Introduction
©
2016-2017 SR Research Ltd.
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1 Introduction
This section introduces the technical capabilities and supporting
documentation for the EyeLink Portable Duo eye tracker. The EyeLink Portable
Duo eye tracker is intended for researchers who require high-quality eye
tracking data both in and out of the laboratory. The eye tracker illuminates the
participant’s face and eyes with invisible near-infrared light; an internal USB
camera acquires up to 2000 images per second. The camera images are
processed by the attached Host PC to identify landmarks on the eyes and face,
allowing measurement of the participant’s gaze location.
The EyeLink Portable Duo, with IEC 60601-1 medical certification, meets the
requirements for use in medical environments (e.g., more stringent electrical
isolation, easier cleaning, etc.). These goals are met by adopting a unitary
design with a simple enclosure, and with no exposed parts such as lenses or
illuminator arrays. In addition to providing electrical isolation from internal
parts and cable entry protection, this enclosure also provides low thermal
resistance to keep the internal parts (especially the sensor) cool while radiating
sufficient heat to keep its temperature within safety requirements. The compact
design of the eye tracking unit makes the EyeLink Portable Duo easier to
transport and simpler to set up compared to other models of EyeLink eye
trackers.
Another unique design feature of the EyeLink Portable Duo is its built-in
capability for dual use as either a high-accuracy head-stabilized eye tracker or
as a head free-to-move remote eye tracker. By adopting a compact, yet highly
sensitive lens and illumination module, the EyeLink Portable Duo can operate
in two distinct modes with the same set of eye tracking hardware (i.e., no
change of lens or illumination module is required). The head-stabilized and
remote modes can be easily accessed through the Host Application, and share
the same application programming interface (API) and EyeLink Data File (EDF)
output. This allows experimenters to seamlessly switch between data collection
and analysis modes that best suit their particular experimental paradigm or to
accommodate different participant populations.
The EyeLink Portable Duo operates at an extremely low noise level, which is
required for accurate gaze-contingent paradigms, and which offers researchers
the high levels of data quality that careful research demands. EyeLink systems
are the only modern commercial eye-tracking equipment to run on a real-time
operating system; running on such an operating system ensures low temporal
variability and near-instant access to eye data measures. Compared to other
remote systems on the market, the EyeLink Portable Duo provides high-
accuracy eye tracking data with extremely low noise.