2mm ZWB2 filter tested (visible light blocking filter suitable for 365nm UV flashlights)

[pirateo40]

@djozz

I’m around
That is a lot of improvement, so reflection on the glass surfaces from UV is worse than with white light, and so there is more to fix for the AR coating!

Nice of Simon that he is willing to do that, I’m certainly in for some of those if the price is reasonable, AR-coated ZWB2 filters should look cool too btw.

He quoted $3.83/ea which is the same price he sells two of the non-coated filters for now. He says they need to be produced (manufactured) and will get back to me. Will keep you informed

[pirateo40]

Here’s a graph showing one company’s projected improvement

[CRX]

That would be cool, what would be phenomenal would be to get some 12mm & 10mm sizes made too.

[ImA4Wheelr]

^

And SRK/Maglite size. I want to make a UV multi-emitter.

Also, interested in the A/R coating aspect, but different sizes more.

[LightRider]

I’m interested in a couple at least. I have two Nichia NVSU233A-U365 1030mW chips on the way right now. My first uv emitters so I’m trying not to get too excited.

[gravelmonkey]

Anyone found a source for larger than 20.5mm diameter lenses? I want to build a multi-emmiter light or even maybe a 365nm C8, because, why not

[Lightbringer]

Looked on AX, only sheets for a few hunnert bux each.

I wanted some for a ’501 or ’502, ’though yeah, a C8 would be nice!

[djozz]

Yes,on aliexpress there is a mix of offers with random thickness and diameter, sometimes more offers, sometimes hardly any. Usually tens of dollars for anything more than 25mm.

[d_t_a]

Pardon a dumb question. I ordered a set (2pcs) of ZWB2 filters from Simon’s Convoy store in AliExpress and it just arrived a few days ago. I’m wondering when I place the ZWB2 filter inside the Convoy S2+ UV Nichia flashlight, can I place it behind the existing plain glass lens (which is what I just did — so it has a plain glass lens in front, and the ZWB2 filter just behind it), or do I need to remove the plain glass lens altogether (ie. only the ZWB2 filter)?

When shining some other light on the ZWB2 filter, it looks like it has concentric circles/rings, though I don’t notice the concentric rings when using the Convoy UV w/ ZWB2 flashlight…

[djozz]

Don’t know about the circles but I always replaced the glass with the filter.

[Lightbringer]

@d_t_a

When shining some other light on the ZWB2 filter, it looks like it has concentric circles/rings, though I don’t notice the concentric rings when using the Convoy UV w/ ZWB2 flashlight…

Yeah, when 2 pieces of glass get close enough that there’s a very small air-gap, you get funky optical properties. Some places would be in contact, some places would have a clear air-gap, others would be in that twilight zone in-between where it’d essentially be a vacuum (ie, other than maybe H₂, no molecules would be able to fit.

So what you’re seeing is a sort of standing-wave of the 2 distinctly different interfaces: glass–glass, glass–air, and glass–vacuum, and the different refractive funkiness of each zone.

That’s why I don’t even like to keep the original glass when refitting with a TIR. Weird things can happen.

—

Oh, wait a sec… you mean just the nekkid ZWB2 filter and no other glass on/under it? Hmm, never really noticed that. Will have to look.

[djozz]

^ ah, now I see what rings were meant (they are called Newton rings, an interference effect between layers close to each other, close to parallel but not exact.)

[Lightbringer]

@djozz

^ ah, now I see what rings were meant (they are called Newton rings, an interference effect between layers close to each other, close to parallel but not exact.)

Ah, good. I was hoping someone’d remember what they were called. I was drawing a blank.

[d_t_a]

@djozz

^ ah, now I see what rings were meant (they are called Newton rings, an interference effect between layers close to each other, close to parallel but not exact.)

Learned something new today. Yes, Newton rings are indeed what I’m seeing.

Newton rings — from Wikipedia —

The pattern is created by placing a very slightly convex curved glass on an optical flat glass. The two pieces of glass make contact only at the center, at other points there is a slight air gap between the two surfaces, increasing with radial distance from the center.“

Thus by placing 2 pieces of glass (the non-AR-coated glass lens and the ZWB2 filter) close together, there is indeed an air-gap between them that causes these Newton rings… I wonder which one is the slightly convex curved glass — the plain glass lens or the ZWB2 filter — more likely the ZWB2 filter?

[Spiderlight]

Is the coated version still available somewhere?

[djozz]

@Spiderlight

Is the coated version still available somewhere?

I do not understand, the coated version of what do you mean? (ZWB2 filters as far as I know are not coated).

[Spiderlight]

@djozz

@Spiderlight

Is the coated version still available somewhere?

I do not understand, the coated version of what do you mean? (ZWB2 filters as far as I know are not coated).

There was a coated version mentioned above but I don’t know if it was released.

[djozz]

@Spiderlight

@djozz

@Spiderlight

Is the coated version still available somewhere?

I do not understand, the coated version of what do you mean? (ZWB2 filters as far as I know are not coated).

There was a coated version mentioned above but I don’t know if it was released.

Ah sorry, I see, I should have read some posts back, the discussion is from last year and apparently I’m so senile already that I totally forgot.

I guess Simon never went on with it and pirate stopped bugging him about it. It is not in his store at least.

[Spiderlight]

@djozz

Ah sorry, I see, I should have read some posts back, the discussion is from last year and apparently I’m so senile already that I totally forgot.

I guess Simon never went on with it and pirate stopped bugging him about it. It is not in his store at least.

Ah that’s sad. The coated version would have been an even better addition than the non coated filter I think.

[pirateo40]

Just reread this post - forgot to update -sorry. Upon further investigation I was told that AR coatings are not really efficient for UVA and result in a significant transmission loss, so I just dropped it (sadly don’t remember the details). Of course I’m sure there are specialty houses which can create very efficient coatings, but at a very inefficient price (I was quote a couple hundred for one piece, and a setup charge as I remember).