Passive 3D display systems

Barco has developed very high-quality passive stereo based on the principle of light polarization. The viewer wears a pair of glasses containing two oppositely polarized filters -one for the left and one for the right eye. The light from each of two projected images is polarized and can only pass through its corresponding filter.

With a single projector

The projector alternates the left eye information with the right eye information at double refresh rate.
A 'Z-screen' in front of the projector's lenses alternates the polarization of the projected image in such a way that the image of each eye will pass through the corresponding polarizing filter of the pair of passive stereo glasses.

With a CRT projector

When using CRT projection a "fast phosphor" green CRT is needed to obtain the required high refresh rate. Barco CRT projectors such as the BarcoReality 908, BarcoReality 909 and BarcoReality 912 can be delivered with this option already installed.

With a DLP™ projector

The Zscreen for a DLP™ (Digital Light Processing™) projector such as the Barco Galaxy is smaller because it must cover only one lens, while a CRT projector has three lenses.

LCD projectors cannot operate at a high enough vertical refresh rate to produce a high-quality stereo display with a single projector (at least 96Hz is recommended)

With two projectors

One projector displays the left eye information, the other displays the right eye information, both at standard refresh rate.
A polarizing filter mounted in the optical light path of each projector ensures that the correct information passes though its corresponding filter in the pair of passive stereo glasses.

This two-projector approach has the added value of providing higher brightness.

With two CRT pojectors

Although weaker in light output CRT projectors allow for the highest resolution large screen images, with unprecedented visual fidelity.
Barco CRT projectors offer a motorized polarization screen as an option for stereoscopic projection, whereby the filter can be rotated away from the lens for standard non-stereoscopic projection.

With two DLP™ PROJECTORS

In high ambient light conditions or for very large screen applications, this solution is optimal.
Barco offers a range of high quality DLP™ (Digital Light Processing™) projectors with light output from 5,000 to 25,000 ANSI lumen. For stereoscopic use however "Stereo lumen" - which equals less than half the ANSI lumen value - is the realistic measurement of brightness.

With two LCD projectors

Barco LCD projectors are internally polarized to its corresponding left and right eye information, eliminating the requirement for external filters. With Barco's internal polarization 70% of the original light output is maintained, making this technology the most efficient method available to obtain high stereo lumen brightness levels.

Linear & circular light polarization

A light wave rotates in any direction. The specific orientation at any given moment determines the polarization of a light wave. By passing non-polarized light through a polarizer, only one of its orientations emerges.

By organizing the polarization oppositely for the left and right eye we can direct different information to the left and right eye, thus creating depth perception. As the human eye itself is largely insensitive to polarization, changing the orientation of polarized light alone does not change what we see.

Linear polarization

If light is polarized in a single direction (north/south, east/west, or even oriented diagonally), it is defined as linear polarization. When one changes the orientation of linear-polarized glasses by tilting his or her head, so that the resulting orientation of polarization does not match that of the polarization filter mounted on a projector, there will be a loss of stereo information as perceived by the viewer.

Nevertheless, linear polarization is a cost-effective technology that can produce excellent image separation between the left and right eye, for stereoscopic applications whereby head tilting is limited.

Linear-polarized Barco glasses are matched to linear-polarized Barco projectors, and they offer an excellent quality-to-price value for stereo viewing with large audiences.

Circular polarization

With circular polarization, the viewer can tilt his head and change his viewing angle relative to the stereoscopic projection display, because the light is not polarized in a single direction.

As this high-end technology demands greater precision and requires a tighter match between the polarizing filters in the light path of the projectors and those in the glasses, the use of Barco high-quality circular eyewear is recommended.

Easy to use and comfortable to wear, polarized passive stereo eyewear have no active components and are thus very affordable for large audiences.