the LD in the middle in the last pic is the red emitter from the bluray writer sled. the one to its right is the well-known long die open can, the one to its left is a normal closed can. it seems that its die is probably as long as the open can one. the only diode i know of in a case like that is Mitsubishi's ML101J27 rated for 130mW CW max.
i didnt use any atmosphere additives. but it doesnt look like that either. the camera makes out the beam in a well-lit room easily, whereas my eyes dont : . all pics were taken w/o flash and the camera automatically increased exposure time accordingly
visibility is in the eye of the beholder... i see it as an eerie pale gray line with horrible divergence(due to my eyes' inability to focus it correctly), which in fact it isnt.
I'd use a green for sky pointing. Bluray is good for fluorescing things, it produces a brilliant blue spot on white paper and a meager barely visible purplish spot on black and non-fluorescent surfaces.