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5. Lasers

5. Lasers. Introduction to Lasers. Laser Acupuncture, Laser Scalpel and Laser W/R Head. Laser Scanner. Lasing Conditions. Theory of Laser. General Optical Resonator and Laser Transverse Mode. Gaussian Beam. Gaussian Beam (Cont’). Laser Longitudinal Mode. Optical resonance:.

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5. Lasers

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  1. 5. Lasers

  2. Introduction to Lasers

  3. Laser Acupuncture, Laser Scalpel and Laser W/R Head

  4. Laser Scanner

  5. Lasing Conditions

  6. Theory of Laser

  7. General Optical Resonator and Laser Transverse Mode

  8. Gaussian Beam

  9. Gaussian Beam (Cont’)

  10. Laser Longitudinal Mode Optical resonance: where λ: wavelength of the resonating frequency, L: length of the cavity, m : an integral Eg. laser diode : cavity length = 300 m; AlGaAs : gap wavelength  800nm How many wavelength will fit into the cavity ?

  11. Multi-(Longitudinal) Mode Laser Cavity resonance frequency Spacing between the adjacent frequency ( frequency spacing ) Wavelength spacing 0: free space value of the wavelength v: velocity of the wave in cavity c : speed of light n : refractive index of cavity material

  12. Eg. Laser diode : cavity length = 300 m refractive index = 3.6 ; line width of the cavity = 2 nm peak radiating wavelength 0 = 800 nm Find output spectrum from the laser frequency spacing: wavelength spacing: mode number:

  13. Typical Planar Laser diode (LD) Structure

  14. Characteristics of Laser Diode

  15. Modulation of Laser Diode

  16. Radiation of Laser Diode Radiation pattern Output spectrum

  17. Typical Characteristics of Diode Light Sources

  18. Laser Safety Rules 1) Wear special goggles 2) Never looking the primary laser beam or into the specular reflection of a beam 3) Higher power beams should be terminated 4) Skin protection should be worn at higher power levels ( e.q. heavy white cloth ) 5) Special precaution for invisible laser beam

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