Reflectors for the Lumileds Rebel

[Gryloc]

McGizmo,

Can you share some information about the different reflectors that you have or will have that will work for the Lumileds Rebel emitter? I have been thinking about a few of the posts you made about that new, prototype reflector for the Rebel in some other threads, and I wanted to see how and when we can attain such a reflector. Two reflectors I have in mind is this 10mm reflector that you are working on, and then your older McR8 reflector. You have some more stock of the McR8 reflector at the Sandwich Shoppe.

How well does the McR8 work? Do we have to remove any material from the back for it to sit lower on the Rebel and focus? I heard it worked with some Nichia emitters, so I figured the Rebel may also work, possibly.

Now you said that since the die of the Rebel is so low (right above the ceramic substrate package), you almost have to put the Rebel emitter on a pedestal and almost put the entire emitter package into the hole for it to focus with any other reflector (IMS series and the existing McR line). Is the beam desirable with the Rebel and these larger reflectors, even when focused? You mentioned that small reflectors with proportionally large dies will give a larger, but even hotspot. Maybe you can elaborate more on this for everyone else. It is very interesting information! Maybe you can make the comparison with the Lux V in a 20mm reflector.

I wanted to mod a small light with one of these reflectors, using the Rebel, and I wanted to make sure everything will work okay, even if I have to do some modification to the light and/or reflector. Thank you!


-Tony

 

[McGizmo]

Hi Tony,

I am not well versed with the Rebel at this point. The last samples I got were in the 60 -80 lumen range if I recall correctly and beyond some preliminary investigation, I was not inclined to delve further in these until I received the higher flux samples and confirmed that they were "as advertised". When I get back to Maui, I expect some of these to be waiting for me.

I can try to find the time to do a beam shot comparison between a KL4 and the rebel behind the 10 mm reflector. To the naked eye they are very similar to the point of looking like they come from the same source. A photo could catch the differences.

The McR-38 is not in stock anymore and I am not inclined to purchase 300 - 500 of these on "spec".

There are a few challenges in working with the Rebel as have already been identified. One is the SMD mounting issue and the other I see is the asymetric package lacking any concentric reference point for mounting beyond the gummy dome itself. I believe the Rebel near demands flow mounting to a PCB that is either metal core or one with good via thermal relief. Further the PCB itself is best designed if it provides for alignment reference. I have a few round MCPCB's that were laid out for the Nichia Rigel and they can be modified to host the Rebel but the modification is a PITA and these boards are .750" in diameter. I believe Wayne has some smaller PCB's in the works.

When I get back to Maui, I expect I will be sending inventory of the McR-10R to the shoppe. I can also mate the sample Rebel up to some of the larger reflectors but I don't expect any surprises. I believe the Rebel will perform much in the same manner as the Luxeon and Seoul P4's in similar sized reflectors. I believe that in many configurations, one will find that the LED lead wire solder points will be in physical conflict or interference with the bottom end of the optic one has planned on using.

To my knowledge, The new K2 uses the same die as that in the Rebel. It has been my experience to date that the Rebel is at the low end of Vf in comparison to the other high power LED's and yet the K2 has been significantly above the others?!?! For flashlight modifications, I think the K2 is better suited as a retro fit but only if it comes in line performance wise. A design based specifically on the Rebel can overcome the problems one is likely to face in a retro fit mod.

Given the utilitarian beam pattern I perceive with the McR-10R, I am interested in a 7UP configuration using the Rebel as I think one could have a very viable and small flux intense, light source. The McR-10R seats down on the Rebel package and I used some UV curing adhesive to bond the sample I am working with. The reflector has such small mass that I believe bonding it directly to the LED is a reasonable, if not ideal, approach. :shrug:

I'll try to bring some photos and quantitative information to this thread when I get back to Maui and find the time to do so.

One final comment is that on thermal issues. The 60-80 lumen part I have messed with does put out the heat one would expect and the .750" MCPCB seems to pull this heat out reasonably well. A higher flux part will generate that much less heat. Regardless, the Rebel is so small that the design or mod will really need to be effective at the source in a good thermal contact and passage provided.

 

[dat2zip]

I know the Rebel is going to be a real PIA to mount. Just got confirmation that the 10mm thin PCB we just made for the Rebel shipped and should be hear early next week. These mate with Don's 10mm reflector or can be used to mount the Rebel on.

Once mounted on the thin PCB the Rebel+thin pcb can be glued onto any pedastal, heat sink.

Here's a picture of the layout of the PCB.

The backside is solid copper and the vias connect the thermal pad to the backside.

Wayne

 

[Kiessling]

I see very bright and very small lights in my hands in the near future ...

 

[luxlunatic]

I see very bright and very small lights in my hands in the near future ...

Oh yea! Or, how many McR10's can you squeeze into a Mag head?

 

[Gryloc]

Thank you McGizmo! Take your time and enjoy your time away. I did not expect very much extra from using a standard reflector with the Rebel.

I was wondering about your old McR-8, though. It is 2mm smaller, but it has the 3mm opening and could work with the Rebel. With that reflector, will it focus with the Rebel? If not, can it possibly focus with the Rebel with some modification (material removed from the back)?

Can you tell us if you will think about making a bigger reflector for the Rebel if this "McR10R" will be a hit? I can imagine a 20mm or even 27mm reflector with the tiny 3mm opening for the Rebel. That would be amazing! The smaller reflectors are still great though. I can image the equivalent of 7 LuxV's w/ 20mm reflectors crammed into the typical 30mm diameter flashlight, but running at half the power. . Yeah, your 7-up in a small flashlight. Wow.

