Has anyone read any new LED in research?

[Ryanrpm]

Why would there be a decrease in about 30% of the lumens if the dome were removed? Whether the dome is there or not it still emits the same amount of light, right?

 

[jashhash]

I think the light output becomes less as a result because the silver ring consumes a lot of the light. But if the silver ring were removed then we run into problems of thermal management.

I read an article regarding fully immersed PC's last week. Apparently some guys found that they could put all the components of their computer (except the hard drive) and immerse it in silicon oil and it would still work because the oil is non conductive and at the same time the oil would provide cooling for the components. I'm wondering if the same thing could be done in a flashlight. If you could somehow glue a cree (with the dome removed of course) to the base of a reflector and then fill the space between the reflector and lense with clear silicone oil. That should provide an improvement in heat dissipation and at the same time give a tighter beam. The downside to this is that everything will have to be thoroughly sealed and frozen in place. The flashlight bezel would have to be sealed with epoxy & the hole in the reflector would need the same treatment.

 

[Glenn7]

well i just held the aspheric lens from the DEFT in front of the 8W and WOW! i recon you could burn ants @ 5 meters :naughty:
it might be something that you want to look at saabluster :poke:

 

[saabluster]

Why would there be a decrease in about 30% of the lumens if the dome were removed? Whether the dome is there or not it still emits the same amount of light, right?

There is more than one reason. When you remove the dome of a Cree you expose the gel underneath. The gel is not left with a perfect surface and more often than not has tears that run through it which cause the light to diffuse and reflect in many different directions. One other thing to consider and what is not readily apparent is the lengths the manufacturers go to in index matching. The die has a coating on it thats aids in light extraction. This has its own index of refraction. Then it has phosphor over that. Next you have the optical gel that goes in between the phosphor and the glass dome(on the XR-E). After that you have the glass . And finally they have to take into consideration the index of refraction of air. They do their best to make the transition "gentle" when going from one material to the next by carefully choosing the material (among others)by its index of refraction. If the difference from one material to the next is too great it can cause excessive internal reflection and not allow the light to escape. By removing the dome you are undoing all the hard work of the researchers to maximize the output of the LED package.

I think the light output becomes less as a result because the silver ring consumes a lot of the light. But if the silver ring were removed then we run into problems of thermal management.

The ring while not 100% efficient is a reflector and is designed to boost the output of the LED package so it would be wrong to say that it consumes a lot of light. More like it redirects a lot of light. Also the ring plays absolutely no roll in thermal management.

I'm wondering if the same thing could be done in a flashlight. If you could somehow glue a cree (with the dome removed of course) to the base of a reflector and then fill the space between the reflector and lense with clear silicone oil. That should provide an improvement in heat dissipation and at the same time give a tighter beam. The downside to this is that everything will have to be thoroughly sealed and frozen in place. The flashlight bezel would have to be sealed with epoxy & the hole in the reflector would need the same treatment.

There is probably a way to make something like this work but the materials would have to be chosen very carefully and I doubt that particular oil would work very well. For many reasons.

 

[saabluster]

well i just held the aspheric lens from the DEFT in front of the 8W and WOW! i recon you could burn ants @ 5 meters :naughty:
it might be something that you want to look at saabluster :poke:

Since I know of no other way to get those LEDs than to buy the entire light(since they apparently make the LED themselves) that would make for some some very expensive LEDs. I would like to know more about them though. I am very doubtful that they have managed to beat Cree in surface brightness yet. Take the head off the DEFT and just use your hand to focus the DEFT's lens. It is setup to project the beam at close to infinite but try focusing it where the die is visable a few meters in front of you. I am guessing this is what you did with the 8W and is why it seems so intense.

 

[comozo]

I think the light output becomes less as a result because the silver ring consumes a lot of the light. But if the silver ring were removed then we run into problems of thermal management.

I read an article regarding fully immersed PC's last week. Apparently some guys found that they could put all the components of their computer (except the hard drive) and immerse it in silicon oil and it would still work because the oil is non conductive and at the same time the oil would provide cooling for the components. I'm wondering if the same thing could be done in a flashlight. If you could somehow glue a cree (with the dome removed of course) to the base of a reflector and then fill the space between the reflector and lense with clear silicone oil. That should provide an improvement in heat dissipation and at the same time give a tighter beam. The downside to this is that everything will have to be thoroughly sealed and frozen in place. The flashlight bezel would have to be sealed with epoxy & the hole in the reflector would need the same treatment.

