# Road friendly light design



## mfj197 (Jan 28, 2011)

I'm designing a lighting solution for my commute to work, and am seeking the ideal of a beam that provides a lot of light on the ground but doesn't blind other road users or waste light up into the air. To repost my words on the XM-L thread:


> With the advent of more and more powerful emitters the issue of reducing glare to other road users is becoming more of an issue. Not only that, but also it is more efficient to put the emitted light down on the road where it is useful rather than shine it up into the sky. The lights are now powerful enough to usefully see by, rather than the weedy things of past which were only good for being seen. Even a single P7 emitter is pushing the boundary of what's acceptable on the road if it is not controlled properly. However <snip> in the wet you really do need a lot of light hitting the road surface, especially if there are commuter cars all around adding to the glare.


The beam provided by a powerful flashlight does a good job of lighting up the ground, with the gradual change from spill lighting up the road nearby to throw projecting light further down the road. However it does an equally good job of lighting up the air and trees around, so surely those lumens could be better utilised in providing yet more light on the road?

A car headlight has to blank off half of the light to achieve a road-friendly beam. This is because the emitters, be they halogen bulbs or HID, emit through 360 degrees. We are using LEDs which only emit through 180 degrees with quite a sharp cutoff, so surely we can be clever and use all that light where it is needed?

One idea is to in effect use just half a flashlight, with an emitter firing down into a parabolic reflector as below:








This could work well, with the beam changing from focussed (part of the LED is at the focal point) through to wider flood (part of the LED behind, like a defocused Maglite). However it is quite difficult sourcing an aluminium parabolic reflector that is designed for an incandescent bulb not an LED, and which has a very narrow opening behind the focal point as I don't want to waste light out the back. It has to be a reflector designed for an incandescent bulb as reflectors for LEDs are normally cut off at the focal point, like thus:








The next idea is to flip the design vertically and move the LED forward, which is very similar to the way a standard halogen headlight in a car works. There the dipped beam is effected by having the bulb element in front of the focal point, and a shield preventing light emission down into the bottom part of the reflector. The design would be like this:








Either method requires cutting a reflector in half of course, but will give very good heatsinking as the LED star can be attached directly to a flat heatsink on the case. I've tried some beamshots with a Maglite plastic reflector and small LED, but have just received an XM-L through the post so will try and post some beamshots using that.

Another possibility, which I haven't any diagrams for, is along the lines of a projector headlamp. In that, the LED would be placed at the focal point of an ellipsoidal reflector, firing up in the same way as just described. The ellipsoidal reflector would refocus the light which would then pass through an aspheric lens, tightening the beam. This is the way car projector headlights (halogen or xenon) work. The only problem is the smallest ellipsoidal reflector I've found is 2 inches across, so the light would need to be a 2 inch tube from back to front (although the lens can of course be smaller). A cylinder 50mm across, 100mm long is probably a bit large for a single emitter light!

The wikipedia article on headlamps has good background information.


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## mfj197 (Jan 28, 2011)

p.s. As a teaser here's a kit of parts I used for some earlier trial beamshots!


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## mattthemuppet (Jul 16, 2004)

[URL="http://www.cateye.com/en/product_detail/462']Cateye[/URL] have an interesting take on this - 2 1W LEDs back to back at the front of the light aimed backwards to shine onto the reflector. Had a play with one in my LBS by don't really have any real world experience with one


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## HakanC (May 12, 2007)

Here is an interesting site for road friendly lights
http://www.xs4all.nl/~swhs/fiets/tests/verlichting/index_en.html


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## brad72 (Jun 12, 2009)

I've been playing around with reflectors and the like for some time but just can't seem to get a good cut off with a small optic and still achieve a high efficiency . I've looked at lenses designed for HID but their diameter is around 3 inches and the focal point too far away making the light about 5 inches long. 

I have a 1200mm x 2400mm sheet of acrylic mirror that I have been bending into different shapes but the reflective coating becomes dull as soon as the slightest bend is introduced. Perhaps I need to try and cut small wedges and join them together. 

So far the perfect road light seems to be the holy grail, just out of reach.


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## black_box (Feb 15, 2010)

brad72 said:


> So far the perfect road light seems to be the holy grail, just out of reach.


Check out the dynamo powered lights on the link posted above, the good ones seem to have the cutoff and beam shape set up well for road use and the consideration of other road users  The philips light is ~100 british pounds? so $160 US. Add a dynamo for $30-50 and you have a battery/charger-free solution (assuming you can build your own wheel).


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## emu26 (Jun 23, 2008)

Nice work mfj, the pictures make it so much easier for me to understand what you have been talking about elsewhere. 

I'm eager to see how the beamshots work out. Given that this is for a commute I'm guessing the light will be bar or bike mounted so a loss of intensity isn't such an issue as the extra weight of adding a second, or third LED and the battery to drive it isn't as noticeable as it would be on your head. Obviously the key here is getting the beam exactly the way you want it.

Now for a bit of a grey area, the focused beam will be great when the road is flat but what about as you crest hills, this will presumably put a very intense beam at eye level of oncoming traffic and when you hit the bottom of the hills and flatten out it will give you a very bright hotspot very close which might effect your night vision. any plans on how to combat these issues?


