Bionic Contact Lens May Lead to Overlay Displays

pfman writes "A University of Washington researcher has developed a contact lens including circuitry and a matrix of LEDs. Although not yet a working prototype, this may be a foundation for terminator/robocop style overlay displays in which computer graphics could be superimposed on your normal vision. 'Building the lenses was a challenge because materials that are safe for use in the body, such as the flexible organic materials used in contact lenses, are delicate. Manufacturing electrical circuits, however, involves inorganic materials, scorching temperatures and toxic chemicals. Researchers built the circuits from layers of metal only a few nanometers thick, about one thousandth the width of a human hair, and constructed light-emitting diodes one third of a millimeter across.'" Kotaku notes that this has some obvious gaming implications.

Re:Um, what?

[debianlinux]

I believe TFA was referring to placing peripheral components such as wireless reception on the part of the lens that is not used by the eye for viewing.

Re:Um, what?

[JesseL]

You're confusing two different phenomena. The blind spot from the optic nerve is not in the center of the eye. The reason for the astronomers trick is due to the distribution of rods (brightness receptors) and cones (color rectors) in the eye. There are more cones at the center of the retina, but the more sensitive rods are distributed more peripherally.

Re:Um, what?

[Jott42]

The optic nerve does not exit at the dead center of the eye; the blind spot, where it connects, is to the side of the center. But the center of the eye has the highest concentration of cones, which gives us colour vision. To the sides the rods are more common, these have better sensitivity, but are only registering the amount of illumination, not the colour. Thus an astronomer who is searching for faint objects in the sky is better of looking to the side of the object, using the rods of the retina, than trying to see the objects in colour with the cones, as they are less sensitive to light.

Holography is required

[Blancmange]

The lens system of the eye (cornea, crystalline lens and the overall air/liquid interface) is a kind of parallel optical computer that applies a function to both the angle of incidence and the location of incidence in order that light coming from points on a roughly planar region in the scene map neatly to points on the retina. Interestingly, if you look through a pinhole, you force the angles of incidence and the location of incidence to be correlated and the lens system of your eye becomes a spatial modulator - You can see the imperfections on the cornea, the shape of any cataracts you have and even the outline and surface details of the adjustable lens if it's a bit too small to span the pupil.

Anyway, the lens system is mainly geared for mapping angle of incidence to points on the retina. The location of incidence part is there so more than one point on the surface of your eye can contribute to gathering light. The parallax errors of the set of extra points is what causes the lack of focus for points outside the current scene focal plane.

Conventional helmet mounted displays work by using lenses to make their small-and-near displays appear big-and-far. In other words, every pixel in the display reaches your eye as a plane wave whose direction dictates the point on your retina that gets illuminated. The effect is ruined when the optics are bumped even slightly, so these HMDs are a real source of eyestrain. Just your eye moving around is enough to screw up the focus on units with very small display elements.

Retinal projection systems work by using detailed knowledge of the lens system of your eye to beam pixels at different parts of the cornea in a way that sort of bypasses the natural function of the lens system. The projector is far too close for the eye to focus. If you could, you'd find the projector nothing more than a tiny light that occupies only a small point of your vision. RPs work by being way out of focus (so they appear large in your field of vision) and achieving their sharpness by using the parallax errors as a feature - something that can only be done with small, tightly controlled laser beams.

A contact lens display system would require the ability to emit thousands of precisely aimed beams or plane waves. At the cornea, the location of the emitters is almost irrelevant. If they emitted spherical waves (as LEDs tend to do), the patch of light from each emitter would span a large part of the entire retina. The 7x8 display in TFA would appear as a 7x8 Photoshop image subject to something like a Gaussian blur of a radius close to the size of the entire image (but on a much larger canvas).

That's where holography comes in. To avoid needing detailed knowledge of the eye, the holographic system uses millions of simple emitters programmed to effectively generate the required plane waves through constructive and destructive interference. No extra lens system is required.

The computational power might be a wee challenge, though. Otherwise the holographic contact lens system is elegant in its simplicity.