adding help text

pykat/optics/fabry_perot.py

-# ------------------------------------------------------
-# Moving some utility function from Simtools
-# http://www.gwoptics.org/simtools/
-# to PyKat. Work in progress, currently these
-# functions are not tested.
-# 
-# Andreas 30.11.2014
-# ------------------------------------------------------
+"""
+------------------------------------------------------
+Utility functions to compute parameters of Fabry
+Perot cavities. Functions based on earlier version
+in Matlab( http://www.gwoptics.org/simtools/)
+Work in progress, currently these functions are
+untested!
+
+Andreas 30.11.2014
+http://www.gwoptics.org/pykat/
+------------------------------------------------------
+"""
 from __future__ import absolute_import
 from __future__ import division
 from __future__ import print_function
@@ -15,6 +19,13 @@ from __future__ import unicode_literals
 import numpy as np
 
 def cavity_info(Lambda, L, Rc1, Rc2):
+	"""
+	Function computes several cavity paramaters
+	Input: Lambda, L (length), Rc1, Rc2 (radii of curvature of cavity mirrors)
+	Output: zr (Rayleigh range), w0 (waist size), z1 (distance waist<->mirror1)
+	        w1, w2 (spot size on both mirrors)
+    See examples/optics/cavity_w_Rc.py for an example usage.
+	"""
 	g1 = 1-L/Rc1
 	g2 = 1-L/Rc2
 	G  = g1*g2
@@ -31,6 +42,11 @@ def cavity_info(Lambda, L, Rc1, Rc2):
 	return [zr, w0, z1, w1, w2]
 	
 def cavity_w1w2_Rc1Rc2(Lambda, L, w1, w2):
+	"""
+	Function computes the radii of curvatures (Rc1, Rc2) for a linear
+	cavity to produce the requested mirror spot sizes (w1,w2) for a given
+	length (L) and wavelength (Lambda).
+	"""
 	C = (Lambda*L/np.pi)**2
 	g1 = -1.0 * np.sqrt(1-C/(w1*w2)**2)*(w2/w1)
 	g2 = -1.0 * np.sqrt(1-C/(w1*w2)**2)*(w1/w2)