Future development of the maximum luminance of LEDs

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The_Driver
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1.66mm^2 for the first version from 2012-2014

https://www.taschenlampen-forum.de/threads/leuchtdichten.23324/

Agro
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Then koef3 got about 216 cd/mm²

The_Driver
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Agro wrote:
Then koef3 got about 216 cd/mm²

One thing to note here is that the way of measuring the die size is not perfectly accurate. It is usually done by carefully taking a picture and then counting pixels.

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What about this LED (don’t know if this LED is already discussed)?
http://www.nichia.co.jp/en/product/led_product_data.html?type=%27NJ2W270...

The_Driver
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Schoki wrote:
What about this LED (don’t know if this LED is already discussed)? http://www.nichia.co.jp/en/product/led_product_data.html?type=%27NJ2W270...

I noticed it a few months ago, but didn’t see any big benefits. The rectangular shape of the die is definitely a downside.

They do state the luminance!

Die size: 0.93mm^2
Real thermal resistance: typ 4.1cd/mm^2
Luminance at 700mA: avg 110cd/mm^2

**Edit: **
The Black Flat is 20% larger, but only does 66cd/mm^2 at 700mA. So the Nichia might actually be really good if one can live with the die shape! Thanks Schoki!

Edit2:
The weird thing is that it’s a 6V LED! This makes it easier to drive the LED to its max in single cell lights, there are good boost drivers available.

I wonder how far apart the two dies are. This could ruin the beam with smo reflectors.

Agro
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OK, so let’s consider the dies separately, so we can compare with Blackie a bit better.
Half-Nichia:
.465 mm² die. 110 cd / mm² at 1.5 A/mm² and 5 W/mm².
Blackie:
1.122 mm² die. 110 cd / mm² at 1.25 A/mm² and 3.85 W/mm².

Nichia has a bit better thermal resistance, but it doesn’t seem to be enough.
Also, its LES is significantly higher than die size in case of Nichia.
So probably not too good….

The_Driver
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I think we really just need to wait for the new Osrams.

Schoki
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Agro wrote:
OK, so let’s consider the dies separately, so we can compare with Blackie a bit better.
Half-Nichia:
.465 mm² die. 110 cd / mm² at 1.5 A/mm² and 5 W/mm².
Blackie:
1.122 mm² die. 110 cd / mm² at 1.25 A/mm² and 3.85 W/mm².

Nichia has a bit better thermal resistance, but it doesn’t seem to be enough.
Also, its LES is significantly higher than die size in case of Nichia.
So probably not too good….


I need some clarification here: candela is Lumens/Steradian, so the value changes with the amount of dies I place next to each other?
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Yeah, I’m keeping tabs on octopart, hopefully soon they will be available in individual units.

The_Driver
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Schoki wrote:
Agro wrote:
OK, so let’s consider the dies separately, so we can compare with Blackie a bit better.
Half-Nichia:
.465 mm² die. 110 cd / mm² at 1.5 A/mm² and 5 W/mm².
Blackie:
1.122 mm² die. 110 cd / mm² at 1.25 A/mm² and 3.85 W/mm².

Nichia has a bit better thermal resistance, but it doesn’t seem to be enough.
Also, its LES is significantly higher than die size in case of Nichia.
So probably not too good….


I need some clarification here: candela is Lumens/Steradian, so the value changes with the amount of dies I place next to each other?

Luminance is candela per square millimeter of die area. This means it’s independent of the angle from which you are looking at the LED. The luminance determines the throw when the LED is combined with a given reflector or optic. The area of the lit up reflector as seen from the position of the hotspot in some distance mutiplied by the luminance determines the Candela (which leads to throw). This means that two LEDs with two reflectors will double the Candela (which leads to throw). A larger LED with the same luminance as a smaller one will not increase throw with a reflector, only the hotspot gets larger.

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+1 Well done, thanks.

djozz wrote:
Nice summary! I’m not in the position to find or correct mistakes, that is a speciality of you german members Smile But i keep following this thread, and am curious about new additions!
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The_Driver wrote:
A larger LED with the same luminance as a smaller one will not increase throw with a reflector, only the hotspot gets larger.

That means no matter how large the emitting area is, the LED (with a given luminance and reflector) will throw the same distance. Then the only thing that changes is the hotspot size?
But increasing the reflector/lens area “seen when looking into it” gives better candela —> more throw.
Right?

And pushing more power through the LED increases the luminance?

The_Driver
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Schoki wrote:
The_Driver wrote:
A larger LED with the same luminance as a smaller one will not increase throw with a reflector, only the hotspot gets larger.

That means no matter how large the emitting area is, the LED (with a given luminance and reflector) will throw the same distance. Then the only thing that changes is the hotspot size?
But increasing the reflector/lens area “seen when looking into it” gives better candela —> more throw.
Right?

And pushing more power through the LED increases the luminance?

Yes.

Here is the formula:
Luminus_intensity [cd] = luminance [cd/mm^2] * area_of_reflector_or_optic [mm^2] * losses [%]
Losses being the reflectivity of the reflector (or the transmission rate of the optic) and the transmission rate of the lens.

Generelly small LEDs which tolerate very high power densities reach the absolute highest luminance values. The Luminus CFT-90 is an outlier.

