A source arrangement for providing an electromagnetic radiation comprises at least one emitter of the electromagnetic radiation (2). The source arrangement also comprises at least one spectral separating arrangement (4) configured to physically separate one or more components of the electromagnetic radiation based on a frequency of the electromagnetic radiation. The source arrangement also comprises a further arrangement which is configured to receive at least some of the one or more components, and modify at least one characteristic of the received one or more components to forward at least one signal which is associated with one or more further components of the electromagnetic radiation. The source arrangement further comprises at least one continuously rotating optical arrangement (24) which is configured to receive the at least one signal. The source arrangement also further comprises at least one beam selecting arrangement configured to receive the at least one signal.