Future development of the maximum luminance of LEDs

You need to differentiate between hotspot and corona (“coma”). Deep reflectors (at the same outside diameter and same size LED) make the actual hotspot with maximum intensity smaller and the corona surrounding it bigger. The corona also has a high intensity, much higher than the spill, but noticeably lower than the hotspot itself. This fills in the dark gap between the hotspot and the spill when shining the light into the distance. This can create a more practical beam.

Armytek uses very deep reflectors. You can compare beamshots of them with those of lights from other manufacturers.

I can’t stand the armytek hotspot within a hotspot effect from their deep reflectors myself.

Same goes for, for instance, the Thrunite TN31.
Deep reflector, small hotspot, large corona.
Take out the XM-L2 and replace with a (decomed) XP G2 and you get an even smaller hotspot and an even bigger corona

The large corona makes these intense hotspot throwers more usable because you can still illuminate something next to the hotspot.

Example of a thrower with shallower reflector and thus larger hotspot (but almost no corona): Olight M2X Javelot and Amutorch JM07.

No one can accuse me of having in dept knowledge of the physics behind it all; i draw my knowledge from field experience.
And I like to read a lot about things I like :wink:

Cheers,
Nico

I also like that shallow reflectors have a wider spill beam, making for slightly better illumination of immediate surroundings. I value that quite a bit as well.

Thank you for the helpful post.

The Osram Black Flat HWQP might be a bit better now .

Thanks for this, really gives some food for thought. :slight_smile:

Difference between 100mm and 120mm depth with 120mm width (iirc)

With a shallower reflector, the focal distances are always larger, thus more throw.
Yeah you have a little more / wider spill, but i don’t think that makes too much of a difference for the throw.

Here you can see how little more depth adds:

What are you trying to show us with your pictures?

Basically that a less deep reflector is better for throw, when the diameter is fixed.
Focal distances are longer with less deep reflector, because it’s a larger parabola than a deep one.
Added depth doesn’t add much light hitting the reflector.
Your drawing is a bit misleading i.m.h.o. because it ignores the radiation pattern of the LED.

Enderman’s calculators claim otherwise.

All domeless LEDs have generally the same radation pattern. They are basically lambertion emitters.

The depth of a reflector for a given diameter has no noticeable effect on throw. It just changes the proportions of the different parts of the beam. It’s simple math.

You have made these statements multiple times, but your diagrams don’t prove them. They don’t show anything pertaining to luminous intensity (throw) except for the diameter of the reflector.

The focal length of reflectors does not effect throw.

I included the radiation diagram (the 2 lobes), and most of the light is emitted at 45° angle, or at least, so i’m told by various members.
It makes sense, because even though the forward bit is brightest, this is just in 1 direction (forward), whereas at 45° it shines around. That’s why the lobes are 100% or factor 1 at 45°
I do have some doubts about this though, since i found an aspheric with the same diameter should catch less light but throws further none the less (Tested SupwildFire reflector compared to B158 lens)

Yeah, i expected we would disagree again on this… :slight_smile:
But with every collimating optic the focal length matters regarding the size of the projection.
The question is:
do you want to decrease the focal length in exchange for a few more lumens hitting the reflector?
Look how every bit of increased depth adds less and less degrees of collimated light.
Not only that, but the combined intensity of this rim of light weakens accordingly.
Is it worth it?
I doubt it.
Unless the lobed radiation diagram is incorrect, which could be the case…

The radiation diagram with the lobes is correct, and so as you make the reflector deeper and deeper the gains in light collection become less. But the interpretation that the light is “weaker” at these angles is not correct. When it comes to throw it’s the luminance (and frontal area) that matters, and the luminance is the same from all angles.

It’s not weaker, but there’s less of it, otherwise you wouldn’t have those lobes, right?
It’s quite hard to put it into words… :person_facepalming:
But still, experimenting with a B158 lens on a SupWildFire suggest the lobes misrepresent reality…
So i don’t know.
But what strikes me every time this is discussed, is that the focal distances around that “magical” 45° is not taken into account.
In my experience a not so deep reflector makes a better thrower, because it’s a larger parabola size.
But obviously a very very short reflector will simply catch much less light to collimate.
I think the best proportions are between 3:4 and 1:1 (width : depth).

This is kinda going off topic since the thread is about LEDs, but the max intensity of the spot depends on front area.
That means that for a constant diameter, going deeper will increase the front area and therefore lux because the center circle diminishes in size.
A shallower reflector has a large dead center circle.

This has nothing to do with lobes or lumens, all that matters for throw is LED intensity and the front area.
Yes there are diminishing returns as you make a reflector deeper, but it still is an increase in area.
I made this thing years ago for the BLF GT: Parabola creator
Move the ‘h’ slider around and you will see how the front area changes.

Back on topic:
Enderman has found an active area of research into single-crystal phosphors.
These can be used with LEDs and laser diodes as well. Their primary advantage is better thermal conductivity and lower performance degradation when they are hot. “Hot” actually means as low as 60 Celsius. Our high-power LEDs have junction temperature way higher than that and phosphor is hotter still.
Here’s a nice summary of several research papers concentrating on laser use (in German).
There are already manufacturers of such phosphors. For example Crytur.
Disadvantages:

  • cost, according to Endermann the price starts at several hundred USD. How about larger volume?
  • tint high above black body line. Image from Crytur

I wonder how the phosphor crystals compare to the sintered phosphor that Osram uses.

The crystals have basically no drop in output till 300C
This means you can have a pretty intense laser directed at it without damage.
One university tested up to 14W of blue laser and got 4000lm but it was spread over a large 5mm crystal IIRC, not all in a concentrated spot.
The crystal was not heatsinked to anything either.

These are my main resources:

http://jss.ecsdl.org/content/5/10/R172.full