3D Polatization Modulator (active-passive projection)
Hybrid active-passive 3D technology (Polarization modulator)
It is possible to combine the advantages of the active and the passive system. This method makes possible to realize passive projection by the help of only one projector.
3D projection based on Polarization modulator
The key element of the hybrid active=passive system is a Polarization modulator placed in front of the projector. The modulator is electronically synchronized with the projector. The 3D projector works in active mode alternating between left and right eye image projection. The modulator is able to change the polarization of passing through light. During the left eye period modulator polarize in one plane and for the right eye period it switched to opposite plane.
Passive 3D glasses are sufficient
Simple lightweight passive glasses polarization glasses are fully sufficient for the use with this system. The glasses use the filters compatible wit the used modulator (linear or circular). Base don this each eye seethe proper view.
Advantages of hybrid passive-active technology
The firs advantage of passive-active technology is the use of only one projector. You can save money for the second projector. Passive-active technology does not require complex dual projector alignment – perfect left and right image overlap is always achieved. Switch between 2D and 3D mode is simple. In addition standard simple passive glasses are sufficient. Passive glasses do not require any batteries, nor maintains and they are usually very mechanically robust. The modulator is suitable for both small 3D projection systems as well as for big digital 3D cinemas.
Overview of 3D stereoscopic technologies:
| technology | color informations | rozlišení obrazu | projection | monitors / tv | num. of viewers | 3D cinema expenses [price / operating costs] |
| Active 3D | full | high | yes (2) | yes (3) | limited (4) | high / high |
| Passive 3D | full | high | yes | yes | high | high / low (5) |
| 3D Polarization Modulator | full | high | yes | no | high | middle / low |
| 3D Auto-Stereoscopic Monitors | full (1) | low | no | yes | low | - |
| 3D Anaglyph | very bad | middle | yes | yes | high | low / low |
(2) - active 3D is not suitable for large 3D cinemas. Active 3D glasses are expensive and servising is also hard job (repairing, changing/recharging bateries).
(3) - active 3D displays (3D TV, computer 3D flat panels) provide the highest 3D quality from all 3D screens.
(4) - number of viewers is limited by expensive 3D glasses and the wireless signal range.
(5) - 3D Modulator is currently the best 3D technology for all modern 3D digital cinemas.