WO2025258002A1 - Élément d'imagerie et dispositif d'imagerie - Google Patents

Élément d'imagerie et dispositif d'imagerie

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Publication number
WO2025258002A1
WO2025258002A1 PCT/JP2024/021424 JP2024021424W WO2025258002A1 WO 2025258002 A1 WO2025258002 A1 WO 2025258002A1 JP 2024021424 W JP2024021424 W JP 2024021424W WO 2025258002 A1 WO2025258002 A1 WO 2025258002A1
Authority
WO
WIPO (PCT)
Prior art keywords
wavelength
light
polarization
axis
array
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/JP2024/021424
Other languages
English (en)
Japanese (ja)
Inventor
将司 宮田
俊和 橋本
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NTT Inc
NTT Inc USA
Original Assignee
Nippon Telegraph and Telephone Corp
NTT Inc USA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Telegraph and Telephone Corp, NTT Inc USA filed Critical Nippon Telegraph and Telephone Corp
Priority to PCT/JP2024/021424 priority Critical patent/WO2025258002A1/fr
Publication of WO2025258002A1 publication Critical patent/WO2025258002A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N25/00—Circuitry of solid-state image sensors [SSIS]; Control thereof
    • H04N25/70—SSIS architectures; Circuits associated therewith

Definitions

  • polarized color imaging devices that make it possible to acquire polarized color images, which are images that contain polarization information in addition to color information.
  • Conventional polarized color imaging devices acquire polarization and color information of the subject by stacking microlenses, light-absorbing polarizing filters, and color filters on the pixels.
  • FIG. 1 is a side view showing a schematic configuration of an imaging device according to an embodiment.
  • FIG. 2 is a diagram schematically illustrating an example of a part of a cross section of a pixel array and a polarization wavelength separation array of an image sensor according to an embodiment.
  • FIG. 3 is a diagram schematically illustrating an example of a plane of a polarization wavelength separation lens in a polarization wavelength separation lens array of an image sensor according to an embodiment.
  • FIG. 4 is a diagram schematically illustrating an example of the polarization separation and wavelength separation characteristics of the polarization wavelength separation lens of the image sensor according to the embodiment.
  • FIG. 5 is a plan view showing an example of a microstructure constituting the polarized light wavelength separation lens according to the first embodiment.
  • FIG. 13 is a diagram showing the calculation results of the phase delay characteristics of the microstructures shown in FIGS.
  • FIG. 14 is a diagram showing the calculation results of the phase delay characteristics of a microstructure obtained by rotating the axis of symmetry of the microstructures shown in FIGS. 8 and 9 by 45°.
  • FIG. 15 is a diagram showing the calculation results of the phase delay characteristics of a microstructure obtained by rotating the axis of symmetry of the microstructure shown in FIGS. 10 and 11 by 45°.
  • FIG. 16 is a plan view schematically showing another example of the polarization wavelength separation lens according to the first embodiment.
  • FIG. 17 is a diagram schematically illustrating a part of a cross section taken along line XVII-XVII shown in FIG. FIG.
  • FIG. 23 is a diagram illustrating an example of a light intensity distribution on a pixel array when light having different polarization states and combinations of wavelengths is incident perpendicularly on the image sensor according to the first embodiment.
  • FIG. 24 is a diagram illustrating an example of a light intensity distribution on a pixel array when light having different polarization states and combinations of wavelengths is incident perpendicularly on the image sensor according to the first embodiment.
  • FIG. 25 is a diagram showing another example of the top surface shape of the microstructure in the polarization wavelength separation lens according to the first embodiment.
  • FIG. 26 is a diagram schematically illustrating a part of a cross section of another configuration example of the imaging element according to the first embodiment.
  • FIG. 33 is a diagram schematically illustrating a part of a cross section taken along line XXXIII-XXXIII shown in FIG. 32.
  • FIG. 34 is a diagram for explaining the angle of incidence of light incident on the imaging element shown in FIGS. 32 and 33.
  • FIG. 35 is a plan view schematically illustrating another example of the imaging element according to the first embodiment.
  • 36 is a diagram schematically showing a part of a cross section taken along line XXXVI-XXXVI shown in FIG. 35.
  • FIG. 37 is a diagram schematically illustrating a part of a cross section of an imaging element according to the second embodiment.
  • FIG. 38 is a diagram schematically illustrating a part of a cross section of an imaging element according to the third embodiment.
  • FIG. 39 is a diagram schematically illustrating a part of a cross section of an imaging element according to the fourth embodiment.
  • FIG. 1 is a side view showing a schematic configuration of an image pickup apparatus according to an embodiment of the present invention.
  • the imaging device 1 includes a lens optical system 2, an imaging element 3, and a signal processing unit 4.
  • the signal processing unit 4 processes the electrical signal output from the imaging element 3 to generate an image signal.
  • the lens optical system 2 is an example of an imaging optical system, and forms an optical image on the imaging surface of the imaging element 3.
  • light such as natural light or illumination light
  • the lens optical system 2 When light such as natural light or illumination light is irradiated onto an object, the light reflected, scattered, or transmitted by the object, or the light emitted from the object, is used by the lens optical system 2 to form an optical image on the imaging surface of the imaging element 3.
  • the lens optical system 2 is composed of a lens group consisting of multiple lenses lined up along the optical axis to correct various optical aberrations, but in Figure 1 it is shown as a single lens for simplicity.
  • the image sensor 3 is an image sensor that uses a metasurface, and outputs an electrical signal containing information for each pixel corresponding to the polarization direction and wavelength component based on the light incident on the imaging surface by the lens optical system 2.
  • the signal processing unit 4 processes the electrical signal output from the image sensor 3 to generate an image signal, and outputs the generated image signal to the outside.
  • the image signal is, for example, a polarized color image signal that includes polarization information and wavelength information.
  • the polarized color image signal is an image signal for each combination of the polarization direction and wavelength component to be separated, but is not limited to this example.
  • the imaging device 1 may include well-known components such as an infrared-blocking optical filter, an electronic shutter, a viewfinder, a power source (battery), and a flashlight, but a description of these is omitted as they are not particularly necessary for understanding the present invention. Furthermore, the above configuration is merely an example, and in embodiments, well-known elements can be used in appropriate combinations as components other than the lens optical system 2, the imaging element 3, and the signal processing unit 4.
  • FIG. 2 is a diagram schematically illustrating an example of a part of a cross section of the pixel array and the polarization wavelength separation array of the image sensor 3 according to the embodiment.
  • the image sensor 3 has a transparent substrate 10, a polarized wavelength separation lens array 20, a transparent layer 30, and a pixel array 40.
  • the transparent layer 30, the polarized wavelength separation lens array 20, and the transparent substrate 10 are stacked in this order on the pixel array 40.
  • the polarized wavelength separation lens array 20 is an example of a spectroscopic element array.
  • Figure 2 corresponds to a cross-sectional view taken along line II-II in Figure 3, which will be described later.
