JP7265195B2 - Color image sensor and imaging device - Google Patents

Description

The present invention relates to a color imaging device and an imaging apparatus having the color imaging device.

2. Description of the Related Art In general, in an imaging device equipped with a photoelectric conversion element such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor, it is necessary to perform color separation of incident light in order to acquire color information of an imaging target.

FIG. 16 shows a sectional view of a conventional color imaging device. In a conventional color imaging device 600, a photoelectric conversion element 602 is arranged on an electric wiring 601, and a subtractive color filter 604 made of an organic material or an inorganic multilayer material is arranged facing each pixel including the photoelectric conversion element 602. be done. A microlens 605 is arranged above the color filter 604 .

When light is incident from the microlens 605, the color filter 604 is used to transmit only the light in the desired wavelength band and absorb or reflect the light in the unnecessary wavelength band, thereby red (R) and green light for each pixel. By acquiring signals from the three photoelectric conversion elements 602 corresponding to (G) and blue (B), a color two-dimensional image can be generated.

However, in the general color image sensor 600 as described above, when the incident light has a ratio of RGB of 1:1:1, the total amount of light after passing through the color filter 604 is inevitably reduced to about 1/3. There is a problem of putting away. The rest of the lost light is lost due to absorption or reflection and cannot reach the photoelectric conversion element 602 . Therefore, the light utilization efficiency of incident light is about 30% at maximum, and the sensitivity of the imaging device is greatly limited. In recent years, when pixels are getting finer and finer, the amount of light received by one pixel is decreasing.

Therefore, instead of the color filter 604, it has been proposed to configure a color imaging device using a spectroscopic element such as a microprism or a dichroic mirror that can split incident light according to the wavelength band. Such an approach can, in principle, greatly reduce the loss of incident light and greatly improve the efficiency of light utilization. However, it is difficult to integrate such elements on a photoelectric conversion element in recent years as pixels are becoming finer.

Therefore, in recent years, it has been proposed to construct a color imaging device using a spectroscopic device having a fine structure that can be relatively easily integrated on a photoelectric conversion device. Non-Patent Document 1 proposes a method of improving light utilization efficiency by eliminating light loss in color separation in principle by using two types of microstructures capable of separating incident light into two wavelength regions. ing.

FIG. 17(a) shows a top view of a color imaging device using a conventional spectroscopic device, FIG. 17(b) shows its XVIIb-XVIIb sectional view, and FIG. 17(c) shows its XVIIc-XVIIc A cross-sectional view is shown. As shown in the figure, the color image sensor 610 has fine beam structures 606-1 and 606-2 arranged corresponding to the pixels 602 instead of the color filters 604, and the incident light is Separates straight light and deflected light. This is because the phase retardation effect felt by the incident light in and around the fine beam structure differs greatly in one wavelength region and is almost equal in the other wavelength region.

Therefore, by alternately arranging two types of fine beam structures 606-1 and 606-2 having different structural thicknesses on a two-dimensional pixel array for each row, four photoelectric conversion elements 602 adjacent to each other It becomes possible to receive light having different wavelength components. As a result, color information can be generated by matrix calculation using photoelectric conversion signals output from the photoelectric conversion elements 602 .

Furthermore, in Non-Patent Document 1, as shown in FIG. 18, light utilization efficiency is improved by arranging a staircase-shaped fine structure 607 capable of separating incident light into three wavelength regions on a pixel 602. A color imaging device 620 is also proposed at the same time. In this method, in addition to the generation of color information by matrix operation as described above, the light of the separated three wavelength regions can be made incident on each of the three adjacent photoelectric conversion elements 602. Therefore, the output from each photoelectric conversion element 602 is It is believed that the resulting photoelectric conversion signal can be used to directly generate color information.

Seiji Nishiwaki, Tatsuya Nakamura, Masao Hiramoto, Toshiya Fujii and Masa-aki Suzuki, “Efficient color splitters for high-pixel-density image sensors,” Nature Photonics, Vol. 7, March 2013, pp. 240-246

However, the technology disclosed in Non-Patent Document 1 has practical problems.

First, in the method using the microstructures 606-1 and 606-2 for separating the incident light into two wavelength regions, the two types of microstructures 606-1 and 606-2 have different structural heights, so the manufacturing process costs increases. In addition, since the microstructures 606-1 and 606-2 have a beam structure with a long axis, the phase retardation effect that the light senses differs depending on the polarization direction of the incident light, and the color separation function is polarization dependent. There is a problem that there exists Furthermore, since signal processing is performed from light intensity data separated into two sets of two wavelength regions to restore RGB information, there is concern about color reproducibility.

