A display for displaying an image to a viewer, the display comprising: (a) an image generator having an illumination subsystem generating illumination of at least a first color, said image generator employing said illumination to generate an image; (b) projection optics for projecting illumination from the image for display to the viewer, said projection optics comprising: (i) collimating optics for collimating said illumination from said image generator to generate a collimated image, and (ii) a light-guide optical element having a pair of parallel major external surfaces (508, 510) for guiding the collimated image within the light-guide optical element by internal reflection, the light-guide optical element having a coupling-out configuration for redirecting at least part of the collimated image towards the viewer, characterized in that said illumination subsystem comprises a first laser generating a first laser beam of the first color with a first polarization and a second laser generating a second laser beam of the first color with a second polarization, said first and second polarizations being in a parallel state, said first laser beam and said second laser beam have respectively a first wavelength and a second wavelength, said first and second wavelengths differing by less than 5%, and wherein said projection optics comprises a length of birefringent material configured to differentially rotate said first and second polarizations from said parallel state to a substantially orthogonal state at an input of the light-guide optical element, said image generator comprises a polarization-modifying spatial light modulator illuminated by said first and second laser beams, and said birefringent material is deployed in a light path from said collimating optics to said light-guide optical element. (a) an image generator having an illumination subsystem generating illumination of at least a first color, said image generator employing said illumination to generate an image; (b) projection optics for projecting illumination from the image for display to the viewer, said projection optics comprising: (i) collimating optics for collimating said illumination from said image generator to generate a collimated image, and (ii) a light-guide optical element having a pair of parallel major external surfaces (508, 510) for guiding the collimated image within the light-guide optical element by internal reflection, the light-guide optical element having a coupling-out configuration for redirecting at least part of the collimated image towards the viewer, (i) collimating optics for collimating said illumination from said image generator to generate a collimated image, and (ii) a light-guide optical element having a pair of parallel major external surfaces (508, 510) for guiding the collimated image within the light-guide optical element by internal reflection, the light-guide optical element having a coupling-out configuration for redirecting at least part of the collimated image towards the viewer, said illumination subsystem comprises a first laser generating a first laser beam of the first color with a first polarization and a second laser generating a second laser beam of the first color with a second polarization, said first and second polarizations being in a parallel state, said first laser beam and said second laser beam have respectively a first wavelength and a second wavelength, said first and second wavelengths differing by less than 5%, and wherein said projection optics comprises a length of birefringent material configured to differentially rotate said first and second polarizations from said parallel state to a substantially orthogonal state at an input of the light-guide optical element, said image generator comprises a polarization-modifying spatial light modulator illuminated by said first and second laser beams, and said birefringent material is deployed in a light path from said collimating optics to said light-guide optical element.