For my AF Assist tool, I decided to make my own optical lenses to focus the light from the IR LED. I experimented with a few lenses I had kicking around (from other flash systems that I took apart) and looked online to see what I could purchase. The lenses I had kicking around did the trick in giving me a direction to follow, but were not prctical for several reasons. Sourcing is a big issue (these are custom lenses) and second they don’t quite fit my application constraints; too big, or need to be too far away from the light source.

After a brief search online (ebay, aliexpress, etc) I decided that I didn’t want to wait a month for some lens that was chosen just on a photo and scant technical info.  It’s too much trial an error for my taste. I’ve always been intimidated by optics. It felt like this black art/science that I knew next to nothing about. Having done some reading, I now feel a little more comfortable attempting to make my own optics.
Besides, learning something new is always great.

I’m approaching this from a couple different angles. 3d printing of a master (and then resin cast using optically clear resin) as well as cnc machining a mold and try to form some acrylic plastic sheet into the shape i want. I don’t quite know which will give better results which is why I’ll take both paths.

Links:
– DIY Plastic lenses
– 3D Printing and CNCing Weird Freeform Lenses
– Bike pump Vacuum pump

A quick CAD sketch for a mold, and then a 3d print resulted in a