The best Luxeon dome pattern for a Mag reflector

I'd like to share my experience and seek others opinions and findings re the best LS dome pattern to use for a Maglight conversion.

My experiments to-date have revealed that the side emitter kicks butt relative to the battwing (LD) and Lambertain (HD). It really is like chalk and cheese. There is no comparison. Is this other's findings, or am I fooling myself?

The side emitter, specifically a 5W LS, really does seem to collect soooooo much more light with the mag reflector than other patterns. I have found with the SE that side spill is excellent and the hot spot is awesome. The thing I found is that the side spill progressively increases in intensity as it nears the hotspot, so when used in a practical situation (walking the dog) lighting the ground over 100m seems to have the effect of a consistent 'brightness' over the long distance. Just what I want.

So, are my findings those of others - side emmiter rules for using Mag reflector, or could I be doing something wrong?

All tests have the mag reflector focusable.

Chris

With Mr Bulk's work on the Space Needle, the high dome 5Ws are actually better at throwing a tighter spot than the side emitters. The side emitters are great at spill light while offering a less tigher beam. And the low dome, well, there's no low dome for a 5W...

The 1Watters are somewhat of a different story, as I've seen the SEs perform the best with mag reflectors...

To me, the best beam is from a SE, but seems most people prefer the HD. I like all my light up front, not spred to the sides like the HD does.

I have a 2D Mag with a 1 watt SE (Lambda's Cyclops). Very nice beam. The focus is adustable from a spot to a flood. The spot has great throw and is over 4000 Lux /ubbthreads/images/graemlins/smile.gif

My experience with the 5W and reflectors is that the SE seems to spill more light out to the sides than the HD. The HD is *much* more focusable, while still having more than enough spill light around the edges to see by. I much prefer the HD, as the hotspot is more focused and significantly brighter. I don't know about the 1W with a Mag reflector though, as I usually use optics with the 1W.

On 1Watters, on my Blem-LS2, the notorious X-box beam was happy to rear its ugly head when you mated the HD with an NX05... LD was the only way to get a smooth beam out of collimators, and an SE in a AA-based flashlight was basically non-doable.

The 5W emitters have a much larger area of light, and the larger surface of the mag reflector really works well. I usually find secondary rings or coronas with a 1W SE in a mag reflector, even at its tightest spot. But the 5Ws (both domes) seemingly eliminated that.

My personal preference is for the SE, although the HD and batwing can be focused down to a tighter hotspot.

That being said, I have found ways to avhieve outstanding results with any configuration of luxeon when used with the Mag D/C reflector..

I think the difference in results achieved amongst modders could be attributed to how far the base of the reflector is cut off.. I take mine to nearly where the inside begins to open.

Looks like the SE seems to be a winner for most, but as with most things it comes down to what it is you want. Side spill, tight hot spot, or both but with a compromise to each.

I had found with the HD that the hot spot is indeed tighter, but it is a) only equal, or perhaps less intense than the hot spot of the SE and b) given the missing side spill of the SE and the only equal or less hot spot - where are the lumens going? SIt feels like someone's ripping me off some lumens with the HD.

Slick touches on something that I have found is critical with any LED and optic configuration, especially torch reflectors, and that is the placement of the LED within the reflector. It is possible to get extremely poor results of just shoving a star up to the reflector until they hit. In fact, I have found that I need to actually push the LED into the reflector some small distance, perhaps this is why Slick finds grinding off some of the reflector beneficial.

What I have done with every experiment is pop the LED emitter off the star and mount it onto a custom adapter that is basically a circular base with a pedestal raised about 4mm in the middle. It is made of aluminium and the pedestal is the diameter of the LED emitter assembly. This allows me to actually have the LED go into the reflector some distance as the mag head assembly is screwed down. It really is amazing what a difference of a mere millimeter can make when focussing these LEDs. It can make the difference between a sensational beam and a beam no one would admit to owning.

Thanks for the information all. I think that for my needs I'll stick with the SE for a Mag reflector. At least I can't see anything that would suggest I'm fooling myself with the other configurations, perhaps with incorrect set up etc. Again, thanks for the input.

Chris

I may be all wrong, but this is what I think is going on:

Lumileds documents the "spatial radiation pattern" of each type of emitter in the technical documentation available on their web site. This dispertion pattern, the reflector geometry (e.g. parabolic) and coating, and the position of the emitter relative to the reflector should completely determine the resulting beam.

The emitter types have maximum output at different angles relative to the emitter axis, and varying output at other angles. These maximum output angles are: SE - 90, LD - 45, HD - 30. For a tight beam, the reflector has to catch and reflect the most light the most accurately.

SEs theoretically should pump the most photons (90 degrees) into the reflector ... but into a portion of the reflector that's "unfriendly": not only closest to the emitter but most affected to minor variations in the incident angle. This magnifies any reflector flaws or focal point positioning errors. In other words, the SE's should put more reflected photons forward, but the hotspot may not be as tight.

HDs could pump photons into a "friendlier" part of the reflector (30 degrees) and result in a tighter hotspot ... but much of the output of the HD is in an area where there is no reflector at all--the 60 degree arc directly in front of the emitter--resulting in a tight (though not so bright) hotspot plus a wide spill ... which I (depending on application) generlly like. The Mag reflector, due to its geometry and size, happens to catch much of an HD's output.

LDs should be the best emitter for a bright, tight, laserbeam hotspot with limited spill in a reflector, since most of their output (45 degrees) is into an area where the reflector is both present and friendly. Unfortunately these are not available in 5W.

