Light guide optical assembly

• US 10,473,841 B2
• Filed: 05/28/2019
• Issued: 11/12/2019
• Est. Priority Date: 02/22/2017
• Status: Active Grant

• Current Assignee: Lumus Ltd.
• Original Assignee: Lumus Ltd.
• Inventors: Danziger, Yochay
• Primary Examiner(s): Wong, Tina M
• Application Number:
  US16/423,176
• Publication Number:
  US 20190293856A1
• Time in Patent Office: 168 Days
• Field of Search: None
• CPC Class Codes: G02B 2027/0116 comprising devices for correcting chromatic aberration
• CPC Class Codes: G02B 2027/0125 Field-of-view increase by wavefront division
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G02B 27/0172 characterised by optical features
• CPC Class Codes: G02B 27/10 Beam splitting or combining systems polarising systems G02B27/28; mixing and splitting light signals using optical waveguides G02B6/28; beam shaping, e.g. changing the cross-sectional area, by dividing or superposing multiple light beams G02B27/0905
• CPC Class Codes: G02B 27/28 for polarising used in stereoscopes G02B30/25
• CPC Class Codes: G02B 5/18 Diffraction gratings holographic optical elements G02B5/32, G03H; integrally combined with optical fibres G02B6/02057; for coupling light guides G02B6/34; integrally combined with optical integrated light guides G02B6/12; grating systems G02B27/44
• CPC Class Codes: G02B 6/00 Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
• CPC Class Codes: G02B 6/0016 Grooves, prisms, gratings, scattering particles or rough surfaces
• CPC Class Codes: G02B 6/0028 Light guide, e.g. taper
• CPC Class Codes: G02B 6/0038 Linear indentations or grooves, e.g. arc-shaped grooves or meandering grooves, extending over the full length or width of the light guide
• CPC Class Codes: G02B 6/0075 Arrangements of multiple light guides G02B6/0028 takes precedence
• CPC Class Codes: G02B 6/34 utilising prism or grating G02B6/293 takes precedence

Abstract

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.

Claims

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;

a first diffractive optical component of said pair of matching diffractive optical components configured for coupling light into said at least one lightguide as coupled-in light, said coupled-in light being guided in said at least one lightguide,

said reflective optical component configured to couple said guided coupled-in light from said lightguide as expanded light, and

a second diffractive optical component of said pair of matching diffractive optical components configured for coupling out said coupled-out light,

said components associated with said at least one lightguide and cooperating for two-dimensional expansion of said coupled-in light to said coupled-out light.

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, thereby generating first expanded light;

(b) said reflective optical component is configured for coupling said first expanded light into a second lightguide in a second direction of expansion, thereby generating second expanded light; and

(c) said second diffractive optical component is configured for coupling out 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 wherein:

(a) said lightguide includes a second pair of external surfaces parallel to each other and non-parallel to said first pair of external surfaces; and

(b) said first diffractive optical component is further configured to couple in said coupled-in light with an initial direction of propagation at a coupling angle oblique to both said first and second pairs of surfaces such that said coupled-in light advances by four-fold internal reflection along said lightguide.

4. The apparatus of claim 1 wherein said reflective optical component is configured for two-dimensional (2D) expansion of said first expanded light.

5. 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.

6. The apparatus of claim 1 wherein said reflective optical component is configured in an overlapping relation to said second diffractive optical component.

7. 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.

8. The apparatus of claim 7 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.

9. The apparatus of claim 8 wherein said wavelengths are of red, green, and blue light.

10. The apparatus of claim 8 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.

11. The apparatus of claim 10 wherein:

(a) said reflective optical component is configured to expand said coupled-in light in a first direction of expansion within a first lightguide, thereby generating first expanded light;

(b) said first, third, and fifth diffractive optical components are configured for expanding respective wavelengths of said first expanded light in respective first, second, and third lightguides in a second direction of expansion, thereby generating respective second expanded light; and

(c) said second, fourth, and sixth diffractive optical components are configured for out-coupling said respective 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.