Single-Slit Diffraction Calculator

About this calculator

When light passes through a narrow single slit, it spreads out and produces a pattern of bright and dark fringes on a screen rather than a sharp shadow — a direct demonstration of light's wave nature. The dark fringes (diffraction minima) occur where a sin θ = mλ, with a the slit width, λ the wavelength, θ the angle from the central axis, and m the integer order (1, 2, 3...); the position on the screen follows from θ and the slit-to-screen distance.

Physics students verify this relationship in the classic single-slit lab, while optical engineers and spectroscopists use it to predict how narrow apertures, laser beams, and spectrometer slits will spread light — critical when designing instruments that need to resolve fine spectral or spatial detail.