405nm AR glass lenses - fit AixiZ  FEELER

While I was experimenting with my violet laser and the glass window of the MXDL, I noticed both fluorescence and phosphorescence taking place (although with a REALLY short half-life time of just milliseconds)

This is most apparent when the laser is focused to about 2-4" and the lens is put in the beam waist.

Intrigued by this phenomenon, I tried more glass, glass lenses were the only other thing I have. None of the lenses had phosphorescence, but stronger fluorescence. Particularly, all lenses which consist of two lenses of different glass types cemented together (flint and crown glass I presume) have different amounts of fluorescence. The most convex lens always fluoresces the most. I also noticed that different such convex lenses also differ greatly among each other with respect to the amount of fluorescence. Most are weak yellow, one is strong orange. The least convex or concave part of the cemented lens also fluoresces, but barely.



Fluorescing glass obviously means a loss of power.

Do your lenses also fluoresce or are they completely fluorescence free?

BTW, my objective lens which I had previously put on top of the diode can and raised the power so much, also fluoresces quite strongly.

Re: 405nm AR glass lenses - fit AixiZ  FEELER

Yeah lets here it for manufacture 5 ;D ;D and lens 2 / 8 ;D ;D

Also my bond car / yugo comparisons last night may have been due to the cinema and then a few to many drinks , But I bet none of you can ever look at a yugo again without wondering just a bit

Thanks for all your hard work with these lenses Igor They are truley Brilliant, you should have no trouble getting the numbers you need for any group buy with these.

Re: 405nm AR glass lenses - fit AixiZ  FEELER

Zom-B: I doubt that the designers of the "Nichia lens" would use fluorescing glass for it. And since the power with the other lens is almost the same, they probably doesn't fluoresce much..

I will try....




Anyway, this fluorescence that happens within materials is a big part of the reason why many materials have such poor transmittance for UV.

But the transmittance data is known, and if the transmittance is high, the fluorescence obviously has to be low. I can try to do a measurement, but i will also ask for transmittance data for the lenses..

Sort of... When the laser is focused, it creates a waist which is a range where the beam seems smallest over the entire length. The waist is hitting the lens, probably not the tiniest spot. In fact, I just moved the lens forward/backward until the line was the thinnest.

I have yet to find a kind of glass that doesn't fluoresce.

Re: 405nm AR glass lenses - fit AixiZ  FEELER

Try F2 glass. That one has the highest transmittance for 405nm i have seen.. It shouldn't fluoresce noticably.. I have some F2 lenses here..


Otherwise, why does it matter? If the good lenses should fluoresce, would you want me to chuck them and continue searching?  :-/

Re: 405nm AR glass lenses - fit AixiZ  FEELER

Defects cause fluorescence, and defects are always present.  Glass is a funky one, since the amorphous nature of it kind of obscures the whole picture.  (You'll have to forgive me for the very hand-wavy explanation, glasses are not my forte and are pretty complicated).  But even if you have the most pure substance on earth, you'll still have vacancies even if you manage to completely purify it.  (That's thermodynamics: even if your material is a completely pure crystal of 1 element, it will ALWAYS have a minimum free energy at a point where it has vacancies within it, unless you're at absolute zero, which can't happen).  Since we can't even completely purify glass, you'll always have vacancies AND other point defects, such as substitutions or interstitials.  All these defects can lead to fluorescence, and they're always going to be there.  It's just a matter of how much is going to be there.  Optical elements of high quality should be pretty low on impurities in general, but vacancies and other defects will never be zero.

-----------------

But that brings up an interesting question that no one has to respond to, just rhetorical; how do you quantify a vacancy in a glass, which by definition has no long-range order?  Ie, if there's no defined place where an atom should be, how do you define when an atom is missing from that place that isn't defined?  It has to be some kind of vacancy-like defect or something more complicated; it's certainly not simple.  My head hurts.

Re: 405nm AR glass lenses - fit AixiZ  FEELER

Haha... Take an aspirin..

Anyway, for me the question is very simple... Why does it matter?

I'm not gonna go look for more lenses. I know where to get better lenses (Manufacturer #4), but like i mentioned, they cost 40 EURO each in quantities of 500!

The lenses i have here are actually direct substitutes for the expensive lenses from manufacturer #4.. And the quality is not much different.

In the worst case, transmittance is >95%. That's the lens as a whole (coatings and all). That's the same transmittance the Meredith lens has for reds.


These lenses are the highest quality we will hopefully be able to afford. I have lenses made of materials that have a better theoretical transmittance, but their quality is so poor, that it's just horrible. When i was testing lenses 4-6 i didn't even want to post about it, that's how bad it was - i didn't want to make anyone worried, because i knew i had good ones on the way..


I finally have good lenses. I am tired. I'm not gonna go look for better ones, cos we couldn't afford them anyway, so screw fluorescence.
My head hurts too...

I couldn't possibly ask of you to search for better lenses after all that you have invested here. It would just be an insignificant note for future research. (When researching a topic, you always end up with more questions thatn you started with, but you have to choose your path and walk it to the end before deciding a new path)

Re: 405nm AR glass lenses - fit AixiZ  FEELER

I understand.. I'm just really exhausted..


Anyway, there is some minimal fluorescence.. But nothing major. The minimal transmittance of the lens as a whole (with coating) is at least 95%.

So theoretically a better material could bump the power higher. But the better material lenses sucked. But i will ask my manufacturer for actual transmittance data.


But i know for sure, that the lens designed specifically for blu Nichia diodes is a GOOD lens for blu diodes!

