# XLED Technology — Brighter than Daylight?



## Polargirl (Apr 10, 2014)

Someone from The Netherlands is apparently claiming to make brighter than direct sunlight flashlights. I haven't seen any threads on this flashlight so I thought I'd start my own discussion. The table below measured in lux gives a relative example of the sun's lighting power.


Examples*Illuminance**Surfaces illuminated by:*0.0001 luxMoonless, overcast night sky (starlight)[3]​0.002 luxMoonless clear night sky with airglow[3]​0.27–1.0 luxFull moon on a clear night[3]​[4]​3.4 luxDark limit of civil twilight under a clear sky[5]​50 luxFamily living room lights (Australia, 1998)[6]​80 luxOffice building hallway/toilet lighting[7]​[8]​100 luxVery dark overcast day[3]​320–500 luxOffice lighting[9]​[10]​[11]​400 luxSunrise or sunset on a clear day.1000 luxOvercast day;[3]​ typical TV studio lighting10000–25000 luxFull daylight (not direct sun)[3]​32000–100000 luxDirect sunlight
http://en.wikipedia.org/wiki/Lux


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## AnAppleSnail (Apr 10, 2014)

"Higher lux than the sun when shining on something very near" is very different from "Brighter than the sun."

Sunlight covers the whole world to at least 50 klux, and I can see things about 2km away that aren't mountains or buildings. That's (2000m x 2000m x 50000 lux = 200000000000) or (2x10^12) lumens. So the sun lighting a tiny fraction of the world is at least 10000000 (Ten million) XLED lamps.

Let's take their statement that the big XLED lamp emits 20000 lumen. To reach 50 klux (Spring sunlight where I live), it would have to only light 0.4 m square, or something about the size of a steering wheel.


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## Polargirl (Apr 10, 2014)

AnAppleSnail said:


> "Higher lux than the sun when shining on something very near" is very different from "Brighter than the sun."
> 
> Sunlight covers the whole world to at least 50 klux, and I can see things about 2km away that aren't mountains or buildings. That's (2000m x 2000m x 50000 lux = 200000000000) or (2x10^12) lumens. So the sun lighting a tiny fraction of the world is at least 10000000 (Ten million) XLED lamps.
> 
> Let's take their statement that the big XLED lamp emits 20000 lumen. To reach 50 klux (Spring sunlight where I live), it would have to only light 0.4 m square, or something about the size of a steering wheel.



I was just thinking a simple square meter. I didn't think about multiplying it how many square meters the Earth is.

I suppose if you'd like to be technical, you'd have to measure the sun's light output throughout the solar system and maybe slightly beyond. You forgot to measure the rest of the solar system the way I forgot to think about more than one square meter. Brain farts happens.

Here is an interesting light engineering challenge. What kind of light would have to be built in order for the Continental USA to be constantly illuminated at the same level as the summer solstice at 13:00 CDT if the light was orbiting the Earth at the same altitude as The International Space Station? If that orbit is too low with today's flashlight technology, feel free to go all the way up to geosynchronous orbit but please provide specs. Maybe this question should be a thread of its own.


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## AnAppleSnail (Apr 14, 2014)

Polargirl said:


> Here is an interesting light engineering challenge. What kind of light would have to be built in order for the Continental USA to be constantly illuminated at the same level as the summer solstice at 13:00 CDT if the light was orbiting the Earth at the same altitude as The International Space Station? If that orbit is too low with today's flashlight technology, feel free to go all the way up to geosynchronous orbit but please provide specs. Maybe this question should be a thread of its own.



The worst case scenario is night. The moon phase isn't close to mattering for this calculation. 

The continental US is right about 8 million square kilometers. Let's use 80klux for 'noonday summer sun' at our latitude, so we need 80,000 lux for each square meter... All 8000000000000 (8*10^12 square meters) of them.

This requires 6.4*10^17 lumens, needing 6.4*10^9 megawatts, assuming 100 lumen per watt. I leave it as an exercise to the reader to determine the necessary optics and a comparison for how much power this consumes.


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## TEEJ (Apr 15, 2014)

They use Ryobi for the battery packs and mounts, which is interesting.

The whole "sun thing" is not really relevant, as you can't compare lux at a few million miles to lux at one meter, etc. IE: To be truly as bright as the sun, in lux, it would need to have the same cd (Forget the lumens for now, that's even worse off).



A few miles away, the XLED would not produce the same lux on a target as the sun would in broad daylight, let alone from a few million miles away.

So, if the sun can produce ~ 30 k lux at a range of ~ 90 million miles, that's a cd of ~ 6.75e+26000 or so?

That's a LOT more than the XLED cd. Its not really that close at all. I didn't even check the math, I could be off by a few orders of magnitude and it won't really flip the relationship, its just that far off.


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## ven (Apr 15, 2014)

From their pictures to me clearly shows its nothing compared to sunlight..................

If i had a choice of looking into the XLED for 10 seconds,or the sun .............i know what i would pick and what my eyes survive!

Maybe a perfect light for RemcoM


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