The purpose of this page is to build a Mach-Zehnder Interferometer (MZI).

Laser beam


  • Laser He-Ne 16 mW.
  • mounted on a XY stage to center the beam.

Custom beam expander

 Cage system


Lens 1, version 1:

Lens 1, version 2 (90$):

Lens 1, version 3 (130$):

Lens 2:


About the choice of the pinhole:

Explanations from Newport or thorlabs

\[D_o = F \lambda/a\]

where F = focal, lambda = wavelength, a = initial diameter). Here, we have F = 18.5mm; lambda = 632 nm; a = 1mm gives 12µm. Thorlabs recommend 30% higher. So, 15 µm.


2 mirrors:

First beam splitter (where the beam comes out):

Second beam splitter (where the beam comes in):



Mach-Zehnder Interferometer

Mach-Zehnder Interferometer

Mirrors and beam splitters

Mirrors and beam splitters

First lens and spatial filter

First lens and spatial filter


  • We thank Pierre Colinet for suggesting the MZI.
  • We thank Irène Wang and Joseph Gallagher for helping us to make the best choice for the various optical components presented here.
  • This page has been realized by François Ingremeau and François Boulogne.