LASER PRINCIPLESDr. Prathyusha PG ENTNarayana Medical College, Nellore

DEFINITION It is an intense beam of coherent monochromatic light (or other electromagnetic radiation) by stimulated emission of photons from excited atoms or molecules

light amplification by stimulated emission of radiation. 

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CONFUSION????!!!!!!

BEFORE WE GO DEEPEEER

KNOW THESE TERMS…..• Absorption

• Emission

• Population inversion

• Stimulated emission

ABSORPTION AND EMISSION

VIDEO

PRINCIPLES AND WORKING OF A LASER _PART 1 - YouTube (480p).mp4

PRINCIPLES AND WORKING OF A LASER _PART 2 - YouTube (480p).mp4

DIFFERENCE BETWEEN SPONTANEOUS AND STIMULATED EMISSIONS

Spontaneous emission Stimulated emission

Spontaneous process and automatically produced

Induced by external radiation

No need of population inversion Requires population inversion

Photons produced are of different energy levels hence incoherent

Same energy levels hence coherent

Photons emitted travel randomly in any direction

Travels in the same direction as the incident photon

SPECTRUM OF ELECTROMAGNETIC RADIATION

CHARACTERISTICS OF LASER RADIATION - YouTube (480p).mp4

CHARACTERISTICS OF LASER

CHARACTERISTICS OF LASER RADIATION - 2 - YouTube (480p).mp4

EFFECT OF LASER BEAM ON THE TISSUES

ZONES OF TISSUE DESTRUCTION

EFFECTS OF LASER• Photo thermal

• Photo acoustic

• Photochemical

• Photodissociation

INVISIBLE LASERS • UV zone

• Infrared

• Micro infrared

VISIBLE LASERS• Different colours

• Argon blue

• KTP laser blue-green color

OPERATIONAL PARAMETERS• Wave length of the laser

• Power

• Exposure time

• Spot size

• Power density

MODES OF DELIVERY• Continous mode

• Pulsed mode

• Q switched mode

DISADVANTAGES OF LASER• High cost

• Special training

• Hazards

• Special anaesthesia

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