| What is the significance of polarizer transmission? |
| Polarizer transmission lets you estimate what will be the lumen loss due to the polarizer. For example, mounting a polarizer with 40% transmission on a 5,000 lumen projector will give output of 2,000 lumen. |
| What is the significance of polarizer extinction? |
| Polarizer extinction is a quantitative measure of its blocking power for the cross (orthogonal) polarization state. Higher extinction means better blocking. |
| Why high extinction is important? |
The fact that polarizers have finite extinction contributes to an image artifact called "ghosting". Ghosting is manifestation of light leakage from a given eye image to the other eye.
Ghosting is a prime quality degradation factor in 3D passive projection displays. It impairs significantly the 3D sensation, and can even ruin it completely in extreme cases. Therefore ghosting reduction is a major design goal in 3D displays. |
| What extinction is more important: that of the projector polarizer or that of the eyewear polarizer? |
| Both are equally important. The overall system performance is determined by the worst polarizer between the two. |
| Can I eliminate ghosting by using very high extinction polarizers in both projector and eyewear? |
| No. There is another contribution to ghosting: screen depolarization. In fact, in typical situations this contribution is dominant. Due to this phenomenon, any increase in polarizer extinction beyond 1000:1 has little effect on the ghosting level. |
What can I do to reduce ghosting? |
1. Choose a screen with best extinction
2. Avoid content with high contrast gradients (black patch adjacent to white). |
| What is better: circular or linear polarization? |
The only advantage of circular polarization is its lack of sensitivity to observer’s head orientation. However, compared to linear polarization it has the following disadvantages:
1. Lower extinction
2. Higher price
3. Color distortions may be noticeable in some cases.
Circular polarization should be considered only in cases where the viewer is moving (like moving chair cinema). |
Advisol Filters
