Patent ID: 8718414

Claim:
An acousto-optical filter element comprising: an acousto-optical crystal having an acoustic signal transmitter for generating acoustic signals in the acousto-optical crystal, the acousto-optical crystal configured to selectively spatially deflect light of a target wavelength from an input light beam of a broadband coherent light source entering into the acousto-optical crystal, as a function of a high frequency applied to the acoustic signal transmitter, and to thereby produce a target light beam having a desired target wavelength; and a spatial filter element located in the target light beam, the spatial filter element configured to selectively suppress the intensity of a portion of the target light beam in a plane perpendicular to the propagation direction of the target light beam, the spatial filter element comprising an optical waveguide and a lens element, an opening of the optical waveguide cutting off unwanted side modes of a spatial transfer function of the target light beam.