  • the transparent substrate 10 is, for example, a low-refractive-index transparent substrate made of a material such as SiO2 , but is not limited to this example.
  • the polarized wavelength separation lens array 20 includes a plurality of polarized wavelength separation lenses 21 arranged in a two-dimensional array on the bottom surface of the transparent substrate 10.
  • Fig. 2 shows a portion of one of the plurality of polarized wavelength separation lenses 21.
  • the polarized wavelength separation lens 21 is an example of a spectroscopic element.
  • Each polarized wavelength separation lens 21 has a periodic arrangement of multiple microstructures that separate incident light according to its polarization direction and wavelength components, and focus the incident light at different positions on the pixel array 40 according to the polarization direction and wavelength components of the incident light. This allows the polarized wavelength separation lens 21 to focus light from the object to be imaged O as incident light at different pixels on the pixel array 40 according to its polarization direction and wavelength components.
  • the transparent layer 30 is an air layer or a layer made of SiO2 , but is not limited to these examples.
  • the transparent layer 30 may be made of any material as long as it has a lower refractive index than the material of the polarized wavelength separation lens 21 and has low loss with respect to the wavelength of the incident light, and may be made of a material such as glass, or may be a transparent layer having a layered structure made of multiple materials. Note that in FIG. 2, an air layer is shown as the transparent layer 30.
  • the pixel array 40 has a plurality of pixels 41, each containing a photoelectric conversion element arranged in a two-dimensional array, and a wiring layer 42 that transmits electrical signals generated by each pixel 41 to the signal processing unit 4 and transmits control signals to each pixel 41 to control the operation of the pixels 41.
  • an xyz Cartesian coordinate system is set in several drawings, including Figure 2.
  • the direction perpendicular to the pixel array surface of the pixel array 40 is the z-axis
  • the array direction of the four pixels 41 shown in Figure 2 is the x-axis
  • the direction perpendicular to the x-axis is the y-axis.
  • the pixel array surface is the xy plane, which is the two-dimensional array direction of the pixels 41 in the pixel array 40.
  • an angle ⁇ is set with respect to the x-axis on the xy plane, which is parallel to the pixel array surface of the pixel array 40.
  • FIG. 3 is a diagram schematically illustrating an example of a plane of a polarization wavelength separation lens 21 in a polarization wavelength separation lens array 20 of an image sensor 3 according to an embodiment. While one polarization wavelength separation lens 21 is shown in FIG. 3, in the polarization wavelength separation lens array 20, multiple polarization wavelength separation lenses 21 are arranged in a two-dimensional array in the x and y directions.
  • the polarization wavelength separation lens 21 has a periodic arrangement of a plurality of microstructures 211.
  • the plurality of microstructures 211 separate the incident light according to the polarization direction and wavelength components, and focus the incident light at different positions on the pixel array 40 according to the polarization direction and wavelength components of the incident light.
  • the microstructures 211 are formed from a material such as SiN or TiO2 that has a refractive index higher than that of the transparent layer 30.
  • the period P in the periodic arrangement of the microstructures 211 is shorter than the wavelength of the transmitted light, thereby suppressing unnecessary diffracted light.
  • the microstructures 211 in the polarized wavelength separation lens 21 shown in FIG. 3 have an axis of linear symmetry and an incident surface, onto which incident light is incident, that has a shape with a different length in the direction of the axis of linear symmetry and in the direction perpendicular to the axis of linear symmetry.
  • each microstructure 211 has an axis of linear symmetry that is parallel to the x-axis or y-axis, or parallel to an axis tilted 45° from the x-axis or y-axis.
  • the polarized wavelength separation lens 21 includes microstructures 211 that have an axis of linear symmetry that is parallel to the x-axis or y-axis, and microstructures 211 that have an axis of linear symmetry that is parallel to an axis tilted 45° from the x-axis or y-axis.
  • the shape of the incident surface is, for example, a rectangle with a longitudinal direction and a lateral direction, a cross with a longitudinal direction and a lateral direction, or an ellipse with a longitudinal direction and a lateral direction, and has a shape with a different length in the direction of the axis of linear symmetry and in the direction perpendicular to the axis of linear symmetry.
  • the axis of linear symmetry and the structure of the microstructure 211 are modulated depending on the position on the polarized wavelength separation lens 21, which allows the polarized wavelength separation lens 21 to more appropriately focus incident light onto pixels 41 at different positions on the pixel array 40 depending on the polarization direction and wavelength components of the incident light.
  • the structure of the microstructure 211 is modulated by modulating the area of the top surface of the microstructure 211 onto which incident light is incident, the shape of the microstructure 211, the volume of the microstructure 211, etc.
  • the structure of the microstructure 211 is modulated so that the phase delay characteristics of the microstructure 211 are modulated.
  • the structure of all of the multiple microstructures 211 is modulated, but this is not limited to this example, and the structure may be modulated only for some of the multiple microstructures 211.
  • multiple microstructures 211 are arranged in both the x and y directions, and the axis of linear symmetry of a microstructure 211 differs by 45° from the axis of linear symmetry of adjacent microstructures 211 in the x and y directions, which are the arrangement directions of the periodic array. This allows the polarized wavelength separation lens 21 to vary the polarization direction in small incident area units, and to more appropriately focus incident light on pixels 41 at different positions on the pixel array 40 depending on the polarization direction and wavelength components of the incident light.
  • the polarization directions separated by the polarized wavelength separation lens 21 may be, for example, four or more, and the wavelength components separated by the polarized wavelength separation lens 21 may be, for example, two or more, but are not limited to these examples.
  • the wavelength components separated by the polarized wavelength separation lens 21 are, for example, red (R) wavelength components, green (G) wavelength components, blue (B) wavelength components, and near-infrared light (N) wavelength components.
  • Figure 4 is a diagram showing an example of the polarization separation and wavelength separation characteristics of the polarization wavelength separation lens 21 of the image sensor 3 according to the embodiment.
  • incident light which has been spatially separated into four wavelength components in each of the four polarization directions by the polarized wavelength separation lens 21, is received by 16 pixels 41.
  • the pixel array 40 is formed with 16 pixels 41 as a unit structure for each polarized wavelength separation lens 21.
  • R indicates that the wavelength component is red (R)
  • G indicates that the wavelength component is green (G)
  • B indicates that the wavelength component is blue (B)
  • N indicates that the wavelength component is near-infrared light (N).
  • the polarization direction and wavelength components separated by the polarized wavelength separation lens 21 are not limited to the example shown in FIG. 4, and the polarization direction and wavelength components separated can be changed as desired depending on the configuration of the polarized wavelength separation lens 21. Furthermore, the arrangement, shape, and size of the pixels 41 are not limited to the example shown in FIG. 4.
  • the image sensor 3 has a polarized wavelength separation lens 21 in which dispersive elements, each having a periodic arrangement of microstructures 211 that focus incident light to different positions on the pixel array 40 depending on the polarization direction and wavelength components of the incident light, are arranged in a two-dimensional array.