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## mattthemuppet (Jul 16, 2004)

emu26 said:


> Now for a bit of a grey area, the focused beam will be great when the road is flat but what about as you crest hills, this will presumably put a very intense beam at eye level of oncoming traffic and when you hit the bottom of the hills and flatten out it will give you a very bright hotspot very close which might effect your night vision. any plans on how to combat these issues?


gyroscopes/ accelerometers plus servo controlled mirror, a la BMW motorbikes?


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## mfj197 (Jan 28, 2011)

HakanC, thanks for the link - some very good discussion and reading there. I have wondered about modifying an existing light before, and possibly the Philips LED Bike Light could work very well. It seems to fire a pair of LEDs down into part of a parabola, confirming there may be mileage in that approach if I can get hold of a suitable reflector. My one concern with these lights is they are almost too effective - they light a track ahead of the rider with hardly any spill to the side, which can lead to accusations of the feeling of riding along a tunnel.



emu26 said:


> I'm eager to see how the beamshots work out. Given that this is for a commute I'm guessing the light will be bar or bike mounted so a loss of intensity isn't such an issue ...


Well, to be honest I'd expect no loss of intensity - in fact I'd be hopeful of a gain in intensity of light striking the road. As an example the Philips LED Bike Light referred to above, with only 270 lumens, puts much more light on the road than single P7s or triple XPGs and is apparently comparable in usefulness to the 2011 Lupine Betty with 7 XPGs and 1850 lumens.


> Now for a bit of a grey area, the focused beam will be great when the road is flat but what about as you crest hills, this will presumably put a very intense beam at eye level of oncoming traffic and when you hit the bottom of the hills and flatten out it will give you a very bright hotspot very close which might effect your night vision. any plans on how to combat these issues?


I think having a beam optimised for a flat road will probably be acceptable. I tend to ride with a small helmet light anyway which can provide a bit of fill if necessary. Regarding dazzling oncoming traffic as I crest hills I can take a leaf from the automotive industry. HID headlamps here in the UK are recognised as being very bright and by law have to have both headlamp wash and self-levelling. However the self-levelling is purely to counteract differing loading of the car - it doesn't counteract hills, so I don't think I would bother with trying to develop an approach that could. Interestingly of course this is one reason I need a good bike light, as the constant stream of traffic cresting the undulating road does dazzle!


> gyroscopes/ accelerometers plus servo controlled mirror, a la BMW motorbikes?


Methinks you doth expect too much from me!


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## bravellir (Nov 24, 2008)

mattthemuppet said:


> gyroscopes/ accelerometers plus servo controlled mirror, a la BMW motorbikes?


Or just flesh and bones.  When I'm in the road I usually use only the helmet light and I just look slightly down/right when there is incoming traffic.
But it's not as cool as some servos :thumbsup:

What about if instead a single large LED with a modified beam, we used a few smaller less powerful led and individual lenses with narrow beans. Would it be possible to point these individual beams so that they hit the road in a long and narrow rectangle?


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## emu26 (Jun 23, 2008)

bravellir said:


> What about if instead a single large LED with a modified beam, we used a few smaller less powerful led and individual lenses with narrow beans. ?


I don't think the beans will be much good for throw unless we're talking about a rear light.

On a serious note, whilst you may get the same intensity of light with more leds at less power I don't believe you'll get the same throw. Those extra lumens from the additional LEDs don't magically start at the furthest edge of the original LEDs, if that makes sense


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## mfj197 (Jan 28, 2011)

bravellir said:


> What about if instead a single large LED with a modified beam, we used a few smaller less powerful led and individual lenses with narrow beans. Would it be possible to point these individual beams so that they hit the road in a long and narrow rectangle?


I guess that's what I do at the moment with a couple of cheap flood-to-throw zoomable flashlights with aspheric lenses. I use one aimed down on flood (nice, no hotspot) and one zoomed further in pointed nearer the horizon. It is much more acceptable to others than the P7 flashlight I also sometimes use. But it's not perfect by a long shot - the intensity of the flood light quickly diminishes until it meets the spot of the zoomed light. The zoomed light itself is providing quite a narrow beam as well, not emitting out to the sides. Plus at the end of the day they're not that bright.


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## bravellir (Nov 24, 2008)

emu26 said:


> I don't think the beans will be much good for throw unless we're talking about a rear light.
> 
> On a serious note, whilst you may get the same intensity of light with more leds at less power I don't believe you'll get the same throw. Those extra lumens from the additional LEDs don't magically start at the furthest edge of the original LEDs, if that makes sense


 damm spell checker

I was just adding to the discussion. What I was imagining was some sort of 2*3 array off +-200 lumens leds. 
Imagine a 7Up.. and some kind of optic that produces a group of beams that instead of being parallel, each beam would focus on a determinate distance ahead. Like mfj197 did with his 2 lights but with more leds to avoid the gap between the spots.
I know that it won't be as bright as a single led, but on the other hand, less lumens would be thrown away where they aren't needed.


