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Need help building laser module for engraving

Equizer

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Aug 17, 2019
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Hello!

I need help with building not very powerful laser engraving module for a small scale home grade stuff, for example - burning away thin coating of paint from metal for chemical etching, burning pictures on wood, etc.

My plan is to buy a PLTB450B or M140, so i wanted to know is there a significant difference in this diodes for my application, and which one may be better suited for it?

But the core of my questions is about cooling the laser diode, because i want to achieve a continuous operation time of maybe 20-30 minutes (the more the better). As a heatsink/host for the diode i want to use a heatsink from a "500 mw" chinese laser module, which hosted a blu-ray diode (3.6 mm).
This heatsink/host comes in two parts:

1) Black anodized aluminium body with 18mm in diameter hole and a small fan mounted on top (not shown).

DSC_0608---.jpg

2) Aluminium laser host 18mm in diameter with focusing lens and a hole enlarged to accept 5.6mm diode

DSC_0611---.jpg DSC_0613---.jpg

When the diode is installed it screws pretty tight.

DSC_0614---.jpg DSC_0618---.jpg

DSC_0615---.jpg

So my question is: Will this setup be able to successfully transfer heat away from PLTB450B or M140 and provide long continuous operation, given the laser diode's current is set to value recommended by it's datasheet? Also, will this lens be capable to focus the beam efficiently?

Alternative variant is to buy this host on ebay and fit it into original black body, will this setup work? Will it be able to efficiently focus the beam?

If not, what heatsink/host can you recommend?


Thank you all in advance!
 



Philipnzw

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May 19, 2019
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Heres a brass version of the module, it is designed to fit those 5.6mm diodes and should be better than your current solution of drilling out the original. Any laser above 500mW should be used with glass lens if you are doing 20-30 minutes of use.

However if you must proceed with your current set up, i think adding a little amount of thermal paste would help to conduct the heat better. Just make sure not to cover your diode with it. The lens you have now is most probably some kind of acrylic lens so i'll recommend you to switch to a glass one, be it a 3 element lens or G2....yadada, as long as its glass. Those cheap acrylic lens tend to melt under higher powered lasers.

get something like this,
https://item.taobao.com/item.htm?spm=a1z0k.7385997.1997985097.d4918997.4fb963a6BywdVa&id=534436504696&_u=t2dmg8j26111

Cheers and good luck.
 

Anthony P

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I noticed from photo that your diode does not go all the way in to the module. It should have a shoulder machined into it so the back of the diode fits flush. A good module also has a back-half that contacts the edges of the back of the diode. Also, here is good source for CNC Laser diode parts and whole assemblies:
I can not personally answer your question about continuous operation, but I would at least research TEC cooled host/modules.
 

GSS

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Is this a project you wan't to do for fun?
There are complete units with constant cooling on ebay for around $30 to $40 doing 2.5W of 445nm. I'm sure you have seen them?? as you seem to have the basic labby kit.
 
Last edited:

Equizer

New member
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Aug 17, 2019
Messages
6
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Heres a brass version of the module, it is designed to fit those 5.6mm diodes and should be better than your current solution of drilling out the original. Any laser above 500mW should be used with glass lens if you are doing 20-30 minutes of use.

However if you must proceed with your current set up, i think adding a little amount of thermal paste would help to conduct the heat better. Just make sure not to cover your diode with it. The lens you have now is most probably some kind of acrylic lens so i'll recommend you to switch to a glass one, be it a 3 element lens or G2....yadada, as long as its glass. Those cheap acrylic lens tend to melt under higher powered lasers.

get something like this,
https://item.taobao.com/item.htm?spm=a1z0k.7385997.1997985097.d4918997.4fb963a6BywdVa&id=534436504696&_u=t2dmg8j26111
Thank you for links and your suggestions, it is very helpful!
 

paul1598419

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You will be disappointed with any 2+ watt laser you are using to ablate with. It is just not enough power density.
 

Equizer

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Aug 17, 2019
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I noticed from photo that your diode does not go all the way in to the module. It should have a shoulder machined into it so the back of the diode fits flush. A good module also has a back-half that contacts the edges of the back of the diode.
This alumnium host tightly presses onto front and back sides of the diode flange like in the picture below (not to scale), though sides left in the air.
drawing.png

Anyways, thank you for link to the shop!
 

Equizer

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Aug 17, 2019
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You will be disappointed with any 2+ watt laser you are using to ablate with. It is just not enough power density.
I use very thin coatings of paint, so my current "500mw" laser is doing not so bad on it. As i said, it's not my goal to do things which require a lot of power like marking anodized aluminium, for example.
 




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