Robust Laser-Ultrasonic Interferometer Based on Random Quadrature Demodulation

The new interferometric scheme that was presented at last year QNDE conference for robust and sensitive detection of ultrasound in industrial environment has been further improved. The proposed architecture combines quadrature detection with detector arrays for multi‐speckle processing. The quadrature is reached tanks to the random phase distribution of the speckle light and the parallel signal processing is simplified by using an approximated demodulation technique based on signal rectification. Results demonstrating this new principle of operation and its performances are presented.