23 June 1995 Optical implementation of frequency domain analysis for white-light interferometry
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Abstract
The purpose of recent developments of profilometry by using white light interferometry is to provide new tools for the analysis of rough samples which when studied by monochromatic phase-shifting interferometry, may cause phase calculation ambiguities. The usual way to perform depth measurements by white light interferometry is to analyze the coherence-limited interference fringes while the optical path difference is scanned. The method proposed here does not use optical path difference scanning. A spectroscopic device is used instead to separate the interference intensities associated to each spectral component of the light source. Phase variations due to wavelength change are proportional to the optical path difference and allows depth measurement to be performed without axial scanning. The profile of one line of the inspected sample is obtained from only one 2D interferogram. In this 2D interferogram one direction corresponds to the inspected direction of the surface while the other one is the chromatic axis which allows phase to change with wavelength. Experimental results show the ability of the proposed method to obtain the profile of 1D surface with nanometric resolution.
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Patrick Sandoz, Herve Perrin, Gilbert M. Tribillon, Jose E. Calatroni, Antonio L. Guerrero, Carmen Sainz, Raphael Esacalona, "Optical implementation of frequency domain analysis for white-light interferometry", Proc. SPIE 2545, Interferometry VII: Applications, (23 June 1995); doi: 10.1117/12.212650; https://doi.org/10.1117/12.212650
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KEYWORDS
Phase shift keying

Phase measurement

Light sources

Modulation

Optical interferometry

Phase interferometry

Phase shifting

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