Outside my league… 
Yeah it’s a cool idea but very unaffordable for most people here.
I’m looking to get a university sponsorship to do some testing with this stuff, there have been tests done for lumen output already but what I want to know is the intensity that I can get.
If I can get 4k lumens from a 0.5mm spot then that will completely exceed all LEDs, and compete with some of the best short arc throwers that exist.
I updated the OP, the pic was gone, upgraded it:
The copper will be (a) heat pipe(s).
Very nice Jeroen. Curious how it will perform when done
So am i !!
I made some drawings to illustrate things (i also put it in the OP):
compared to a normal reflector:
A recoil seems (to me) be better in many ways.
The light straight from the LED (0°) only hits a small area, which is what you want because there’s not much of it, as you can see by the radiation diagram (blue).
You can see with a normal reflector much more light comes from the middle of the reflector, and when you want to reflect the rays at more than 45° from the emitter, you need to add a LOT of depth.
This is also true for the recoil reflector, but that adds more to the diameter.
It therefore seems pointless to me to make a recoil reflect more than 130°.
Even 120° seems good enough, but with an extra 10° you get just a bigger slice of the pie (the radiation diagram).
What i like about the recoil set up is that the focal distances (from emitter to reflector) don’t differ too much from eachother.
So it will have less of a corona with a different tint than the centre.
But you can change the scale of the parabola so that with the same diameter you still collect 180 degrees.
The difference is that the focal distance will be shorter, therefore causing more beam divergence.
Assuming the “front area is proportional to center beam intensity” that would mean that 5” 180 degree collecting parabola would collect more lumens, create a larger spot, and have the same intensity compared to a 5” 130 degree collecting parabola.
So it honestly depends on whether you want a tight beam and small spot, or the most lumen collection, because either way the intensity would be the same (according to what TheDriver explained to me)
Many Stanley automotive LED reflector are “half recoil”. The design make the most of the light produced by the LED without too much glare (very sharp cut off can be made). Not only Stanley does this, there are some aftermarket products such as Hella does similar setup too. But they utilize faceted reflectors to get the most uniform beam distribution required according to many international road regulations.
Yes.
But is it worthwhile?
With 130° there is not much spilled, just a small slice of the surface area of the radiation diagram.
I guess it’s like with aspheric lenses, but there is not much left beyond 130°, so i think it’s a little pointless to spend the reflector surface area on it.
I’m not a formulas and calculations buff, but when i visualized this with these drawings i thought 130° would be the best compromise between collection, diameter and focal distance.
Hella’s recoil:
Basically it’s halved reflectors with 2 separate light sources
Those Hellas look cool. :sunglasses:
But is it a thrower set up?
I can’t figure out exactly what’s going on in there…
Distributed thrower because it’s faceted.
This setup is becoming common in automotive these days. Easier heat management, less unwanted glare, and minimal obstruction to the beam. You can split your parabolic and get 2 XPL in the center pedestal without having to use obstructive heat pipe bridges
But wouldn’t that increase the spill dramatically?
(I guess i still don’t understand…)
Still no spill (before the ray hits the reflector first)
Ooh, a triple !
Looks like the LEDs have a primary optic so that it all hits the reflector surfaces (?).
Well, unlike with lenses, the reflector doesn’t need to be 0mm away in order to collect 180 degrees of light, so I would assume that the big intensity drop seen for low F number lenses probably wouldn’t exist if I redid all my spreadsheet calculations using a retro reflector instead of a lens.
I would still assume that the intensity is the same, so it doesn’t matter how many degrees is collects as long as it’s the same diameter.
You’re not really “spending the reflector surface area on it”, because the surface area of the reflector is almost the same whether it collects 130 or 180 degrees, the only thing that changes is the shape.
It would be another thing to say “spending surface area” if you were making the reflector bigger to collect the 180 degrees, but you’re not, you’re keeping the same diameter.
I personally prefer better efficiency, so as many lumens as possible (and brighter beam too) even if it makes a slightly bigger or less-sharp spot.
As far as I know, Hella doesn’t use any optics other than the reflector itself. Just bare LED
Here’s my idea for your parabolic setup:
I think this Spark design is considered as a semi quad recoil too with some spill allowed for peripheral vision. With some tweaking you can get something to begin with before start making any big reflector:
….or cast bigger replica reflector out of it
That’s not gonna work anyway, because the plano side will act as a reflector at those angles and the lens would have to be extremely bulbous and will suffer from internal reflections.
You will spend a larger percentage of the surface area on that tiny bit of extra light though.
I don’t think it’s worth it.
I like collecting as much as possible too, but it is a thrower, an über thrower even, so it would be nice to have a very tight beam.
(edit) …without it being huge in diameter…
There’s still an option perhaps to make it zoomable by moving the LED towards the reflector (or the reflector towards the LED) so that you can collect a little more, but with a divergent beam, like an aspheric zoomie.
But still i doubt if those few % extra collection is worthwhile and / or noticeable.
Yeah, i was thinking along those lines for a bicycle headlight, LED-ifying an old incan headlight more or less like that.
But it’s not gonna be an über thrower like that, but better for vehicle headlights.
There’s no point in having a light saber on a vehicle.