The Application Of Digital Processing In Holographic Storage

The volume holographic storage is now developing to the field of digital storage. Since the stored objects are gray images, digital image processing technique is of significance in volume holographic storage. In this thesis, we introduced the method of digital image processing and the like to investigate the basic issues about the coupled-wave theory of the diffraction of volume gratings, the record and readout of pixel-matched system and its error code analysis, and at last, the performance of the scattering noise of holographic recording media.Firstly, the assumption about the direction of diffracted beam under off-Bragg conditions in volume gratings has been a controversial issue, and since the limitation of small selective angle, the direction of diffracted beam has not been experimently measured. In this thesis, we accurately measured the direction of diffracted beam as functions of readout angle, under off-Bragg condition. The results show that, the direction of diffracted beam does not simply accord with the assumption of Kogelnik or Heaton et al, but has a close relation with the recording angles of reference beam and object beam. Especially, in the case of reflection gratings, when the grating slant angle is larger, the diffraction direction agrees more with Kogelnik's assumption, and vice visa. Based on these results, we amended the assumption of the direction of diffracted beam in one-dimensional coupled wave theory, and induced an off-Bragg parameter in the direction of diffracted wave vector. Thus, the problem that the diffracted wave vector might be different from the readout beam vector under off-Bragg condition can be solved. The diffraction efficiency curve derived by using this new assumption is quite similar with one-dimensional coupled wave theory in paraxial recording condition.In volume holographic data storage, pixel-matched recording and readout have always been a challenge, and to achieve low bit-error-rate (BER) is more important. We discussed the influence of aperture on image quality in 4f system by numerical calculation, and found that the image quality oscillatorily increased, as the size of aperture increasing. Later, we realized the pixel match of data mask and SLM to...