in the field of view is interpreted by the visual cortex as having a depth component, due to a relative difference in signal timings between the two eyes. Prismatic glasses make cross-viewing easier as well as over/under-viewing possible, examples include the KMQ viewer. Volumetric display Volumetric displays use some physical mechanism to display points of light within a volume. Such displays use voxels instead of pixels. Volumetric displays include multiplanar displays, which have multiple display planes stacked up, and rotating panel displays, where a rotating panel sweeps out a volume. Other technologies have been developed to project light dots in the air above a device. An infrared laser is focused on the destination in space, generating a small bubble of plasma which emits visible light. Light field display A light field display tries to recreate a "light field" on the surface of the display. In contrast to a 2D display which shows a distinct color on each pixel, a light field display shows a distinct color on each pixel for each direction that the light ray emits to. This way, eyes from different positions will see different pictures on the display, creating parallax and thus creating a sense of 3D. A light field display is like a glass window, people see 3D objects behind the glass, despite that all light rays they see come from (through) the glass. Holographic displays Holographic display is a display technology that has the ability to provide all four eye mechanisms: binocular disparity, motion parallax, accommodation and convergence. The 3D objects can be viewed without wearing any special glasses and no visual fatigue will be caused to human eyes. In 2013, a Silicon valley Company LEIA Inc started manufacturing holographic displays well suited for mobile devices (watches, smartphones or tablets) using a multi-directional backlight and allowing a wide full-parallax angle view to see 3D content without the need of glasses. Their first product was part of a mobile phone (Red Hydrogen One) and later on in their own Android tablet. Integral imaging Integral imaging is an autostereoscopic or multiscopic 3D display, meaning that it displays a 3D image without the use of special glasses on the part of the viewer. It achieves this by placing an array of microlenses (similar to a lenticular lens) in front of the image, where each lens looks different depending on viewing angle. Thus rather than displaying a 2D image