Abstract: An application of a client includes a proof data generation device, a command generation device, and a command issuing device. A command and proof data are sent to a server from the application of the client, and a command management device of the server receives them. A proof data verification device verifies the access right of a user to the application on the basis of the proof data, and enables a data storage device to be accessed in accordance with the command, if the verification is successful. The data storage device, used instead of a commonly used hard disk drive, includes a phase change type optical memory or a phase separation type optical memory to execute write once recording. Thus, the access to the data storage device is flexibly controlled.

Abstract: An optical recording medium for a land & groove recording method capable of suppressing crosstalk and cross-erase (increase of jitter) upon increasing the capacity by the increase of track density, wherein a depth for a groove is made greater than 60 nm, at least one of a protection layer, a recording layer and an interference layer is formed to a layer thickness different between the groove and the land, such that reflectance to an optical beam upon irradiation of the optical beam to a predetermined track comprising the land or the groove is equal with each other between a portion in a recorded state and a portion in a unrecorded state of an adjacent track adjacent with the predetermined track, and a land wall for one of the protection layer, the recording layer and the interference layer is made thinner than the thickness of the groove and the land or removed.

Abstract: An optical recording medium is disclosed, which comprises a substrate having thereon a recording layer which is capable of forming regions having an increased reflectivity by spinodal decomposition of the recording layer upon application thereto of energy of a threshold value or higher. Writing of information is achieved by irradiating the recording layer with no phase separation caused by spinodal decomposition with an energy beam having an intensity causing spinodal decomposition-induced phase separation in accordance with the information to be written. Reading of the information, on the other hand, is achieved by irradiating the recording layer with phase separation caused by spinodal decomposition with an energy beam having an intensity causing no spinodal decomposition-induced phase separation. The medium and the recording system using the same exhibit high sensitivity, high reflectivity, and high contract and conform to the CD or LD standard.