Iridescence

The colours of soap bubbles, oil on a puddle, and Newton's rings — computed, not painted. Light reflecting off the two faces of a thin film interferes; the path difference 2nt cosθ′ cancels some wavelengths and reinforces others. Each pixel's colour is its reflected spectrum integrated against the CIE 1931 observer.

Mode

Light

Wavelength λ 589 nm

Lens

Radius of curvature R 8.0 m

Tilt 0.0

Animation

Drain / drift

Spectrum at cursor

Hover the film to read its thickness & reflected spectrum.

Feat — match the colour

In white light, hover the film to find the spot whose colour matches this swatch.

Skin

Newton's rings: a lens on glass — the air gap t = r²/2R; dark rings at 2t = mλ, a dark centre. Soap film drains to a wedge: a black top band then descending colours. Oil slick: an oil film on water swirls. Hover anywhere to read the physics.