X-ML de-doming method with 100% success?

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Ledsmoke
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In my continued attempts to get a good polished surface I think I am now polishing the phosphor layer. The lux dropped to 97 kCd after last attempt. I still think a much better result will be gotten if you leave a well polished totally clear surface and a little more than 1 mm dome aboce the phosphor.

Still learning here so bear with me.

~ Ledsmoke ~

Dutch humor:

[quote=djozz]

 I do not think that the BLF-community ben

Ledsmoke
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I was wrong! 

I tried the trick Xandre has told us about that Andi does. Running the flashlight till it is freaking hot and then peel off the dome with my fingernail. It turns out there WAS a thin layer of dome left. I got it all off except a little around the bonding wires.

Now up to a steady 125 kCd.

 

I LOVE THE BLF! WOOT!

~ Ledsmoke ~

Dutch humor:

[quote=djozz]

 I do not think that the BLF-community ben

Ledsmoke
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Update: Reflector position critical! Just fiddled with it and although warm now (on for 5+ mins) i get a steady 145 kCd! Woot!

~ Ledsmoke ~

Dutch humor:

[quote=djozz]

 I do not think that the BLF-community ben

Andi
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Gratulations!

But @moment i think, a cookplate is better, because on some flashlights the heat is not enough.
Then heat dome, not the star.

Next i will try Chemicals. >)


Ledsmoke
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You are a madman Andi. I love your work!

BTW:

Have you tried XML T6 on copper star from DX.COM? I have very very good experience with them. And good color/tint too even with dome! I wish they would bring the U3 bin on the copper star. Solid copper rocks!

~ Ledsmoke ~

Dutch humor:

[quote=djozz]

 I do not think that the BLF-community ben

Ledsmoke
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And my beam is not fully "together" (sorry I forget english words when excited) at 5 meters. At 7,8 meters I measure 2690 lux meaning I have ~ 163 kCd @ 1m! YES!

~ Ledsmoke ~

Dutch humor:

[quote=djozz]

 I do not think that the BLF-community ben

LowLumen
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Ok, you guys convinced me to go ahead & peel the rest of the dome off my T6 3C XM-L (in the craptastic SMO P60) I put the solder iron tip next to the LED, and used magnifier, tweezers, & X-acto knife to carefully peel it off. It never got hot enough to melt the solder. There is still some spooge around the bonding wires I’m not messing with, but the chip is entirely clear.
I was finally able to focus a decent hot spot with this reflector, though still ringy.
I am quite sure I left all the phosphor intact as this thing is really warm now. It looks to be 3500-4000K now, I don’t know, it’s the warmest LED I have. If I do another, I’ll start with a U2 1A or such, and hope to end up at 5000K. This color shift is fascinating; somehow the average light must be traveling through more of the phosphor(?) And this warm shift continued when removing the last .35mm of the dome too.

DarkSide
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I heat the board directly and its firmly attached to a heat sink. I heat the board quickly with high
heat enough to melt the adhesive holding the dom and i use tweezers to pull it off. Now your using heat as well, only to a different location and completely different approach. I cant say i would suggest this but perhaps if you try this method before putting your iron to the dome itself.
I haven’t killed or scratched one LED yet ( by this method) but i have killed plenty of diodes..

rdrfronty wrote:
Well I killed my Z8 last night trying the heat up method. It looks like it broke the wires. I agree that method does work – the dome did get removed. But either I didn’t get the temperature right or I just wasn’t careful enough. It came off in a couple pieces. But it’s dead for sure. Oh we’ll I guess it gives me an excuse to learn how to change out led stars. Guess I can upgrade it to a U2 this time. Anybody have a link for a US distributer of LED’s?

 


Ledsmoke
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I fiddled on with that reflector positioning and now I get a steady 168 kCd after 30 sec and initially when turned on it gives about 183 kCd.

Now I wait for xml 2 led with even more impatience! Muahahaha!

 

EDIT: Corrected some strange spelling....

~ Ledsmoke ~

Dutch humor:

[quote=djozz]

 I do not think that the BLF-community ben

Manual Man
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I think the XML-2 is very close: I read today in an electronics magazine that Cree stated the are expecting to release a 200 lm per watt LED before the end of 2012… call me skeptical (XP-G2 is something like 160 lm / W), but ever if they manage 180 lm / Watt it is a decent step up. I think the XML-2 would be this LED. Big Smile

viffer750
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dedomed sky ray A0 clone 85klux initial J)
Not bad from a little light.

