AR Lens Evaluation

I’ve been looking for and have found a material for a new TIR L2M flashlight I’ve been working on too long.
I needed something thin (1mm) and because I already have considerable light loss from the TIR, I wanted to have the lens with the highest transmission as possible.
What I’ve found is a material that is commonly used on touch screens and mobile devices (the one’s that do not have the fragile glass screen)
It is an optical grade PMMA with AR coating on both sides, scratch resistant coating on both sides, a smudge resistant coating on one side and has a light transmittance of 98%.

I’ve tested AR glass before and have always been a little disappointed with the performance…I would expect to gain about 8% OTF but usually only got 2%.
Also, with AR glass, the coating seems easy to damage.

When I tested this PMMA material…again I expected about 8…I actually got 6…not too bad. Some of the performance may be due to the thinner material.
I checked the scratch resistance with steel wool…while I could scratch it…it wasn’t too easy.
The scratch resistant coating seems to make the AR coating more durable -even though the scratch resistant coating is underneath. I was told that the AR coating bonds to the Scratch coating better that to glass, so this increases the AR durability.
When I first installed it in a flashlight…I was shocked at the clarity. Looking straight into the light…I couldn’t see it at all…holding it at an angle, I could see the colors of the AR coating.
I fingerprinted a piece thoroughly and cleaned it with Windex…something I would never do with an AR lens…it cleaned up perfectly (the smudge resistant side did clean easier).
I tested it for heat stability by running it in a P60 at 3.8A for 30 minutes…no problem.
I could break the material by folding it, but mounted in a flashlight, this will never happen. It should be very hard to break from direct frontal impact and virtually impossible to break from side impact.

It’s a little pricey (about $200 per square foot), but I needed it so I ordered some…luckily the yield for small lenses was good, so it wasn’t crazy expensive per lens.

After my initial testing, I decided to add it to my website for the L2M TIR and also offer it for the other Solarforce L2 lights using a regular P60 drop in. The lens is laser cut a few mm larger that regular Solarforce glass. For proper fitment, the stock glass and sealing washer is removed and replaced with an ultra soft o-ring. Because the lens is cut a little large, it’s not compatible with Surefire and I haven’t checked the fit on any other P60 lights…but it does work in Solarforce.

I need testers:
I need 5 people with a Solarforce L2(P,T,M,N) to try it out and give me feedback on what you think about it…(must be CONUS).
Just reply ‘I want a piece’ or something to that effect. If you see that you are one of the first 5, just PM your address to me and I will send it out to you.
Within a week or so after receiving it, post your thoughts on the lens…Thanks

I will give it a shot! Thanks…

Solarforce L2T…

I'll give it a go. I can do some lumens measurements on it before/after, etc.

I'll try it out! I don't have a light meter, but I use my Solarforce every single day. Thanks.

I’ll give it a try.

L2N would love to try it in!

ReManG received his lens today, so everyone else should receive theirs soon.
One thing to look at, when the lens is mounted in a light and it’s on, look at it from a side angle…you will see that it still looks clear while a standard glass lens looks ‘hazy’ from internal reflections. This should not be any different than a good AR glass lens.
I know the lens will not beat plain glass for scratch resistance, but from the few tests I’ve done…the AR coating seems much more scuff resistant than the AR coating on glass. I’ve been disappointed with the durability of AR coatings on glass…I’ve actually polished off the outside coating on a few glass lenses because the coating was so scuffed up. This leaves AR just on the inside…which is half as good.

I’ve done some very intensive cleaning on one of the lenses, using windex, dry cleaning…evening hard dry cleaning with denim…it still looks good.

One correction…earlier, I said the ‘smudge resistant coating’ just makes fingerprints easier it clean. It actually reduces fingerprints by at least 50%…maybe more, so be sure to install the lens ‘green side in’ - ‘clear side out’. I’ve been making a small sharpie mark on the ‘green’ side very close to the outside edge (so that its covered by the o-ring), that way, if I ever take it out, I will know which way to install it.