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## mfj197 (Jan 28, 2011)

Nearly finished the test rig yesterday now the XM-L has arrived - just need to source some thermal mounting tape and a switch. Out in the garden yesterday I briefly tried Option 2 above (LED firing upwards into half a parabola) with the dissected Maglite C/D reflector. Seemed to be very effective indeed, with a clear cutoff and putting much more light on the ground than my Spiderfire P7 flashlight. No beamshots yet I'm afraid.


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## HakanC (May 12, 2007)

mfj197 said:


> HakanC, thanks for the link - some very good discussion and reading there. I have wondered about modifying an existing light before, and possibly the Philips LED Bike Light could work very well. It seems to fire a pair of LEDs down into part of a parabola, confirming there may be mileage in that approach if I can get hold of a suitable reflector.


Yes it does, it looks like your 1st picture








but its got 2 Rebel LEDs, side by side.



> My one concern with these lights is they are almost too effective - they light a track ahead of the rider with hardly any spill to the side, which can lead to accusations of the feeling of riding along a tunnel.


Because of alla the snow in Sweden I haven't tried the Philips LED Bike Light (LBL) much, but there is som spill for sure.
The drawback with the currebt version of the LBL is its bad electronics and lack of a contact for external power.
But I will try to modify mine anyway.


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## jellochaos (Mar 7, 2011)

I am really interested in this thread.
I was searching for reflectors such as those of the philips bike light has but I haven't found anything. Instead, I found these.
http://blogsci.com/science/how-to-make-a-silver-mirror
http://www.make-stuff.com/formulas/mirrors.html
So.. If you can't buy it, make it.


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## mfj197 (Jan 28, 2011)

Interesting reading / viewing jellochaos. How would you go about creating the parabolic reflector substrate to deposit the silver on?

Had a good session out with the test rig a few nights ago using the stock Mag C/D reflector above. Method A, firing down into the reflector from behind the focal point, was more effective than expected bearing in mind the large 15mm dia hole at the back of the reflector. It produced a beam with throw and good cut-off, with the beam lighting all the way to the front wheel (spill from the LED). However there was quite a bit of light lost out of the hole in the back.

Method B, firing up into the reflector from forward of the focal point, put more light out of the front and threw very well again with good cut-off. The downside was the beam ended some 6-8 feet or so in front of me, with no light closer. This is of course because the only light reaching the ground is coming from the reflector, as any spill is lost upwards. Moving the LED forward brought the beam closer but at the expense of throw and beam shape.

I was surprised at the effectiveness of Method A. I've ordered an aluminium smooth Mag reflector with an 8mm hole to carry out some more experiments, and I also have an orange-peel reflector from a xenon P61 drop-in to try out when I've cut it in two. I might not be able to get in behind the focal point on this P61 reflector as it's 1" in diameter, but might work well using Method B. Shame it's O/P though - I can't find a smooth one!

Beamshots when I get my camera back and when new reflector arrives.

HakanC, is the reflector in the Philips aluminium or plastic?


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## jellochaos (Mar 7, 2011)

I was thinking of making a parabolic shaped substrate from the plastic used in CDs, then silver it. But every time I have tried to bend a clear plastic with heat, it always turns opaque or loses its transparency in some other way. I could bend it and deposit the silver on the outer side but it will tarnish.
It sounds really difficult..
But you had good results with available reflectors so I will also order some to experiment.


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## HakanC (May 12, 2007)

mfj197 said:


> HakanC, is the reflector in the Philips aluminium or plastic?


(Sorry for my late reply.)

I think the reflector is plastic, but metalized or aluminized (is that english?)

/Håkan
SWEDEN


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## jellochaos (Mar 7, 2011)

mfj197 said:


> Beamshots when I get my camera back and when new reflector arrives.


So... Can we see any pictures? I am really curious to see your results.


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## mfj197 (Jan 28, 2011)

jellochaos said:


> So... Can we see any pictures? I am really curious to see your results.


The current status is I have a number of reflectors to cut in half and mount on the testbed. They are:

Litho123 reflector for Mag C/D - 52mm smooth aluminium
P60 incandescent dropin - 26mm orange peel aluminium
Underwater Kinetics 4*AA - 23mm smooth plastic
It's a shame the P60 dropin isn't smooth but I haven't been able to find one that is, excepting ones for LEDs which as mentioned above are no good. I was hoping the Underwater Kinetics reflector would be aluminium but it isn't, and it might be a bit small.

Unfortunately I don't have any pictures just yet, and won't for a couple of weeks (first child due to be born in 6 days so rather busy!). The initial tests with a plastic Mag reflector were extremely encouraging. Will post pictures when I can!

Michael


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## mfj197 (Jan 28, 2011)

Apologies for the delay to this - the baby and necessary DIY have rather taken over! Anyway, managed to get some indoor beamshots today and hopefully some outdoor ones soon when I've found a suitable location.

Firstly the test kit:


The beamshots here are from the two aluminium reflectors, the excellent Litho123 Mag reflector on the left and the P60 orange peel drop-in.

Here's an animation of the Litho123 reflector, moving from having the LED behind the focal point to in front. The beam starts off below the cut-off when the LED is behind the focal point, as in the first method in the initial post (I'll call it method A).








