I’ve been working on this idea for some time and finally feel comfortable with it.
I really like smooth reflectors, but I don’t like the occasional artifacts in the beam pattern.
What I’ve found is that most of these artifacts, rings and hotspot corona are produced very low in the reflector.
The reflector is doing it’s job…it’s reflecting the light from the emitter but is also reflecting an ‘image’ of anything that’s illuminated around the emitter…such as the isolation pad, the emitter platform, the chopped sides of an XPL and even the hard edge of the emitter opening in the reflector. One of the biggest contributors to ringyness is the horizontal portion of the reflector (if present) around the emitter.
Something else about LEDs, the light emitted from the top isn’t the same color as the light emitted from the sides. The side light is usually much greener or bluer. This off-colored side light is headed right to the lower portion of the reflector and this portion of the reflector is what creates the corona around the hotspot. What you will usually see in a beam is a hotspot that is one color surrounded by a blue/green (or yellow/green) ring and finally, the spill is back the the hotspot color. You will see, a lot of manufacturers get rid of the ‘off-colored’ side light by burying the emitter deep in the reflector…almost under the reflector. The light from the emitter sides will just shoot under the reflector. I don’t like wasting this output…even if it’s a little off color, I just don’t want an off colored ring in my beam.
Here’s a photo of the different colors coming from different parts of the emitter. Of course, the center is washed out, but you can see the color variations as the light comes out of the side…it’s following chromatic order (you know…Roy G Biv), except, you really only noitice the Yellow, Green then Blue, but if you look carefully, you can begin to see the violet.
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Orange Peel reflectors do a much better job blending the artifacts together and making them less noticeable, but to maintain throw, an orange peel reflector can’t diffuse the light too much.
What I decided to do is to modify a smooth reflector so the area where these beam artifacts are usually created (deep in the reflector) would be very diffused…not just orange peel rippled, but very diffused…so heres what it looks like (reflectors are hard to photograph, but I think you will be able to make it out):
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I created several variations that were mainly different only the how high the diffusion went…the diffused area in the photo is about twice the amount I ultimately decided on, but this one was easier to photograph.
The upper portion of the reflector reflects to the center of the hotspot and the lower portion reflects to the outer portion of the hotspot. Since the lower portion of the reflector is now diffused, the outer portion of the hotspot is now softer. The hotspot is actually a little smaller, not more or less intense…just smaller. The ‘ugly’ corona is now spread evenly throughout the beam and is no longer noticeable…but it still contributes to overall output.
So, what does this reflector do?
Well, it’s throw hasn’t changed…the hotspot intensity is still the same…the hotspot is slightly smaller and the edges are a little more diffused.
The drop in overall output is minimal…less than 2%.
It kills the corona, it removes any ringyness that starts low in the reflector but it still throws like a regular smooth. Here’s a photo a normal smooth and the hybrid smooth (same emitter and reflector… just before and after I modified the reflector)
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The reflector still has the specularity of a smooth reflector, the throw of a smooth reflector but without the ringyness and corona. I’ve decided to add it as an option on my site, but I’m not sure why everyone wouldn’t want it. Next, I will try the same thing on an orange peel reflector and see if that’s worth pursuing.
Just saved a box full of crap lights! :bigsmile: Thanks Randy!! 