Reflection Acoustic Microscopy for Micro-NDE.

The reflection acoustic microscope has evolved to a stage where it can be regarded as a powerful laboratory tool for an important class of problems in non destructive examination. The report is concerned with an extension of the capability of the acoustic microscope for such applications. Acoustic microscopy involves imaging in highly attenuating media. There has for long been a controversy on whether the losses enhance or degrade the resolution of the microscope. The author has developed a novel analytical technique - an extension of Fourier optics - for analyzing this problem. Results obtained show that with losses i The resolution deteriorates ii The sidelobe levels at the focal plane are reduced and iii The depth of focus of the lens is reduced.