Both methods could work. With method A most of the light is directed under the cutoff, including the spill. Method B would have to be inverted of course, and the spill is then upwards so outside the semicircular cut-off close to the front wheel may be a problem.

What's interesting is that the beam can be tightened up by moving the LED in the vertical plane as well. For method A, moving the LED further up and away from the reflector, and for method B moving the LED further up into the reflector has the effect of tightening up the beam as follows (method A first):


And method B:


Finally, here's a couple of shots with the P60 reflector. It is such a shame I can only find orange peel ones as I really need a smooth one! Method A:


And Method B:


Michael


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## mfj197 (Jan 28, 2011)

Latest (zany) thought - LED mounted in the traditional orientation but the reflector cut and the top half moved aft, so the bottom works using Method A and the top using Method B, as in the following picture. This might mean I can use the smaller smooth reflectors that you guys are using elsewhere, rather than the 50mm monsters I currently have!


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## mattthemuppet (Jul 16, 2004)

only issue with that approach is that you'll still have the direct (non-reflected) light from the LED itself, which is the issue with normal reflectors. Could be solved with a hood, like others do, but I still think your original approach is neater.


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## Bobblehat (Dec 1, 2007)

:thumbsup: Good stuff! Thanks for showing us the results of your experiments. I can see a very nice road beam coming at the end of this!


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## mfj197 (Jan 28, 2011)

True, matthemauppet, but the only light above the horizon would (probably) be that direct light from the LED rather than any light from the reflector, whereas a standard reflector aimed horizontally has a fair amount of reflected light above the horizon. I'll get a Regina or two to cut up and see, but to be honest I think you're probably right - the original methods might be best.

The reason I need a sizeable reflector is most of the light is being reflected from fairly close to the LED, and that's where the issue with the XM-L being far from a point source of light comes into play. It makes the beam more floody than otherwise, although I think I can get pretty decent throw with the 52mm Litho123 reflector.


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## Riken (May 27, 2008)

food for thought. Lexus LS600h

https://smg.photobucket.com/albums/v496/20EVOLUTION01/LS600h%20Stuff/?action=view&current=LS600hL-2.png

https://smg.photobucket.com/albums/v496/20EVOLUTION01/LS600h%20Stuff/?action=view&current=LS600H.png

https://smg.photobucket.com/albums/v496/20EVOLUTION01/LS600h%20Stuff/?action=view&current=600h_LED.jpg


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## Magnum9 (Jun 8, 2011)

Dragging up an old thread I know, but I am also interested in creating the ideal road beam. Your ideas have hit the nail on the head, have a look at the Roxim rs3. It uses a single emitter at the top shining onto a compound parabolic reflector to achieve an almost perfect spread of light and comply with the new German standards. I have one which I am going to see if I can get apart without destroying it. On full power it is rated at 30 lux and based on the poor battery life from the 2 AA's I reckon it pulls around 1 amp.


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## mfj197 (Jan 28, 2011)

Magnum9, coincidentally I was looking at your thread and looked up the Roxim RS3 early this morning! Fitting a more powerful emitter in that could well work nicely, assuming it can dissipate the heat that something like an XM-L produces. I've seen another couple of lights which work in similar ways; the Philips LED Bike Light of course, and the Trelock LS 950. Of these the Philips is the most impressive; nominally 80 lux and I have been tempted to modify one - if only it wasn't so shockingly ugly, and expensive to buy just to take apart! Be interested to hear your experience of taking your Roxim apart if it proves possible.

I'm very envious of your access to the CNCs! Seeing as I'm using what are effectively upgrades for a Maglite I think I'll probably need to go with half a Mag head attached underneath a heatsink for each light. Still open to ideas on that one, and I still need to assess the exact position of LED to the reflector. It seems to work best if backed out a little above the reflector, narrowing the spread of light on the road ahead.


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## Magnum9 (Jun 8, 2011)

In theory I could machine up a compound reflector from billet aluminum but I don't have the design skills or software to do it. Plus it would take some tedious hand polishing to make it work. Over the next few days I will check out the Roxim.


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## HakanC (May 12, 2007)

mfj197 said:


> Of these the Philips is the most impressive; nominally 80 lux and I have been tempted to modify one - if only it wasn't so shockingly ugly, and expensive to buy just to take apart!


I have modified my Philis LBL to use a MS900-battery
More about that here: http://www.candlepowerforums.com/vb...D-bike-light&p=3620285&viewfull=1#post3620285


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## Magnum9 (Jun 8, 2011)

I had another thought on this. Rather than trying to 3d mill a compound reflector I could turn up a full parabolic reflector then just mill off one side like you have done. That way it would have no hole in the back either. Is there any modeling software that will show the expected light pattern for a given reflector?


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## mfj197 (Jan 28, 2011)

I'm afraid I don't know of any modelling software, at least not free (and I can't really justify purchasing something). However turning a parabola yourself would certainly give you the advantage of being able to tune it exactly to what you want, and to have no hole in the back as you say. I'm not losing a great deal of light through that hole but it is still there - I think I'll machine some solid aluminium to fill it to make sure all the light goes out the front.