Here's what you could use Fluorinert.
http://products3.3m.com/catalog/us/...oilgas_3_0/command_AbcPageHandler/output_html

Some years ago when Techtv was around the ScreenSaver shows Joshua "Yoshi" DeHerrera constructed a pc with components submerged in this fluid http://en.wikipedia.org/wiki/Yoshi_DeHerrera
Screen Savers Techtv history A great show that I miss http://en.wikipedia.org/wiki/The_Screen_Savers

 

[jashhash]

yes I've been looking into Fluorinert but the problem with that stuff is it cost around $700.00 per gallon. Also I'm not sure of the optical clarity of Fluorinert. I was considering using Deionized water which is not electrically conductive, & because Aluminum wont cause the water to re-ionize it might work.

So I've decided against removing the dome since that will cause more problems than it solves. Actually it may be totally unnecessary to remove the led dome in order to remove that magnification effect. It appears that simply immersing the whole LED in water will reverse the magnification effect caused by the dome. I took a couple of comparison shots to verify my hypothesis. I took out a glass and balanced my camera around the rim of the glass to take these shots. One shot was taken dry, the other was taken with just enough water to cover up the dome. It appears that simply immersing the LED causes the die to shrink significantly reducing it's surface area to less than half of the non submersed.

This picture was taken before

this picture was taken after immersion

This picture compares both side by side

 

[saabluster]

So I've decided against removing the dome since that will cause more problems than it solves. Actually it may be totally unnecessary to remove the led dome in order to remove that magnification effect. It appears that simply immersing the whole LED in water will reverse the magnification effect caused by the dome. I took a couple of comparison shots to verify my hypothesis. I took out a glass and balanced my camera around the rim of the glass to take these shots. One shot was taken dry, the other was taken with just enough water to cover up the dome. It appears that simply immersing the LED causes the die to shrink significantly reducing it's surface area to less than half of the non submersed.

Excellent work! I would like to point out however that it may just be easier to encase it in a clear epoxy so it can still be used in a light. It would achieve the same thing, that is apparent die size reduction. That is unless your goal was to provide the additional cooling by running a liquid over it. In that case you would want to remove the dome and ring so that the liquid could run directly over the surface of the die. Otherwise the cooling provided by the liquid would hardly make any difference in the output of the LED because the glass and gel around the die would not transmit the heat fast enough to matter. Also if you are trying to run the LED real hard the water may boil when in contact with the hot die. It would depend on how hard you were trying to push it though. I really don't have a clue when this would come into play as there are several things to consider. Temp of water. Current to the LED. Temperature rise in the water after it has been running awhile. I'm sure there is more I just don't feel like thinking about it in that much depth at the moment. Anyhow. Great work with submerging the LED. I think that is the first time I have seen that here.

 

[Glenn7]

Since I know of no other way to get those LEDs than to buy the entire light(since they apparently make the LED themselves) that would make for some some very expensive LEDs. I would like to know more about them though. I am very doubtful that they have managed to beat Cree in surface brightness yet. Take the head off the DEFT and just use your hand to focus the DEFT's lens. It is setup to project the beam at close to infinite but try focusing it where the die is visable a few meters in front of you. I am guessing this is what you did with the 8W and is why it seems so intense.

yes i used the DEFT aspheric

the die in the 8W wouldn't be quite twice the size of a osram GD - but it is tiny and real hard to photograph

also the 8W die is mounted on a little round pedestal about 5mm high - the little round thing next to the die is a hole of which the tiny gold wires from the die go through - you can see this in the photos that i took - and may i say took a guts effort and time to take (think i will patent it :rolleyes:) nah! well it took two hands a spare light a magnifier a zoom lens my teeth and almost had to use my butt cheeks to take the shots

the photos are full size so you can play with them ie: zoom up to see the wires - enjoy http://picasaweb.google.com.au/glennkath/Eagle8WLED?authkey=4lonB_iH4qw#

 

[jashhash]

If this immersion theory is true that means one could theoretically double the throwing power of any maglight mod. I just ordered an aspheric lense and a UCL & now I'm going to try to make the farthest throwing LED light on CPF :naughty:.

