Application of wavelet filtering for vibration analysis using digital speckle pattern interferometry

We have investigated the utility of wavelet filters for enhanc- ing contrast in the digital speckle pattern interferometric fringes obtained from a vibrating loudspeaker diaphragm and from the vibrating bracket of an electric motor. Experimental results reveal that use of properly chosen other filters along with the wavelet filter gives better enhancement. Our investigations also show that if the data are preprocessed by median filtering before implementing the wavelet filtering, then a weakly diffusing object requires a higher-kernel filter and strongly diffusing object requires lower-kernel one.