Interesting mod to your LBL HakanC. Shame the electronics still cut out after 45 mins, but sounds like you have that covered when you use the TaskLED driver.


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## Rekkie (May 26, 2011)

Have you looked at the technique of those aspheric-type car headlights? I have one lying around that I take apart and post some pics if you like?


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## mfj197 (Jan 28, 2011)

Thanks Rekkie, I have indeed - and actually I have an HID headlamp from a Mini Cooper S sitting in the garage at home that I might dismantle. What's your headlight from?

That method requires an ellipsoidal reflector rather than a parabolic one, and the smallest I found when researching was 2 inches (50mm) in diameter, with a distance between the focal points also of 2 inches. (There are 2 focal points with an ellipsoidal reflector as it takes the light from one point and refocusses it at another, after which it subsequently passes through an aspheric lens in front of this second focal point.) So any light based on this would be a tube, 2 inches in diameter on the inside, and probably 3 - 4 inches long, with quite a heavy aspheric lens. That's possibly getting slightly too large? Tough call as it would probably give a good beam.

Riken's good pictures earlier in the thread show both this method (for the main headlights) and the LED-firing-down-into-half-a-parabolic-reflector method.


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## Rekkie (May 26, 2011)

The one I have is for an Astra (Opel / Vauxhall), picked up after some guy wrecked his car up my road. Took a quick measurement, seems this one has a 70mm glass aspheric, and 130mm from the tip to tip in length and it's fairly heavy as well. But it is composed different to those that Riken posted.

Although a HID bulb, it has a vertical profiled part blocking the bottom half of light reflected from the ellipsoidal reflector, giving that angled beam shape.


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## Riken (May 27, 2008)

can't u just put a shield to cover half the opening of a fraen reflector?


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## Rekkie (May 26, 2011)

Just tried it with a stock D-Maglite and it kind of does the same thing that the half-Mag reflector above does, only the light is substantially dimmer.

Will take apart the car headlight and see what it does when I add the asperic...


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## Rekkie (May 26, 2011)

Ok, so I split the too pieces of the car headlamp and shined the stock (Krypton bulb) mag through the aspheric...










Looks promising!!

The headlamp:


















Hope it helps...


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## brad72 (Jun 12, 2009)

Ok, so in the aim of a perfect road lamp I have cracked it as you can see from the beam shots below. I am using my triple xml with medium triple optic powered at 2800mA and an aspheric lens with cutoff. The only downsize at the moment is the size but there is definitely a perfectly clean cut off of light and no upwards glare.

Triple xml by itself










Triple xml with cut off and aspheric


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## mfj197 (Jan 28, 2011)

Looks good brad72. The horse in your field would be slightly less startled if you shone that at him! How have you used the aspheric and cutoff with your triple? Any photos?

Rekkie, thanks for the teardown of the light. It looks like it is an HID for low-beam only (separate light for high-beam), so has a fixed shield to effect the cutoff. The one I have looks a similar size although it's what they called a "bi-xenon" headlight, i.e. the cutoff shield moves out of the way with a solenoid to effect high beam. We of course could make do with only half the reflector and the LED firing up into this for low beam, so no lost light. Shame about the size and weight though. Are you tempted to try and make a light out of it?

Riken, the biggest issue with using a shield over a reflector is that you are immediately losing half the light emitted by the LED. Brad72's beamshots show that quite well. It should be possible to be a bit cunning as our LEDs only emit through 180 degrees rather than the 360 degrees of a bulb. There's also the issue that a shield in front of a reflector will only cut the spill, but the circular nature of the hotspot will (normally) still exist as it is a not particularly clear image of the LED itself, and is being transmitted from the top and bottom of the reflector. That is unless you move the shield even further over the front of the lens whereupon even more light is prevented from coming out.

Having said all that, there is probably a point where the increased weight and complexity of a mechanism to harness all that light outweighs the additional weight of just adding more LEDs and cells in the knowledge that half of the emitted light is being wasted. But from a principles point of view I'd like to put as much light on the road with my twin XM-L setup as a quad XM-L with standard optics can!


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## brad72 (Jun 12, 2009)

I'll post some shots tomorrow but all i can say is that it is the biggest and ugliest thing i have ever seen. It was more of a curisity thing that has been niggling away at me for some time having experimented with Cut up reflectors and the like for some time.

I used an aspheric assembly from a range rover headlamp which my father donated to the cause after obliterating a bush turkey at 120km/h. By aiming the triple xml upwards towards the top of the back reflector i was abld to increase the light output quite dramatically. Not using any optics gave next to no light and a horrible beam but the triple medium optic made it look great. 

Next to make it about 20 times smaller


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## Rekkie (May 26, 2011)

> Originally Posted by *mfj197*
> We of course could make do with only half the reflector and the LED firing up into this for low beam, so no lost light.


The setup would be similar to one of the images that Riken posted earlier, but isn't there smaller aspheric lenses that can be used? (Think I've seen some on DX.) and then combine it with half a reflector? Also, the finish of the reflector would probably make a difference...OP would smooth out the beam and give more uniform light I think.



> Originally Posted by *mfj197*
> Are you tempted to try and make a light out of it?


