Project Excalibur - Next Generation LED Thrower (many pics) - UPDATE 2018-01-24

I’m intrigued.

A reflecting collar could work, I think. The increase in luminance would not be as dramatic as when it’s used in a lens light though. In a lens light ~70% of the light is available to “recycle”, but only ~30% is available in a reflector light.

I am another one thats just say Wow…

Really nice build

Well 30% in 1,5milion reflector is a lot :wink: around 500kcd :slight_smile:

I’m actually thinking maybe reflector is the way to go for ultimate throw.
Lenses have a lot of chromatic aberration which almost certainly reduces the lux.

The problem is that to get the best throw, the LED intensity needs to be extremely high, and the wavien collar does massive improvements to that, over 2x.
In order to use the collar with a reflector it would need to be a recoil reflector, not a forward facing one like in normal flashlights.

Then the problem becomes the LED + collar blocking a bunch of light from the center, which is the most intense light, thanks to the collar in the first place.
.
The solution:
Off axis parabolic mirror!
-no chromatic aberration
-no blockage of light in the middle
-can use a collar to get over 2x LED intensity
.
Problem is that it would cost several thousand dollars :frowning: but still, I’m pretty sure this is the BEST method of getting maximum throw per diameter (with an unlimited budget).

Thoughts?

In theory yes, but think about it again. You would be blocking the reflected light of the reflector.

The Maxabeam Reflector used here has a 40mm “dead” hole, when used with LEDs. So that is the maximum diameter which the “reflecting collar” (this name doesn’t really make sense here, it doesn’t go around the LED) could have. The distance of the reflecting collar will then determine, how much light it collects from the LED. It would need to be just far enough away so that the light of the LED can hit even the outer edges of the reflector.

Of course most of the spill light will pass through the reflected light of the reflector and will thus never hit the “reflecting collar”. So in reality there is hardly any gain to be had here, maybe 5-10%.

Enderman’s idea to use an off-axis (main) reflector would work much better because more light can be collected without blocking the beam, but it will never be perfect and the light would probably look rather weird.

MEM from this form(inventor of that wavien collar or RA- reflective aperture how he calls it) wanted to try different approach to led reflectors and he called that RRR…

So i will quote him ” “The Recoil Recycled Reflector. Fitting? It is essentially a recoil format, in that the LED directs light directly into a “barrier” that “recoils” the energy back through the phosphor, “recycling” output back out to the “reflector” “

And you are probably right with this mirror idea cause he wanted to fit as I managed to see flat smaller diameter mirror. So his idea should really work but centering the mirror to the right distance to led will be nightmare.

Edit: He mentioned that XPG3 would be most suitable emitter for that because of all unused phosphor surface!

It is sad MEM vanished, a week after he pmmed me how sad it is when people vanish :frowning:

The best method also takes effort and cost into consideration IMHO. Half the price 10% less good = better :wink:

I spent $400 on batteries for a flashlight, does it sound like I settle for 10% less good?
:stuck_out_tongue: :stuck_out_tongue: :stuck_out_tongue:

I think a spherical reflector could be designed to capture all of the spill light for most all reflectors with typical width-to-height ratios.

Below are some rough to-scale sketches of what I am thinking.

The top reflector is a C8 reflector with 38mm active diameter, 32mm height, and ~12mm dead hole diameter. The bottom is a convoy L2 reflector, which is a bit more relatively deep, with 54mm active diameter, 50mm height, and 16mm dead hole diameter.

Let’s constrain the diameter of the spherical reflector section to be the same as the dead hole, so no light from the reflector is blocked. Then the optimal position for the spherical reflector would be as in the sketches, to just allow the LED light to reach the edges of the reflector, but capture all of the would-be spill light. Then the radius of curvature of the spherical reflector is chosen to be the same as the distance separating the LED and spherical reflector, roughly 12 and 18mm in these examples. (I’m approximating the LED as a point in these sketches for simplicity, but I don’t think a finite size LED would completely change the picture.)

I think this makes sense. Have I got something wrong? :sunglasses:

EasyB you’re correct, this is basically the reverse of a wavien collar+lens, however there are several reasons why this would be worse.

1) the main optic diameter will remain large, since the spherical reflector takes light from the middle rather than the sides.
Something I think is very important is not just getting high lux, but getting high lux per diameter of optic.
Anyone can take a big lens or reflector and put it in front of an LED to get big numbers, but the impressive thing is getting BIGGER numbers with the same diameter, or similar numbers with a smaller diameter.

2) The collar the way you drew it would only collect very little light, resulting in an intensity increase much less than 2.2x like the wavien collar does.
In order for it to be equivalent to the wavien collar, your spherical reflector would need to be collecting 120 degrees, and your main reflector would need to be much flatter and collect 30 degrees on either side.
Again, this would result in a large diameter of main optic.

3) You can see in the drawing that the parts of the reflector near the bottom are still very close to the LED.
This will be contributing to a big corona and less-sharp spot projection.
With a lens, all the surface where the light hits is farther away, giving a tighter beam and smaller spot.

What difference does a “sharp” spot make? More candela is always more candela. And the collar is doing exactly what you say - improve candela for a given optic size.

@easyb
That looks good. I guess I had an error in my thinking.

Just so you guys know - I am not actually interested in this for this light. I actually want the little bit of dark spill light it produces.

Yes it would increase the intensity, but my point is that you can get a bigger performance boost by using a different type of main optic when using a collar :slight_smile:

Another problem (I made the same drawing a few years ago :party: ) is that in order to prevent blocking the reflected light from the reflector, the mirror must be small and close to the led, so with short focal length, resulting in a larger reflected image than you want (unfortunately the led die is not infinitely small so the projection is an image, not a point), I assume larger than the die you want to project it back on.
Edit: no, it must be just as large since the source distance is the same as the projection distance. I guess??

With a spherical reflector over an LED the image is always the same size as the LED :slight_smile: just inverted.

For wavien collars it doesn’t seem to matter much which size you use (if the LED is small). The luminance gain is almost the same (the small one is more difficult to focus though).

I finally remembered to calculate this. It was easier than I thought, all you need is Pythagoras’s theorem for triangles since I already now the diameter of the reflector and the maximum focal length (94mm).

So the depth of the reflector is 73.2mm (distance from lens to focal point, straight down).
The real depth all the way to the bottom I don’t know yet, maybe an additional 15mm.

Excellent work! :student:

Congratulations! I had not seen it, thanks for sharing :slight_smile:

Thanks!

Hi Gaston,

Where is your wavien build? The Driver is making a list of furthest throwing lights in a world and your is also probably in top 20.

Hi luminarium iaculator,

Is an old thread! here it is:

It would be good to do a ranking :slight_smile: