Phase Measurement of Acoustic Wave Propagation in Double Channel Video Based Interferometry

Abstract

Sistem interferometer pengukuran fasa telah dibangunkan dengan mengubahsuai perbezaan fasa antara kedua–dua output interferometer Mach–Zehnder sebanyak 90°. Sistem dibangunkan bagi mengatasi masalah kesamaran anjakan fasa dalam kajian perambatan gelombang akustik dan profil tekanan seketika yang wujud bersama. Dua pasang imej dirakamkan dari kedua–dua output interferometer Mach–Zehnder semasa adanya dan ketiadaan gangguan gelombang akustik. Perubahan fasa keseluruhan interferograms dipetakan dan dianalisa secara berasingan dan serentak. Pemetaan fasa secara serentak memberikan keputusan yang lebih baik dan mengatasi masalah kesamaran. Kata kunci: Interferometri pengukuran fasa; perambatan gelombang akustik Phase measurement interferometer system was developed by modifying the phase difference between two outputs of Mach–Zehnder interferometer by approximately 90° out of phase. System is developed in order to overcome some ambiguity of fringe shift in studying acoustic wave propagation and associate transient pressure profile. Two set of images were captured from two outputs of Mach–Zehnder interferometer in the event of with and without acoustic wave disturbance. The phase change over the interferograms were mapped and analysed separately and simultaneously. Simultaneous phase mapping gives better result and overcome ambiguity problem. Key words: Phase measurement interferometry; acoustic wave propagation