(See Notes on Lasers and Light by D. L. Jaggard)
Beamwidth ~l/D ~ 103 radians
Beamwidth ~p radians
Minimum spot size ~l
Minimum spot size >>l
Wavelength:l = c/f (in free space)
l = wavelength (m)
Laser is brighter than the sun!
Sun brightness 1.5 x 105 lumens/cm2-str.
Laser brightness 108 lumens/cm2-str.
On a per frequency basis, laser is ~ 106 more intense
Solid Angle W
Energy spread over l of < 1Å = 1010 m
Energy spread over l from 4,000 Å - 7,000 Å
|Differential Wavelength/Differential Frequency:
A measure of the ability of a wave to interfere with a delayedor displaced version of itself.
Light can interfere with itself over significant distances (speckle)
Light cannot interfere with itself easily
Coherence length lc coherence time t:
Three components needed:
Source of power (pump)
Amplifier (active medium)
Feedback (cavity or reflector)
1. Divergence-diffraction effect/beam waist