  • the period P of the periodic arrangement of the microstructures 211 is shorter than the wavelength of the transmitted light.
  • microstructures 211 have a surface on which the incident light is incident, which has an axis of linear symmetry and a shape whose length varies in the direction of the axis of linear symmetry and in the direction perpendicular to the axis of linear symmetry, and the axis of linear symmetry and structure are modulated depending on the position on the polarized wavelength separation lens 21. This allows the image sensor 3 to separate the polarization direction and wavelength of incident light without using color filters or polarizing filters, thereby reducing the number of parts and contributing to lower costs.
  • the image sensor 3 does not use color filters or polarizing filters, it is possible to maximize light utilization efficiency and improve imaging sensitivity compared to conventional image sensors that use color filters and polarizing filters. Furthermore, because the above functions can be achieved using only a single layer of microstructure elements that can be easily fabricated, it is possible to provide an image sensor 3 with superior productivity compared to conventional technology.
  • the imaging device 1 according to the first embodiment has a lens optical system 2, an imaging element 3, and a signal processing unit 4.
  • the imaging element 3 according to the first embodiment also has a transparent substrate 10, a polarization wavelength separation lens array 20, a transparent layer 30, and a pixel array 40, similar to the configuration shown in FIG.
  • the incident light that enters the image sensor 3 is separated into its polarization direction and wavelength components by the polarizing wavelength separation lens 21, and as described above, the separated light is focused at different positions on the pixel array 40 depending on the combination of polarization direction and wavelength components.
  • each unit structure outputs 16 electrical signals corresponding to different combinations of polarization direction and wavelength components.
  • the signal processing unit 4 performs image processing such as demosaic processing, color correction processing based on matrix operations, and polarization correction processing based on matrix operations on the 16 electrical signals for each unit structure output from the pixel array 40, to generate a polarized color image according to the polarization direction and wavelength components, and outputs a signal of the generated polarized color image.
  • image processing such as demosaic processing, color correction processing based on matrix operations, and polarization correction processing based on matrix operations on the 16 electrical signals for each unit structure output from the pixel array 40, to generate a polarized color image according to the polarization direction and wavelength components, and outputs a signal of the generated polarized color image.
  • a polarized color image is, for example, an image obtained by multiplying the number of polarization directions to be separated by the number of wavelength components to be separated, and is an image for each combination of polarization direction and wavelength component to be separated, but is not limited to this example.
  • the above-mentioned unit structures form an array on a two-dimensional plane, so the signal processing unit 4 can obtain two-dimensional spatial information about the polarization component information and wavelength component information of the object imaged on the image sensor 3.
  • the polarization wavelength separation lens 21 includes a periodic arrangement of a plurality of microstructures 211.
  • Each microstructure 211 is a structure formed of a plurality of or a single columnar shape, but may also be a structure composed of a plurality of or a single hole shape, or a structure composed of a columnar shape and a hole shape.
  • the spacing between the microstructures 211 is shorter than the wavelength of the light to be received, i.e., shorter than the wavelength of the light that is the target for receiving in the pixel array 40.
  • the spacing between the microstructures 211 is set to less than ⁇ min /n 0 , where n 0 is the refractive index of the transparent layer on the transmission side.
  • the spacing between the microstructures 211 is the above-mentioned array period P, and this array period P is defined as P ⁇ min /n 0 .
  • FIG. 5 is a plan view showing an example of the microstructures 211 that form the polarization wavelength separation lens 21 according to embodiment 1.
  • Figures 6 and 7 are side views of the microstructures 211 that form the polarization wavelength separation lens 21 according to embodiment 1.
  • the microstructures 211 shown in Figures 5 to 7 are structures formed in a columnar shape.
  • the polarization wavelength separation lens 21 is configured by arranging a plurality of columnar microstructures 211 as shown in Figures 5 to 7.
  • Each microstructure 211 is formed from a material having a refractive index n1 that is higher than the refractive index n0 of the material surrounding the structure or the space, and the thickness of the structure, i.e., the length h in the z-axis direction, is constant.
  • the top and bottom surfaces of the microstructure 211 are rectangular with a width w1 in the x-axis direction and a width w2 in the y-axis direction.
  • the microstructure 211 functions as an optical waveguide that confines and propagates light within the structure due to the difference in refractive index between the structure and the material or space surrounding it.
  • the microstructure 211 e.g., the top surface
  • the light incident on the microstructure 211 propagates while being tightly confined within the structure.
  • the light incident on the microstructure 211 propagates while being subjected to a phase delay effect determined by the effective refractive index n eff of the optical waveguide, and is finally output from the other side of the structure (e.g., the bottom surface).
  • the amount of phase delay ⁇ caused by the microstructure 211 is expressed by Equation (1), where ⁇ is the wavelength of light in a vacuum.
  • the phase delay amount ⁇ by the microstructure 211 varies depending on the wavelength ⁇ of light, and therefore, it is possible to impart different phase delay amounts to light depending on the wavelength region in the same microstructure 211.
  • the refractive index n eff also varies depending on the wavelength ⁇ of light, and the degree of the refractive index n eff is largely dependent on the dimensions of the top surface shape of the microstructure 211. Therefore, by using microstructures 211 with various top surface shapes, it is possible to set various combinations of phase delay amounts ⁇ according to the wavelength ⁇ of light.
  • the refractive index n eff is a function of the structural dimensions, and it is known that strong polarization dependency occurs depending on the structural shape.
  • the structural cross section is made to be rectangular as shown in Figures 6 and 7, different refractive indices n eff can be independently given to orthogonal incident polarized light.
  • phase delay amount of the microstructure 211 for the polarization component in the horizontal direction (x-axis direction) in Fig. 5 is denoted by ⁇ h
  • phase delay amount of the microstructure 211 for the polarization component in the vertical direction (y-axis direction) in Fig. 5 is denoted by ⁇ v
  • effective refractive index of the microstructure 211 for the polarization component in the horizontal direction (x-axis direction) is denoted by neffh
  • neffv effective refractive index of the microstructure 211 for the polarization component in the vertical direction (y-axis direction
  • the refractive indexes neffh and neffv can be controlled by the combination of the width w1 and the width w2 , and take the values n0 ⁇ neffh ⁇ n1 and n0 ⁇ neffv ⁇ n1 , respectively.
  • the phase delay amounts ⁇ h and ⁇ v can be arbitrarily controlled by the combination of the width w 1 and the width w 2. That is, in the examples shown in Figures 5 to 7, by designing the width w 1 and the width w 2 of the microstructure 211, it is possible to arbitrarily set the phase delay amounts ⁇ h and ⁇ v for each polarization direction.
  • the axis of linear symmetry of the upper surface of the microstructure 211 is an axis parallel to the x-axis or an axis parallel to the y-axis.
  • the imaging element 3 can impart an arbitrary phase delay spatial distribution to each polarization direction by using the polarization wavelength separation lens 21 in which a plurality of microstructures 211 having appropriate widths w1 and w2 and axis of symmetry depending on the position on the x-axis and y-axis plane are arranged.
