Device for applying light to an inner surface of a cylinder and beam transformation device for such a device

A device ( 1 ) for applying light ( 4 ) to an inner surface ( 2 ) of a cylinder ( 3 ), comprising a homogenizer ( 14 ), into which light ( 4 ) can enter and from which the light ( 4 ) can exit, wherein the homogenizer ( 14 ) has a cylindrical internal surface ( 15 ), on which the light ( 4 ) can be reflected after entering and before exiting, and also comprising ways for introducing light ( 4 ) into the homogenizing means ( 14 ), and focusing arrangements, which can focus light ( 4 ) exiting from the homogenizer ( 14 ) onto the inner surface ( 2 ) of the cylinder ( 3 ) to which light ( 4 ) is to be applied.