FOURWARD EYETRACKER The dual-Purkinje-image (DPI) Eyetracker, manufactured by Fourward Optical Technologies, Inc., is a research instrument that determines the direction of gaze over a large, two dimensional visual field with great accuracy and without any attachments to the eye. It operates with infrared light which is invisible to the subject and does not interfere with normal vision. The Eyetracker has a pointing accuracy on the order of one minute of arc, and response time on the order of one millisecond. You can attach the Infrared Optometer to allow a continuous measure of eye focus -- producing a 3-D Eyetracker.
The DPI Eyetracker is the finest research instrument of its kind available today. It is compact, easy to use, fast and extremely accurate. At present Fourward offers two Eyetracker models. One is their top-of-the-line Generation 5.5 DPI Eyetracker, and the other is the DPI Eyetracker 1000 (slightly different specifications and a few less options than their 5.5 model). Fourward has installed these eyetrackers all over the world.
Following is a brief description of some of the Eyetracker Options available:
Infrared Optometer
The Optometer is a real-time +/- 10 diopter optometer that attaches to the Fourward Eyetracker and tracks changes in accommodation while the Eyetracker tracks in the x/y axes. The Optometer can be attached to an existing Eyetracker or be provided with new units. The optometer displays continuous accommodation changes on a front-panel meter and an additional analog output BNC. Calibration is provided by the end user.
Stimulus Deflector
The Stimulus Deflector, also called the Stabilizer, is an option that allows the horizontal and vertical rotational outputs of the Eyetracker to be fed back to a pair of x/y galvanometers that are in the optical path. With proper adjustment the "real world" fixation targets can be stabilized at the retina. There is also another option offered to the stabilizer that allows a focus stimulus in the "z" axis for a 3"D system. With the Stimulus Deflector you also have control over spherical correction (focus) and provision for the placement of trial lenses (astigmatic correction).
Scotoma Device
The Scotoma Device is an attachment to the stimulus deflector which allows a scotoma image of any shape to be stabilized on the retina, while the "real world" remains unstabilized. These "scotomas" are created on a glass plate that blocks a portion of the viewing area and simulates retinal pathologies.
Fundus Illumination and Measuring Instrument (FIMI)
The Fundus Illumination and Measuring Instrument (FIMI) option allows real-time binocular viewing of the retina by a white-light source, while a stabilized low-power He-Ne pilot laser beam is stabilized by the operator on the retina.
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