System for collecting light
A thin transparent layer can be integrated in a head mounted display device and disposed in front of the eye of a wearer. The thin transparent layer may be configured to output light such that light is directed onto the eye to create reflections therefrom that can be used, for example, for glint based tracking. The thin transparent layer can be configured to reduced obstructions in the field of the view of the user.
1. A head-mounted display system configured to project light to an eye of a user to display augmented reality image content in a vision field of said user, said head-mounted display system comprising:
a frame configured to be supported on a head of the user;
an image projector configured to project images into the user's eye to display image content in the vision field of the user;
a waveguide;
at least one coupling optical element configured such that light is coupled into said waveguide and guided therein;
first and second light redirecting elements disposed to receive light from said at least one coupling optical element that is guided within the waveguide,
wherein the first light redirecting element comprises a first set of diffractive optical elements configured to direct at least a portion of the light received from said at least one coupling optical element to the second light redirecting element and to outcouple, from the waveguide, light received from the second light redirecting element, and
wherein the second light redirecting element comprises a second set of diffractive optical elements configured to direct at least a portion of the light received from said at least one coupling element to the first light redirecting element and to outcouple, from the waveguide, light received from the first light redirecting element,
wherein each of the at least one coupling optical element, the first light redirecting element, and the second light redirecting element has a respective grating vector, and
wherein the grating vector of the first light redirecting element is oriented at a first angle relative to an edge of the waveguide, the grating vector of the second light redirecting element is oriented at a second angle relative to the edge of the waveguide, and the grating vector of the at least one coupling element is oriented at a third angle relative to the edge of the waveguide, each of the first angle, the second angle, and the third angle being different; and
a camera arranged to receive outcoupled light from both the first set of diffractive optical elements and the second set of diffractive optical elements.
2. The system of claim 1 , wherein said first and second light redirecting elements form an angle with respect to each other.
3. The system of claim 1 , wherein said first and second light redirecting elements form an angle with respect to each other of greater than 0° and less than 180°.
4. The system of claim 1 , wherein said first and second light redirecting elements form an angle with respect to each other of greater than 75° and less than 160°.
5. The system of claim 1 , wherein said first and second light redirecting elements are angled with respect to each other so as to form a chevron shape.
6. The system of claim 1 , wherein the first and second light redirecting elements comprise diffractive optical elements.
7. The system of claim 1 , wherein the first and second light redirecting elements each comprise diffractive features and the diffractive features of the first light redirecting element and the diffractive features of the second light redirecting element are oriented at an angle with respect to each other.
8. The system of claim 7 , wherein the diffractive features of the first light redirecting element and the diffractive features of the second light redirecting element are oriented at an angle with respect to each other of more than 90° and less than 170°.
9. The system of claim 7 , wherein the diffractive features of the first light redirecting element and the diffractive features of the second light redirecting element are oriented at an angle with respect to each other of more than 100° and less than 140°.
10. The system of claim 1 , wherein the first and second light redirecting elements have a straight border therebetween, said first and second redirecting light elements are configured to direct light to said border.
11. The system of claim 1 , wherein the first and second light redirecting elements have a non-straight border therebetween.
12. The system of claim 1 , wherein the first and second light redirecting elements have an undulating border therebetween.
13. The system of claim 1 , wherein the first and second light redirecting elements have a sawtooth shaped border therebetween.
14. The system of claim 1 , wherein the first and second redirecting elements are interlocking.
15. The system of claim 1 , wherein a first portion of the first light redirecting element extends further away from the center of the first light redirecting element and closer to the center of the second light redirecting element than a first portion of the second light redirecting element.
16. The system of claim 1 , wherein a first portion of the second light redirecting element extends further away from the center of the second light redirecting element and closer to the center of the first light redirecting element than a first portion of the first light redirecting element.
17. The system of claim 1 , wherein the first and second light redirecting elements each have a grating vector, said grating vectors angled with respect to each other.
18. The system of claim 1 , wherein the first and second light redirecting elements each have a grating vector, said grating vectors angled about 120° with respect to each other.
19. The system of claim 1 , wherein the first and second light redirecting elements each have a grating vector, said grating vectors angled between 130° to 150° with respect to each other.
20. The system of claim 1 , wherein the first and second light redirecting elements each have a grating vector, said grating vectors angled between 140° to 160° with respect to each other.