It's a good resource but professional grade. I first got into this when I was taking Physics 7C which has a chapter on lenses. There's an approximation they us

It's a good resource but professional grade. I first got into this when I was taking Physics 7C which has a chapter on lenses. There's an approximation they use and I thought couldn't they use ray tracing and do a better job? So I started reading and yeah, they could and they do. What I was wondering about is what free form lenses actually are. And with modern CNC capabilities, you can do a much better job.