Chapter14-Lasers

Ex1-pg418

In [1]:
import math
##Example 14.1
##calculation of intensity of laser beam

##given values
P=10*10**-3.;##Power in Watt
d=1.3*10**-3.;##diametre in m
A=math.pi*d**2./4.;##area in m**2


##calculation
I=P/A;
print'%s %.2f %s'%('intensity (in W/m^2) is',I,'');

intensity (in W/m^2) is 7533.96

Ex2-pg418

In [2]:
import math
##Example 14.2
##calculation of intensity of laser beam

##given values
P=1*10**-3.;##Power in Watt
l=6328*10**-10.;##wavelength in m
A=l**2.;##area in m**2


##calculation
I=P/A;
print'%s %.3e %s'%('intensity (in W/m^2) is',I,'');

intensity (in W/m^2) is 2.497e+09

Ex3-pg418

In [3]:
import math
##Example 14.3
##calculation of coherence length,bandwidth and line width

##given values
c=3*10**8.;##velocity of light in m/s
t=.1*10**-9.;##timedivision in s
l=6238*10**-10.;##wavelength in m

##calculation
x=c*t;
print'%s %.2f %s'%('coherence length (in m) is',x,'');
d=1./t;
print'%s %.3e %s'%('bandwidth (in Hz) is',d,'');
y=l**2*d/c;##line width in m
print'%s %.2f %s'%('line width(in armstrong )is',y*10**10,'');

coherence length (in m) is 0.03 
bandwidth (in Hz) is 1.000e+10 
line width(in armstrong )is 0.13

Ex4-pg418

In [2]:
import math
##Example 14.4
##calculation of frequency difference

##given values
c=3*10**8;##velocity of light in m/s
l=.5;##distance in m

##calculation
f=c/(2*l);##in hertz
print'%s %.2f %s'%('frequency difference (in MHz) is',f/10**6,'');

frequency difference (in MHz) is 300.00

Ex5-pg418

In [1]:
import math
##Example 14.5
##calculation of no of cavity modes

##given values
c=3*10**8.;##velocity of light in m/s
n=1.75;##refractive index
l=2*10**-2;##length of ruby rod in m
x=6943*10**-10.;##wavelength in m
y=5.3*10**-10.;##spread of wavelength in m

##calculation
d=c/n/l;
f=c*y/x**2.;
m=f/d;
print'%s %.2f %s'%('no of modes is',m,'');

no of modes is 38.48