I think the dedome method was from Andi: I heated up the led and the pill at 4A for a few minutes, and the dome came down very easily.

unique engrish language... Smile

 

CheapThrills
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Manual Man wrote:
I think the XML-2 is very close: I read today in an electronics magazine that Cree stated the are expecting to release a 200 lm per watt LED before the end of 2012… call me skeptical (XP-G2 is something like 160 lm / W), but ever if they manage 180 lm / Watt it is a decent step up. I think the XML-2 would be this LED. Big Smile

200lm/W is probably assumed to be achieved at pretty low drive current and ?CRI of color renderition Smile

JohnnyMac
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viffer750 wrote:
dedomed "sky ray A0":http://budgetlightforum.com/node/9728 clone 85klux initial J) Not bad from a little light. I think the dedome method was from Andi: I heated up the led and the pill at 4A for a few minutes, and the dome came down very easily. !{height:480px; width:640px}https://lh4.googleusercontent.com/-frackoduyCI/UGyc_QhuhzI/AAAAAAAAAzs/B...! I actually would have expected more out of that little bastage. Considering how well it throws normally I would have guessed at least 120k+ considering the numbers other lights are pulling. I'm betting the wide base reflector reduces lux when you dedome.
agenthex
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mattthemuppet wrote:
so, despite Agenthex’ rather obnoxious approach to discussion (try that at a conference and see how much people want to share knowledge with you..), it did prompt me to fix some glaring holes in my knowledge about how LEDs work which can only be a good thing.

Here’s one of the better references I found
http://www.digikey.com/us/en/techzone/lighting/resources/articles/Improv...LED-Light-Emission.html
although there are several others (many use excerpts from the wikipedia entry), which does a good job explaining things.

So, as I understand it, the dome exists to more efficiently extract light from the phosphor by reducing the difference in refractive index between the phosphor (3.7ish) and the air (1, I think) and by allowing the light leaving the dome to exit at as perpendicular an angle as possible. I could not find any references to the dome focusing the light in any way (if it did, why would we need optics?), only that it prevented light internally reflecting inside the phosphor. There are some prospective technologies to harness the remaining internal reflection, but right now it just ends up as heat. I would expect the decrease in total light output on de-doming to be the result of less efficient light extraction (or more internal reflection).

Why de-doming would effect the size of the hotspot, I have no idea. Perhaps because the light leaving the remainder of the dome is not doing so perpendicular to the dome and is therefore refracted away from the normal when it goes from dome to air, thus more light hits the reflector and is focused into the hotspot? It seems intuitive that the light isn’t leaving the LED in a way which the optic designer accounted for in the design. Perhaps it has the effect of moving the effective focal point of the reflector backwards, behind the emitter?

Either, my thanks to Agenthex for his inspiration for my education. I think I’ll leave the lesson on how to correct peoples’ misconceptions on the lab floor though, I can’t see any of my students benefiting from it Smile

If this is even remotely true, it should be easy enough to test. Without the dome of maybe RI ~1.5, the output should drop in half, which is hard to believe given the results here.

Also the RI = 3.7 is of the semi material itself (transparent to the emitted wavelengths), not phosphor layer.

The focus of the dome is evident enough from its shape and >1 RI, and comparison between CREE app note and COS curve as already noted.

Reading this makes you smarter: http://lesswrong.com/

Manual Man
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Well, de-domed a XML headlamp ( ~38mm reflector), while it still goes I removed a fair bit of phosphor from two of the corners.. the pictures can explain better then I can:

Before:

After:

Left to right: P60 XPG at 1A, OP reflector, XML at ~800mA in 38mm SMO reflector and Trustfire X9 at ~ 2.4A ( batteries needs recharging)

Smaller hotspot and marginally more intense, still good for all flood as the colour is even (if slightly blue) without the reflector.

I pressed the LED dome lightly against a hotplate for about 10 seconds before pushing it upwards with a knife blade…. I don’t think I let it get hot enough or perhaps I should have heated it from the underside? Going to replace the LED anyway now.

DarkSide
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Anyone have specs for the XM-L U3?

