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m140 2W laser focusing trouble

akohut

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Hello,

I am building my first laser, a 2W 445 nm diode. I have a cheap 3-lens assembly and am having trouble focusing the laser. I want to burn something! I am finding that the smallest dot happens closest to the lens. Any suggestions on focusing the laser further from the lens?

Thanks
 



RedCowboy

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Are you wearing laser safety glasses?
The safety glasses let you see the focal point so you can adjust it better.
 

akohut

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I will settle for burning anything at any distance for now
 

RedCowboy

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I will settle for burning anything at any distance for now
Multimode diodes diverge rapidly but with a 3 element you should be able to light wooden matchsticks on the bottom end and easily on the head end at 5 feet.
You need to hold steady and put the tightest focus you can get on the edge of the wood and hold it there until you see it glow through your safety glasses, then a flame kernel will pop out and your match is lit the hard way, once you have the kernel then burn under it as smoke is fuel for your flame and you pre heat the next burn area.

What diode are you using, what driver are you using, what battery are you using, do you have it in a good heat sink?

Here is a M-140 using a 1.8amp driver.


REMEMBER to ALWAYS wear your safety glasses because the tiny light sensing parts on your retina do not bleach out to protect themselves against blue light like they do if hit with say a super bright flashlight, so safety glasses are extra important with blue lasers, they are important with any laser over 5mw, but blue has a lot more energy than it appears to. Green lasers look 10 times as bright as blue watt per watt so never try to burn without your safety glasses, you can record your burning and watch it on your pc like this and not ruin your eyes.
Sorry for preaching safety, but it is the most important part of anything you do involving lasers.
 
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Lifetime17

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Hi,

Lens you could use is a G2.
No you need a test load so you don't loose the diode when setting the driver.
If your using a xdrive set to 1.8A you need 2-3.7V cells in series
If you using a Xboost driver set to 1.8A you need only 1-3.7V cell (never 2-cells with this driver)
This info is for the M140/445nm diode.

Rich:)
 

akohut

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Will a multimeter measuring the current work as a test load?
 

Pi R Squared

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Will a multimeter measuring the current work as a test load?
NO! That will only work with a linear driver, if you do that with any other driver it will likely kill the driver. You also haven't answered the question what driver are you using. You can't have trouble burning stuff with an M140, it just isn't possible. Be sure never to drive it above 1.8A max, mine is driven at 1.5A and burns just fine.

Alan
 

akohut

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I also have a m140 and 1.8A driver with a 3.7V 4800mAh battery. Im getting somewhere! Is it safe to turn driver trim pot all the way up without using a test load?

https://youtu.be/r7F8KDw1Iow


Sorry, I dont know how to embed the video. After focusing I am burning.



I dont know which type of driver mine is, here is a link to where I bought it. I cant find anything about xdrive or xboost on it.

445nm 450nm Blue Laser Diode Driver 1 8A Output for 1 6 2W Blue Laser Diode | eBay
 
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Pi R Squared

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I dont know which type of driver mine is, here is a link to where I bought it. I cant find anything about xdrive or xboost on it.

445nm 450nm Blue Laser Diode Driver 1 8A Output for 1 6 2W Blue Laser Diode | eBay
You shouldn't buy cheap Chinese made drivers. It is clearly a boost driver that puts out a max of less than 1.8A. If you don't have a test load, you can adjust the pot and turn it up all the way with the laser powered off. Also be sure your battery is charged.

Alan
 

RedCowboy

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I have used those drivers, they will put out about 1.5 -1.6 amps so you can turn it all the way up if your diode is a m-140, but as it's a boost driver you need a good battery. From your video it looks like you don't have it turned all the way up, or your battery is sagging under load.

Also did you buy your diode new, that is from a trusted source?
Many flebay sellers will sell well used diodes and the weaker version of the M or even sell old used A series as M's


NDB7875 is a better burner, you can get one here:
https://sites.google.com/site/dtrlpf/home/diodes/9mm-445nm
All his diodes are as advertised and you will get what you order.
 
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akohut

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Thanks for all the help guys! I also have an adjustable power source that I can use in place of a battery.
 




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