HW2_Q3

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Wed Mar 20 09:56:59 2019

@author: dedu0223
"""

import numpy as np
import matplotlib.pyplot as plt
import miepython
import urllib
import segelstein

lam1 = 0.555*10**-6 #meter
r = 5*10**-6 #meter
x = 2*np.pi*r/lam1
k = 1
url = 'http://www.philiplaven.com/Segelstein.txt'
lam,rfr,rfi = segelstein.segel(url)
lam = np.array(lam) #microns
rfr = np.array(rfr)

idx = np.abs(lam-0.555).argmin()
rfr1 = rfr[idx]
m = rfr1

theta = np.linspace(0,np.pi,200)
mu = np.cos(theta)

[S1,S2] = miepython.mie_S1_S2(m,x,mu)
qext, qsca, qback, g = miepython.mie(m,x)
A = np.pi*r**2
sigma_s = qsca*A
P11 = ((2*np.pi)/(k**2*sigma_s))*(np.abs(S1)**2 + np.abs(S2)**2)

plt.figure()
plt.semilogy(theta, P11)
plt.xlabel('theta')
plt.ylabel('Scattering phase function')
plt.savefig('3.jpg')