  • a plurality of microstructures 211 having appropriate widths w1 and w2 and axis of symmetry depending on the position on the x-axis and y-axis plane are arranged.
  • arbitrary wavefront control can be performed for each polarization direction.
  • phase delay amounts ⁇ h and ⁇ v are also functions of the wavelength ⁇ of the light, by combining the phase modulation function according to the polarization direction and the phase modulation function according to the wavelength, it is possible to realize a polarized wavelength separation lens 21 that has different focusing positions depending on the polarization direction and wavelength region of the light.
  • Figure 8 is a diagram showing an example of a side view of the microstructure 211 that constitutes the polarized wavelength separation lens 21 according to embodiment 1.
  • Figure 9 is a view taken along arrow C in Figure 8.
  • the microstructure 211 is formed on the bottom surface of the transparent substrate 10.
  • the upper surface which is the incident surface, is formed in a rectangular shape, and the axis of linear symmetry of the upper surface of the microstructure 211 is, for example, an axis parallel to the x-axis or y-axis.
  • FIG. 10 is a diagram showing another example of a side view of the microstructure 211 constituting the polarized wavelength separation lens 21 according to embodiment 1.
  • FIG. 11 is a view taken along arrow C in FIG. 10.
  • the microstructure 211 is formed on the bottom surface of the transparent substrate 10.
  • the shape of the upper surface, which is the incident surface is formed in a cross shape, and the axis of linear symmetry of the upper surface of the microstructure 211 is, for example, an axis parallel to the x-axis or an axis parallel to the y-axis.
  • Fig. 12 is a diagram showing calculation results of the phase delay characteristics of the microstructure 211 shown in Fig. 8 and Fig. 9.
  • Fig. 13 is a diagram showing calculation results of the phase delay characteristics of the microstructure 211 shown in Fig. 10 and Fig. 11.
  • a heat map in which the value of the phase delay amount for each combination of the width w1 in the x-axis direction and the width w2 in the y-axis direction of the microstructure 211 shown in Fig. 8 and Fig. 9 is expressed by a shade of gray is shown as a calculation result of the phase delay characteristic.
  • a heat map in which the value of the phase delay amount for each combination of the width w1 in the x-axis direction and the width w2 in the y-axis direction of the microstructure 211 shown in Fig. 10 and Fig. 11 is expressed by a shade of gray is shown as a calculation result of the phase delay characteristic.
  • phase delay amount ⁇ h and the phase delay amount ⁇ v can be realized by combining the widths w 1 and w 2 and the top surface shape of the microstructure 211. Furthermore, as shown in Fig. 12 and 13, it can be seen that in the microstructure 211, the phase delay amount ⁇ h and the phase delay amount ⁇ v have large wavelength dependency.
  • Figure 14 shows the calculation results of the phase delay characteristics of the microstructure 211 in which the axis of symmetry of the microstructure 211 shown in Figures 8 and 9 has been rotated by 45°.
  • Figure 15 shows the calculation results of the phase delay characteristics of the microstructure 211 in which the axis of symmetry of the microstructure 211 shown in Figures 10 and 11 has been rotated by 45°.
  • phase delay amount ⁇ h and the phase delay amount ⁇ v can be realized by combining the widths w 1 and w 2 and the top surface shape of the microstructure 211. Furthermore, as shown in Fig. 14 and 15, it can be seen that in the microstructure 211, the phase delay amount ⁇ h and the phase delay amount ⁇ v have large wavelength dependency.
  • FIG. 16 is a plan view schematically showing another example of a polarized wavelength separation lens 21 according to embodiment 1
  • FIG. 17 is a diagram schematically showing a portion of a cross section taken along line XVII-XVII shown in FIG. 16.
  • FIGS. 18 to 20 are diagrams showing examples of the phase delay spatial distribution achieved by the polarization wavelength separation lens 21 according to embodiment 1.
  • FIG. 18 shows an example of the phase delay spatial distribution when 450 nm light is incident
  • FIG. 19 shows an example of the phase delay spatial distribution when 540 nm light is incident
  • FIG. 20 shows an example of the phase delay spatial distribution when 640 nm light is incident.
  • a polarized wavelength separation lens 21 can be realized by forming different spatial phase delay distributions depending on the wavelength component and polarization direction. Note that similar designs can also be applied to other numbers of wavelength divisions and other numbers of polarization directions.
  • Parameters used in the design include, for example, pixel size, focal length, polarization direction to be separated, and center wavelength of each wavelength region to be separated.
  • the pixel size is 1.05 ⁇ m x 1.05 ⁇ m
  • the focal length is 5.5 ⁇ m
  • the center wavelengths of each wavelength region to be separated are, for example, 450 nm, 540 nm, and 640 nm, but are not limited to these examples.
  • the focal length is, for example, the distance in the z-axis direction between the polarization wavelength separation lens 21 and the pixel 41.
  • phase distribution of the polarization wavelength separation lens 21 can be expressed by the following equation (2):
  • x is the position in the x-axis direction
  • y is the position in the y-axis direction
  • xf is the focal position in the x-axis direction
  • yf is the focal position in the y-axis direction
  • zf is the focal position in the z-axis direction.
  • ⁇ (x, y) is the phase delay amount at positions x and y
  • ⁇ d is the center wavelength of the wavelength range to be separated
  • n0 is the refractive index of the transparent layer 30 on the transmission side
  • C is a constant.
  • the focusing positions xf , yf , and zf are set at the centers of 16 pixels 41 (e.g., see FIG. 16 ) corresponding to the combinations of polarization direction and wavelength component.
  • the phase distribution boundary regions of the polarized wavelength separation lens 21 are set so that they are symmetrical in both the x-axis and y-axis directions with respect to the phase distributions of adjacent polarized wavelength separation lenses 21 in both the x-axis and y-axis directions, centered on the focusing position.
  • the constant C may be optimized so that the phase distribution error is minimized for each combination of polarization direction and wavelength component.
  • the phase delay amount ⁇ calculated using equation (2) above is converted to fall within the range of 0 to 2 ⁇ . For example, -0.5 ⁇ is converted to 1.5 ⁇ , and 2.5 ⁇ is converted to 0.5 ⁇ .
  • the structure that best matches the phase distribution is, for example, a structure that minimizes the phase error, but is not limited to this example.
  • FIG. 21 is an enlarged view of region 21a in FIG. 16 in the polarized wavelength separation lens 21 according to embodiment 1.
  • Polarized light is expressed in two orthogonal polarization directions, so as shown in FIG. 21, in the polarized wavelength separation lens 21, microstructures 211a and 211b are arranged so as to be switched depending on the position.
  • microstructures 211a and microstructures 211b are arranged alternately in the x-axis direction (left-right direction) and y-axis direction (up-down direction), which are the periodic arrangement directions.
  • the microstructures 211a and 211b have axes of linear symmetry that differ by 45° from each other, and in region 21a, microstructures 211a and microstructures 211b whose axes of linear symmetry differ by 45° are arranged alternately.
