Precise Displacement Measurements Using Phase Information of 40 kHz Ultrasonic Waves in Pinhole-Based Air-Coupled Ultrasonic System

概要

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Noncontact precise displacement measurements, including surface profiling, were demonstrated using the phase information of narrow-band 40 kHz continuous waves (wavelength $\lambda=9$ mm) in a pinhole-based air-coupled ultrasonic system beyond the diffraction limit. Real-time displacement measurements with a distance resolution of $\lambda/900{,}000$ (10 nm) were accomplished using a highly sensitive phase variation when the distance between the pinhole and the surface of an object was in the range from approximately 5 to 10 μm. To extend the working distance of our system while maintaining a high resolution, an automatic distance control system was constructed and introduced in our system. Using this advanced system, a surface topographical profile of 16 μm height was successfully measured, while maintaining maximum phase sensitivity. These results demonstrate the usefulness of our system when applied to noncontact precise displacement measurements.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2007-07-30