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Monday, 20 February 2012

Difference between LED and LASER

Wavelength Content : A monochromatic source consists of radiation of a single wavelength or a very small range of wavelength.LargeSmall (desirable; more monochromatic)
Spectral Width/Line Width : The wavelength interval over which the magnitude of all the spectral components is greater than or equal to a specified fraction of the total magnitude, Here, the fraction is (0.707)*P50 nm< 5 nm
Principle of EmissionSpontaneous; random photon emission (hence, not directional)Stimulated
Coherence : A constant phase difference between two wavesIncoherent; since emission is spontaneousCoherent; since emission is stimulated; same phase as the stimulating photon
Output PowerLowHigh
DirectionalityLowHighly directional
Speed of OperationSlowFaster
Numerical Aperture : determines the output patternHigherLower
Ease of UseEasier to use; less complex circuitryComplex circuitry; needs thermal & optical stabilization circuits due to light amplification

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