def test_transmission_sampling(self):
def compute_transmission_function(n, ps, energy, material):
wedge = np.tile(np.arange(n), [n, 1]) * ps
wedge = StaticBody(wedge, ps, material=material)
return wedge.transfer((n, n), ps, energy, exponent=True)
def compute_distance(n, ps, lam, ps_per_lam):
ca = (lam / (ps_per_lam * ps)).simplified.magnitude
alpha = np.arccos(ca)
theta = np.pi / 2 - alpha
return (n * ps / (2 * np.tan(theta))).simplified
n = 32
ps = 1 * q.um
energies = np.arange(5, 30) * q.keV
energy = 10 * q.keV
lam = physics.energy_to_wavelength(energy)
# Delta causes phase shift between two adjacent pixels by 2 Pi
delta = (lam / ps).simplified.magnitude
ri = np.ones_like(energies.magnitude, dtype=np.complex) * delta + 0j
material = Material('dummy', ri, energies)
# Single object
u = compute_transmission_function(n, ps, energy, material)
self.assertFalse(physics.is_wavefield_sampling_ok(u))
# 4x supersampling => phase shift Pi/2
u = compute_transmission_function(4 * n, ps / 4, energy, material)
self.assertTrue(physics.is_wavefield_sampling_ok(u))
# 4x supersampling with 2 objects => phase shift Pi
n *= 4
ps /= 4
wedge = np.tile(np.arange(n), [n, 1]) * ps
wedge = StaticBody(wedge, ps, material=material)
u = physics.transfer_many([wedge, wedge], (n, n), ps, energy, exponent=True)
self.assertFalse(physics.is_wavefield_sampling_ok(u))
# X-ray source with a parabolic phase profile
n = 128
ps = 1 * q.um
trajectory = Trajectory([(n / 2, n / 2, 0)] * ps)
# 1 pixel per wavelength => insufficient sampling
d = compute_distance(n, ps, lam, 1)
source = BendingMagnet(2.5 * q.GeV, 150 * q.mA, 1.5 * q.T, d,
1, np.array([0.2, 0.8]) * q.mm, ps, trajectory,
phase_profile='parabola')
u = source.transfer((n, n), ps, energy, exponent=True)
self.assertFalse(physics.is_wavefield_sampling_ok(u))
# 4 pixel per wavelength => good sampling
d = compute_distance(n, ps, lam, 4)
source = BendingMagnet(2.5 * q.GeV, 150 * q.mA, 1.5 * q.T, d,
1, np.array([0.2, 0.8]) * q.mm, ps, trajectory,
phase_profile='parabola')
u = source.transfer((n, n), ps, energy, exponent=True)
self.assertTrue(physics.is_wavefield_sampling_ok(u))
def _transfer(
self,
shape,
pixel_size,
energy,
offset,
exponent=False,
t=None,
queue=None,
out=None,
check=True,
block=False,
):
"""Compute the flat field wavefield. Returned *out* array is different from the input
one.
"""
if queue is None:
queue = cfg.OPENCL.queue
if out is None:
out = cl_array.Array(queue, shape, dtype=cfg.PRECISION.np_cplx)
ps = make_tuple(pixel_size)
if t is None:
x, y, z = self.trajectory.control_points.simplified.magnitude[0]
else:
x, y, z = self.trajectory.get_point(t).simplified.magnitude
x += offset[1].simplified.magnitude
y += offset[0].simplified.magnitude
center = (x, y, z)
phase = self.phase_profile != "plane"
parabola = self.phase_profile == "parabola"
compute_exponent = exponent or check and phase
self._transfer_real(shape, center, ps, energy, compute_exponent, phase,
parabola, out, queue, block)
if compute_exponent:
if check and phase and not is_wavefield_sampling_ok(out,
queue=queue):
LOG.error("Insufficient beam phase sampling")
if not exponent:
out = clmath.exp(out, queue=queue)
return out
def test_transmission_sampling(self):
def compute_transmission_function(n, ps, energy, material):
wedge = np.tile(np.arange(n), [n, 1]) * ps
wedge = StaticBody(wedge, ps, material=material)
return wedge.transfer((n, n), ps, energy, exponent=True)
def compute_distance(n, ps, lam, ps_per_lam):
ca = (lam / (ps_per_lam * ps)).simplified.magnitude
alpha = np.arccos(ca)
theta = np.pi / 2 - alpha
return (n * ps / (2 * np.tan(theta))).simplified
