Why do Green LEDs throw farther than White LEDs?

Oh boy and the datasheets above say that. :open_mouth:

So there’s one way to make a white LED more efficient, make it greener.
And I think that is what’s happening for a couple of years now.

Yes that is one of the ways, of course in the last years it’s mostly lower forwards voltage at the same current which made them more efficient, they were greenish since ever anyway, it’s not a recent years thing to make it greener.

Yes, for example for 1W of radiant flux :

Royal blue blue (450nm) : 28.5lm
Green (520nm) : 441lm
red (620nm) : 216lm
deep red (660nm) : 22.6lm

The osram F1 is phosphor converted green so the blue LED with green phosphors on top, but while there is some radiant flux loss due to the phosphor conversion, luminous flux ends up higher.

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When you give two people the same flashlights, they will record different Cd on their own meters.
Even when lights AND meters change hands, they will record different values.
So I will limit myself to revealing a percentage.

If it is just the change in color I don’t know, but I own a few C8’s equipped wit XP-E reflector.
After swapping a white 1mm² with a green 1mm², the candela on my meter exceeded that of my TN32.
If I use that percentage, and believe the claims of Thrunite that a TN32 does 250,000Cd,
my green C8 scored a quite decent 340,000+ Cd.
It even topped the results of the “old” white 1mm² and the 50+mm reflector of my “Fandyvoy” lego mod.

As layman I would say, the green has a better efficiency, AND can manage more amps in direct drive.

It’s the opposite of unheard of, it’s exactly what is expected. With all other things being equal increasing brightness increases throw otherwise all brightness modes on a single light would have the same throw.

This thread may help you understand more about throw: Flashlight Optics - Dome, Dedoming and Throw

white gives 15% less throw than green, but shows more accurate colors… :slight_smile:

fable:

She said: Honey, I see a big animal, way down yonder

He said: is it a Black Bear or a Brown bear?

She said: neither… it looks more like a Green animal, I cant tell if its a Bear….

He said: well, dont worry, animals cant see Green light, so they wont bother us

She said: oh, then, can we store food inside the tent?

:confounded:

now a true story
went camping with a friend and his wife
They were sleepig in a VW Van.

Wife made sure not to store food in the vehicle, due to bear warnings, but, instead of storing the food in the Bear Proof Locker provided at the campsite, she put it in the tent they use to store their gear, outside the vehicle.

Next morning… tent is shredded, food is gone
and apparently bears like toothpaste too :slight_smile:

no damage to the VW Van, nor its occupants.

Nobody saw what color the bear was… :person_facepalming:

The green led in these lights is a phosfor converted green, it uses the same blue led as a pump as white leds. In my test of this led I tried to explain why it throws better.

That's a funny story jon_slider..

Thanks Djozz.. so green has/needs a higher Voltage but will also produce more lumens at the same current.

So they will have a different runtime graph as well, with green dropping off quicker because of the higher Voltage it needs.

Green requiring more voltage than Red and less than Blue only applies to green emitting semis, not to green phosphor coated blues :wink:

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I’ve thought for a while that someone should take these PC color and white emitters, test them as is, then retest them all after carefully scraping off all the phosphor.

My hypothesis is that the green phosphor not only is more visually “efficient” that is radiant wattage vs lumens but also in conversion efficiency (watts to watts). I believe, based on the green nm1 test Djozz performed, that the peak current limiter in this emitter is the phosphor overheating. I will go as far as also presuming that the difference in Vf is also largely due to this. Less efficient phosphor = more heat = lower Vf. This can also be seen in some nichia and Samsung emitter tests posted around here IIRC when Ra70 vs Ra90 variations are compared

The human eye is like 2x as sensitive to green light as to balanced white light, so the phosphor could be less efficient and still get more lumens.

rated throw is calculated from actual lux rating measured, how our eyes see color has no bearing on the instrument, green just makes more lumens due to chemical composition of the chip,

Not true. The ‘lumen’ is 100% based on the human eyes sensitivity curve.

First paragraph of the Wikipedia page.

Why not to ask manufacturer?

Because you usually won't be able to reach the person who knows this stuff :) You will probably get in touch with somebody from support who know how to turn on a flashlight, and probably not more than that

the article has really nothing to do with the topic, since we are talking about lux measured by instruments, the fact that our eyes see colors differently and more sensitive to green than red, which is true, but it has no effect on measured lumens nor lux

The whole purpose of the units lumen and lux is to recreate the human eye’s perception.

So a measuring device for lux should do exactly that.

uh no, the purpose of the devices is to measure actual lumens and lux, not perceived ones. same as tape measure is there to measure actual distance, not how it looks to us. that is why we use instruments, for objective data, how we perceive it, is irrelevant as far as actual results measured.

What you don’t want to understand is that there are no “actual” lumens and lux other than the units that were created according to the human eye’s sensivity.

Again, there is no such thing as actual and perceived lumens.