KR-20260066786-A - Aberration reduction in asymmetric imaging systems

Abstract

The imaging system includes an optical stack, the optical stack including an image sensor and at least one planar lens that is asymmetric with respect to the image sensor or with respect to at least one other optical element within the optical stack. In some embodiments, the asymmetry can be operated to reduce or eliminate keystone distortion.

Inventors

• 매틴슨 프레드릭

Assignees

• 닐 테크놀로지 에이피에스

Dates

Publication Date

20260512

Application Date

20240919

Priority Date

20230920

Claims (16)

1. As an imaging system, It includes an optical stack, and the optical stack is, Image sensor; and An imaging system comprising at least one planar lens that is asymmetric with respect to an image sensor or to at least one other optical element within an optical stack.
2. In claim 1, the imaging system is capable of operating the asymmetry to reduce or eliminate optical aberrations.
3. In claim 1, the imaging system is operable to reduce or eliminate optical off-axis aberrations.
4. In claim 1, the imaging system, wherein the asymmetry is operable to reduce or eliminate keystone distortion.
5. An imaging system according to any one of claims 1 to 4, wherein the asymmetry is provided at least partially by the image sensor being inclined with respect to the optical axis of the imaging system.
6. An imaging system according to any one of claims 1 to 5, wherein the asymmetry is at least partially provided by at least one planar lens being eccentric and/or inclined with respect to the optical axis of the imaging system.
7. An imaging system according to any one of claims 1 to 6, wherein at least one planar lens has an asymmetric phase function.
8. An imaging system according to any one of claims 1 to 7, wherein at least one planar lens is an MOE lens or a DOE lens.
9. An imaging system according to any one of claims 1 to 8, wherein at least one planar lens is a first MOE lens.
10. In claim 9, the optical stack is an imaging system comprising a second MOE lens.
11. An imaging system according to claim 10, further comprising an aperture positioned between the first and second MOE lenses.
12. An imaging system according to any one of claims 1 to 11, comprising an object plane, wherein the object plane is inclined with respect to the optical axis of the optical stack or imaging system.
13. An imaging system according to any one of claims 1 to 11, having a field of view (FOV), wherein the main ray of an axial field point 0F within the FOV is inclined with respect to the optical axis of the optical stack or imaging system.
14. In paragraph 13, at least one planar lens is, A first metasurface having a mixture of symmetric and asymmetric phase profiles; and An imaging system comprising a second metasurface having a symmetric phase profile.
15. An imaging system according to claim 14, further comprising a symmetric aperture disposed between the first and second metasurfaces.
16. An imaging system according to claim 10, comprising an aperture adjacent to the front surface of the first MOE.

Description

Aberration reduction in asymmetric imaging systems The present disclosure relates to reducing aberrations in an asymmetric imaging system. Meta-optical elements (MOEs) and diffractive optical elements (DOEs) are examples of optical elements that employ planar optical technology. MOEs have metasurfaces comprising, for example, dispersed small subwavelength structures (e.g., nanostructures or other meta-atoms) arranged to interact with light in a specific way. Meta-atoms can interact with light waves individually and/or collectively to change the local amplitude, local phase, or both of the incident light waves. Similarly, DOEs have microstructure patterns that change and control the phase of the incident light waves. By altering the microstructure, it is possible for DOEs to generate a range of beam intensity profiles or beam shapes. MOEs or DOEs can be used in optical applications to utilize internal characteristics given by a customized phase function, for example, compared to classical curved refractive lenses. In some use cases of optical imaging systems containing planar optical elements, it may be desirable to provide an inclined object plane. However, such inclination can cause aberrations and distortions. One example is keystone distortion, which refers to the apparent distortion of an image caused by projecting an image onto an inclined surface. For example, distortion of image dimensions can cause square features within the object plane to appear trapezoidal on the image plane. Additionally, the image plane may be inclined, and the resolution and/or focal length may vary asymmetrically across the image plane. In one embodiment, the present disclosure describes an imaging system comprising an optical stack, wherein the optical stack comprises an image sensor and at least one planar lens that is asymmetric with respect to the image sensor or with respect to at least one other optical element within the optical stack. In some embodiments, the asymmetry can be operated to reduce or eliminate optical aberrations. In some embodiments, the asymmetry can be operated to reduce or eliminate optical off-axis aberrations. In some embodiments, the asymmetry can be operated to reduce or eliminate keystone distortion. In some embodiments, asymmetry is provided at least partially by the image sensor being inclined with respect to the optical axis of the imaging system. In some embodiments, asymmetry is provided at least partially by at least one planar lens being eccentric and/or inclined with respect to the optical axis of the imaging system. In some embodiments, at least one planar lens has an asymmetric phase function. In some embodiments, at least one planar lens is an MOE lens or a DOE lens. For example, in some cases, at least one planar lens is a first MOE lens. Additionally, in some cases, the optical stack includes a second MOE lens. In some cases, an aperture is positioned between the first and second MOE lenses. In some cases, an aperture is positioned adjacent to the front surface of the first MOE. In some embodiments, the imaging system includes an object plane, and the object plane is inclined with respect to the optical axis of the lens stack or optical system. In some embodiments, the imaging system has a field of view (FOV), and the principal ray of an on-axis field point 0F within the FOV is inclined with respect to the optical axis of the optical stack or imaging system. In some embodiments, at least one planar lens includes a first metasurface having a mixture of symmetric and asymmetric phase profiles and a second metasurface having a symmetric phase profile. In some cases, a symmetric or asymmetric lens aperture may be placed between the first and second metasurfaces to help reduce distortion. Various advantages can be obtained in some embodiments. For example, in some embodiments, the quality of the image can be improved or enhanced by reducing or eliminating distorted output that may occur due to oblique projection. Other embodiments, features, and advantages will become readily apparent from the following detailed description, the accompanying drawings, and the claims. Figure 1 illustrates an example of a finite conjugate optical imaging system having an inclined object plane. Figures 2a and 2b illustrate an example where the image sensor is tilted with respect to the optical axis. Figure 3 illustrates an example where a planar lens is eccentric with respect to the optical axis of an imaging system. FIGS. 4a, FIGS. 4b, and FIGS. 4c illustrate examples of light footprint diagrams appearing on the first MOE, the second MOE, and the image sensor, respectively, for the setup of FIG. 2a. FIGS. 4d, FIGS. 4e, and FIGS. 4f illustrate other examples of footprint diagrams of light rays appearing in the first MOE, the second MOE, and the image sensor, respectively, for a lens array including a lens having an asymmetric phase profile. Figure 5 illustrates an example of a finite conjugate imaging syste