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Advice on what components to buy for my first laser diode?

Andratos95

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Hello,

I have decided that I would like to build a high power blue laser, however I am quite confused on whether I am selecting all the parts I need.
Since it is my first build, I am not interested in making it as a hand-held pointer, but more as a tabletop laser.

My idea was to use the NUBM08 laser diode, which apparently is a 4.75W laser. To host the laser, since it is a 9mm laser diode, my idea was to use this housing from AliExpress:

Screenshot_20220506_210532_com.alibaba.aliexpresshd.jpg

Finally, I was thinking of building a simple LM317 current regulator to drive the diode (will that suffice or not?).

Is there anything else I am missing? Do you think the parts I have proposed will fit with each other?

Also, I have read that some people buy "G2" or "G8" lenses, but the housing I am looking at doesn't use this nomenclature. Do I need to buy this lens separately, or is the lens included with the housing above also acceptable?

Thank you very much!
 



Shmackitup

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The NUBM08 has a fixed lens attached and won't have an adjustable focus. That looks like an acrylic lens so it would just melt anyways.....
 

Andratos95

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The NUBM08 has a fixed lens attached and won't have an adjustable focus. That looks like an acrylic lens so it would just melt anyways.....
Do you have any suggestions? The ad on AliExpress states that it is a glass lens though...
 

Andratos95

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The NUBM08 has a fixed lens attached and won't have an adjustable focus. That looks like an acrylic lens so it would just melt anyways.....
By the way... I think I have read that the NUBM08, when used as a single diode, should be driven with around 3A (although I'm not really sure if that refers to the single diode or the diode bank). But the LM317 I bought only is rated up to 1.5A. Does this mean that it's impossible to use the typical "LM317 driver" that I always see on YouTube to drive the NUBM08?
 

Shmackitup

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By the way... I think I have read that the NUBM08, when used as a single diode, should be driven with around 3A (although I'm not really sure if that refers to the single diode or the diode bank). But the LM317 I bought only is rated up to 1.5A. Does this mean that it's impossible to use the typical "LM317 driver" that I always see on YouTube to drive the NUBM08?
Whether you run a single diode or the entire bank, you would only run it at 3A. The diodes in the block are in series so you would increase the voltage and not the current. The NUBM08 will run just fine at 1.5A but it will not be anywhere near it's full output capacity. You will not be able to use a focusing lens in that module with the NUBM08 unless you remove the stock "G-Ball" lens from the diode. However, removing this lens exposes the internal components of the diode to the atmosphere and will greatly reduce the lifespan of the diode.
 

Andratos95

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Whether you run a single diode or the entire bank, you would only run it at 3A. The diodes in the block are in series so you would increase the voltage and not the current. The NUBM08 will run just fine at 1.5A but it will not be anywhere near it's full output capacity. You will not be able to use a focusing lens in that module with the NUBM08 unless you remove the stock "G-Ball" lens from the diode. However, removing this lens exposes the internal components of the diode to the atmosphere and will greatly reduce the lifespan of the diode.
Thank you for the exhaustive reply, that helped clarify many things I wasn't sure about. Do you think this buck converter would work as a driver?
Also, one last question...
It is my understanding that what I want to do is set the current, as the driver adjusts its own voltage to accomodate for the fact that the internal resistance of the diode changes (which goes down as the diode heats up cause that's how semiconductors work) to maintain a fixed current. This means that if I were to measure the voltage across the diode over time, it will increase, right?
So... If I were to use a buck converter such as this one, I would perhaps connect it to some battery (say a 9V battery), then I would regulate the current to be 3A on the output... But what do I do with the voltage? On the data sheet it says that the operating voltage of this diode is between 3.6 and 4.8 V... But how can I make sure that this is always the case, since I'm already setting the current to be constant?

Not sure if my question is very clear, sorry
Screenshot_20220507_120524.jpg
 

Anthony P

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The hardware you have selected is fine except as Shmackitup mentioned about focus lens. A 9v battery will not work. They can't supply adequate amperage. I strongly suggest spending the extra money for a real laser diode driver and use 2 lithium batteries in series (18650). I would pull fan power off the batteries before the driver. A regulated wall adapter could be substituted for the batteries. DTR can preset most drivers to your desired amperage.
 

Andratos95

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The hardware you have selected is fine except as Shmackitup mentioned about focus lens. A 9v battery will not work. They can't supply adequate amperage. I strongly suggest spending the extra money for a real laser diode driver and use 2 lithium batteries in series (18650). I would pull fan power off the batteries before the driver. A regulated wall adapter could be substituted for the batteries. DTR can preset most drivers to your desired amperage.
Hey thank you so much for the reply!
I have a some questions about what you said...
1) I don't mind for now to use just a wall power adapter as I just would like to learn about laser diodes basics in my own "lab". However I am really confused about the voltage I need. The LD says that the operating voltage is between 3.6 to 4.8 V (see attached image, last table on the bottom). Does this mean that if I were to use a 12 V wall power supply this will destroy the diode? I know I'm setting the current to 3A, but I don't understand how the voltage comes into play...
2) I am sure that the drivers from the website you provided are excellent, however it appears as ordering from where I live (sweden) would end up costing me an excessive amount of money. Also, I would really love to build my own driver "from scratch". I noticed that there's an alternative to LM317 called LM338 which works in the same way but also supports up to 5A. Could that be used to limit the current to 3A as well? Does it make sense to use a potentiometer in series with the feedback resistor in the linear regulator so that I can actually adjust the current from 0 to 3A and gradually increase the laser intensity?

Thank you!
 

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Anthony P

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A little over voltage does not hurt. It is just gets hotter. 12v may be a bit much. I have never tried a LM338 but is seems plausible. I know the LM317 does a good job for diodes rated for less than 1A. I would not hesitate to try a 338. Just test it with scope and "dummy load". As for a pot adjustment... I usually put a fixed resistor that prevents the possibility over amp then a pot in series.
 




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