High bandwidth imaging system

Abstract

A system comprising: one or more elements configured to receive light of different wavelengths within a wavelength range from a light source and separate the received light at different angles in a field of view based on the different wavelengths; an image sensor comprising a sensor surface; a superlens comprising a surface having a plurality of regions, wherein each region is configured to receive light incident within a respective range of incident angles, wherein each respective range of incident angles corresponds to a sub-range of wavelengths of the separated light, and wherein each region is configured to focus light from the respective sub-range of wavelengths on the sensor surface; and an optical aperture having an aperture size configured to limit the respective range of incident angles at each of the plurality of regions of the superlens.

Description

Technical Field

[0001] This specification relates to optical systems and imaging systems that include optical systems. Background Technology

[0002] Superoptical elements (MOEs) are optical elements that employ planar optics techniques. MOEs comprise metasurfaces with distributed superatoms. These superatoms are subwavelength structures (e.g., nanostructures) arranged to interact with light in a specific manner. The superatoms can interact with light waves individually and / or collectively to alter the local amplitude, local phase, or both of the incident light wave. Compared to conventional curved refractive lenses, MOEs can be used, for example, in optical applications to take advantage of their flat surfaces and reduced thickness.

[0003] Planar optical lenses (such as MOEs) can exhibit chromatic aberration when used with high-bandwidth light sources (such as LEDs). Imaging systems incorporating such optics may also exhibit chromatic aberration if it is not addressed, potentially resulting in a limited (e.g., narrow) operating spectral bandwidth (e.g., only a few nanometers). This limitation imposes significant constraints on the selection of scene illumination sources and / or may limit the overall efficiency of these imaging systems, as the modulation transfer function (MTF) can be significantly reduced if the light source bandwidth is wide, for example, wider than that of a typical vertical-cavity surface-emitting laser (VCSEL) or laser. Summary of the Invention

[0004] This specification describes techniques relating to optical systems and imaging systems including optical systems. Generally, one or more aspects of the subject matter described herein may be embodied in a system comprising: one or more elements configured to receive light of different wavelengths within a wavelength range from a light source and to separate the received light at different angles in a field of view based on the different wavelengths; an image sensor including a sensor surface; a superlens including a surface having multiple regions, each region configured to receive light incident within a corresponding incident angle range, each corresponding incident angle range corresponding to a wavelength subrange of the separated light, and each region configured to focus light from the corresponding wavelength subrange onto the sensor surface; and an optical aperture having an aperture size configured to limit the corresponding incident angle range at each of the multiple regions of the superlens.

[0005] These and other aspects may optionally include one or more of the following features.

[0006] Each of the multiple regions may include a corresponding number of superatoms. Each corresponding superatom in the multiple superatoms has a corresponding geometric feature for each of the multiple regions. The corresponding multiple superatoms have one or more of the following for each of the multiple different regions: different shapes, different sizes, or different superatomic spacings.

[0007] One or more elements may include one or more of the following configured to separate light from a light source at different angles in the field of view based on different wavelengths: a bandpass filter, a diffraction grating, a prism, or a super-optical element.

[0008] At least a first region among the plurality of regions may be configured to focus light from a first infrared sub-range. At least a second region among the plurality of regions may be configured to focus light from a second infrared sub-range.

[0009] At least a third region among multiple different regions can be configured to focus light from an infrared sub-range. At least a fourth region among multiple different regions can be configured to focus light from a visible sub-range.

[0010] At least a fifth region among the multiple regions can be configured to focus light from a first visible sub-range. At least a sixth region among the multiple different regions can be configured to focus light from a second visible sub-range.

[0011] Light of different wavelengths may include light with a wavelength range of 50 nm or above, or light with a wavelength range of 100 nm or above. Light of different wavelengths may include light with a wavelength range of approximately 920 nm to 960 nm.

[0012] Each of the multiple different regions can be configured to focus light incident with a corresponding incident angle range onto the sensor surface with substantially the same optical resolution.

[0013] A system may further include one or more light sources configured to produce light of different wavelengths within a wavelength range.

[0014] Each of the multiple regions is configured to focus light from a wavelength subrange of about 10 nm or less, 5 nm or less, or 2 nm or less.