  • the polarized wavelength separation lens 21 allows the polarized wavelength separation lens 21 to change the polarization direction in small incident area units, and to more appropriately focus incident light onto pixels 41 at different positions on the pixel array 40 depending on the polarization direction and wavelength components of the incident light.
  • the area in which microstructures 211a and microstructures 211b, whose axes of linear symmetry differ by 45°, are alternately arranged is the entire polarized wavelength separation lens 21, but it may also be a partial area of the polarized wavelength separation lens 21.
  • Fig. 22 is a diagram showing an example of a wavelength spectrum indicating the relationship between wavelength and received light intensity of each pixel 41 when linearly polarized light in the 0° direction is incident on the image sensor 3 according to embodiment 1.
  • (a) of Fig. 22 shows the relationship between wavelength and received light intensity of four pixels 41 whose combinations of polarization direction and wavelength component correspond to Rh , Rv , R45h , and R45v , and the peaks of the spectrum are present in the R (Red) wavelength region corresponding to these pixels 41.
  • 22(b) shows the relationship between the received light intensity and wavelength in each pixel 41 with combinations of polarization direction and wavelength component G rh , G rv , G r45h , and G r45v , with the spectral peaks existing in the wavelength region of G r (Green-Red) corresponding to these pixels 41.
  • 22(c) shows the relationship between the received light intensity and wavelength in each pixel 41 with combinations of polarization direction and wavelength component G bh , G bv , G b45h , and G b45v , with the spectral peaks existing in the wavelength region of G b (Green-Blue) corresponding to these pixels 41.
  • FIG. 22 shows the relationship between the received light intensity and wavelength at each pixel 41 for combinations of polarization direction and wavelength component Bh , Bv , B45h , and B45v , and the spectral peaks are present in the B (Blue) wavelength region to which these pixels 41 correspond.
  • the polarization wavelength separation lens 21 in the image sensor 3 has a wavelength separation function.
  • the 0° pixel 41 corresponding to the incident polarized light has the highest light intensity
  • the 90° pixel 41 that is orthogonal to the incident polarized light has the lowest light intensity.
  • the 0° pixels 41 are the pixels 41 for Rh , Grh , Gbh , and Bh
  • the 90° pixels 41 are the pixels 41 for Rv , Grv , Gbv , and Bv .
  • the average transmittance of the polarized wavelength separation lens 21 across the visible light band (400-700 nm) is approximately 77%, which is higher than the estimated transmittance of 15-20% for a two-layer filter array consisting of a color filter and a polarized filter. This also confirms that the polarized wavelength separation lens 21 increases the amount of light received by the pixel 41.
  • Figures 23 and 24 are diagrams showing examples of light intensity distributions on the pixel array 40 when light with different polarization states and wavelength combinations is incident perpendicularly on the image sensor 3 according to embodiment 1.
  • the polarization wavelength separation lens 21 can focus light onto pixels 41 that correspond to the combination of polarization direction and wavelength components.
  • the imaging device 1 equipped with the imaging element 3 according to the embodiment has a signal processing unit 4, which performs processing to improve image quality.
  • 16 pixels 41 form one unit structure, which may result in a degradation of spatial resolution compared to pixel-based monochrome image sensors and 4-pixel-based color image sensors.
  • the signal processing unit 4 performs demosaic processing, which can suppress degradation of spatial resolution.
  • crosstalk of polarization components and crosstalk of wavelength components may exist between pixels 41.
  • Crosstalk of polarization components between pixels 41 may lower the low polarization extinction ratio, and crosstalk of wavelength components between pixels 41 may cause color mixing. Therefore, the signal processing unit 4 corrects the value of the electrical signal output from the pixel array 40 based on the polarization characteristics and light reception spectrum characteristics of each pixel 41, thereby suppressing color mixing and a decrease in the polarization extinction ratio.
  • the signal processing unit 4 can create a color correction matrix based on the light reception spectral characteristics of each pixel 41, and perform matrix operations on the pixel values of the image after demosaicing (e.g., three channels in the case of three colors), thereby performing more appropriate color correction processing.
  • the signal processing unit 4 creates a polarization correction matrix based on the polarization characteristics of each pixel 41, and performs matrix operations on the pixel values of the image after demosaicing (for example, four channels in the case of four polarization directions), thereby enabling more appropriate polarization correction processing.
  • the shape of the upper surface (incident surface) of the microstructure 211 is rectangular or cross-shaped, but the shape of the upper surface of the microstructure 211 is not limited to rectangular or cross-shaped.
  • Figure 25 is a diagram showing other examples of the shape of the upper surface of the microstructure 211 in the polarization wavelength separation lens 21 according to embodiment 1.
  • the top surface shape of the microstructure 211 can be formed into various shapes, such as a shape with an opening, a shape consisting of multiple top surfaces arranged at intervals, or a shape with an elliptical outer edge.
  • the rectangular microstructure 211 described above, the cross-shaped microstructure 211, and the microstructures 211 shown in Figures 25(a) to 25(x) have top surface shapes with two-fold rotational symmetry axes having axis of linear symmetry, but are not limited to such examples.
  • the columnar shape is not limited to a columnar shape with a uniform cross-sectional shape in a direction perpendicular to the z-axis direction, but may have a structure in which part or all of the cross-sectional shape is different.
  • the image sensor 3 according to the first embodiment is not limited to the configuration shown in Fig. 17.
  • Figs. 26 to 28 are diagrams schematically showing a portion of a cross section of other configuration examples of the image sensor 3 according to the first embodiment.
  • the polarization wavelength separation lens 21 may be formed on top of the transparent layer 30 above the pixel array 40 or inside the transparent layer made of SiO2 .
  • the imaging element 3 shown in (a) of Figure 26 has a transparent layer 30 made of a material such as SiO2 , a microstructure 211 disposed above the transparent layer 30, and does not have a transparent substrate 10.
  • the imaging element 3 shown in (b) of Figure 26 has transparent layers including the transparent layer 30 made of a material such as SiO2 , and a microstructure 211 disposed inside the transparent layer made of the same material, including the transparent layer 30 and the transparent substrate 10.
  • the imaging element 3 shown in (c) of Figure 26 has a transparent layer 30 formed of a layer made of a material such as SiO2 and an air layer, and a microstructure 211 disposed above the transparent layer 30, and does not have a transparent substrate 10.
  • the microstructures 211 are configured with one layer in the above-described example, they may be configured with two or more layers.
  • each microstructure 211 is formed across two layers.
  • the transparent layer 30 is a layer made of a material such as SiO2
  • a first layer of multiple microstructures 211 is disposed on the upper surface of the transparent layer made of a material such as SiO2
  • the second layer of multiple microstructures 211 is covered with a transparent layer made of a material such as SiO2 .
  • the transparent layer 30 is a layer made of a material such as SiO2 , and a plurality of microstructures 211 are disposed inside the transparent layer made of the same material including the transparent layer 30 and the transparent substrate 10.
