Laser beam control

[Dr_Doggy]

OK, so i have a laser beam and i am going to spread it vertically, is there a device like a lens or something i can electrically control it, i know the typical trick is rotating motors & mirrors, but i want something faster,

even if i could wrap a wire around the lens and pulse it like a speaker,
or what about a lens that will darken or reflect when charged?

the basic plan is to have my vertical line on the wall, but i want to turn on and off bits on the line on the wall, it needs to be fast though, i want to plot these bits entirely in a 10khz pulse, thats the whole line in 0.0001 seconds,

any suggestion is great@!

 

[Brevor]

Laser scanners use a six sided mirror rotated by a motor to make the scan line.
Try searching on Ebay or somewhere for a surplus scanner like the ones used in the checkout lines in stores.

 

[Dr_Doggy]

ya, something like that , but it needs to do faster "scans" , i need it to do a full sweep within that 0.0001s

 

[Sceadwian]

doggy__ faceted mirrors will do that just fine, you can go nearly as high as you want with the scan rate, if you design it properly but you'll have problem with the laser brightness the faster you go.

 

[crutschow]

doggy__ faceted mirrors will do that just fine, you can go nearly as high as you want with the scan rate, if you design it properly but you'll have problem with the laser brightness the faster you go.

A 10kHz scan rate with a 6-sided mirror would require 100,000rpm, which is not practical. So the op is probably right that he needs some electronic means to scan it.

How about reflecting the beam off a small mirror or aluminum tape on a small cone tweeter. You should be able to drive that at 10kHz. Of course that would tend to give a sinusoidal sweep, since speakers don't do square waves well. Does the sweep need to be linear? But the 10kHz tone from that could be fairly loud and annoying for reasonable values of beam deviation.

 

[Sceadwian]

Thanks crut, didn't do the math, that would be problematic with spinning mirrors. But it will definitely be non linear with magnetics and will require signal modification to cope, you can't design the physical non-linearity out of it so you have to compensate. You could add more mirror sides to the polygonal mirror but that becomes mechanically VERY precise.

 

[Dr_Doggy]

ya, you mean like a compression at the edge, np, if i keep my img at the center, did i mention i want to go up to 800bits,?

I like that speaker idea, how fast could one of those go? I keep thinking if i "make my own" speaker i can do like a "super tweeter" with a low induction it can hit a higher frequency right>? How fast could we go before I'd loose my angles of reflection?

 

[crutschow]

Certainly you can buy small cone tweeters that go above 15KHz, but the amount of cone movement is small, even for high sound levels. That might be sufficient if you have the laser close to the speaker and have the speaker a much larger distance from the wall.

 

[misterT]

A galvanometer (or a "mirror galvanometer") would be a good solution, but might be difficult to build and get to work. And expensive to buy.

**broken link removed**

 

[ModemHead]

The head actuator from a hard disk drive comes to mind, but it may have too much mass to move that fast...

 

[Torben]

This may be overkill or too expensive: **broken link removed** . . .but it would probably do the trick. If you need something simpler, maybe they'd be willing to give you some pointers on how to find something more like what you're after.


Good luck,

Torben

 

[crutschow]

The head actuator from a hard disk drive comes to mind, but it may have too much mass to move that fast...

Hard drives take several ms for the head to move to a new position, which implies a maximum frequency well under a kHz.

 

[Sceadwian]

The high RPM required is doable if the mirror is quiet tiny, finding a motor that can spin that fast would be the hard part.