I have an XP-L Hi incoming. Do the factory de-domed emitters spread more light sideways than their domed counterparts? What is the effect of the LED dome?
I ask because I have an aspheric DIY project and I am wondering am I going to lose more stray emitter lumens (radiating sideways) with a de-domed LED?
For this project I want to try a DIY Waiven collar. poor-mans deft-x if you will. Reflect all the sideways-spherically radiating lumens (stray light) back down onto the LED die to increase surface brightness. As opposed to using black paint / marker to absorb stray light inside the bezel.
I think I can use one of these hemisphere molds, drill out a hole in the center and polish it to a sphere mirror.
All else equal, de-domed emitters (including the XP-L HI) emit less light sideways than their domed counterparts. That’s the whole draw of them… a more narrowly focused beam.
Please search for the explanation from Dr. Jones regarding dedoming. It has nothing to do with the angle of the emitted light.
Also it is not advisable to use a stainless steel collar because stainless steel doesn’t reflect a lot of blue light. Blue light makes the phosphor of the LED more intense.with a stainless steel collar you will probably only get around 30 percent more intensity. A real collar can increase intensity by up to 120 percent.
An aluminium collar would be much better. Polishing it yourself will be difficult. A real mirror is better.
The HI version is not dedomed.
It just has a flat plastic surface rather than a domed one.
You can look at the emission graphs, the HI version has higher intensity near 0 degrees and less intensity to wider angles.
I think its because of the “missing” dome which would typically give any stray photons a chance to reflect back against the phosphor layer and product useable light. That’s probably not quite the right terminology… but you get the idea.
Same principle on traditionally dedomed LEDs - you gain throw at the expense of some lumen output.
Yup.
You can see from those graphs that the HI is better for aspherics.
Also remember that they are individual percentage graphs, so the 100% peak for the HI is actually more intense than the peak for the non-HI, even though they both show 100% in the center.
Just to see howe it went....the reflector is taken from a BLF A6, and it fitted just perfect down over the LED on the UF-1405.
But it was not a positive test, in my eyes....
Correct….
A parabolic reflector won’t work. The reflector needs to be a sphere… technically its a hemisphere or half-sphere. The emitter should be placed at the focal length of the sphere, or in this case the exact geometric center of the hemisphere. The hole needs to be big enough so that it allows light a straight path from the die to hit 100% of aspheric glass. An opening too small will block light, as MortyDuck discovered. An opening thats too big will waste stray lumens on the bezel/host. I would imagine its better for the opening to be slightly too big than too small.
