Combination Compensation Method to Improve the Tolerance of Recording Medium Shrinkage in Collinear Holographic Storage

Holographic optical storage has great potential for enormous data storage, although the recording medium can cause dimensional change, which can deteriorate the quality of the reconstructed hologram. Compensation in traditional off-axial holographic storage systems is sensitive to vibration and requires high precision. In contrast, a collinear system is more compact with better stability, and its compensation would be different. In this paper, the combination compensation method for compensating for the dimensional change of the recording medium by simultaneously adjusting the reading light wavelength and the focal length of the objective lens is established, which was implemented in a collinear system for a high dimension-change-rate (sigma) of the medium condition. Its compensation effects for the lateral dimension change and the vertical dimension change were compared as well. The results show that the bit error ratio of the reconstructed hologram could be decreased to 0 for both of the dimensional change conditions with a large adjustment scope under sigma = 1.5%. Compared with the compensation method, in which only the focal length or the wavelength are adjusted, this combination compensation method can enlarge the compensation scope and improve the tolerance of the recording medium shrinkage in a collinear holographic storage system.