[0015] Typically, one or more aspects of the subject matter described in this specification may also be embodied in a system comprising: one or more elements configured to receive light of different wavelengths within a wavelength range from a light source and to separate the received light at different angles in a field of view based on the different wavelengths; an image sensor including a sensor surface; a superlens including a surface having a plurality of superatoms, wherein the superlens is configured to receive light incident at a plurality of incident angles within a range of incident angles, wherein each corresponding incident angle corresponds to a wavelength of the separated light, and wherein corresponding geometric features of the plurality of superatoms vary as a continuous function on the superlens with respect to the wavelength of the separated light incident at the corresponding incident angle; and an optical aperture having an aperture size configured to limit a corresponding range of incident angles at each of a plurality of regions of the superlens.

[0016] These and other aspects may optionally include one or more of the following features.

[0017] The corresponding geometric features include one or more of the following: different shapes, different sizes, or different superatomic spacings.

[0018] One or more elements may include one or more of the following configured to separate light from a light source at different angles in the field of view based on different wavelengths: a bandpass filter, a diffraction grating, a prism, or a super-optical element.

[0019] Light of different wavelengths may include light with a wavelength range of 50 nm or above, or light with a wavelength range of 100 nm or above. Light of different wavelengths may include light with a wavelength range of approximately 920 nm to 960 nm.

[0020] A system may further include one or more light sources configured to produce light of different wavelengths within a wavelength range.

[0021] Specific embodiments of the subject matter described in this specification can achieve one or more of the following advantages. MOEs with reduced chromatic aberration, such as superlenses, can be provided. In particular, specific regions of the MOE can be adapted to a predetermined wavelength range. The MOEs described in this invention can be integrated into an imaging system to reduce chromatic aberration. The imaging system may include one or more optical elements configured to spatially separate the wavelengths of one or more light sources within the field of view (FOV) of the imaging system. Each portion of the field of view may correspond to a local region of one or more MOEs integrated into the imaging system, and each local region of the one or more MOEs can be adapted to a predetermined wavelength range.

[0022] The concepts described in this specification can help enhance the operating spectral bandwidth of imaging systems and make the systems compatible with the bandwidth of standard light sources (e.g., light-emitting diodes, LEDs). This can improve the overall performance, quality, and / or efficiency of imaging systems with different operating spectral bandwidths. The systems described in this invention can also be integrated into other types of optical systems.

[0023] Details of one or more embodiments of the subject matter described in this specification are set forth in the accompanying drawings and the following description. Other features, aspects, and advantages of the invention will be apparent from the description, the drawings, and the claims. Attached Figure Description

[0024] Figure 1 An example of an imaging system including an optical system is shown.

[0025] Figure 2A A cross-sectional view of an MOE example is shown.

[0026] Figure 2B A top view of an MOE example is shown.

[0027] Figure 3 A cross-sectional view of an MOE example is shown.

[0028] Figure 4 A cross-sectional view of an MOE example is shown.

[0029] Similar reference numerals and names in the various figures denote similar elements. Specific Implementation

[0030] The optical materials of lenses typically exhibit some degree of wavelength dispersion because the refractive index of the lens material depends, at least to some extent, on the wavelength of light propagating through the medium. This phenomenon arises because the phase velocity of a wave depends on its frequency. The result of dispersion is that the angle of refraction varies with wavelength. Planar optics based on diffraction, such as MOEs, introduce significantly greater dispersion due to wavelength dependence. These dispersion effects affect image quality and introduce chromatic aberration.

[0031] Figure 1 An example of an imaging system 100 including an optical system is shown. The imaging system 100 may include a transmitter 105 and a receiver (e.g., a camera) 110.

[0032] The transmitter 105 may include one or more light sources 115 (e.g., light sources), configured to generate light of different wavelengths within a wavelength range. Depending on the specific application, the wavelength may be, for example, in the visible light range (approximately 400 nm to 700 nm) or the infrared range (approximately 700 nm to 1 mm), such as in the near-infrared range (approximately 700 nm to 1400 nm) or the short-wave infrared range (approximately 900 nm to 3000 nm). In some examples, the light source may provide light in the infrared (e.g., near-infrared) and / or visible light ranges.

[0033] In some examples, the light source includes conventional light sources, such as LEDs. In some examples, the wavelength range is 50 nm or higher, or 100 nm or higher. In some examples, the wavelength range is approximately 920 nm to 960 nm. In other examples, the light source includes a VCSEL array. In some examples, other types of light-emitting or reflective devices may be used.

[0034] Imaging system 100 may include one or more elements 120, configured to receive light of different wavelengths within a wavelength range provided by light source 115, and to separate the received light at different angles in the field of view based on different wavelengths 121, 122, 123. Figure 1 In the example, each received ray has a different wavelength 121, 122, 123, and is separated at different angles in the field of view based on the corresponding wavelength. One or more elements 120 may include one or more of the following configured to separate light from light source 115 at different angles in the field of view based on different wavelengths: such as a bandpass filter, a diffraction grating, a prism, a diffractive optics element, an MOE, or any other optical element.

