What good is a stealth aircraft if as soon as it starts firing tracers any AA gunner or other AA unit can follow the tracer track back to the aircraft and shoot it down? Well, no good at all.
Back in the days when we planned to arm the steath aircraft this was a real concern.
One answer was the PASSIVE TRACER.
An ACTIVE TRACER is burning or emitting something which can be followed.
A PASSIVE TRACER emits nothing but rather is trackable by other means.
These NORTHRUP experimentals trace by reflecting light from a laser mounted on the aircraft.
A variety of mirrors and prisms were tried. Numerous types of lasers were also tried.
“Super John” Morris “The cannon king” - Springfield Arsenal demonstrates a top secret US NAVY experimental propulsion experiment. He designed guns for the USN. Now retired. (possible joke)