Although Iíve successfully swapped several XHP-50 emitters, despite my best efforts at zeroing in the focus I simple could not eliminate the multi-die artifact/shadow from appearing in the hotspot of my most recent host a Surefire KL6
From what I could gather two popular solutions to eliminating artifacts involve deploying an OP reflector (already in the KL6) and de-doming and/or sanding the surface of the dome itself. (De-focusing the hotspot can also reduce the artifact but that sort of defeats the purpose.)
De-doming has the effect of reducing overall light out the front and/or possibly introducing unwanted green tint in the corona; in exchange for greater emitter intensity and a bright hotspot. Since my light had a relatively deep reflector and the emitter was already well focused I didnít feel this need.
Sanding the dome seemed like a good option but not without its risks. Sanding might also reduce overall output and possibly diffuse the tight hot-spot. Both are bearable trade-offs but an alarming risk that some sanders reported was destruction of their emitters (usually because the emitters were being pushed to/beyond their power limits) because of residue from sanding (or possibly excessive internal reflections?)
After some fooling around to verify that the artifact/shadow results from the lines between the multi-dies themselves and not some other complex interaction of emitter and reflector, I decided to see if just focusing on the die lines (pun) alone would work. I decided to sand just along/above the separation lines/images themselves.
Hereís a photo of the final criss-cross sanded XHP-50 -
I cut/used a ~1 mm (<1/32 in) wide strip of dry/wet emery about ~80mm (~3 in.) long. Wet/dry emery is more flexible and follows the contours of the dome better than dry coarse sandpaper. I used 1000-grit which is fine enough to just cloud the surface of the dome. It also slides easier than coarser grades of paper. Sort of like flossing my emitter .
The resulting beam still has a slight artifact barely noticeable perhaps when white wall hunting but otherwise it's gone. I do not have any before/after beam comparison shots but from what Iíve read although visible in person, the artifacts donít show in photos anyway.
YMMV but this should work for just about any multi-die emitter. Not sure if it'd be effective enough on a SMO reflector. If you try this and it works for you (or even if it doesnít ) please share your findings. AND, if someone who tries this can take actual before and after measurements to quantify any changes in brightness from using this option to eliminate multi-die emitter artifact that would be really useful.