Abstract: The invention provides for a recording method comprising the steps of modulating a first light beam; directing a second light beam to interfere with the first light beam to produce an interference pattern in a region of a recording medium; forming an optical device in the medium responsive to the interference pattern, wherein optical characteristics of the optical device are varied responsive to variations in the interference pattern. A method of playback, a recording and/or reading head and data carriers are also claimed. An example relates to a full diffraction analogy of gramophone recording. The interference of two beams, one of which is functionally linked to an audio signal, results in a change of the diffractive structure that instantly reflects the change of the input signal. On playback the diffracted light beam oscillates in the same way as the gramophone needle would vibrate. Another aspect of the disclosure relates to multilevel digital recording using holographic and/or diffractive structures.