Help improving beam collimation/side artifacts

[overambitious]

Hi all,

I've been working on a 2W 462nm build for a while now, and tonight I was able to fire it properly (outside at full power with a glass 3-element lens) for the first time. However, I'm noticing that there's still some scatter occurring out to the sides along the same plane where the out-of-focus beam spreads. (see image)

How can I get rid of these artefacts? Is this something I can fix with focusing? Do I need to replace the lens? Is it simply inherent to the diode? My goal is the cleanest, tightest long-range beam, not engraving or burning. (unless I can burn at a distance)

Lens: https://www.ebay.com/itm/3-Element-...-445nm-450nm-Laser-Diode-M9-P0-5/323141958403
Diode: https://www.ebay.com/itm/2W-M462-462nm-Blue-Laser-Diode-in-Copper-Module-W-Leads/181462440785
Image (backup): https://i.imgur.com/vub4Uop.jpg

 

[paul1598419]

The only way to remove this is by masking the beam. If you put a 1 inch long cylinder around the laser's output just a little larger than the beam as it exits you will eliminate all the splash you are complaining about. It really is the ONLY way. Most of us are used to it. You won't even see that much as the camera picks it up much better than our eyes do.

 

[paul1598419]

This is mostly the camera. I have seen it before in photos I've taken and only could see it in the photo. There is always some amount of splash when using a laser. Some of it is just reflection off particles in the air, but is so dim only the camera picks it up. You can certainly try using other lenses, but take a photo of it when you do and see if it isn't still there.

 

[trinh hong phuoc]

I think these are objects made up of three elements, he is not familiar with that

 

[Shmackitup]

I've noticed that all the newer 3 element lenses I've been getting have much more artifacts than the ones I was getting about a year ago.

 

[RedCowboy]

Yes and I swear the FL is sometimes different, try the half thread 3E lens, their AR coating is better and the beam looks good.

 

[ZRaffleticket]

That's indeed very normal for 3 element lenses.

 

[RedCowboy]

Some diodes have more than others, a beam expander will help as can a lens flair hider.

 

[aaronnoraa]

To get rid of that splash on the M462 use a G7 lens... you'll also see a considerable gain in output using a G7 over a 3 element. Get it with the 7mm holder if you don't use a focus ring (as in a labby style application or pointer you don't plan to frequently change focus) or get it with the 9mm holder if you do use a focus ring (as in a pointer with a focus cone attached to the threads to easily change focus).

The 7mm holder will have a practically perfect output when the lens is clean on the M462 but it only has about 4 threads remaining when focused to infinity which may not be enough to screw on a focus ring. As others mentioned, the 3 element lens is responsible for the splash wings you're getting, I had the same issue when I had a 3 element on my M462.

Link for the G7 - https://www.sanwulasers.com/product/lenses

Here's a picture of my M462 with a G7. Clean razor sharp beam and no splash. Tasty.

 

[paul1598419]

I'm not so certain the diode in the OP's laser is not an NDB7675. I have both diodes and many aspheric lenses of various focal lengths including the G7 plus a 12 mm FL lens and many between 2.39 mm and 3.4 mm. I have been planning on a new build with one of these diodes. The M462 is my latest acquisition. I still believe that some of this splash is caught by the camera as reflected light off of particulate matter in the air.