Fiber-scanning based ultra-compact near-eye display with a narrow-beam waveguide

For ultra-compact near-eye display, waveguides provide a small form factor because they are thin shape plate, but projectors are too large due to the imaging sources, which results in bulky near-eye displays. Recent advances in fiber-scanning technology can overcome this limitation. Fiber-scasnning projectors produce an image by vibrating an optical fiber, and they can be small because only thin fibers and actuators are required. However, uneven brightness occurs when augmented reality images from the fiber-scanning projector are displayed using a conventional waveguide. In this paper, we propose a novel waveguide that duplicates a narrow beam by multiple reflections of a pre duplicator, which is a flat-plate-shaped optics with mirror and half-mirror surfaces. The proposed waveguide enables uniform luminance distribution with a fiber-scanning projector by providing narrow duplication intervals. We experimentally confirmed that the contrast of luminance unevenness decreased from 0.60 to 0.15 with our waveguide. Our fiber scanning projector size is less than 0.03 cc and can be placed on the temples of eyeglasses, which is impossible with general projectors of about 5 cc. Therefore, the proposed waveguide and fiber scanning projector enable the realization of eyeglasses shape near-eye displays.