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Proceedings Paper

Directional-sensitive differential laser Doppler vibrometry for in-plane motion measurement of specular surface
Author(s): Kusuma Agusanto; Gih-Keong Lau; Kun Wu; Ting Liu; Chuangui Zhu; Ling Yuan
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Paper Abstract

A new method for measuring in-plane vibration velocity of glossy and specular surface using differential laser Doppler vibrometer (LDV) is proposed in this work. A standard tangential LDV using similar differential configuration is only able to measure in-plane velocity of objects with rough surface, due to its inherent on-axis optical design that collects backscatter light along its optical axis. The proposed method adopts an off-axis detection scheme, in which the photodetector is decoupled from LDV, and placed along the dominant direction of the scattered light. For optimal placement, the bidirectional reflectance distribution function (BRDF) of the sample must be considered ideally, but in our measurement tests, the off-axis detection along the direction of specular reflection is sufficient to obtain good measurement results. Another advantage with this setup is that it also works with the objects with rough surface. Experimental works using the standard tangential LDV and a prototype of this method were conducted to measure the in-plane motion of four different samples representing rough, glossy and mirror-like surface. An electrodynamic shaker was used to provide the in-plane motion of the samples at three different frequencies. A single point axial vibrometer was used to validate the in-plane velocity of the measurement from both in-plane LDVs. Some preliminary results showed that the in-plane motion of the object with glossy and specular surface can be measured using the proposed method.

Paper Details

Date Published: 4 March 2015
PDF: 6 pages
Proc. SPIE 9302, International Conference on Experimental Mechanics 2014, 93020V (4 March 2015); doi: 10.1117/12.2075845
Show Author Affiliations
Kusuma Agusanto, Nanyang Technological Univ. (Singapore)
Sunny Instruments Singapore Pte Ltd. (Singapore)
Gih-Keong Lau, Nanyang Technological Univ. (Singapore)
Kun Wu, Sunny Instruments Singapore Pte Ltd. (Singapore)
Ting Liu, Sunny Instruments Singapore Pte Ltd. (Singapore)
Chuangui Zhu, Sunny Instruments Singapore Pte Ltd. (Singapore)
Ling Yuan, Sunny Instruments Singapore Pte Ltd. (Singapore)

Published in SPIE Proceedings Vol. 9302:
International Conference on Experimental Mechanics 2014
Chenggen Quan; Kemao Qian; Anand Asundi; Fook Siong Chau, Editor(s)

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