Boris Greenberg¹, Ward van der Tempel; ¹VoxelSensors

Classical Dual Purkinje Imaging (DPI) faces two major challenges: lateral alignment of the measurement system and accurate detection of P1 and P4 for scale and game factor. Traditionally, these systems rely on a lateral translation mechanism that requires careful alignment and depends on the initial gaze direction. Additionally, P1 and P4 detection relies on maintaining a small angle for proper optical alignment, typically achieved with two separate channels for illumination and signal collection. We propose a novel approach to a DPI system that addresses both challenges. Firstly, our system uses a novel Single Photon Active Event Sensor (SPAES) to simultaneously detect P1 and P4 relative positions on the same matrix with less than a 5-degree angle on the axis, improving accuracy and alignment. Then, to compensate for lateral device misalignment, we use an array of light sources that cover various users' interpupillary distances (IPD). Additionally, we leverage residual retinal scattering to back-illuminate the pupil and measure its dimensions whenever required. This can be done as a separate process with significantly lower sampling rates since pupil dynamics are slower than eye movements (saccades and fixation). We use a MEMS-based scanning element that tracks gaze direction, and our initial gain and offset calibration process allows us to define the system's operating parameters. Therefore, we can use the control response function to determine the eye position in 5D coordinate space. For this purpose, we can periodically resonate the MEMS and determine the deviation from the initial parameters. The same array used for lateral compensation can be used for slippage compensation of the device as any deviation in Z-distance manifests itself in a combination of lateral and angular motion.