Recording medium, reproducing apparatus, and reproducing method

Abstract

A recording medium records therein image data for distributing contents as element holograms with interference fringes generated by interference between an object beam representing the image data and a reference beam. The image data to be distributed which are recorded as the element holograms in the recording medium are reproduced by applying reference beams to the recording medium.

Description

CROSS REFERENCES TO RELATED APPLICATIONS [0001] The present invention contains subject matter related to Japanese Patent Application JP 2005-148420 filed in the Japanese Patent Office on May 20, 2005, the entire contents of which being incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] The present invention relates to a recording medium in the form of a hologram for recording data based on fringes produced by interference between an object beam from an image representing the data and a reference beam, and an apparatus for and a method of reproducing data recorded in the recording medium. [0003] There are known in the art holographic recording mediums for recording various data based on fringes produced by interference between an object beam and a reference beam. It is also known in the art that the holographic recording mediums can have a high recording density for large storage capacity. The holographic recording mediums are considered to be useful as large-capaci...

AI Technical Summary

Benefits of technology

The present invention provides a recording medium and an apparatus for stably reproducing data from the hologram memory with a simple arrangement. The recording medium includes a first element hologram and a second element hologram that overlaid each other, and the second element hologram has a portion remaining unoverlaid by the first element hologram. The apparatus includes a reference beam applying means for applying reference beams to the recording medium at different angles, a reproduced image detecting means for detecting hologram images and outputting reproduced image signals, a timing detecting means for detecting scanning times for scanning the element holograms, and a control means for controlling the reference beam applying means and the reproduced image detecting means. The technical effects of the invention include a large storage capacity, easy duplication, and stable reproduction of recorded data.

Problems solved by technology

In addition, the shift multiplexing and angle multiplexing processes make it difficult to manufacture hologram readers inexpensively in a simple structure as the processes require reproducing apparatus compatible with them.

For example, if data is recorded in a hologram memory according to the angle multiplexing process, then the hologram reader needs to have a structure for applying a reproducing reference beam at various angles to the hologram memory, and hence is large in size and high in cost.

The shift multiplexing process is also disadvantageous in that it is difficult to produce a large number of duplicates according to a contact copying process.

Though shift multiplexing and angle multiplexing are useful for a system with a very large storage capacity, they are not suitable for a system for distributing a large number of hologram memories to easily provide various data to the general user.

Factors that are to be taken into account in such a recording process are a certain recording density, i.e., a storage capacity, and a crosstalk problem.

Conversely, if element holograms are positioned at sufficiently spaced intervals for reducing crosstalk, then an intermittent signal is produced from the identification patterns and such an intermittent signal is not appropriate as a servo signal.

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