AR Lens coatings - just a gimmick?

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turboBB
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AR Lens coatings - just a gimmick?

Since I had received a TN31 XM-L2 without AR coating on the lens, I decided to conduct an investigation to see if the AR coating truly helps bring out more lumens or not by comparing it with the original coated lens. Includes measurements on my PVC LMD.


This is by no means a comprehensive vid on the topic since there are other variables (types of glass, coating, output level, etc.) but should give a general indication on its effectiveness.

Tim

Edited by: turboBB on 04/03/2015 - 18:41
totilde
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I can’t see the video

Mooooooo

kronological
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Doesn’t work for me either.

No one, after lighting a lamp, puts it away in a cellar nor under a basket, but on the lampstand, so that those who enter may see the light.

My Reviews: Ma

turboBB
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Sorry about that guys, should be fixed now.

kronological
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Informative video.

Definitely depends on the quality of the AR glass/coating. I remember when we did the BLF-X6-SE, an early sample AR lens actually had less lumens than a standard lens. The final lens did perform better.

No one, after lighting a lamp, puts it away in a cellar nor under a basket, but on the lampstand, so that those who enter may see the light.

My Reviews: Ma

totilde
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It is!
thanks for the info. did you measure without any glass?

Mooooooo

turboBB
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Thx guys and doh, sorry forgot to measure w/out the glass but I've done it in the past and that makes much more of a difference (I think on the order of >~5%). Indeed the type and quality of AR coatings make a huge difference. I think it's generally accepted that good ones can yield a gain of ~2-3%

ImA4Wheelr
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Just looking at the cover to the video, it appears there is a lot more surface area around the head of the light to not reflect (in case of AR coated lens) light back down the light tube.  There seems to be a whole lot of variables that causes much confusion.  I tried to compare some uncoated to coated lenses using the same host in this thread.  Overall, it AR coating seemed to make a difference, but I'm sure there is much I didn't consider in it.

DB Custom
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I once built a Courui D01 for a thrower, was quite pleased with the 338Kcd I got from it. Then I got in the UCLp from flashlightlens.com. No other changes, just the lens swap, netted me 365Kcd. Needless to say, I was very happy with that $7 purchase. Wink

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Yea, lenses from flashlightlens.com are real nice and the output increases have been confirmed. Definitely a worthwhile upgrade from the stock plastic mag lens…

DB Custom
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I think my modified Olight Intimidator went from 610Kcd to 622Kcd. Then a change to the battery supply got me up to 645Kcd. That big 95mm UCLp is incredible! Invisible, gives the Illumination Machines Lum 5-90 reflector a clear view. Smile

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Agree with other views, it largely depend on the quality of the coating if everything else being same.

I’ve only measured regular (cheap cheap) reflective glass vs no glass, huge difference, >10% in kcd drop in my T13, so your initial lens quality also counts when comparing vs AR.

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I’m in the process of building another D01 for a friend, & have bought a few cheap camera filter lenses, which I’m planning on doing a back-to-back comparison for throw readings.

I should have it done tomorrow.

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Over here also achieves improvements between 8% to 10% in kcds in my mods with AR multilayer glass lens regarding original lenses without any treatment Smile

Sorry for my bad English…

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DBCstm wrote:
I think my modified Olight Intimidator went from 610Kcd to 622Kcd. Then a change to the battery supply got me up to 645Kcd. That big 95mm UCLp is incredible! Invisible, gives the Illumination Machines Lum 5-90 reflector a clear view. Smile

if you don’t mind me asking, what mods did you do to your Intimidator to get those levels of kcd? and what model was it? ( SR90, 92, 96, etc.

That Canadian flashlight guy & Lantern Guru -Den / DBSARlight

turboBB
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Thx for the informative follow ups. I have a feeling that the differences netted measured as lumens in my PVC LMD will be lower than measuring throw. Will do a beam throw comparo in the future and remember to include measurements without glass at all.

Again this was just a sample size of one so would be interesting to test additional samples in the future. Looks like a visit to flashlightlens.com is in my future. Laughing

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DBSAR wrote:
DBCstm wrote:
I think my modified Olight Intimidator went from 610Kcd to 622Kcd. Then a change to the battery supply got me up to 645Kcd. That big 95mm UCLp is incredible! Invisible, gives the Illumination Machines Lum 5-90 reflector a clear view. Smile

if you don’t mind me asking, what mods did you do to your Intimidator to get those levels of kcd? and what model was it? ( SR90, 92, 96, etc.

I would also like to know Shocked

Sorry for my bad English…

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Well, the most annoying thing about AR coated glass lens is that the light gets kinda green tint after emitter dedoming, especialy if the emitter is 5700k and under
I had my Javelot default emitter replaced for that reason

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Mitko wrote:
Well, the most annoying thing about AR coated glass lens is that the light gets kinda green tint

Even without dedoming the LED.
That’s why I don’t like AR Coated lenses. I buy 4C or 3B XM-Ls because of the good tint – and then a lens destroys it Sad

Not for me… I preferably have a bit less lumens but a nice light color than the other way around.

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L4M4 wrote:
Mitko wrote:
Well, the most annoying thing about AR coated glass lens is that the light gets kinda green tint

Even without dedoming the LED.
That’s why I don’t like AR Coated lenses. I buy 4C or 3B XM-Ls because of the good tint – and then a lens destroys it Sad

Not for me… I preferably have a bit less lumens but a nice light color than the other way around.


