The N-slit interferometer is an extension of the double-slit interferometer also known as Young's double-slit interferometer. One of the first known uses of N-slit arrays in optics was illustrated by Newton.[1] In the first part of the twentieth century, Michelson[2] described various cases of N-slit diffraction.
Feynman[3] described thought experiments the explored two-slit quantum interference of electrons, using Dirac's notation.[4] This approach was extended to N-slit interferometers, by Duarte and colleagues in 1989,[5] using narrow-linewidth laser illumination, that is, illumination by indistinguishable photons. The first application of the N-slit interferometer was the generation and measurement of complex interference patterns.[5][6] These interferograms are accurately reproduced, or predicted, by the N-slit interferometric equation for either even (N = 2, 4, 6,...), or odd (N = 3, 5, 7,...), numbers of slits.[6]