Device and method for microstructuring a storage medium and storage medium with a microstructured area

The device has a radiation source (4) for producing partially coherent beam from electromagnetic radiation. A modulator (6) is provided with a multiple individually switchable modulator elements. A beam-forming optical element (8) for illuminating the modulator. A reducing optical element (10) for reducing the beam radiated by the modulator. The reducing optical element is configured with limited diffraction and that the element (10) produces a surface reduction of 25 from the surface of the individual modulator elements. Independent claims are included for the following: (1) controlling method for a device for microstructuring of storage medium (2) Storage medium has an optically changeable layer (3) auto focusing device for an optical imaging of a writing device for the microstructuring of a storage medium (4) auto focusing method for an optical imaging of a writing device for the microstructuring of a storage medium and (5) operating point determination method of a device for structuring of a storage medium (6) auto focusing method for an optical imaging of a writing device for the microstructuring of a storage medium.