Light guide optical assembly
An optical assembly for optical aperture expansion combines facet reflective technology with diffractive technology. At least two diffractive components having opposite optical power (matching) are used, so that chromatic dispersion introduced by the first diffractive component will then be cancelled by the second diffractive component. The two diffractive components are used in combination with a reflective optical component to achieve more efficient aperture expansion (for near eye display), reducing distortions and noise, while also reducing design constraints on the system and individual components, as compared to conventional techniques. The assembly eliminates and/or reduces the need for polarization management, while enabling wider field of view. In addition, embodiments can have reduced nonuniformity, as compared to conventional single technology implementations, since the distortion patterns of the two technologies do not correlate.
1. An apparatus for optical aperture expansion comprising:
(a) at least one lightguide, said lightguide including a first pair of external surfaces parallel to each other for guiding light by internal reflection;
(b) a pair of first and second matching diffractive optical components; and
(c) a reflective optical component including a set of facets, said set of facets:
(i) including a plurality of partially reflecting facets parallel to each other,
(ii) between said first pair of external surfaces, and
(iii) non-parallel relative to said first pair of external surfaces; and
(d) said components cooperating for expanding coupled-in light to coupled-out light,
(i) said coupled-in light being light coupled into said at least one lightguide,
(ii) said expanding being two-dimensional, and
(iii) said coupled-out light being light coupled out by said reflective optical component.
2. The apparatus of claim 1 wherein
(a) said first diffractive optical component is configured for directing said coupled-in light in a first direction of expansion within a first lightguide of said at least one lightguide, thereby generating first expanded light;
(b) said second diffractive optical component is configured for coupling said first expanded light into a second lightguide of said at least one lightguide, in a second direction of expansion, thereby generating second expanded light; and
(c) said reflective optical component is configured for out-coupling said second expanded light in a third direction as said coupled-out light;
(d) wherein said first, second and third directions are non-parallel to each other.
3. The apparatus of claim 1 further including:
(a) a non-diffractive optical component configured to direct light into said at least one lightguide as said coupled-in light;
(b) wherein said at least one lightguide is one lightguide including:
(i) said first diffractive optical component configured for directing said coupled-in light in a first direction of expansion within said one lightguide, thereby generating first expanded light;
(ii) said second diffractive optical component configured for expanding said first expanded light in said one lightguide in a second direction of expansion, thereby generating second expanded light; and
(iii) said reflective optical component configured for out-coupling said second expanded light in a third direction as said coupled-out light;
(iv) wherein said first, second and third directions are non-parallel to each other.
4. The apparatus of claim 1 further including:
(i) a pair of third and fourth matching diffractive optical components; and
(ii) a pair of fifth and sixth matching diffractive optical components.
5. The apparatus of claim 4 wherein each of said optical components of said matching pairs has a different diffractive spacing from said optical components of other matching pairs, said diffractive spacing such that each of said optical components of said matching pairs deflects a different wavelength through similar angles from said optical components of other matching pairs.
6. The apparatus of claim 5 wherein said wavelengths are of red, green, and blue light.
7. The apparatus of claim 5 wherein:
(a) a first lightguide of said at least one lightguide includes said pair of first and second matching diffractive optical components;
(b) a second lightguide of said at least one lightguide includes said pair of third and fourth matching diffractive optical components; and
(c) a third lightguide of said at least one lightguide includes said pair of fifth and sixth matching diffractive optical components.
8. The apparatus of claim 1 wherein: said first diffractive optical component is configured at a location selected from the group consisting of:
embedded within said reflective optical component, and
on a surface of said reflective optical component.
9. The apparatus of claim 1 wherein: said second diffractive optical component is configured at a location selected from the group consisting of:
embedded within said reflective optical component, and
on a surface of said reflective optical component.
10. The apparatus of claim 1 wherein: said reflective optical component is configured in an overlapping relation to said second diffractive optical component.