Pupil tracker
Pupil tracking is useful during AO vision experiments for a few reasons.
- If the camera is properly aligned, it can be used to the subject's pupil into exact alignment with the pivot point of the scanning system.
- Subjects can sit in and out of the system and be rapidly brought back to the same pupil position.
- Small changes in pupil position induce large TCA offsets. TCA can be avoided by monitoring the pupil during experiments. The experimenter can either move the subject to realign the pupil with a reference position (mode 1) or compensate for TCA relative to the reference position with fixed stimulus offsets (mode 2).
In the bottom left corner of AOMcontrol is a button called "Pupil Tracking". Selecting this button will open a new window. An external pupil camera must be properly connected to the computer running AOMcontrol for this feature to work.
All sessions should begin by hitting "Start Video". Make sure that the camera is working properly and the subject's pupil is visible and in focus. Adjust as needed.
After starting the video stream, the experimenter should find a good position of the pupil on the wavefront sensor (AOSACA). When satisfied, select "Set Reference". This will save the current pupil position and use it as a reference going forward.
Mode 1 is currently recommended when image-based TCA is available.
In this mode, the experimenter will now measure TCA using the image based mode and correct for it with offsets in the experimental code.
At this point ICANDI and AOMcontrol will need to be restarted. When both programs have been restarted, open the Pupil Tracking window again. Start the video, but this time select "Load Reference". Find the reference frame saved in the earlier step. This window should now remain open for the duration of your experiment. If AOMcontrol needs to be closed again for any reason, be sure to reload the proper reference frame.
During the experiment, set a tolerance for pupil movement. This is done via the box located in the lower right hand corner of the Pupil Tracking window. When the pupil moves greater than the set distance (relative to the reference position), the program will make a beeping noise. If the noise persists, either ask the subject to adjust themselves via sitting out and back in or move the subject's position with the stage. Continue monitoring the pupil position for the duration of the experiment.