30 Amp LED Sabers & Fluorescence Enhanced Saber Blades (Part 1 - Saber)

[Sunrider]

 The burnt trash bag says it all.  8)...  Nothing else has been that bright yet.  On my SSR 90s it is pretty warm with a hand in front of the emitter but nothing like that. Thanks for sharing this valuable research and doing all that work.  The high binned green must be at least  twice as bright as anything I have done.  Bravo

These leds should be able light up a blade well enough to appear just like in the films anywhere but direct sunlight which is as about as bright as it gets without getting into the "bad for your eyes" zone.  Everyone should be careful not to get light this powerful directly in their eyes.

[Wilson McDermot]

As a high-power lightsaber enthusiast myself, (Supernova/Starburst 27-watt blade) I have to applaud your creativity and the amount of excellent work you've done. More importantly, you've created an entirely new form of lightsaber architecture. I congratulate you.

My one question concerns the total power to the LED. You mention many times that you're driving it at 30 amps but I don't recall the voltage. If it's on the order of 4 volts and you're working the LED at a 50-percent duty cycle, I calculate that the average power to the LED is 30 amps x 4 volts x 0.50 = 60 watts. Is this correct?

Thank you.   

[Photonic Bladesmith]

As a high-power lightsaber enthusiast myself, (Supernova/Starburst 27-watt blade) I have to applaud your creativity and the amount of excellent work you've done. More importantly, you've created an entirely new form of lightsaber architecture. I congratulate you.

My one question concerns the total power to the LED. You mention many times that you're driving it at 30 amps but I don't recall the voltage. If it's on the order of 4 volts and you're working the LED at a 50-percent duty cycle, I calculate that the average power to the LED is 30 amps x 4 volts x 0.50 = 60 watts. Is this correct?

Thank you.

The voltage drop at 30 Amps is about 4.5 volts.   

The measured radiometric light output at 30 amps is 15 watts if you want to calculate the net heat production at the LED. 

Since the LED is powered by a pair of 18650 lithium cells run through a linear regulator there is an additional regulator heat load that makes the saber hilt too hot to hold onto without gloves after a few minutes of continuous operation.

[Wilson McDermot]

Thanks for the reply, though I'm still a little confused. If the input power to the LED is 30 amps at 4.5 volts, that comes out to 135 watts. At a 50-percent duty cycle that suggests the actual power is half or 67.5 watts. Yet you stated that the radiometric (light) output is 15 watts. That implies that the LED is only operating at 15/67.5 = 22-percent efficiency. I thought LEDs were up around 80-percent. Or does that 15-watt value include the violet-green conversion loss through the blade wall's luminous layer?

You have both my sympathies and respect dealing with that 30 amp draw. At its maximum Supernova only drew 8 amps and even at that low current, compared to your beast, Ohmic losses were a real problem.

[Photonic Bladesmith]

Thanks for the reply, though I'm still a little confused. If the input power to the LED is 30 amps at 4.5 volts, that comes out to 135 watts. At a 50-percent duty cycle that suggests the actual power is half or 67.5 watts. Yet you stated that the radiometric (light) output is 15 watts. That implies that the LED is only operating at 15/67.5 = 22-percent efficiency. I thought LEDs were up around 80-percent. Or does that 15-watt value include the violet-green conversion loss through the blade wall's luminous layer?

You have both my sympathies and respect dealing with that 30 amp draw. At its maximum Supernova only drew 8 amps and even at that low current, compared to your beast, Ohmic losses were a real problem.

My measured efficiency for the 30 amp blue LED lightsaber is actually only 11% (  15 watts / (30 amps x 4.5 volts)  )
The Luminous devices CBT120 LED I used in the 30 amp saber is old technology compared to the blue CREE XP-E2 LED which I measured as having a maximum efficiency of 35% at its officially rated maximum current of 1 amp per LED element.
However, the absolute maximum power output of a maximally overdriven quad blue CREE XP-E2 is only 5 watts (at 6 amps), though with an efficiency of 26% at this overdrive current.



The optical output power to electrical input power efficiency of commercially available high power visible spectrum LEDs are currently in the 15% to 40% range.
The table is for 2012 data, but the efficiency values are still roughly equal to that of the current state of the art CREE and Rebel LEDs used in our sabers.



The high laboratory efficiency mentioned for experimental LEDs are often for low power devices operated under unrealistic conditions.

As an extreme example: one group created an LED that was 230% efficient when operated in the picowatt regime.  They used the trick of exciting the dopants to metastable quantum levels that could be boosted to higher energy photon emitting states  by absorbing thermally generated crystal lattice phonons (quantum of vibrational energy).

LED's efficiency exceeds 100%

 

[Wilson McDermot]

Thank you! That was a great answer. I appreciate your taking the time.

[Onli-Won Kanomi]

"...exceeds 100%"

At first I almost did a spit-take while my 'inner-Sheldon' Wilhelm-screamed *in LS voice* "Nooooooo that's not true, that's impossible; Thermodynamics 2! " but then I actually read the article and was "um, background eh not really over unity, OK then"... LOL

*single raised eyebrow*

Fascinating!

[Maxpintx]

Like I have long seen this issue. This is a good example. With this interesting debate again.