The system of double-optical-path ESPI for the vibration measurement

In this paper, a system of double-optical-path electronic speckle pattern i nterferometry (ESPI) for measuring larger vibration is proposed. This syste m combines the conventional ESPI optical path for measuring out-of plane vi bration and the de-sensitized optical path. It can be used to observe quali tatively and analyze quantitatively the vibration mode. At the same time, t he phase unwrapping is avoided. The anti-disturbance capability of this sys tem is high, so it can be used to analyze the vibration characteristics of complex and discontinuous structure in actual engineering. (C) 2000 Elsevie r Science Ltd. All rights reserved.