Review: Digital Acousto-Optic Holography

The use of acoustic waves to detect the internal structure of non-transparent objects is a common technical approach, but the inherent defects of acoustic waves and the inad-equacy of imaging algorithms have led to unsatisfactory results of acoustic imaging for practical engineering applications. Digital holographic inspection techniques enable high-resolution imaging of the surface of objects, but hologram recording systems based on visible wavelength light sources do not provide direct access to the interior of non-transparent objects. Digital acousto-optic holography combines the advantages of good penetrability of acoustic waves, the high-resolution capability of optical holog-raphy, and digital imaging and processing technology, making it possible to image or detect the internal structure of non-transparent objects at high resolution. In this paper, the basic definition, key theories, experimental systems, and problem-solving of digital acousto-optic holography are fully elaborated, analyzed, and discussed. A review of the related technologies and their research development is presented.