 


viffer750
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JohnnyMac wrote:
Wow! I actually would have expected more out of that little bastage. Considering how well it throws normally I would have guessed at least 120k+ considering the numbers other lights are pulling. I’m betting the wide base reflector reduces lux when you dedome.

Don’t want too much from this little light. Other lights have a (much) larger reflector in this topic where has been measured 120-180-200kcd. So, it’s not fair to compare with them. With an original xm-l it can 45kcd maximum, and this increased to 85kcd, it’s not so bad.
Not so bad??? It’s an outstanding value from such a little light. Smile

unique engrish language... Smile

 

Pulsar13
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85kcd is really really good result for a single battery light. Not to mention the $15 pricetag (without emitter swap yet of course). 

Anyone doing this on Small Sun T13? Nice big reflector there, standard T6 XM-L ready to peel, and with the resistor mod it should really give good result.

I plan to do T13, but mine has not arrived yet. And even if it did, I don't have a way to measure lux anyway to publish result. 

EDIT: Sorry, price was $22 shipped.

Slewflash
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Pulsar13 wrote:

85kcd is really really good result for a single battery light. Not to mention the $15 pricetag (without emitter swap yet of course). 

Anyone doing this on Small Sun T13? Nice big reflector there, standard T6 XM-L ready to peel, and with the resistor mod it should really give good result.

I plan to do T13, but mine has not arrived yet. And even if it did, I don’t have a way to measure lux anyway to publish result. 

Except at 1 meter the hotspot is around 5cm… It’s absolutely tiny. I did it to mine before accidentally breaking the bond wires trying to fix it.

Slewflash 

Tecmo
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My X9 is killing my STL-V2 now. I keep grabbing it when I head outside. Hard not to try de-doming the V2, but I like the beam….

viffer750
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outdoor beamshots Skyray A0 clone, distance 200m

mouse out with dome 

mouse over dedome

 

1

unique engrish language... Smile

 

Tecmo
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Nice mouseover… that pretty much nails the results I had as well.

Tecmo
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X9 de-domed
Old lux 38,120kcd
New lux 61,920kcd

Old lumens 786
New lumens 575

LowLumen
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Nice beamshot viffer750. Amazing the warm (er yellow) shift on these de-domed. Mine too. I est from 3C 5000K to 3500K (er yellow). IF I do another, I’ll start with a U2 1A and hope to end up at 5000K. Craig at Illumination Supply has some U2 1A on 16mm boards on sale for $6.50……

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viffer750 wrote:

outdoor beamshots Skyray A0 clone, distance 200m

mouse out with dome 

mouse over dedome

 

 

You're absolutely right, Viffer. That little A0 clone is so small I forget that the reflector isn't as big as it's output makes you think it is. That is an amazing difference!

Manual Man
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The C8s arrived!!! (5 of them :bigsmile: )

They cost me >$15US each and include aluminum reflectors, glass lenses and an overall very good fit and finish considering the price.

Three of the five have quite cold tints so I decided one of those needed de-doming. I used the Dremel method this time: ground the LED dome down to <1mm and stuck the felt wheel in before finishing with a optics cloth.

So far it looks very promising: When at 2.5A (battery at 3.8V) it throws as well as a X9 at 2A (3.6V) however the hotspot is 1/2 the size…. just recharging the batteries to put them both on a even footing… photos to follow. Big Smile

CheapThrills
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viffer750 wrote:

outdoor beamshots Skyray A0 clone, distance 200m

mouse out with dome 

mouse over dedome

 

1

Looks like the tint definitely got better.
Are colors like that in reality also? Smile

Manual Man
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Beam-shots of the cut-domed C8 vs X9


Stock vs Cut and polished dome… the difference is more then is shown by the camera


X9 vs cut + polished XML of the C8

viffer750
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CheapThrills wrote:
Are colors like that in reality also? Smile

yes, similar

unique engrish language... Smile

 

Manual Man
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Had to a have another play around with the C8s…. and here is what i got:


The partial de-domed I mentioned in the post a few above is on the left and a complete de-dome on the right, both were the same tint before any mods.

To do this I used the method of running the LED until it got very hot (took pill out of C8 body and attached it to a battery, took all of 1 min to get hot enough) and then I just peeled it off… piece of cake and left a perfect finish.

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