[0035] The receiver 110 (e.g., a camera) may include an image sensor 130 having a sensor surface 131. An MOE 140 (e.g., a superlens) may be configured to focus light onto the sensor surface 131. The superlens may include a surface, such as a metasurface disposed on an optically transparent or at least partially transparent substrate (e.g., glass, plastic, or polymer material). The substrate may provide mechanical support for the metasurface.

[0036] The imaging system may include an optical aperture 150, which limits the angular range of light entering each point in the super-optical element 140. For example, in Figure 1 In this case, the aperture size restricts the light rays incident on point 149, thus limiting the field of view of point 149 to α. For example, the aperture may be included in aperture layer 160, which includes a hole (e.g., a circular opening) in the light-shielding material as aperture 150.

[0037] Since each part of the FOV corresponds to a local area of ​​the MOE140, specific areas of the super-optical element can be adapted to the range of wavelengths it is exposed to.

[0038] Aperture size can be chosen based on desired image quality (e.g., MTF or resolution) and / or the application of the imaging system. If the aperture is large, light from a wide angular range (and therefore a wide wavelength range) will enter the corresponding area of ​​the sensor. This reduces the benefits in reducing chromatic aberration. On the other hand, if the aperture is small, light from a very narrow angular range will reach the corresponding area of ​​the sensor, allowing each area to be adapted to a very specific wavelength range, thus significantly reducing chromatic aberration. However, reducing the aperture size (typically measured as the focal length divided by the inverse F-number of the aperture diameter, F#) reduces the amount of light reaching the sensor, making image acquisition challenging in low-light conditions.

[0039] The super-optical element 140 may include a surface (e.g., a metasurface) comprising multiple regions, such as Figure 1 Regions 141, 142, and 143 are shown. Each region can be configured to receive light incident within a corresponding incident angle range. Each corresponding incident angle range can correspond to a wavelength sub-range of light separated by one or more elements 120. For example, region 141 can receive light of wavelength 121, such as light 151. For example, region 142 can receive light of wavelength 122, such as light 152. For example, region 143 can receive light of wavelength 123, such as light 153. Each region 141, 142, and 143 is configured to focus light from the corresponding wavelength sub-range onto the sensor surface. Because each specific region in the super-optical element 140 is adapted to its exposed wavelength range, chromatic aberration can be reduced.

[0040] Figure 2A A cross-sectional view of an example MOE 240 is shown. Figure 2B A top view of the MOE 240 is shown. In this example, the MOE has a circular shape, but other shapes are also possible. For example, an ellipse or other polygonal or irregular shapes are possible.

[0041] MOE 240 can be a superlens configured to receive light from one or more light sources. For example, it can receive light emitted from an LED within a wavelength range of 900 ± 50 nm (850 nm to 950 nm). In other examples, one or more light sources can emit light within a wavelength range of 940 ± 20 nm (920 nm to 960 nm). Light from one or more light sources can be separated at different angles based on wavelength. For example, optical elements (such as element 120) can be used to separate light of different wavelengths at different angles in the field of view.

[0042] exist Figure 2A and Figure 2BIn the example, the first wavelength range The light primarily enters the MOE 240 at high incident angles. In this example, the second wavelength range... The light primarily enters the MOE 240 at a low incident angle. Since each part of the FOV corresponds to a local region of the MOE 140, specific regions of the MOE 140 can be adapted to the range of wavelengths it is exposed to.

[0043] For example, MOE 240 can be divided into two regions, 141 and 142, each corresponding to a specific wavelength sub-range. For instance, if the light source emits light in the wavelength range of 900 ± 50 nm (850 nm to 950 nm), region 141 can be adapted to the focusing wavelength sub-range. The light covers a sub-range of 100 nm, and region 142 is adaptable to the focusing wavelength sub-range. The light also covers a sub-range of 100 nm. In other examples, the MOE240 can be divided into even more regions to improve wavelength specificity. For example, each region of the MOE can be adapted to focus wavelength sub-ranges of 50 nm or less, 10 nm or less, 5 nm or less, or 2 nm or less.

