For the last 2 years, I have been running a Luxeon III with a Taskled 700ma CC board, through a narrow beam fraen lens, supplied by a hub dynamo (6V 500mA) and 1N5821 bridge rectifier circuit w/smoothing cap. The system has been very reliable, but the light output to the road is, at best, adequate.
I'm pretty much happy with the dynamo as the power supply, for various reasons of convenience, reliability etc, so I need to look at other ways to improve the perfomance for my application. My night time riding is all on paved roads, mostly in rural unlit areas, passing through some towns.
One idea I have is to not rectify the output, instead running each A.C halfwave through a seperate L.E.D, for basically zero unnecessary losses. Also these could be some more modern K2 L.E.Ds.
The other area I have looked at is the optics. Although the beam is supposedly 10 degrees, there is a large amount of spill noticeable, and to get the spot in a useful, optimal place results in a large amount of light wasted, as the light pointing above this point is not concentrated enough, and is pointing too far away to be of any practical use.
Commercially available lamps designed for road commuting use address this issue by producing a very tight beam of a certain nature. This has the lions share of the produced light directed forwards towards a point just below the horizon (i.e. down on to the road, in the distance), and tapering off in a downwards direction, i.e. toward the source on the road in front. Any light above this point is sharply attenuated as it serves no purpose and is better off used where it is, as is any side spill. In this way they make the best use of the limited light available.
Commercially produced L.E.D units of this type are now slowly becoming available, but aside from the fact I'd rather build my own, there are other disadvantages:
A They are somewhat pricey, although well designed.
B They are not upgradeable, making them useful only for a short time until they are effectively obselete and underpowered.
So, basically my question is: Does anyone know where optics like these can be found. The only ones I've ever seen were spot, oval or a wide, flat type of beam.