Virtual retinal displayTM, a scanned photon delivery system

The VRD functional components are illustrated. RGB video drives modulators to impress information on Gaussian beams, which are optically combined to form full-color pixels of luminance and chromaticity determined by appropriate colorimetry. Typically, the pixel stream is fed into a single-mode optical fiber of length sufficient to dislocate the photonics/electronics package from the head worn scanning engine. There, the beam is air propagated to a focus lens, deflected into a raster format synchronized with the video, optically collimated, and combined with the viewer´s visual field to achieve a spatially stabilized virtual image presentation. Multiple image-writing beams may be incorporated to increase the pixel count achieved with a given horizontal line scanner, designed to operate in air at resonant frequencies. Vertical refresh scanners are of sawtooth-driven servo type for progressive line scanning. The writing beam forms a narrow optical exit pupil which may serve as a viewer self-alignment feature in vision screening products such as an ophthalmic perimeter, or may be expanded to meet typical military aviation HMD requirements. A narrow exit pupil is relatively insensitive to a user´s refractive errors or occluding media, making the VRD an inherently superior approach to low vision aiding. An active narrow exit pupil concept is currently under development to optimize VRD image quality and light efficiency