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 waveguide stack comprising a plurality of optical waveguides, wherein each optical waveguide comprises:
a first edge surface and a second edge surface, wherein the first edge surface faces the second edge surface, and
diffractive incoupling optical elements and diffractive outcoupling optical elements on one or more major surfaces of the waveguide;
a spatial light modulator comprising an output surface for outputting image light having image content for propagation to the diffractive incoupling optical elements; and
a first light absorber directly on the first edge surface and a second light absorber directly on the second edge surface, wherein the first and second light absorbers each comprise a vertically aligned nanotube array, wherein nanotubes of the nanotube arrays extend normal to the one of the first edge or second edge on which the nanotubes are disposed.
2. The display device of claim 1 , wherein the optical device is a head-mounted augmented reality display system, and wherein the outcoupling optical elements are configured to eject the image light propagating within the waveguide.
3. The display device of claim 1 , wherein the film has a thickness of greater than about 100 nm.
4. The display device of claim 1 , wherein each optical waveguide further comprises a top major surface and a bottom major surface.
5. A display device comprising:
a waveguide stack comprising a plurality of optical waveguides, wherein each optical waveguide comprises:
first and second major surfaces and edge surfaces extending therebetween, wherein the edge surfaces comprise a first edge surface facing a second edge surface, and
diffractive incoupling optical elements and diffractive outcoupling optical elements on one or more major surfaces of the waveguide;
a spatial light modulator configured to inject image light into each of the optical waveguides;
a first light absorber film directly contacting the first edge surface, and a second light absorber film directly contacting the second edge surface,
wherein the first and second light absorber films each consist essentially of a vertically aligned nanotube array, wherein nanotubes of the nanotube arrays extend normal to the one of the first edge or second edge on which the nanotubes are disposed.
6. The display device of claim 5 , wherein at least one of the first and second light absorber films absorb at least 90% of incident light having a wavelength ranging from 350 to 850 nm.