| abstract |
A projection system (12) projects images onto a projection surface (16) in, for example, a computer game head-mounted display (HMD) (208). The light is projected through a spatial light modulator that contains a phase-only image of a Freeform Fourier Lens (14) that is a combination of a Fresnel lens (28), an X-phase grating (30), a Y-phase grating (32), and a radial grating (34). The freeform lens (14) is a condensing freeform lens that causes the gradual shrinking of portions of the laser-projected image, decreasing the perceived pixel pitch in at least one foveal area on the projection surface compared to a non-modulated laser image. The center positions of the Fresnel lens (28) and radial grating (34) can be changed in the X and Y axes, moving the condensed foveal areas in accordance with eye tracking of the user (16). |