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Updated: Jan 7, 2026

Implementation of a Reference Interferometer for Nanodetection
Published on: April 26, 2014
Ranging beyond synthetic wavelengths with an undersampled spectral signal using tunable wavelength laser
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Range extension achieved beyond the longest synthetic wavelength is possible by continuous tuning of the source wavelength and with the use of tilted interference for excess fraction extraction from a spectrally undersampled signal. This allows for the unique measurement of the extended range. For a correctly assumed fringe order for the initial source wavelength, the non-divergence of the estimated range as a function of wavelength tuning provides the potential range locations. These are further zeroed in by repeating the analysis by varying the tuning steps. A cascaded Michelson interferometer is used to uniquely measure the extended range as well as the spatial profile of the sample from a single set of wavelength scan. The excess fraction is accurately measured using the Fourier transform method of fringe analysis by virtue of tilted interference. With the support of sub-nanometer resolution in wavelength tuning, precise centimeter-scale ranging, along with micrometer-level profile resolution, is achieved.
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