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arXiv · 1912.05030

Multiple reflection assisted Laser Doppler Vibrometer setup for high resolution displacement measurement

Nikhil Kumar Pachisia·Kajal Tiwari·Ritwick Das
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Abstract

Non-intrusive displacement measurement technique has a distinct edge over displacement sensors working in contact mode. Laser Doppler Vibrometry based schemes (LDV) offer such an advantage. However, the measurements are limited up to $λ/4$, where $λ$ is the wavelength of optical source. An experimental design of high resolution non-intrusive displacement sensor working on the principle of basic LDV is being presented here. Resolution enhancement has been achieved through phase multiplication using multiple reflections within a high-Q cavity created by a vibrating surface and a high reflection mirror kept parallel to each other. Displacement of 72 $nm$ has been measured with an error range of $\pm 14$ $nm$ through direct counting of characteristic peaks in "half cycle" of the interferogram. The experimental design offers a straightforward route to measure displacement and the measurement resolution is mainly limited by the reflectivity and physical dimension of moving source.

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Nikhil Kumar Pachisia, Kajal Tiwari, Ritwick Das. 2019-12-09. Multiple reflection assisted Laser Doppler Vibrometer setup for high resolution displacement measurement. https://doi.org/10.1016/j.optcom.2020.125504

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