Abstract: The invention relates to a method and a device for producing a hologram in an optical medium, particularly for storing data in the optical medium. In the method, the hologram is produced in the optical medium using laser beams, wherein the laser beams are formed from a laser beam emitted by a free-running semiconductor laser, are directed onto the optical medium, optionally contradirectionally, and at least partially spatially overlap in the optical medium. For producing holograms using inexpensive components with a high contrast, the invention provides for arranging the reflection unit (15) such that the optical path length (?x) between the focus of the laser beam in the storage medium (10) and the reflecting surface of the reflection unit (15) satisfies the condition ?x=0.5*?s*a in the region of the optical axis, wherein a is a natural number greater than or equal to 1 and ?s is a distance between neighboring coherence centers of the laser beam produced by the semiconductor laser (16).