Time0

Wavelength S1–

Frequency S1–

Frame rate–

Probe Source Screen

Inspector Hover over the tank Shows refractive index, amplitude and local wavelength.

Drag sources and probe with the Move tool · Shift+drag moves the optical element · paint walls and media with the other tools

Wave Lab

A real-time 2D wave-equation solver (finite differences, 400×300 cells) with absorbing sponge boundaries. Build slits, lenses, prisms and waveguides, then watch diffraction, refraction and interference emerge from one equation.

Simulation speed 3.0 steps/frame Burst mode (sources emit a short wave packet when fired)

Presets

Mouse tools

Brush radius 5 Painted refractive index n 1.50

Sources

Type Active

Frequency 0.030 Amplitude 0.60 Phase 0°

Length 200 Orientation / beam tilt 0°

Source speed 0.00 c Heading 0°

Optical element barrier / medium

Element Position x 130 Position y 150 A 8 B 48 C 6 Refractive index n 1.50

Display

Colour gain 1.0×

Screen Probe λ ruler Show sponge

Screen position x 350

Probe drag the probe marker

Screen intensity time-averaged ⟨u²⟩ at the screen

simulationFraunhofer theory

Things to try

Double slit: fringe spacing is Δy ≈ λL/d. Widen d and the fringes squeeze together.
Snell / TIR: paint a high-n region; waves bend toward the normal and, going from high to low n at a steep angle, reflect totally.
Doppler: speed up the moving source past 1.0 c to see a Mach cone.
Paint your own walls and media, then drag the probe to measure the local wavelength with the FFT.

Units: 1 cell = 0.5 mm, 1 step = 1 time unit, background wave speed c = 0.5 cell/step. Frequencies in cycles/step.