Imaging element and imaging device

Abstract

Provided is an imaging element that does not require switching between wavelength bands.　The present technology provides an imaging element comprising: a phase difference adjustment unit in which a phase difference given to polarized incident light varies in accordance with the wavelength band of the incident light; and a polarization sensor that acquires optical information from the phase difference adjustment unit. The polarization sensor may have a plurality of regions having different sensitivities depending on the direction of polarization. The phase difference adjustment unit may be configured to be separable from the polarization sensor.

Description

Image sensor and image pickup device

[0001] The technology according to the present disclosure (hereinafter also referred to as "the technology") relates to an imaging element and an imaging device.

[0002] Technologies are being used to measure the characteristics of objects using light in a specific wavelength band. For example, chlorophyll in plants absorbs visible light and strongly reflects near-infrared (NIR) light. Therefore, using light in the NIR wavelength band allows for the measurement of the chlorophyll content and water content of plants, improving the accuracy of measurements of the plant's growth status and type.

[0003] The wavelength band to be used varies depending on the object to be measured. For example, sunlight contains light of multiple wavelength bands, so it is necessary to use a filter or the like to extract light of a specific wavelength band.

[0004] Patent Documents 1 to 3 disclose techniques for switching wavelength bands using a plurality of filters, etc. Patent Document 4 discloses a technique related to a polarization sensor.

[0005] JP 2017-9394 A JP 2001-21488 A JP 2016-223971 A JP 2018-36314 A

[0006] In the techniques disclosed in Patent Documents 1 to 3, if the object to be measured moves when switching wavelength bands, noise may occur in the measurement results. For example, to measure the chlorophyll content or moisture content in order to understand the growth status of crops, light in the wavelength bands of 400 to 500 nm and 700 to 1200 nm may be measured. In this case, if the object moves due to wind or other factors when switching filters, light sources, etc., noise may occur in the measurement results.

[0007] The technology disclosed in Patent Document 4 is a technology related to a polarization sensor, but does not describe a technology for changing the wavelength band depending on the object to be measured.

[0008] Therefore, a main object of the present technology is to provide an imaging element and an imaging device that do not require switching of wavelength bands.

[0009] The present technology provides an imaging element including: a phase difference adjustment unit that applies a phase difference to polarized incident light that varies depending on the wavelength band of the incident light; and a polarization sensor that acquires optical information from the phase difference adjustment unit. The polarization sensor may have a plurality of regions whose sensitivity varies depending on the polarization direction. The phase difference adjustment unit may be configured to be separable from the polarization sensor. The phase difference adjustment unit may include a resin film. The phase difference adjustment unit may include a crystalline material or an optical multilayer film. The imaging element may further include a polarizing unit that polarizes the incident light. The polarizing unit may include a dye. The polarizing unit may include iodine. The polarizing unit may include an optical multilayer film. The imaging element may further include an optical system that causes the incident light to be incident approximately perpendicularly to the polarization sensor. The incident light that enters the phase difference adjustment unit may include near-infrared light or visible light. The imaging element may further include a wavelength selection unit that selects a wavelength band of the incident light that enters the phase difference adjustment unit. The imaging element may further include a depolarization unit that depolarizes the polarization included in the incident light that enters the polarization unit. The polarizing unit may further include a high-phase difference unit that imparts a phase difference to incident light that is incident on the polarizing unit. The present technology also provides an imaging device that includes: a phase difference adjustment unit that imparts a phase difference that varies with a wavelength band of the polarized incident light; a polarization sensor that acquires optical information from the phase difference adjustment unit; and a calculation unit that calculates the optical information.

[0010] According to the present technology, it is possible to provide an imaging element and an imaging device that do not require switching of wavelength bands. Note that the effects described herein are not necessarily limited to those described herein and may be any of the effects described in the present disclosure.