On the other hand, according to the method using the staircase-shaped fine structure 607 that separates the incident light into three wavelength regions, the light utilization rate is certainly high and a color image with good color reproducibility can be theoretically obtained. It is difficult to fabricate a microstructure 607 with The disclosed staircase-shaped fine structure 607 requires multiple lithography and etching processes, as well as high-precision alignment technology in the lithography process, which increases the manufacturing cost. Further, like the fine structures 606-1 and 606-2 that separate incident light into two wavelength regions, the shape of the fine structure 607 is a beam structure having a long axis, so the color separation function has polarization dependence. There is a problem of

The present invention has been made in view of the above problems, and an object of the present invention is to provide a microscopic spectroscopic element that can be easily manufactured, has little polarization dependence, and can separate incident light into three wavelength regions. An object of the present invention is to provide a high-sensitivity color imaging element and an imaging device integrated facing an array.

In order to solve the above-described problems, one aspect of the present invention provides a color imaging device, a two-dimensional pixel array in which a plurality of pixels each including a photoelectric conversion device are arranged in a two-dimensional array on a substrate; A transparent layer formed on a two-dimensional pixel array, and a two-dimensional spectral element array in which a plurality of spectral elements are arranged in a two-dimensional array inside or on the transparent layer, each of the spectral elements and a set of microstructures comprising a plurality of microstructures made of a material having a refractive index higher than that of the transparent layer, wherein the set of microstructures is aligned with the two-dimensional pixel array. a plurality of microstructures having the same length in the vertical direction, different shapes in the horizontal direction with respect to the two-dimensional pixel array, and arranged at intervals equal to or less than the wavelength of incident light, wherein the spectroscopic element at least part of the light incident on is separated into first to third polarized lights with different propagation directions depending on the wavelength and emitted from the spectroscopic element, which are arranged continuously in one direction of the two-dimensional pixel array. It is characterized in that the light is incident on each of the three pixels arranged as above.

In another aspect of the present invention, the microstructure is a columnar structure in which the bottom surface and the top surface of the structure have four-fold rotational symmetry with respect to the center as the axis of symmetry.

Another aspect of the present invention is characterized in that the first to third polarized light beams are incident on the first to third photoelectric conversion elements of three consecutive adjacent pixels, respectively.

In another aspect of the present invention, when the incident light is white light, the light incident on the first photoelectric conversion element has a light intensity peak in a blue wavelength region of 500 nm or less, and the second The light incident on the photoelectric conversion element has a light intensity peak in a green wavelength range of 500 nm to 600 nm, and the light incident on the third photoelectric conversion element has a light intensity in a red wavelength range of 600 nm or more. It is characterized by having a peak.

In another aspect of the present invention, the shape of the set of fine structures is the same in all of the spectroscopic elements forming the two-dimensional spectroscopic element array.

In another aspect of the present invention, the directions of the pair of microstructures of the adjacent spectroscopic elements arranged along the first direction of the two-dimensional spectroscopic element array are alternately reversed, The three consecutive pixels are arranged along the first direction, and among the three adjacent pixels along the first direction, two pixels on both outer sides are arranged along the first direction. Any one of the first to third polarized lights is incident from the two spectroscopic elements that are adjacent along the direction.

In another aspect of the present invention, between the two-dimensional pixel array and the two-dimensional spectroscopy element array, there is a first color filter having a transmittance peak in a blue wavelength region with a wavelength of 500 nm or less, and green with a wavelength of 500 nm to 600 nm. At least one of a second color filter having a transmittance peak in a wavelength range and a third color filter having a transmittance peak in a red wavelength range of 600 nm or more is arranged in an array. It is characterized by further comprising an arranged color filter array.

Another aspect of the present invention is an imaging apparatus comprising: a color imaging device according to one aspect of the present invention; an imaging optical system for forming an optical image on an imaging surface of the color imaging device; and the color imaging device. and a signal processing unit that processes an electrical signal output by the.

According to the present invention, a color image pickup device and an image pickup device with high light utilization efficiency are provided by using a minute spectroscopic element that can be easily manufactured, has little polarization dependence, and can separate incident light into three wavelength regions. It can be manufactured more easily than before.

