High image rate eye movement measurement

Abstract

In contrast to previous devices based on conventional video standards, the present eye tracker is based on programmable CMOS image sensors, interfaced directly to digital processing circuitry to permit real-time image acquisition and processing. This architecture provides a number of important advantages, including image sampling rates of up to 400/s measurement, direct pixel addressing for pre-processing and AOI acquisition, hard-disk storage of relevant image data. The reconfigurable digital processing circuitry (FPGA) also facilitates inline optimisation of the front-end, time-critical processes. The acquisition algorithm for tracking the pupil and other eye features is designed around the generalised Hough transform.The tracker permits comprehensive measurement of eye movement (three degrees of freedom and head movement (six degrees of freedom), and thus provides the basis for many types of vestibulo-oculomotor and visual research. It is foreseen that the device will be used together with appropriate stimulus generators (rotating or translating devices, visual displays).