Investigation Of Acoustic Levitation Field Based On Laser Holographic Interferometry

Optical holography is an experimental technique which can record and reconstruct the whole information of object wave front, and has been applied to fluid field investigation. With the birth of computer, the development of assistant equipment and the advance of image processing technique, digital holography technology reached a new level. Both of them have many outstanding advantages in the visualization and measurement of acoustic levitation field. The theory of holography and its applications in acoustic levitation field reconstruction and optical metrology are presented in this thesis.(1) Theoretical analysis foundation for holography reconstruction, namely, Fourier transform theory is presented. With the diffraction theory of plane wave, frequency domain algorithm in object field reconstruction is discussed. Furthermore, holography principle in fluid field measurement is introduced. The method of three-dimensional reconstruction is provided by Abel transform algorithm.(2) The properties and resonant modes of single axis acoustic levitation system are presented. At the same time, the plane sound wave mode, the Gauss sound wave mode and the bicylinder sound wave mode are systemically calculated and analyzed.(3) The operation for visualization and reconstruction of acoustic levitation field is experimentally demonstrated. The satisfactory conclusions are obtained through a series of contrast experiments. Phase multiplied experiment setup is designed, which can solve the problem of feeblish phase in acoustic levitation field.(4) The numerical reconstruction of acoustic levitation field reconstruction is achieved by using frequency domain algorithm of digital holography reconstruction algorithm. The elaborate field configuration is attained by phase multiplication theory. The reconstruction of index field distribution and pressure field distribution are accomplished by means of combining Abel transform theory with program language.