Weird pattern on new 520nm green

[Scottydog]

Hello everyone!

First post but a long time reader. I have two sanwu lasers, a 200mw red and 100mw green. Both lasers are very good, i bought off the advice members given to others on here. Thanks for that! ☺.

I recently thought I'd step up a league or two... I went and bought a 800mw 520nm laser from bit lasers. Excellent service and answered my questions almost immediately. However I think there may be something wrong with the lens or diode.

I'd like you guys to have a look at this picture and tell me if this is normal before I waste more of his time asking newb questions.

Thanks!

 

[Radim]

Seems to me to be a dirty lens. Can you take more pics of that?
Edit: But maybe is something wrong with it - that rectangle shape...

 

[BobMc]

Hello everyone!

First post but a long time reader. I have two sanwu lasers, a 200mw red and 100mw green. Both lasers are very good, i bought off the advice members given to others on here. Thanks for that! ☺.

I recently thought I'd step up a league or two... I went and bought a 800mw 520nm laser from bit lasers. Excellent service and answered my questions almost immediately. However I think there may be something wrong with the lens or diode.

I'd like you guys to have a look at this picture and tell me if this is normal before I waste more of his time asking newb questions.

Thanks!

Real curious on the answer. I got a 520nm 120mw from DTR that does the exact same thing. When I spin the lens the 'square' does not rotate so I'm guessing the problem is in the diode. I just thought it was a inner reflection, that was just normal. Will be interesting to see what comes of the question. Thanks for asking.

 

[Eracoy]

That rectangle shape is perfectly normal with this diode when using a G2 lens. A 3-element won't have this nearly as strong. It come from reflections of the shape of the end of the emitter inside the diode, I think, and a G2 is closer to the diode and catching more of that light.

 

[Scottydog]

This is what it looks like with the lens out of focus. The rectangle gradually gets smaller untill what you see in the first post.

 

[Scottydog]

That rectangle shape is perfectly normal with this diode when using a G2 lens. A 3-element won't have this nearly as strong. It come from reflections of the shape of the end of the emitter inside the diode, I think, and a G2 is closer to the diode and catching more of that light.

Ahh, thank you. Am I right in thinking a g7 lens is 3 element ?

How much power would I roughly loose by getting rid of that rectangle ?

Do you also know if bitlasers 4.5w blue has this same "quirk" ?

 

[CynicalBrad]

Perfectly normal. G2's do it G7's do it, even 3E's do it just not as badly. It is stray scattered emissions in the die getting focused in the output. It is just more noticeable in higher powered/more visible builds.

 

[GSS]

Ahh, thank you. Am I right in thinking a g7 lens is 3 element ?

How much power would I roughly loose by getting rid of that rectangle ?

Do you also know if bitlasers 4.5w blue has this same "quirk" ?

Could be up to 30% loss with the 3 element lens which isn't the same as a G7.
G7 is worth a try to and should help some to correct the spot with a bit of power loss but no where as much as the 3 element.
Alot of members seem to enjoy this G7 with it balance of power and spot correction.

 

[dden4012]

Kind of looks like the spring is giving some reflections as well from that lower left arc. The 2 element lens is a good option and it would be hard to notice the output loss visually. It is weird how some of my single mode diodes give the box reflection and others do not with the G2. The Sanwu G7 is a great lens but I do not care for its setup in the lens barrel, only get 1 or 2 threads into the module at focus and lots of wobble from that. Dpss is where its at with green and beam.

 

[Benm]

It is really hard to tell from that picture. Perhaps you could post one that is far under-exposed to the actual beam profile is visible?

As for things like springs getting in your way, or having a lens only a few turns inside the module: Try putting some teflon tape around it. This is not sticky tape, but just a very thin ribbon of teflon often used when installing gas (methane, propane/butane) fittings wrapped thinly around the threads.

It can help reducing any wobble and provide a bit of resistance to rotating the lens, and can be removed without leaving a trace if you wanted to. It's not expensive either, a small roll costs a few dollars but lasts dozens of lens fittings, you generally need only a few cm.

 

[GSS]

Kind of looks like the spring is giving some reflections as well from that lower left arc. The 2 element lens is a good option and it would be hard to notice the output loss visually. It is weird how some of my single mode diodes give the box reflection and others do not with the G2. The Sanwu G7 is a great lens but I do not care for its setup in the lens barrel, only get 1 or 2 threads into the module at focus and lots of wobble from that. Dpss is where its at with green and beam.

dden, where is your source of the 2 elements?
I have one in shorter barrel and can't remember as to where I got it. I will say iv'e tried it breefly on a PLP520B doing 170mw with its now 3 element and was nicely surprised by its crispness but did see some wings. I haven't yet put to much time into play with this 2 element as i'm not sure from what source it came from and its true capabilty's.

 

[BowtieGuy]

GSS, DTR has a 2 element lens for the 520nm diodes, -Here-.
I'm pretty sure it's in the standard length barrel, ~10mm long.

 

[GSS]

Thanks Bow, I usually check Dtr's sight easily at least 2 times a day..just for idea's and new prices:can:
Mine is in a shorter barrel and i'm guessing who ever I got it from just bought the lenses and put them in this barrel. dden seems to swear by them and my first opinion off them wasn't to bad

 

[dden4012]

They are shorter than the 3 element lens. DTR is the place. They are coated 400-600.

 

[Scottydog]

sorry for the late reply guys, been busy.

ill post beam shots later if needed, but i think you have all cracked it to be honest.

so, these DTR lenses are the way to go for 520nm then ? whats the power loss like compared to a G2 lens ?

also, does anyone know if the bitlasers 4.5w blue have the same problem ?

thanks for all the replies!

 

[GSS]

Not much info as to what Bitlasers uses for that 4.5W unless i'm missing it but it sure looks like a 07E. His spec's say a single element lens but that diode is I believe a set Gball lens with no focusing and its set to infinity focus. I don't know if he took the Gball off and that "single element" is a G2 now? You can look at DTR's site who sells these 07E's and see what he see's from them. Plenty of members have built quite a few also.
If a 3 element would rob around 30%
I would think a G7 would be 10% to 15%
and those 2 element would be close, but at $9 to $15 each why not try them?

Edit: The 4.5W Bitlaser is a focusable unit so i'm not so sure as to what he's using?
ScottyDog, have you seen any of the reviews? Just use the search option below and you will find one kinda recent.