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| Q:
When do I need polarized 3-D glasses (light gray lenses) instead of the
red/blue (anaglyph) ones? |
A: Most two-lens 3-D
projection systems for both slides & movies use the full-color polarized
method. Almost anything printed on a page, or displayed on a computer monitor,
with red/blue or red/green color fringing uses anaglyph
(red/blue) 3-D glasses. |
| Q: How does
polarization work? |
A: The principle of polarization
of light for separation of stereoscopic images was proposed in 1891 by
J. Anderton. The polarizing filters have a molecular structure that is
like an invisible picket fence, with all of the pickets going in one direction.
When a second identical polarizer is crossed at 90° to the first polarizer,
the light gray turns a very dark blue or purple, effectively canceling
most of the light transmission. If separate right & left images are
projected through two polarizers, each at 90° to each other, onto a
non-depolarizing silver screen, and then viewed through 3-D glasses which
match the projection filters, each eye sees the image intended for it,
while the image for the other eye is dark. Your brain does the rest, and
converts the separate images into a combined 3-D one. |
| Q: What are
the polarization angles of your 3-D glasses? |
A: At 45° & 135° (which
are 90° to each other). This has been the standard since the early
1940's. The material itself is a linear polarizer, 30% transmission, either
.010" or .030" thickness, depending on the glasses style. |
| Q: Do I really
need a silver screen? |
A: Yes!!! A white or beaded screen
will depolarize the light, and you will see a flat double image
- even with 3-D glasses on. |
