Improved Optics?

OK guys don't laugh too loud at me, yes this is my first post. Need a little help here. When referring to Luxeon lights I often see the term "Improved Optics" What are "Improved Optics?" I can find nothing in the Luxeon site about optics. I have 4 of the LXHL-NX05 optics, are these the improved optics?. Can the NX05 be used with the Lambertian stars and emitters? Where are you people getting the Lambertian emitters? Future electronics says they will not be out until September.

Sorry this is all questions.

I don't keep track of all the numbers & such.. But as far as I know there are two styles of Luxeon optics. The old ones are for the batwing LS's and the new style optics are for the Hi-dome.

The easiest way to tell the optics apart is that the front of the NEW style optic is TOTALLY FLAT. The old style optic is kind of "concave" on the front with a "round bump" (where the LED pocket is) down at the bottom of the "crater".

I was only able to obtain a single sample for testing as they are not currently available.

Oh yeah, Welcome to CPF

Actually, its not immediately apparent that the LXHL-NX05s are specifically intended for the HDs (BTW, the old optics part no. is LXHL-NX01 - this is the one with the nipple).

From what dat2zip and McGizmo have found playing around with the 5W HD, the NX05s are actually pretty horrid for collimating a tight beam for luxeons with the lambertian beam profile. You can use them and mess around with the focal point (as Elektrolumens has, but if I recall, he was using the NX01 for this) for pretty OK results, but it appears to be wasting far too much light at the sides. Unfortunately, no one has conclusively metered and posted the results of such experiments, so most of us here will have to wait a little more before all is known.

Over the weekend, I removed the optics from my Lambda Illuminator. Without it, there is ZERO yellow/green tint to the flood light. With the optics installed, the corona has the yellow/green tint.

I wonder if the optics itself has that tint but looking at it, that seems unlikely. I suspect that the optics is picking up the color of the yellow phospor.

- Vikas

My guess is that the optics cause color dispersion, whereas reflectors don't.

Also, I think the light loss at the sides could be reduced if Lumileds used an optical material with a higher index of refraction. What's apparently happening is a lack of total internal reflection at the sides.

Put these together, along with the ability of a reflector to give a narrower focus, and you can see why I'm more optimistic about using reflectors for the upcoming 5 watters.

McGizmo had the excellent idea of combining both reflector and optics to harness the power of the 5W, and for that matter the 1W HD. The reflectors would be great to gather all that sidespill and redirect them forwards into the optics for focusing. The optics would not really be necessary, but remember that reflectors can do absolutely nothing for the light that already blasts straight along the beam axis, so if you want a tighter beam, then a lens comes into play. A combination reflector/optics team would be the real ticket to fully realizing the potential. So far, the only example of such a combination is found in the PT Impact, which uses a single 5mm nichia, but a 5mm LED doesn't really need either. I'm sure the effect will be far more dramatic with the luxeons.

Some further thoughts/ observations:

If the collimator were acceptable seated on the LED, a silver paint applied to the exterior of the collimator surface would perhaps be sufficient in redirecting the side spill light out the front of the lens. As soon as you lift the collimator off the LED, a paint would close the door to this light.

Someone with a HD or 5W should take a hole punch and punch out a 1/4" dot of write right or LSD film and try placing that on top of the LED head and then dropping down the collimator completely over the LED. The difussion here may soften the focus enough for the collimator to work "as advertised" You may loose up to 20% efficiency here but if all the light makes it out the end, you may still be ahead of the game.

In another thread, I believe, someone mentioned using a material with a higher refractive index to keep the light in the collimator. That may help but a higher refractive index reduces the critical angle and it may be that some light will no longer be able to "get into" the lens. Obviously a polished reflector with the correct geometry should send out more light through the front but most of us wouldn't know what the geometry should be or how to get it if we did.

As the big players in illumination start bring Luxeon lights to market, I am sure we will learn of some efficient solutions; although non-spot light beams will likely be the most prevalent and we already know how to get decent flood beams.

There is agreat offer from a fellow CPF'r on another thread for making acrylic lenses but we need to figure out what the lens should look like.

Perhaps someone, again with a HD or 5W, can even try a ball with a diffusing film between it and the LED.

Whether a reflector or lens is used, If you go for a tight, sharp focus, you will get the "grill" pattern without fuzzing the light at the source. Many incandescent bulbs are frosted for this same reason. SureFires dimpled reflectors accomplish the same task, IMHO.

- Don

I don't know if other people have tried this also, but what about polishing the top of the LED like on the 5mm Nichias? It worked for a red LS that had a horrible beam pattern with either optic (the big red square with weird spots) but after filing down the top flat, it gave a nice smooth beam pattern with both optics. I probably would be too scared to try it with a 5 watt LS, but if the beam pattern is similar to the high domes, then I'm assuming it would work on those too.

Originally posted by McGizmo:
...In another thread, I believe, someone mentioned using a material with a higher refractive index to keep the light in the collimator. That may help but a higher refractive index reduces the critical angle and it may be that some light will no longer be able to "get into" the lens...

Click to expand...

<font size="2" face="Verdana, Arial">Interesting point. I hadn't thought about the light getting into the lens, only out. In this case, perhaps a material with a variable index would work, but I don't know how hard (or expensive) that would be to make.

Oh well.. I'm still hoping Lumileds will do some more R&D on this and get it right themselves. That would sure make it a lot easier on us.

PS. That reflector/lense idea sounds very promising in terms of maximizing the light output, and shaping it into a tight focus.

InThedark,

That sounds like a good idea but I don't know how thick the Lens is on the Luxeons. The batwing certainly has enough material for reshaping.

Another thought would be to take some abrasive material to the collumator interior and give it a diffusing surface. This way, worse case, you've blown an optic but the LED is virgin.

Reshaping the dome and polishing would be more efficient I believe.

Mcgizmo,
Actually, I wasn't talking about regrinding the entire LED flat and reshaping the lens, but just roughing up the lens a little like you said. It works pretty well. I haven't tried reshaping the entire lens, because it didn't seem necessary. If the lens were lexan or something, a drop of acetone would frost the lens pretty well.

Nope, the acetone didn't work

Guys, you might want to try taking some Krylon mirror finish and paint the backs of the optics. I've done it (to the older optics) and the improvements are visible. I wish I had pics, but at $11 for a set of cans, it's well worth it IMO.

According to the 5w PDF files on the Lumileds site, they'll come in Lambertian and side-emmiting versions. It seems that they have been listening to the ideas of using a reflector, or a reflector/lens combo.