multislit

Multislit refers to an arrangement of more than two slits used to diffract and interfere waves, typically light or electrons. It generalizes the classic double-slit experiment and forms the basis of diffraction gratings used in spectroscopy and optical instrumentation. A multislit setup consists of N identical slits of width a, spaced by center-to-center distance d.

The angular intensity pattern I(θ) for monochromatic light of wavelength λ is given, in the common approximation neglecting slit width, by I(θ) ∝ [sin(Nβ/2)/sin(β/2)]^2 with β = (2π d sin θ)/λ. When slit width a is non-negligible, the pattern includes an envelope factor (sin(π a sin θ/λ)/(π a sin θ/λ))^2 multiplying the N-slit term. Principal maxima occur near d sin θ = m λ, where m is an integer. Increasing N narrows the principal maxima and increases peak intensities, enhancing angular resolution, while the overall envelope is governed by the single-slit diffraction term.

In practice, panels of equally spaced slits act as diffraction gratings that separate light into spectral components. Multislit interference is also studied with particles such as electrons, neutrons, or molecules, illustrating wave-particle duality.

Applications include spectral analysis, optical metrology, calibration of instruments, and experiments in fundamental quantum mechanics. Variants include arrays produced by lithography or micro-fabrication, and flexible fiber-optic or microelectromechanical implementations.