That harsh white flash is not stronger than the Milky Way; it is smarter. In the dark-adapted human eye, rods saturate on contrast, not on total power across the sky, so engineers design for a single, knife-edged signal that hijacks that physiology.
At the core sits a Fresnel lens, a stacked ring structure that bends light with minimal absorption and sends it into a narrow divergence angle, trading wasted lumens for intense candela in one direction. Instead of spraying photons, the optical train squeezes them into a rotating sheet, so for a brief instant the sailor receives a concentrated pulse that dwarfs any single star on the retina.
Equally deliberate is the timing. A coded flash pattern, set by the rotation period and shutter geometry, gives the brain a repeatable signature, which signal detection theory says is far easier to pick out than a static glow against stellar clutter. Add spectral tuning toward wavelengths where rods are most sensitive and strict shielding that kills stray spill light near the horizon, and the result is a low-tech machine that wins the contrast contest against the galaxy by exploiting biology, not brute power.
