Lenses and beam cut-off

Flashlight Modding and DIY Parts
1

Hi everyone,

First, why have those pics gone ? I can’t see them… I left the link, just in case…

I had the project to build some lights, one for my bike and 2 (low/high) for the motorbike. I thought that carclo elliptical optics would be shaped enough so that the bike and low motorbike light would not blind oncoming traffic.

Well… I built the bike light (that I will review soon), with a triple (Nichia 219c 4000k 90+ CRI), and a 10510 carclo optic (triple elliptical). And the beam is not really “elliptical” it is more like a shaped potato, which fills me with fear for the future motorbike light.

I am wondering if any led/optic combo could be good enough to allow road-friendly beams. I am not opposed to the idea of blocking the tom of the beam with any opaque thing, but only if that is to block residual border light, not if it is to lose half the light emitted…

To be honest, according to carclo website, the 219c has one of the worst shape with the carclo 10510 (by that I means, all the other leds allow a flatter beam).

Other leds with a bigger single lens is way better. For instance, XHP35.2 HI with 26mm elliptical lens

It also exist other lenses, that are really interesting : carclo 12587. Upside down, the beam would be perfect, provided the cut-off is sharp enough…

And another one, from Ledil, the Strada-sq-fs, still with xhp35 hi

It is supposed to be use on light pole on the road, but the therorical cut-off seams very sharp. There is a lot of light near 60°, and nothing afterward. The light should be tilted, but is that a real problem ?

So… has anybody tried that ? Any advice, or any reason why this is dumb ? Would the xhp35 hi with a regular carclo elliptical be well enough cut-off ?
I know some topics talk about road-friendly beams, but :

- the market evolves, their could be new products, and new idea

  • I don’t want to go cutting other optics and all.

Thanks for reading !

2

Blocking the undesirable stray light with a physical cut-off is pretty standard in order to achieve absolute beam control. I would do that in this situation, with a duckbill type of guard above the optic.
Blocking the LED from being visible at all from oncoming traffic would be the most road friendly design, for example if the duckbill guard extended out quite a distance and had a slight downward angle to it, but this may be impractical to achieve.

Experiment with rudimentary setups until you find the right combination of LEDs, optics, and cutoff geometry, then design your housing.

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I’ve never played with these optics myself but browsing the Carclo emitter examples, it seems that the high intensity emitters are the ones giving the flatter beam profiles. High intensity meaning flat emitters without the dispersion dome. Some of the smaller domed emitters also give a little more flat/oval pattern compared to “larger” ones like the 219C (larger being the light emitting surface of the die…the phosphor area, not the overall size of the dome or the die package). Thinking about it I’m not sure why it has this effect exactly, but perhaps because most of the light is going straight into the “funnel” in the optic rather than throwing and mixing a bunch out to the sides (as domes will do).

I don’t remember if anyone happily or successfully dedomed the 219C but you might be able to slice the domes off to make them flat, taking it way down close to the phosphor surface. If you have extras and don’t mind the chance of failure, it might be something to try. That or perhaps buy some Osram flats or XPL-HI.

I think in one of the other bike light threads there were great comments about the requirements for mobile light beams…in Germany, not sure if that applies all over the EU.

Anyway, just an idea. By the way, if you don’t know already, the XHP-35 is a 12v emitter, not a regular 3v.

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To have the imgur images show up, you have to use the image link that has the “i” prefix, eg “i.imgur.com/4vqkJxb.png”

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Thanks Kenny, it’s all good now.

Yep, a little duckbill seems difficult to avoid, but I would like it to waste the least amount of light. Thus, the already good enough cut-off provided by the led/lens combo.
Given the spill of my 219c 10510, the duckbill should be quite big, so not really a good solution. Even though I can’t really other solution…
The light poll optic would need the whole lamp to be tilted in order to get an horizontal beam (not going to the sky I mean). This could make heat-sinking easier, and a simple little plate could make a great light block… I should draw that.

219c does not seems very easy to dedome. Plus I have only one spare, and my build is quite… a pain in the ass to disassembly. I thought about replacing with XP-L HI, but that’s the last thing I will try.
I would love to try many thing, but I can’t find a good shop in Europe…

The xhp35 is for the motorbike, 12V is too much for the bike (as it is dynamo powered). As you said, I will keep a small emitter area to get some throw. XP-L HI has better throw I red, but I would need a triple build to get the same power. 20 mm triple lens that will have a bad throw compared with a single 26mm…

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You cannot get good enough cut-off from the LED/lens combo. Any light that goes above the horizon line is basically wasted anyway, at least as it pertains to road illumination.

Here is a modern car headlight beam:

A video about the cut-off line and why it matters:

I suggest that you just buy existing products that are properly design for road use.