I've been in contact with the manufactureer that makes lenses for ThorLabs. Unfortunatelly the prices they quoted me were same or higher than thorlabs! And they actually wanted to send two representatives here! They probably think i'm a huge corporation with a special R&D department, a manufacturing facility and a separat floor in the building just for management. ;D (i kinda abused my company to get answers faster)

I did actually want to buy one or two of their lenses for testing, but luckily just after that i found the latest manufacturer... I ordered lenses from them, without even realizing, that the lenses i ordered are basically the same lenses i asked quotes for from the expensive manufactureer...


Anyway, i will capture and post some data on the lenses i have here now...

Re: 405nm AR glass lenses - fit AixiZ  FEELER

I would like a nice clean dot even if less power is coming out. I would be in for v7.
If you spent $70 on a host wouldn't you want a perfect beam? I don't know if I want to build it before the lens comes. The acrylic lens will make it not only lower powered but it definitely wouldn't last as long. This lens would just take so much stress off of my 4x diode, it would help it live longer even at higher powers.

Re: 405nm AR glass lenses - fit AixiZ  FEELER

Hi Igor,
my personal opinion is that you have already done a great work: you have found a good manufacturer, v7 and v8 lenses show to be both good lenses, and the v8 gives an average 30% increase of the output power than the Aixiz acrylic one.
For me it is more that enough for now! I do not understand Artix objection, I have not been able to read that this v8 lens has some problem . So, please, complete this exceptional improvement with a good nut+spring and when you'll be ready pls start a new GB to collect orders and money!

Re: 405nm AR glass lenses - fit AixiZ  FEELER

FrancoRob said:

I do not understand Artix objection, I have not been able to read that this v8 lens has some problem .

Click to expand...

v8 doesn't have any problems. It lets more light through and the beam is smaller. It lets everything through so the outer parts of the dot is visible. What I want is a perfect dot. It does block some, but overall, its perfect! I don't think the differences would be all that big. So 10mW or so loss doesn't matter to me!

I spent $70 on a blue and black anodized Kryton groove. It looks awesome!

Re: 405nm AR glass lenses - fit AixiZ  FEELER

my head hurts just reading all the jabber back and forth!!  

I'm all for v8 and v7.  These seem to be the best of the best so far and without going any further (can't kill the horse that's carried us this far) we stop and go with what we've got.  The potential of seeing 150mw from a 803t at much lower current levels has me very excited and I've been saving a true 6x diode specifically for a special Kryton I made for myself.  You can be assured it's going to have an IgorT lens and is going to KICK ASS!

Thanks Igor for your work.  I've heard and seen it in my threads before and you blush and say to yourself.  Bah, it was nothing.  It is everything.  You have sacrified and driven yourself to find a great lens and you have done so.  It could have been done by someone else eventually but YOU did it.  YOU deserve the credit.  YOU deserve the accalaides.

THANKS!!
Ken

Now, start the GB thread, and watch those numbers SKYROCKET!!!!

Re: 405nm AR glass lenses - fit AixiZ  FEELER

Artix:
Ok, I have gone back to the reply #671 and I've seen at what you refer:

IgorT said:

So we are now actually at lens 7-9, and v7 (Lens #1) & v8 (Lens #2) are the best so far.... The latter increasing the power the most.

We will go with the 8th custom lens attempt, for max power and thinnest beam. But i am hoping i can also order some of the first lens, because it makes a "cleaner" spot, due to the medium NA clipping the ugly edges of the fast axis, and creates a "fatter" beam..

Lens #2 will bring out all there is, so the spot shape will depend ONLY on the diode output shape. It's the only way to get all the power out, and means, that diodes with a weird shape output will create weird shape spots... As diodes get better, so will the spots..

Click to expand...

Well, I believe that a picture of both the v7 and v8 spots (when Igor will be in condition to show them to us) will be surely helpful to choose the preferred lens. I hope that in the data that Igor will capture and post, there will be divergence data too....
That is, if the spot is smaller that the Aixiz one, who cares of the "ugly edges of the fast axis"? If the spot is similar or larger, you can be right in choosing the v7 lens...

Re: 405nm AR glass lenses - fit AixiZ  FEELER

About the divergence, I read that generally the bigger the beam, the better the divergence. But still, we need some pictures of the two lenses, side by side beamshots and some pictures of the dots.

Re: 405nm AR glass lenses - fit AixiZ  FEELER

i understand the point about "does this lens fluorescence?" completely! same as "what does the lens' coating look like, green or violet like prescription glasses?". no, it wont make me buy less lenses, nor would i ask to search for other, "better" lenses. this lens is as far as we will come, for this price, for the next years i bet. pretty close to perfect, i think everyone agrees!
still, curiosity, which is what brought us here, not? ;-)

clipping the beam/dot/lens to get a nicer dot with a small sacrifice in power: sure! get this high-NA lens, and reduce the NA! either change the lens' focallength (kidding), or reduce its diameter. a black (anodised) thin sheet of alu (or other metal) with a hole smaller than those 7mm of the lens, perhaps 5mm, between the diode and the lens, as close to the lens as possible. heck, if enough people are interested (someone calculate the loss in power from this?) we could let these be custom-made as well, with only cents for each, in bulk!

i think i will order somewhere around 10 lenses. i would love to order around 10 housings (which are verified to fit) and a bag of those "pinhole" metaldiscs from IgorT all at once! oh, and some spare/empty extra nuts as well

another thought: IgorT, you invested *so* much time and money into this, and mentioned your 'other' life is demanding as well currently. if you ask, i bet some other people will gladly get the nuts (and pinhole) designed and ordered for you, for us!

just some thoughts..

manuel, excited all the time in this thread!