A gravitational wave alternately stretches one arm of a Michelson interferometer while squeezing the other, shifting the interference pattern reaching the photodetector.
h(t) = A · sin(2π f t)
ΔL_x = L(1 + h/2), ΔL_y = L(1 - h/2)
I_det ∝ 1 - cos(4π ΔL/λ)
- Wave amplitude — the dimensionless strain h (scaled up here for visibility) set by the source's mass and distance.
- Wave frequency — orbital chirp frequency of the merging pair as it spirals inward.
- Laser power — beam intensity in each arm; higher power raises the photodetector signal-to-noise.
- Source distance — farther sources produce a weaker strain at the detector, mimicked here as an amplitude attenuation.
LIGO/Virgo-style observatories use kilometre-scale arms and can resolve strains smaller than 10⁻²¹ — a fraction of a proton's width.