Gaze-tracking system and method of tracking user's gaze

A gaze-tracking system for use in a head-mounted display apparatus, the gaze-tracking system comprising:

• at least one illuminator for emitting light pulses;
• at least one first optical element comprising a plurality of micro-to-nano-sized components, the plurality of micro-to-nano-sized components being shaped and arranged relative to each other in a manner that, when incident upon the plurality of micro-to-nano-sized components, a structure of the light pulses is modified to produce structured light, wherein the produced structured light is to be used to illuminate a user's eye when the head-mounted display apparatus is worn by the user;
• at least one camera for capturing an image of reflections of the structured light from the user's eye, wherein the plurality of micro-to-nano-sized components cause the reflections of the structured light to appear as a plurality of glints, each of the plurality of glints being symmetrical about only one axis;
• wherein the plurality of glints are represented in the captured image as positioned within a circular region of a surface of the user's eye, the plurality of glints being arranged into at least two columns, and wherein the plurality of glints are in a form of six characters that are arranged into two columns of three characters each, the characters being V-shaped;
• wherein the image is representative of a form of the reflections and a position of the reflections on an image plane of the at least one camera;
• and
• a processor coupled in communication with the at least one illuminator and the at least one camera, wherein the processor is configured to control the at least one illuminator and the at least one camera, and to process the captured image to detect a gaze direction of the user.