A diffractive beam expander comprising: - a substantially planar waveguiding substrate, - an input grating to provide an in-coupled beam propagating within said substrate by diffracting light of an input beam into said substrate, - a first deflecting grating portion to provide a first deflected beam by diffracting a part of said in-coupled beam such that the difference between the azimuth angle (α 1) of said first deflected beam and the azimuth angle (φ C) of said in-coupled beam 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 by diffracting a part of said in-coupled beam such that the difference between the azimuth angle (α 2) of said second deflected beam and the azimuth angle (φ C) of said in-coupled beam 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 by diffracting light of said first deflected beam, - a second restoring grating portion to provide a second restored beam, said second restored beam being substantially parallel to said first restored beam, wherein a part of the in-coupled beam 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 by diffracting light of said first restored beam, said non-diffracted beam and said second restored beam out of said substrate, said output beam being substantially parallel to said input beam. - a substantially planar waveguiding substrate, - an input grating to provide an in-coupled beam propagating within said substrate by diffracting light of an input beam into said substrate, - a first deflecting grating portion to provide a first deflected beam by diffracting a part of said in-coupled beam such that the difference between the azimuth angle (α 1) of said first deflected beam and the azimuth angle (φ C) of said in-coupled beam 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 by diffracting a part of said in-coupled beam such that the difference between the azimuth angle (α 2) of said second deflected beam and the azimuth angle (φ C) of said in-coupled beam 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 by diffracting light of said first deflected beam, - a second restoring grating portion to provide a second restored beam, said second restored beam being substantially parallel to said first restored beam, - an output grating to provide an out-coupled beam by diffracting light of said first restored beam, said non-diffracted beam and said second restored beam out of said substrate, said output beam being substantially parallel to said input beam.