Laser Physics 1

gain/active/lasing medium

the source of optical gain within a laser (caused by stimulated emission of photons through electronic or molecular transitions)

photon energy

solid angle of laser beam

optical frequencies

spectral purity

where Δf is the bandwidth (range of frequencies present in the beam) and f is the peak frequency

coherence time

the amount of time required for different frequency components of the beam to begin destructively interfering with each other

coherence length

the distance over which the beam propagates during the coherence time (in vacuum for this formula)

spectral intensity

A is the source area

spectral brightness

the spectral intensity per steradian

blackbody formula?