There is Something "Wrong" With My Beam/Spot

[daguin]

I have had several inquiries about this. I thought that I would place this info in a bit more focused way. This thread focuses on the Wicked Lasers Spyder III Arctic because people with Arctics are who ask most often. However, the info about the diode and beam/spot, in the first part of this post, pertains to ALL lasers made with this 445nm diode.


Before you do anything, make sure that your laser actually has a problem. The diode used in these is multi-mode. It does NOT produce a "spot." It produces several "lines." The higher the mW, the more "lines" produced. The colimator makes the line a bit more of a rectangle, but it is not and will never be (without significant external optics) a round dot. This is what the raw diode output looks like:

Here is link to a great video of what the raw output of the diode looks like at different currents.
Thank you, anselm
http://laserpointerforums.com/f48/video-raw-output-blue-nichia-diode-60488.html

This is what a well colimated "spot" looks like at about 40 feet.

With a higher output lens it is even more elongated. Here is one with a high output lens at the same distance

This is one of the many lies that laser sellers tell about these diodes. They are NOT TEM00! If your "spot" is anywhere close to these, it is as good as it gets. Don't mess with it! You will be taking the chance on breaking your laser for nothing

Also, the higher output lenses may also show a "phantom square" (or other "noise") above the "spot." This is normal. There is always some spurious emission around the edge of the die. Your lens is just picking that up and focusing it along with the main beam. With this diode, sometimes you must adjust your expectations from this diode (or get a lower output lens ) instead of trying to adjust the output.

Finally, the width of the emission often reflects off of the sides of the lens nut. The result of this is a "spray" of light from two opposing sides of the beam

If yours is significantly more elongated than the pictures above, then WL did not adjust it (or maybe assmble it) correctly. Now you have to decide if it is worth taking the chance on breaking it.

The next part deals specifically with the Arctic

There are several "variations" in the Arctic. They are "basically' the same in this area, but there is some variability. This is the basic design.

When you remove the outer "lens" you should see something like this

This is the diode/collimator/aperture assembly

If you removed the whole assembly, it would look something like this

You DO NOT want to remove the entire assembly. This is just to get you to recognize which parts you are going to be working with.


Here is the assembly completely removed

You should be able to see the aperture and the diode holder in this picture. The aperture should unscrew from the diode holder.

Here is the aperture removed

Here you can see the colimating lens which is under the aperture and inside the diode holder.

You have to hold the diode holder in place while unscrewing the aperture. If the diode holder spins, you take a chance of breaking the wires that are attached to the diode or breaking off the diode pins.

If you are successful at removing the aperture, then you have access to the collimator. You can then use a screwdriver (or other tool) to adjust the collimating lens.

In some of the Arctics, the collimator is glued in place. In some of them the aperture is glued in place. If yours is glued in place, you are pretty much screwed. If you can move it, then you can adjust it and then reassemble it. If not, then adjust your expectations and/or attempt an RMA (good luck )


Peace,
dave

 

[Kevlar]

Good sticky Dave.

It will be nice to just link this thread to this most common question.

 

[LORDJET]

Daguin, thanks so much for posting this. good info there! I will add that when I changed out the original lens for a 405-G1, the stock lens did have what appeared to be jb weld. I was able to remove it with an hobby knife. You of course have to be VERY careful in doing this, one slip and you've ruined your original lens!:yabbmad: In fact I think ZAPU discussed this in another thread before.

 

[Garoq]

Great post Dave.

If you don't mind I'd like to add a photo of another "anomaly". A customer contacted me about his beam spot having an odd "hourglass" shape, and sent photos:

After thinking about it for a few minutes while watching the morning news, I attempted to duplicate the effect with one of my units.

He had his lens in backwards.

 

[daguin]

Great post Dave.

If you don't mind I'd like to add a photo of another "anomaly". A customer contacted me about his beam spot having an odd "hourglass" shape, and sent photos:



After thinking about it for a few minutes while watching the morning news, I attempted to duplicate the effect with one of my units.

He had his lens in backwards.

Yep. Thank you. I've seen this one myself :yabbem:

It took me a few minutes to figure out what I had done

Peace,
dave

 

[leftkidney]

I was going to start a new thread about this but decided to post here first


is there a way to make the termination point of the laser smaller at long distances?

I can shine it across a lake that is about 1 mile across at the point where I am doing it - there is a huge DNR sign on the other side that is for the state park - if I shine my 445nm laser onto it and have someone on the other side to measure it it will be like a huge 2-3ft blob

how can I make it focused to a small point - not really worried about power loss through lenses - I have tried a telescope and it made the blob a circle but still huge - also not really worried about portability either

 

[CDBEAM777]

LK,

Yes, the beam can be corrected, in a pointer !! See "445LD with Anamorphic Prisms on a Jayrob DIY " When using prisms coated for the 445nm line, about 93% transmission can be acheived, so, if your output was 1075 mw...after prism correction your output will be 1000 mw. A drop in the bucket for power loss. Prisms will NOT give you a round spot !! They will give you a square box. They will give you 1.0 mRad divergence. For example...at 40 feet, your will see a square that is about 1/2" x 1/2". Much improved over a bar/line !!!

