Does anyone know of a source for high quality plastic lenses around 60mm diameter? I’m looking to make a lightweight lens thrower so I’m looking at alternatives to glass. Kaidomain has a lot of glass lenses around this size, but no plastic lenses.
https://www.fasttech.com/search?convex%20lens
Not sure how “around” you need to be for 60mm, but go crazy…
Thanks I had actually not checked them yet, but it turns out they don’t have what I want. They have a 48mm acrylic lens but I want 60-63mm.
?? 
not cheap though…
(edit) aha, that’s 10 pieces… :weary:
Here you go:
Very cheap actually.
Wonder if it’s any good…
Flashlightlenses.com they can custom make a lense for you if need be. And a few different materials to choose from
Mtnelectronics it’s about $10! It’s a very tight beam lens. 60mm 10158 Carclo - 60mm Ultra Narrow Catadioptric
Yajiamei Optics Co, Ltd. Got a lens from them a couple of months ago, quite pleased.
Cheers ^:)
Y’mean like 60.3mm?
Glass, yeah, but is plastic critical?
It’s glass, so it weighs the same as a similar plano-convex lens.
It’s also not as tight as a 60mm plano-convex lens, but it does have much higher lumen efficiency since it collects 100% of the light from the LED.
Curious… what are the advantages of a non-glass aspheric? Is one material more efficient than another?
I guess weight reduction would be the obvious one…??
It’s cheaper.
Glass pretty much always has higher transmittance and is more expensive.
Often the plastic ones are better shaped.
Because they’re all cast lenses, not milled.
Apparently glass has a stronger mind of its own as to in what shape it will solidify.
Production is expensive because glass needs to be scorching hot to melt and takes longer to cool down as a consequence.
If you go to a proper optics store like edmund optics you will see the glass ones are almost always better shaped.
Unless you compare cheap glass ones to precision plastic ones which are like $300 for a 30mm lens.
Thanks for the finds, everyone.
I bought one of those catadioptic optics from mtnelectronics to use for this light. It is glass, but it is thin and not very heavy. Unfortunately preliminary testing showed it does not focus right with the dedomed LEDs I used. Not sure if it is just my sample or not.
The goals for this light were to be compact and lightweight enough to easily carry using a belt clip, but have greater than 300Kcd, something like a bigger C8. I bought a Fandyfire SP02 and was intending to mod it with a fresnel lens, similar to my C8 fresnel lens mod. The only suitable fresnel lens had a focal length ~1.5cm longer than the stock MCPCB-to-glass distance, so I had to extend this distance somehow. I made a new pill to push the MCPCB farther into the light and machined a PVC bezel to extend the length. I’m also using a precollimator lens to increase the light collection efficiency.
The bezel OD is 70mm, and it has 60mm active lens diameter. With an old-style dedomed XPG2 it does ~350Kcd. This is pretty good, but based on the lens area I was expecting more like 450Kcd. I think the fresnel lens is limiting the throw.
This is why I was looking into the possibility of a plastic aspheric lens, to get that extra 100Kcd. But I’m not sure I will end up changing the lens because weight and compactness would suffer some. As it is now it weighs 230g with an 18650 cell. For some comparison, a UF1504 with 18650 cell weighs 486g, too heavy and bulky to easily put on a belt clip. Its glass lens weighs ~100g by itself. My fresnel mod C8 with cell weighs 182g and does 166Kcd.
I was comparing moulded budget glass and plastic lenses, typically used for LEDs.
It’s strange though, that decent slide projector collimation lenses often aren’t that good for LEDs either.
It seems it’s always a bit of a gamble if your lens will perform well with an LED.
(at least in my experience)
Apparently there’s something wrong with those.
The reports i read all say the same thing: It doesn’t focus right.
And that’s a shame, because the concept should work very well.
I think it’s still pretty good, it makes a nice round spot with little spill without taking up the space that a regular lens or reflector would.
The spot is large though, so not good for throw, just short or medium distance work.
If the LED could be inserted further into the catadioptric then it might be able to fully focus, but with MCPBCs stuck on the back it’s impossible to test.
I missed this comment.
Interesting.
Does it do better with a dedomed LED?
The Catodioptic from Richard is not glass, it’s a Carclo 10158 and is plastic. I have one right here beside me. No fresnel either. It’s a shallow TIR with a mirrored coated on the back side such that it’s sort of a combination reflector, TIR.
Edit: Looking at the Carclo spec sheet, this optic has it’s best efficiency (still a dismal 69.6%) with a Seoul P4 emitter at 139.6 cd/lumen. Everything else they list works pretty miserably in it that I can see.
Edit II: The Ledil Seanna utilizes an TIR to gather the light and a Fresnel on top to collimate it’s beam for outstanding downrange performance, it’s 153mm diameter and somewhat costly. I have an XP-L HI under mine and it’s making over 600Kcd attached to a Courui D01 battery tube/pill section.