5: Polarization

Example number 5.1, Page number 113

In [5]:
#importing modules
from __future__ import division
import math

#Variable declaration
mew_g = 1.72;    #Refractive index of glass
mew_w = 4/3;      #Refractive index of water

#Calculation
#For polarization to occur on flint glass, tan(i) = mew_g/mew_w
#Solving for i
i_g = math.atan(mew_g/mew_w);      #angle of incidence for complete polarization for flint glass(rad)
a = 180/math.pi;       #conversion factor from radians to degrees
i_g = i_g*a;      #angle of incidence(degrees)
i_g = math.ceil(i_g*10**2)/10**2;     #rounding off the value of i_g to 2 decimals
#For polarization to occur on water, tan(i) = mew_w/mew_g
#Solving for i
i_w = math.atan(mew_w/mew_g);     #angle of incidence for complete polarization for water(rad)
i_w = i_w*a;       #angle of incidence(degrees)
i_w = math.ceil(i_w*10**3)/10**3;     #rounding off the value of i_w to 3 decimals

#Result
print "The angle of incidence for complete polarization to occur on flint glass is",i_g, "degrees"
print "The angle of incidence for complete polarization to occur on water is",i_w, "degrees"
The angle of incidence for complete polarization to occur on flint glass is 52.22 degrees
The angle of incidence for complete polarization to occur on water is 37.783 degrees

Example number 5.2, Page number 113

In [6]:
#importing modules
from __future__ import division
import math

#Variable declaration
I0 = 1;    #For simplicity, we assume the intensity of light falling on the second Nicol prism to be unity(W/m**2)
theta = 30;    #Angle through which the crossed Nicol is rotated(degrees)

#Calculation
theeta = 90-theta;     #angle between the planes of transmission after rotating through 30 degrees
a = math.pi/180;           #conversion factor from degrees to radians
theeta = theeta*a;     ##angle between the planes of transmission(rad)
I = I0*math.cos(theeta)**2;    #Intensity of the emerging light from second Nicol(W/m**2)
T = (I/(2*I0))*100;    #Percentage transmission of incident light
T = math.ceil(T*100)/100;     #rounding off the value of T to 2 decimals

#Result
print "The percentage transmission of incident light after emerging through the Nicol prism is",T, "%"
The percentage transmission of incident light after emerging through the Nicol prism is 12.51 %

Example number 5.3, Page number 113

In [7]:
#importing modules
from __future__ import division
import math

#Variable declaration
lamda = 6000;    #Wavelength of incident light(A)
mew_e = 1.55;    #Refractive index of extraordinary ray
mew_o = 1.54;     #Refractive index of ordinary ray

#Calculation
lamda = lamda*10**-8;      #Wavelength of incident light(cm)
t = lamda/(4*(mew_e-mew_o));    #Thickness of Quarter Wave plate of positive crystal(cm)

#Result
print "The thickness of Quarter Wave plate is",t, "cm"
The thickness of Quarter Wave plate is 0.0015 cm

Example number 5.4, Page number 114

In [8]:
#Calculation
#the thickness of a half wave plate of calcite for wavelength lamda is
#t = lamda/(2*(mew_e - mew_o)) = (2*lamda)/(4*(mew_e - mew_o))

#Result
print "The half wave plate for lamda will behave as a quarter wave plate for 2*lamda for negligible variation of refractive index with wavelength"
The half wave plate for lamda will behave as a quarter wave plate for 2*lamda for negligible variation of refractive index with wavelength

Example number 5.5, Page number 114

In [9]:
#importing modules
from __future__ import division
import math

#Variable declaration
lamda = 500;    #Wavelength of incident light(nm)
mew_e = 1.5508;    #Refractive index of extraordinary ray
mew_o = 1.5418;     #Refractive index of ordinary ray
t = 0.032;     #Thickness of quartz plate(mm)

#Calculation
lamda = lamda*10**-9;     #Wavelength of incident light(m)
t = t*10**-3;     #Thickness of quartz plate(m)
dx = (mew_e - mew_o)*t;    #Path difference between E-ray and O-ray(m)
dphi = (2*math.pi)/lamda*dx;    #Phase retardation for quartz for given wavelength(rad)
dphi = dphi/math.pi;

#Result
print "The phase retardation for quartz for given wavelength is",dphi, "pi rad"
The phase retardation for quartz for given wavelength is 1.152 pi rad

Example number 5.6, Page number 114

In [13]:
#importing modules
import math

#Variable declaration
C = 52;    #Critical angle for total internal reflection(degrees)

#Calculation
a = math.pi/180;           #conversion factor from degrees to radians
C = C*a;      #Critical angle for total internal reflection(rad)
#From Brewster's law, math.tan(i_B) = 1_mew_2
#Also math.sin(C) = 1_mew_2, so that math.tan(i_B) = math.sin(C), solving for i_B
i_B = math.atan(math.sin(C));    #Brewster angle at the boundary(rad)
b = 180/math.pi;           #conversion factor from radians to degrees
i_B = i_B*b;     #Brewster angle at the boundary(degrees)

#Result
print "The Brewster angle at the boundary between two materials is",int(i_B), "degrees"
The Brewster angle at the boundary between two materials is 38 degrees
In [10]: