Updated documentation, descriptions for v1.0 release.

scripts/ADCsteps.py

@@ -0,0 +1,87 @@
+#!/usr/bin/env Python3
+import numpy as np
+from AstroAtmosphere import *
+import matplotlib.pyplot as plt
+
+'''
+@ Author:		Joost van den Born 
+@ Contact:		born@astron.nl
+@ Description:	This script uses the equations of the paper to calculate the 
+				residual dispersion due to the finite step size of the ADC.
+'''
+
+
+def angleFunc(x, a):
+	'''
+		Function to fit the ideal angle on
+	'''
+	return np.arccos(a * np.tan(np.deg2rad(x))) * 180/np.pi
+
+
+def angleFuncDeriv(x, a):
+	return (a * (1+np.tan(np.deg2rad(x))**2)) / np.sqrt(1 - a**2 * np.tan(np.deg2rad(x))**2)
+
+
+def cassiniDispersionDeriv(n1, n2, zenith, alpha):
+	a1 = n1 * alpha * np.cos(np.deg2rad(zenith)) / np.sqrt(1 - n1**2 * alpha**2 * np.sin(np.deg2rad(zenith))**2)
+	a2 = n2 * alpha * np.cos(np.deg2rad(zenith)) / np.sqrt(1 - n2**2 * alpha**2 * np.sin(np.deg2rad(zenith))**2)
+	return a1 - a2
+
+
+# Parameters at Cerro Armazones
+T   = 279.65 	# k
+P   = 71200  	# Pa
+H   = 0.22
+xc  = 450   	# ppm
+lat = -24.5983 	# degrees
+h   = 3064  	# m
+l1  = 1.49 		# micron
+l2  = 1.78 		# micron
+zenith = 30 	# degrees
+
+
+
+at = dispersion(lat, h)
+at.setReducedHeight(P, at.rho(P, T, H, xc))
+
+n1 = at.n_tph(l1, T, P, H, xc)
+n2 = at.n_tph(l2, T, P, H, xc)
+
+alpha = at.rc / (at.rc+at.h)
+# c_fH = 0.499413 # From Zemax
+c_fH = 0.46816061517198737 # Completely analytical cf
+# f_fH = 0.46462883308144837 # Best fit to analytical ADC model
+
+
+dispersion 		= at.cassini(n1, n2, zenith)*3.6e6
+dispersionDeriv = cassiniDispersionDeriv(n1, n2, zenith, alpha)*3.6e6
+optAngle 		= angleFunc(zenith, c_fH)
+optAngleDeriv	= angleFuncDeriv(zenith, c_fH)
+maxDev 			= optAngleDeriv / dispersionDeriv
+print('Zenith = %s degrees' %zenith)
+print('Dispersion in mas: ', dispersion)
+print('Dispersion/degree zenith at z=%s: %s mas/degree z' %(zenith, dispersionDeriv))
+print('Optimum angle ADC: %s' %(optAngle))
+print('Optimum angle ADC/degree zenith at z=%s: %s' %(zenith, optAngleDeriv))
+print('Max deviation per mas dispersion: %s degrees' %(maxDev))
+print('At designed stepsize at most %s mas of residual dispersion' %(1/maxDev*(360/1262.5)))
+
+
+# Plotting as a function of zenith angle
+dataList = []
+for zenith in np.linspace(5,65,100):
+	dispersion 		= at.cassini(n1, n2, zenith)*3.6e6
+	dispersionDeriv = cassiniDispersionDeriv(n1, n2, zenith, alpha)*3.6e6
+	optAngle 		= angleFunc(zenith, c_fH)
+	optAngleDeriv	= angleFuncDeriv(zenith, c_fH)
+	maxDev 			= optAngleDeriv / dispersionDeriv
+	dataList.append(1/maxDev*(360/1262.5))
+
+
+fig = plt.figure()
+ax = fig.add_subplot(111)
+ax.plot(np.linspace(5,65,100), dataList)
+ax.grid(True, alpha=0.2)
+ax.set_xlabel('Zenith (degrees)')
+ax.set_ylabel('Residual dispersion (mas)')
+plt.show()