Yes, but the original idea was to copy the principle and make it smaller (like mentioned above)...for my use I would only need one XM-L or similar LED. Been busy with other projects so have not had proper time to play with it yet.



> Originally Posted by *mfj197*
> Having said all that, there is probably a point where the increased weight and complexity of a mechanism to harness all that light outweighs the additional weight of just adding more LEDs and cells in the knowledge that half of the emitted light is being wasted.


Good point, but if you could get it right with a simple setup it could be worth it. Are you aiming at just a low beam, or a "bi-xenon"-like setup?

Oh I forgot to mention that when I was playing with the mag and front aspheric part, I picked up that the shield is placed at the aspheric's focal point.


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## mfj197 (Jan 28, 2011)

Rekkie said:


> The setup would be similar to one of the images that Riken posted earlier, but isn't there smaller aspheric lenses that can be used? (Think I've seen some on DX.) and then combine it with half a reflector? Also, the finish of the reflector would probably make a difference...OP would smooth out the beam and give more uniform light I think.


Yes, there are many aspherics out there which could make the front of the light design smaller. The smaller the aspheric the wider the resultant beam. However there's still the issue of needing to house the reflector and have a tube long enough to hold the whole thing together.

I'm looking at just a low beam setup, as really that's all that's needed to illuminate (the road ahead). I have been rather tempted to get a light from this website to modify, but I'd still be very concerned about the weight and size of even the smallest of these. The low beam would be effected by having an LED firing upwards into only half the rear reflector, rather than needing a cutoff shield.

Mind you, sounds like brad72 might be leading the way on large (but effective) lights at the moment!  Look forward to seeing the photos.


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## mfj197 (Jan 28, 2011)

As a result of the projector headlight chat in the last few posts I've sourced a very small projector headlight, 38mm lens, 100mm length, 195g all in. I'll cut the bottom half of the reflector off and mount an LED on a heatsink, so weight will probably be slightly higher but not by much. I had been planning two identical lights but if this one is quite a size and weight I may just run one. The next question therefore is ... XM-L, SST-50 or even SST-90!?


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## Rekkie (May 26, 2011)

38mm lens sound a lot better! and 195g wouldn't bother me. I for one would go for the XM-L...cheaper, not as power hungry so smaller battery pack needed = weight saved...also never used a SST due to its price tag.


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## mfj197 (Jan 28, 2011)

I know, but with one XM-L I think I'd feel vastly inferior to you guys with your triples! 

I think you're probably right. The projector headlight is designed to use an H1 halogen bulb which is 1,550 emitter lumens, and the dipped beam version immediately loses half of that so 775-odd. I'd have 1,000 lumens of well-controlled dipped beam light with a single XM-L. I should be happy with that I guess!


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## Rekkie (May 26, 2011)

Correct me if I'm wrong...but I think you will probable end up with around 900 lumen out the front due to lens efficiency...but still, that would be 900 well controlled lumens.


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## mfj197 (Jan 28, 2011)

You'd be quite right - sorry, I was talking emitter lumens only in the comparison with the H1 halogen 55W bulb. There will be losses from both the reflector and the lens - I don't know if the losses from an aspheric are any different from a normal window lens on a flashlight? I guess it depends on quality / imperfections in the glass?


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## mfj197 (Jan 28, 2011)

Looks a promising start ...


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## Rekkie (May 26, 2011)

Looking good! Looks like it's a BMW motorbike fog light?? I just remembered they're quite small. I'd be more than happy with that size. All the best with the modd!!


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## Bikelight (Jul 11, 2011)

mfj197 said:


> Latest (zany) thought - LED mounted in the traditional orientation but the reflector cut and the top half moved aft, so the bottom works using Method A and the top using Method B, as in the following picture. This might mean I can use the smaller smooth reflectors that you guys are using elsewhere, rather than the 50mm monsters I currently have!


 The reflector from the torch is not good for you, you should try the car headlight optical will be batter.
The light distrubtion is very important for your design. you may use "tracepro" to trace the ray.:eekster::eekster:

Hope it will help you!!

Sorry the hyper link function is not available"To be able to post links or images your post count must be 10 or greater" :madman::madman:


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## mfj197 (Jan 28, 2011)

Bikelight said:


> The light distrubtion is very important for your design. you may use "tracepro" to trace the ray.:eekster::eekster:


Good call, thanks for that. Have you tried the Tracepro software yourself? It looks good and has a 30 day free trial as well which should be long enough for trying out most permutations.

Rekkie, I think I know the foglights you refer to. The light I'll try and mod is a small main-beam aftermarket headlight for motorbike mods so hopefully it should project reasonably well.

Edit: Even nicer, I see that Cree has Tracepro data files to model the XM-L (and I assume other emitters as well).


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## Bikelight (Jul 11, 2011)

mfj197 said:


> Good call, thanks for that. Have you tried the Tracepro software yourself? It looks good and has a 30 day free trial as well which should be long enough for trying out most permutations.


 Yes, but it was 1 year ago!! But I think I still can recall some tip if you need help!!

Most of vechile light design concept was come from car headlight, you also can visit some car headlight company like "Automative Lighting", "Hella", "Stanley Electronic"... to see what they do!! In bicycle light, only few company had the optical skill to design the bicylce light, most of people concern is how many lumens from the led, not the energy on the road...

