from math import *
import numpy as np

ne=1.747	# refractive index for extraordinary axis
no=1.754	# refractive index for ordinary axis
d=15e-2	# ITM thickness
lamb=1064e-9	# laser wavelength
Rs=1-0.4996	# BS reflectivity for s-pol
Rp=0.3	# BS reflectivity for p-pol

dlu={"X": 3.47e-9, "Y":4.07e-9}
dls={"X": 25.9e-9, "Y":30.1e-9}

for arm in ["X","Y"]:
	dlb=np.abs(2*dlu[arm]-2*dls[arm])	# optical path length between polarizations
	phi=2*pi*dlb/2/lamb	# polarization rotation per one path
	loss=1-(np.cos(2*phi))**2	# 2 for double pass
	print "power loss in ITM reflection " + arm + ": ", loss
	print "power ratio at POP (p/(s+p)):",
	if arm == "Y":
		print loss*Rp/((1-loss)*Rs+loss*Rp)
	if arm == "X":
		print loss*(1-Rp)/((1-loss)*(1-Rs)+loss*(1-Rp))

rhoth=1000e-6	# loss threshold
dlbth=sqrt(lamb**2*rhoth/(2*pi)**2)
thetath=sqrt(dlbth*ne**2/(d*no*(no**2-ne**2)))/pi*180
print "minimum optical path length between polarizations:", dlbth
print "minimum angle between c-axis and beam axis (deg):", thetath