1 is a side view showing a schematic configuration of an imaging device of the present invention; FIG. FIG. 3 is a diagram schematically showing a part of the cross section of the pixel array and the spectroscopic element array of the imaging device according to Embodiment 1 of the present invention; 1A is a top view of a schematic configuration of part of an imaging device according to Embodiment 1 of the present invention, and FIG. 1B is a cross-sectional view thereof; FIG. (a) is a top view of a columnar structure constituting a minute spectroscopic element of the imaging device according to Embodiment 1 of the present invention, and (b) is a cross-sectional view thereof. (a) is a cross-sectional view of an example of a minute spectroscopic element of an imaging device according to Embodiment 1 of the present invention, and (b) is a diagram showing phase delay distributions of three wavelengths separated by the minute spectroscopic element. be. (a) is a top view of an example of a minute spectroscopic element of the imaging device according to Embodiment 1 of the present invention, and (b) is a cross-sectional view thereof. (a) shows, in the imaging device according to Embodiment 1 of the present invention, when parallel light having vertical polarization is incident from the upper surface of the columnar structure, it propagates separately in three directions from the output end of the minute spectroscopic device. FIG. 4B is a diagram showing the wavelength dependence of the efficiency, and (b) shows the efficiency of propagation in three directions separated from the output end of the micro spectroscopic element when horizontally polarized parallel light is incident from the upper surface of the columnar structure. is a diagram showing the wavelength dependence of . 4(a) to 4(h) are diagrams showing structural pattern examples of the minute spectroscopic element of the imaging device according to Embodiment 1 of the present invention. FIG. 4(a) to 4(c) are diagrams schematically showing the arrangement of pixels corresponding to color components of the imaging element according to Embodiment 1 of the present invention. FIG. 4(a) to 4(c) are diagrams schematically showing the arrangement of pixels corresponding to color components of the imaging element according to Embodiment 1 of the present invention. FIG. FIG. 4 shows a cross-sectional view of a schematic configuration of an imaging device that is a modification of Embodiment 1 of the present invention. (a) is a top view of a schematic configuration of part of an imaging device according to Embodiment 2 of the present invention, and (b) is a cross-sectional view thereof. FIG. 7 is a diagram schematically showing the arrangement of pixels of an imaging device according to Embodiment 2 of the present invention; (a) is a top view of a schematic configuration of part of an imaging device according to Embodiment 3 of the present invention, and (b) is a cross-sectional view thereof. (a) is a top view of a schematic configuration of part of an imaging device according to Embodiment 4 of the present invention, and (b) is a cross-sectional view thereof. 1 is a cross-sectional view of a conventional color imaging device; FIG. (a) is a top view of a color imaging device using a conventional spectroscopic device, (b) is its XVIIb-XVIIb cross-sectional view, and (c) is its XVIIc-XVIIc cross-sectional view. FIG. 4 is a cross-sectional view of another color imaging device using a conventional spectroscopic device;

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the following embodiments are merely examples, and it goes without saying that the present invention is not limited to these embodiments.

FIG. 1 is a side view showing a schematic configuration of an imaging device of the present invention. The imaging device 10 includes a lens optical system 11, an imaging device 12 including a photoelectric conversion device such as a CCD or CMOS, and a signal processing unit 13 that processes a photoelectric conversion signal output from the imaging device 12 to generate an image signal. .

Light such as natural light or illumination light is incident on the object 1 , and the light transmitted/reflected/scattered by this or the light emitted from the object 1 forms an optical image on the imaging element 12 by the lens optical system 11 . In general, the lens optical system 11 is composed of a lens group consisting of a plurality of lenses arranged along the optical axis in order to correct various optical aberrations. showing. The signal processing unit 13 also has an image signal output for sending out the generated image signal to the outside.

Note that the imaging apparatus 10 of the present invention may include known components such as an optical filter for cutting infrared light, an electronic shutter, a viewfinder, a power supply (battery), a flashlight, etc., but the description thereof is not intended for understanding the present invention. is omitted because it is not particularly necessary for Moreover, the above configuration is merely an example, and in the present invention, known elements can be appropriately combined and used for the constituent elements other than the lens optical system 11, the image sensor 12, and the signal processing section 13.

Before describing specific embodiments of the present invention, an outline of the imaging element 12 in the embodiments of the present invention will be described.

The imaging element 12 according to the embodiment of the present invention includes a pixel array in which a plurality of cells (pixels) 102 including photoelectric conversion elements are arranged two-dimensionally, and a spectral element array in which a plurality of microscopic spectral elements 101 are arranged two-dimensionally. and FIG. 2 is a diagram schematically showing a part of the cross section of the pixel array and the spectroscopic element array of the imaging device according to Embodiment 1 of the present invention. The spectral element array faces the pixel array and is arranged on the side on which light from the lens optical system is incident. Each micro spectroscopic element 101 is composed of a plurality of columnar structures having a constant thickness. Although the micro spectroscopic element 101 is represented by four columnar structures for convenience, there are no restrictions on the number, spacing, and arrangement pattern, and various arrangement forms are possible.