[0044] In some examples, at least one region may be configured to focus light from an infrared sub-range, while another region may be configured to focus light from another infrared sub-range. Additionally or alternatively, in some examples, at least one region may be configured to focus light from an infrared sub-range, while another region may be configured to focus light from a visible sub-range. Additionally or alternatively, in some examples, at least one region may be configured to focus light from a first visible sub-range, while at least one region may be configured to focus light from a second visible sub-range.

[0045] Each of the plurality of regions 141, 142 includes a corresponding plurality of superatoms (e.g., superatoms 261, 262 in region 141 and superatoms 271, 272 in region 142), wherein each corresponding superatom among the plurality of superatoms has a corresponding geometric feature for each of the plurality of regions. For example, the corresponding plurality of superatoms for each of the plurality of different regions have one or more of the following: different widths, different heights, or different interatomic spacings. Figure 2A In the example, the height of the superatom varies discretely from one region to another, as shown in envelope 280. Figure 2A In the example, the width and spacing of the superatoms are also different in each region and vary discretely from one region to another.

[0046] Each of the multiple distinct regions can be configured to focus light incident within its corresponding incident angle range (e.g., corresponding to a corresponding wavelength sub-range) onto the sensor surface with substantially the same quality or resolution. The geometries of the superatoms in each specific region can be selected such that the performance is substantially identical for each corresponding wavelength sub-range. Even with high-bandwidth light sources, MTF, image quality, or resolution can still be high.

[0047] For example, an optimization method for the phase function of a superlens can be performed to determine the geometric characteristics of the superatoms in each region of the superlens, such as one or more of the following: shape (e.g., width and / or height), size, position, or superatomic spacing, which can be adapted to wavelength subranges and quality or resolution requirements.

[0048] Figure 3 A cross-sectional view of an example MOE 340 is shown. The MOE 340 can be a superlens for receiving light from one or more light sources (not shown). In this example, the MOE has a circular shape, but other shapes are also possible. For example, it can receive light emitted from an LED within a wavelength range of 900 ± 50 nm. Light from one or more light sources can be separated at different angles based on wavelength. For example, optical elements (such as element 120) can be used to separate light of different wavelengths at different angles within the field of view (FOV).

[0049] In this example, the MOE 340 is divided into five regions: 341, 342, 343, 344, and 345, each configured for a different wavelength sub-range, such as a wavelength range of 900 ± 50 nm. In other examples, the MOE 340 can be divided into more or fewer regions to increase or decrease wavelength specificity and / or cover other wavelength ranges. For example, the wavelength range of 940 ± 20 nm can be covered by eight regions, each sub-range of 5 nm, which is a typical wavelength range that a superlens can handle, while still providing the expected image quality for each range.

[0050] Although not in Figure 3 As shown, each of the multiple regions 341, 342, 343, 344, and 345 comprises a corresponding plurality of superatoms. Each corresponding superatom of the plurality of superatoms has a corresponding geometric feature of each of the multiple regions. For example, the corresponding plurality of superatoms have one or more of the following for each of the multiple different regions: different widths, different heights, or different interatomic spacings.

[0051] Each of the multiple distinct regions can be configured to focus light incident within a corresponding incident angle range (e.g., corresponding to a corresponding wavelength sub-range) onto the sensor surface with substantially the same quality or resolution. The geometry of the superatoms in each particular region can be selected such that the performance is substantially the same for each corresponding wavelength sub-range.

[0052] For example, the phase function of each region can be optimized, and an optimization method for the phase function of each region can be performed to determine geometric features that are adapted to the wavelength subrange and quality or resolution requirements.

[0053] Figure 4 A cross-sectional view of an example MOE is shown. In this example, MOE 440 has a circular shape, but other shapes are also possible. MOE 440 can be a superlens for receiving illumination from one or more light sources. For example, it can receive light emitted from an LED within a predetermined wavelength range. Light from one or more light sources can be separated at different angles based on wavelength; for example, optical elements (such as element 120) can be used to separate light of different wavelengths at different angles within the field of view (FOV).

[0054] However, light of different wavelengths is not entirely localized. The intensity of each corresponding wavelength varies with the angle of incidence, exhibiting intensity peaks at some angles and intensity troughs at others. Rather than assuming that each part of the FOV corresponds to a very localized region of the super-optical element 140 and dividing the MOE into different regions with discretely varying geometry from one region to another, such as MOE 240, in the case of MOE 340, one or more geometric features of the superatom vary as a continuous function on the superlens. For example, it can vary as a continuous function of the wavelength of the separated light incident at the corresponding angle of incidence, such as the dominant wavelength of the separated light at the corresponding angle of incidence.

