17 August 1999 Sinusoidal wavelength-scanning interferometers using a superluminescent diode
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Proceedings Volume 3745, Interferometry '99: Applications; (1999) https://doi.org/10.1117/12.357778
Event: International Conference on Optical Metrology, 1999, Pultusk Castle, Poland
Two different sinusoidal wavelength-scanning (SWS) interferometers with a SWS light source using a superluminescent laser diode are proposed for step-profile measurement and real-time distance measurement, respectively. An optical path difference (OPD) longer than a wavelength is measured from detection of sinusoidal phase- modulation amplitude Zb of the interference signal that is proportional to the OPD and the scanning width 2b. In step-profile measurement, if measurement error in the OPD obtained from Zb is smaller than a half wavelength, this measured value of the OPD is combined with a fractional value of the OPD obtained from the conventional phase of the interference signal. This combination enables us to measure the OPD longer than a wavelength with a high accuracy of a few nm. In real-time distance measurement, the amplitude Zb is kept at a specified constant value for changes of OPD by controlling the scanning width 2b of the wavelength with a feedback system. The amplitude Zb is detected by processing the interference signal with electric circuits in real-time. The value of b is easily controlled in the SWS light source, and an OPD longer than a wavelength is measured from the value of b with an accuracy of about a wavelength.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Osami Sasaki, Norihiko Murata, Kazuhiro Akiyama, Takamasa Suzuki, "Sinusoidal wavelength-scanning interferometers using a superluminescent diode", Proc. SPIE 3745, Interferometry '99: Applications, (17 August 1999); doi: 10.1117/12.357778; https://doi.org/10.1117/12.357778

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