CDBEAM 777 @
Terrawattl Labs

 

[sarbanes]

Warning, run-on sentence below.


Is the beam from all or most high output
(>1<2W) 445nm's, so much easier to work
with, and, (by extension) much easier to properly
culminate than similarly powered 635nm's
(which are currently available now)?

NOT WITHSTANDING
the differences in wavelength (which can be
compensated for, to a degree)? Then WHY OH
WHY, pray tell, is Laser Glow selling high power 635nm's,
and explaining that there is nothing they can
do about basically projecting a huge focused square
50 feet from source? Unless, or course, the company
is run by Team Rocket, and composed of just like
3 or four people, who are really good at talking the
talk, but not so good when it comes to some fundamentals
when it comes to what they find to be somewhat
challenging optics which require just thinking outside the
box a tad?! I can think of two different solutions
just off the top of my head, to rectify their problems.
WOW!, I just do not know! Was sold a high power 635nm
hand held (running on C cells!) from them, only to have
it tested at nominal 658nm. I mean, WTF! Why would they
use a multi-mode 658nm, when, at this wavelength and power,
standard diodes are still available. Unless it is part of a
deception, I ask? Like (who in their right mind would use this
style diode - must be the real deal, 635nm). Of course, Team
Rocket was very embarrassed, and offered to take the laser
back, but not after wasting valuable time and money on my
end. It just seems childish and amateurish.

 

[InfinitusEquitas]

I'm curious about another effect I've noticed. I'll take a look more tonight, but figure someone on here has been it.

The appearance of a perfect small rectangle over a focused dot of a 445nm laser. I've only noticed this while wearing goggles, thought admittedly I haven't tried to look at the dot up close without goggles.

Has anyone seen this? I assume it's just an effect of the optics being used.

 

[daguin]

I'm curious about another effect I've noticed. I'll take a look more tonight, but figure someone on here has been it.

The appearance of a perfect small rectangle over a focused dot of a 445nm laser. I've only noticed this while wearing goggles, thought admittedly I haven't tried to look at the dot up close without goggles.

Has anyone seen this? I assume it's just an effect of the optics being used.

From the OP:

"Also, the higher output lenses may also show a "phantom square" (or other "noise") above the "spot." This is normal. There is always some spurious emission around the edge of the die. Your lens is just picking that up and focusing it along with the main beam."

The rectangle is the light being emitted around the entire face of the die. The laser beam is only emitted from one single spot on the face of the die.

Peace,
dave

 

[InfinitusEquitas]

Well this is embarrassing.

I read over your whole sticky a long while back, before I even had a 445nm, and didn't bother to reread the whole thing now...

Thank you for the answer.

 

[Gas Can]

What is causing this large "light spray" around the outsides of the beam? Is this just reflecting off the inside of the lens? It's a 445nm M140 w/ a 3 element glass lens and simple focus ring.

 

[DTR]

Yes the bat wings as I like to call them. ( - ) Are from some of the light hitting the edge of the lens housing and reflecting in that half moon shape on each side which is parallel with the raw bar like output of the diode.

 

[aryntha]

Just a note. I've found that an occasional 'square around the beam' that only occurs while focusing is actually back-reflections into the diode, and then back out. BE CAREFUL. I never let any of my 445s 'linger' in this state, as back reflections have ben known to kill diodes.

 

[qumefox]

Just a note. I've found that an occasional 'square around the beam' that only occurs while focusing is actually back-reflections into the diode, and then back out. BE CAREFUL. I never let any of my 445s 'linger' in this state, as back reflections have ben known to kill diodes.

You don't need to worry about that.. Why you make ask? It's because the same amount of light is getting reflected back to the diode regardless of where the focus position is.

What's going on here with the square being visible, is that the light reflecting off the lens back to the diode, is getting reflected yet again(off the face of the diode), and is going out the lens. It however is dim enough it's only visible when the focus is perfect.

So worrying about this is moot since even when it's not noticeably visible, the same amount of light is getting reflected off the lens back to the diode.

It is however useful for knowing when the focus is 'as good as it gets'.. since the square being visible and crisp, means the output face of the diode is right on the focal point of the lens.

 

[aryntha]

I'm not sure if we're talking about the same thing, Qume. When I first saw this was when I was screwing on the "clear" lens of my Arctic. At certain rotations, the 'square' would appear, and at others, it would not. That "lens" is just a glass disc (likely offset by an angle slightly) and performed no focusing function; I think the result was "backreflection was either there or it wasn't."

I've seen with some glass lenses an "ever-present image of the die" that varies with focus linearly, but I've also seen a "bright square" that appears and disappears at certain rotations of a lens. I think with the latter, you're seeing the presence or non-presence of a backreflection at all, and I think it'd likely be a good idea to avoid it?