Anyhow, if you need anything, feel free to let me know!!


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## Rekkie (May 26, 2011)

Any update / progress?


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## yetibetty (Dec 24, 2007)

These look interesting http://www.ledil.com/sites/default/files/Documents/Technical/Brochure/Strada-F-series.pdf

I am tempted to try and do a road light as they have put the tain fares up again in the UK and I don't drive.

Tried riding on the road with my DIY off road lights and keep getting flashed.......and they are on low.


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## mfj197 (Jan 28, 2011)

I noticed the Ledil Strada F series - they could certainly be interesting. I haven't seen any beamshots yet but it might be worth getting a couple to try out. I'm not sure if they'll project far enough though?

From my part XM-Ls arrived yesterday and sections of alu square tubing have already been procured. Have cateye spacers and other assorted bits too. I've cut up another reflector to compare and I think my wife might be getting a bit tired of me standing at the back door late at night shining lights across the garden! I'm doing a reflector-based design first before thinking about a projector setup.

The one issue is the beam is so sensitive to LED placement that I might need some way to ensure it can be moved to get an optimal beam pattern before fixing it permanently. I think trial and error will need to be used rather than trying to measure!

Michael


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## Rekkie (May 26, 2011)

Found this old thread up on CPF to maybe have a look at (have not read through it all myself) : Let's design a road front light beam

And found this light Supernova Lighting Systems - E3 E-Bike ...don't know how the lens(s) or ... works though.


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## unterhausen (Sep 28, 2008)

I have an E3 asymmetric, and I like the beam. The hole in the front is a bit of a mystery to me, although it seems clear that the reflector is prismatic and does all the shaping of the beam.


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## mfj197 (Jan 28, 2011)

The E3 beam almost looks like it is two images of the die, one smaller and more focussed (i.e. using a larger aspheric or reflector) and one larger aimed down slightly giving the wider spread.

There is a lot of good information in the thread Rekkie linked to. Some of it gets fairly technical and it's quite a read, but there are some great ideas.

I was out last night comparing beams as I was thinking of having a light (well, two) comprising a road-friendly aluminium Mag reflector cut in half as above with one XM-L, and a second XM-L with Laura as a main beam. However the Mag reflector was putting more light on the ground at distance than the Laura could. I don't think there's a point in me putting a main beam on a light if I get better illumination from the dipped beam!

Sorry for the delay in this, life's been a bit busy over the summer but I've now got most of the bits to start construction. The days drawing in is also a bit of an incentive!


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## mfj197 (Jan 28, 2011)

*Beamshots!*

I've ended up using a reflector from my wife's old halogen light cut in half. It's mounted using method A, i.e. the LED firing down into the reflector. I'll start a build thread when I've finished the lights, but as input to this thread here's a couple of beamshots in my back garden. They are using a single XM-L U2 bin, driven at 2.8 amps, with photographs taken at (the equivalent of) the MTBR settings.

First the control shot:


Secondly with a Regina reflector:


Lastly the cut-off reflector:


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## Rekkie (May 26, 2011)

Can see from the beamshot there is more light on the ground with the cut reflector than with the Regina...PERFECT!!
Just one Q: what's the distance from the light to the far wall? in the picture?

GREAT JOB!! :thumbsup::thumbsup:

looking forward to the build thread.


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## BrianMc (Jan 5, 2010)

mfj197 said:


> I was out last night comparing beams ... the Mag reflector was putting more light on the ground at distance than the Laura could. I don't think there's a point in me putting a main beam on a light if I get better illumination from the dipped beam!
> 
> Sorry for the delay in this, life's been a bit busy over the summer but I've now got most of the bits to start construction. The days drawing in is also a bit of an incentive!


Nice beam. It only took me 6 months to shoot a decent riding with the lights video, so I am not complaining.

WRT overshooting the mark: I had much the same issue when I cranked the double XM-L's to 2.8 A here. The helmet light adds nothing at 0.5 A except on corners or to look outside the beam zone. At 1 A, it is good looking around corners and reinforces the lead part of the beam some. Backing the headlights down to 2 A provided ample light close and the Helmet light at 1 A adds nicely to extend the beam more obviously. Now I will need to bag each light in turn to compare the beams and do beam shots, with and without the hoods. So now I want to replace the XP-E R3 with an XP-G de-domed, and use an XM-L for the closer larger die in of that triple stacked die beam and try it at 1.2 and 1.5 A. Seventeen Watts @ 1.5 A will need some fins or a bigger housing (7 square inches barely handle 11 Watts at 65 F).

The old MR11 halogen bulbs went AWOL but I found them. I will have some LED's coming so if I can figure out a safe way to cut them, I will mock up a variation on your idea for a beam test.

BrianMc


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## mfj197 (Jan 28, 2011)

Rekkie said:


> Can see from the beamshot there is more light on the ground with the cut reflector than with the Regina...PERFECT!!
> Just one Q: what's the distance from the light to the far wall? in the picture?
> 
> GREAT JOB!! :thumbsup::thumbsup:
> ...


