Fabrication
The fabrication process begins with a digital geometric model
that is converted into a series of slices to be physically fabricated
layer-by-layer. 3D printing of optical quality materials
typically requires a photopolymer-based process. Each layer
is fabricated in sequence by selectively exposing a liquid
photopolymer material to an ultra-violet (UV) light source,
causing the material to cure into a solid state. Traditionally
this has been achieved using ‘stereolithography’, where
a precise laser is traced through a vat of liquid photopolymer.
Other approaches include controlled exposure to UV light
using a projector, or physical deposition of liquid photopolymer
in the presence of a UV light source. The fundamental
process of layer-by-layer fabrication with photopolymer materials
is common throughout each approach.