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Hello Vienna is calling for help to modulate a Laser on 38kz carrirerfreq.

paul1598419

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It's not lag as such. These DPSS lasers average out rapidly changing power levels of 808 nm light going into then, and the actual solid state laser makes them too slow to transmist 38 kHz signals.

Any LED or direct lasser diode would have no problem with this, probably you can modulate those into the gigahertz range as they do in fibre optics for internet connections ;)
Is this something you know for a fact or are you just assuming they cannot be modulated at 38 Khz? I have modulated them at 5 KHz and know that they can certainly do that. Where is the cutoff if 38 KHz is too high? It is certainly above 5 KHz.
 

wranox

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Thanks thanks thanks a lot for all reply . You support my Projekt were well.
i am sorry that i can't say more details of the Projekt i this stage now. But so far in Futura people work whit is so thats the reason for the max 5 mw and fast and short puls to get the ID info so secure as possible in the tagetsystem befor we have some retina damage of some users .
And yes the ID is a binär code 8 bit opening 3 times 8 bit ID ans 8 bit close . It is nor a Projektor
The Challenge is that the target is moving.

The Summary of all for kindly postings for me is i need a direct laser diode like a 520 nm and a TTL driver board drive from a pin of the Arduino.
If somebody have a idea in which Shop i can buy this parts in good Quality please tell me,
Greetings from the snowy Vienna.
 

Immo1282

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Usual port of call for diodes & copper modules (which house the diodes) round here is DTR's Laser Shop but there may be EU local sellers which might work out cheaper and faster as they won't be shipping from the USA. DTR also doesn't carry any of the drivers you need - but he's a fairly active forum member around here.

I know OdicForce (UK) have a range of drivers, including ones with a TTL control input and also direct-diode green modules - but I'm not sure if their drivers are capable of switching at 38kHz - but there's a start anyway.
 

diachi

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Since the OP isn't using this in a projector the fact that there is some amount of lag in the solid state laser shouldn't matter. I don't know specifically what this project is, but it seems to be for communication as the OP is using it to send a binary code.

The lag results in large rise and fall times, that's why it's an issue. If it was just a delay with the output maintaining the same waveform that'd be less of an issue. You used to see it in projectors before everyone went diode (473 was the worst). If you projected a series of dots or dashes they'd all have "tails" at either end due to the slow rise/fall times. If you modulate fast enough it just turns into ripple on the output.

I can't find an example just now and I don't have a DPSS green with modulation on hand to provide an example with on the scope.
 

paul1598419

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You might consider using a 505nm diode which can be had on eBay from many sellers there. It is a Sharp diode and it less expensive than the 520nm direct diodes I've seen. If you do go this route, keep in mind that these are case positive diodes. As long as you isolate them from the rest of the host you won't have driver problems with them. These can be driven at 5 mW if you so desire and should be the least expensive alternative for your project.
 




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