So how many of us have flown along close to cloudbase under a cloud street, and suddenly seen another glider pass us on the opposite heading?

It's obviously hard to see a glider that is coming straight at you.

So what about a narrow beam LED strobe aligned with the glide path vector... would the other glider see it? Would it be legal? Could you shine it through the canopy with a baffle to block internal reflections?

Has anyone done this?

I once saw another glider coming towards me on a ridge with wing tip strobes. It really got my attention and in plenty of time. So I kinda think that this would work.