[0011] FIG. 1 is a schematic diagram showing an example configuration of an image sensor 10 according to an embodiment of the present technology. FIG. 2 is a schematic diagram showing an example configuration of an image sensor 10 according to an embodiment of the present technology. FIG. 3 is a graph showing an example of characteristics of a polarization sensor 2 according to an embodiment of the present technology. FIG. 4 is a graph showing an example of characteristics of a polarization unit 3 according to an embodiment of the present technology. FIG. 4 is a schematic diagram showing an example configuration of an image sensor 10 according to an embodiment of the present technology. FIG. 5 is a schematic diagram showing an example configuration of an image sensor 10 according to an embodiment of the present technology. FIG. 6 is a graph showing an example of characteristics of a polarization sensor 2 according to an embodiment of the present technology. FIG. 7 is a schematic diagram showing an example configuration of an image sensor 10 according to an embodiment of the present technology. FIG. 8 is a schematic diagram showing an example configuration of an image sensor 10 according to an embodiment of the present technology.

[0012] Hereinafter, preferred embodiments for implementing the present technology will be described with reference to the drawings. Note that the embodiment described below shows an example of a typical embodiment of the present technology, and does not limit the scope of the present technology. In addition, the present technology can be combined with any of the following examples and their modifications.

[0013] In the following description of the embodiments, configurations may be described using terms including "approximately," such as "approximately parallel" and "approximately perpendicular." For example, "approximately parallel" does not only mean completely parallel, but also means substantially parallel, i.e., including a state where the orientation is deviated from the completely parallel state by, for example, a few percent. The same applies to other terms including "approximately." Furthermore, each figure is a schematic diagram and is not necessarily an accurate depiction. The scale of the drawings has been exaggerated to make the features of the technology easier to understand. Therefore, it should be noted that the scale of the drawings and the scale of the actual device are not necessarily the same.

[0014] Unless otherwise specified, in the drawings, "top" means the top or upper side in the drawing, "bottom" means the bottom or lower side in the drawing, "left" means the left or left side in the drawing, and "right" means the right or right side in the drawing. Furthermore, in the drawings, the same or equivalent elements or members are given the same reference numerals, and redundant explanations will be omitted.

[0015] The description will be given in the following order: 1. First embodiment of the present technology (example 1 of image sensor) (1) Overview (2) Incident light (3) Phase difference adjustment unit 1 (4) Polarization sensor 2 2. Second embodiment of the present technology (example 2 of image sensor) 3. Third embodiment of the present technology (example 3 of image sensor) 4. Fourth embodiment of the present technology (example 4 of image sensor) 5. Fifth embodiment of the present technology (example 5 of image sensor) 6. Sixth embodiment of the present technology (example 6 of image sensor) 7. Seventh embodiment of the present technology (example of imaging device)

[0016] [1. First Embodiment of the Present Technology (First Example of Image Sensor)] [(1) Overview] The present technology provides an image sensor including: a phase difference adjustment unit that applies a phase difference to polarized incident light that varies depending on the wavelength band of the incident light; and a polarization sensor that acquires light information from the phase difference adjustment unit.

[0017] An imaging element according to an embodiment of the present technology will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing an example of the configuration of an imaging element 10 according to an embodiment of the present technology.

[0018] As shown in FIG. 1 , the image sensor 10 includes a phase difference adjustment unit 1 and a polarization sensor 2 .

[0019] The phase difference adjusting unit 1 receives incident light L polarized in a predetermined direction and having different wavelengths. N , L R , L G , L B The incident light L N , L R , L G , L B are preferably all polarized in the same direction.

[0020] The phase difference adjusting unit 1 adjusts the polarized incident light L N , L R, L G , L B In this example, the phase difference adjusting unit 1 applies a phase difference to the polarized incident light L N , L R , L G , L B By giving a phase difference to the incident light L, it becomes elliptically polarized. N , L R , L G , L B The direction of the ellipse varies depending on the wavelength band.

[0021] The polarization sensor 2 acquires optical information from the phase difference adjustment unit 1. As will be described in detail later, for example, if the polarization sensor 2 has multiple regions with different sensitivities depending on the polarization direction, the polarization sensor 2 can selectively receive light of wavelengths having polarization directions with high sensitivity. This eliminates the need to switch wavelength bands. Note that this effect also occurs in the other embodiments described later. Therefore, repeated explanation may be omitted in the explanation of other embodiments.

