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What laser power range should I be looking at for this application?

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uCLinux

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I intend to make a laser scanner setup using the 20Kpps galvos that can be found off ebay.

I would like to use this setup to draw text and some patterns (circles, squares) on a wall about 25-50ft away (15 degree setup would be more than enough... even 8deg would probably be more than enough) in an environment that is artificially lit.

Questions:
1.
I only want a one-color system, preferrably green. Given this setup, what power range should be looking for?

2.
I intend to use a TTL laser module. To do blanking for a text/pattern setup like what I describe, what minimum frequency should I be looking at?

Thanks!
 
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Cyparagon

Cyparagon

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Indoor graphics at 50ft? I think 300-500mW should be plenty. Modulation speed should be 10kHz minimum as a rule of thumb. Pretty much all modulation-enabled lasers will do 10kHz anyway though.
 
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uCLinux

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Yes, indoor simple graphics with slightly less than optimal lighting.

Thanks for your thoughts. That's actually a bit higher than I thought it would be mW wise, but slower Khz wise :D

What do you think the minimum would be that I could get away with?
Is there a favorite source for lasers around here too? Sorry if this sounds like a non-researched question [it is].. but knowing just a few helps when I poke around.
 
T

Things

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Be aware that with 20Kpps scanners, you won't be able to do much text before it starts flickering horribly.
 
Cyparagon

Cyparagon

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I don't know if there is an absolute minimum, but it gets pretty dim. I wouldn't go any lower than 100mW myself.
 
ARG

ARG

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uCLinux said:
Is there a favorite source for lasers around here too? Sorry if this sounds like a non-researched question [it is].. but knowing just a few helps when I poke around.
Click to expand...

Lots of people have been buying from meierlight recently. I got a 300mW 532nm lab from meierlight for 220$ shipped. (Email them and offer 220$)
 
vk2fro

vk2fro

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Yeah like ARGLaser said, mieirlight.china on ebay sell dhom lasers which are pretty reliable lasers. The power brick on them is a little large, but certainly not laser projector unfriendly.
 
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uCLinux

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Thanks all, I ended up purchasing one from meierlight. I've also found some great suggestions for safety goggles here which I have picked up.

My next question is where is a good place to find a +/-12 or +/-15v power supply. I can't believe they are this hard to find! And the fact ebay considers a "-" as a symbol to remove a keyword doesn't help matters, haha.
I was expecting it to be much easier to find a caged switching PS.. as easy as finding a normal +12/5/3.3V PS. Guess not! :undecided:
 
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Cyparagon

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This is for the scanners, yes? Are you sure they don't come with a power supply?

You can make one with two regular power supplies:

attachment.php
 

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  • +-12V.png
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U

uCLinux

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This is for the showcard. It expects +/-15v and I was hoping to do this without the 2 ps supply setup to save space :) Honestly I assumed these would be more commonplace than they seem to be now.

Sorry, I should have mentioned this in my last post.
 
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vk2fro

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I have one you can have for $20 plus shipping + paypal fees. Its 15V split rail (the kind you want), at 1A. The split rail supplies are as rare as rocking horse poo, the suppliers know this, and thus the only ones you can find are bloody expensive. I'll probably kick myself for selling this one. It drove a showcard in a cheap laser scanner from china whos lasers died. I have absolutly no desire to see "HAPPY" or the trumpeting elephant or the dancing lady cheap china graphics again. The showcard went in the bin :p

In case you dont want this one, they are called Syncronous or dual rail power supplies

where abouts are you?
 
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uCLinux

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I'm in the U.S. I suspect shipping charges will be high, but in the event I come up with nothing I'll give you a shout. Thank you :)
 
vk2fro

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Wont cost a lot to ship - mabye $10. Its light as a feather (its what you mentioned, one of those switchmode caged PS's).

But yes you could save a bit if you can find one locally. If not feel free to give me a shout. I'll put it aside for you.

Just out of curiosity, how do you plan to control this laser - with the show card alone, or with a computer over ILDA signal?
 
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uCLinux

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I'm not exactly sure how I will put it together yet. I bought the show card primarily for testing reasons, and also with the intention to see their circuit.
I will either:
1. Connect GPIO lines from an embedded linux device to the showcard (hack it).
2. get a cheap usb audio card and hack it to connect to the showcard.

Basically I'm just using the card as a cheap means to do the level translations/etc. If that works out well, I'll probably make an open source usb-ilda unit... assuming one doesnt' already exist haha.

I was going to write my own software to control everything (I intended to just do really simple stuff at first), but I've come across OpenLase which looks really nice. They use the JACK audio rtc setup to spit everything out. It should be perfect for my needs.. I'm not sure how well it will work for high bandwidth laser displays.. something I'll learn about later I suppose.
 
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uCLinux

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Welp, everything came in today and I noticed the 20k galvo driver boards I got have a +/-15v source built into them. How convenient :) ... Right after I bought a nice PS off ebay too (those search terms helped!)
My laser hasn't come in yet, but by a laser pointer I was able to test everything pretty easily.

The galvo driver boards get really hot which concerns me a little. I've worked with stepper motors before and expected heat, but 144F after the system has been shut down for a minute seems high, especially when the manual suggest a max of 115F!
My galvo driver boards juts came with a piece of painted aluminum bolted to it for a heatsink... I'm thinking a real heatsink might help.
I'll probably read a bit more about the heat issue, then machine some new heatsinks with fan bolt holes.
 
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Cyparagon

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Yes, they need to be bolted to a heat sink. The optical base plate is a common solution.
 
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