Aspheric Headlamp

Flashlight Modding and DIY Parts
1

Heres some pics of work in progress. I'm going to document some images of my aspheric headlamp here.

So far ive been using an aspheric headlamp for work which I had made about a year or two ago. The design goals were, in order

1) ZERO spill light

2) High output

3) Light weight

4) Aesthetic design (which comes with functional design IMO)

Came up with this

Over the year, I have modified the optics, gone through several emitter upgrades, and added the orange o-ring to fill in gaps from different optics. Referring to the original list up top.

1) Spill is quite aceptable

2) Output is only Just sufficient**, especially compared to commercial products (its more than bright enough on full, but thermally it cant maintain full (90 deg C at the emitter))

3) Definitely sufficiently light (13.5g all up including half the cable)

4) Aesthetics are simple enough.

It has the following shortfalls

1) THERMAL! it doesnt have enough surface area to cool, so it gets super hot. Running at reduced output is ok, but brightness isnt as high as desired.

2) Output is still too low. Optical inefficiency. I have 3 lenses in the light, they give a nice light with minimal chromatic aberration, but they just waste light.

So right now im making up a newer one which aims to address the issues

1) Thermal - increased surface area through incorporated fins

2) Output will be increased with a simpler single and larger convex lens with a shorter focal point. (however this lens seems to produce more chromatic aberration, and a projected image that changes more rapidly away from the focal distance (set to about 400mm)

3) weight will be increased. It already feels really heavy... :(

I've strategically positioned the part onto other torch parts around, it doesn't actually work, but woudn't that make a cute torch!!!

2

Interesting.

What do you use it for at work?

3

Optics from DX http://www.dealextreme.com/p/24mm-60-degree-secondary-optics-plastic-10-pack-4628

There is significant improvement in output over my earlier headlamp. I still need to add the matte black paint on the inside to prevent reflection of the spill light, but currently the central hotspot is as bright as as tight as the hotspot from a 1A driven R2 XR-E in a very throwy standard sized 2xCR123 superfire "10W" torch. The emitter I'm using here is a 4B tint XP-G R4.

I am yet to do real thermal tests, but so far I feel that there may be some improvement in performance, but not being able to run these side by side in a controlled environment, i wont say that its much better yet.

It definitely looks cooler though in my opinion!

Unfortunately I don't have plans for making any more, as these take 2 whole days for me to slowly machine up. I don't work fast, and this metal I have is WAYYYY too soft for my liking, it rips/tears/sticks like crazy!!! This metal wont cut threads...I managed to clean up the one on the body, but the retaining ring side just fails!. I had to use other bits of alum that I had around for the threaded retaining ring.

The optics are fixed in the design. Its meant to be used in conjunction with my magnifiers, so those give me a focal range of 300-400mm so the headlamp is optimised for that (minimised chromatic aberration, slightly defocused at that distance to smooth out the die image)

The driver is external, so the driver depends on whatever you connect this to. For me this allows me to activate the light with my elbow, keeping my hands free, especially if they are contaminated, I don't want to be putting muck into my pockets. I described the battery pack in an earlier thread a couple weeks ago. Full brightness control from probably 0.1 lumens right up to the full 100% with no visible flicker at all. Driver has full output of 700mA. Don't need any more output at a range of 400mm, seriously blinding.

4

Problem with buying optics from DX are that the glass ones are more often than not pretty average. Most are a combination of scratched, not smoooth, has defects, and may be all of the above.

Recently I've had one good one.. but the plastic ones still turn out better, and their replaceable when they get scratched.

Interms of zooming, I've found the led lensers to actually do a pretty good job at trying to make use of the spill light, while maintaining a very decent beam profile given the changing focus. I wonder if the pop lite versions are as good optically (where it actually counts). Fundamentally aspherics just suck. What we really need are long lenses for the emitter themselves. Think of 5mm leds, but having one of those really long lenses sitting atop out xp-g

5

Okwchin, nice project! I'll be following it with interest.

On a side note, I hear you about soft metal machining. I'm in the process of trying to machine pure aluminum for a project and it's a royal pita. No wonder most folks use a good alloy. Btw, what you've made so far looks great!

6

Could be tighter with an XP-E!, even tighter with an XR-E (but you see the image of the led dome/alum ring)

I guess its time for beamshots... What do people want to see this light up against? I dont have any other aspherics to compare to... and the focal range isnt the same.

I have, D10s, Nitecore Extreme, Trustfire R5A3 (first gen), Superfire thrower, Maratac AA XR-E...

7

as in.. no lens?

Or i take the lens off my headlamp?

Id imagine it would not show much. (super under exposed area, vs super over exposed spot)

8

From left to right

Headlamp - XP-G R4 4B tint ~700mA . Trustfire R5 A3 (NiMH) . Superfire 10W(model number) modded with XR-E R2 (decent thrower setup) ~1000mA

Dimension across square width of hotspot is about 45mm (or just under 2") at 400mm distance (about 16")

Lack of photo control on the phone camera means I cant control exposure. Hotspots are overexposed...

9

Fair enough. I've got the torch with the tightest beam I can find. Gives the same sized hotspot as the aspheric... lol, but remember that the emitter die on the XP-G is like double the area of the R2 XR-E, and the diameter is smaller than the thrower torch.

OH speaking of weight, I thought it was going to be way heavier... turns out its less than 3 grams heavier.

Old one = 13.5 grams

New one = 15.8 grams!

There are some artefacts in the spill area, projections of the image of the mounting screws and the soldered wires.. Everything inside has been painted black, but are still visible. I'll look into a black foam filler at some stage, for now I've used matt black hobby paint.

10

For looking into peoples mouths, without blinding them with spill light. If I was to use a normal torch, the spill light is the equivalent to staring at an emitter running full bore at elbows length! This is why the aspheric is used, to practically minimise spill light to a bare minimum, which is tolerable.

Tint could be a little warmer. The Cree emitters (as do most emitters) have warmer light out the sides, while the central output is cooler (pathway of light through the phosphor). Becasue of the aspheric lens and the cooler central light, I tend to get a cooler light than the "average" tint of the LED. I also suspect an overheating emitter so maybe I also get blue shifting after a few mins of full!! Maybe... so i never run it on full. usually around the 300mA drive region

Shiny!!

Matte Black Paint everywhere that counts.

11

this is seriously awesome!

I take it you're a dentist? you should post this on dental town

edit: Chrome/reflective surfaces actually radiates heat worse than black (black is more emissive). If you're having thermal problems, try painting the heatsink area black. It's the same reason why most loupes are black. I get that it may clash with the white heines, but function>form

12

Nice work! I think if you could somehow mount the emitter on a pedestal no larger that the emitter then most of the artifacts would go away (although I can't see any in your photo).

Black paint is OK but the optimal solution would be to get the area surrounding the emitter on a different plane so that the lens when focused only has the emitter at that point.

13

welcome!

very good advice for a first post.

I added an aluminum vga heatsink to a headlamp and just this weekend I decided to try painting it black.

The xm-l in it is getting ~3.5A from 2p 18650, so it gets pretty hot. Painting it made a very noticeable improvement.

14

I'm going to build mine with an aspheric attached to a XRE @700ma. Hopefully it'll be bright enough.

Awesome machining btw. Looks very professional.

15

Welcome to the monkey house, darkcurrent6!