SR Research EyeLink 1000 Installation Manual page 66

Mounting Bar to place the Camera Head on, and which side to place the Illuminator. The
general considerations below apply to any mount or MRI eye tracking environment.
For most purposes, placing the Camera Head on the left side of the mounting bar
when viewed from behind (right side when viewed looking into the camera is a
good position to start with. This has the camera centrally viewing the eye(s) and
Depending upon your tracking situation, there are a few considerations in optimal placement
of these components:
The Camera Head always needs an unobstructed line-of-sight view to the eye(s) to be
tracked.
Which eye will be tracked – the dominant eye? Left or right? Having the Camera Head
on the same side as the eye-to-be-tracked may allow one to avoid obstructions.
Is binocular tracking required? For binocular tracking a more centered camera view is
desirable.
Illuminator placement does not have to be perfect as long as there are no obstructions
causing a shadow to be cast across the eye(s) to be tracked.
The Camera Head and Illuminator can be positioned on either side of the Mounting Bar, but a
peripheral illumination source is likely to be desirable so that the camera can have a view of
the eye that is as perpendicular as possible. Having a view of both eyes will enable binocular
recording, or the easy ability to switch between recording left or right eye, something that may
not be possible when the Camera Head is more peripherally placed.
Having said this, there may be situations (e.g., the Siemens 32 channel head coil, or the 8
channel head coil used with the Siemen's, Philips and General Electric Scanners) where more
peripheral placement of the Camera Head (hence central placement of the Illuminator, and
monocular-only recording) is necessary. For instance if the head coil is blocking the Camera
Head's view when it is centrally positioned, then moving the Camera Head more laterally may
be necessary to acquire an unobstructed view. In such cases the eye-to-be-tracked will most
likely remain the same across all subjects to prevent having to reconfigure the mount on a
subject-by-subject basis, as this can be a more time consuming (5-10 minute) procedure.
After determining which side to place the Camera Head and Illuminator, slide these
components onto the Mounting Bar, but do not yet tighten them into place.
A second consideration regarding the Camera Head is whether it needs to be level (for
monocular tracking) or angled (for binocular tracking). See Section 7.3 for detailed steps
regarding angling the Camera Head for binocular recording.
58 Long Range Mount Installation
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the illumination off to the side.