Light-efficient augmented reality 3D display using highly transparent retro-reflective screen.

We propose and demonstrate a light-efficient 3D display using a highly transparent desktop-sized augmented reality screen. The display consists of a specially designed transparent retro-reflective screen and a pair of low-power pico-projectors positioned close to the viewer's eyes to provide stereo views. The transfer screen is an optically clear sheet partially patterned with retro-reflective microspheres for high optical gain. The retro-reflective material buried in the screen reflects incident light back towards the projectors with a narrow scattering angle and facilitates the viewer to perceive a very bright content. The tabletop prototype mainly consists of an in-house fabricated large augmented reality (AR) screen (60  cm×40  cm) and a pair of laser-scanning 30 lumen pico-projectors. The display is tested for different viewing configurations, and different display parameters, such as retro-reflective coefficient, eye-box size, polarization maintainability, stereo crosstalk, and brightness, are examined. The AR prototype display provides 75% optical transparency, exceptional brightness (up to 1000  cd/m2 when viewed through beam splitters and 350  cd/m2 with bare eyes), and negligible crosstalk in 3D mode (<5% and <1% when viewed through beam splitters and polarizers, respectively) for the working distance of up to 2 m.