[0022] (2) Incident Light The incident light incident on the phase difference adjusting unit 1 preferably contains near-infrared light or visible light, which makes it possible to measure, for example, the growth status and type of a plant.

[0023] Near-infrared light has a longer wavelength than visible light, so it can avoid the absorption of chlorophyll and obtain information on moisture and protein. Water easily absorbs near-infrared light, so it can be used to measure the moisture content of plants. Protein also easily absorbs near-infrared light, so it can be used to measure the protein content of plants.

[0024] Visible light can be used to measure the chlorophyll content and leaf condition by utilizing the absorption of chlorophyll. Chlorophyll absorbs the blue and red colors of visible light and reflects the green. Therefore, the higher the chlorophyll content, the greener the leaf appears. The amount of visible light absorbed also changes depending on the condition of the leaf. For example, leaves infected with pests or diseases may turn yellow or brown due to a decrease in chlorophyll content.

[0025] (3) Phase Difference Adjustment Unit 1 A specific operation of the phase difference adjustment unit 1 will be described with further reference to Fig. 2. Fig. 2 is a schematic diagram showing an example of the configuration of an imaging element 10 according to an embodiment of the present technology.

[0026] 2, first polarized light L1 and second polarized light L2 polarized in the 0-degree direction from, for example, a light source (not shown) are incident on the phase difference adjustment unit 1. The wavelength of the first polarized light L1 is 400 nm, and the wavelength of the second polarized light L2 is 800 nm.

[0027] The phase difference adjusting unit 1 is designed, for example, to provide a phase difference of 400 nm between two orthogonal polarization components in the wavelength band of incident light in the range of 400 to 800 nm, and also, for example, to have a slow axis angle of 45 degrees.

[0028] The phase difference adjusting unit 1 imparts a phase difference to each of the first polarized light L1 and the second polarized light L2. When the first polarized light L1, which has a wavelength of 400 nm, passes through the phase difference adjusting unit 1, the phase goes around once and returns to the original state. In other words, the polarization direction of the first polarized light L1 remains at 0 degrees.

[0029] On the other hand, when the second polarized light L2 having a wavelength of 800 nm passes through the phase difference adjusting unit 1, the phase rotates half a circle, that is, the polarization direction of the second polarized light L2 becomes 90 degrees.

[0030] In this way, the phase difference that the phase difference adjusting section 1 gives to the incident light varies depending on the wavelength band of the incident light.

[0031] The means for forming the retardation adjustment unit 1 is not particularly limited, but for example, the retardation adjustment unit 1 may have a resin film. That is, the retardation adjustment unit 1 may be formed by applying a stretching process to a resin. The refractive index of the resin film differs between the stretching direction and the direction perpendicular to the stretching direction. By utilizing this property, the retardation adjustment unit 1 can impart a phase difference to the polarized component of incident light. The retardation adjustment unit 1 having a resin film has the advantages of being easy to manufacture and reducing manufacturing costs. Furthermore, by combining multiple resin films, it is possible to impart any phase difference over a wide wavelength band, making it applicable to a variety of applications.

[0032] Alternatively, the phase difference adjusting unit 1 may include a crystalline material. Crystalline materials have the property that their refractive index varies depending on the polarization state of light. By utilizing this property, the phase difference adjusting unit 1 can impart a phase difference to the polarization components of incident light. A phase difference adjusting unit 1 including a crystalline material has the advantage of being resistant to ultraviolet light, for example. When the incident light is ultraviolet light, for example, the phase difference adjusting unit 1 preferably includes a crystalline material.

[0033] Crystals have a structure in which atoms are regularly arranged. This structure suppresses the absorption of ultraviolet rays. Ultraviolet rays have a short wavelength and therefore tend to be easily absorbed by matter. Because crystals have a structure in which atoms are regularly arranged, the interaction between the wavelength of ultraviolet rays and the atoms within the crystal is weaker. This suppresses the absorption of ultraviolet rays, giving crystals their resistance to ultraviolet rays.

