EyeLink II® Tracking
Modes |
| Mode |
Sample Rate |
Avg. Delay
(Filter off/normal/ high) |
Noise (RMS) |
Stability |
| EyeLink Pupil-Only |
250 Hz |
6 ms / 10 ms |
< 0.01° |
Affected by headband slip and vibration
|
| EyeLink II Pupil-Only |
500 Hz |
3 ms / 5 ms / 7ms |
< 0.01° |
Affected by headband slip and vibration
|
| EyeLink II Pupil- CR |
250 Hz |
6 ms / 10 ms / 14 ms |
< 0.022° |
Good rejection of slip and vibration
|
| Operational/Functional
Specifications |
| Feature |
EyeLink II |
EyeLink |
| Image processing |
Fully digital |
Hybrid analog-digital |
| Pupil tracking |
Hyperacuity |
Hyperacuity |
| Corneal reflection
tracking |
Hyperacuity, ultra
low noise |
None |
| Sampling rate |
250 or 500 Hz |
250 Hz |
| Average data
transit delay |
250 Hz, filter off
= 6 ms
250 Hz, filter on = 10 ms
500 Hz, filter off = 3 ms
500 Hz, filter on = 5 ms |
filter off = 6 ms
filter on = 10 ms |
| Resolution (Gaze) |
Noise limited to
<0.01° (pupil), <0.022° (pupil-CR) |
Noise limited to
< 0.01° |
| Velocity noise |
< 3°/sec |
<3°/sec |
| Gaze position
accuracy |
<0.5° average |
<0.5° average |
| Pupil size: resolution and noise |
0.1% of diameter (~0.004mm), Noise
level < 0.01mm |
0.1% of diameter (~0.004mm), Noise
level < 0.01mm |
| Heuristic Filtering |
Average velocity-matched
filter |
Nearest-neighbor heuristic
filter |
| Eye tracking range |
±30° horizontal, ±20°
vertical in pupil only mode |
±30° horizontal, ±20° vertical (pupil
only) |
| Gaze tracking
range |
±20° horizontal,
±18° vertical |
±20° horizontal, ±18°
vertical |
| Head tracking range |
40-140 cm (standard setup),~300 cm
(special markers) |
40-140 cm (standard setup),~300 cm
(special markers) |
| Head rotation compensation range
|
±15° for best accuracy,
±30° conditional on gaze angle. |
±15° for best accuracy, ±30° conditional
on display location |
| Built-in calibration,
validation |
Calibration / validation
using Pupil or Pupil-Corneal |
Calibration and validation
using Pupil-only |
| Operating environment |
Tolerates significant
indirect IR, CR mode can reject more slippage than pupil only mode. |
Required IR-free environment,
physical stability |
| Subject compatibility |
Most eyeglasses and
contact lenses in pupil only mode: less compatibility in CR mode. |
Most eyeglasses and
contact lenses |
| Data file |
EDF |
EDF, direct to disk |
| EDF file and
link Data Types |
Eye position, HREF
position, gaze position, pupil size, buttons, messages, digital inputs. |
Eye position, HREF
position, gaze position, pupil size, buttons, messages |
| On-line eye movement
analysis |
Saccades,
fixations, blinks, fixation updates |
Saccades, fixations,
blinks, fixation updates |
| Real-time operator
feedback |
Eye
position cursor during calibration, validation, and recording. Camera
images and tracking status. |
Gaze cursor during
recording and validation, eye position cursor during calibration,
camera images. |
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|
| Physical Specifications |
| Feature |
EyeLink II |
EyeLink |
| EyeLink II Card |
Half-length PCI (6.8"/176mm) |
Full-length ISA (13.5"/343mm) |
| Headband |
Headband Padded with height and size
adjustments
|
Leather-padded, height and size adjustments |
| Headband weight |
~420 grams, low center of gravity |
~600 grams |
| Headband cable length |
4.2meters |
5 meters |
| Eye camera distance |
40 to 80 mm |
40 to 80 mm |
| Binocular tracking |
Standard |
Standard |
| Eye Illumination |
925 nm IR (pupil) 880 nm IR (CR),
IEC-825 Class 1, <1.2 mW/cm2 |
925 nm IR, IEC-825 Class 1, <1.2
mW/cm2 |
| Display Markers |
880 nm IR, IEC-825 Class 1 |
925 nm IR, IEC-825 Class 1 |
| Ethernet Link |
TCP/IP or raw, 10BASE-T, built into
EyeLink II card |
TCP/IP or raw, 10BASE-2 or 10BASE-T,
external card with packet driver |
| Response box support |
USB or digital |
Digital |
| Analog output |
Optional PCI card |
Optional ISA or PCI card |
| Digital Control |
Configurable |
Configurable |
| Display Operating system API |
Windows ( 2000, XP Professional Service Pack 1), MS-DOS,
Macintosh OSX, Linux |
MS-DOS, Macintosh, Windows
(95 and 98) |
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