Array-based scattering calculations

This example demonstrates how to compute far fields, S1/S2 amplitudes and Stokes parameters using arbitrary phi and theta arrays.

import numpy as np
from PyMieSim import (
    ureg,
    Sphere,
    PlaneWave,
    Simulation,
    PolarizationState,
)
import matplotlib.pyplot as plt

Create a simple plane wave source

source = PlaneWave(
    wavelength=632.8 * ureg.nanometer,
    polarization=PolarizationState(angle=0 * ureg.degree),
    amplitude=1 * ureg.volt / ureg.meter,
)

scatterer = Sphere(
    diameter=200 * ureg.nanometer,
    material=1.5,
    medium=1.0,
)

setup = Simulation(
    scatterer=scatterer,
    source=source
)

phi = np.linspace(0, np.pi, 150) * ureg.radian
theta = np.linspace(0, np.pi / 2, 150) * ureg.radian

E_para, E_perp = setup.get_farfields(phi=phi, theta=theta, distance=1 * ureg.meter)

plt.figure(figsize=(10, 5))
plt.subplot(1, 2, 1)
plt.plot(phi, np.abs(E_para), label="E_para")
plt.title("E_para Far Field")
plt.xlabel("Phi (radians)")
plt.ylabel("Magnitude")
plt.legend()
plt.subplot(1, 2, 2)
plt.plot(phi, np.abs(E_perp), label="E_perp", color="orange")
plt.title("E_perp Far Field")
plt.xlabel("Phi (radians)")
plt.ylabel("Magnitude")
plt.legend()
plt.tight_layout()
plt.show()

S1 and S2 scattering amplitudes

S1, S2 = setup.get_s1s2(angles=phi)

plt.figure(figsize=(10, 5))
plt.subplot(1, 2, 1)
plt.plot(phi, np.abs(S1), label="S1")
plt.title("S1 Scattering Amplitude")
plt.xlabel("Phi (radians)")
plt.ylabel("Magnitude")
plt.legend()
plt.subplot(1, 2, 2)
plt.plot(phi, np.abs(S2), label="S2", color="orange")
plt.title("S2 Scattering Amplitude")
plt.xlabel("Phi (radians)")
plt.ylabel("Magnitude")
plt.legend()
plt.tight_layout()
plt.show()

Stokes parameters

I, Q, U, V = setup.get_stokes(phi=phi, theta=theta, distance=1 * ureg.meter )

plt.figure(figsize=(10, 5))
plt.subplot(2, 2, 1)
plt.plot(phi, I, label="I")
plt.title("Stokes I")
plt.xlabel("Phi (radians)")
plt.ylabel("Intensity")
plt.legend()
plt.subplot(2, 2, 2)
plt.plot(phi, Q, label="Q", color="orange")
plt.title("Stokes Q")
plt.xlabel("Phi (radians)")
plt.ylabel("Intensity")
plt.legend()
plt.subplot(2, 2, 3)
plt.plot(phi, U, label="U", color="green")
plt.title("Stokes U")
plt.xlabel("Phi (radians)")
plt.ylabel("Intensity")
plt.legend()
plt.subplot(2, 2, 4)
plt.plot(phi, V, label="V", color="red")
plt.title("Stokes V")
plt.xlabel("Phi (radians)")
plt.ylabel("Intensity")
plt.legend()
plt.tight_layout()
plt.show()