[0034] Resistance to ultraviolet light varies depending on the type of crystal. For example, diamond has a crystalline structure in which carbon atoms are regularly arranged, and it absorbs very little ultraviolet light, making it usable as a material that is resistant to ultraviolet light.

[0035] Alternatively, the retardation adjustment section 1 may have liquid crystal. That is, the retardation adjustment section 1 may be formed by applying liquid crystal molecules. Alternatively, the retardation adjustment section 1 may be a liquid crystal cell formed by sandwiching liquid crystal molecules between two glass substrates. Liquid crystal molecules can change their polarization state depending on voltage, temperature, and the like. By utilizing this property, the retardation adjustment section 1 can impart a phase difference to the polarized components of incident light. The retardation adjustment section 1 formed by applying liquid crystal molecules has advantages such as high transmittance and the ability to arbitrarily adjust the retardation. Furthermore, since it can be easily made smaller and lighter, it can be used in portable optical devices and the like.

[0036] Alternatively, the phase difference adjusting section 1 may have an optical multilayer film. For example, a columnar structure thin film formed by oblique deposition can be used as the phase difference adjusting section 1 having an optical multilayer film. Oblique deposition can create a difference in the density of the deposited material between the incident plane of deposition and the direction perpendicular to it, and can cause the formed thin film to exhibit optical anisotropy.

[0037] The image sensor 10 may include one phase difference adjustment unit 1, but preferably includes multiple phase difference adjustment units. By including multiple phase difference adjustment units in the image sensor 10, it becomes easier to create an arbitrary polarization state in a more specific wavelength band. By combining multiple phase difference adjustment units 1, it becomes easier to arbitrarily adjust the deviation in the delay amount for each wavelength. This deviation delays only light of a specific wavelength, making it possible to create an arbitrary polarization state.

[0038] For example, if only one phase difference adjustment unit 1 is provided, the amount of delay for light of a specific wavelength is determined by the material, making it difficult to provide an arbitrary phase difference for each wavelength. On the other hand, if two phase difference adjustment units 1 are provided, the light delayed by the first phase difference adjustment unit 1 can be further delayed by the second phase difference adjustment unit 1. This allows only light of a specific wavelength to be further delayed, making it easier to provide an arbitrary polarization state for each wavelength.

[0039] [(4) Polarization Sensor 2] The configuration of the polarization sensor 2 is not particularly limited, but in this configuration example, the polarization sensor 2 has multiple regions with different sensitivities depending on the polarization direction. For example, the polarization sensor 2 has a first region (pixel) 21, a second region (pixel) 22, a third region (pixel) 23, and a fourth region (pixel) 24.

[0040] For example, the first region 21 strongly detects light with a polarization direction of 0 degrees. The second region 22 strongly detects light with a polarization direction of 30 degrees. The third region 23 strongly detects light with a polarization direction of 90 degrees. The fourth region 24 strongly detects light with a polarization direction of 45 degrees. With this configuration, when the first polarized light L1, which has a wavelength of 400 nm and a polarization direction of 0 degrees, is incident on the polarization sensor 2, the sensitivity of the first region 21 is high. When the second polarized light L2, which has a wavelength of 800 nm and a polarization direction of 90 degrees, is incident on the polarization sensor 2, the sensitivity of the third region 23 is high.

[0041] This will be described with reference to Fig. 3 and Fig. 4. Fig. 3 and Fig. 4 are graphs showing an example of light received by the polarization sensor 2 according to an embodiment of the present technology. In Fig. 3 and Fig. 4, the horizontal axis represents wavelength, and the vertical axis represents intensity (sensitivity).

[0042] 3 shows the characteristics in the first region 21, which strongly detects light with a polarization direction of 0 degrees. Due to the action of the phase difference adjustment unit 1, the polarization direction of light near a wavelength of 400 nm is 0 degrees, and the polarization direction of light near a wavelength of 800 nm is 90 degrees. Therefore, as shown in FIG. 3, in the first region 21, the intensity is high when the wavelength of the incident light is 400 nm.

