Patent ID: 7538920
Filing Date: 2009-05-26
Classification: G03H,G11B,G11C

Abstract:
1. A reproduction apparatus capable of reproducing, from a hologram recording medium on which digital data are recorded as an element hologram formed from interference fringes generated by interference of imaged data of the digital data as object light with reference light, the digital data, comprising: image pickup means for picking up an image of the element hologram as a two-dimensional image; storage means for storing the two-dimensional image picked up by said image pickup means; partial extraction means for extracting a predetermined region of the two-dimensional image picked up by said image pickup means, the predetermined region having stored therein a synchronization signal of data of a form different from that of data produced by performing a predetermined modulation process for the digital data, the digital data being converted into two-dimensional code symbols by dividing the digital data into blocks for each predetermined data amount and performing a predetermined modulation process for the blocks, and the synchronization signal has a data amount equal to that of plural ones of the two-dimensional code symbols; decision means for deciding a tracking state with regard to the element hologram from the two-dimensional image extracted by said partial extraction means; image fetching processing means for fetching, where it is decided by said decision means that the two-dimensional image picked up by said image pickup means can be fetched, the two-dimensional image picked up by said image pickup means into said storage means; signal processing means for performing signal processing for the two-dimensional image stored in said storage means to reproduce the digital data; and control means for controlling said partial extraction means, decision means, image fetching means and signal processing means to extract the predetermined region from the two-dimensional image picked up by said image pickup means, decide the tracking state of the element hologram from the extracted two-dimensional image, fetch the two-dimensional image picked up by said image pickup means into said storage means based on the result of the decision and reproduce the digital data from the two-dimensional image stored in said storage means.