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13 September 2010Vibration phase measurements using holographic optical elements
based electronic speckle pattern interferometry
The application of an out-of-plane sensitive electronic speckle pattern interferometer (ESPI) using holographic optical
element (HOE) to vibration amplitude and phase mapping is reported. The novelty of the proposed system is the use of a
speckle reference wave stored in a reflection holographic optical element (HOE). The incorporation of a HOE minimizes
the alignment difficulties. The HOE based ESPI system is compact containing only a diode laser, HOE and a digital
CMOS camera. The measurement technique is a combination of time averaged ESPI and reference beam phase
modulation in an unbalanced interferometer. The reference beam phase modulation is implemented by modulating the
drive current of the diode laser. The presented HOE based ESPI system is easy to align and compact and thus suitable for
industrial non-destructive testing and vibration analysis.