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Polygon mirrors?

Skauber

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Hi!

I'm doing a spirograph project with red and green lasers. One of my design ideas is to have a 4, 5 or 6 sided polygon mirror on a motor in order to be able to create a line (and liquid sky effect if I add a fogging machine). But I'm having a bit of trouble finding this type of mirrors, I've looked for barcode scanner parts and such, but no luck. Found one type, but it was very flat, so not big enough.

Where do I buy mirrors like this?
 



diachi

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Hi!

I'm doing a spirograph project with red and green lasers. One of my design ideas is to have a 4, 5 or 6 sided polygon mirror on a motor in order to be able to create a line (and liquid sky effect if I add a fogging machine). But I'm having a bit of trouble finding this type of mirrors, I've looked for barcode scanner parts and such, but no luck. Found one type, but it was very flat, so not big enough.

Where do I buy mirrors like this?

Laser printers have them, find an old laser printer and tear it apart. :beer:

That or try eBay? Maybe take a look at Meredith Instruments, I seem to recall them having some.
 

Skauber

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Not much to find of that here in the Philippines, people wants an arm and a leg even for used ones. Broken ones are very hard to find, and a search on ebay didn't do much. The only ones that pop up are the fairly flat ones, which makes sense since they only need to scan the beam in a thin flat line. I'm adding this as the last mirror on the laser show projector, so it will have to be a taller mirror, perhaps 20 mm or an inch tall or so.
 

Skauber

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Idea: Could it be easier to just use a single galvonometer on the output and hook it up to a sinus wave frequency generator?
 

Alaskan

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Might be something you can make with a set of flat mirrors and something cut to glue them on to. I find them from time to time on ebay, have purchased a few and haven't even used them. I'd help out, but they are in Alaska buried in my junk and I am on the other side of the planet.
 

Skauber

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Would be next to impossible to make one of these and have the mirrors line up correctly to create one single coherent line. :) I did think about buying mirror pieces and do this, but can't think of a way to align them perfectly. The only other way is to use a single mirror on an oscillating galvonometer.
 

Alaskan

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How wide do the mirrors need to be?
 

Skauber

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More or less 20-25 mm, or an inch tall? The diameter isn't important, but not too big. The mirrors I'm using in the spirograph are dental mouth mirrors which are about 22 mm in diameter, so that gives an idea of the project I guess. My idea would be to bounce the output pattern from the spirograph out via the polygon mirror, which would allow me to spin it for a line effect, or rotate it slowly for panning the spirograph pattern sideways. Would use a relatively low speed DC motor, ~500 rpm or so, then control it via PWM.
 

Benm

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Old laser printers (go *****ter/trashheap diving) can be a good source, though they might be a bit bigger than you wish.

Alternatively just getting a set of galvo's and drive them to get the desired output pattern would work fine and be more compact, though not free of charge. The cheapest set could problably do what you wanted with those mirrors and much more and set you back only $100 or so.
 

Skauber

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I really wish I could go dum*psterdiving and find laser printers here. I did a lot of that back in Norway and found lots of cool stuff, but here in Philippines you'll only find garbage, nothing useful. My only option is to buy something, a galvo set could be cool, I see a set for X and Y is 100 bucks on ebay and aliexpress, not sure how good or bad those are, but would be cool if I could buy only one for one axis, my plan for now would be to simply feed it a pure sine wave from a frequency generator to make it pan sideways back and forth. I haven't done too much research into galvos yet, but it is a future project idea when I'm done with the spirograph.
 

Alaskan

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One mans garbage, another mans treasure. Philipines, on average, are not wealthy so nothing of any value goes to waste.
 

Skauber

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That is very true. Once it ends up in the landfill, it really is truly garbage. Anything you are throwing out is picked apart and separated, then sold for the materials and such
 

Benm

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Yeah, that's a bit of an issue in developing countries - if something is in the trash it probably is actually worthless... though a broken laser printer would still contain the parts you need if something else failed on it.

In the west this i quite different, and things found in the trash often still work pretty well, you can grab an older model flatscreen tv from the trash it it'll actually work as long as the trash hasn't been sitting in the rain or been roughly transported.

Printers are expecially good targets for this: Due to the business model, in many cases replacing the toner is about as (or even more!) expensive than buying a new printer, especially in the domestic color ones. For my printer this is true, if i replace all 4 cartridges with brand name ones it would be cheaper to get a whole new printer.

So yeah, i'll replace the black, and then probably discard the entire unit. Sicne i'm into electronics i may strip some components from it, but most people will just dump the entire thing, in working condition, just out of toner. It is as idiotic as leaving a car on the side of the road because it's out of fuel, but a sad realisty for too many products.
 

Skauber

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Broken laser printers don't even make it to the dum*p... :) They get picked apart and sold for parts and scrap metal, so nothing is left for the dum*p....

I guess I can post a thread in the B/S/T section to see if someone has something for sale.. :)
 

Bionic-Badger

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Surplus shed used to have them, but not anymore. I think I bought a few, but didn't put them to any use (they're not at my current location, so I can't sell/ship you one). The mirror surface on them is fairly narrow, about 2-3 mm wide, so kind of hard to keep a good beam on it without some cut-off.

Maybe you could order these? The shipping might be a bit much, but you get 3x.
 

Skauber

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Those are an option, looks like about 1 inch sides on the mirrors. I've posted a thread in the B/S/T section as well, this thread.

I only need one, so I'll see if anything turns up in that thread. If not, then I might jump on those from ebay.
 




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