The visible light components included in the light incident on the imaging device 12 are classified into first color component, second color component, and third color component for each wavelength region. The combination of the first to third color components is generally a combination of the three primary colors of red (R), green (G), and blue (B). It is not limited to this.

The microscopic spectroscopic element 101 according to the embodiment of the present invention utilizes the phase delay effect and its structural size dependence/wavelength dependence, which will be described later, according to the above-described first to third color components. and spatially separate them on the pixel array. That is, in the embodiment of the present invention, at least part of the light that has entered the image pickup device changes its propagation direction according to the color component by the minute spectroscopic device 101 and enters the plurality of pixels 102 . Therefore, by appropriately setting the distance between the minute spectroscopic element 101 and the pixel 102, the light separated into three wavelength ranges can be received by the different pixels 102, respectively.

When light is incident on the pixel 102, the photoelectric conversion element outputs an electrical signal (photoelectric conversion signal) corresponding to the intensity of the incident light. It can be obtained using arithmetic. Since the micro spectroscopic element 101 and the plurality of pixels 102 corresponding to the micro spectroscopic element 101 are arranged two-dimensionally, it is possible to acquire color information of the optical image of the object formed by the lens optical system 11. can.

In Embodiments 1 and 2, which will be described later, by using the microlens array, almost all of the incident light is transmitted through any one of the micro-spectroscopic elements 101 constituting the spectroscopic element array, so that almost all of the incident light is are separated into three wavelength bands and enter the pixel array. Therefore, the color information can be obtained directly from the photoelectric conversion signal or using a simple calculation.

In Embodiments 3 and 4, which will be described later, part of the incident light passes through the microscopic spectroscopic elements 101 that constitute the spectroscopic element array, so that part of the incident light is separated into three wavelength bands. incident on the pixel array. Therefore, part of each pixel 102 outputs a photoelectric conversion signal corresponding to the total light intensity of the light separated into three wavelength bands and the light not separated. Color information can be obtained by using an appropriate matrix operation, which will be described later, on the output photoelectric conversion signal.

According to the image sensor 12 of the embodiment of the present invention, color information can be obtained by low-loss light separation into three colors using the minute spectral element 101 without using a subtractive color filter. Therefore, the total amount of light reaching the pixel array can be increased compared to an image sensor using color filters, and the imaging sensitivity can be enhanced. Furthermore, the micro spectroscopic element 101 is composed of a structure with a constant thickness that is easy to fabricate, and the symmetry of the top and bottom surfaces of the structure does not cause polarization dependence. It is possible to solve the problem of polarization dependence in the color separation function in the prior art.

Hereinafter, more specific embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The outline of the configuration of the imaging device according to the first embodiment will be described below.

FIG. 3(a) is a top view of a schematic configuration of part of the imaging device according to Embodiment 1 of the present invention, and FIG. 3(b) is a cross-sectional view thereof. The imaging device 100 according to the first embodiment has a two-dimensional pixel array in which pixels ₁₀₂ including photoelectric conversion elements are arranged in an array. A lens 103 is laminated. Inside the low-refractive-index transparent layer 111, a plurality of thicknesses (the length in the direction perpendicular to the two-dimensional pixel array) made of a material such as SiN having a higher refractive index than the transparent layer 111 is provided. A minute spectroscopic element 101 made of a certain fine structure is embedded. For convenience, in the following description, the normal direction of the two-dimensional pixel array is the z-axis, the direction parallel to the two-dimensional pixel array, and the direction in which the three pixels 102 constituting the pixel unit 110 are arranged is the x-axis, parallel to the two-dimensional pixel array. , an xyz orthogonal coordinate system is set in which the y-axis is the direction perpendicular to the x-axis.

As shown in the figure, microlenses 103, microscopic spectroscopic elements 101, and pixels 102 are arranged in a lattice pattern on the xy plane, and one microscopic spectroscopic element 101 is arranged on the central axis of each microlens 103. It is Assuming that three pixels adjacent in the x-axis direction constitute one pixel unit 110, each microlens 103 adjacent in the x-axis direction corresponds to the pixel unit 110 on a one-to-one basis, and the central axis of each microlens 103 corresponds. It passes through approximately the center of the central pixel 102 of the pixel unit. That is, one micro lens 103 and one micro spectroscopic element 101 correspond to three pixels 102 adjacent to each other in the x-axis direction, and the micro lens 103, micro spectroscopic element 101, and pixel unit 110 are combined into one. Assuming that the imaging element units are used, the imaging element units are arranged in a grid pattern on the xy plane.

