Customized polymer/glass diffractive waveguide stacks for augmented reality/mixed reality applications
View Patent ↗A diffractive waveguide stack includes first, second, and third diffractive waveguides for guiding light in first, second, and third visible wavelength ranges, respectively. The first diffractive waveguide includes a first material having first refractive index at a selected wavelength and a first target refractive index at a midpoint of the first visible wavelength range. The second diffractive waveguide includes a second material having a second refractive index at the selected wavelength and a second target refractive index at a midpoint of the second visible wavelength range. The third diffractive waveguide includes a third material having a third refractive index at the selected wavelength and a third target refractive index at a midpoint of the third visible wavelength range. A difference between any two of the first target refractive index, the second target refractive index, and the third target refractive index is less than 0.005 at the selected wavelength.
1. A diffractive waveguide stack comprising:
a first diffractive waveguide for guiding light in a first visible wavelength range, the first diffractive waveguide comprising a first material and having a first refractive index and a first yellowness index at a selected wavelength, and a first target refractive index at a midpoint of the first visible wavelength range; and
a second diffractive waveguide for guiding light in a second visible wavelength range, the second diffractive waveguide comprising a second material and having a second refractive index and a second yellowness index at the selected wavelength, and a second target refractive index at a midpoint of the second visible wavelength range; and
a third diffractive waveguide for guiding light in a third visible wavelength range, the third diffractive waveguide comprising a third material and having a third refractive index and a third yellowness index at the selected wavelength, and a third target refractive index at a midpoint of the third visible wavelength range,
wherein:
the first material differs from the second material and the third material, and the second material differs from the third material,
the first visible wavelength range comprises red light, the second visible wavelength range comprises green light, and the third visible wavelength range comprises blue light,
the first yellowness index exceeds the second yellowness index at the selected wavelength, and the second yellowness index exceeds the third yellowness index at the selected wavelength, and
a difference between any two of the first target refractive index, the second target refractive index, and the third target refractive index is less than 0.005.
2. The diffractive waveguide stack of claim 1 , wherein the selected wavelength is 589 nm.
3. The waveguide stack of claim 1 , wherein the first material comprises a first copolymer comprising a first monomer and a second monomer, the second material comprises a second copolymer comprising the first monomer and the second monomer, and a ratio of the first monomer and the second monomer in the first copolymer differs from a ratio of the first monomer and the second monomer in the second copolymer.
4. The waveguide stack of claim 1 , wherein the first material, the second material, and the third material each independently comprises a polymer or a glass.
5. The waveguide stack of claim 1 , wherein:
the first material comprises a first glass, the second material comprises a second glass, and the third material comprises a third glass, wherein the first glass, the second glass, and the third glass are different, or
the first material comprises a first polymer, the second material comprises a second polymer, and the third material comprises a third polymer, wherein the first polymer, the second polymer, and the third polymer are different.
6. The waveguide stack of claim 1 , wherein a field of view the first diffractive waveguide differs from the field of view of the second diffractive waveguide.
7. The waveguide stack of claim 1 , wherein the first material comprises a first polymer and the second material comprises a second polymer.
8. The waveguide stack of claim 7 , wherein the first polymer and the second polymer are different.
9. The waveguide stack of claim 7 , wherein the first material comprises a first copolymer comprising a first monomer and a second monomer and the second material comprises a second copolymer comprising the first monomer and the second monomer.
10. The waveguide stack of claim 9 , where a ratio of the first monomer to the second monomer in the first copolymer differs from a ratio of the first monomer to the second monomer in the second copolymer.
11. The waveguide stack of claim 7 , wherein the first material comprises a first additive and the second material comprises a second additive.
12. The waveguide stack of claim 11 , wherein the first additive and the second additive are the same, and a ratio of the first additive to the first polymer differs from a ratio of the second additive to the second polymer.
13. The waveguide stack of claim 1 , wherein a wavelength in the third visible wavelength range is less than a wavelength in the second visible wavelength range, and a wavelength in the second visible wavelength range is less than a wavelength in the first wavelength range.
14. The waveguide stack of claim 1 , wherein the first yellowness index is less than about 1.2, the second yellowness index is less that about 0.8, and the third yellowness index is less than about 0.4 at the selected wavelength.