US-12625351-B2 - Image capture at varying optical powers

Abstract

An imaging device includes an image pixel array and a plurality of micro-electro-mechanical systems (MEMS) Alvarez tunable lenses disposed over regions of the imaging pixels. The MEMS Alvarez tunable lenses are configured to be adjusted to varying optical powers to focus image light to the plurality of imaging pixels at varying focus depths. Processing logic is configured to drive the plurality of MEMS Alvarez tunable lenses to provide varying optical powers to focus the image light to the imaging pixels during a plurality of image captures with the imaging pixels.

Inventors

• Youmin Wang
• Yatong An

Assignees

• META PLATFORMS TECHNOLOGIES, LLC

Dates

Publication Date

20260512

Application Date

20230913

Claims (20)

1. 1 . A head mounted device comprising: an illumination module configured to illuminate an eyebox region with non-visible illumination light; an imaging device configured to sense returning light that is the non-visible illumination light reflecting or scattering from the eyebox region, wherein the imaging device includes: an image pixel array including a plurality of imaging pixels; and a plurality of micro-electro-mechanical systems (MEMS) Alvarez tunable lenses disposed over regions of the imaging pixels; and processing logic configured to drive the plurality of MEMS Alvarez tunable lenses to provide varying optical powers to focus the returning light to the imaging pixels during a plurality of image captures with the imaging pixels, wherein the processing logic is configured to combine the image captures at the varying optical powers into a light field image.
2. 2 . The head mounted device of claim 1 , wherein the image pixel array includes single-photon avalanche diodes (SPADs).
3. 3 . The head mounted device of claim 1 , wherein the MEMS Alvarez tunable lenses include a first optical element and a second optical element that provide the varying optical powers when laterally shifted with respect to each other, and wherein the first optical element includes a first metasurface to provide the varying optical powers.
4. 4 . The head mounted device of claim 1 , wherein the MEMS Alvarez tunable lenses include a first optical element and a second optical element that provide the varying optical powers when laterally shifted with respect to each other, and wherein the first optical element has a first surface defined by a first cubic phase surface, and wherein the second optical element has a second surface defined by a second cubic phase surface.
5. 5 . The head mounted device of claim 4 , wherein the first cubic phase surface is the same as the second cubic phase surface.
6. 6 . The head mounted device of claim 1 , wherein an imaging plane of the image pixel array is defined in a two-dimensional x-y plane, and wherein the MEMS Alvarez tunable lenses are adjusted along an x-axis of the two-dimensional x-y plane.
7. 7 . The head mounted device of claim 6 , wherein the MEMS Alvarez tunable lenses include a combdrive to traverse along the x-axis.
8. 8 . The head mounted device of claim 1 , wherein each of the MEMS Alvarez tunable lenses are configured to focus image light to a plurality of the imaging pixels in a corresponding region of the regions of the imaging pixels.
9. 9 . The head mounted device of claim 1 , wherein providing the varying optical powers during the plurality of image captures includes: driving the MEMS Alvarez tunable lenses to traverse to first positions along an axis to provide a first focus depth to the image pixel array; initiating a first image capture with the image pixel array while the MEMS Alvarez tunable lenses are at the first positions; driving the MEMS Alvarez tunable lenses to traverse to second positions along the axis to provide a second focus depth to the image pixel array; and initiating a second image capture with the image pixel array while the MEMS Alvarez tunable lenses are at the second positions.
10. 10 . An imaging device comprising: an image pixel array including a plurality of imaging pixels; a plurality of micro-electro-mechanical systems (MEMS) Alvarez tunable lens disposed over regions of the imaging pixels, wherein the imaging device is configured to sense returning light that is a non-visible illumination light reflecting or scattering from an eyebox region; and processing logic configured to drive the plurality of MEMS Alvarez tunable lenses to provide varying optical powers to focus the returning light to the imaging pixels during a plurality of image captures with the imaging pixels, wherein the processing logic is configured to combine the image captures at the varying optical powers into a light field image.
11. 11 . The imaging device of claim 10 , wherein the image pixel array includes single-photon avalanche diodes (SPADs).
12. 12 . The imaging device of claim 10 , wherein the MEMS Alvarez tunable lens includes a first optical element and a second optical element that provide a first focus depth and a second focus depth when laterally shifted with respect to each other, and wherein the first optical element includes a first metasurface.
13. 13 . The imaging device of claim 10 , wherein the MEMS Alvarez tunable lens includes a first optical element and a second optical element that provide varying optical powers when laterally shifted with respect to each other, and wherein the first optical element has a first surface defined by a first cubic phase surface, and wherein second optical element has a second surface defined by a second cubic phase surface.
14. 14 . The imaging device of claim 10 , wherein a first focus depth is a cornea-plane and a second focus depth is a retina-plane.
15. 15 . The imaging device of claim 10 , wherein an imaging plane of the image pixel array is defined in a two-dimensional x-y plane, and wherein the MEMS Alvarez tunable lens is adjusted along an x-axis of the two-dimensional x-y plane.
16. 16 . The imaging device of claim 15 , wherein the MEMS Alvarez tunable lens includes a combdrive to traverse along the x-axis.
17. 17 . A system comprising: an illumination module configured to illuminate an eyebox region with non-visible illumination light; an imaging device configured to sense returning light that is the non-visible illumination light reflecting or scattering from an eyebox region, wherein the imaging device includes: an image pixel array having a plurality of imaging pixels; and a plurality of micro-electro-mechanical systems (MEMS) Alvarez tunable lenses disposed over regions of the imaging pixels, wherein the MEMS Alvarez tunable lenses are configured to be adjusted to varying optical powers to focus image light to the plurality of imaging pixels at varying focus depths; and processing logic configured to drive the plurality of MEMS Alvarez tunable lenses to provide the varying optical powers to focus the image light to the imaging pixels during a plurality of image captures with the imaging pixels, wherein the processing logic is configured to combine the image captures at the varying optical powers into a light field image.
18. 18 . The system of claim 17 , wherein the image pixel array includes single-photon avalanche diodes (SPADs).
19. 19 . The system of claim 17 , wherein the MEMS Alvarez tunable lenses include a first optical element and a second optical element that provide the varying optical powers when laterally shifted with respect to each other, and wherein the first optical element includes a first metasurface to provide the varying optical powers.
20. 20 . The system of claim 17 , wherein the MEMS Alvarez tunable lenses include a combdrive to traverse along an x-axis of an imaging plane of the image pixel array.

