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White Light Interferometers

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Definition: interferometers using broadband light inputs

German: Wei├člichtinterferometer

Categories: optical metrology, photonic devices

How to cite the article; suggest additional literature

A white light interferometer, used e.g. in the context of low-coherence interferometry, is an interferometer, typically a Michelson interferometer, which works with a white light source, i.e. with a light source with broad optical bandwidth. The light source does not necessarily operate in the visible spectral range, really generating white light. Its temporal coherence has to be fairly small, whereas a high spatial coherence is normally needed. The high spatial coherence combined with a broad bandwidth can most easily be obtained by launching light from a bulb into a single-mode fiber, but this leads to a very small launched power. The radiance (brightness) can be increased by many orders of magnitude by using a superluminescent source such as a superluminescent diode. In some cases, wavelength-swept tunable lasers are used.

The detector in a white light interferometer can either be a photodetector which integrates contributions of different wavelengths and records the signal in the time domain, or a spectrometer (spectral interferometry).

Application of White Light Interferometry

White light interferometry is used for different purposes. The main applications are:


The RP Photonics Buyer's Guide contains 6 suppliers for white light interferometers. Among them:


[1]K. Naganuma et al., “Group-delay measurement using the Fourier transform of an interferometric cross correlation generated by white light”, Opt. Lett. 15 (7), 393 (1990)
[2]M. Beck and I. A. Walmsley, “Measurement of group delay with high temporal and spectral resolution”, Opt. Lett. 15 (9), 492 (1990)
[3]A. P. Kovacs et al., “Group-delay measurement on laser mirrors by spectrally resolved white-light interferometry”, Opt. Lett. 20 (7), 788 (1995)
[4]S. Diddams and J.-C. Diels, “Dispersion measurements with white-light interferometry”, J. Opt. Soc. Am. B 13 (6), 1120 (1996)
[5]C. Dorrer et al., “Experimental implementation of Fourier-transform spectral interferometry and its application to the study of spectrometers”, Appl. Phys. B 70, S99 (2000)
[6]Q. Ye et al., “Dispersion measurement of tapered air–silica microstructure fiber by white-light interferometry”, Appl. Opt. 41 (22), 4467 (2002)
[7]A. Gosteva et al., “Noise-related resolution limit of dispersion measurements with white-light interferometers”, J. Opt. Soc. Am. B 22 (9), 1868 (2005)
[8]T. V. Amotchkina et al., “Measurement of group delay of dispersive mirrors with white-light interferometer”, Appl. Opt. 48 (5), 949 (2009)

(Suggest additional literature!)

See also: interferometers, coherence, chromatic dispersion, white light sources, Spotlight article 2008-02-22
and other articles in the categories optical metrology, photonic devices

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