I have one of those new-fangled eBarf bright lights (600LM) but I tend to shine it down about 8-10m (8-10yd) in front of me. They all suffer from the same problem, their beam is very focused and as such, if it were pointed up, it would dazzle someone. I've been thinking about how I might devise a diffuser to (1) reduce the intensity of the light when viewed straight on (an angled down light is still going to be in someone's eyes when cresting a hill) and (2) diffuse the light across the road more. A small dot (hole puncher size) of cello tape might help with my first goal but not my second.
I had thought of scratching up the front glass (may not be glass) but, if it failed, I've damaged my light. If anyone has any other ideas, that'd be great!!