[0043] 4 shows the characteristics in the third region 23, which strongly detects light with a polarization direction of 90 degrees. As shown in FIG. 4, when the wavelength of the incident light is 800 nm, the intensity is high.

[0044] In this way, by combining the phase difference adjusting unit 1 and the polarization sensor 2, it is possible to selectively receive light of a wavelength having a polarization direction for which sensitivity is high, thereby eliminating the need to switch wavelength bands.

[0045] In this case, it is preferable that the phase difference adjustment unit 1 is configured to be separable from the polarization sensor 2. The wavelength band used varies depending on the object to be measured. For this reason, the phase difference adjustment unit 1 is configured to be separable, and a desired phase difference can be imparted to light in a desired wavelength band by replacing or rotating the phase difference adjustment unit 1. As a result, the range of objects that can be measured is expanded.

[0046] The above description of the imaging element according to the first embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0047] [2. Second Embodiment of the Present Technology (Example 2 of Image Sensor)] It is sufficient if the light source or the object to be measured emits or reflects polarized light to the phase difference adjustment unit 1, but if the light source or the object to be measured does not emit or reflect polarized light, it is preferable to further include a polarization unit that polarizes incident light. This will be described with reference to Fig. 5. Fig. 5 is a schematic diagram showing an example configuration of an image sensor 10 according to an embodiment of the present technology.

[0048] 5 , the image sensor 10 according to this embodiment further includes a polarization unit 3. The polarization unit 3 polarizes incident light from a light source or a measurement object (not shown), and emits the polarized light toward the phase difference adjustment unit 1.

[0049] An example of the characteristics of the polarizing unit 3 will be described with reference to Fig. 6 . Fig. 6 is a graph showing an example of the characteristics of the polarizing unit 3 according to an embodiment of the present technology. The horizontal axis of Fig. 6 represents the wavelength [nm] of light. The vertical axis represents the transmittance [%] of light. As shown in Fig. 6 , the transmittance varies depending on the wavelength.

[0050] The configuration of the polarizing unit 3 is not particularly limited, but the polarizing unit 3 may be, for example, a wire grid type. The wire grid type polarizing unit 3 is composed of a grid in which metal wires or conductive plastic wires are regularly arranged. Only light whose vibration direction is polarized in a direction perpendicular to the grid passes through, while light polarized in other directions is reflected and absorbed.

[0051] Alternatively, the polarizing unit 3 may be crystalline. The crystalline polarizing unit 3 is formed by processing a polarizing crystal into a thin film. Only light whose vibration direction is polarized in the direction perpendicular to the crystal passes through, while light polarized in other directions is absorbed. The crystalline polarizing unit 3 has the advantage of a high degree of polarization.

[0052] Alternatively, the polarizing unit 3 may be configured with a Glan-Thompson / Glan-Taylor prism. A Glan-Thompson / Glan-Taylor prism is configured by combining, for example, two prisms. When light is reflected at the boundary surface of the prisms, the polarization direction rotates in an orthogonal direction. By combining two prisms, the vibration direction of the light can be aligned in an orthogonal direction.

[0053] Alternatively, the polarizing unit 3 may have an optical multilayer film such as a polarizing beam splitter (PBS). By combining multilayer films with different refractive indices depending on the wavelength of light, it is possible to pass only light of a specific polarization state. A polarizing unit 3 made of an optical multilayer film has the advantage of being usable over a wide bandwidth.

[0054] Alternatively, the polarizing unit 3 may contain dye or iodine. The dye used has the property that its absorption rate varies depending on the direction of light vibration. By processing this dye into a thin film, it is possible to absorb only light with a specific polarization direction. Dyes have the advantage of being highly durable.

[0055] Alternatively, the polarizing unit 3 may contain iodine. The polarizing unit 3 is made by uniformly applying iodine to a base material such as polyvinyl alcohol (PVA). A polarizing unit made in this manner has the advantage of having a high degree of polarization.

[0056] Alternatively, the polarizing unit 3 may contain an inorganic material. For example, the polarization state of light can be controlled by utilizing surface plasmons induced in metal nanoparticles or a metal uneven structure. A polarizing unit 3 containing an inorganic material has the advantage of being highly durable.

