With speeds measured in hundreds of degrees per second, measurement of saccadic velocities can be a challenging problem, usually solved by the application of high-frame-rate cameras or high-bandwidth analog systems. This paper describes a novel approach utilizing a standard NTSC video camera coupled with an array of near-infrared light-emitting diodes that are flashed at various times within a single frame. The principle has been demonstrated with a prototype apparatus consisting of 4 16-cell linear arrays ("light sticks"). The cells of each light stick are energized sequentially during each video field, while a camera captures their images reflected in the cornea. When the eye is still, the four line segments are aligned with the vertical and horizontal directions, but when the eye is in motion they appear tilted. Opposite light sticks are cycled in opposite directions, producing opposite tilts. Thus, the measurement of velocity is transformed to a measurement of the angle between two line segments. Preliminary results from a prototype system show a noise level of approximately 20 deg/sec.>>> af++
DE20321242U1
. 2006-09-14
