Holographic pattern generation for head-mounted display (HMD) eye tracking using a diffractive optical element
A system for making a holographic medium for use in generating light patterns for eye tracking includes a light source configured to provide light and a beam splitter configured to separate the light into a first portion of the light and a second portion of the light that is spatially separated from the first portion of the light. The system also includes a first set of optical elements configured to transmit the first portion of the light for providing a first wide-field beam onto an optically recordable medium and one or more diffractive optical elements configured to receive the second portion of the light and project a plurality of separate light patterns onto the optically recordable medium for forming the holographic medium.
1. A system for making a holographic medium for use in generating light patterns for eye tracking, the system including:
a light source configured to provide light;
a beam splitter configured to separate the light into a first portion of the light and a second portion of the light that is spatially separated from the first portion of the light;
a first set of optical elements configured to transmit the first portion of the light for providing a first wide-field beam onto an optically recordable medium;
one or more diffractive optical elements configured to receive the second portion of the light and project a plurality of separate light patterns onto the optically recordable medium for forming the holographic medium; and
one or more diffusers configured to expand the plurality of separate light patterns from the one or more diffractive optical elements by diffusing light from the one or more diffractive optical elements.
2. The system of claim 1 , wherein the light provided by the light source is coherent light.
3. The system of claim 1 , wherein the one or more diffractive optical elements are configured to project a first light pattern of the plurality of separate light patterns onto the optically recordable medium at a first angle, and project a second light pattern of the plurality of separate light patterns onto the optically recordable medium at a second angle that is distinct from the first angle.
4. The system of claim 1 , wherein the one or more diffractive optical elements are optically coupled with one or more lenses configured to focus light from the one or more diffractive optical elements.
5. The system of claim 1 , wherein the one or more diffractive optical elements include one or more diffractive beam splitters configured to project an array of spots.
6. The system of claim 1 , wherein the one or more diffractive optical elements are optically coupled with a plurality of lenses, a first lens of the plurality of lenses configured to focus a first portion of light from the one or more diffractive optical elements and a second lens of the plurality of lenses configured to focus a second portion, distinct from the first portion, of light from the one or more diffractive optical elements.
7. The system of claim 6 , wherein the plurality of lenses is arranged in a microlens array.
8. The system of claim 1 , wherein the plurality of separate light patterns is arranged in a circular configuration.
9. The system of claim 1 , wherein the plurality of separate light patterns is arranged in a rectangular configuration.
10. The system of claim 1 , including a second set of optical elements configured to direct the second portion of the light toward the one or more diffractive optical elements.
11. A method for making a holographic medium for use in generating light patterns for eye tracking, the method including:
providing light from the light source of the system of claim 1 ;
separating, with the beam splitter of the system, the light into a first portion of the light and a second portion of the light that is spatially separated from the first portion of the light;
transmitting the first portion of the light through the first set of optical elements of the system to provide a first wide-field beam;
transmitting the second portion of the light through the one or more diffractive optical elements of the system to provide a plurality of separate light patterns;
concurrently projecting the first wide-field beam and the plurality of separate light patterns onto an optically recordable medium to form the holographic medium; and
diffusing, with the one or more diffusers, light from the one or more diffractive optical elements.
12. The method of claim 11 , including focusing, with one or more lenses, light from the one or more diffractive optical elements.
13. The method of claim 11 , including projecting the one or more diffractive optical elements, a first light pattern of the plurality of separate light patterns onto the optically recordable medium at a first angle, and projecting, with the one or more diffractive optical elements, a second light pattern of the plurality of separate light patterns onto the optically recordable medium at a second angle that is distinct from the first angle.
14. The method of claim 11 , including directing, with a second set of optical elements, the second portion of the light toward the one or more diffractive optical elements.
15. The system of claim 1 , further including one or more lenses located between the one or more diffusers and the one or more diffractive optical elements.
16. The system of claim 1 , wherein a two-dimensional pattern of the plurality of separate light patterns is arranged in a barrel or pin-cushion configuration.
17. The system of claim 1 , wherein a two-dimensional pattern of the plurality of separate light patterns includes a first area that is not illuminated by the plurality of separate light patterns and a second area illuminated by the plurality of separate light patterns, the second area surrounding the first area.