n = 32
ps = 1 * q.um
energies = np.arange(5, 30) * q.keV
energy = 10 * q.keV
lam = physics.energy_to_wavelength(energy)
# Delta causes phase shift between two adjacent pixels by 2 Pi
delta = (lam / ps).simplified.magnitude
ri = np.ones_like(energies.magnitude, dtype=np.complex) * delta + 0j
material = Material('dummy', ri, energies)
# Single object
u = compute_transmission_function(n, ps, energy, material)
self.assertFalse(physics.is_wavefield_sampling_ok(u))
# 4x supersampling => phase shift Pi/2
u = compute_transmission_function(4 * n, ps / 4, energy, material)
self.assertTrue(physics.is_wavefield_sampling_ok(u))
# 4x supersampling with 2 objects => phase shift Pi
n *= 4
ps /= 4
wedge = np.tile(np.arange(n), [n, 1]) * ps
wedge = StaticBody(wedge, ps, material=material)
u = physics.transfer_many([wedge, wedge], (n, n),
ps,
energy,
exponent=True)
self.assertFalse(physics.is_wavefield_sampling_ok(u))
# X-ray source with a parabolic phase profile
n = 128
ps = 1 * q.um
trajectory = Trajectory([(n / 2, n / 2, 0)] * ps)
# 1 pixel per wavelength => insufficient sampling
d = compute_distance(n, ps, lam, 1)
source = BendingMagnet(2.5 * q.GeV,
150 * q.mA,
1.5 * q.T,
d,
1,
np.array([0.2, 0.8]) * q.mm,
ps,
trajectory,
phase_profile='parabola')
u = source.transfer((n, n), ps, energy, exponent=True)
self.assertFalse(physics.is_wavefield_sampling_ok(u))
# 4 pixel per wavelength => good sampling
d = compute_distance(n, ps, lam, 4)
source = BendingMagnet(2.5 * q.GeV,
150 * q.mA,
1.5 * q.T,
d,
1,
np.array([0.2, 0.8]) * q.mm,
ps,
trajectory,
phase_profile='parabola')
u = source.transfer((n, n), ps, energy, exponent=True)
self.assertTrue(physics.is_wavefield_sampling_ok(u))
def _transfer(self,
shape,
pixel_size,
energy,
offset,
exponent=False,
t=None,
queue=None,
out=None,
check=True,
block=False):
"""Compute the flat field wavefield. Returned *out* array is different from the input one."""
if queue is None:
queue = cfg.OPENCL.queue
ps = make_tuple(pixel_size)
if t is None:
x, y, z = self.trajectory.control_points.simplified.magnitude[0]
else:
x, y, z = self.trajectory.get_point(t).simplified.magnitude
x += offset[1].simplified.magnitude
y += offset[0].simplified.magnitude
center = (x, y, z)
cl_center = gutil.make_vfloat3(*center)
cl_ps = gutil.make_vfloat2(*pixel_size.simplified.magnitude[::-1])
fov = np.arange(0, shape[0]) * ps[0] - y * q.m
angles = np.arctan((fov / self.sample_distance).simplified)
profile = self._create_vertical_profile(energy, angles, ps[0]).rescale(
1 / q.s).magnitude
profile = cl_array.to_device(queue,
profile.astype(cfg.PRECISION.np_float))
if out is None:
out = cl_array.Array(queue, shape, dtype=cfg.PRECISION.np_cplx)
z_sample = self.sample_distance.simplified.magnitude
lam = energy_to_wavelength(energy).simplified.magnitude
phase = self.phase_profile != 'plane'
parabola = self.phase_profile == 'parabola'
if exponent or check and phase:
ev = cfg.OPENCL.programs['physics'].make_flat(
queue, shape[::-1], None, out.data, profile.data, cl_center,
cl_ps, cfg.PRECISION.np_float(z_sample),
cfg.PRECISION.np_float(lam), np.int32(True), np.int32(phase),
np.int32(parabola))
if check and phase and not is_wavefield_sampling_ok(out,
queue=queue):
LOG.error('Insufficient beam phase sampling')
if not exponent:
out = clmath.exp(out, queue=queue)
else:
ev = cfg.OPENCL.programs['physics'].make_flat(
queue, shape[::-1], None,
out.data, profile.data, cl_center, cl_ps,
cfg.PRECISION.np_float(z_sample), cfg.PRECISION.np_float(lam),
np.int32(exponent), np.int32(phase), np.int32(parabola))
if block:
ev.wait()
return out