What type of artifact is this?

[carulli2]

It's a diffraction artefact caused by teensyweensy schumtz on the diode window and perhaps the lens. Maybe a very very tiny scratch.
https://www.researchgate.net/post/W...erference_patterns_generated_by_a_laser_diode

This is just what it looks like.

 

[Cyparagon]

It looks to me like spherical aberration and/or standard interference pattern inherent of coherent light.

 

[RedCowboy]

The best thing to do is try another lens and see what you get, that way you can rule in/out the diode/diode window.

---edit---

Besides that the artifact doesn't look like a big deal anyway, I mean who looks at a half watt 405nm spot that close anyway ???
Do you even notice it during normal operation ?

---edit---

Is that spot focused tight or unfocused?

How about giving your lens barrel a little push in the modules threads and see how much thread slack you have, it might just be pressed to one side or the other and with your lens barrel shortened the amount of misalignment in the thread slack may be more than normal, this may be simple lens misalignment due to thread slack and a shortened barrel.

Try using a stiff spring.

 

[carulli2]

The best thing to do is try another lens and see what you get, that way you can rule in/out the diode/diode window.

---edit---

Besides that the artifact doesn't look like a big deal anyway, I mean who looks at a half watt 405nm spot that close anyway ???
Do you even notice it during normal operation ?

---edit---

Is that spot focused tight or unfocused?

How about giving your lens barrel a little push in the modules threads and see how much thread slack you have, it might just be pressed to one side or the other and with your lens barrel shortened the amount of misalignment in the thread slack may be more than normal, this may be simple lens misalignment due to thread slack and a shortened barrel.

Try using a stiff spring.

The spot was focused. I think it is a slight misalignment of the lens due to the unique design of the sanwu pocket series. I will try and stiffen everything up with some Teflon tape.

Edit: you were right. It was just misaligned due to loose threads.