3D TV

RealD Cinema is a digital stereoscopic projection technology.

It is the world's most widely used technology for watching 3D movies in theatres and is the cheapest to install and maintain. It requires only one projector, unlike older film-based stereoscopic 3D projection technology. A high-resolution, digital cinema grade video projector is used.

RealD was founded in 2003 by Michael V. Lewis and Joshua Greer. Between 2005 and 2007 the company purchased Stereographics Inc. and optical components technology company ColorLink, a provider of rear-projection television (RPTV) equipment, polarizing film and optical technologies including technologies for the US Military. RealD developed its acquired technology to create its 3D cinema systems.

RealD supplies 3D technology to customers including Fortune 500 companies, theme parks, education centers, and for medical research and procedures.

Technology

RealD 3D cinema technology uses circularly polarized light to produce stereoscopic image projection. Circular polarization technology has the advantage over linear polarization methods in that viewers are able to tilt their head and look about the theater naturally without a disturbing loss of 3D perception, whereas linear polarization projection requires viewers to keep their head orientation aligned within a narrow range of tilt for effective 3D perception; otherwise they may see double or darkened images.

The projector alternately projects right-eye frames and left-eye frames 144 times per second. It circularly polarizes these frames, clockwise for the right eye and counterclockwise for the left eye. A push-pull electro-optical liquid crystal modulator called a ZScreen is placed immediately in front of the projector lens to switch polarization. The audience wears spectacles with oppositely circularly polarized lenses to ensure each eye sees only its designated frame, even if the head is tilted. In RealD Cinema, each frame is projected three times to reduce flicker, a system called triple flash. The source video is usually produced at 24 frames per second per eye (total 48 frames/s), which may result in subtle ghosting and stuttering on horizontal camera movements. A silver screen is used to maintain the light polarization upon reflection and to reduce reflection loss to counter the inherent losses by the polarization filters. The result is a 3D picture that seems to extend behind and in front of the screen itself.

Viewing comfort

3D systems for movies using polarized light cause a loss of screen brightness due to the inherent filter absorption. The polarization filter in front of the projector blocks half of the projecting light, reducing screen brightness. However, as half of all other ambient and reflected light in the theater is also reduced by the viewing lenses, the perceived contrast does not suffer excessively. The overall effect is that of wearing a pair of slightly darkened glasses in a standard movie theater, which could be compensated by using brighter projector lamps.

One complaint with many 3D display systems is that some viewers may feel nauseated or experience a headache.[8][9] This effect is more likely with rapid cuts between scenes with very different depth, which directors and editors of 3D movies generally try to avoid.