联合波叠加法的全息理论与实验研究

Investigation on holographic algorithm and experiment of combined wave superposition approach

当空间声场中同时存在多个相干声源时,运用常规近场声全息方法无法重建每个相干声源表面的声学信息,当然也无法预测每个声源单独产生的空间声场,相干声场的全息重建与预测已成为全息技术推广应用过程中亟待解决的问题.在提出联合波叠加法并将其应用于空间声场变换的基础上,对其进行了实验研究.通过对实际相干声场的全息重建与预测,验证了常规波叠加法在相干声场重建中的局限性、联合波叠加法在相干声场全息重建与预测过程的可行性和准确性,还研究了Tikhonov正则化方法在抑制声学逆问题的非适定性中的有效性和滤波系数的选择原则的可行性,以提高全息重建与预测的精度.

The general nerar-field acoustic holography （NAH） cannot reconstruct the surface acoustic information of each coherent acoustic source in coherent acoustic field, which has more than one acoustic sources with the same frequency, and they cannot realize holographic reconstruction and prediction of the independent acoustic field generated by one coherent acoustic source too. So the holographic reconstruction and prediction of coherent acoustic field has become the foremost problem to be resolved in the application of NAH. On the basis of the proposed combined wave superposition approach, an experiment is carried out to realize the holographic reconstruction and prediction of a coherent acoustic filed generated by two sound boxes. By this experiment, the feasibility and accuracy of combined wave superposition approach are demonstrated, the shortcoming of general wave superposition approach in holographic construction and prediction of coherent acoustic field are also demonstrated. The Tikhonov regularization method is proposed to control the ill-posedness of inverse acoustic problem, and the principle of filter coefficient selection is also studied. The experiment indicates that Tikhonov regularization method with appropriate filter coefficient can improve the precision of the holographic reconstruction and prediction.