  • a plurality of microstructures 211 are formed on the top and bottom surfaces of the transparent layer made of a material such as SiO2 .
  • the image sensor 3 shown in Fig. 27(d) differs from the image sensor 3 shown in Fig. 27(a) in that the transparent layer 30 is formed of a layer made of SiO2 or the like and an air layer.
  • the image sensor 3 shown in Fig. 27(e) differs from the image sensor 3 shown in Fig. 27(b) in that the transparent layer 30 is formed of a layer made of SiO2 or the like and an air layer.
  • each microstructure 211 is formed across three layers.
  • the transparent layer 30 is a layer made of a material such as SiO2
  • the first layer of the multiple microstructures 211 is disposed on the upper surface of the transparent layer made of a material such as SiO2 , with the second and third layers of the multiple microstructures 211 being covered by this transparent layer.
  • the transparent layer 30 is a layer made of a material such as SiO2 , and a plurality of microstructures 211 are arranged inside the transparent layer made of the same material, including the transparent layer 30 and the transparent substrate 10.
  • the first and third layers of the plurality of microstructures 211 are formed on the top and bottom surfaces of the transparent layer made of a material such as SiO2 , and the second layer of the microstructures 211 is arranged on that transparent layer.
  • the imaging element 3 shown in Fig. 28(d) differs from the imaging element 3 shown in Fig. 28(a) in that the transparent layer 30 is formed of a layer made of a material such as SiO2 and an air layer.
  • the imaging element 3 shown in Fig. 28(e) has first and second layers of a plurality of microstructures 211 arranged inside a transparent layer made of a material such as SiO2 , and a third layer of a plurality of microstructures 211 arranged on the bottom surface of the transparent layer.
  • the image sensor 3 may have a front-illuminated structure that receives light from the side of the wiring layer 42. Furthermore, although not shown in figures such as FIGS. 26 to 28, the image sensor 3 may have a high-refractive index uneven structure made of SiN, TiO2, or the like between the pixel array 40 and the polarization wavelength separation lens 21, which operates as an internal microlens and serves to guide light that has passed through the polarization wavelength separation lens 21 to the photoelectric conversion element in the pixel 41.
  • the structures shown in FIGS. 26 to 28 are fabricated using known semiconductor manufacturing techniques.
  • Figure 29 is a side view showing a schematic example of a microstructure 211 according to embodiment 1.
  • the microstructure 211 shown in Figure 29(a) has a side surface similar to that of the microstructure 211 shown in Figure 6.
  • the microstructure 211 shown in Figure 29(b) is formed across two layers and has microstructure pieces 2111 and 2112 that have the same center line and shape.
  • the microstructure 211 shown in Figure 29(c) is formed across two layers and has microstructure pieces 2111, 2112 that have the same center line but different shapes.
  • the microstructure 211 shown in Figure 29(d) is formed across two layers and has microstructure pieces 2111, 2112 that have different center lines and different shapes. Note that the side shape of the microstructure 211 is not limited to the example shown in Figure 29.
  • pixels 41 of the same wavelength component are arranged adjacently in the x-axis direction and the y-axis direction, so that the four pixels 41 of the same wavelength component are grouped together.
  • a pixel array 40 arranged in this manner can reduce crosstalk between wavelength components, but the arrangement of pixels 41 corresponding to combinations of polarization direction and wavelength component is not limited to the example described above.
  • FIGS. 30 and 31 are diagrams schematically illustrating other examples of the arrangement of pixels 41 in a pixel array 40 of an image sensor 3 according to an embodiment.
  • the pixel array 40 shown in FIGS. 30 and 31 four pixels 41 with the same polarization direction are arranged together by being adjacent to each other in the x-axis direction and the y-axis direction. In this way, in the pixel array 40 shown in FIGS. 30 and 31, four pixels 41 with the same polarization direction are arranged together, thereby making it possible to reduce crosstalk in the polarization direction between the pixels 41.
  • the image sensor 3 is not limited to a normal incidence compatible image sensor.
  • a normal incidence compatible image sensor if incident light is incident at an angle to the incident surface of the image sensor 3, the main light incident angle may differ between the center and edges of the pixel array 40.
  • a normal incidence compatible imaging element if incident light is incident at an angle relative to the incidence surface of the imaging element 3, the light may not be incident on the appropriate pixel 41, which could cause image degradation. Therefore, in embodiment 1, when incident light is incident in a direction perpendicular to the incidence surface of the imaging element 3, an oblique incidence compatible imaging element that is compatible with oblique incidence depending on the position of the pixel array 40 is used as the imaging element 3.
  • FIG. 32 is a plan view schematically showing another example of the image sensor 3 according to embodiment 1
  • FIG. 33 is a diagram schematically showing a portion of a cross section taken along line XXXIII-XXXIII shown in FIG. 32.
  • FIG. 34 is a diagram for explaining the angle of incidence ⁇ of light incident on the image sensor 3 shown in FIGS. 32 and 33.
  • FIG. 35 is a plan view schematically showing another example of the image sensor 3 according to embodiment 1
  • FIG. 36 is a diagram schematically showing a portion of a cross section taken along line XXXVI-XXXVI shown in FIG. 35.
  • the image sensor 3 shown in Figures 32 and 33 is an image sensor compatible with oblique incidence, in which the polarized wavelength separation lens 21 is positioned at a position shifted in the x-axis and y-axis directions relative to the unit structure (16 pixels 41) of the pixel array 40.
  • the focusing position of the polarized wavelength separation lens 21 shifts for incident light with an incident angle ⁇ (see Figure 34) that has an inclination angle in the x-axis and y-axis directions, so by shifting the position of the polarized wavelength separation lens 21 in the x-axis and y-axis directions to cancel out this shift, it is possible to accommodate oblique incidence.
  • the image sensor 3 shown in Figures 35 and 36 is an image sensor compatible with oblique incidence, and similar to the image sensor 3 shown in Figure 3, the polarization wavelength separation lens 21 and the unit structure (16 pixels 41) of the pixel array 40 are positioned opposite each other.
  • the polarized wavelength separation lens array 20 is designed so that incident light incident at an incident angle ⁇ (see Figure 34) is perpendicularly incident on the pixel 41 directly below, and the polarized wavelength separation lens array 20 is positioned according to the position of the pixel array 40.
  • the following equation (3) is the equation for the phase distribution of the lens that guides light with an incident angle ⁇ to the center of the pixel 41 directly below, and the polarized wavelength separation lens array 20 of the image sensor 3 shown in Figures 35 and 36 can be designed by performing a design similar to that when using equation (2) above.
  • x is the position in the x-axis direction
  • y is the position in the y-axis direction
  • xf is the focal position in the x-axis direction
  • yf is the focal position in the y-axis direction
  • zf is the focal position in the z-axis direction.
