RealD Cinema

RealD 3D is a digital - polarization system for 3D movies, which, unlike some older method, no two projectors needed. Another advantage of the RealD system is that already existing DLP projectors can be used - but complemented by a projector - intent, audience eyeglasses and special silver-coated screens (see screen).

The RealD 3D system based on an electro -optic modulator, ZScreen called, which was devised by the American inventor Lenny Lipton.

The RealD system is used in Germany in 233 cinemas.

Technology

The technique that uses RealD is similar to the traditional method of 3D projection, the use of linear polarization. In the traditional method, two linearly polarized images are projected onto the same screen, which are polarized inclined by 45 ° and -45 ° relative to the horizontal. The polarizing lenses in the same angles of the audience to ensure that each eye sees only the right image. This type of 3D projection requires two projectors and has the disadvantage that there is ghosting when the viewer tilts the head to the side and thus the angle of the polarization filter of the projector and glasses not match exactly.

RealD but requires only a single projector that alternately uses the right and left image projected and circularly polarized light. An LCD element of the projection lens, the light polarized to the one eye in a clockwise and the other counterclockwise. In the viewer glasses sits a combination of a retardation plate and a polarizing filter. The retardation plate converts the circularly polarized light into linearly polarized light. Different orientations of the wave plates (which are perpendicular to each other and with the horizontal line in each case form an angle of ± 45 ° ) in the lenses ensure that each is only converted into a glass right circularly polarized light into linearly polarized horizontally. In the other glass left-circularly polarized light is converted to horizontally linearly polarized light. Subsequent polarizers on the ocular side of the lenses are aligned both horizontally ( the forward direction ). This ensures that each eye sees only his image, and even if the viewer tilts his head. The very high frame rate of 72 frames per second and eye ensures a flicker-free image. Since the video signal provides only 24 frames per second, is projected in RealD each picture three times to avoid a flicker effect.

Canvas

In order to use the polarization method, a silver-coated canvas is required which reflects the light. In a projection onto a conventional white screen, the polarization of the light is lost because the light is scattered on the surface of the canvas. In general, conventional cinemas, however, are equipped with a white canvas.

The problem of additionally required silver screen can be avoided if instead of the polarization alternating projection of images is used for the left and right eye ( ie is not used RealD ). Through the use of shutter glasses, which ( via infrared signal controlled ) alternately one and then turn the other lens dark, the conventional canvas can be used, but the shutter glasses used here, are more expensive by orders of magnitude. Even when using interference filter technology which eliminates the use of a silver screen.