Could also just let in like 1e-51% of the light and now it becomes a game of who has sufficient technology to detect a ship-sized darker spot. I guess you can

Could also just let in like 1e-51% of the light and now it becomes a game of who has sufficient technology to detect a ship-sized darker spot. I guess you can get a similar effect by having a garage door beam set-up where you flash a bright light and try to detect a cloaked ship passing through the "beam" by seeing them take too long to re-transmit a photon.