Studies Of Aperture Synthesis And Sub-hologram Combination Method In Digital Holography

Recently, digital holography is given more attention at home and abroad along with the development of the computer technology, electronic record device and the image processing technique. At the same time, a critical defect—low resolution is exposed. This is because of the small recording area of the electronic record device (CCD), so the recorded digital hologram resolution is very low and the reconstruction image quality is affected greatly.In this paper, a synthetic aperture digital holography is proposed to solve the above problem. The synthetic aperture technique can be used to increase the equivalent recording aperture of CCD camera. By two methods—movement of CCD camera and object, the aperture is synthesized without extra main experimental equipment. The recorded sub-digital holograms are combined by intensity correlation theory. The reconstruction result shows that by the two recording method, the reconstruction image of synthetic aperture digital hologram can be both improved.The main contents of this paper can be generalized as follow:1) The theory of holography, digital holography, synthetic digital holography and digital image correlation technique are summarized;2) The theory of synthetic aperture digital holography method by movement of object and CCD is described;3) Based on intensity correlation theory, the method of sub-digital hologram combination is researched, an image mosaicking program is programmed and the error analysis of the program is done on condition of different size of template and intensity chance between the sub-digital holograms, etc;4) The two synthetic aperture digital holography recording systems—by translation of CCD and recording object are designed under existing conditions of our laboratory;5) The two dimension aperture synthesis is achieved in digital holography and the two dimension synthetic aperture digital hologram is reconstructed digitally;6) The synthetic aperture digital hologram obtained by combination of the sub-digital holograms is reconstructed; the reconstruction result shows that the reconstruction image resolution can be improved by the two recording systems and can also be used to record larger object;7) The existing problems in synthetic aperture digital holography are discussed and the corresponding solutions are represented.