Nd (Neodymium) – yag (Yttrium Aluminium Garnet) laser principle Characteristics

Nd (Neodymium) – YAG (Yttrium Aluminium Garnet) LASER Principle Characteristics

• Doped Insulator laser refers to yttrium aluminium garnet doped with neodymium. The Nd ion has many energy levels and due to optical pumping these ions are raised to excited levels. During the transition from the metastable state to E1, the laser beam of wavelength 1.064μm is emitted

Type	:	Doped Insulator Laser
Active Medium	:	Yttrium Aluminium Garnet
Active Centre	:	Neodymium
Pumping Method	:	Optical Pumping
Pumping Source	:	Xenon Flash Pump
Optical Resonator	:	Ends of rods silver coated Two mirrors partially and totally reflecting
Power Output	:	20 kWatts
Nature of Output	:	Pulsed
Wavelength Emitted	:	1.064 μm

Nd (Neodymium) – YAG (Yttrium Aluminium Garnet) LASER

• Power Supply

• Capacitor

• Resistor

• Laser Rod

• Flash Tube

• M1– 100% reflector mirror

• M2 – partial reflector mirror

E1, E2, E3 – Energy levels of Nd E4 – Meta Stable State E0 – ground State Energy Level Applications Transmission of signals over large distances Long haul communication system Endoscopic applications Remaote sensing

• Energy Level Diagram of Nd– YAG LASER

• Non radiative decay

• Laser
• 1.064μm

• Non radiative decay

• E3

• E2

• E0

• E1

• E4

• Nd

Carbon Di Oxide LASER Principle The transition between the rotational and vibrational　energy levels lends to the construction of a molecular gas laser.　Nitrogen atoms are　raised to the excited state which in turn deliver energy to the CO2 atoms whose energy levels are close to it. Transition takes place between the energy levels of CO2 atoms and the laser beam is emitted.

Type	:	Molecular gas laser
Active Medium	:	Mixture of CO2, N2, He or H2O vapour
Active Centre	:	CO2
Pumping Method	:	Electric Discharge Method
Optical Resonator	:	Gold mirror or Si mirror coated with Al
Power Output	:	10 kW
Nature of Output	:	Continuous or pulsed
Wavelength Emitted	:	9.6 μm or 10.6 μm

Symmetric	100	C - stationary O - vibrates simultaneously along molecular axis
Bending	010,020	C & O vibrate perpendicular to molecular axis
Asymmetric Stretching	001, 002	C & O atoms vibrate in opposite directions along molecular axis

Applications

• Applications
• Bloodless surgery
• Open air communication
• Military field

HOMOJUNCTION SEMICONDUCTOR LASER (Ga-As Laser)

• Principle
• The electron in the conduction band combines with a hole in the valence band and the recombination produces radiant energy. This photon induces another electron in the CB to combine with a hole in the VB and thereby stimulate the emission of another photon.

Type	:	Homojunction Semiconductor laser
Active Medium	:	P – N junction
Active Centre	:	Recombination of electrons and holes
Pumping Method	:	Direct Pumping
Optical Resonator	:	Polished junction of diode
Power Output	:	1 mW
Nature of Output	:	Continuous or pulsed
Wavelength Emitted	:	8400 – 8600 Angstrom Units

• Applications
• Compact & used in fibre optic communications
• CD writer
• Relieves pain
• Laser printers

Principle

• Principle
• Two beams (object beam and reference beam) are superimposed on a holographic plate to form an image called a hologram.

Principle

• Principle
• A beam of light (reading beam) having the same wavelength as that of the reference beam used for constructing the hologram, is made to fall over the hologram, which in turn gives rise to a 3-D image in the field of view.