Originally Posted by
noglider
Take a look at a B&M or similar European headlight. [...] The B&M has its LED on top, pointing down, and the reflector turns it forward. There are many subtle curves to achieve the beam shape, and the result is that it is brightest at the top. This way, intensity does not diminish along the ground as you get farther from the headlight. It's not just a cutoff.
And maybe I'm giving more credit than necessary, but I can't help being impressed.
That is the best way to control the beam shape with LEDs. Outbound and Supernova use the same approach, Lezyne does it as well for their StVZO lights, and Lupine as well for their new light. The other way are one or two aspherical lenses, used in the case of the Lupine SL(F) (or a combination of a reflector and a projector lens). All modern LED lights in cars use the same principles: either pure projector lenses, or a combination of LEDs shining indirectly on a reflector with a projector lens at the front, or simply downward facing LEDs.
The layered light with the highest intensity is the
key for a good bike light and you don't give too much credit!