Flat-top beams are a light beam with a relatively flat intensity profile -- in contrast to Gaussian beams, for example. They often have a super-Gaussian shape.
Top-Hat / Flat-Top Beam Shaper application notes - Holo Or
Materials, Free Full-Text
Flat-top laser beams: Their uses and benefits
Top-Hat / Flat-Top Beam Shaper application notes - Holo Or
Flat Top Laser Beam - Holo Or
How to design a Gaussian to Top Hat beam shaper – Knowledgebase
Tailoring light with a digital micromirror device - Ren - 2015 - Annalen der Physik - Wiley Online Library
Flat-top laser beams: Their uses and benefits
Why Use a Flat Top Laser Beam?
flat-top beams, explained by RP; top-hat beam, supergaussian, intensity profile, beam shaper
PoloRevBucketSP S/M BEAMS
Flat-top beam, Top hat beam, Super-Gaussian beam