http://forums.splutterfish.com/viewtopic.php?t=5332
Well not exacltly laser-beam sim, but I like this way of making such cool effect. Now trying to make this in VRay 
The first question - which light type to use ?
I’ve attempted it with Free Directional but with no luck…
You can get something similar in V-Ray, there was a thread about this, let me find it…
Best regards,
Vlado
I’ve searched already, but with no luck 
Vlado - I remember, you showed us pictures with caustics, similar to what I want. But when DB crashed it seems gone now. Smth. like you told the new version was better and could produce some effects correclty… ad I remeber
Yeah, the thread seems to be gone now. I still have the scenes here, so I will try to upload some of the renderings when I get some time. You can email me if you want to look at how the scenes are set up.
Best regards,
Vlado
you can get similar results with particle systems in conjunction with deflectors. Just set your particle ammount, that it looks like a line. quite flexible and you can adjust them interactive in the viewport.
edit. ok just saw their animation. that´s probabely not possible with particle
systems. but simple setups where you only have on light color should work well !
Ok. Thx!
C ur pm.
BTW - particles are not the solution. I need it to be purely rendered . . .
edit
Want to make some physical tests.
Works with pretty much the exact setup Richard used in Brazil, just have to use regular spots instead of the brazil lights and of course change to vray mats. Could use a little fine tuning but close enough for me 
One more thing, get rid of the “Photons Vi” object…
It seems impossible for me to get direct light caustics to hit te plane all the way, it is either at the begining or at the end, not both.
wooh… freaky, was just playing with similar stuff last night. Talk about timing.
Check out this tut on evermotion. Seems similar
can you share your scene RErender
Pretty much just a direct conversion of the scene here http://forums.splutterfish.com/viewtopic.php?t=5332 let me know if you have any problems setting it up for Vray. If you have Rio you can see just how zboxx set his up. For Vray I did get rid of the “Photons Vi” object not sure what purpose it serves in Brazil but it just gets in the way for Vray. Also lower the caustic subs on the lights from the default, 150 is pretty good for testing.
Just tinkering with it now. As i dont have Brazil i cant know exactly how he set it up. But im basically using the case, mirros and lenses and build up the rest from scratch.
I could download Rio… but CBF 
Let me tinker with it abit longer then i might ask for some help
I re-read the Brazil thread and tried their solution for using direct lights, they work great with square lenses, the round lenses were sharpening the caustics in the z too.
SNAP… was just about to post the same thing… LOL… except i worked out the direct light and square lense myself 8)
Hey, can you post your file… i think i broke something and it just aint working right anymore.
THanks
Da main idea is to stretch direct or spot in z axis
damn it… i cant get it around the last 2 mirrors, it stops on the third last.
Scaling on the Z axis makes no difference, other than lowering the quality of the beam due wasting lots of caustic subdivs. And lowering or raisin ght target points makes a difference but i just cant get past the 3rd last mirror… bloody weird.
I have a nice strong beam, and it hits that mirror and dies.
Yep… only few photons get to the last lens . . . I’m working on it
edit
Increase the glass max refl. depth. For ex. to 12