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{
"metadata": {
"name": "",
"signature": "sha256:04df0fd624434d43d67fac6cabd770a44e2109835e3a6832f168a8a4e92f27c9"
},
"nbformat": 3,
"nbformat_minor": 0,
"worksheets": [
{
"cells": [
{
"cell_type": "heading",
"level": 1,
"metadata": {},
"source": [
"10: Lasers"
]
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 10.1, Page number 10.6"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"c = 3*10**8 #speed of light(m/sec)\n",
"h = 6.6*10**-34 #planck's constant\n",
"e = 1.6*10**-19\n",
"T = 300 #temperature(K)\n",
"K = 8.61*10**-5\n",
"lamda = 6943 #wavelength, angstrom\n",
"\n",
"#Calculation\n",
"lamda = lamda*10**-10 #wavelength(m)\n",
"#let E2 - E1 be E\n",
"E = h*c/lamda #energy(J)\n",
"E = E/e #energy(eV)\n",
"#let population ratio N2/N1 be N\n",
"N = math.exp(-E/(K*T));\n",
"\n",
"#Result\n",
"print \"relative population of 2 states is\",round(N/1e-30,3),\"*10^-30\"\n",
"print \"answer given in the book is wrong\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"relative population of 2 states is 1.076 *10^-30\n",
"answer given in the book is wrong\n"
]
}
],
"prompt_number": 2
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 10.2, Page number 10.14"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"a2 = 6 #spot diameter(mm)\n",
"a1 = 4 #spot diameter(mm)\n",
"d2 = 2 #distance from laser(m)\n",
"d1 = 1 #distance from laser(m)\n",
"\n",
"#Calculation\n",
"a2 = a2*10**-3 #spot diameter(m)\n",
"a1 = a1*10**-3 #spot diameter(m)\n",
"theta = (a2-a1)/(2*(d2-d1)) #divergence(radian)\n",
"theta = theta*10**3 #divergence(milli radian)\n",
"\n",
"#Result\n",
"print \"divergence is\",theta,\"milli radian\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"divergence is 1.0 milli radian\n"
]
}
],
"prompt_number": 3
},
{
"cell_type": "heading",
"level": 2,
"metadata": {},
"source": [
"Example number 10.3, Page number 10.46"
]
},
{
"cell_type": "code",
"collapsed": false,
"input": [
"#importing modules\n",
"import math\n",
"from __future__ import division\n",
"\n",
"#Variable declaration\n",
"n = 1 #for air\n",
"lamda = 650 #wavelength(nm)\n",
"bs = 1 #beam size(mm)\n",
"fl = 1 #focal length of lens(mm)\n",
"\n",
"#Calculation\n",
"lamda = lamda*10**-9 #wavelength(m)\n",
"bs = bs*10**-3 #beam size(m)\n",
"fl = fl*10**-3 #focal length of lens(m)\n",
"tan_theta = fl/(2*bs) #value of tan_theta\n",
"theta = math.atan(tan_theta)\n",
"NA = n*math.sin(theta)\n",
"NA = math.ceil(NA*10**2)/10**2; #rounding off to 2 decimals\n",
"ss = 0.6*lamda/NA #spot size(m)\n",
"ss = ss*10**6; #spot size(micro metre)\n",
"ss = math.ceil(ss*10**3)/10**3; #rounding off to 4 decimals\n",
"\n",
"#Result\n",
"print \"spot size is\",ss,\"micro metre\""
],
"language": "python",
"metadata": {},
"outputs": [
{
"output_type": "stream",
"stream": "stdout",
"text": [
"spot size is 0.867 micro metre\n"
]
}
],
"prompt_number": 6
}
],
"metadata": {}
}
]
}
|