Thanks Rekkie. The distance from the light to the fence at the end of the garden is about 17 metres, or 55 feet.


BrianMc said:


> Nice beam ... WRT overshooting the mark: I had much the same issue when I cranked the double XM-L's to 2.8 A here. The helmet light adds nothing at 0.5 A except on corners or to look outside the beam zone...


Thanks Brian, and good to see your videos. My comments were really an observation that it wasn't worth trying to build and integrate a high-beam if there was more throw out of the dipped beam. The light on the ground at distance is greater with the dipped beam than with a Regina (or a Laura). I have a head-mounted flashlight blinking for attention-grabbing but that is really only used for being seen, not for seeing.


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## BrianMc (Jan 5, 2010)

mfj197 said:


> My comments were really an observation that it wasn't worth trying to build and integrate a high-beam if there was more throw out of the dipped beam. The light on the ground at distance is greater with the dipped beam than with a Regina (or a Laura). I have a head-mounted flashlight blinking for attention-grabbing but that is really only used for being seen, not for seeing.


Glad someone liked the video. Yeah, I got your comment on the throw issue. My helmet light does extend my throw with the three XP-G headlight on the errand bike, and it did with the XM-L lights at 1.4 A (all I could coax out of the old pack). I wasn't expecting these big XL-L dice, even with 35 mm optics, to do so well. punching a hole in the dark that far out.

The helmet light works great on flash mode in the day and it is a real attention grabber for drivers who are not noticing me and I look at them. Works in day light, too. The movement of the beam may be picked up by the sub-concious. A high helmet ligt and low head light are like nothing else on the road. Throw in the side output and tail lights showing up at a fair distance and the 'what the heck is that?' factor to break through cell-phone call inattentiveness is high. Maybe wheel lights on the front wheel to scream 'Bike', and at that point, I have done all that I can reasonably do to be seen.

BrianMc


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## mfj197 (Jan 28, 2011)

For completeness (and for googlers who land on this thread), here's a link to a build thread based upon these reflectors.


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## savvas (Mar 21, 2011)

Philips appear to have a new, more compact version of their battery light now available. Bike24 have it - maybe others as well. It has an external battery and what looks like the shorter housing of the dynamo version. Only one LED it seems. It's fairly cheap so may be a good host for DIY???
Savvas.


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## HakanC (May 12, 2007)

Is it this 40 Lux light you mean
Bike24 - Philips LED SafeRide Battery Front Light Set 40 Lux black

I my opinion 40 Lux is too little.
But hopefully Philips will upgrade the 80 Lux version (100 - 120 Lux would be fantastic!) with an external battery pack.
Here is an ongoing review of the dynamo-verison of the 40 Lux Philips-light
Bicycle lighting, in particular LED headlamps (headlights) with cutoff, and (hub) dynamos


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## mfj197 (Jan 28, 2011)

What's interesting there is the reflector design. The 40 lux versions, both dynamo and battery, are single LED with a very different approach to reflector design to the twin LED versions. Bike24's picture of the 40 lux dynamo version is incorrect and shows the twin LED 60 lux version, with twin LEDs firing down into the reflector. Here's a better page for the 40 lux dynamo, and the image below clearly shows the LED mounted at the bottom firing up into the reflector:









Here's an even clearer picture (40 lux battery version from this site):








Here's Philips' Saferide Facebook page which has some pictures of all of the lights.
What this means is that the twin LED versions are using method A from the first post, firing down into the reflector from on / behind the focal point of the parabola, whereas the single LED versions are using method B, firing up into the reflector from in front of the focal point of the parabola. The pictures in post 22 show the difference in output. Incidentally method B is that used by standard halogen car headlamps with twin filament bulbs.

In trialling it outside I found that method A produced longer throw and provided light up to the front wheel. Method B produced a nice cutoff, good midrange illumination and you could use a smaller reflector as the LED is that little bit further away from the focal point. However it didn't throw as well, provided no light at all by the front wheel and was also a little bit brighter to oncoming traffic as they can directly see the LED (spill light going up rather than down).

I wonder why Philips chose to use two completely different approaches for the 1 LED versus 2 LED lights?


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## savvas (Mar 21, 2011)

HakanC said:


> Is it this 40 Lux light you mean
> Bike24 - Philips LED SafeRide Battery Front Light Set 40 Lux black
> 
> Yep - that's it. And thanks to mfj197 as I had no idea of the reflector differences pointed out. I doubt many thinking of purchasing these lights online would have picked those up! I have not really kept up with Philips lights so I had not realised there were multiple models available. I knew there was a battery light and had read the review site up to a point, but when I bought my dynamo light nearly 2 years ago (from Bike24 or maybe RoseVersand) there were only 2 models available - a battery and a dynamo. Luckily I got what now appears to be sold as the 2-led, 60 lux dynamo model. I find it a very useful light for back street commuting although I do think the standlight could be a bit stronger. I have been jealous of the power of the 80lux battery model and have wondered if mine could be simply upgraded using xpgs or xmls. I think Philips have the basis of a premium light here - maybe they need ktronik 'on staff'.
> ...


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## HakanC (May 12, 2007)

Thanks mfj197
Very good posting.


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