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Author Topic: Focusing an IR laser diode  (Read 28047 times)

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Offline frasej

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Focusing an IR laser diode
« on: December 05, 2013, 04:29:06 PM »
I have a 4W IR laser diode and driver.  It has a big focus ring on the front that moves the lens up and down (or in and out).  It seems that at whatever position I put it, and whatever distance from my target, it's just a fairly large dot, not a pin hole like I'd expect.  My observations are via a wireless camera and I am viewing it on my PC.  It will melt black plastic, but again, not in a small dot like I expected. Any ideas on how to focus this thing.  Oh, you can see the laser module I purchased here: http://www.ebay.com/itm/Focusable-4W-808nm-810nm-Infrared-IR-Laser-Diode-Module-5V-Power-Supply-TTL-/120921387123?pt=LH_DefaultDomain_0&hash=item1c2779f073
Jay

Offline Tweakie.CNC

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Re: Focusing an IR laser diode
« Reply #1 on: December 08, 2013, 05:21:19 AM »
Perhaps the easiest solution is to create a GCode program that just fires a single, fast, dot.

Use a piece of wood as the work, fire the ‘dot’ - when complete observe the size on the dot on the surface of the wood. Adjust the focus and fire another dot and repeat until you can obtain the smallest sized dot on the surface of the wood.

Now switch the wood for a piece of black anodized aluminium and repeat the process, slightly adjusting the focus (as necessary) until you can produce the smallest possible size of dot.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline frasej

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Re: Focusing an IR laser diode
« Reply #2 on: December 08, 2013, 05:04:38 PM »
I already tried that and got nothing.  No burning, nothing.  I think the unit may be defective.  When I removed the lens, I could see the diode was off center, almost against the edge of the housing.  I believe that is why I can't focus it properly.
Jay

Offline Tweakie.CNC

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Re: Focusing an IR laser diode
« Reply #3 on: December 09, 2013, 01:47:54 AM »
Quote
When I removed the lens, I could see the diode was off center, almost against the edge of the housing.  I believe that is why I can't focus it properly.

Looks like a new unit is required then.  :(

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.

Offline frasej

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Re: Focusing an IR laser diode
« Reply #4 on: December 10, 2013, 12:39:17 PM »
oh well, back to using my 1.5W 450nm Blue diode module.  Actually, it does surprisingly well.
Jay

Offline frasej

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Re: Focusing an IR laser diode
« Reply #5 on: December 13, 2013, 10:50:33 AM »
Tweakie, I finally got the IR laser to focus.  The reason I couldn't focus it before was I was too close to the object to be engraved.  It turns out that the lens has an unbelievable long focal length.  While I was thinking it was 2 to 4 inches, it turns out that 20 inches would have been a lot closer.  So I have had to mount the laser well above the router table.  Sheesh, who'd a thunk?
Jay

Offline Tweakie.CNC

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Re: Focusing an IR laser diode
« Reply #6 on: December 13, 2013, 11:27:15 AM »
Hi Jay,

I am pleased you got it sorted.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Focusing an IR laser diode
« Reply #7 on: February 19, 2015, 09:12:59 AM »
I have a 4W IR laser diode and driver.  It has a big focus ring on the front that moves the lens up and down (or in and out).  It seems that at whatever position I put it, and whatever distance from my target, it's just a fairly large dot, not a pin hole like I'd expect.  My observations are via a wireless camera and I am viewing it on my PC.  It will melt black plastic, but again, not in a small dot like I expected. Any ideas on how to focus this thing.  Oh, you can see the laser module I purchased here: http://www.ebay.com/itm/Focusable-4W-808nm-810nm-Infrared-IR-Laser-Diode-Module-5V-Power-Supply-TTL-/120921387123?pt=LH_DefaultDomain_0&hash=item1c2779f073

I am looking into getting the same laser. Do you mind answering some questions for me, before i buy it? I am looking to cut some 2mm thick PVC. I already did some tests on a CO2 laser, with great results. But this would be a better fit for mounting on a CNC machine.

-will it cut that?
-How slow does the CNC have to go to cut?
-have you had any problems with the laser/power supply?
-what is the duty cycle of the laser, how long can it be on for?
-is it an instant on, or does it have to "warm up"?


THANK YOU!!!!! :)


Offline frasej

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Re: Focusing an IR laser diode
« Reply #8 on: February 19, 2015, 10:14:03 AM »
I never did get that particular laser to work properly. Eventually, I think, I over powered it and burnt out the laser.  >:( I did, however, end up using a 2.5 watt 450nm laser that worked quite well.  As I recall, PVC should never be cut with a laser for a couple of reasons; 1. The fumes are toxic. 2. The fumes can damage the lens of the laser.
You could use it to cut very thin acrylic, as long as it isn't clear acrylic.  For the clear stuff, you'd need a much higher powered laser, such as a CO2 40-50 watt laser. When using lasers to cut anything, always have plenty of ventilation, you never know what's going to give off toxic fumes.  :)
Jay
Re: Focusing an IR laser diode
« Reply #9 on: February 24, 2015, 09:30:35 AM »
Thanks frasej! We are aware of the dangers of cutting PVC with a laser. We have safety measures already in place.

since your laser is dead, would you be willing to sell it to me? I would need everything that came with it, the power supply, the TTL, and the housing.


Thanks!