Instructions for Use of Eye Tracker
There is one eye tracker system for use in either the 1.5T or 3T
scanner. Move eye tracker system cart into the control room you are
using. The carrying case containing the
camera with mount, interface, power pack and some cables should be on
the cart along with the computer, keyboard and mouse. A monitor already
in place in each control room is used with this system so no monitor is
needed on the cart.
Refer to the connection diagram along with these instructions.
- Unwind several feet of power cord from the outlet strip on the
front of the computer cart. Position the cart under the counter,
just to the right of the equipment cabinet with the back of the
computer facing out. Plug the power cord into any convenient outlet.
cables are bundled together at the back of the computer cart. The six
mating connections are in the equipment cabinet, on the center shelf at
the right side. Join all six cables together. They are:
- HD15 VGA for the primary PC monitor is labeled "1" on both connectors.
- HD15 VGA for the secondary monitor (the
projector) is labeled "2" on both connectors. This display is used to
calibrate the eye tracker.
- DB9 serial connection labeled "3". This joins COM1 of the eye tracker
computer to COM2 of the paradigm PC. This allows the paradigm PC to
control the Viewpoint software on the eye tracker computer.
- ST terminated orange fiber-optic cable joins to the
long fiber that goes into the scan room and connects to the Video
Interface box. Insert the tip of the ST connector and rotate it until the
key lines up. Then insert it fully and rotate the locking ring. Handle
all fiber-optics with care – the ceramic tip is easily broken; the
cable contains glass fiber.
- RJ45 network cable is connected so files can be moved off the eye tracker computer via local network.
cable with BNC connector feeds eye camera video to the RCA Video In of
the DVD Recorder in the equipment cabinet. This allows the eye camera
to be recorded on DVD, if desired and is used when aiming the eye camera.
- Power on the computer by pressing the button on right, front of
computer. This is most easily reached from the left since you are
working from the back. Power on DVD Recorder in the equipment cabinet
and in 3T room set to channel L3, and in 1.5T room to L1.
All camera components are stored in the padded
carrying case. Refer to the connection diagram along with these instructions.
- Preparation before entering the scan room
- Connect the cable from the power
pack to the power connector of the Video Interface box.
- Inspect the
camera carefully - be sure it is pressed all the way onto
the connector at the end of the gooseneck. The camera is removable but
should not be removed except for maintenance.
- Loosen the plastic wing
nuts on the goosneck base slightly so the keyed base projects from the mount.
- Bring in the Interface box and power pack
- Do not walk close to the scanner - keep close to
the wall - carry in the Interface Box and power pack only.
components contain ferrous materials and will be pulled into the magnet
if close enough.
- In 3T the Interface is placed on the same wall as the door,
halfway down. In the 1.5T it is placed on the right side wall just past
the coil storage cabinet.
- Connect the power pack tether snap to the eye bolt in
the wall just below the electrical receptacle.
- Press the Interface box
firmly onto the mating Velcro pad on the gray plastic wiremold.
- Plug the power pack into the receptacle.
- Plug the fiber-optic cable into the mating jack on the Interface box.
- These components are now
secure. Do not remove them while a subject is present in the scan room.
- Take the camera into the scan room - there are no ferrous parts - it does not pull toward the magnet.
- Insert its keyed base into
the widened slot at the foot end of the scanner table so the cable exits in
toward the foot of the table. The preferred
side is the patient's left since this keeps the camera cable clear of
the head coil cable.
- Slide the camera mount to a position just below the head coil.
Adjust the gooseneck to place the camera approximately in position for
eye tracking. Lay the camera power/video cable along the table slot to
the foot end of the table. There are small wedges that can be slid into the table slot to hold the cable in position.
- Connect the camera power/video cable to the interface box.
On the eye tracker computer, start up the ViewPoint software. If all
is well, the Eye Camera window should display live video from the
camera. If not recheck all connections.
Make sure the projector is on and select the NTSC Video source. In
use the Mac Projector Control program, select NTSC button. In 3T
use the Epson IR
remote control, select Video button in the lower covered section. The
eye camera will be projected onto the screen in the magnet bore for use
in aiming the camera. Position the subject and stabilize the head as
securely as possible - this is very important. Head motion is a major
problem during eye
tracking. With the head coil in place, position the camera so the eye
is centered on the screen and almost fills the screen left to right.
Refer to the Viewpoint manual section 4.2 for more on camera setup and
4.4 for instructions on thresholding. Camera position influences
ligthing of the eye. Check that the software can properly detect the
pupil - adjust camera if necessary.
When the subject is advanced to the scan position, calibrate the eye
tracker. Instruct the subject to watch the targets as they appear on
the screen. Tell them to fixate on each target until the next target
begins to appear. In 1.5T use Mac Projector Control program, select the
Computer button and then set the Projecter Video Switch in the
equipment cabinet to "User2", In 3T use the Epson remote control,
select "Computer2" button in the lower
covered section. In the Viewpoint software, Stimuli menu, select
Stimulus Window Properties, Full Screen Monitor 2 so the calibration
window is displayed on the secondary monitor (the projector). Follow
the Calibration instructions (section 4.5 and chapter 6) in the
After successful calibration, switch the projector to display your
stimulus computer. In 1.5T set Projector Video switch to "PC" or "Mac"
position, in 3T use the Epson remote control to select "Computer 1".
© 2007 Kennedy Krieger Institute. Baltimore, Maryland. All rights reserved.