Single-slit diffraction minima
An aperture's finite width selects dark far-field directions.
Key knowledge
For uniform monochromatic illumination of a single slit, Fraunhofer diffraction minima occur at a sin θ = mλ for nonzero integers m within the allowed angular range.
Values and equations
a sin θ = mλ, m = ±1,±2,…
- a
- Slit width m
- λ
- Light wavelength in the propagation medium m
- θ
- Angle from the forward direction rad
- m
- Nonzero integer diffraction order
Conditions and scope
- Far-field approximation, or a lens forming the far-field pattern; slit width a > 0 and normal plane-wave illumination with uniform phase and amplitude across the slit.
- m = 0 is the central maximum, not a dark fringe; finite near-field patterns need another model.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Section 4.1: paired-wave cancellation and nonzero-order minima.
2026-10-10 · Uniform single-slit far-field minima only; multi-aperture or vector diffraction excluded.
Entry details
Permanent link to this entry ↗- Record identity
- physics-diffraction
- Revision
- university-reference.1
- Structured reference record
- University reference · University core expansion