Stokes parameters

1 files changed, 18 insertions, 6 deletions

diff --git a/src/phys.py b/src/phys.py
index 4e78fe2..c47a497 100644
--- a/src/phys.py
+++ b/src/phys.py
@@ -7,6 +7,16 @@ from PyQt5.QtCore import *
 
 from ui import *
 
+
+
+def jones_to_stokes(E):
+	I = np.abs(E[0] ** 2) + np.abs(E[1] ** 2)
+	Q = np.abs(E[0] ** 2) - np.abs(E[1] ** 2)
+	U = 2 * np.real(E[0] * np.conjugate(E[1]))
+	V = 2 * np.imag(E[0] * np.conjugate(E[1]))
+	return np.array([I, Q, U, V])
+
+
 def R(theta):
 	return np.array([[np.cos(theta), np.sin(theta)],
 			 [-np.sin(theta), np.cos(theta)]])
@@ -14,7 +24,6 @@ def R(theta):
 
 class Ellipse:
 	def __init__(self, state):
-		# FIXME: a less brute-force way of doing this
 		if state is None:
 			self.alpha = np.nan
 			self.theta = np.nan
@@ -44,12 +53,14 @@ class Ellipse:
 		      bounds=[0, np.pi], method="bounded")
 		self.a = r(opt.x)
 
-		self.alpha = angle(x(opt.x))
+		V = jones_to_stokes(state)
+
+		self.alpha = np.arctan2(V[2], V[1]) / 2
+		if self.alpha < 0:
+			self.alpha += np.pi
 
-		self.e = self.b / self.a
-		self.theta = np.arctan(self.e)
-		if self.alpha > angle(x(opt.x + 0.001)):
-			self.theta *= -1
+		R = np.sqrt(V[1] ** 2 + V[2] ** 2 + V[3] ** 2) 
+		self.theta = np.arcsin(V[3] / R) / 2
 
 class Polarizer:
 	def __init__(self, type, delta=0):
@@ -98,6 +109,7 @@ class System:
 
 	def recalculate(system):
 		system.states = [None] * len(system.elements)
+		system.Vs = [None] * len(system.elements)
 		system.ellipses = list()
 
 		state = None