I really like the Surefire TIR beam quality in my Lumamax LX2, and EB2 backup flashlights. They have a really good sized spot, usable spill and not really any artifacts in the spot or in the spot to spill transition. I have not found this beam quality from any other flashlights. I have tried the plastic TIR lenses in other flashlights and it didn’t come close.
I thought this beam quality had to do with the glass TIR lens. I may be uninformed but I haven’t read about people are using glass TIR lenses in custom builds, or even other manufacturers using them.
My question is, is it the glass TIR that is making the surefire beam quality so good?
If so, why aren’t other people using glass TIR lenses?
Or are people using them and I am just not aware of it?
So I did some searching online and I see that there is a place selling the borsilicate glass TIR lenses. Does anyone know about these or has anyone used them?
Never used a borosilicate glass lens, so can’t speak to that specifically. But I work with glass, mostly boro, and this sounds like a marketing thing to me.
For one there’s no such thing as “high borosilicate glass” like that one website claims. It’s boro or it’s not. There’s no “high” or “low”.
And I don’t believe flashlights get hot enough to make boro necessary. Most TIR lenses are made of plastic and they don’t melt. Regular glass has a softening point several hundred degrees above the plastic, where our little LEDs with their plastic domes would have already burned out, and Boro is several hundred degrees above that. What do you need a lens that can handle 1000°F on a flashlight for? Your battery wouldve been on fire a long time ago.
Some high powered incandescent lights do use boro, but I believe more use quartz fused glass if high temp resistance is necessary. It has much better optical transmission, can be much thinner, and it’s not just a little better at handling high temp and thermal shock it’s infinitely better. Regular soft glass can’t handle thermal shocks above like 100°F without cracking, boro can’t handle much more than 220°F. Meanwhile you can heat quartz-fused glass to 1500°F and throw it in bathtub full of ice and its doesn’t care.
Boro is more preferred when you need chemical resistance and the ability to handle a little flame. If you really want the best thermal properties and the best optical transmission you would go quartz.
But tbh it’s the “high borosilicate glass” statement that bothers me the most. I doubt that’s even boro. Sounds like an excuse to charge a few bucks extra.
Edit: btw that first link does look like legit boro, but i still don’t see the point in a flashlight.
Interesting info about the thermal properties of Borosilicate glass. But the optical clarity of the glass, light transmission, and minimal beam artifacts are where the borosilicate glass was supposed to be an improvement. So I was trying to compare those aspects to the plastic TIR’s.
I haven’t done direct testing or comparisons of plastic TIR vs Borosilicate Tir lens in the same platform to draw any conclusions. I have a couple Convoy S2+ flashlights that I tried different TIR lenses in, and the SMO / real spot TIR being the best certainly isn’t close to my lx2 or eb2 with the smooth RS real spot style boro TIR in terms of beam artifacts.
If quartz fused glass is clearer and has better optical transmission than Boro, wonder how RS real spot smooth TIR lenses made form quarts fused glass would perform in flashlights.
Maybe if they had just said “medium” it would have been more believable lol .
The difference in beam profile most likely has nothing to do with the glass versus plastic TIR. Your enthusiast level reflector-based light might have a different beam profile from a mini maglite, and that’s not because one reflector is metal, and the other plastic. It comes down to the exact model of TIR used, and how well it plays with a certain LED. Different TIRs are meant to produce different beam profiles.
As of why glass TIRs are not more common, they are much heavier and more expensive than their acrylic counterparts. I personally don’t yet see a single reason to prefer a glass TIR over an equivalent one made from acrylic.
Having a beam profile and tint that is useful for my application is the only function of a flashlight for me. If a Glass TIR provides a better beam profile with less artifacts for how I am using it, that might make it more functional for my application, that might justify the extra expense if that was actually what was making the improvement.
I am still on the lookout for budget lights with the features that I like and with a good beam quality. It is amazing how good they have gotten for the price now.
It may not be realistic for me to expect a budget light beam to be as clean as an enthusiast level light. But they are still pretty good. My lx2 and eb2 beam are fairly clean but not perfect either.
Oh I’m sure it would be better than plastic. I don’t know if it would be universally better, would probably vary. You’d want it to be precise. It’d be alot easier to be precise with plastic. There’s a lot of boro made in China that might be hit or miss.
Looks like those Auer ones in the first link are made with glass from Schott. Thats pretty much as good as it gets. Depending on who you ask they’re either the best out there or a very close 2nd. That’d be quality glass. Idk who would need that. Maybe in a lab where you’d want perfect consistency for measurement or in an operating room where you’d probably want the best CRI you can possibly get, or maybe some streetlights where you’d want it to hold up to the heat and the elements for decades. Idk how worthwhile it’d be to use in a flashlight, or if you’d even notice a difference. $25 a lens. Cost more than a whole Convoy. Would be a nice looking piece of glass tho.
Edit: forgot I have a couple HPS and metal halide light bulbs made of quartz glass. And some quartz glass rods and tubing. And I’ve got a bunch of Schott borosilicate glass I can shine a light through. And I’ve got flashlights.
Idk. Hold them and they feel different. The quartz is clear AF on the HPS bulbs. Crystal clear. The boro is solid. Doesnt break if it drops. But shine a light through them idk I can’t tell much of a difference. Just looks like light shining through glass. The thickness has way more of an impact.
I was thinking about getting a custom light made with a glass TIR lens, so I emailed Simon at Convoy and asked him about borosilicate glass TIR lenses, and he said:
“Borosilicate glass TIR lenses can not be found in China ,mainly because of the higher cost.”
Well simon would know. China mostly just makes the raw glass and ships it out to wherever to be made into whatever. But, counterpoint, there’s some here and some here. Probably not very good stuff tho.
Idk how much it would cost to get a custom optic made. Tens of thousands? Probably be easier to find a light that fits the lens
plastic tirs cant be used on uv light. would glass work? would you happen to have a uv light? if you could shine that through the glass tir you have, and see if the uv rays filter or not?
Regular glass blocks a bit, but it’s neglible. A small percentage. Enough to notice it side by side, but barely. A plastic TIR blocks almost all of it. The borosilicate glass I have blocks almost none of it.
The optic manufacturers offer a wide selection of materials from which they can make TIR lenses. There are PMMA formulations specifically intended for high transmission at UV wavelengths, generally in the UV-A range.
Looking at various wavelength distribution charts for PMMA materials, the UV transmission varies depending on the exact brand and formulation of material used.
The transmission of <400nm wavelengths will start to drop off at a certain point. Sometimes it is more of a gradual decline, sometimes it is a vertical cliff.
385nm and especially 395nm UV emitters are not far below the visible spectrum.
It is true that a typical PMMA TIR lens will likely have a significantly reduced transmission at 365nm.