I rotate a couple of Solarforce lights in my EDC class and really would like to know how this goes. I did not see it in time to chime in…

Matt

I received my lens yesterday, but I haven’t had too much time to play with it yet. However, I did compare it to the kaidomain a/r lenses that I have on my SF hosts and it is noticeably “clearer”. Maybe it is because the pflexpro lens is noticeably thinner but definitely it is visibly clearer than the kaidomain lens. Also to note, the a/r coating on the pflexpro is a purple hue vs. the kaidomain which is a blue hue. I’ll play with it more throughout this week and report back.

The reason the lens is 1mm thick is because I needed it for my L2M and L2P interchangeable head flashlights. I’m using a 26.5mm Carclo TIR mounted directly in the head. The TIR is very easy to scratch, so I wanted to have a protective lens on it, but I didn’t want to lose output. This special application is the reason the lenses are a larger diameter (and thinner) than the Solarforce stock lens.
I found, by using a soft o-ring, the larger, thinner lens fit perfectly into a L2x, so the lenses serve a dual purpose. Because of the expense of the material, having dual applications is a big plus for me.

I googled a similar product, the “Max Recommended Continuous Service Temperature” is 77-88 °C, it’s getting soft around 100 °C and the Thermal Cycling is only tested with 3 cycles (from –20 °C to 60 °C).
It’ll be interesting to see, if this material withstands the use in a high power flashlight - test it! :wink:

I will be testing with a good cell and one of Matt’s (Adventure Sports) high power dropins. She gets hot on high!

Take in consideration that it will be more critical if the lens is not 100% clean, the smudge resistant coating is a real plus in this context.

Got mine today - nice job in documenting the upgrade procedure. Got a nice L2P to try it out on - right now it's got a SS mild attack bezel, stock glass, pill with a XM-L2 T6 4C/Noctigon with a 2.1A Nanjg.

If anyone damages the lens performing some kind of destructive testing, I will send you another for more typical use.

I’m anxious to see if it holds up to the heat test…I only tested up to 3.8A since that’s the highest I run my P60s.

Too bad they don’t come in a D36 size, I could test them against my XHP70 and MT-G2 in my 900A and 962 Weapon lights? Pulling 9-10 amps on the glass reflectors?

Mine arrived today with some amazing instructions. I'll be doing some comparisons with the stock lens, generic AR lens, and the KD "HD" AR lens.

I have installed mine on the light I carry at work. I do not see how this is not a better lens than any of the glass ones. Especially in a light like the SF hosts that recess the lens. Most of the unintentional damage these lenses will see (pun intended) will be from cleaning.

I am running a 219A ~3000K at about 2A and there is minimal tint shift with this lens. I have a couple of blank P60 pills I need to put emitters and drivers into, so I should get to that this weekend hopefully. Running it side by side with another of the same emitters and a regular SF glass lens, I can see very little, if any, tint shift in a warm tint. I will do the same with some 2B tints I have for the empty P60 pills.

The instructions were thorough, as always with stuff Randy puts out.

The AR coating is much less visible than more “normal” AR coatings I have on other lenses.

The fact I got a lens shipped to me in a standard envelope is a big plus over glass lenses. Keeping a couple of spare lenses is a matter of a place to put them, not a storage issue to keep them from cracking.

Over the long term, I will report back here. First impression, great choice, great lens!

I’ve got a nice L2P host that needs a better lens. My hottest drop-in is a custom solid copper shell with 3x Nichia 219b on a FET that’ll hit 6 amps easy, probably more with a different battery, but that’s all I want to subject my beloved 219b’s to. I’ve been using it without a lens in front of the optic, but it does make me nervous about scratches and dirt and such. As soon as you start selling these lenses, I want one.

Just checking in before the holiday. The lens performs very well. There is some really minor, almost imperceptible, tint shift (toward green). Light transmission seems to be similar to the KD "HD" lens, possibly a bit better--this observation is highly subjective. Once installed, this AR lens produces a beautiful, incredibly deep dark purple reflection of objects from an angle. I've never owned a UCLp, but this lens has the deepest, darkest, purplest(?) reflection I've seen in any flashlight AR lens thus far. Very pretty just to look at. Also completely clear and invisible when looking at it directly.

I haven't tested for smudge and scratch resistance yet but will be doing so over the weekend. It's such a nice lens that I almost don't want to abuse it. But, it's all for science.