  • ⁇ (x, y) is the phase delay amount at positions x and y
  • ⁇ d is the center wavelength of the wavelength range to be separated
  • n in is the refractive index of the material on the incident side
  • n out is the refractive index of the material on the exit side
  • C is a constant.
  • Fig. 37 is a diagram schematically showing a part of a cross section of an image sensor according to Embodiment 2.
  • an image sensor 3A according to Embodiment 2 differs from the image sensor 3 according to Embodiment 1 in that it has a color filter 50 above the pixel array 40.
  • the color filter 50 is disposed between the polarized wavelength separation lens array 20 and the pixel array 40, more specifically, between the pixel array 40 and the transparent layer 30.
  • the color filter 50 is a filter that transmits wavelength components (e.g., color regions) corresponding to the pixel 41 and cuts out light of other wavelength components (e.g., color regions), and is provided, for example, for each pixel 41 or for multiple pixels 41.
  • the color filter 50 is made of resin or the like, and is realized using known technology.
  • Light incident on the image sensor 3A is wavelength-separated by the polarized wavelength separation lens 21, and then incident on the color filter 50 directly above the pixel array 40 and filtered.
  • the transmitted wavelength components of the color filter 50 match the wavelength components corresponding to the pixels 41 directly below, and the color filter 50 transmits light of the wavelength components corresponding to the pixels 41 directly below.
  • the image sensor 3A can guide light to the photoelectric conversion elements of the pixels 41 while cutting out components other than the desired wavelength component.
  • the image sensor 3A can achieve the same functionality as the image sensor 3 of embodiment 1, while significantly reducing crosstalk of wavelength components between the pixels 41.
  • the image sensor 3A which uses both the polarizing wavelength separation lens 21 and the color filter 50, can maintain high light utilization efficiency. This is because filtering by the color filter 50 occurs after color separation (wavelength separation) by the polarizing wavelength separation lens 21, so there is almost no reduction in the total amount of light reaching the pixel array 40.
  • Fig. 38 is a diagram schematically showing a part of a cross section of an image sensor according to embodiment 3.
  • an image sensor 3B according to embodiment 3 differs from the image sensor 3 according to embodiment 1 in that it has a polarizing filter 60 above the pixel array 40.
  • the polarizing filter 60 is disposed between the polarized wavelength separation lens array 20 and the pixel array 40, more specifically, between the pixel array 40 and the transparent layer 30.
  • the polarizing filter 60 is a filter that transmits light of the polarization direction corresponding to the pixel 41 and cuts light of other polarization directions, and is provided, for example, for each pixel 41 or for multiple pixels 41.
  • the polarizing filter 60 is composed of a metal wire grid or a photonic crystal, and is realized using known technology.
  • Light incident on the image sensor 3B is wavelength-separated by the polarizing wavelength separation lens 21, and then enters the polarizing filter 60 directly above the pixel array 40 and is filtered.
  • the transmission polarization axis of the polarizing filter 60 coincides with the polarization direction corresponding to the pixel 41 directly below, and the polarizing filter 60 transmits light with the polarization direction corresponding to the pixel 41 directly below.
  • the image sensor 3B can guide light to the photoelectric conversion elements of the pixels 41 while cutting out components other than the desired polarization component.
  • the image sensor 3B can achieve the same functionality as the image sensor 3 of embodiment 1, while also significantly eliminating crosstalk in the polarization direction between the pixels 41 and improving the polarization extinction ratio.
  • the image sensor 3B which uses both the polarized wavelength separation lens 21 and the polarizing filter 60, can maintain high light utilization efficiency. This is because the polarized light separation by the polarized wavelength separation lens 21 is followed by filtering by the polarizing filter 60, so there is almost no reduction in the total amount of light reaching the pixel array 40.
  • Fig. 39 is a diagram schematically illustrating a portion of a cross section of an image sensor according to the fourth embodiment.
  • the image sensor 3C according to the fourth embodiment differs from the image sensor 3 according to the first embodiment in that it has a color filter 50 and a polarizing filter 60 above the pixel array 40.
  • the color filter 50 is disposed between the polarized wavelength separation lens array 20 and the pixel array 40, more specifically, between the pixel array 40 and the transparent layer 30.
  • the color filter 50 is a filter that transmits wavelength components (e.g., color regions) corresponding to the pixel 41 and cuts out light of other wavelength components (e.g., color regions), and is provided, for example, for each pixel 41 or for multiple pixels 41.
  • the color filter 50 is made of resin or the like, and is realized using known technology.
  • the polarizing filter 60 is disposed between the polarized wavelength separation lens array 20 and the pixel array 40, more specifically, between the pixel array 40 and the transparent layer 30, directly above the color filter 50.
  • the polarizing filter 60 is a filter that transmits light of the polarization direction corresponding to the pixel 41 and cuts light of other polarization directions, and is provided, for example, for each pixel 41 or for multiple pixels 41.
  • the polarizing filter 60 is formed from a metal wire grid or a photonic crystal, and is realized using known technology. The arrangement of the polarizing filter 60 is not limited to the example shown in Figure 39, and the polarizing filter 60 may be disposed between the color filter 50 and the pixel array 40.
  • Light incident on the image sensor 3C is wavelength-separated by the polarizing wavelength separation lens 21, and then enters the polarizing filter 60 directly above the pixel array 40, where it is polarized and separated.
  • the transmission polarization axis of the polarizing filter 60 coincides with the polarization direction corresponding to the lower pixel 41, and the polarizing filter 60 transmits light with the polarization direction corresponding to the lower pixel 41.
  • Light that passes through the polarizing filter 60 is incident on the color filter 50 directly above the pixel array 40 and filtered.
  • the wavelength components transmitted by the color filter 50 match the wavelength components corresponding to the pixel 41 directly below, and the color filter 50 transmits light of the wavelength components corresponding to the pixel 41 directly below.
  • the image sensor 3C is provided with a polarizing filter 60 and a color filter 50, which allows it to guide light to the photoelectric conversion elements of the pixels 41 while cutting out components other than the desired color component and the desired polarization component. Therefore, the image sensor 3C achieves the same functionality as the image sensor 3 of embodiment 1, while significantly reducing polarization direction crosstalk between pixels 41 and wavelength component crosstalk between pixels 41.
  • the image sensor 3C which combines the polarizing wavelength separation lens 21, color filter 50, and polarizing filter 60, can maintain high light utilization efficiency. This is because filtering by the polarizing filter 60 and color filter 50 is performed after polarization separation and wavelength separation (e.g., color separation) by the polarizing wavelength separation lens 21, so there is almost no reduction in the total amount of light reaching the pixel array 40.
  • the pixel size, focal length, number and type of polarization directions to be separated, number and type of wavelength components to be separated, etc. are not limited to the examples described above, and can be changed depending on the lens design, required spatial resolution, etc.
  • the present invention is not limited to such examples.
  • materials such as SiN, SiC, TiO 2 , and GaN are suitable materials for the polarization wavelength separation lens 21 because they have a high refractive index and low absorption loss.
