Patterning of high refractive index glasses by plasma etching
Plasma etching processes for forming patterns in high refractive index glass substrates, such as for use as waveguides, are provided herein. The substrates may be formed of glass having a refractive index of greater than or equal to about 1.65 and having less than about 50 wt % SiO 2 . The plasma etching processes may include both chemical and physical etching components. In some embodiments, the plasma etching processes can include forming a patterned mask layer on at least a portion of the high refractive index glass substrate and exposing the mask layer and high refractive index glass substrate to a plasma to remove high refractive index glass from the exposed portions of the substrate. Any remaining mask layer is subsequently removed from the high refractive index glass substrate. The removal of the glass forms a desired patterned structure, such as a diffractive grating, in the high refractive index glass substrate.
1. A head-mountable augmented reality display system comprising:
a spatial light modulator configured to output light with image information; and
a waveguide configured to transmit ambient light to provide a user with a view of the world, receive and incouple the outputted light from the spatial light modulator, and output the incoupled light towards an eye of the user,
wherein the waveguide is formed of an optically transmissive material having a refractive index of greater than or equal to about 1.65, wherein more than about 50 wt % of the waveguide is formed of one or more of B 2 O 3 , Al 2 O 3 , ZrO 2 , Li 2 O, Na 2 O, K 2 O, MgO, CaO, SrO, BaO, ZnO, La 2 O 3 , Nb 2 O 5 , TiO 2 , HO, and Sb 2 O 3 , and wherein the waveguide comprises:
incoupling optical elements in a first region of the waveguide, the incoupling optical elements comprising a first diffractive grating formed by first recesses in the waveguide, and
outcoupling optical elements in a second region of the waveguide, the outcoupling optical elements comprising a second diffractive grating formed by second recesses in the waveguide,
wherein the first recesses and the second recesses each have straight sidewalls, a width between the sidewalls of less than about 1 micron, and an aspect ratio of in a range of about 1:10 to about 10:1.
2. The head-mountable augmented reality display system of claim 1 , wherein the waveguide is formed by a plurality of metal oxides selected from the group consisting of B 2 O 3 , Al 2 O 3 , ZrO 2 , Li 2 O, Na 2 O, K 2 O, MgO, CaO, SrO, BaO, ZnO, La 2 O 3 , Nb 2 O 5 , TiO 2 , HfO, and Sb 2 O 3 .
3. The head-mountable augmented reality display system of claim 1 , wherein the waveguide has less than about 30 wt % SiO 2 .
4. The head-mountable augmented reality display system of claim 3 , wherein the waveguide has less than about 20 wt % SiO 2 .
5. The head-mountable augmented reality display system of claim 1 , wherein the waveguide consists of SiO 2 , B 2 O 3 , TiO 2 , La 2 O 3 , ZrO 2 , Nb 2 O 5 , CaO, and Li 2 O.
6. The head-mountable augmented reality display system of claim 1 , wherein the width is less than about 300 nm.
7. The head-mountable augmented reality display system of claim 1 , wherein the width is about 10 nm to about 100 nm.
8. The head-mountable augmented reality display system of claim 1 , wherein the aspect ratio in a range of about 3:1 to about 10:1.
9. The head-mountable augmented reality display system of claim 1 , wherein the width is 10 nm to 500 nm.
10. The head-mountable augmented reality display system of claim 9 , wherein the width is 100 nm to 500 nm.
11. The head-mountable augmented reality display system of claim 1 , wherein the optically transmissive material has a refractive index of greater than or equal to about 1.70.
12. The head-mountable augmented reality display system of claim 1 , further comprising a third diffraction grating formed by third recesses in a third region of the waveguide, wherein the third diffraction grating defines an orthogonal pupil expander configured to redirect light from the incoupling optical elements to the outcoupling optical elements.
13. The head-mountable augmented reality display system of claim 12 , wherein the third recesses each have straight sidewalls, a width between the sidewalls of less than about 1 micron, and an aspect ratio of in a range of about 1:10 to about 10:1.
14. The head-mountable augmented reality display system of claim 1 , further comprising a light source configured to direct light to the spatial light modulator, wherein the spatial light modulator is configured to modulate the light from the light source, wherein the modulated light is the outputted light with image information.
15. The head-mountable augmented reality display system of claim 1 , wherein the incoupling optical elements are configured to redirect the outputted light from the spatial light modulator into the waveguide at angles for total internal reflection through the waveguide.
16. The head-mountable augmented reality display system of claim 1 , wherein the waveguide is one of a plurality of waveguides forming a waveguide stack.
17. The head-mountable augmented reality display system of claim 16 , wherein outcoupling optical elements of some waveguides of the plurality of waveguides output light with different amounts of wavefront divergence than outcoupling optical elements of other waveguides of the plurality of waveguides.
18. The head-mountable augmented reality display system of claim 16 , wherein incoupling optical elements of some waveguides of the plurality of waveguides are configured to incouple light of different wavelengths than incoupling optical elements of other waveguides of the plurality of waveguides.
19. The head-mountable augmented reality display system of claim 1 , wherein the light modulator is a LCOS display.