Dear readers, a 2-D television may not be a new thing for us. But obviously, a 3D television may be new. Now Microsoft's Applied Science Group has demonstrated a new type of lens to be used in television screens, which allows viewers to see images in 3D without the need to wear special glasses.i.e., glasses-free 3-D displays.
The lens, thinner at the bottom than at the top, steers light to a viewer's eyes by switching light-emitting diodes along its bottom edge on and off. Since the lens is thin, it can be incorporated into a standard liquid crystal display (LCD), replacing the traditional backlight; light from the lens shines through the liquid crystals to project the images to viewers.
The 3D display uses a camera to track viewers so that it knows where to steer the light; the idea isn't new, but the required CPU power is now affordable and small enough to pull it off on a large scale.
The design of Microsoft's wedge lens bypasses this problem, as the light is traveling within the lens and not in the air (the focal point is thus the flat surface of the wedge), minimizing the distance between the projector and the screen.
The LEDs control the position and angle of the light as it enters the bottom edge of the lens and, as a result, the direction the light comes out. The viewer-tracking cameras, meanwhile, collect light traveling the other way through the lens.
The system's viewing angle is about 20°, but Microsoft hopes to tweak the lens design and increase it to 40°. That would be an improvement, but 40° still isn't that hot.
Picture quality is limited by the screen's refresh rate, and so Microsoft is pushing display manufacturers to make faster LCDs. Separately, the company is looking into how the lens can be used as the backlight of a laptop that can project images to either one person or to multiple people.
Coupled with a backlight, this makes it possible to present different images to different viewers, or to create a stereoscopic (3-D) effect by showing different images to a person's left and right eye.
Microsoft's prototype display can deliver 3-D video to two viewers at the same time (one video for each individual eye), regardless of where they are positioned. It can also show ordinary 2-D video to up to four people at the same time (one video for each person).
The 3-D display uses a camera to track viewers which enables it to steer light toward them. Microsoft's wedge lens is about 11 millimeters thick at its top, tapering down to about six millimeters at the bottom.
A traditional lens in a projector sits between a point of light and its focal point - the spot where the light is focused. This is why viewer-tracking 3-D systems are usually so bulky.