Basic example for TOF and q-defined reflectometry

Examples/python/simulation/ex06_Reflectometry/TimeOfFlightReflectometry.py

+"""
+An example of defining reflectometry instrument
+for time of flight experiment. In this example
+two approaches are used: first, we define
+beam parameters through a range of wavelengths and
+an incident angle; second, we will use purely
+qz-defined beam, without explicitly specifying
+incident angle or a wavelength.
+Note that these approaches work with SLD-based
+materials only.
+"""
+import numpy as np
+import bornagain as ba
+from matplotlib import pyplot as plt
+from bornagain import deg, angstrom
+
+inc_angle = 2.0 * deg  # inclination angle
+qzs = np.linspace(0.01, 1.0, 500, dtype=float)  # qz-values
+
+# factor to convert qz values to wavelengths
+norm_factor = 4.0 * np.pi * np.sin(inc_angle)
+wls = np.asarray([norm_factor / qz for qz in qzs])  # wavelength values
+
+
+def get_sample():
+    """
+    Defines sample and returns it. Note that SLD-based materials are used.
+    """
+
+    # creating materials
+    m_ambient = ba.MaterialBySLD("Ambient", 0.0, 0.0)
+    m_ti = ba.MaterialBySLD("Ti", -1.9493e-06, 0.0)
+    m_ni = ba.MaterialBySLD("Ni", 9.4245e-06, 0.0)
+    m_substrate = ba.MaterialBySLD("SiSubstrate", 2.0704e-06, 0.0)
+
+    # creating layers
+    ambient_layer = ba.Layer(m_ambient)
+    ti_layer = ba.Layer(m_ti, 30 * angstrom)
+    ni_layer = ba.Layer(m_ni, 70 * angstrom)
+    substrate_layer = ba.Layer(m_substrate)
+
+    # creating multilayer
+    multi_layer = ba.MultiLayer()
+    multi_layer.addLayer(ambient_layer)
+    for i in range(10):
+        multi_layer.addLayer(ti_layer)
+        multi_layer.addLayer(ni_layer)
+    multi_layer.addLayer(substrate_layer)
+
+    return multi_layer
+
+
+def get_simulation_q():
+    """
+    Defines and returns specular simulation
+    with a qz-defined beam
+    """
+    simulation = ba.SpecularSimulation()
+    simulation.setBeamParameters(qzs)
+    return simulation
+
+
+def get_simulation_wl():
+    """
+    Defines and returns specular simulation
+    with a time-of-flight beam
+    """
+    simulation = ba.SpecularSimulation()
+    simulation.setBeamParameters(wls, inc_angle)
+    return simulation
+
+
+def run_simulation(simulation):
+    """
+    Runs simulation and returns its result.
+    """
+    sample = get_sample()
+    simulation.setSample(sample)
+    simulation.runSimulation()
+    return simulation.result()
+
+
+def plot(result_wl, result_qz):
+    """
+    Plots data for several selected layers
+    """
+
+    ba.plot_simulation_result(result_qz, postpone_show=True)
+
+    wl_sim_data = result_wl.data()
+    wl_axis = wl_sim_data.getAxis(0).getBinCenters()
+    plt.semilogy(wl_axis, result_wl.array(), 'ko', markevery=10)
+    plt.legend([r'$q_z$-defined beam',
+                r'$\lambda$-defined beam'],
+               loc='upper right')
+
+    plt.show()
+
+
+if __name__ == '__main__':
+    result_tof = run_simulation(get_simulation_wl())
+    result_q = run_simulation(get_simulation_q())
+    plot(result_tof, result_q)