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Question about diy laser galvo scanner

williamprvz

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I would like to build a laser scanner, but I have a few question before buying part,

I found a galvo kit online and after reading the sticked tutorial I found out i need : a digital to analog converter, a laser and it's driver.

for projecting indoor what laser power is enough ? what driver do i need for it ? is it possible to regulate the laser intensity or it is just on and off ?

the diy dac tutorial has a guide to correct the output of the dac but it's seems that it output +5v/-5v when the galvo kit require +15/-15 volt. Do i need to amplify again ?

thanks for your help.
 



lasersbee

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The best way to start is with information.... a lot of it....
Google is your friend......

To get you started since you have no experience with
Lasers.... a 5mW RED Laser is enough to see indoors and
searching the forum will find you a suitable driver if
you can't find a ~650nm RED Laser.

Jerry
 

williamprvz

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it's hard to find the correct information, i found quite a few already that's why i'm asking here for more precise info. not a lot of peoples documented the process of diy galvo. also one of the link in the stickied thread is down.
 

Junkers

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What driver you'll need is relative to the laser. Expect anywhere from 4V-30V at maybe a couple of amps. Probably best to just get yourself a small bench supply as you're only getting started.

I looked into the idea of building a galvanometer a number of years ago but to be honest for laser light shows there are so many options for such little money. Anything you build will be mediocre by comparison as they are finely tuned systems. I think the entry level 15/30 KPPS systems run for around $100 USD. Have a look at this.

As for DACs, have you ever messed around with microcontrollers before? You can buy ILDA driver cards but from what I recall the information on them seemed relatively obscure, the cards themselves expensive, and the inputs/outputs tended to be older RS232 protocols. Although now looking through ebay I see this which claims to be good value but seems very expensive for what it is (at least in terms of hardware). If you're looking for a project maybe playing around with an Arduino/embed microcontroller and generating your own analog drive signals might be a better project?

Oh, and a +/- 5V output will just produce a smaller image. You can set up an op-amp circuit to amplify the output of your DACs but you would need +/- 18V to get the max +/-15V out for your system. Again, where a decent 3 channel bench supply would come in handy.
 
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williamprvz

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thanks a lot for your detailled answer,

Can you post a link to said tutorial?
this tutorial show how to correct the output of a sound card wich i plan to use to make the dac, i think i misread and the input of the said corrector should be +5/-5

laserpointerforumsXcom/threads/sound-card-dac-tutorialX40569/page-3#post-686384 (replace the X with dot)

Have a look at this.
this type of kit is what i plan to buy, but it's not complete as the dac and laser is missing. I think I will follow your advice since I've already messed around with microcontroller and amp op.

but last question is for the laser, I wouldlike to know if it's possible to buy a higher powered laser and change it's intensity so i can use it both for light show and laser engraving or laser only function at a given power.
 

Junkers

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Yes, you can control the intensity but generally they don't have linear characteristics. It varies from diode to diode however, just be aware that it won't be a case of 0-5V ~ 0-100%. You can control them with PWM but you'll be momentarily be blasting 100% power which may be dangerous if it were to reflect sharply. Invest in some decent goggles.
 

williamprvz

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Yes, you can control the intensity but generally they don't have linear characteristics. It varies from diode to diode however, just be aware that it won't be a case of 0-5V ~ 0-100%. You can control them with PWM but you'll be momentarily be blasting 100% power which may be dangerous if it were to reflect sharply. Invest in some decent goggles.
So i guess for security reason it's better to buy 2 different laser. If I were to power one with a standard power supply, can I make the laser blink with a square wave to draw different point for example ? or do I need a special driver made for it ?
 

Junkers

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Yeah, might be wise to start off with something low power as lasersbee said. The diodes he mentioned can be had for a dollar or less. To switch them using a regular supply you would need to setup a low side driver, basically a transistor or mosfet connected following the laser. You would switch it using whatever micro setup you come up with.
 

icecruncher

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This is just an opinion, but if you are having trouble with finding info, Going to a LEM would be super helpful for you. You would get to see many projectors from the home built to professional, firsthand (Once Covid-19 dies down)
At last years SELEM, Mariomaster had a homebrew laser projector he built with minimal parts and a thrown together cage, but the output was impressive for what it was.

If you want to know all about scanners:

Try Laser Scanners Book by Bill Brennan, president of Pangolin.
Pangolin currently make the best scanners in the world, Saturns
They are stupid expensive at $2495 a set by special order, if you can get one and that's only just for the scanners.
But they have the best specs and it gives you a high point to know what can and can't be done.

On the other end of the spectrum are the ultra cheap Chinese and home-brew. I picked up two sets of 10K Chinese scanners for $20 each at SELEM last year from D Kumpula. Complete with driver boards. He does a lot of builds and sometimes has leftover unused parts that are basically junk but fun to play with.

If you want to know about lasers:

Sams Laser BIble by Sam Goldwasser covers almost anything you want or need to know

Otherwise read these forums for the latest info on diodes and techniques.

Links below
 




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