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Express Eye - Eye Tracker

high precision, low cost eye movement measurement

Document Index:

• Introduction
• Description
• Technical Data
• Applications

The first scientific eye movement measurements in this group were made 15 years ago with an instrument redesigned after Gautier (Electroencephal.Clin.Neurophys. 39 (1975); 285-291) using infrared light reflection of the eyeball.

Express Eye uses basically the same measurement principle that has proven to be very reliable, precise and able to deliver data with very high time resolution.

This historical device is rebuilt with todays high quality mechanics, an up to date electronic signal processor (largely eliminating disturbances from background light). It is a reliable, easy to use, stand alone eye movement recording system.

Note: Express Eye is optionally available for automatic saccade analysis with included head mounted target generator and a handheld micro-controller. This allows a quick and easy test of a subject's quality of fixation, reflexive gaze control and ability to produce voluntaty saccades and to test saccadic reaction times.

Description

A lightweight head band holds a detector unit in front of the eye (at about 2 cm distance).

The size of the head band is adjustable in two dimensions to ensure optimum fit, even for children.

The detector unit can be moved in 3 dimensions for easy adjustment in front of the eye - the guarantee for a good and linear signal.

An additional horizontal fine adjustment makes sure that the optimum position can be found quickly and easily. The manual describes how you can optimally adjust the detector unit for each subject in less than a minute.

Technical Data

• measured horizontal position of one or two eyes
  (vertical measurement under development, please ask for details)

• measurement principle: IROG
  

• temporal resolution: 1 millisecond
  

• spatial resolution: 0.1 deg
  resolution is better than 0.1 degrees within the full linear range of +/- 15 degrees or even higher if you increase the amplification on cost of the range.

• field of view: +/- 15 degrees
  the infared light emitter is positioned below the eye, the detectors are mounted on the left and right of the eye leaving a field of free view of about +/- 15 degrees.

• linearity: 95% within +/- 4 degrees, 90% within +/- 15 degrees

• data output
  Data is output in the standard version via analog line.
  Optionally it can be sent as digitized 10 bit data via serial line at 38400 Baud data rate.

address:
  Optomotor Laboratory
  c/o B.B.L. Fischer
  Tivolistraße 11
  D-79104 Freiburg
  Germany