An apparatus for filtering an electromagnetic radiation comprises at least one spectral separating arrangement (4) configured to angularly separate one or more components of the electromagnetic radiation based on a frequency of the electromagnetic radiation. The apparatus also comprises at least one angularly deflecting optical arrangement (24) that includes a pivot point, and is configured to receive the one or more components of the electromagnetic radiation to generate at least one signal associated with the one or more components. The apparatus further comprises at least one optical imaging arrangement (20, 22) configured to directly receive from the spectral separating arrangement the one or more components of the electromagnetic radiation, and generate an image of one or more dispersive elements associated with the one or more components toward the deflecting optical arrangement.