Circular polarization filters work along the same principles as linear polarizers. The difference between the two is as follows: In linear polarizers the light waves are polarized such that they all oscillate within a single plain. Circular polarizers, however, align the light waves to rotate either clock-wise or counter clock-wise – comparable to the shape of a corkscrew as they move towards and from the projection screen. Analogously, the glasses worn by the spectator have the respective orientation.

The biggest advantage of circular prolarizers over linear polarizers is that even if spectators tilt their heads completely one can guarantee very good separation of channels. The 3D experience is not compromised.

As always when polarizers are used, some of the light of the projector is blocked from reaching the screen. Thus these filters always reduce the brightness of the projection. In general the following holds: The higher the degree of the transmission of the polarizer, the brighter the projection of the picture. Leveraging coated filters is advantageous – they not only improve transmission but also help conserve the longevity of the projector lamps.

Advantages of circular polarization filters:

• Best possible separation of channels, even if spectators tilgt their heads, move around etc.
  
• Very good results, specifically when using high transmission polarization filters.
  
  Disadvantages of circular polarization filters:
  
  
  
  • More costly than linear polarizers
    
  • Significant loss of brightness when using low quality filters with low transmission
    
  • A non-depolarizing silver screen is required for front projection. In other words, the screen must not change the polarization of the reflected light.
    
  • For rear projection screens or rear projection foils one also has to use non-depolarizing material