I have a convoy L5 modded with a XHP-50, I actually modded this light some time ago. But now I wanted to improve the beam profile, you know getting rid of that ugly dark spot.
So I remembered (at least I thought I did) somewhere where somebody did the same thing by placing the reflector further over the LED.
As the title says the L5 uses a smooth reflector, yeah I know that a smooth reflector isn’t ideal for this multi-die LED’s, so focusing is going to be a challange.
At work I was able to use a lathe to modify the reflector so that is fits better over the LED, but there is still a dark spot.
I think that it is improved but only slightly.
So, is this the right way? Or am I doing this completely wrong?
A fun factor, with the reflector mounted I only have 1 mode (maybe DD?) and without the reflector the normal 3 modes :D.
I think the reflector is shorting something?
Oops, forgot to mention that I already have some tape over the contacts.
I’ve also cut the relfector, where the wires would go, a little bit deeper so it has some clearance, though might not be enough…
I really don’t want to mess with the coating in the reflector before I’ve a reserve one.
So shaving the dome might be a solution?
Shaving the dome wouldn’t stop the short, maybe the contacts are poking through the tape when you tighten the bezel, put another layer of tape on and see if that works
Yeah I didn’t read that right… Working 12 hour shifts starting at 4am messes with you a bit… The shaved Dome won’t eliminate the dark spot but may help due to focusing the hotspot
You might try to sand the dome carefully with fine grit sandpaper to make it opaque, I had this idea a while ago but have not tried it. I expect that the hotspot widens a bit and the dark spot more or less gone.
Morning. Can anyone specify what ‘shaving the dome’ means? Is it simply cutting the dome flat instead of de-doming? Is it shaved into a particular shape? Thanks
EDIT: Got an answer. How to shave the XHP70 dome. https://www.youtube.com/watch?v=HzyNsogaizg&feature=youtu.be
I just tested it for you (and myself), with my test-XHP70 that was still lying around:
before:
After sanding, I ended up using quite rough paper: 180 grit 3M sanding paper (3M paper is the grippiest sandpaper I know, never use a different brand), carefully sanding all sides of the dome, took 10 minutes to get the finish a nice opaque.
Cellotaped the ledboard to a smooth plastic C8 reflector, used an almost drained alkaline 9V block for power
The dreambeam:
How the led looks in the reflector, picture was taken through an audio-cd:
Someone must have tried this before????
Like what happens with dedoming, the opaque dome surface causes a certain amount of light redirected into the die, leading to some light loss, increased surface brightness and tint shift, I don't know how large this effect is, I assume considerably less than with dedoming. (unlike dedoming this does not go together with smaller apparent die size)
Don't know how the dome behaves at high power, I guess it will alright but no guarantees. I may try that sometime.
djozz. Nice. Thanks Just a couple days ago I mentioned to someone that we used to sand Luxeon LEDs to get more diffused beams (throw wasn’t priority 10 years ago) and that there is no reason why it wouldn’t work with XHP LEDs. Thanks for proving that it works!
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That’s a freaking cool idea using a CD to reduce light!
Well done dgozz! I have an HP50 in a XTAR TX20,powered by 2 mxjo 18350 batteries.even at a distance of better than 130feet the dark spot in the middle of the beam is still visible. Question, when sanding the dome, ae you using a sanding block? Also how do you deal with the dust caused by sanding? Any comments/help is appreciated. Thanks
Jim
Correct, a small piece of sandpaper, a couch, and and 10 minutes of Zen. The silicon was slippery at first, but after some light rubbing for a while it starts to come off nicely :-) . The dust was blown off and then brushed with a soft brush.
Just a couple days ago I mentioned to someone that we used to sand Luxeon LEDs to get more diffused beams (throw wasn’t priority 10 years ago) and that there is no reason why it wouldn’t work with XHP LEDs. Thanks for proving that it works! 
