Michelson Interferometer

The two arm lengths are one-way distances in metres. Their signed round-trip difference is δ₀=2(L₁−L₂). Moving M₂ by d adds 2d to arm 2, so δ=δ₀−2d and fringe shift Δm=−2d/λ. The separate nanometre offset avoids losing tiny moves when adding them to a metre-scale arm.

This is an explicit coherent plane-wave screen model. Mirror tilt α gives a transverse phase gradient sin(2α)/λ. At detector position x: phase=2π[δ/λ+x sin(2α)/λ], normalized intensity=[1+V cos(phase+port·π)]/2. The chosen output port fixes the constant phase convention; its complement is dark when the first is bright. At zero tilt the field is spatially uniform. Circular fringes require a different wavefront model and are not fabricated here.

The display averages intensity over each pixel interval. Unresolved fine fringes lose contrast and may show sampling patterns, not resolved detail. The diagram is schematic, not a scale drawing. Visibility V is a phenomenological contrast parameter; intensity is normalized, not absolute optical power.

λ/2 moves M₂ by one fringe from its current position. The displacement field defines a static offset; oscillation adds A sin(2πft). Amplitude and frequency are separate. Pause/resume preserves phase; edits stop motion, Reset sets offset and time to zero while retaining other inputs. Hiding the tool pauses it. Large amplitudes/rates may be temporally undersampled; slow them to follow fringes. Zero amplitude or rate is static. Ideal monochromatic coherent beams in air, no circular/diffraction pattern, spectral coherence or absolute detector calibration. Raw input text, including unfinished entries, stays in this browser. Motion, time and detector samples are not saved. The profile below the pattern uses exactly the same pixel-averaged intensities.