In the above description, as an example, a two-dimensional pixel array arranged in an orthogonal grid pattern has been described. may be of any arrangement, shape, or size. Also, although omitted in FIGS. 3A and 3B, between the two-dimensional pixel array and the microstructure, it operates as an internal microlens, allowing light from the microscopic spectroscopic element 101 to enter the pixel 102. A high-refractive-index concavo-convex structure made of SiN or the like, which serves to guide the photoelectric conversion element, may be provided. The structures shown in FIGS. 3(a) and 3(b) can be fabricated by known semiconductor manufacturing techniques.

Note that the imaging device 100 shown in FIGS. 3A and 3B has a back-illuminated structure that receives light from the opposite side of the wiring layer 112, but the present embodiment is not limited to such a structure. It may have a surface irradiation type structure in which light is received from the wiring layer 112 side.

The function of each component of the imaging device 100 according to this embodiment will be described below.

White light incident on the imaging device 100 is first condensed by the microlens array, and almost all the light passes through the minute spectroscopic device 101 corresponding to each microlens 103 . Light is spatially separated into three wavelength bands in the xz plane by each micro spectroscopic element 101 and received by three pixels 102 directly below each micro spectroscopic element 101 . In the example shown in FIG. 3B, each minute spectral element 101 directs the light of the first color component (R) in the first direction (right) and the light of the second color component (G) in the second direction. (straight ahead ₎ , the light of the third color component (B) propagates in the third direction (left) _. D _B (left) corresponds to detection of R, G, and B color information, respectively.

Note that the above is _just an example, and depending on the configuration of each micro-spectroscopic element 101, the combination of the color component and the propagation direction can be freely changed _. D _B is also changed.

When the light spatially separated into three wavelength ranges is received by each of the three pixels 102, photoelectric conversion is performed by the photoelectric conversion element in each pixel 102, and an image signal containing color information is output.

Note that the widths w _d1 , w _d2 , and w _d3 in the x-axis direction of the three pixels 102D _R , D _G , and D _B immediately below each minute spectroscopic element 101 may be the same or different. Along with this, the width w _lx in the x-axis direction and the width w _ly in the y-axis direction of the microlens 103 may be the same or different. In the example of FIG. 3, the widths w _d1 , w _d2 , and w _d3 in the x-axis direction of the three pixels 102D _R , D _G , and D _B are the same, and the microlenses 103 have w _lx and w _ly different.

Between the pixel unit 110 and the minute spectroscopic element 101, a concave-convex structure with a high refractive index made of SiN or the like that operates as an internal microlens can be provided. can have a lens function, it is also possible to omit the internal microlens.

The minute spectroscopic element in this embodiment will be described below.

The minute spectroscopic element 101 in Embodiment 1 is composed of a plurality of minute columnar structures 121 . FIG. 4(a) is a top view of a columnar structure constituting a minute spectroscopic element of the imaging device according to Embodiment 1 of the present invention, and FIG. 4(b) is a cross-sectional view thereof. The columnar structure 121 is made of a material such as SiN having a refractive index n ₁ higher than the refractive index n ₀ of the transparent layer 111, and the thickness h of the structure is constant.

Also, the bottom and top surfaces of the columnar structure 121 are square. This columnar structure 121 functions as an optical waveguide for confining light within the structure and propagating it due to the difference in refractive index from the transparent layer 111 . Therefore, when light is incident from the top side, the light propagates while being strongly confined within the columnar structure 121, undergoes a phase delay effect determined by the effective refractive index n _eff of the optical waveguide, and is output from the bottom side. be done. Specifically, when the phase of light propagating through the transparent layer 111 for a length corresponding to the thickness of the columnar structure 121 is used as a reference, the phase delay amount φ due to the columnar structure 121 is λ Given that
φ=(n _eff −n ₀ )×2πh/λ (1)
is represented by Since the amount of phase delay varies depending on the wavelength λ of light, different amounts of phase delay can be given to the light incident on the same columnar structure 121 according to the wavelength range (color component). Further, since the bottom and top surfaces of the columnar structures 121 are square, even when the polarization direction is changed, the optical characteristics including the phase retardation effect do not change. Furthermore, n _eff is known to be a function of feature size and takes values n ₀ <n _eff <n ₁ . Therefore, in the examples shown in FIGS. 4A and 4B, by changing the width w of the columnar structure 121, it is possible to set an arbitrary phase delay amount.