Why not buy a LED that tends more toward red (something with “A” or “D” tint) for use in lights that use AR coated lenses? If you really don’t like the green tint, why are you buying green tinted emitters? Wink

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DavidEF wrote:
L4M4 wrote:
Mitko wrote:
Well, the most annoying thing about AR coated glass lens is that the light gets kinda green tint
Even without dedoming the LED. That's why I don't like AR Coated lenses. I buy 4C or 3B XM-Ls because of the good tint - and then a lens destroys it Sad Not for me... I preferably have a bit less lumens but a nice light color than the other way around.
Why not buy a LED that tends more toward red (something with "A" or "D" tint) for use in lights that use AR coated lenses? If you really don't like the green tint, why are you buying green tinted emitters? ;)

The A and D are more towards pink than red, but I would ask the same anyway. Most B and C have green tendencies at their core due to their Y axis placement. The easier way to expose that green it is to compare side by side with something equivalent from A or D, whoever the famous "dual tint" of the CREE XM-L LEDs can be more or less visible based on the shape and size of the reflector.

DB Custom
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De-domed XM-L2 U2 1A and modified driver. The driver makes too many amps for the XM-L, so I removed their “sense resistor” and stacked resistors to get 6.6A to the emitter. *Olight used a bar, like in a DMM, for resistance.

I put a UCL or UCLp in every light that I favor. Smile The UCL glass lens in a MiniMag Light really disappears, well, ok, it does that in most all of em. Without reflections from external light sources the emitter and reflector look really awesome when viewing the light. Wink

I haven’t bought other AR lenses, can’t say I know what y’all are referring to about the green cast…haven’t noticed that in any of mine but I HAVE replaced Olight and other brand name AR lenses that had a yellow tint to the glass. Lay it on white typing paper. Can you see it? You have to be careful where you put down an UCL lens as it’ll get lost very easily!

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The green cast thing is an interesting observation. not something i’ve noticed myself with the Ucl lenses.
But it makes sense in theory since the coating’s purple/bluish cast would indicate it is still reflecting those colours to some extent while letting the green/yellow/red through almost completely unhindered?

turboBB
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LinusHofmann wrote:
The green cast thing is an interesting observation. not something i've noticed myself with the Ucl lenses. But it makes sense in theory since the coating's purple/bluish cast would indicate it is still reflecting those colours to some extent while letting the green/yellow/red through almost completely unhindered?

Correct, when you look at coatings and see a particular color, that's the wavelength that the coating is "canceling" out. AR coatings have no color, here's a great article on the topic:

http://rick_oleson.tripod.com/index-166.html

I should also add that in my testing, I was trying to see the differences in tint with and without the coating (purple) and couldn't find anything discernible. This wasn't merely just observing it with my eyes but I videotaped it and then compared still frames. However, I believe a coating aimed at green wavelengths would have made a difference. 

locusto03
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Hikelite wrote:

The A and D are more towards pink than red, but I would ask the same anyway. Most B and C have green tendencies at their core due to their Y axis placement. The easier way to expose that green it is to compare side by side with something equivalent from A or D, whoever the famous "dual tint" of the CREE XM-L LEDs can be more or less visible based on the shape and size of the reflector.

This would explain my dislike of the tint in the nw blf X6. I've been wondering why the color seems really pale and greenish.

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As an experiment, try shining the light around with the lens removed…see if it still gives that greenish cast you’re not liking. Curious to see if it makes any difference.

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DBCstm wrote:
As an experiment, try shining the light around with the lens removed...see if it still gives that greenish cast you're not liking. Curious to see if it makes any difference.

I just tried it. The AR lens of the BLF X6 does indeed cause the beam to look greener than without. Now I wonder why there haven't been flashlight AR lenses that look green instead of the typical blue/purple/pink (at least I haven't seen any). It might make for a more pleasant overall tint.

 

Edit: I'm curious if the stock non-AR lens changes the color at all. Unfortunately, I don't have one to test.

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locusto03 wrote:
Now I wonder why there haven’t been flashlight AR lenses that look green instead of the typical blue/purple/pink (at least I haven’t seen any). It might make for a more pleasant overall tint.

Read Turbo’s link
turboBB wrote:
AR coatings have no color, here’s a great article on the topic:

http://rick_oleson.tripod.com/index-166.html


TL;DR
Single layer AR coatings target the middle of the visible light spectrum (green). This gives the highest light transmission throughout the visible light spectrum. But it causes slightly more transmission of the center target (green) then the rest. It also gives the lens a purple-ish reflection off the surface.

There isn’t anything they can do about it with single layer AR. Try an led tint that has less green to begin with. UCL lenses are advertised multilayer and supported by people saying it doesn’t have any green tint.

locusto03
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I'm guilty of not always reading everything before posting, so thanks for the clarification.  I've gone over turboBB's link and think I kind of understand it now.  I incorrectly assumed they could simply target the greenish blue or red part of the spectrum with a single-layer AR coating, but it appears that would negate the purpose of the coating in the first place, as it wouldn't affect enough of the visible part of the spectrum.

It seems like UCL is the way to go.  I'll be picking up some UCLp's for my "better" builds and sticking with uncoated lenses for the rest.  Even if the single-layer AR lenses do increase output, the shift toward green simply isn't worth it for me.  It's actually the primary reason I haven't been using the BLF X6 much.  An emitter swap does seem tempting, but I'm hesitant to mod the light after all the work that various members put into it.

Edit: Terminology.

DB Custom
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locusto03, look at it like this… when you order food at a restaurant a chef has gone to a great deal of trouble to prepare your meal, correct? Then when you get it at the table, you add salt and pepper to taste, do you not? Modifying the X6 would be like adding salt to that dish, tweaking it to your taste. Smile

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Read Turbo’s link

turboBB wrote:
AR coatings have no color, here’s a great article on the topic:

http://rick_oleson.tripod.com/index-166.html


TL;DR

+1

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