Stacked waveguides having different diffraction gratings for combined field of view

Patent metadata

Field	Value
Publication number	US-11269144-B2
Application number	US-201815926920-A
Country	US
Kind code	B2
Filing date	Mar 20, 2018
Priority date	Mar 21, 2017
Publication date	Mar 8, 2022
Grant date	Mar 8, 2022

Abstract

In one aspect, an optical device comprises a plurality of waveguides formed over one another and having formed thereon respective diffraction gratings, wherein the respective diffraction gratings are configured to diffract visible light incident thereon into respective waveguides, such that visible light diffracted into the respective waveguides propagates therewithin. The respective diffraction gratings are configured to diffract the visible light into the respective waveguides within respective field of views (FOVs) with respect to layer normal directions of the respective waveguides. The respective FOVs are such that the plurality of waveguides are configured to diffract the visible light within a combined FOV that is continuous and greater than each of the respective FOVs.

First claim

What is claimed is:

1. An optical device, comprising:
a plurality of waveguides formed over one another in a vertical direction and having respective top surfaces, the respective top surfaces having formed thereon respective diffraction gratings, wherein the respective diffraction gratings are configured to diffract visible light incident thereon into respective waveguides, such that the visible light diffracted into the respective waveguides propagates therewithin,
wherein the respective diffraction gratings overlap one another when viewed in the vertical direction, and
wherein the respective diffraction gratings are configured to diffract the visible light having the same color of one of blue, green and red colors incident on the respective waveguides within respective field of views (FOVs) into the respective waveguides with respect to layer normal directions of the respective waveguides, wherein the respective FOVs correspond to ranges of incident angles of the visible light incident on the respective waveguides within which the respective diffraction gratings are configured to diffract the visible light, and wherein the respective FOVs are such that the plurality of waveguides are configured to diffract the visible light within a combined FOV that is continuous and greater than each of the respective FOVs,
wherein the plurality of waveguides includes:
a first waveguide having formed thereon a first diffraction grating configured to diffract the visible light incident thereon within a first FOV while transmitting therethrough the visible light within a second FOV outside of the first FOV, and
a second waveguide having formed thereon a second diffraction grating configured to diffract the visible light transmitted through the first diffraction grating and incident thereon within the second FOV.

2. The optical device of claim 1 , wherein the waveguides are formed of a material whose refractive index is smaller than an effective refractive index of the respective diffraction gratings, such that the visible light diffracted into the respective waveguides propagates therewithin under total internal reflection.

3. The optical device of claim 1 , wherein the plurality of waveguides are in a stacked arrangement and are configured to propagate the visible light in substantially parallel directions under total internal reflection.

4. The optical device of claim 1 , wherein different ones of the respective FOVs do not overlap by more than 20% on the basis of a sum of the different ones of the respective FOVs.

5. The optical device of claim 1 , wherein the first and second diffraction gratings have different periods and are configured to diffract visible light having different wavelengths while having the same color.

6. The optical device of claim 1 , wherein the first and second diffraction gratings have substantially the same period and are configured to diffract visible light having substantially the same wavelength.

7. The optical device of claim 1 , wherein the first diffraction grating has a first period and is configured to diffract visible light having a first wavelength, wherein the second diffraction grating has a second period and is configured to diffract visible light having a second wavelength, and wherein the first wavelength is shorter compared to the second wavelength.

8. The optical device of claim 7 , further comprising a third waveguide having formed thereon a third diffraction grating having a third period and configured to diffract visible light having a third wavelength, wherein the second wavelength is shorter compared to the third wavelength.

9. The optical device of claim 8 , wherein the second diffraction grating is configured to transmit the visible light having the second wavelength, and wherein the third diffraction grating is configured to diffract within the second FOV the transmitted visible light having the second wavelength from the second diffraction grating.

10. The optical device of claim 9 , wherein the first and second diffraction gratings are configured to transmit the visible light having the third wavelength, and wherein the third diffraction grating is configured to diffract within the first FOV the visible light having the third wavelength that is transmitted through the first and second diffraction gratings.

11. An optical system, comprising:
a first waveguide having a first top surface, the first top surface having formed thereon a first diffraction grating, the first diffraction grating having a first period and configured to diffract visible light having a first color that is incident on the first waveguide within a first field of view (FOV) while transmitting therethrough the visible light within a second FOV outside of the first FOV; and
a second waveguide having a second top surface, the second top surface having formed thereon a second diffraction grating, the second diffraction grating having a second period and configured to diffract the visible light having the first color that is transmitted through the first diffraction grating and incident on the second waveguide within the second FOV,
wherein the first and second waveguides are formed over one another in a vertical direction,
wherein the first and second diffraction gratings overlap one another when viewed in the vertical direction and are configured to diffract the visible light having the first color within respective FOVs into the respective waveguides with respect to layer normal directions of the respective waveguides, wherein the respective FOVs correspond to ranges of incident angles of the visible light incident on the respective waveguides within which respective ones of the first and second diffraction gratings are configured to diffract the visible light, and wherein the respective FOVs are such that the first and second diffraction gratings are configured to diffract the visible light having the first color of one of blue, green and red colors within a combined FOV that is continuous and greater than each of the first and second FOVs.

12. The optical system of claim 11 , wherein the first waveguide and the second waveguide are in a stacked configuration, wherein the first waveguide is configured to receive the visible light having the first color prior to the second waveguide, wherein the first period is shorter than the second period.

13. The optical system of claim 12 , wherein the second diffraction grating is configured to diffract the visible light having the first color within the second FOV after substantially transmitting through the first diffraction grating without substantially diffracting.

14. The optical system of claim 13 , wherein the first diffraction grating is configured to substantially transmit therethrough without substantially diffracting the visible light having a second color, wherein the visible light having the second color has a longer wavelength compared to the light having the first color.

15. The optical system of claim 14 , wherein the second diffraction grating is configured to diffract the visible light having the second color within the second FOV to be guided in the second waveguide.

16. The optical system of claim 11 , wherein each of the first and second diffraction gratings comprises a cholesteric liquid crystal (CLC) layer.

17. The optical system of claim 16 , wherein the CLC layer comprises:
a plurality of chiral structures, wherein each chiral structure comprises a plurality of liquid crystal molecules that extend in a layer depth direction by at least a helical pitch and are successively rotated in a first rotation direction,

Assignees

• Magic Leap Inc

Inventors

• Oh Chulwoo
• Parthiban Vikraman

Classifications

• G02B6/34 Primary

  utilising prism or grating {(G02B6/293 takes precedence)} · CPC title

• G02B2027/0123

  comprising devices increasing the field of view · CPC title

• G02F1/292

  by controlled diffraction or phased-array beam steering (controlled diffraction for optical switching G02F1/31) · CPC title

• G02B2027/0187

  slaved to motion of at least a part of the body of the user, e.g. head, eye · CPC title

• G02B2027/0134

  of stereoscopic type · CPC title