Abstract: A method of reading out data from a domain expansion data storage such as a MAMMOS magneto-optic disk (1) which includes a data storage layer in which data is stored in the form of magnetic marks, and an expansion layer capable of copying and expanding domains from the storage layer, the system applying a first radiation beam (7), having a first spot size on the disk, in order to initiate copying of a domain from the storage layer to the expansion layer, and applying a second radiation beam (9), having a second spot size larger than the first spot size on the disk, in order to read out data from the expansion layer.