The cross-sectional view of FIG. 5(a) is an example of the minute spectroscopic element 101 according to Embodiment 1, in which two columnar structures 121-1 and 121-2 are arranged in the x-axis direction. In the y-axis direction, a plurality of columnar structures 121-1 and 121-2 are arranged at intervals equal to or less than the wavelength.

As shown in FIG. 5A, the columnar structures 121-1 and 121-2 adjacent in the x-axis direction have different widths w. Due to the difference in the width w, it is possible to give a different phase delay distribution for each wavelength region to the light transmitted through the microscopic spectroscopic element 101, thereby changing the light wavefront. Since the propagation direction (deflection direction) of light is determined by this light wavefront, it is possible to spatially separate the light transmitted through the microscopic spectroscopic element 101 according to the wavelength regions (color components). That is, the micro spectroscopic element 101 according to Embodiment 1 has a plurality of columnar structures 121, and changes the dimension w of the adjacent columnar structures 121-1 and 121-2 in a plane orthogonal to the light propagation direction. Thus, different light wavefronts are given according to the wavelength regions of the incident light, and the color components are spatially separated.

For example, in the case of the structure shown in FIG. 5(a), different phase delay distributions can be given according to three wavelengths (for example, wavelengths corresponding to RGB), as shown in FIG. 5(b). In this example, the phase delay distribution of the wavelength corresponding to the first color component light (R) is along a straight line in which the phase amount linearly increases from 0 to +2π, and corresponds to the second color component light (G). The phase delay distribution of the wavelength corresponding to the third color component light (B) does not change spatially, and the phase delay distribution of the wavelength corresponding to the third color component light (B) follows a straight line in which the phase amount linearly decreases from 0 to -2π. In this case, as shown in FIG. 5A, the light transmitted through the minute spectral element 101 is such that the light of the first color component (R) travels in the first direction (right) and the light of the second color component (G ) can efficiently propagate in the second direction (straight), and the light of the third color component (B) can efficiently propagate in the third direction (left).

Note that the above description is an example, and depending on the dimensions of each columnar structure 121, the combination of the color component and the deflection direction can be freely changed. For example, the light of the first color component (R) travels in the second direction (straight ahead), the light of the second color component (G) travels in the first direction (right), and the light of the third color component (B) travels in the first direction (right). They can each efficiently propagate in the third direction (left).

A more detailed example of the minute spectroscopic element 101 in this embodiment will be described.

FIG. 6(a) is a top view of an example of a minute spectroscopic element of the imaging device according to Embodiment 1 of the present invention, and FIG. 6(b) is a cross-sectional view thereof. Two columnar structures 121-1 and 121-2 having different widths w ₁ and w ₂ and constant thicknesses (lengths in the direction perpendicular to the two-dimensional pixel array) are arranged in the x-axis direction. , three identical columnar structures 121 - 1 and 121 - 2 are arranged in the y-axis direction, and the above are regarded as one micro spectroscopic element 101 . SiN (n ₁ =2.03) is assumed for the material forming the columnar structures 121-1 and 121-2, and SiO ₂ (n ₀ =1.45) is assumed for the material forming the transparent layer. , the case where the bottom and top are square. Further, the thickness h of all the columnar structures 121-1 and 121-2 is 1200 nm, the width _w1 of the columnar structure 121-1 on the left side of the pattern is 145 nm, and the width _w2 of the columnar structure 121-2 on the right side of the pattern is 340 nm, and the distance p between the columnar structures 121-1 and 121-2 in the x-axis and y-axis directions was 450 nm.

7A and 7B show, in the structure described above, when parallel light is incident from the upper surfaces of the columnar structures 121-1 and 121-2, three directions from the output end of the minute spectroscopic element 101 ( Wavelength dependence (calculation results based on strict coupled wave theory) of efficiency (ratio of light intensity in each propagation direction to incident light intensity) of separately propagating in each direction of b) R, G, and B) is shown. FIG. 7(a) shows the results when vertically polarized light in FIG. 6(a) is incident, and FIG. 7(b) is the result when horizontally polarized light in FIG. 6(a) is incident. In the calculation, it was assumed that the above microscopic spectroscopic elements 101 were arranged at intervals of P (P=3p) in the x-axis and y-axis directions. I'm pretty sure it's not. The deflection angles θ _R , _{θ G} , and θ _B in _the three directions are based on the diffraction of light _. =λ/P.

