Some harbour/river entrances have a sectored light. White if you're sailing in safe water, red if you're to the left of it, green if you're to the right. Makes a fantastic navigation aid for the entrance and I'll take a setup like that over a plotter for pilotage any day.
https://en.wikipedia.org/wiki/Precision_approach_path_indica...
Flashing to indicate how much of a correction needs to be made and turning yellow once on center line.
Incidentally I couldn't find much information on this "Long range laser lineup" outside of DCS where I've heard of this first, a bit odd considering the other landing system for glide slope is fairly well documented.
Perhaps laser is also good to reduce the visible signature of the ship, the fewer lights the better. Or maybe it's just brighter for the pilots.
> maybe that's legacy now
No as far as I'm aware it continues to be a thing, to assist in keeping on glidepath.
The lineup system is for aligning to center line (horizontally relative to carrier's deck) from a distance. I did find it odd that there is barely any mention of it outside some internet forums, the closest to an authoritative source I found was this https://www.cnatra.navy.mil/local/docs/pat-pubs/P-816.pdf (see Page 24)