26 November 2007 Sinusoidal wavelength-scanning interferometers for shape measurements
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Abstract
Sinusoidal wavelength-scanning (SWS) interferometry is unique in that a time-varying interference signal contains phase-modulation amplitude Zb due to the SWS besides a conventional phase &agr;. A rough value of an optical path difference (OPD) longer than a wavelength is obtained from the amplitude Zb, which is useful for shape measurements of rough surfaces. By combing the two values of Zb and &agr;, an OPD longer than a wavelength can be measured with a high accuracy of the order of nanometer, which is useful for shape measurements of optical surfaces. As light sources of SWS interferometers a tunable laser diode with an external cavity is used and a superluminescent diode (SLD) is used with an acousto-optic tunable filter. A shape of a metal surface, a step shape of an optical surface, and a thin-film shape of optical surfaces are measured.
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Osami Sasaki, Osami Sasaki, } "Sinusoidal wavelength-scanning interferometers for shape measurements", Proc. SPIE 6829, Advanced Materials and Devices for Sensing and Imaging III, 682908 (26 November 2007); doi: 10.1117/12.757422; https://doi.org/10.1117/12.757422
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