Laser System: He-Ne laser

Laser System
درسنا في المحاضرات السابقة فكرة عمل الليزر بشكل عام مع التركيز على العوامل المؤثرة
على الليزر. والآن سوف نخصص دراستنا على عدة أنظمة لليزر تختلف باختلاف المادة
ويمكن تقسيم أنظمة الليزر إلى خمسة أقسام ھي على النحو التالي:- Active medium
• The state of matter of the active medium: solid, liquid, gas,
or plasma.
• The spectral range of the laser wavelength: visible
spectrum, Infra-Red (IR) spectrum, etc.
• The excitation (pumping) method of the active medium:
Optic pumping, Electric pumping, etc.
• The characteristics of the radiation emitted from the
laser.
• The number of energy levels which participate in the
lasing process.
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Physics Academy
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والذي Active medium سوف نعتمد على النوع الأول والذي يقسم الليزر حسب المادة
يحدد الخواص التالية:
• Laser Wavelength.
• Preferred pumping method.
• Order of magnitude of the laser output.
• The efficiency of the laser system.
We saw that the two basic requirements for laser action are:
• Population Inversion between the upper and lower laser energy
levels.
• The active medium must be transparent to the output
wavelength.
ھي التي تحدد خواص الليزر ولھذا السبب active medium تجدر الإشارة ھنا إلى أن
تعود تسمية الليزر حسب المادة المستخدمة.
Physics Academy
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Laser types
[1] Gas lasers:
Atom Gas:
• Helium-Neon Laser (He-Ne).
• Metal Vapor Laser (Copper, Gold).
• Helium Cadmium Laser (He-Cd).
•
Ion Gas:
• Argon Ion Laser (Ar+).
• Krypton Laser (Kr+).
•
Molecular Gas:
• Carbon Dioxide Laser (CO2).
• Nitrogen Laser (N2).
• Excimer Laser.
• Chemical Laser.
• Far Infra-Red Laser (FIR).
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[2] Solid State lasers:
• Ruby Laser.
• Neodimium YAG and Nd Glass Laser.
• Color Center Laser.
• Titanium Sapphire Laser.
•
[3] Diode Laser (Semiconductor Laser, Injection Laser).
[4] Dye Laser (Liquid).
[5] Special Lasers:
• Free Electron Laser (FEL).
• X Ray Laser.
Physics Academy
WAVELENGTHS OF MOST COMMON LASERS
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Argon fluoride (Excimer-UV)
Krypton chloride (Excimer-UV)
Krypton fluoride (Excimer-UV)
Xenon chloride (Excimer-UV)
Xenon fluoride (Excimer-UV)
Helium cadmium (UV)
Nitrogen (UV)
Helium cadmium (violet)
Krypton (blue)
Argon (blue)
Copper vapor (green)
Argon (green)
Krypton (green)
Frequency doubled
Nd YAG (green)
Helium neon (green)
Krypton (yellow)
Copper vapor (yellow)
0.193
0.222
0.248
0.308
0.351
0.325
0.337
0.441
0.476
0.488
0.510
0.514
0.528
0.532
0.543
0.568
0.570
Helium neon (yellow)
Helium neon (orange)
Gold vapor (red)
Helium neon (red)
Krypton (red)
Rohodamine 6G dye (tunable)
Ruby (CrAlO3) (red)
Gallium arsenide (diode-NIR)
Nd:YAG (NIR)
Helium neon (NIR)
Erbium (NIR)
Helium neon (NIR)
Hydrogen fluoride (NIR)
Carbon dioxide (FIR)
Carbon dioxide (FIR)
0.594
0.610
0.627
0.633
0.647
0.570-0.650
0.694
0.840
1.064
1.15
1.504
3.39
2.70
9.6
10.6
Key: UV = ultraviolet (0.200-0.400 ?m)
VIS = visible (0.400-0.700 ?m)
NIR = near infrared (0.700-1.400 ?m)
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Helium-Neon (He-Ne) Laser
The Helium-Neon laser was the most common laser
until the spread of diode lasers.
It was first built in 1961 by Ali Javan. The active
medium is a noble gas Neon (Ne), and it is a 4 level
laser.
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• Two meta-stable energy levels act as upper laser levels.
• The He-Ne laser have two lower laser levels, so quite a few
wavelengths can come out of the transitions between these
levels.
• The important wavelengths are:
?1= (632.8 nm), ?2=1.152 ? m, ?3=3.3913 ? m
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