Spot Size
The spot size of a beam is the beam diameter in free space. It varies along the length of the beam according to the equation:
𝜔𝑧.= 𝜔0.,-1+,,,𝑧-,𝑧-𝑟...-2..
Where
,𝑧-𝑟.=,𝜋,𝜔-0-2.-,𝑟-2..
And ω0 is the beam diameter at r=0, which is the minimum beam experienced by the beam.
![Spot Size](/sites/default/files/styles/viewport/public/2020-07/6294.jpg.webp?itok=Tc6LrOnc)
Related Terms: Acceptance Angle, Core, Mode Field Diameter (MFD), Numerical Aperture (NA)