Description

TECHNICAL FIELD This disclosure relates generally to optics, and in particular to capturing images at varying optical powers. BACKGROUND INFORMATION Light field microscopy includes capturing images at various depths of field. Various “light field cameras” have been sold in the past. Existing systems typically suffer from relatively low speed image capture or require a large number of image pixels to generate images with suitable resolutions. BRIEF DESCRIPTION OF THE DRAWINGS Non-limiting and non-exhaustive embodiments of the invention are described with reference to the following figures, wherein like reference numerals refer to like parts throughout the various views unless otherwise specified. FIG. 1 illustrates a system including an imaging device, an illumination module, and processing logic, in accordance with aspects of the disclosure. FIGS. 2A and 2B illustrate an example imaging device capturing images at different focus depths when an optical element of a MEMS Alvarez tunable lens is moved laterally along an axis, in accordance with aspects of the disclosure. FIGS. 3A and 3B illustrate an example imaging device having a first optical element including a metasurface to provide varying optical power for a MEMS Alvarez tunable lens, in accordance with aspects of the disclosure. FIGS. 4A and 4B illustrate a sideview and a plan view of a combdrive mechanism to laterally shift an optical element along an axis, in accordance with aspects of the disclosure. FIG. 5A illustrates an example image pixel array having an imaging plane defined in a two-dimensional x-y plane, in accordance with aspects of the disclosure. FIG. 5B illustrates an example region that a single MEMS Alvarez tunable lens may be disposed over to focus image light to a plurality of the imaging pixels, in accordance with aspects of the disclosure. FIG. 5C illustrates four MEMS Alvarez tunable lenses configured to focus image light to a plurality of imaging pixels in corresponding regions, in accordance with aspects of the disclosure. FIG. 6 illustrates an example head mounted device that may include an imaging device including MEMS Alvarez tunable lenses, in accordance with aspects of the disclosure. FIG. 7 illustrates a flow chart of an example process of capturing images at varying optical powers with a MEMS Alvarez tunable lens included in an imaging device, in accordance with aspects of the disclosure. DETAILED DESCRIPTION Embodiments of capturing images at varying optical powers are described herein. In the following description, numerous specific details are set forth to provide a thorough understanding of the embodiments. One skilled in the relevant art will recognize, however, that the techniques described herein can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring certain aspects. Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In some implementations of the disclosure, the term “near-eye” may be defined as including an element that is configured to be placed within 50 mm of an eye of a user while a near-eye device is being utilized. Therefore, a “near-eye optical element” or a “near-eye system” would include one or more elements configured to be placed within 50 mm of the eye of the user. In aspects of this disclosure, visible light may be defined as having a wavelength range of approximately 380 nm-700 nm. Non-visible light may be defined as light having wavelengths that are outside the visible light range, such as ultraviolet light and infrared light. Infrared light having a wavelength range of approximately 700 nm-1 mm includes near-infrared light. In aspects of this disclosure, near-infrared light may be defined as having a wavelength range of approximately 700 nm-1.4 μm. In aspects of this disclosure, the term “transparent” may be defined as having greater than 90% transmission of light. In some aspects, the term “transparent” may be defined as a material having greater than 90% transmission of visible light. In implementations of the disclosure, an imaging device includes an image pixel array and a plurality of micro-electro-mechanical systems (MEMS) Alvarez tunable lenses disposed over regions of the imaging pixels. In some implementations, the image pixel array includes single-photon avalanche diodes (SPADs). In an example implem