VAC-reduced naked-eye stereoscopic display with directional backlight and layered display

We propose a naked-eye binocular stereoscopic display that simultaneously provides binocular parallax and multiple focal planes. By combining a layered transmissive display with a directional backlight, the proposed system enables glasses-free three-dimensional presentation while mitigating the vergence–accommodation conflict inherent in conventional binocular stereoscopic displays. Binocular disparity is presented by forming discrete viewing zones using a directional backlight, while multiple focal planes are generated by stacking display layers along the depth direction. In addition, we introduce a directional backlight based on a retroreflective configuration together with a return-path-only modulation scheme using vertical-alignment liquid-crystal panels. This approach enables spatially selective light delivery to the intended viewpoints and suppresses unintended double modulation caused by the retroreflective light path, thereby helping to preserve image quality in a layered display configuration. A prototype system was constructed to validate the proposed concept. Experimental observations confirmed that correct left- and right-eye images are observed at the intended viewpoints and that images are selectively formed at focal planes corresponding to the physical depths of the display layers. These results demonstrate the feasibility of a multiplane naked-eye binocular stereoscopic display based on the proposed architecture. The practical limitations of the system, including viewing area, field of view, optical efficiency, and the number of display layers, are discussed, indicating that a moderate number of focal planes provides a reasonable balance between visual comfort and system complexity.