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Beam Expander - Proof of Concept {Pic Heavy~ish}


Active member
Aug 22, 2013
A few nights ago I decided to try my hand at making a beam expander. I have a handful of different lenses laying about so I figured I would try my luck. I didn't get any pictures of my first attempts but based on the math I made a 2X expander Friday night. It was vey impressive but since a 532 beam is very thin it still wasn't big enough.

After taking a look at my (limited) collection of lenses and crunching some numbers I came up with what was in theory a 7X beam expander. Here's what I got:

I started with the dot size focused to infinity:

3mm dot expanded 7X should yield a 2.1cm beam! (Just shy of one inch!) Which is convenient because my larger lens is 22mm so the beam should fit within the lens. Here are the 2 lenses:

The smaller lens just happened to be 11mm and fit nicely insideThe Green Angel's heat sink. I used a small vice to hold the second lens.

After getting things set up and getting the focus distance set here are the measurements:

Taken about 10cm from the lens: (Please note my assistant was making dinner so you have to subtract about 3mm from the measurement since I couldn't hold the ruler and camera steady)

Taken 26ft or ~8m from the lens. (This one is fairly accurate because I could use the door to steady everything)

So it's fairly well collimated. But that's not the fun part. So here's what the beam looks like without the expander:

And with:

So with the viability of a DIY beam expander out of the way I plan on making it so you can attach it to a hand held.

So what do you guys (and gals) think?

As always, Thanks for reading!
Last edited:


New member
Jul 4, 2012
Sweet :drool: If you are going to make them, perhaps make it so that the either thread onto an aixiz lens holder, or are press fit over the stock focusing knob!


New member
Oct 13, 2013
We that last picture is great! Very thick and still very visible in the light