[0057] The above description of the imaging element according to the second embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0058] 3. Third Embodiment of the Present Technology (Example 3 of Image Sensor) The image sensor 10 according to an embodiment of the present technology may further include an optical system that causes incident light to be incident substantially perpendicularly on the polarization sensor 2. This will be described with reference to Fig. 7. Fig. 7 is a schematic diagram showing an example configuration of the image sensor 10 according to an embodiment of the present technology.

[0059] 7, the image sensor 10 includes an optical system 4. The optical system 4 directs incident light to the polarization sensor 2 at a substantially normal angle. This prevents incident light from being obliquely incident on the polarization sensor 2. As a result, the polarization sensor 2 can perform measurements with high accuracy.

[0060] The configuration of the optical system 4 is not particularly limited, but for example, a telecentric lens or the like can be used. A telecentric lens is a lens designed to receive light incident parallel to the optical axis and emit it parallel to the optical axis.

[0061] In addition to the telecentric lens, for example, a collimator lens or a prism may be used in the optical system 4 .

[0062] The above description of the imaging element according to the third embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0063] 4. Fourth Embodiment of the Present Technology (Fourth Example of Image Sensor) The image sensor 10 according to an embodiment of the present technology may further include a wavelength selection unit that selects a wavelength band of incident light that is incident on the phase difference adjustment unit 1. This will be described with reference to Fig. 8. Fig. 8 is a schematic diagram showing a configuration example of the image sensor 10 according to an embodiment of the present technology.

[0064] 8, the image sensor 10 further includes a wavelength selection unit 5 that selects the wavelength band of the incident light that enters the phase difference adjustment unit 1. The wavelength selection unit 5 can transmit only light in a specific wavelength band. This allows the wavelength band that the polarization sensor 2 measures to be narrowed.

[0065] In this configuration example, the wavelength selection unit 5, the polarization unit 3, the phase difference adjustment unit 1, and the polarization sensor 2 are arranged in this order, but the order of the respective components is not particularly limited. The same applies to the other embodiments.

[0066] This will be described with reference to Figures 9 and 10. Figures 9 and 10 are graphs showing an example of the characteristics of light received by the polarization sensor 2 according to an embodiment of the present technology. The horizontal axis represents wavelength, and the vertical axis represents intensity (sensitivity). The wavelength changes continuously. The gray shaded area represents the wavelength band of light that was not transmitted by the wavelength selection unit 5.

[0067] 9 shows the characteristics of the first region 21, which strongly detects light with a polarization direction of 0 degrees. As shown in Fig. 9, because a portion of the light is excluded by the wavelength selection unit 5, it is easy to identify the light with a wavelength of 400 nm, which has the highest intensity.

[0068] 10 shows the characteristics of the third region 23, which strongly detects light with a polarization direction of 90 degrees. As shown in Fig. 10, because a portion of the light is excluded by the wavelength selection unit 5, it is easy to identify the light with a wavelength of 800 nm, which has the highest intensity.

[0069] In this way, by further providing the wavelength selection unit 5, the wavelength band to be measured is narrowed, and the measurement accuracy of the image sensor 10 is improved.

[0070] The configuration of the wavelength selection unit 5 is not particularly limited, but for example, a bandpass filter or the like can be used. A bandpass filter is a filter that transmits only light in a specific wavelength band and blocks light of other wavelengths.

[0071] In addition to the bandpass filter, for example, a bandcut filter, a lowpass filter, a highpass filter, or the like may be used in the wavelength selection unit 5 .

[0072] The above description of the imaging element according to the fourth embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0073] 5. Fifth Embodiment of the Present Technology (Fifth Example of Image Sensor) The image sensor 10 according to an embodiment of the present technology may further include a depolarization unit 6 that depolarizes polarization included in incident light that is incident on the polarization unit 3. This will be described with reference to Fig. 11. Fig. 11 is a schematic diagram showing a configuration example of the image sensor 10 according to an embodiment of the present technology.

