Рубрика:
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of these into a functional system on the top of an unconventional substrate, such as
the polymer that a contact lens is made from.
The production of such contact lenses involves three main steps. First, a plastic
template is created as a mould for micron sized metal contacts: this mould, on which
the metal contacts are then coated, is created by digging guidelines into a plastic
(PET) sheet using a photolithography process. Then the self-assembly step is quite
simple: the plastic template is dipped into a special solution with some
microelectronics components; thanks to capillary forces, the components then bind
with the plastic templates in the desired location. Finally, the surface is encapsulated
with a biocompatible material and pressed using a heated aluminum mould which
imparts a permanent curvature on it, creating the contact lens. In the near future, then,
should we expect to be able to wear a super contact lens wirelessly coupled with our
mobile phone, similarly to a Bluetooth headset? Well, there are still a number of
challenges to overcome before this scenario becomes reality.
First of all, a high resolution display still needs to be embedded in the contact
lens. This new technique is suitable for this purpose but "we are still at the beginning
of this path," admits Parviz, "even if our manufacturing technique in principle allows
for integration of a large number of pixels." There are also other technical issues to
solve; most importantly, such contact lenses are likely to be restricted to display just
transparent overlaying images. The reason is that we still cannot selectively block
light from the scene to create an opaque overlay. As Stayman explains, "the lens is
located, quite literally, at the pupil plane of the imaging system and overlaying
images so close to the center of the eye would only change the optical response —
i.e. blurring of the scene," like having a micro-spotlight just in front of your eye! So
will it ever be possible to show opaque images on the contact lens? Stayman believes
that "we could control the transparency of the entire contact lens," modifying the
contrast between the overlaying image and the real world. Almost like turning down
the lights a little bit. This would allow our eye to better distinguish the virtual objects
displayed on the lens, switching the focus from the real scene on the background to
the virtual annotation on the foreground.
Finally, the most intriguing challenge is to understand how to deal with the
constant movements of our eyes. "When we look at something we are constantly
scanning the scene for content, with our eyes darting from area to area; this is
because we use the fovea — the high resolution portion of our retina — for close
inspection of scene content," says Stayman. "The contact lens will move with the eye.
Thus to keep a virtual object or annotation fixed within a scene, the image displayed
on the contact lens must be moved in a direction to compensate for the eyes motions.
This would require some form of eye tracking device — potentially also in the
contact lens itself. Such a tracking system would need to be quite fast and accurate
for virtual objects to appear stationary." Considering these and other issues, it is still
not completely clear how these contact lenses will be converted into fully working
devices able to provide a good platform for Augmented Reality. Thanks to Parviz and
his collaborators’ work, nonetheless, the day when we can simply blink and see all
kinds of useful information popping up in front of our eyes might not be so far away.
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