Speckle-Reduced Direct-Retina Holographic Projector Including Multiple Spatial Light Modulators

A direct-retina holographic projection system comprising:

• a first spatial light modulator configured to receive a beam of light from a light source and dither the beam of light at a predetermined frequency to provide a plurality of instances of the beam of light;
• a second spatial light modulator configured to receive the plurality of instances of the beam of light from the first spatial light modulator, display an encoded phase hologram of a graphic image to be projected, and diffract the plurality of instances of the beam of light to provide a plurality of instances of the encoded phase hologram with same graphic information as the graphic image but multiplied with a plurality of dithered wavefronts, wherein the second spatial light modulator directs the plurality of instances of the encoded phase hologram directly at a reflector to be seen by the eye of the viewer without forming a real image on a diffuser, and wherein the reflector is a windshield of a vehicle;
• and
• a control module configured to
• iteratively adjust a parameter of the first spatial light module to generate the plurality of instances of the beam of light, and
• control operation of the second spatial light modulator to, based on the plurality of instances of the beam of light, display multiple instances of the graphic image on a retina of an eye of a viewer by directing the plurality of instances of the encoded phase hologram of the graphic image toward a reflector or the eye of the viewer.

A method of operating direct-retina holographic projection system, the method comprising:

• receiving a beam of light from a non-image light source at a first spatial light modulator;
• dithering the beam of light at a predetermined frequency to provide a plurality of instances of the beam of light, wherein the dithering comprises iteratively adjusting a parameter of the first spatial light module to generate the plurality of instances of the beam of light;
• receiving the plurality of instances of the beam of light at a second spatial light modulator;
• converting the plurality of instances of the beam of light to a plurality of instances of an encoded phase hologram;
• and
• controlling operation of the second spatial light modulator to, based on the plurality of instances of the beam of light, display multiple instances of an image on a retina of an eye of a viewer by directing the plurality of instances of the encoded phase hologram toward a reflector or the eye of the viewer.