 

[Glenn7]

wouldn't H2O boil make steam an expand and burst the UCL lens? (you need antifreez/antiboil) :poke:

 

[saabluster]

I'm going to try to make the farthest throwing LED light on CPF :naughty:.

Good luck trying to beat the DEFT.:nana:

 

[Ryanrpm]

Good luck trying to beat the DEFT.:nana:

It would be easier to invent transparent liquid tungsten, right? :poke::D

 

[jashhash]

Nah probably wont be able to beat DEFT But maybe come close. Do you think it would be possible to increase the throw of DEFT just by casting a layer of clear epoxy around the LED dome.

 

[saabluster]

It would be easier to invent transparent liquid tungsten, right? :poke::D

Uhhh:thinking:.... I don't know if I'd go that far. But close.:cool:

 

[saabluster]

Nah probably wont be able to beat DEFT But maybe come close. Do you think it would be possible to increase the throw of DEFT just by casting a layer of clear epoxy around the LED dome.

I think its possible. I am going to do some tests though to find out. I already have something that I will be doing on my "Art Light" version of the DEFT that will increase the throw and output. So with this new method of "potting" the LED it will be something to see for sure. I can't wait to do some tests now.

 

[2xTrinity]

I'm wondering if the same thing could be done in a flashlight. If you could somehow glue a cree (with the dome removed of course) to the base of a reflector and then fill the space between the reflector and lense with clear silicone oil. That should provide an improvement in heat dissipation and at the same time give a tighter beam. The downside to this is that everything will have to be thoroughly sealed and frozen in place. The flashlight bezel would have to be sealed with epoxy & the hole in the reflector would need the same treatment.

An easier approach than trying to fill an aluminum reflector with oil, would be to get a total internal reflecting optic, and bond it to the LED (with dome intact) using an index matching fluid. That fluid should ideally have an index of refraction that is in between (specifically, the geometric mean) the index of refraction of the LED glass dome, and the glass or plastic used to make the optic.

The best thrower you could probably make would be a TIR optic cast into the shape of an ellipsoidal reflector + aspheric lens, all in one piece, simialr to this:

Where the LED in question was actually index-matched to the optic (eg, no air in between the LED dome, and an optic) You'd get the smaller apparent die size, the collimation power of an aspheric lens, and the system would gather light emited into ALL angles -- not just the ones directly forward (as is the case in the current DEFT).

If this index matching were done correctly, the dome would basically "disappear." It is the index-difference between the glass dome and the air around it, which causes the refraction that results in the larger apparent die size. Removing the dome if you plan to flood the device with fluid would be counter-producitve.

Finally, a TIR optic will be more efficeint than the aluminum reflector coatings used in most light as well. However, simply doing this to a TIR optic designed to be used "dry" might not work well -- more than likely, an entirely new TIR optic, explicitly designed to be index-matched to your LED, would need to be used.Also, trying to fill an entire light with oil (rather than just a small vacancy between the dome of an LED and the TIR optic) would be difficult to do without trapping bubbles, or dust particles inside -- which would destroy the optical transmittance of the light.

 

[saabluster]

Removing the dome if you plan to flood the device with fluid would be counter-producitve.

You are right that a properly designed TIR would be best but nobody here has the capability to make one and you cannot buy one with the features you are talking about. Removing the dome is counter-productive if being run at lower current levels which is why I suggested just potting with clear epoxy to reduce apparent die size. However, if you are trying to push the die to within an inch of its life, which is the only reason to use the fluid as was talked about, you most certainly want the dome off so the die can be cooled by the liquid running over it.

 

[Bimmerboy]

You are right that a properly designed TIR would be best but nobody here has the capability to make one and you cannot buy one with the features you are talking about.

Actually, one guy here machined his own high quality glass optic which was quite a slick little piece of DIY engineering. I don't remember who it was, but he may have worked in some optical field (ha... get it?... optical field. A little opthamological humor there) for a living, and/or had access to the proper equipment.

If the thread can be dug up, it's possible there's a way to contact him. If there's enough money in it, there's usually always someone willing to do a run of whatever custom item.

 

[DM51]

Actually, one guy here machined his own high quality glass optic which was quite a slick little piece of DIY engineering. I don't remember who it was...

If the thread can be dug up, it's possible there's a way to contact him...

Maybe you mean this thread by Ra?