Waveguides with light absorbing films and processes for forming the same
In some embodiments, a display device includes one or more waveguides having a vapor deposited light absorbing film on edges of the waveguide to mitigate ghost images. In some embodiments, the film is formed directly on the edge of the waveguide by a vapor deposition, such as an evaporative deposition process. In some embodiments, the light absorbing films may comprise carbon, for example carbon in the form of one or more allotropes of carbon, such as fullerenes, or black silicon.
1. A display device comprising:
a plurality of waveguides, each waveguide comprising:
top and bottom major surfaces, and first, second, third, and fourth edges extending between the respective top and bottom manor surfaces, wherein the first edge is opposite the second edge and the third edge is opposite the fourth edge on each waveguide,
an incoupling optical element on one of the top and bottom major surfaces,
an outcoupling optical element on one of the top and bottom major surfaces, wherein the outcoupling optical element is laterally spaced apart from the incoupling optical element as seen in a top-down plan view of the plurality of waveguides, and
an orthogonal pupil expander on one of the top and bottom major surfaces, wherein the orthogonal pupil expander is proximal to the first edge,
wherein the incoupling optical element of a first waveguide of the plurality of waveguides is arranged to incouple blue light into the first waveguide,
wherein the incoupling optical element of a second waveguide of the plurality of waveguides is arranged to incouple green light into the second waveguide, and
wherein the incoupling optical element of a third waveguide of the plurality of waveguides is arranged to incouple red light into the third waveguide; and
a light projection system configured to output light having image content for propagation to at least one of the incoupling optical elements;
wherein at least one of the plurality of waveguides further comprises:
a first light absorber directly on the first edge proximal to the at least one orthogonal pupil expander of the respective waveguide; and
a third light absorber directly on the third edge that is adjacent to the first edge of the respective waveguide, wherein the third light absorber is laterally more proximal to the third incoupling optical element than to the first incoupling optical element or the second incoupling optical element as seen in a top-down plan view of the plurality of waveguides,
wherein the first light absorber comprises a first vertically aligned nanotube array, wherein nanotubes of the first nanotube array extend normal to the first edge of the respective waveguide, and
wherein the third light absorber comprises a third vertically aligned nanotube array, wherein nanotubes of the third nanotube array extend normal to the third edge of the respective waveguide.
2. The display device of claim 1 , wherein the display device is a head-mounted augmented reality display system, and wherein the outcoupling optical element of each respective waveguide is configured to eject the image light propagating within the waveguide into an eye of wearer of the head mounted augmented reality display system.
3. The display device of claim 1 , wherein the plurality of waveguides forms a waveguide stack.
4. The display device of claim 3 , wherein each waveguide of the waveguide stack comprises a respective first light absorber directly on a respective first edge of the waveguide and a respective third light absorber directly on a respective third edge of the waveguide.
5. The display device of claim 3 , wherein the waveguide stack comprises adhesive joining together waveguides of the stack, the adhesive forming a gas tight volume between joined waveguides.
6. The display device of claim 5 , further comprising spacers between the joined waveguides.
7. The display device of claim 3 , wherein some waveguides of the waveguide stack comprise outcoupling optical elements configured to eject light of different wavelengths than outcoupling optical elements of other waveguides of the waveguide stack.
8. The display device of claim 3 , wherein some waveguides of the waveguide stack comprise outcoupling optical elements configured to eject light with different amounts of wavefront divergence than outcoupling optical elements of other waveguides of the waveguide stack.
9. The display device of claim 1 wherein the orthogonal pupil expander of each waveguide is laterally spaced apart from each of the incoupling optical elements and is laterally spaced apart from the outcoupling optical element of the respective waveguide, as seen in a top-down plan view of the plurality of waveguides.
10. The display device of claim 1 , wherein the outcoupling optical element of each waveguide is an exit pupil expander.
11. The display device of claim 1 , wherein the outcoupling optical element of each waveguide comprises a polymer.
12. The display device of claim 1 , wherein the at least one of the plurality of waveguides further comprises a second light absorber directly on the second edge.
13. The display device of claim 12 , wherein the second light absorber is absorptive of at least 90% of incident light having a wavelength ranging from 350 to 850 nm.
14. The display device of claim 12 , wherein the second light absorber comprises a second vertically aligned nanotube array, wherein nanotubes of the second vertically aligned nanotube array extend normal to the second edge of the respective waveguide.
15. The display device of claim 1 , wherein each of the first and third vertically aligned nanotube arrays comprises a plurality of substantially parallel carbon nanotubes.
16. The display device of claim 1 , wherein at least one of the first light absorber or the third light absorber is absorptive of at least 90% of incident light having a wavelength ranging from 350 to 850 nm.