Head-mounted display eyeball tracker integrated system
Head-mounted display with an eye-tracking system and including a light-transmitting substrate ( 20 ) having two major surfaces and edges, optical means for coupling light into said substrate ( 20 ) by total internal reflection, partially-reflecting surfaces ( 22 a - 22 c ) carried by the substrate ( 20 ) that are not parallel with the major surfaces of the substrate ( 20 ), a near-infrared light source ( 78 ) and a display source ( 92 ) projecting within the photopic spectrum, wherein light from the light source ( 78 ) and light from the display source ( 92 ) are coupled into the substrate ( 20 ) by total internal reflection.
1. An optical system for directing a projected image to an eye of a user and for directing infrared light employed for tracking the eye, the optical system comprising:
(a) a lightguide optical element formed as a block of transparent material having a pair of mutually-parallel major external surfaces for guiding image light by internal reflection,
(b) a plurality of image-deflecting surfaces located within said block of transparent material, said plurality of image-deflecting surfaces being mutually parallel, and being angled obliquely to said major external surfaces for coupling-out the image light towards the eye of the user,
(c) an infrared-deflecting surface located within said block of transparent material for deflecting infrared light towards the eye of the user, and
(d) a combination image projector and light source for introducing the projected image and infrared illumination via a common input aperture into said lightguide optical element,
wherein said combination image projector and light source includes a polarizing beam splitter included in a prism, said prism having a first face for input of visible light illumination and infrared illumination, a second face provided with a polarization-modifying reflective spatial light modulator, a third face provided with a quarter-wave phase plate and reflective collimating optics, and an output face optically coupled to said common input aperture, and wherein said polarizing beam splitter is configured to direct visible light entering said first face to as to impinge sequentially on said polarization-modifying reflective spatial light modulator and said reflective collimating optics, and then to enter said common input aperture into said lightguide, and to direct said infrared illumination to said common input aperture without impinging on said polarization-modifying reflective spatial light modulator and said reflective collimating optics.
2. The optical system of claim 1 , wherein said polarizing beam splitter is a chromatically-selective polarizing beam splitter implemented as a multi-layer dielectric coating configured to be:
(a) transparent to visible light having p polarization;
(b) reflective to visible light having s polarization; and
(c) transmissive of a majority of the infrared illumination for both p-polarization and s-polarization.