Focusing system comprising acousto-optic deflectors for focusing an electromagnetic beam

Focusing system for focusing an electromagnetic beam for three-dimensional random access applications, the system comprising a first pair (10) of acousto-optic deflectors (12, 12′) for focusing an electromagnetic beam in an X-Z plane, and a second pair (20) of acousto-optic deflectors (22, 22′) for focusing an electromagnetic beam in a Y-Z plane being substantially perpendicular to the X-Z plane, characterised in that the second pair (20) of acousto-optic deflectors (22, 22′) is arranged between the acousto-optic deflectors (12, 12′) of the first pair (10) of acousto-optic deflectors, such that the acousto-optic deflectors together form an array of deflectors with acousto-optic deflectors (12, 12′) of the first pair (10) being the first and fourth acousto-optic deflectors in the array and acousto-optic deflectors (22, 22′) of the second pair (20) being the second and third acousto-optic deflectors in the array.