[0055] An optimization method for the phase function of a superlens can be performed to determine the geometric features of the superatoms. For example, the phase function of a superlens with multiple regions can be optimized to determine the geometric features of the superatoms in each region of the superlens (e.g., one or more of the following: shape, size, position, or superatomic spacing, etc.), which can be adapted to a wavelength range and quality or resolution requirements. Interpolation of the geometric feature results between regions can then be performed to obtain a continuous function of one or more geometric features on the superlens. The geometric features can be one or more of the following: shape (e.g., width, height), size, position, or superatomic spacing, etc. Figure 4 In the example, envelope 480 shows the height of the superatom as a continuous function of wavelength or incident angle. All wavelengths within the wavelength range can be focused onto the sensor surface with substantially the same quality or resolution.

[0056] Although this specification includes many specific details, these should not be construed as limiting the scope of the disclosure or the possible scope of the claims, but rather as describing features of particular embodiments. Certain features described in the context of separate embodiments in this specification may also be combined in the same embodiment. Conversely, various features described in the context of a single embodiment may also be combined in multiple separate embodiments or in any suitable sub-combination. Various modifications can be made to the above examples. Therefore, other embodiments are also within the scope of the claims.

Claims

1. A system comprising:    One or more elements are configured to receive light of different wavelengths within a wavelength range from a light source and to separate the received light at different angles in the field of view based on the different wavelengths.    Image sensor, including sensor surface;    A superlens includes a surface having multiple regions, each region being configured to receive light incident within a corresponding incident angle range, each corresponding incident angle range corresponding to a wavelength sub-range of split light, and each region being configured to focus light from the corresponding wavelength sub-range onto the sensor surface. as well as An optical aperture having an aperture size configured to limit the corresponding range of incident angles in each of the plurality of regions of the superlens.

2. The system according to claim 1, wherein Each of the plurality of regions includes a corresponding plurality of superatoms, wherein each of the plurality of superatoms has a corresponding geometric feature for each of the plurality of regions.

3. The system of claim 2, wherein the respective plurality of superatoms have one or more of the following for each of the plurality of different regions: different shapes, different sizes, or different superatomic spacings.

4. The system of claim 1, wherein the one or more elements include one or more of the following configured to separate the light from the light source at different angles in the field of view based on the different wavelengths: a bandpass filter, a diffraction grating, a prism, a diffractive optical element, or a super-optical element.

5. The system of claim 1, wherein at least a first region of the plurality of regions is configured to focus light from a first infrared sub-range, and wherein at least a second region of the plurality of regions is configured to focus light from a second infrared sub-range.

6. The system according to any of the preceding claims, wherein at least a third region of the plurality of different regions is configured to focus light from an infrared subrange, and wherein at least a fourth region of the plurality of different regions is configured to focus light from a visible subrange.

7. The system according to any of the preceding claims, wherein at least a fifth region of the plurality of regions is configured to focus light from a first visible subrange, and wherein at least a sixth region of the plurality of different regions is configured to focus light from a second visible subrange.

8. The system of claim 1, wherein the light of different wavelengths includes light with a wavelength range of 50 nm or above, or 100 nm or above.

9. The system of claim 1, wherein the light of different wavelengths includes light with a wavelength range of about 920 nm to 960 nm.

10. The system of claim 1, wherein each of the plurality of different regions is configured to focus light incident within the respective incident angle range onto the sensor surface with substantially the same optical resolution.

11. The system according to any of the preceding claims further includes one or more light sources configured to generate light of different wavelengths within the wavelength range.

12. The system of claim 1, wherein each of the plurality of regions is configured to focus light from a wavelength subrange of about 10 nm or less, 5 nm or less, or 2 nm or less.

13. A system comprising:    One or more elements are configured to receive light of different wavelengths within a wavelength range from a light source and to separate the received light at different angles in the field of view based on the different wavelengths.    Image sensor, including sensor surface;    A superlens includes a surface having a plurality of superatoms, wherein the superlens is configured to receive light incident at a plurality of incident angles within a range of incident angles, wherein each corresponding incident angle corresponds to a wavelength of the separated light, and wherein the corresponding geometric features of the plurality of superatoms vary as a continuous function on the superlens with respect to the wavelength of the separated light incident at the corresponding incident angle. as well as An optical aperture having an aperture size configured to limit a corresponding range of incident angles in each of the plurality of regions of the superlens.

14. The system of claim 13, wherein the corresponding geometric features include one or more of the following: different shapes, different sizes, or different superatomic spacings.

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