Dolby 3D

Functional principle of color separation

Dolby 3D (formerly known as Dolby 3D Digital Cinema ) is a 3D digital projection process from Dolby Laboratories, Inc. One advantage over polarization processes is that no special silver screen is required, which significantly reduces costs for cinema operators. If the viewer tilts his head, there are no disadvantages for the 3D effect that exist with linear polarization.

Since 2012, a 3D TV display technology without 3D glasses (autostereoscopic) has been developed with the same name in collaboration with Philips researchers .

technology

A special filter is installed in the projector , between the lamp housing and the projection unit, which can also be removed for normal 2-D playback. The spectators wear special passive glasses for the 3-D effect . These glasses are more expensive than polarizing filter glasses and are therefore usually rented out by cinemas, cleaned after use and used several times. The technology for the 3-D effect is called interference filter technology and was licensed by Dolby from the German company Infitec GmbH (acronym for interference filter technology ). As with the polarization method, Dolby 3D also offers the option of using two projectors with a permanently installed filter or of operating one projector at 144 Hz. In the latter case, a filter wheel (similar to the color wheel in single-chip DLP projectors) is used instead of a fixed filter, which rotates at 72 revolutions per second. This alternately projects images for the right and left eyes.

Interference filter technology

The light filter separates the light of the primary colors red, green and blue into two different wavelength ranges . Precise interference filters in the glasses ensure that each eye can only see the corresponding areas of the spectrum. The differences in color perception for the left and right eyes resulting from the deviations in the basic colors are corrected in the projector prior to (digital) projection so that an identical color impression is created in both eyes through metamerism . Due to the angular dependence of interference filters, the Dolby 3D filter must be placed inside the projector, at a point between the lamp and the projection unit. This makes it difficult to retrofit home cinema projectors and, in addition to the necessary color correction, is the main reason that this technology is rarely used in the home.