# Encoding: utf-8
import pandas as pd
import numpy as np
import scipy.constants as sc
from numpy.lib.scimath import sqrt
[docs]def calcPseudoDiel(rho, angle: float, output: str = 'eps') -> pd.DataFrame:
"""Calculates the pseudo dielectric function of a measurement from rho.
Args:
rho (pandas.DataFrame): Measurement DataFrame containing rho as complex number as column and wavelength as index
angle (float): Angle of measurement in degree
output (str, optional): Output format for dielectric function.
'n': refractive index,
'eps': Dielectic function as two-column pandas.DataFrame,
'epsi': Dielectric function as imaginary number.
Defaults to 'eps'.
Returns:
pandas.DataFrame: Frame containing the pseudo dielectric function or refractive index.
"""
theta = angle * np.pi / 180
eps = np.sin(theta)**2 * (1 + np.tan(theta)**2 * ((1 - rho) / (1 + rho))**2)
if output == 'n':
n = sqrt(eps)
return pd.DataFrame({'n': n.real,
'k': n.imag}, index=eps.index)
if output == 'epsi':
return eps
return pd.concat({'ϵ1': eps.apply(lambda x: x.real),
'ϵ2': eps.apply(lambda x: x.imag)}, axis=1)
[docs]def calc_rho(psi_delta: pd.DataFrame) -> pd.DataFrame:
"""Calculate rho from a Psi-Delta DataFrame. The Psi-Delta DataFrame should be structured as follows:
index: Wavelength
column 'Ψ': Psi from measurement
column 'Δ': Delta from measurement
This format is as returned from SpectraRay.read_psi_delta_file(...).
Args:
psi_delta (pandas.DataFrame): DataFrame containing Psi+Delta Measurement data
Returns:
pandas.DataFrame: Frame containing rho as an imaginary number.
"""
return psi_delta.apply(lambda x: np.tan(np.deg2rad(x['Ψ'])) *
np.exp(-1j * np.deg2rad(x['Δ'])),
axis=1)
[docs]def get_qwp_thickness(material: "Material", lbda: float) -> float:
"""Return the thickness of a material in nm for a quater wave plate at wavelength 'lbda'.
Args:
material (Material): Material object of the quarter wave plate
lbda (float): Wavelength (in nm) at which the quarter wave plate is calculated
Returns:
float: Thickness (in nm) of quarter wave plate
"""
nr = np.real(material.get_refractive_index(lbda)[0, 0, 0])
return lbda / (4.*nr)