Also, the characteristics shown in FIGS. 7A and 7B correspond to spectral sensitivity characteristics of color filters in conventional imaging devices. The results shown in FIGS. 7(a) and 7(b) show that the efficiency in the first direction (R) peaks in the red wavelength region above 600 nm, and the efficiency in the second direction (G) is green at 500-600 nm. It shows that the efficiency in the third direction (B) peaks in the blue wavelength region below 500 nm. In addition, it exhibits a good spectral performance of 40 to 60%, and its characteristics show no significant dependence on polarization. The sum of the curves R, G, and B, that is, the total transmittance is 95% or more, and almost no light loss due to scattering or reflection occurs.

The above results show that the use of the minute spectroscopic element 101 in Embodiment 1 enables highly efficient spatial separation of color components. Furthermore, in the above example, the size of the single microscopic spectroscopic element 101 is 1.35 μm square, which is equivalent to the minimum pixel size of general CCD and CMOS sensors. Therefore, it is possible to form the minute spectroscopic element 101 corresponding to the pixel unit 110 having the minimum pixel size. It is also possible to form microscopic spectroscopic elements 101 of different sizes depending on the size, number, and arrangement pattern of the columnar structures 121 .

Desired spectral characteristics can be obtained by appropriately designing the material, number, shape, size, arrangement pattern, etc. of the columnar structures 121 constituting the micro spectroscopic element 101 . As a result, as described above, it becomes possible to separate and enter only light in a desired wavelength range into individual photoelectric conversion elements, and from the photoelectric conversion signals output from the respective photoelectric conversion elements, color components corresponding to signal can be obtained.

In addition, as described above, almost no light loss occurs due to the minute spectroscopic element 101, so that the total amount of light reaching the pixel array can be dramatically increased compared to conventional imaging elements using color filters. , it is possible to increase the imaging sensitivity. Even if the spectral performance of each minute spectral element 101 is slightly different from the ideal performance described above, good color information can be obtained by correcting and calculating the acquired signals according to the degree of the difference in performance. is possible.

In addition, in the arrangement of the columnar structures 121 described above, it is desirable to arrange them at intervals equal to or less than the wavelength of light in order to prevent generation of unnecessary diffracted light due to the periodic structure.

In the above example, the case where the bottom and top surfaces of the columnar structures are square has been described, but the shape is not limited to this. In other words, if the shape surface has four-fold rotational symmetry with respect to the axis passing through the center of the bottom surface and the top surface, the dependence of the spectroscopic function on the polarization does not occur, and the operation as an optical waveguide that brings about the phase retardation effect does not occur. not lost. Therefore, it is desirable to employ a columnar structure having four-fold rotational symmetry surfaces such as squares, hollow squares, circles, hollow circles, and crosses as shown in FIGS.

In order for the respective light spatial distributions on the pixel unit 110 to be sufficiently separated from each other after the separation of the color components by the minute spectral element 101, the distance between the output terminal of the minute spectral element 101 and the photoelectric conversion element of the pixel 102 is required. is preferably 1 μm or more. On the other hand, in order to reduce the thickness of the imaging device 100 and to save material costs and process time, it is preferable that the distance between the output end of the minute spectroscopic device 101 and the photoelectric conversion device of the pixel 102 is as short as possible.

Also, in this case, since each light spatial distribution on the pixel unit 110 needs to be clearly separated from each other according to the color components in a short propagation distance, the wavefront of the light is greatly tilted and deflected by the micro spectroscopic element 101 ( It is preferable to increase the angle of bending. In order to increase the deflection angle, it is suitable that the phase delay distribution in each wavelength band formed by the micro spectroscopic element 101 varies from 0 to 2π. It is preferable that the phase delay amount has a variable range of 2π or more. Therefore, from equation (1), if the desired central wavelength in the wavelength band on the longest wavelength side of the wavelength band to be separated is λ _r , the thickness h of the columnar structure 121 is h=λ _r /(n ₁ −n ₀ ) is desirable.

The minute spectroscopic element 101 having the spectroscopic function as described above can be manufactured by carrying out thin film deposition and patterning by a known semiconductor manufacturing technique. Since the minute spectroscopic element 101 of Embodiment 1 is composed of a plurality of columnar structures 121 with a constant thickness, it can be easily manufactured at a low cost compared to the stepped structure disclosed in Non-Patent Document 1. can.

