High Speed colliamtor for shows

[andyf97]

Hi Guys,

For a while you saw us doing some cool collimation tricks with laser at events and I had a lot of PMs asking for details.

Our way is quite slow using dmx controlled motion control of focusing optics but today I was thinking of maybe another way that will simplyfy it a bit using peizo devices with a mounted scanner mirror. This idea wont be so perfect as our dmx version but it might be useful.

what we are considering is bouncing the beam off this peizo before it reaches the scanners then applying some high frequency to the peizo and drive this by a dmx signal or even the Z ILDA channel. this will not modify the colliamtion but it will mess up the beam enough to have similar effects and also could maybe give something new to graphics.

Now I have no idea how to go about this and have even less time to try it but will do soon.

any thoughts about it?

Andy

[shrad]

hi!

interesting idea you have! but piezzo might not be the good way to go, as their displacement is really small (unless you give them a credit card to eat, or more likely several)

however, a voice-coil might be the trick, perhaps also in resonant mode, to drive a big charge (projector lens or galvos)

the only problem is that it requires a good part of engineering to be done

[andyf97]

The idea is for small deflection but very high speed, enough to almost fuzz the beam a little and at varying proportions according to the signal.

[shrad]

then perhaps these little round voice coil scanners that were used some years ago?

with piezzo devices I think it would be hard to have more than 0.5mm of displacement

[andyf97]

0.5mm would be easy enough

[mixedgas]

The piezo in "piezo grill lighter" have almost as much extension as the best commercial sticks, so you stack them end to end, or put the mirror on a lever. You really want a "stack" though...

These:
http://www.4thegrill.com/grp20620.html

or these:

http://www.gasproductscompany.com/ga...o-lighter.html

Thorlabs sells a cheap stack with good travel, or you can get a bimorph

Steve

[shrad]

are those piezzo devices really usable in electronic projects? if so you really solve one of my problems

I was looking for a piezzo for a modelocking cavity... I'll investigate the solution

[Pangolin]

Sorry to give you guys the bad news, but before going much further with this idea, you might take a look at US Patent 5,274,492.

It's been a while since I have looked at that one, but if I am not mistaken, what you want to do has been patented.

Best regards,

William Benner

[shrad]

I may be wrong, but if we use a flat mirror glued onto a scavenged piezzo device, that shouldn't interfere with this patent, will it?

[weartronics]

The two common ways of doing this are changing the curvature of a mirror (maintains beam profile), and rapid oscillation as you suggested (simple to implement). Bill is correct, it looks like both of these ideas are already patented for vector display in the US. That particular patent doesn't restrict any commercialisation in Europe, but there may be similar European or "worldwide" patents of course...

Regarding changing the curvature of the mirror, so-called "adaptive optics" using piezoelectric actuators are widely used in industrial lasers to deliberately worsen the divergence while maintaining the beam profile (which is important for marking/cutting lasers). This technique can maintain the focal plane in flying optics systems, where the path length is varying depending on the position of the machine.



Regarding rapid oscillation, some very old LaserDisc players contain an assembly with two mirrors mounted on voice coils which looks like it would be ideal for this purpose. If you only need a few, maybe you can source some of the LaserDisc players, it would be a very cheap way to get the parts. There is a photo of the assembly inset top left.



Best regards,

weartronics