N-slit interferometer

Feynman[3] described thought experiments the explored two-slit quantum interference of electrons, using Dirac's notation.

[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] The N-slit laser interferometer, introduced by Duarte,[5][6][10] uses prismatic beam expansion to illuminate a transmission grating, or N-slit array, and a photoelectric detector array (such as a CCD or CMOS) at the interference plane to register the interferometric signal.

This is due to the fact that propagating N-slit interferograms suffer catastrophic collapse from interception attempts using macroscopic optical methods such as beam splitting.

[9] N-slit interferometers, using large intra interferometric distances, are detectors of clear air turbulence.

[6][10][14] In particular, the one dimensionally expanded laser beam (with a cross section 25-50 mm wide by 10-25 μm high) was used to illuminate imaging surfaces (such as silver-halide films) to measure the microscopic density of the illuminated surface.

Top view schematics of the N-slit interferometer: TBE is a telescopic beam expander, MPBE is a multiple-prism beam expander. The N-slit array is at j (with the slits perpendicular to the beam expansion) and the interferometric plane is at x where the digital detector is positioned. [ 6 ] [ 7 ] [ 8 ] [ 9 ] The intra interferometric distance D has been reported to be as large as 527 m. Note : N -slit interferometers include three-slit interferometers (or triple-slit interferometers), four-slit interferometers, etc. [ 7 ] [ 8 ]
Interferogram for N = 3 slits with diffraction pattern superimposed on the right outer wing. This particular interferogram corresponds to the interferometric character "b". [ 9 ]
The diffraction pattern over the interferogram shown above, corresponding to N = 3 slits, was generated using a single spider silk fiber with a diameter of about 25 μm. [ 9 ]