Dispersion compensation

An optical device comprising:

• a waveguide that includes a grating medium, wherein the grating medium has an index of refraction that changes with wavelength at a first rate;
• an input coupling prism mounted to the waveguide, wherein the input coupling prism has an index of refraction that changes with wavelength at a second rate different than the first rate, wherein the input coupling prism is configured to receive light at an external angle of incidence, wherein the light received by the input coupling prism at the external angle of incidence is subject to dispersion at the input coupling prism that separates the light into first light of a first wavelength and second light of a second wavelength different from the first wavelength, and wherein the input coupling prism is configured to couple the first and second light into the waveguide;
• and
• dispersion compensating hologram structures in the grating medium, wherein the first light is incident upon the dispersion compensating hologram structures at a first internal incidence angle, wherein the second light is incident upon the dispersion compensating hologram structures at a second internal incidence angle different from the first internal incidence angle, wherein the dispersion compensating hologram structures are configured to reflect, about a reflective axis offset from a surface normal of the grating medium, the first light as first reflected light, wherein the dispersion compensating hologram structures are configured to reflect, about the reflective axis, the second light as second reflected light, and wherein the dispersion compensating hologram structures are configured to couple the first and second reflected light out of the waveguide.

An optical system comprising:

• a grating medium, wherein the grating medium has an index of refraction that changes with wavelength at a first rate;
• an input coupling prism, wherein the input coupling prism has an index of refraction that changes with wavelength at a second rate different than the first rate, wherein the input coupling prism is configured to receive light at an external angle of incidence, wherein the light received by the input coupling prism at the external angle of incidence is subject to dispersion at the input coupling prism that separates the light into first light of a first wavelength and second light of a second wavelength different from the first wavelength, the first wavelength being between 400-700 nm and the second wavelength being within 20 nm of the first wavelength, wherein the input coupling prism is configured to couple the first and second light into the grating medium, and wherein the grating medium is configured to propagate the first and second light via total internal reflection;
• and
• dispersion compensating hologram structures in the grating medium, wherein the first light is incident upon the dispersion compensating hologram structures at a first internal incidence angle, wherein the second light is incident upon the dispersion compensating hologram structures at a second internal incidence angle different from the first internal incidence angle, wherein the dispersion compensating hologram structures are configured to reflect, about a reflective axis offset from a surface normal of the grating medium, the first light as first reflected light, wherein the dispersion compensating hologram structures are configured to reflect, about the reflective axis, the second light as second reflected light, wherein the dispersion compensating hologram structures are configured to couple the first and second reflected light out of the grating medium, and wherein, after being coupled out of the grating medium by the grating structure, a color separation angle between the first and second reflected light is less than or equal to 0.050°.