Vibration phase measurements using holographic optical elements based electronic speckle pattern interferometry

摘要

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.