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LASERS STEFAN THOMAS


What is a laser?

Light Amplification by Stimulated Emission of Radiation


Theory ď ľ Albert

Einstein, in 1917, theorized that electrons could be stimulated to emit light of a particular wavelength through the process of emitting and absorbing energy


Components of a laser 

Amplifying/Gain Medium 

Can be in solid, liquid, or gas phase

External Energy Source

2 Mirrors/Reflectors


Three Key Processes 

Stimulated Absorption 

Spontaneous Emission 

The electrons of an atom become “excited” and move to a higher energy level by stimulation by an external energy source

Once in the excited state, the electron returns to the ground state, releasing a photon—a particle of light

Stimulated Emission 

When an incident photon strikes an electron that is returning to ground state from the excited state, the emitted photon will be identical to the incident photon (the two photons will have the same frequency, phase, and direction)


Light Amplification


Unique Characteristics 

Monochromatic – waves of a laser are of one wavelength, and thereby one frequency

Coherent – waves of a laser are in phase and in the same direction (polarized)

Collimated – laser beams are very narrow and precise


Applications of lasers 

Medicine 

LASIK

Cosmetic Surgery

Imaging and Diagnosis

Military

Industry

Consumer goods

Lasers presentation  
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