🌈 Diffraction Grating

📖 The Physics

A diffraction grating is a slide ruled with thousands of fine, equally spaced slits. Light from all of them interferes, and it only adds up brightly at a few precise angles — the orders.

The more slits take part, the sharper each bright line becomes, because a stray angle that's even slightly off gets cancelled by some distant slit.

Increase the number of slits N and watch the fuzzy peaks snap into thin, bright lines — that precision is why gratings measure wavelengths so well. A finer grating (more lines/mm) spreads the orders further apart, and each wavelength lands at its own angle (a spectrum).