I think there is some misunderstanding here. The hotspot of the HD is FAR brighter than that of the SE if you mount it properly! You are just taking the spill light of the SE and putting most (I said MOST, not all) of it into the hotspot. The HD is MUCH better than the SE for lighting anything but the *immediate* (up to about 10 ft) area around you. Even then, I still like the HD better, and I switched out the SE in favor of the HD in my 5W mod. Plus, as it stands right now, you can get much brighter binned HD Luxeons than the SE. I switched out a U binned SE for a W binned HD.

Is there any chance anyone has beam shots of both SE and HD using identical setups and optimum LED within reflector placement?. I'd like to see what to aim for to assure myself it is done right. The question was put to the group as I am unsure of my HD's results. I expected better results for the HD than I got. The SE I tried seemed to out perform the HD in terms of all-up light output. As I stated originally the hotspot of the HD was indeed tighter, but not necessarily brighter, yet I seemed to loose a lot of spill to illuminate the ground close to me. All up (hot spot + spill) I seemed to get more light for my money from the SE, but I am willing to except the HD set-up or LED itself it not quite right. After all, even Lumileds rate the lumen output of the SE less than that of the HD so I expected more from the HD. This is why I asked. Looks like there may be something dodgy this way? (hope it's not me!).

Chris

???

Mr. Bulk is probably the authority on this subject. If you're using a Mag reflector and getting the LS focused properly, you should be getting better results than the SE unless your particular HD has some problems. Look for some posts made by Mr. Bulk about this exact thing. His webpage would also be a good place to look. It's here. Good luck.

*edit*

OK, here's the one I was mainly referring to. The HD is king here!!!

so, the best thing to do would be to start with a bare emitter, put it on a small diameter heatsink to allow it to be adjusted within the mag reflector. then yo can find a sweet spot.

correct?

i have a cyan star 5w, and i want to see what it can do with a good reflector or optics. doesnt seem easy with the star platform. should i simply open up the mag reflector a bit more, and move it in further, or will i be removing too much material and destrow the reflector?

Bob

AAhhh, just what I wanted, some pics. They tell an interesting story though. I believe the SE is the 2D. This being the case, a) the pic of the beam shots on the ceiling are deceptive. The hotspot of the SE looks to me as bright as the others, only smaller?. b) there is a lot more side spill from the SE. In the tree shots, the 2C looks brighter, but remember - less side spill.

In the lux test, the SE won, but only by a small margin. The use of the UCL lense used with the 2C HD then had the 2C beat the SE.

So what would the 2D SE be with a UCL lense? I need to know. Perhaps it would kick butt in lux as well as give the SE's side spill - a real need to see where you're walking or cycling. No use seeing what's a hundred yards ahead but tripping over something under your feet or riding over glass.

Perhaps indeed the mag reflector captures more light from an SE as Mr Bulks readings suggest (before the UCL lense mod on one but not the other). It may come down to do you want side spill or not.

It's a close call in my books and will depend on one's intended use.

Pedalinbob:

Best consult he experts here, I'm just a newbe. I can say however, I favour getting the LED spaced above the heatsink or 'spreader' over grinding down the reflector. You can then screw the mag reflector in/out to get great adjustment range. Watch out though! Whatever method you use to raise the emitter MUST have excellent thermal contact with the heatsink or 'spreader'. I call it a spreader as with the method I use the spreader (as I refer to it as) it is of similar diamater to the heatsink block, but electrically isolated from the heatsink block - which contacts the tube of the mag light (-ve battery potential). My spreader and 'pedistal' that I mount the emitter on are one in the same - machined from an aluminium rod of 30mm diameter). You must a) have excellent thermal conductivity from the emitter base to the heatsink and/or spreader, and b) the emitter base MUST be electrically isolated from any battery connection (usually negative via a heatsink attached to the body of something like mag light tube).

There are discussions in this forum on thermal epoxies, heatsinking methods etc. As a newbe I found this site very informing and I appreciate the comments, efforts and willingness of others to share their results, win or loose. It's good to see such forums where we can all share our knowlege in what is generally a very selfish world.

Just keep in mind that this one particular SE Mr. Bulk has there is probably the brightest one anyone has gotten a hold of so far that we know of on CPF. Unless you get really lucky, you will only find SE's available at about 2/3 that brightness maximum. In general, the HD's are a lot brighter, as better bin codes are much more readily available for the HD as compared to the SE. This makes it a lot easier to get a bright HD than an SE. If you can get yourself a really good SE though, than it sounds like that would best fit *your* needs.

I think that's the key - what is it you want. I do want plenty of side spill, yet a hot spot enough to throw some distance.

Frustrated with not being able to get the perceived light output out of the HD that I should have got I bought an el-cheapo light meter. It may not be accurate relative to national standards etc, but anything that measures light is good for relative measurements. Regardless of test method I consistently got more lux from the SE set-up. Based on the bin ratings of the diodes and current supplied to each, I conclude I've damaged my HD at some point in the past. The conclusions on side spill being better with the SE still hold true. I've said all along the HD gives a tighter spot.

Given the wanted side spill from the SE, I'll run with that for my dog walking torch and when I can get hold of another HD I'll suss out the spot power of these with another mod.

Thanks for the input and I'll post the finished torch in another thread if anyone is interested in the mod technique. I found the method of mods vary and each person has their own favored technique. I'll thrash (well, moderately) the SE with just under 1 amp to help get the throw I want.

Thanks again,

Chris

I remeber this came up in a previous post. Anyways, I like HD much better than SE. The beam is brighter with an HD. This might just be perception though, because the HD has such a smooth beam compared to the SE. Regardless, 1W or 5W I vote for HD.