Image projector with polarizing catadioptric collimator

An image projector for injecting a collimated image into an entrance aperture of a lightguide, the image projector comprising:

• (a) a polarization-modifying spatial light modulator (SLM) deployed for modifying a polarization of illumination according to image data supplied to said SLM;
• (b) an illumination arrangement for illuminating said SLM with polarized illumination;
• (c) a polarization-selective element deployed to select light from said SLM corresponding to an image;
• and
• (d) collimating optics for collimating the light corresponding to the image so as to provide the collimated image at the entrance aperture of the lightguide, wherein said collimating optics includes a polarizing catadioptric arrangement comprising, sequentially:
• (i) a first quarter-wave plate;
• (ii) a first optical surface implemented as a partial reflector;
• (iii) a second quarter-wave plate;
• and
• (iv) a second optical surface implemented as a polarization-selective reflector,
• wherein at least one of said first and second optical surfaces is implemented as a non-planar surface with optical power which acts twice on the light, once as a refractive lens surface and once as a reflective lens.