Abstract: In a method for optical data storage with high density, there are employed as the data carrying medium a number of flat, thin memory components in the form of cards or discs. Two or more of the memory components are arranged in a stack, thus enabling each individual memory component to be manoeuvred in relation to the other memory components by means of a manoeuvring device, and a given memory component is moved in relation to the other memory components in the stack in order to write or read data in a data carrying area on the memory component, which can be addressed optically during the write or read operation without interference from the other memory components. A data carrying medium for use with the method for optical data storage with high density comprises a number of flat, thin memory components in the form of cards or disks.

Abstract: In an optical data storage medium with a storage area formed from a transparent, homogenous base material and with a number of optically active structures at one side of the storage area, the optically active structures are diffractive optical elements which can focus a beam of light incident on the storage area on to one or more points in the storage area and/or a redirected beam of light or emitted light radiation from this or these points on to a point outside the optical storage medium. During writing/reading of data in the storage medium, the diffractive optical elements are used for focusing the write/read beam in order to generate a data carrying structure or read data stored in such a data carrying structure, respectively.