Producing spots by refocussing multimode fiber collimators

Producing spots by refocussing multimode fiber collimators

Spot diameter for refocussing a multimode fiber collimator

{!{!{\emptyset_{spot}=\emptyset_{beam}\cdot\left(\frac{A}{f\prime}-1\right)}!}!}
Øspot: Beam diameter in focus
Øbeam: Collimated beam diameter of a multimode fiber

A: Working distance
f’: Focal length of collimating lens