Real-time displacement measurement with a two-wavelength sinusoidal phase-modulating laser diode interferometer.
A two-wavelength interferometer that uses two separate modulating currents with different phases but the same frequencies to detect a greater degree of object displacement in real time is proposed and demonstrated. The measurement error was 57 nm, roughly 1/80 of the synthetic wavelength. We have confirmed that this modulating technique enables us to equip our prototype interferometer with a simple feedback-control system that eliminates external disturbance.
Suzuki
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T
Faculty of Engineering, Niigata University, 8050 Ikarashi 2, Niigata 950-2181, Japan.
Kobayashi
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Sasaki
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O