PhotoTransistor Based Eye-Tracking


The applications of eye-tracking devices are endless, which is why we always get excited to see new techniques in measuring the absolute position of the human eye. Cornell students [Michael and John] took on an interesting approach for their final project and designed a phototransistor based eye-tracking system.

We can definitely see the potential of this project, but for their first prototype, the system relies on both eye-tracking and head movement to fully control a mouse pointer. An end-product design was in mind, so the system consists of both a pair of custom 3D printed glasses and a wireless receiver; thus avoiding the need to be tethered to the computer under control . The horizontal position of the mouse pointer is controlled via the infrared eye tracking mechanism, consisting of an Infrared LED positioned above the eye and two phototransistors located on each side of the eye. The measured analog data from the phototransistors determine the eye’s horizontal position. The vertical movement of the mouse pointer is controlled with the help of a 3-axis gyroscope mounted to the glasses. The effectiveness of a simple infrared LED/phototransistor to detect eye movement is impressive, because similar projects we’ve seen have been camera based. We understand how final project deadlines can be, so we hope [Michael and John] continue past the deadline with this one. It would be great to see if the absolute position (horizontal and vertical) of the eye can be tracked entirely with the phototransistor technique.

11 thoughts on “PhotoTransistor Based Eye-Tracking

  1. Since they’ve included a “3-axis” gyro there, why not use it for both vertical and horizontal positioning of the mouse cursor? And use the IR eye tracker for other stuff like enabling the movement of the mouse (if one eye closed), a click (if one eye blinked), and other stuff. Also, with this set-up they could control the speed/acceleration of the mouse cursor.

  2. Uhm, putting infrared led in front of the eye, is sending heat energy right into the eye, and the eye doesn’t have pain receptors to let you know your causing damage.

    So, does this damage the eye or not? I won’t get into a debate, I have my area of expertise in this matter and others have theirs, so I just ask, think about it and research it.

  3. Eye tracking is a terrible method of cursor control for non-disabled people. The position of the eye only roughly correlates to what one’s attention is actually on. Eye movement is a scanning sampled data system. Even a brief reading of a summary of how the human visual system captures and analyzes a scene will tell you how unsuited this is for cursor control. Smoothing this movement out enough to position a cursor, say, between two letters on a page slows it far past the speed of a mouse.

  4. Json,

    I second your opinion on infrared in front of the eyes. Some people think eyes are a copy & paste replacement option.

    You only get one pair eyes…

    Always wear sunglasses in the daytime and in all night clubs that have any ultra-violet effects. Ask any employe that works those venues they always state they have lost sensitivity to low light details of dark areas. I personally know of people who have cases of blindness because of their retina’s where fired. Your Iris doe not clamp down to prevent harm to the eyes.

  5. hm. my contacts block 96% uva, 99% uvb. wonder if a low powered uv led would have a lower overall exposure than ir. not that im particularly worried about it, my laptop display probably has more effect on my eyes than the led theyre using in this project.

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