I'm working on a few projects that require lenses to focus LED light flashes, similar to those lenses used by police lights (TIR lens) and other strobe traffic lighting utilizing Fresnel lenses. I've scoured the internet and cannot find anyone selling just the lenses or any guides on how they are/can be made in custom situations. I've provided a few examples below:
I found an article detailing such traffic light lenses and that currently they are chiefly made out of polycarbonate but not anything further.
I am asking how to create these lenses and or trying to find a place that will allow me to purchase them.