  • the image pickup elements 3, 3A, 3B, and 3C are used in the near-infrared region with wavelengths ranging from 800 to 1000 nm
  • materials such as Si, SiC, SiN, TiO 2 , GaAs, and GaN are suitable materials for the polarization wavelength separation lens 21 that have low loss for this light.
  • the imaging elements 3, 3A, 3B, and 3C are used in the long wavelength near-infrared region (such as the communication wavelengths of 1.3 ⁇ m or 1.55 ⁇ m)
  • InP or the like can be used as the material for the polarization wavelength separation lens 21.
  • examples of materials include polyimides such as fluorinated polyimide, BCB (benzocyclobutene), photocurable resins, UV epoxy resins, acrylic resins such as PMMA, and polymers such as general resists.
  • polyimides such as fluorinated polyimide, BCB (benzocyclobutene), photocurable resins, UV epoxy resins, acrylic resins such as PMMA, and polymers such as general resists.
  • the material of the transparent layer 30 may be a general glass material, SiO 2 , an air layer, or the like, as long as it has a refractive index lower than the refractive index of the material of the polarized wavelength separation lens 21 and has low loss for the wavelength of the incident light.
  • the transparent layer 30 may be a transparent layer having a layered structure made of multiple materials.
  • the polarization components separated by the polarization wavelength separation lens 21 are linearly polarized light oriented at 0°, 45°, 90°, and -45° relative to any one axis.
  • this is not limited to this.
  • it may also be possible to separate circularly polarized or elliptically polarized components, and a configuration that combines the separation of linearly polarized and circularly polarized components is also possible.
  • an imaging element can be considered that is composed of three polarization units (two for separating linearly polarized components and one for separating circularly polarized components) each with the function of separating linearly polarized light oriented at 0°, 45°, 90°, and -45°, and the function of separating right-handed and left-handed circularly polarized components.
  • the light in the three wavelength regions supported by the polarized wavelength separation lens 21 is light of the three primary colors R, G, and B, or one of the four wavelength regions supported by the polarized wavelength separation lens 21 is infrared light, which is light of a wavelength other than the three primary colors, but this is not limited to such examples.
  • the wavelengths that can be separated by the polarized wavelength separation lens 21 may be light of a wavelength other than the three primary colors in at least one of the three wavelength regions (e.g., infrared light or ultraviolet light), or light of a wavelength other than the three primary colors in at least two of the four wavelength regions (e.g., infrared light or ultraviolet light).
  • the imaging elements 3, 3A, 3B, and 3C have a pixel array 40 in which a plurality of pixels 41, each including a photoelectric conversion element, are arranged in a two-dimensional array, and a polarization wavelength separation lens array 20 in which a plurality of polarization wavelength separation lenses 21, each having a periodic arrangement of microstructures 211 that focus incident light to different positions on the pixel array 40 depending on the polarization direction and wavelength component of the incident light, are arranged in a two-dimensional array.
  • the polarization wavelength separation lens array 20 is an example of a spectroscopic element array
  • the polarization wavelength separation lens 21 is an example of a spectroscopic element.
  • the arrangement period P of the plurality of microstructures 211 is shorter than the wavelength of light to be received by the pixel array 40.
  • All or some of the plurality of microstructures 211 have a surface, on which incident light is incident, that has an axis of linear symmetry and a shape whose length differs in the direction of the axis of linear symmetry and the direction perpendicular to the axis of linear symmetry, and the axis of linear symmetry and the structure are modulated depending on the position on the polarization wavelength separation lens 21.
  • the image sensor 3 can separate the polarization direction and wavelength of incident light without using a color filter or polarizing filter, which reduces the number of parts required and contributes to lower costs.
  • the image sensor 3, 3A, 3B, and 3C can increase imaging sensitivity by using the polarization wavelength separation lens array 20, thereby reducing the cost of the image sensor with increased imaging sensitivity.
  • the axis of linear symmetry of all or some of the multiple microstructures 211 differs by 45° from the axis of linear symmetry of adjacent microstructures 211 in the arrangement direction of the periodic array. This allows the image sensors 3, 3A, 3B, and 3C to vary the polarization direction in small incident area units, and more appropriately focus incident light on pixels 41 at different positions on the pixel array 40 depending on the polarization direction and wavelength components of the incident light.
  • the multiple microstructures 211 have the same length in a direction perpendicular to the pixel array surface of the pixel array 40. This makes it easy to create multiple microstructures 211.
  • the multiple microstructures 211 are configured across multiple layers. This allows for greater freedom in designing the microstructures 211 in the imaging elements 3, 3A, 3B, and 3C.
  • Imaging device 1
  • Lens optical system 3 3A, 3B, 3C Imaging element 4
  • Signal processing unit 10 Transparent substrate 20
  • Polarized wavelength separation lens array 21
  • Polarized wavelength separation lens 30
  • Transparent layer 40
  • Pixel array 41
  • Pixel 42 Wiring layer 50
  • Color filter 60

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Multimedia (AREA)
  • Signal Processing (AREA)
  • Polarising Elements (AREA)

Abstract

L'invention concerne un élément d'imagerie (3) comprenant un réseau de pixels (40) dans lequel une pluralité de pixels (41) comprenant un élément de conversion photoélectrique sont agencés dans un réseau bidimensionnel et un réseau d'éléments spectroscopiques dans lequel des éléments spectroscopiques ayant des agencements périodiques d'une pluralité de structures fines permettant de focaliser la lumière incidente sur différentes positions sur le réseau de pixels (40) selon la direction de polarisation et la composante de longueur d'onde de la lumière incidente sont agencés dans un réseau bidimensionnel. La période d'agencement de la pluralité de structures fines est plus courte que la longueur d'onde de la lumière à recevoir par le réseau de pixels (40) et la totalité ou une partie de la pluralité de structures fines a un axe de symétrie de ligne et a une surface qui est formée de manière à différer en longueur entre la direction de l'axe de symétrie de ligne et la direction orthogonale à l'axe de symétrie de ligne en tant que surface sur laquelle la lumière incidente est incidente. L'axe de symétrie de ligne et la structure sont modulés en fonction de la position dans l'élément spectroscopique.
PCT/JP2024/021424 2024-06-12 2024-06-12 Élément d'imagerie et dispositif d'imagerie Pending WO2025258002A1 (fr)

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Publication number Priority date Publication date Assignee Title
JP2012015424A (ja) * 2010-07-02 2012-01-19 Panasonic Corp 固体撮像装置
JP2015028960A (ja) * 2011-12-01 2015-02-12 ソニー株式会社 固体撮像装置および電子機器
WO2017187804A1 (fr) * 2016-04-28 2017-11-02 シャープ株式会社 Appareil de capture d'images
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WO2020066738A1 (fr) * 2018-09-26 2020-04-02 日本電信電話株式会社 Système d'imagerie de polarisation
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WO2021234924A1 (fr) * 2020-05-21 2021-11-25 日本電信電話株式会社 Élément de capture d'image et dispositif de capture d'image
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