4. Infrared
Visible Light
Ultraviolet
X-rays
Gamma Rays

5. Radio Light
Microwaves
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6. The Visible Spectrum
400nm nm nm nm
Wavelength means
COLOR

7. Speed, Wavelength, Frequency
c =  f

8. Properties of Light Speed (c) Wavelength () Frequency (f)
Nothing travels faster
Absolute constant
Wavelength ()
Gamma rays, X-rays, UV, Visible, IR, Radio
In visible wavelength means color
Frequency (f)
Number of complete waves per second
Energy of a Photon (E)
E = hf

19. Light Amplification by Stimulated Emission of Radiation

20. Spontaneous Emission
Energy
Levels
Photon

21. Stimulated Emission and Absorption

22. Population inversion

25. Some lasers in medical use
CO micron
Er:YAG miron
Ho:YAG 2.1 micron
Nd:YAG nm
Ar 488/514 nm
Kr nm
Cu vapour 511/578 nm
Dye eg 630/675 nm
Diode eg 600 / 905 nm
Excimer > 350 nm

26. Boxes

27. Laser/Tissue interaction
Absorption
Scatter
Refraction