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Help focus my first laser!

BenA237

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Hey y'all, I finished my first laser build a few months ago and I was originally happy that my build worked with no problems. This is the link to the cheap diode I purchased: https://www.amazon.com/gp/product/B00HFHMIFG/ref=oh_aui_search_detailpage?ie=UTF8&psc=1. (this was before I knew about this forum, I should've bought from DTR(?))

The only thing is, I would like my beam to circular and hopefully smaller. Im wondering if it is just my laser diodes divergence (why it was so cheap) or maybe the lens is the problem? here is a photo of the beam when I adjust the lens all the way down: Imgur: The most awesome images on the Internet

I just want a laser that is relatively bright, but I don't necessarily need it to burn (although that would be a nice addition). Sorry if I messed anything up, this is my first post ;)
 

diachi

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Hey y'all, I finished my first laser build a few months ago and I was originally happy that my build worked with no problems. This is the link to the cheap diode I purchased: https://www.amazon.com/gp/product/B00HFHMIFG/ref=oh_aui_search_detailpage?ie=UTF8&psc=1. (this was before I knew about this forum, I should've bought from DTR(?))

The only thing is, I would like my beam to circular and hopefully smaller. Im wondering if it is just my laser diodes divergence (why it was so cheap) or maybe the lens is the problem? here is a photo of the beam when I adjust the lens all the way down: Imgur: The most awesome images on the Internet

I just want a laser that is relatively bright, but I don't necessarily need it to burn (although that would be a nice addition). Sorry if I messed anything up, this is my first post ;)

FYI, that module is from DTR... he has an amazon store too.

You can't really make the beam from these circular without lots of corrective optics or fiber coupling. It's just a result of the way these diodes are constructed, not much can be done unless you want to add more optics (and lose some power as a result). All diodes at these sort of powers have the same issue, the output is a stripe rather than a round dot.

Hard to see how large the spot is in that photo, can you take a picture through your safety glasses with a ruler next to the dot? Let us know the distance from the laser to the dot too.

Best focus is not necessarily achieved when the lens is screwed all of the way in, sometimes you can have the lens 1/4 of the way out of the barrel before you get a real good focus, depends on the lens and diode.
 
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BenA237

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Ok so I used my safety goggles and got some measurements (I could not take a photo of it because my phone's camera is low-key broken), but here is everything I gathered

~1.8 inches for length
~.7-.8 inches for the width
making like an ice hockey rink shape lol
laser was 28 inches off the floor, and focused to the best I could, which was pretty much up as close I could, because the more I pulled the lens out the "rink" would just keep getting longer
 

diachi

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Ok so I used my safety goggles and got some measurements (I could not take a photo of it because my phone's camera is low-key broken), but here is everything I gathered

~1.8 inches for length
~.7-.8 inches for the width
making like an ice hockey rink shape lol
laser was 28 inches off the floor, and focused to the best I could, which was pretty much up as close I could, because the more I pulled the lens out the "rink" would just keep getting longer

Some lenses need to go in further too, which means taking the knurled adjustment ring off (it just screws off), allowing them to go in further. The correct focus isn't usually found when the focusing ring is pressed against the module.

That said, this module comes with an acrylic lens which is unable to handle the output power of this diode for long. You should replace the lens with a a glass lens. DTR has several options.

https://sites.google.com/site/dtrlpf/home/glass-lenses

The 405-G-2 will give you more power and a smaller beam close up, but somewhat worse divergence. The 3 axis will give you less power and a somewhat wider beam close up (not massively larger, a few mm give or take) but will improve divergence over the G-2.

You may need to remove the focus ring with either of those options too, I'm not sure.
 
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paul1598419

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This diode is not the worst for giving that rectangular beam profile when properly focused. If you get the G-2 or three element lens from DTR, you shouldn't need to remove the focus knob as all his lens assemblies will bottom out before you run out of room. That acrylic lens needs to be replaced immediately as it will melt very quickly with this diode. I'm surprised it hasn't already. The three element lens doesn't actually bottom out, but focuses long before you run out of room.
 
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BenA237

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omg you are a GOD!!!!!!!! I can't believe it, but I did need to remove the focus ring! now in focus at the same distance, the spread is suuuuuper small. I'm so happy, how can I thank you lmao.

One last thing, for normal laser purposes (i mean lasers in visible light spectrum, especially blue lasers) does larger wattage mean a brighter beam? I really like it, but I'm thinking about expanding my collection. Like if I wanted a beam like this: https://www.youtube.com/watch?v=puZFaIDHG2I&t=1s (which is a really cool sky blue, NUBM07E)
Should I try to get this diode because it looks really cool or do you have another that you recommend. Lol Im sure they are all good, but I want "the best" for under $150
 

diachi

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omg you are a GOD!!!!!!!! I can't believe it, but I did need to remove the focus ring! now in focus at the same distance, the spread is suuuuuper small. I'm so happy, how can I thank you lmao.

One last thing, for normal laser purposes (i mean lasers in visible light spectrum, especially blue lasers) does larger wattage mean a brighter beam? I really like it, but I'm thinking about expanding my collection. Like if I wanted a beam like this: https://www.youtube.com/watch?v=puZFaIDHG2I&t=1s (which is a really cool sky blue, NUBM07E)
Should I try to get this diode because it looks really cool or do you have another that you recommend. Lol Im sure they are all good, but I want "the best" for under $150
Glad that worked out, although you definitely still do need to replace that lens.

Yes, more power results in a brighter beam for any given wavelength. Although the relationship isn't linear, so double the power doesn't mean double the brightness.

As for the LD, yes, that's probably the best choice if you want lots of power at that wavelength. Those LDs are 465-470nm usually and are as a result a much lighter shade of blue compared to the diode you have. They're also somewhat brighter, watt for watt, than what you have. Our eye's get more sensitive as you move up towards 555nm from blue and then drop off again towards red.

 

BenA237

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Ok, so thats why we can barely see violet... that makes sense. So G-2 will give more burning power but will have a slightly larger divergence (is it that big of a deal) and the other good one makes it wider, does that make it brighter you think? But yeah that LD looked right up my ally, light blue man :drool:
 

paul1598419

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I use G-2 lenses or another single element aspherical lens for most of my builds. It is only really noticeable on diodes that have very poor divergence specs. Those are, but not limited to, the NUBM44, the ML501P73 and the Oclaro diode of the same wavelength, and several diodes over 3 watts in power.
 

BenA237

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I use G-2 lenses or another single element aspherical lens for most of my builds. It is only really noticeable on diodes that have very poor divergence specs. Those are, but not limited to, the NUBM44, the ML501P73 and the Oclaro diode of the same wavelength, and several diodes over 3 watts in power.
Thanks Paul! Sounds like I need to get some G-2's for all my laser builds now! I don't think the NUBM07E has a poor divergence so I should be good.

Another question, can I purchase any old host assembly because most(?) LD modules have the same shape. I have a cheap survival laser host, C6 i think..., but for my next build I want something that looks classy loll
 

paul1598419

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It really depends on the amount of current you are setting the driver to push. Anything over 2 Amps and the driver should be heat sinked. If you are pushing over 2.4 amps I would consider a larger heat sink for the module, though most are ~12 mm in diameter and can fit in most hosts, if you want more than a short duty cycle, go for a larger heat sink. Anything pushing 4+ amps should be in a copper heat sink IMO.
 




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