
# these two numbers should be as close to 1 as possible for better simulations.
return
def __init__(
self,
lam=1.3785e-10, # wavelength, meters, corresponding to 9 keV
pix=55.e-6, # detector pixel size, meters
arm=0.65, # sample-detector distance, meters
gamma=45., # degrees
delta=25., # degrees
dtheta=0.01, # degrees (this becomes the step in phi if delta = 0).
recipSpaceSteps=[256, 256, 70] # data array size
):
"""Initialize object with default values with:
sg = ScatteringGeometry()
or with any set of values you want, eg:
sg = ScatteringGeometry( lam=2.64e-10, arm=0.6, peak=[ 2, 0, 0 ], a0=2.32e-10 )
All the parameters you don't specify explicitly will be initialized to default values.
"""
self._lambda = lam
self._pix = pix
self._arm = arm
self._delta = delta * np.pi / 180.
self._gamma = gamma * np.pi / 180.
self._ki = (1. / self._lambda) * np.array([0., 0., 1.]).reshape(
-1, 1) # incident unit vector (3x1)
self._kf = misc.Delta(self._delta) @ misc.Gamma(
self._gamma) @ self._ki # scattered wave vector (3x1)
self._Q = self._kf - self._ki
self._dtheta = dtheta * np.pi / 180.
self._recip = np.array(recipSpaceSteps).astype(float).reshape(1, -1)
if self._delta == 0.: # scattering in the straight-up direction; phi motor is being rocked
self._Mtheta = misc.Gamma
else: # scattering off to the side; theta motor is being rocked
self._Mtheta = misc.Delta
self._dq = (self._Mtheta(self._dtheta) @ self._Q) - self._Q
# this is the 3x1 direction of changing Q.
# Also, the NEGATIVE of the detector translation step.
self.detectorFrame = misc.Delta(self._delta) @ misc.Gamma(self._gamma)
detXY = self._pix / ( self._lambda * self._arm ) *\
self.detectorFrame @\
np.array( [ [ 1., 0., 0. ], [ 0., 1., 0. ] ] ).T
# the columns of this matrix are the reciprocal space steps in the detector x and y directions.
self._Brecip = np.concatenate((detXY, -1. * self._dq), axis=1)
# The columns of this matrix are the sampling steps in 3 independent directions in reciprocal space.
# Two of these are perpendicular (i.e. detector plane) while the third is the rocking direction.
Brange = np.diag(1. / self._recip.ravel())
self._Breal = np.linalg.inv(self._Brecip).T @ Brange
# The columns of this matrix are the sampling directions in 3D real space.
self._Brecip *= 1.e-9 # scaling to nm^-1 units
self._Breal *= 1.e+9 # scaling to nm units