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The_Driver wrote:
Schoki wrote:
The_Driver wrote:
A larger LED with the same luminance as a smaller one will not increase throw with a reflector, only the hotspot gets larger.

That means no matter how large the emitting area is, the LED (with a given luminance and reflector) will throw the same distance. Then the only thing that changes is the hotspot size?
But increasing the reflector/lens area “seen when looking into it” gives better candela —> more throw.
Right?

And pushing more power through the LED increases the luminance?

Yes.

Here is the formula:
Luminus_intensity [cd] = luminance [cd/mm^2] * area_of_reflector_or_optic [mm^2] * losses [%]
Losses being the reflectivity of the reflector (or the transmission rate of the optic) and the transmission rate of the lens.

Generelly small LEDs which tolerate very high power densities reach the absolute highest luminance values. The Luminus CFT-90 is an outlier.


wait, so luminus intensity doesn’t depend on reflector shape?, so what if i have a very deep reflector( like 2cm diameter OTF) and 20cm OTF but narrow, both have same area, they will throw the same, right ?

Forgot my pen

The_Driver
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mrheosuper wrote:
The_Driver wrote:
Schoki wrote:
The_Driver wrote:
A larger LED with the same luminance as a smaller one will not increase throw with a reflector, only the hotspot gets larger.

That means no matter how large the emitting area is, the LED (with a given luminance and reflector) will throw the same distance. Then the only thing that changes is the hotspot size?
But increasing the reflector/lens area “seen when looking into it” gives better candela —> more throw.
Right?

And pushing more power through the LED increases the luminance?

Yes.

Here is the formula:
Luminus_intensity [cd] = luminance [cd/mm^2] * area_of_reflector_or_optic [mm^2] * losses [%]
Losses being the reflectivity of the reflector (or the transmission rate of the optic) and the transmission rate of the lens.

Generelly small LEDs which tolerate very high power densities reach the absolute highest luminance values. The Luminus CFT-90 is an outlier.


wait, so luminus intensity doesn’t depend on reflector shape?, so what if i have a very deep reflector( like 2cm diameter OTF) and 20cm OTF but narrow, both have same area, they will throw the same, right ?

No, it doesn’t. That’s a very common misconception.

If you have two reflectors with the same outer diameter but one is deeper, the deeper one will have a slightly smaller led opening. This increases the total reflective area slightly. The larger the reflector, the less important this becomes.

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Deeper reflector = smaller hotspot and more corona.
Shallower reflector = bigger hotspot and less corona.

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Nicolaas wrote:
Deeper reflector = smaller hotspot and more corona.
Shallower reflector = bigger hotspot and less corona.

At constant diameter? Deeper reflector = larger hotspot…..
Same intensity * more lm collected by the reflector = larger spot

Saying same thing in other terms…
All parabolas are the same except for the scale. All parabolic reflectors are (geometrically) the same except for the scale and 2 cut points.
Scale is usually expressed in terms of focal length (FL).
For a given emitter beam angle depends on FL and on nothing else. Larger FL = narrower beam.
For constant diameter, larger FL = smaller depth. So less deep = smaller spot.

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Agro wrote:
Nicolaas wrote:
Deeper reflector = smaller hotspot and more corona. Shallower reflector = bigger hotspot and less corona.
At constant diameter? Deeper reflector = larger hotspot..... Same intensity * more lm collected by the reflector = larger spot Saying same thing in other terms... All parabolas are the same except for the scale. All parabolic reflectors are (geometrically) the same except for the scale and 2 cut points. Scale is usually expressed in terms of focal length (FL). For a given emitter beam angle depends on FL and on nothing else. Larger FL = narrower beam. For constant diameter, larger FL = smaller depth. So less deep = smaller spot.
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.

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

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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

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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.

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The_Driver wrote:

Agro wrote:
Nicolaas wrote:
Deeper reflector = smaller hotspot and more corona. Shallower reflector = bigger hotspot and less corona.
At constant diameter? Deeper reflector = larger hotspot….. Same intensity * more lm collected by the reflector = larger spot Saying same thing in other terms… All parabolas are the same except for the scale. All parabolic reflectors are (geometrically) the same except for the scale and 2 cut points. Scale is usually expressed in terms of focal length (FL). For a given emitter beam angle depends on FL and on nothing else. Larger FL = narrower beam. For constant diameter, larger FL = smaller depth. So less deep = smaller spot.
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.

Thank you for the helpful post.

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

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The_Driver wrote:

Agro wrote:
Nicolaas wrote:
Deeper reflector = smaller hotspot and more corona. Shallower reflector = bigger hotspot and less corona.
At constant diameter? Deeper reflector = larger hotspot….. Same intensity * more lm collected by the reflector = larger spot Saying same thing in other terms… All parabolas are the same except for the scale. All parabolic reflectors are (geometrically) the same except for the scale and 2 cut points. Scale is usually expressed in terms of focal length (FL). For a given emitter beam angle depends on FL and on nothing else. Larger FL = narrower beam. For constant diameter, larger FL = smaller depth. So less deep = smaller spot.
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.


Thanks for this, really gives some food for thought. Smile
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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.

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Here you can see how little more depth adds:

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What are you trying to show us with your pictures?

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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.

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Jerommel wrote:
Basically that a less deep reflector is better for throw, when the diameter is fixed.

Enderman’s calculators claim otherwise.
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Jerommel wrote:
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.

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.

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