The experimental setup of a proposed glasses-free 3-D theater experience is shown, with the projector in the familiar front position, creating 3-D images. Credit: Optics Express.
the early days of cinema, film producers have used various techniques
to create the illusion of depth – with mixed results. But even with
digital technology, the latest Hollywood blockbusters still rely on
clunky glasses to achieve a convincing 3-D effect.
optics research by a team of South Korean investigators offers the
prospect of glasses-free, 3-D display technology for commercial
theaters. Their new technique, described in a paper published this week in
the Optical Society’s (OSA) open-access journal Optics
Express, can bring this added dimension while using space more
efficiently and at a lower cost than current 3-D projection technology.
has been much progress in the last 10 years in improving the viewers’
experience with 3-D,” notes the team’s lead researcher Byoungho Lee,
professor at the School of Electrical Engineering, Seoul National
University in South Korea. “We want to take it to the next step with a
method that, if validated by further research, might constitute a
simple, compact, and cost-effective approach to producing widely
available 3-D cinema, while also eliminating the need for wearing
is one of the fundamental properties of light; it describes how light
waves vibrate in a particular direction—up and down, side-to-side, or
anywhere in between. Sunlight, for example, vibrates in many directions.
To create modern 3-D effects, movie theaters use linearly or circularly
polarized light. In this technique, two projectors display two
similar images, which are slightly offset, simultaneously on a single
screen. Each projector allows only one state of polarized light to
pass through its lens. By donning the familiar polarized glasses, each
eye perceives only one of the offset images, creating the depth cues
that the brain interprets as three dimensions.
two-projector method, however, is cumbersome, so optical engineers have
developed various single projector methods to achieve similar effects.
The parallax barrier method, for example, succeeds in creating the
illusion of 3-D, but it is cumbersome as well, as it requires a
combination of rear projection video and physical barriers or optics
between the screen and the viewer. Think of these obstructions as the
slats in a venetian blind, which create a 3-D effect by limiting the
image each eye sees. The South Korean team has developed a new way to
achieve the same glasses-free experience while using a single front
projector against a screen.
Actual experimental results demonstrate the promise of a glasses-free 3-D theater experience. Two cars, one red and one blue, are projected onto a screen through a parallax barrier. As the light shines back through the polarizer, two offset images are created, which creates the visual cues that the brain interprets as depth. Credit: Optics Express.
their system, the Venetian blinds’ “slat” effect is achieved by using
polarizers, which stop the passage of light after it reflects off the
screen. To block the necessary portion of light, the researchers added a
specialized coating to the screen known as a quarter-wave retarding
film. This film changes the polarization state of light so it can no
longer pass through the polarizers.
the light passes back either through or between the polarizing slates,
the offset effect is created, producing the depth cues that give a
convincing 3-D effect to the viewer, without the need for glasses.
team’s experimental results reported today show the method can be used
successfully in two types of 3-D displays. The first is the parallax
barrier method, described above, which uses a device placed in front of a
screen enabling each eye to see slightly different, offset images. The
other projection method is integral imaging, which uses a
two-dimensional array of many small lenses or holes to create 3-D
results confirm the feasibility of this approach, and we believe that
this proposed method may be useful for developing the next generation of
a glasses-free projection-type 3-D display for commercial theaters,”
a next step in their research, the team hopes to refine the method, and
apply it to developing other single-projector, frontal methods of 3-D
display, using technologies such as passive polarization-activated lens
arrays and the lenticular lens approach.
their experimental results are promising, it may be several years until
this technology can be effectively deployed in your local movie theater
for you to enjoy without polarizing glasses.
Source: Optical Society of America