Those pesky "ghosts" or donuts that are prevelent in multi die emitters such as RGBW and, as far as I've heard XHP. It seems that as soon as you shove four emitters next to each other you get that ghost shadow in the center of the hot spot. Some are worse than others, but any ghost at all can be annoying.
Are there any ghost busters out there?
What I want to know is, if a certain multi die emitter produces a "ghost" area in its profile, what would happen if you installed three of them in a triple reflector? Would the amount of light produced wash away the "ghosts", or, would the "ghost" only be magnified thrice?
I think for a triple, it would be a function of how well the beams were converged. The better the convergence, the worse the donut hole will be. Using OP reflectors and/or diffused lenses can help. O-L recently made seven triple XHP Mag-Lites and he both sanded the domes of the emitters AND stippled the reflectors to get rid of the donut holes.
I have one of those OL Maglites. Its awesome. In truth mine does still have a very slight dim spot right in the center. To see it at all the light has to be on one of the lower levels and pointed at a white wall. On turbo it all washes out even on a white wall and I literally cannot see it when I point the light at any other surface besides a white wall. Honestly I think if I didn’t go looking for it I would have never noticed. Its not much at all and I’m not complaining.
Its tricky though. I’ve built lights with XHP emitters myself and tried the sanded dome trick like he used here. Mine burned up the first time I turned it on — literally cooked its own dome. I have no idea what sort of technique he used here to prevent that but my OL Maglite shows no signs of doing it. I guess that’s the difference between knowing what you’re doing and not.
Wait, a 219A isn’t a multi-chip die. Are you saying you put two of them inside a single reflector? That would certainly give you a strange looking beam. I don’t know about a donut, maybe more like a hot-dog?
I’ve done some dual nichia 219A mods since they were cheap, hopefully better CRI than the CW cree (/LB?) leds they replaced, and i liked the option of using WW flashlights… (i’ve modded a sk68 with a ww nichia 119, a bikelight/headlamp with dual 219A + matte tape, 2x sk98 with dual 219A, and put some single 219A in some other flashlights…)
i’ll try to post some pictures of my trustfire 3t6, taken with the camera in my phone on auto
some matte tape to diffuse the beam
results in a smooth beam profile
without the front glass, here you see my 3x dual nichias
and here is the donut in the beam
compared to my other stock 3t6 with CW xm-l
and here is a pic of just my 3t6
So the 3t6 indoors have a donut in the beam profile, haven’t tested it outside without matte tape actually.
Maybe one way to get rid of the ghost is to use a strong single die emitter to fill in the hole from the multi dies. Maybe lumen robbing OP reflectors and such can be avoided that way.
The Convoy L6 (XHP-70) was said to be devoid of the “nasty cross of death” by an initial short review. Id wait for others to chime in to re-conform.
J-Dub74 wrote:
I can tell you that the hole in the center of the beam that plagues so many XHP70 lights (including the S70) is not present in the L6. Smile
The L6 shows no dark cross or hole in the center of the beam indoors or out. Convoy did an excellent job tuning that out. The only situation that allows me to see the cross in the beam center is indoors pointing at a wall in the lowest mode at a distance of less than 2 feet from the wall. Any distance beyond that you’re looking at a clean round hot spot.
Well, it’s my understanding that a triple won’t help at all with washing out the donut effect. Go look at O-L’s recent seven Mags thread. Those are triple XHP’s and he tried without any tricks and got the donut effect. Only after both stippling the reflectors AND sanding the domes did he get any relief from it. It simply doesn’t wash out. You have to scrub it out instead!
Well, I guess that’s what you have to put up with if you want all the throw from these emitters. The ghost is merely an annoyance, but doesn’t really hurt anything except you can see it. Sanding emitters and going with OP or stifled reflectors just defeats the whole point of that particular emitter in the first place. I guess I’ll have to try it and find out.
