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#!/usr/bin/env python3
# /// script
# requires-python = ">=3.10"
# dependencies = ["bornagain>=25,<26"]
# ///
"""
Intensity vs angle at fixed depth z=100nm (upper vacuum boundary).
"""
import bornagain as ba
ba.require_versions("bornagain>=25,<26")
from bornagain import deg, nm
# beam data
ai_min = 0*deg
ai_max = 1*deg
wl = 0.03*nm # wavelength
# fixed depth at upper boundary
z_fixed = 100*nm
def get_sample():
# Define materials
vac_color = (0.90, 0.93, 0.97)
vac_mat = ba.RefractiveMaterial("Vac", vac_color, 0, 0)
a_color = (0.05, 0.62, 0.55)
a_mat = ba.RefractiveMaterial("A", a_color, 1e-5, 3e-6)
# Define layers
layer_top = ba.Layer(vac_mat)
layer_1 = ba.Layer(a_mat, 300*nm)
layer_bot = ba.Layer(vac_mat)
# Define sample
sample = ba.Sample()
sample.addLayer(layer_top)
sample.addLayer(layer_1)
sample.addLayer(layer_bot)
return sample
def get_simulation(sample):
"""
Returns a depth-probe simulation scanning over angles at fixed depth.
"""
nz = 1 # Single depth point
na = 500
scan = ba.AlphaScan(na, ai_min, ai_max)
scan.setWavelength(wl)
footprint = ba.FootprintSquare(0.01)
scan.setFootprint(footprint)
z_axis = ba.EquiDivision("z (nm)", nz, z_fixed, z_fixed)
simulation = ba.DepthprobeSimulation(scan, sample, z_axis)
return simulation
if __name__ == '__main__':
sample = get_sample()
simulation = get_simulation(sample)
result = simulation.simulate()
ba.showSample3D(sample, sample_size=500*nm, seed=0)
import numpy as np
# Extract 1D data
intensity = result.intensities().flatten()
alpha_axis = result.axis(0)
alpha_values = np.linspace(alpha_axis.min(), alpha_axis.max(),
alpha_axis.size()) / deg
# Custom plot for intensity vs angle
ba.plt.figure(figsize=(10, 6))
ax = ba.plt.gca()
ax.plot(alpha_values, intensity, 'b-', linewidth=2,
label=f'z = {z_fixed/nm:.0f} nm')
ax.axhline(y=1, color='r', linestyle='--', linewidth=1,
label='Expected vacuum intensity')
# Calculate and mark critical angle
delta = 1e-5
theta_c = np.sqrt(2*delta) * 180/np.pi # in degrees
ax.axvline(x=theta_c, color='orange', linestyle=':', linewidth=1.5,
label=f'Critical angle θc = {theta_c:.3f}°')
ax.set_xlabel('Incident angle αi (°)', fontsize=14)
ax.set_ylabel('Intensity', fontsize=14)
title = f'Intensity vs Angle at z = {z_fixed/nm:.0f} nm (upper boundary)'
ax.set_title(title, fontsize=16)
ax.grid(True, alpha=0.3)
ax.legend(fontsize=10)
ax.set_ylim([0, max(intensity)*1.1])
ba.plt.tight_layout()
ba.plt.show()
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