Eyetap

The EyeTap is a device which "allows the eye itself to function as both a display and a camera". Eyetap devices measure the quantity of light in each of a large number of rays of light that converge into at least one eye of the wearer, and then resynthesize these same rays of light. Ideally each ray of incoming light generates a collinear ray of synthetic light, in a properly calibrated eyetap. The eyetap criteria define how well a practical embodiment matches this ideal condition. Eyetap devices are useful as electric eyeglasses for visual seeing aids.

Stereo eyetaps modify light passing through both eyes, but many research prototypes (for reasons of ease of construction, etc.) only tap one eye. eyetap is also the name of an organization founded by inventor Steve Mann to develop and promote eyetap-related technologies such as wearable computing.

An EyeTap device consists of a light sensor and a light effector (light synthesizer) in perfect alignment. Actually there are three things that are in perfect alignment in a functioning eyetap: (1) the sensor (lightspace analyzer); (2) the effector (lightspace synthesizer); and (3) the eye itself.

Light impinging on the EyeTap sensor, is measured, and used to drive the EyeTap effector, known as an aremac (camera, reversed). Typically, however, there is a processor that sits between the sensor and effector, such that the light gets modified, under computer program control, before it reaches the eye. Light from the surrouding scene can be altered, supplemented, or occluded by the EyeTap before it is transmitted to the eye. This is sometimes referred to as "computer mediated reality".

Using the eyetap as an electric seeing aid, (i.e. wearing it continuously) as one would wear traditional optical eyeglasses, makes lifelong video capture possible. Since many eyetap devices also record EEG (from the ocippital lobe) and interface to other sensors (like ECG), the eyetap provides, in addition to other physiological sensors, a lifelong visual record called a CyborgLog. Such a log file is useful for health monitoring or personal safety, giving rise to the notion of "inverse surveillance" (sousveillance—while surveiller means "to watch from above," sousveiller means "to watch from below"). The general idea is a kind of expansion from the "community watch" neighborhood concept, but features the ability of common people to report on the activities of those "above" them, in positions of civil or military authority and power.

Note that the eyetap is not a display, although the eyetap does typically contain a computer controlled laser light source that can synthesize new matter in the eye (e.g. change a billboard in view of the wearer into a personal display such as email message). Unfortunately a manufacturer of head mounted displays has chosen a very similar name "eyetop" (perhaps to capitalize on the popularity of the eyetap name), and this has resulted in much confusion because people have often (without careful analysis) thought that the eyetap was a display. James Fung has greatly advanced the actual research to the use of an eyetap to display data (using the Reality Window Manager), which runs at around 100 frames per second (more than 3 times faster than NTSC video) for replacement of billboards with Xwindows. Using RWM it is actually therefore possible to use an eyetap as a display, although the original intent of the eyetap was for use as electric eyeglasses.

The EyeTap principle can be applied to other forms of electromagnetic energy such as heat, as shown below:

More generally, EyeTaps can transcode light across various spectral bands, as well as capture, process, and mediate visual experiences into a form most well suited to the unique visual capabilities of each individual wearer. Because the device intercepts rays of light that are collinear with rays passing through the exact center of the eye, when you look a glogger right in the eye, you see what looks like a lens or similar optical assembly that appears to be mounted right in their eye socket:

In fact the iris of the glass lens is mapped exactly to the iris of the eye, which is also the same point where all the rays of laser light pass through on their way to the retina. Optometrist Mel Rapp, of Rapp Optical, is also working on fitting EyeTaps to specific individuals.

External links

• EyeTap device (http://www.eyetap.org/research/eyetap.html) brief description
• eyetap.org (http://www.eyetap.org/)