[0074] As shown in Fig. 11, the image sensor 10 further includes a depolarization unit 6 that eliminates the polarization contained in the incident light that enters the polarization unit 3. For example, the influence of polarization may increase as the angle of incident light increases. Alternatively, polarized light is also contained in natural light. The depolarization unit 6 can eliminate the influence of such polarization.

[0075] A reflective or absorptive circular polarizer can be used as an example of the configuration of the depolarization unit 6. By using circularly polarized light, it is possible to apparently depolarize the light.

[0076] Alternatively, an axial dielectric crystal can be used as a configuration example of the depolarization unit 6. The polarization state of an axial dielectric crystal can be changed over time by applying an alternating voltage. By changing the polarization state at a frequency that is sufficiently fast compared to the imaging time, the polarization of the incident light can be depolarized.

[0077] The above description of the imaging element according to the fifth embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0078] 6. Sixth Embodiment of the Present Technology (Sixth Example of Image Sensor) The image sensor 10 according to an embodiment of the present technology may further include a high retardation portion 7 that imparts a phase difference to incident light that is incident on the polarizing portion 3. This will be described with reference to Fig. 12. Fig. 12 is a schematic diagram showing a configuration example of the image sensor 10 according to an embodiment of the present technology.

[0079] 12 , the imaging element 10 may further include a high retardation portion 7 that imparts a phase difference to the incident light that is incident on the polarizing portion 3. The high retardation portion 7 can cancel the polarization state of the light by changing the phase of the incident light.

[0080] As an example of the configuration of the high retardation portion 7, for example, multiple phase plates can be combined. Each phase plate changes the phase of light depending on the polarization state of the light. When polarized light is incident on a phase plate that is sufficiently large relative to the wavelength, it is possible to create light that has a phase difference of 180 degrees for every wavelength of several nanometers, for example. Considering the wide wavelength band used for measurement, this light has many polarization states, making it possible to eliminate the effects of specific polarization.

[0081] The above description of the imaging element according to the sixth embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0082] 7. Seventh Embodiment of the Present Technology (Example of Imaging Device) An imaging device according to an embodiment of the present technology includes: a phase difference adjusting unit that applies a phase difference to polarized incident light that varies depending on the wavelength band of the incident light; a polarization sensor that acquires optical information from the phase difference adjusting unit; and a calculation unit that calculates the optical information.

[0083] An imaging device 100 according to an embodiment of the present technology will be described with reference to Fig. 13. Fig. 13 is a block diagram showing an example configuration of the imaging device 100 according to an embodiment of the present technology.

[0084] As shown in FIG. 13, the imaging device 100 includes a phase difference adjusting unit 1, a polarization sensor 2, and a calculation unit 8.

[0085] The phase difference adjustment unit 1 imparts different phase differences to polarized incident light depending on the wavelength band of the incident light.

[0086] The polarization sensor 2 acquires optical information from the phase difference adjusting unit 1 .

[0087] The calculation unit 8 calculates the optical information obtained by the polarization sensor 2. For example, it is difficult to completely separate light according to the polarization state, and light with a polarization direction of 0 degrees is received most strongly by the first region 21, which is sensitive to a polarization direction of 0 degrees, but is also received by the second region 22, which is sensitive to a polarization direction of 30 degrees, although with a lower intensity. The calculation unit 8 performs calculations to remove these effects, thereby correcting the measurement results. As a result, measurement accuracy is improved.

[0088] The calculation unit 8 is configured by, for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc. The calculation unit 8 realizes functions by, for example, reading a program.

[0089] The above description of the imaging device according to the seventh embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0090] It should be noted that the embodiments of the present technology are not limited to the above-described embodiments, and various modifications are possible within the scope of the present technology. The specific numerical values, shapes, materials (including compositions), etc. described in each embodiment are merely examples, and the present technology is not limited to these.