Over time, the CPF community will easily figure out how to mount these reflectors, also. I seen some resourceful members create McR reflector holders in their tri/quad lights. If the reflector truly has that little of mass, then I am sure that glob of epoxy will do fine, too. By the way, I believe that Lumileds explains how to perfectly center the Rebel by using those two special printed dots as reference points. This is good for those using machines to surface mount the emitter, but may be as useful to those that are hand-soldering the emitter.

Dat2zip, great idea. I am sure that you communicate often with Dat2zip to co-ordinate products like this. That board looks pretty solid with thermal transfer.

By the way, luxlunatic, I think you can perfectly fit a nice looking cluster of 19 10mm boards and reflectors in a 50mm diameter circle. The head of a 2D mag is ~48mm, so someone can easily bore it out to over 50mm. That will be such a beast if you can only feed the Rebels that much power. You know what? We might have to contact the guys who build the ROP Mags and ask them how to deliver that much power! Can you say 1900lm at 20W, 3300lm at 43W? :shakehead Incan dudes, watch out!

Pictures and beam shots are more than welcome, of course! Comparisons are awesome, too! I cannot wait. Thanks again!


-Tony

 

[McGizmo]

Tony,
I won't try to explain the geometry of a parabolic surface in this response but if you wanted a reflector that had a tiny hole in it for the LED and if you want the LED to be focused then this dictates a short focal length curve and asking for a specific OD of the reflector just tells you how deep the reflector wil be so that it grows to that 20 mm diameter. In the case of a Rebel for instance. the reflector would essentially share the same curve as the McR-10 but just be a much deeper version of it that would grab more of the light and reduce the spill while adding intensity to the spot. The spot would however still diverge and be a large spot.

Just because the dome of the Rebel is small doesn't mean that the whole diameter can be small if you are after a tight and bright collimated beam. When it comes to the geometry of the beam, it is the size of the die that dictates and not the size of the package. The Rebel does not have a smaller die than the XR-E or Seoul P4.

 

[AndyTiedye]

Think someone will sell Rebels on little stars?

 

[cave dave]

I think the reflector in the Mule will work just perfectly. Heck you could fit several Rebels in a 1" dia light!

 

[Gryloc]

Has anyone bought and tried this reflector? Anyone able to post some pictures and beamshots? McGizmo, could you post pictures and maybe give us some more details on this reflector (such as dimentions, etc.)? That would be very helpful. Thank you!

-Tony

 

[dat2zip]

We enabled the rebel thin pcb (no pics, limited description) for now on the shoppe here.

Also, we enabled the rebel flower thin pcb, rebel 10mm reflector, again, no image, basic description. When we get a chance we will get photos up and provide more information in the desciption section.

The last picture shows the loaded Rebel flower PCB alongside a McR17 for reference.

You can with some care reflow the Rebels on the thin PCBs using a soldering iron. It's easier on the 10mm vs the flower, but, I had one on the flower that had a short from the anode to cathode with too much solder paste underneath. I was able to heat with a soldering iron adjacent to the thermal pad and then remove the LED, clean up the pads and then reflow the LED back on with the soldering iron.

Wayne

 

[Neg2LED]

Now THAT looks cool. Thinking about it, you could probably fit 5-across of Rebels and 10mm reflector in a maghead....

Sweet.

--neg

 

[McGizmo]

Has anyone bought and tried this reflector? Anyone able to post some pictures and beamshots? McGizmo, could you post pictures and maybe give us some more details on this reflector (such as dimentions, etc.)? That would be very helpful. Thank you!

-Tony

Tony,
I am waiting on some of those thin PCB's from Wayne so I can do some playing myself. I did upload the dimensions of the McR-10R in PDF format, HERE. Because I have noticed a very similar beam pattern between the SF KL4 and the Rebel with McR-10R, I would like to build up some simple host and compare the two with beam shots when I can.

Should I decide for what ever reason to get more involved with the Rebel, I think an obvious additional optic to experiment with would be a deep version of the McR-10R. That is to say take the same focal length in the 10R and extend the reflective surface in a deeper and larger OD reflector, much as I did with the McR-20 taking it to the McR-27L. For instance a McR-15R would have a deep reflective surface with reasonably tight exit or spill angle. It's all academic at this point.

 

[Gryloc]

McGizmo,

Thanks for the information. Lets hope things go well for you with these reflectors. You know, I was wondering when larger reflectors would come out for the Rebel. I think I asked a question like that, but it came out all wrong. I do not know. I was thinking just about a deeper reflector with a similar parabolic curve. A McR15-R would be more than welcomed! Lets hope for the same with the rest of the CPF community. I was worried by just how shallow the reflectors would be for your McR10-R. I don't know. I guess look at the 27mm IMS. It is very shallow, but has a good beam. Have you thought of playing with the same curve and making a 20mm or even 27mm version of that (strictly prototypes for fun). That would be interesting to see the results. No matter what you make, those small 10mm reflectors will become very valuable for all those AAA and key chain light makers, or for those wanting a super-mini 7 LED light that is a bit more than 1.3in in diameter. Finally, do you plan on releasing any smooth reflectors, or at least a reflector with extremely minimal stipple? With LEDs getting better, we may need less blending for our hot spot. I always wondered what type of throw some of the McR reflectors would have id they did not have the stipple (though it is great with). Just a though...

Well, McGizmo and Dat2Zip, keep up the great work. It is great seeing new products come out. I just aquired a variety of Rebels myself, so when I get the $, I will have to invest in quite a few of those McR10-Rs and the emitter boards. Thanks...


-Tony