This week Jenny and myself took a flight to Nuremberg (via Amsterdam) to visit PlusOptix to view their PowerRef3 ( http://www.plusoptix.com/lang-en/accommodation-meter.html ). It made a pleasant change from being in the lab everyday to get on a plane and look at some equipment (I was very excited).
We arrived and were greeted by Ralph, an employee of the company who took us to look at the equipment.
The idea behind the PowerRef 3 is to use a mirror system to shine infared light into the eyes and record the reflections from the back of the retina to determine both each eyes position (and hence gaze, from which VERGENCE can be measured) and also the refraction of the eyes (which is a way to measure the ACCOMMODATION). We are planning the main study of my PhD to involve looking at the decoupling of the two cues above and so were very impressed by the equipments accuracy and ease of use. The clever way PlusOptix do the calculations is to insist the camera is located one metre away from the eye for the distance the infared light travels. This means that calibration (which I am told by Jenny is a nightmare with conventional eyetracker technology) is not required, as everything is calculated from measurable numbers in relation to this distance of 1 metre.
Jenny and I discussed the mathematics behind the data, and created some matlab code to run our own evaluations on the accuracy and reliabiliity of the data with regards to a theoretical ‘perfect’ case and we were astounded by how similar the results were. I am very much looking forward to getting the lab a PowerRef 3 to run our experiments with.
As a closing note it is worth mentioning that the people at PlusOptix from the boss all the way down to the general workforce were polite, kind and interested in saying hello and talking to us. Ralph, who gave up two days to look after us, and Christian, who I had been in contact with before heading over there, were very generous and helped make the couple of days away be much more enjoyable!
🙂 well on reflection claiming that calibration with a standard eye-tracker is a “nightmare” was exaggeration, but I feel I could justify the term “faff”.