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Rayleigh Interferometer
Collimated coherent light passing through two tubes with different refraction index gases, then an imaging lens creates the interferogram.

The Rayleigh interferometer employs two beams of light from a single source, and determines the difference in optical path length between the two paths using interference between the two beams when they are recombined following traversal of the paths. An example is shown in the figure.[1] Light from a source (top) is collimated by a lens and split into two beams using slits. The beams are sent through two different paths and pass through compensating plates. They are brought to a focus by a second lens (bottom) where an interference pattern is observed to determine the optical path difference in terms of wavelengths of the light.

Advantages and disadvantagesEdit

The advantage of the Rayleigh interferometer is its simple construction. Its drawbacks are (i) it requires a point or line source of light for good fringe visibility, and (ii) the fringes must be viewed with high magnification.[2]

See alsoEdit



  • Busch, Kenneth W.; Busch, Marianna A. (1990). "§6.6.5 The Rayleigh interferometer". Multielement detection systems for spectrochemical analysis, Volume 107. Wiley-Interscience. p. 231. ISBN 0-471-81974-3.
  • Hariharan, P. (2007). "§3.3: The Rayleigh interferometer". Basics of interferometry (2nd ed.). Academic Press. p. 15. ISBN 0123735890.