A two-aperture mask illuminates a position-sensitive screen. The screen accumulates discrete detection marks drawn from a finite-width double-slit distribution.
• Coherent illumination, two finite apertures, an overlapping wavefront guide, a position detector and accumulated position counts. • Controls for wavelength (nm), slit center separation (µm), each slit width (µm), mask-to-screen distance (m), path coherence and detections per second. • Four tabs: Quantum bench, Probabilities & measurements, Experiments (with built-in model checks), and Learn & assess.
I(y) ∝ sinc²(πa sinθ/λ)[1 + V cos(2πd sinθ/λ)]/2, with sinθ = y/√(y²+L²). Paraxial fringe spacing ≈ λL/d and the envelope zero ≈ λL/a. The distribution is normalized over the displayed ±30 mm screen before sampling.
This is a Fraunhofer scalar two-slit model with equal illumination and phenomenological coherence. It has no near-field propagation, finite source bandwidth or detector noise; the geometry is compressed and the wavefront rings are illustrative. Setting coherence to zero removes the fringes, not the single-slit diffraction.
No. Each finite aperture still contributes a diffraction envelope; setting path coherence to zero removes the fringes but leaves the smooth envelope.
No. Only detection positions are sampled; no intermediate path is measured.
Smaller separation gives larger fringe spacing (the "Wide fringe spacing" preset), following a paraxial spacing of about λL/d.
The diffraction envelope broadens, revealing more fringes (the "Narrow apertures" preset); the envelope zero is at about λL/a.