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My RGV is Alive!

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^good idea with the 555 timer, I can never remember that they support time on/time off functions.... but now I just use my arduino for PWM needs :D
I still have to make a spiro with the stuff frostin sent me...
 

Benm

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Somehow i want to get a proper set of galvo's now just to make things work like the video :)

As for the color mixing process: to get that right you would probably need either dpss blue or a blue laser diode. Considering the current expense for either, its not very attractive in terms of cost.

As it is, green seems to be the easiest by far, even running a 250 mw red next to a 50 mw green makes the green 'too strong' to mix to proper yellow (or white with blu(ray) added).

I'm still considering making the red part a dual-LOC with a cube combiner for that matter - long term project ;)
 
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^good idea with the 555 timer, I can never remember that they support time on/time off functions.... but now I just use my arduino for PWM needs :D
I still have to make a spiro with the stuff frostin sent me...
I prefer analog. Pulses are nasty when the beam is scanned.
 
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I prefer analog. Pulses are nasty when the beam is scanned.
you can't analog modulate a laser reliably, I don't think. If you set it up right, or use a fast enough PWM, there should be no hint of skipping or anything. And if you have a use for something that requires analog modulation, just put a small capacitor on the PWM output.
 

Benm

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Well, the (real) blue laser diodes -are- coming, though i don't dare to say when they will be available at reasonable cost. Considering the price of blue dpss they don't have to come that cheap to make a viable alternative though.

As for PWM versus analog: The PWM has to be damn fast not to be noticeable when scanning, and you need constant current drivers that can handle that too. Everything based on LM317's and such is definitely a problem there.

The advantage of PWM is mainly in linearity: With diode lasers the output is somewhat proportional to the current (minus the treshold), but for dpss systems this relationship is often very far from linear. With PWM you can expect proper linear modulation from 1% to 100% power easily, if things are thermally stable.
 
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@Benm
in the thread about the aaxa or axaa or whatever laser projector, didn't we learn that it uses a 473nm blue diode? I sent them an email asking, just to be sure. It also uses a 532nm quantum dot laser, and some MEMS chips, not to mention other optics for beam combining and stuff. For all those optics and lasers, $600 seems like a good price. Laser TVs should drive down the price real soon.

And about PWM, how fast do you figure it needs to be to avoid skipping? I like to test the PWM on all my lights with a fan, if the PWM is below a few khz it should cause a stroboscopic effect that seems to affect the fan speed, I'm sure the same effect could be observed on a laser.
 

Trevor

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That build is absolutely brilliant. If anything makes me want to build a while laser, it's that. :eek:

-Trevor
 

Dawinzi

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I just seen your Video and i am still not sure if i´m awake or just daydreaming.
You are my Lasergod.
 

ludwigfan

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I wonder if you can combine three 1W (blue) lasers and get one 3W beam out of it like the OP did here with RGV?
 

ludwigfan

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There's no way to "combine" more than two beams of the same color like you would combine different colors.
Thanks for answering my question. Is that because they are all the same wavelength? And they will destructively interfere? I'm new to this stuff so I don't know how the beams are combined into 1.

Is there a thread or article that explains how the beams are combined in 2 of same wavelength or 3 of differing wavelengths?

Also I assume "combined" is probably not the right word for it, so what is?

Thanks. :thanks:
 
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Thanks for answering my question. Is that because they are all the same wavelength? And they will destructively interfere? I'm new to this stuff so I don't know how the beams are combined into 1.

Is there a thread or article that explains how the beams are combined in 2 of same wavelength or 3 of differing wavelengths?

Also I assume "combined" is probably not the right word for it, so what is?

Thanks. :thanks:
Yes-it's easy to combine lasers of different wavelengths. You simply take a mirror that reflects some colors of light and lets others pass through, and then you line up the lasers so that one gets reflected off the mirror at a 90º angle, and the other one passes through the mirror into the reflected beam. You can get mirrors that pass or reflect multiple colors.

Now there is a way to combine two laser beams of the same wavelength, and that is because lasers are polarized. An easy (but not totally correct) way to think of this is that the "wave" motion of a photon, like this:

is constrained to a two dimensional plane. A polarized mirror is like a venetian blind, like this:

If the wave is vertical, the photon will slip through the venetian blind's slats and make it through. If the wave is horizontal, it will bounce off the venetian blind because it has no way to slip through. If the wave is at a 45º angle, exactly half the photons will slip through. So basically, you take two lasers of the same wavelength and point them at a polarized mirror like you pointed the two different color lasers at a dichroic mirror, and you rotate one of them so that the beam is polarized in a different direction than the first laser. One bounces off, while the other passes through. And "combined" is the right word. I suppose you do have to worry about destructive interference in the beam, but once the photons hit something they go all over the place and interference is not really a problem.
 

Morgan

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There is also a technique known as, 'Knife edging', that can combine more than two beams. It doesn't overlay the beams of different wavelengths, in the same way as a dichroic mirror, or 2 beams of similar wavelength, in the same way a polarizing beam splitter cube would, (as described above). It stacks the beams next to each other. This ends with a much fatter beam but it is a way to get higher powers. I think I'm right in saying that the power density of a beam with good divergence using knife edging would be the same as any one of the beams in that combination.

M
:)
 

ludwigfan

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Great info, thanks guys. This place is awesome for learning stuff, lots of knowledgeable people on here it seems. I'm a Wicked Lasers Arctic III Epic disaster refugee lol. After 2 months of waiting I canceled and waved goodbye to that mess for good.

Now I'm tempted to try my hand at a PBS cube setup. I'd like to try two 1 Watt 445 nm lasers and combine them into one 2W beam. One problem is my Lasercheck power meter only goes to 1W max! Course I bought that thing when 1 Watt seemed absurdly huge and unreachable! lol
 




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