A planar optical system for wide field-of-view polychromatic imaging includes a planar waveguide including two plane parallel faces, an entry coupler including a first diffraction grating, and an exit coupler including a second diffraction grating. The diffraction gratings are low line density diffraction gratings that have a pitch greater than the wavelength of use such that the grating is adapted to couple an entry beam having a mean angle of incidence i0 ranging between 30 to 60 degrees into the waveguide by positive first order (+1) diffraction, the coupled beam defining an internal angle of incidence greater than the angle of total internal reflection and less than γ=80 degrees, and the second grating is adapted to receive the coupled beam and to diffract it out of the waveguide by negative first order (−1) diffraction at a mean exit angle i1 ranging between 30 to 60 degrees.