A diffractive beam expander comprising: - a substantially planar waveguiding substrate , - an input grating to provide an in-coupled beam (B1) propagating within said substrate by diffracting light of an input beam (B0) into said substrate , - a first deflecting grating portion to provide a first deflected beam (U1) by diffracting a part of said in-coupled beam (B1) such that the difference between the azimuth angle (α 1 ) of said first deflected beam (U1) and the azimuth angle (φ C ) of said in-coupled beam (B1) is negative, said first deflecting grating portion comprising substantially linear diffractive features (F 21a ), - a second deflecting grating portion to provide a second deflected beam (U2) by diffracting a part of said in-coupled beam (B1) such that the difference between the azimuth angle (α 2 ) of said second deflected beam (U2) and the azimuth angle (φ C ) of said in-coupled beam (B1) is positive, said second deflecting grating portion comprising substantially linear diffractive features (F 22a ), the diffractive features (F 22a ) of said second deflecting grating portion having a different orientation than the diffractive features (F 21a ) of said first deflecting grating portion , - a first restoring grating portion to provide a first restored beam (V1) by diffracting light of said first deflected beam (U1), - a second restoring grating portion to provide a second restored beam (V2), said second restored beam (V2) being substantially parallel to said first restored beam (V1), wherein a part of the in-coupled beam (B1) is configured to propagate within the substrate without being diffracted by said first deflecting grating portion , said second deflecting grating portion , said first restoring grating portion and said second restoring grating portion to provide a non-diffracted beam, and - an output grating to provide an out-coupled beam (B2) by diffracting light of said first restored beam (V1), said non-diffracted beam and said second restored beam (V2) out of said substrate , said output beam (B2) being substantially parallel to said input beam (B0). - a substantially planar waveguiding substrate , - an input grating to provide an in-coupled beam (B1) propagating within said substrate by diffracting light of an input beam (B0) into said substrate , - a first deflecting grating portion to provide a first deflected beam (U1) by diffracting a part of said in-coupled beam (B1) such that the difference between the azimuth angle (α 1 ) of said first deflected beam (U1) and the azimuth angle (φ C ) of said in-coupled beam (B1) is negative, said first deflecting grating portion comprising substantially linear diffractive features (F 21a ), - a second deflecting grating portion to provide a second deflected beam (U2) by diffracting a part of said in-coupled beam (B1) such that the difference between the azimuth angle (α 2 ) of said second deflected beam (U2) and the azimuth angle (φ C ) of said in-coupled beam (B1) is positive, said second deflecting grating portion comprising substantially linear diffractive features (F 22a ), the diffractive features (F 22a ) of said second deflecting grating portion having a different orientation than the diffractive features (F 21a ) of said first deflecting grating portion , - a first restoring grating portion to provide a first restored beam (V1) by diffracting light of said first deflected beam (U1), - a second restoring grating portion to provide a second restored beam (V2), said second restored beam (V2) being substantially parallel to said first restored beam (V1), - an output grating to provide an out-coupled beam (B2) by diffracting light of said first restored beam (V1), said non-diffracted beam and said second restored beam (V2) out of said substrate , said output beam (B2) being substantially parallel to said input beam (B0). <EOS>