NEXTORCH        
Results 1 to 8 of 8

Thread: Flossing to Eliminate XHP-emitter Multi-die Artifacts

  1. #1
    Flashaholic
    Join Date
    Feb 2004
    Location
    Garden State, USA
    Posts
    207

    Lightbulb Flossing to Eliminate XHP-emitter Multi-die Artifacts

    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.
    Last edited by pc_light; 02-28-2017 at 11:01 PM. Reason: Corrected some measurements.
    "may you live light and phosphor" - Mr. Spark

  2. #2
    Flashaholic* degarb's Avatar
    Join Date
    Oct 2007
    Location
    Akron, Ohio
    Posts
    1,860

    Default Re: Flossing to Eliminate XHP-emitter Multi-die Artifacts

    Ingenious.

    Since the Hotspot is the side emissions, reflected into center, I would suspect it mostly would only partly help the hot spot.

    I am not a fan lamp shades. So, the partial sand appeals to me. Probably, should do a ceiling bounce test before and after to see if any drop.
    Some people are all lumens and no lux, while others are all lux and no lumens. Some just thank God they have neither.-- All of my lights have throw--some pretty darn far, into the garbage.

  3. #3
    Flashaholic
    Join Date
    Feb 2004
    Location
    Garden State, USA
    Posts
    207

    Default Re: Flossing to Eliminate XHP-emitter Multi-die Artifacts

    Thanks degarb, yeah I thought it was worth sharing.

    At the time I was so hung-up on getting rid of the artifact that lumen loss was secondary. I figured if de-doming or sanding results in like a 10%-15 loss, surely partial sanding should be less, or so my logic went.

    It's hard to compare ceiling bounce without both lights present at the same time, but I should have at least taken photos but I'm looking forward to someone trying this who can take actual measurements and/or photos of before and after.

    "may you live light and phosphor" - Mr. Spark

  4. #4
    Flashaholic* degarb's Avatar
    Join Date
    Oct 2007
    Location
    Akron, Ohio
    Posts
    1,860

    Default Re: Flossing to Eliminate XHP-emitter Multi-die Artifacts

    Lux meter, not camera. . Though, I would be interested in the before and after white wall shot.

    I cannot see other people trying this approach. Maybe, they can measure the lumen drop.
    Some people are all lumens and no lux, while others are all lux and no lumens. Some just thank God they have neither.-- All of my lights have throw--some pretty darn far, into the garbage.

  5. #5
    Flashaholic
    Join Date
    Feb 2004
    Location
    Garden State, USA
    Posts
    207

    Default Re: Flossing to Eliminate XHP-emitter Multi-die Artifacts

    FWIW, some "after" photos, these would have been more meaningful if there were some before images for comparison.

    It's challenging enough getting accurate beam shots under ordinary circumstances but these images are even less accurate due to the reduced resolution (800px max) required for posting.

    With the underexposed shots the center artifact is somewhat evident.




    Last edited by pc_light; 03-01-2017 at 09:01 AM.
    "may you live light and phosphor" - Mr. Spark

  6. #6
    Flashaholic
    Join Date
    Feb 2004
    Location
    Garden State, USA
    Posts
    207

    Default Re: Flossing to Eliminate XHP-emitter Multi-die Artifacts

    It looks like the new XHP##.2 generation of emitters pretty much eliminates the need to floss entirely.

    See in the image below how the XHP-50.2 has almost no visible die separation.


    So was Cree's inspiration to fill-in the separation lines with more phosphor the result of a quest for more lumens or to eliminate the die separation artifact? - It's a welcomed improvement either way.
    "may you live light and phosphor" - Mr. Spark

  7. #7
    Flashaholic*
    Join Date
    Dec 2011
    Location
    NJ
    Posts
    1,208

    Default Re: Flossing to Eliminate XHP-emitter Multi-die Artifacts

    Richard of Mountain Electronics already built a Convoy C8 with an XHP50.2 and the cross is all but eliminated!

  8. #8
    Flashaholic
    Join Date
    Feb 2004
    Location
    Garden State, USA
    Posts
    207

    Default Re: Flossing to Eliminate XHP-emitter Multi-die Artifacts

    Couldn't find the C8 on ME's website but that's really good news.

    Gotta love these new emitters.
    "may you live light and phosphor" - Mr. Spark

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •