Light-guide optical element employing complementary coated partial reflectors, and light-guide optical element having reduced light scattering
A transparent substrate has two parallel faces and guides collimated image light by internal reflection. A first set of internal surfaces is deployed within the substrate oblique to the parallel faces. A second set of internal surfaces is deployed within the substrate parallel to, interleaved and in overlapping relation with the first set of internal surfaces. Each of the internal surfaces of the first set includes a first coating having a first reflection characteristic to be at least partially reflective to at least a first subset of components of incident light. Each of the internal surfaces of the second set includes a second coating having a second reflection characteristic complementary to the first reflection characteristic to be at least partially reflective to at least a second subset of components of incident light. The sets of internal surfaces cooperate to reflect all components of light from the first and second subsets.
1. An optical device, comprising:
a light-transmitting substrate having at least a first pair of parallel major external surfaces for guiding light indicative of a collimated image by internal reflection at the major external surfaces;
at least one internal surface deployed within the substrate, the internal surface having an end region associated with a first of the major external surfaces of the first pair of major external surfaces defining an interface region between the internal surface and the substrate; and
an amount of a light absorbing material located at the interface region.
2. The optical device of claim 1 , wherein the at least one internal surface includes a plurality of mutually parallel partially reflective surfaces.
3. The optical device of claim 1 , wherein the at least one internal surface is configured to couple light out of the substrate toward an eye of a viewer.
4. The optical device of claim 1 , wherein the at least one internal surface is configured to couple the light guided by internal reflection at the major external surfaces from a first guided direction to a second guided direction.
5. The optical device of claim 1 , wherein the at least one internal surface is configured to couple light into the substrate so as to propagate within the substrate by internal reflection.
6. The optical device of claim 1 , wherein the at least one internal surface is configured to couple light out of the substrate and into a second light-transmitting substrate so as to propagate within the second substrate by internal reflection.
7. The optical device of claim 1 , wherein the amount of the light absorbing material is located at an indentation formed in the first of the major external surfaces at the interface region.
8. The optical device of claim 1 , wherein the internal surface has a second end region associated with a second of the major external surfaces of the first pair of major external surfaces defining a second interface region between the internal surface and the substrate, the optical device further comprising: a second amount of a second light absorbing material located at the second interface region.
9. The optical device of claim 8 , wherein the second amount of the second light absorbing material is located in a second indentation formed in the second of the major external surfaces at the interface region.
10. The optical device of claim 1 , wherein the at least one internal surface is oblique to the first pair of parallel major external surfaces.
11. The optical device of claim 1 , wherein the at least one internal surface is perpendicular to the first pair of parallel major external surfaces.
12. The optical device of claim 1 , wherein the substrate includes a second pair of parallel major external surfaces, the first and second pairs of parallel major external surfaces forming a rectangular cross-section, the substrate configured for guiding light by four-fold internal reflection at the pairs of major external surfaces.
13. The optical device of claim 12 , wherein the at least one internal surface is oblique to a direction of elongation of the substrate.
14. The optical device of claim 12 , wherein the at least one internal surface is oblique to the first pair of parallel major external surfaces and is perpendicular to the second pair of parallel major external surfaces.
15. The optical device of claim 12 , wherein the at least one internal surface is oblique to the first pair of parallel major external surfaces and is oblique to the second pair of parallel major external surfaces.
16. An optical device, comprising:
a light-transmitting substrate having first and second pairs of parallel major external surfaces forming a rectangular cross-section, the substrate configured for guiding light by four-fold internal reflection at the pairs of major external surfaces;
at least one internal surface deployed within the substrate oblique to a direction of elongation of the substrate, the internal surface having an end region associated with one of the major external surfaces of one of the pairs of major external surfaces to define an interface region between the internal surface and the substrate; and
an amount of a light absorbing material located at the interface region.
17. The optical device of claim 16 , wherein the at least one internal surface includes a plurality of mutually parallel partially reflective surfaces.
18. The optical device of claim 16 , wherein the at least one internal surface is oblique to the first pair of parallel major external surfaces and perpendicular to the second pair of parallel major external surfaces.
19. The optical device of claim 16 , wherein the at least one internal surface is oblique to the first pair of parallel major external surfaces and oblique to the second pair of parallel major external surfaces.
20. The optical device of claim 16 , further comprising: a second amount of a second light absorbing material located at a blemish formed at an external region of the substrate that excludes the interface region.