[0091] The present technology may also have the following configurations. [1] An imaging element including a phase difference adjustment unit that applies a phase difference to polarized incident light that varies depending on the wavelength band of the incident light, and a polarization sensor that acquires optical information from the phase difference adjustment unit. [2] The imaging element according to [1], in which the polarization sensor has a plurality of regions that have different sensitivities depending on the polarization direction. [3] The imaging element according to [1] or [2], in which the phase difference adjustment unit is configured to be separable from the polarization sensor. [4] The imaging element according to any one of [1] to [3], in which the phase difference adjustment unit includes a resin film. [5] The imaging element according to any one of [1] to [4], in which the phase difference adjustment unit includes a crystalline material or an optical multilayer film. [6] The imaging element according to any one of [1] to [5], in which the imaging element includes a plurality of the phase difference adjustment units. [7] The imaging element according to any one of [1] to [6], further including a polarizing unit that polarizes incident light. [8] The imaging element according to [7], in which the polarizing unit includes a dye. [9] The image sensor according to [7], wherein the polarizing section contains iodine.

[10] The image sensor according to [7], wherein the polarizing section has an optical multilayer film.

[11] The image sensor according to any one of [1] to

[10] , further comprising an optical system that causes the incident light to be incident on the polarization sensor approximately perpendicularly.

[12] The image sensor according to any one of [1] to

[11] , wherein the incident light that enters the phase difference adjustment section includes near-infrared light or visible light.

[13] The image sensor according to any one of [1] to

[12] , further comprising a wavelength selection section that selects a wavelength band of the incident light that enters the phase difference adjustment section.

[14] The image sensor according to any one of [7] to

[13] , further comprising a depolarization section that depolarizes the polarization included in the incident light that enters the polarizing section.

[15] The image sensor according to any one of [7] to

[14] , further comprising a high retardation section that imparts a phase difference to the incident light that enters the polarizing section.

[16] An imaging device comprising: a phase difference adjustment unit that applies a phase difference to polarized incident light that varies depending on the wavelength band of the incident light; a polarization sensor that acquires optical information from the phase difference adjustment unit; and a calculation unit that calculates the optical information.

[0092] REFERENCE SIGNS LIST 10 imaging element 1 phase difference adjustment section 2 polarization sensor 3 polarization section 4 optical system 5 wavelength selection section 6 depolarization section 7 high phase difference section 8 calculation section 100 imaging device

Claims

1. An imaging device comprising: a retardation adjustment unit that provides a retardation to polarized incident light, the retardation being different according to the wavelength band of the incident light; and a polarization sensor that acquires optical information from the retardation adjustment unit.

2. The imaging device according to claim 1, wherein the polarization sensor has a plurality of regions with different sensitivities according to the polarization direction.

3. The imaging device according to claim 1, wherein the retardation adjustment unit is configured to be separable from the polarization sensor.

4. The imaging device according to claim 1, wherein the retardation adjustment unit has a resin film.

5. The imaging device according to claim 1, wherein the retardation adjustment unit has a crystal material or an optical multilayer film.

6. The imaging device according to claim 1, comprising a plurality of the retardation adjustment units.

7. The imaging device according to claim 1, further comprising a polarization unit that polarizes incident light.

8. The imaging device according to claim 7, wherein the polarization unit contains a dye.

9. The imaging device according to claim 7, wherein the polarization unit contains iodine.

10. The imaging device according to claim 7, wherein the polarization unit has an optical multilayer film.

11. The imaging device according to claim 1, further comprising an optical system that makes the incident light enter the polarization sensor substantially perpendicularly.

12. The imaging device according to claim 1, wherein the incident light entering the retardation adjustment unit includes near-infrared light or visible light.

13. The imaging device according to claim 1, further comprising a wavelength selection unit that selects the wavelength band of the incident light entering the retardation adjustment unit.

14. The imaging device according to claim 7, further comprising a depolarization unit that depolarizes the polarization included in the incident light entering the polarization unit.

15. The imaging device according to claim 7, further comprising a high-retardation unit that provides a retardation to the incident light entering the polarization unit.

16. An imaging apparatus comprising: a retardation adjustment unit that provides a retardation to polarized incident light, the retardation being different according to the wavelength band of the incident light; a polarization sensor that acquires optical information from the retardation adjustment unit; and an arithmetic unit that calculates the optical information.

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