The arrangement of micro optical elements and pixels in the imaging device of this embodiment will be described below.

In the example shown in FIG. 3, the rows of the microscopic spectroscopic elements 101 arranged along the x-axis direction are repeatedly arranged along the y-axis direction without being shifted in the x-axis direction. A pattern of the minute spectroscopic elements 101 is continuously arranged along the line. In this case, in the x-axis direction, three pixels 102D _B , D _G , and D _R corresponding to the color components immediately below each minute spectral element 101 are arranged in this order from the left, and this arrangement is repeated.

Furthermore, similarly for the pixels 102, the rows of the pixels 102 arranged along the x-axis direction are repeatedly arranged along the y-axis direction without being shifted in the x-axis direction, and as a result, along the y-axis direction 3 pixels 102D _B , D _G , and D _R are continuously arranged.

FIGS. 9A to 9C schematically show the arrangement of pixels corresponding to color components of the imaging device according to Embodiment 1 of the present invention. Assuming that three pixels 102D _B , D _G , and D _R adjacent in the x-axis direction are one color pixel unit U, for the color pixel unit U ₁ and color pixel unit U ₁ shown in FIG. Both color pixel units _U2 shifted in the x-axis direction by a single pixel will necessarily contain one pixel each corresponding to R, G, and B. That is, if color information is obtained while shifting the color pixel unit U by single pixels on the xy plane, it is possible to obtain information on three colors of RGB corresponding to the number of pixels. This means that the resolution of the imaging device can be increased to the extent of the number of pixels (equivalent to the so-called Bayer arrangement). Therefore, the imaging device of Embodiment 1 can generate color information with high resolution of a single pixel size, in addition to being highly sensitive.

The arrangement of the micro-optical elements and the pixels that achieve the resolution of the single pixel size as described above is not limited to that shown in FIG. 9(b) and 9(c) show another example, in which the row of the minute spectral element 101 and the color pixel unit U configured along the x-axis direction is one pixel in FIG. 9(b). They are sequentially arranged in the y-axis direction while being shifted in the x-axis direction by the size of two pixels in FIG. 9(c). With such an arrangement as well, color information can be generated with a resolution of a single pixel size, as in FIG. 9(a).

FIGS. 10A to 10C show examples of layouts different from FIGS. 9A to 9C, in which the order of the three pixels D _B , D _G , and D _R is reversed for each row. 9(a) to 9(c) described above with respect to the shift in the x-axis direction. Also in this case, color information can be generated with a resolution of a single pixel size, as in FIG. 9A. In order to reverse the order of the three pixels D _B , D _G , and D _R , a pattern in which the columnar structures 121-1 and 121-2 of the microscopic spectroscopic element 101 are horizontally reversed along the x-axis is used. You can use it.

In the pixel arrangements shown in FIGS. 9A to 9C and FIGS. 10A to 10C described above, the function of each minute spectroscopic element 101 causes the incident light to be the light of the first color component (R). 1 direction (right), the second color component light (G) propagates in the second direction (straight ahead), and the third color component light (B) propagates in the third direction (left). It is assumed that three pixels 102D _R (right), D _G (middle), and D _B (left) immediately below the spectral element 101 correspond to detection of R, G, and B color information, respectively. As described above, depending on the configuration of the minute spectral element 101, which of the three RGB colors the pixel 102 immediately below the minute spectral element 101 corresponds to changes, but basically the order in the color pixel unit U changes. It is only done. Even in such a case, if the arrangement is set according to the arrangement rules of the color pixel units U shown in FIGS. 9 and 10, it is possible to similarly generate color information with a resolution of a single pixel size.

In the above description, the imaging device 100 using only the minute spectroscopic device 101 has been described. Next, a modification in which a subtractive color filter is used together will be described.

FIG. 11 shows a cross-sectional view of a schematic configuration of an imaging device that is a modification of Embodiment 1 of the present invention. The difference from FIG. 3 is that color filters 104 corresponding to the colors of the pixels 102 are arranged above the pixels 102 corresponding to the color components, and the rest is the same. In the case of this configuration, the light utilization efficiency is improved and the color reproducibility is also improved as compared with the conventional configuration of only color filters.

For example, from FIG. 7, it is assumed that the spectral efficiency for RGB of the minute spectral element 101 is 40 to 60%. It is also assumed that the transmittance (spectral efficiency) in the corresponding wavelength range of the RGB color filters 104 is 90%. Suppose the incident light has an intensity ratio of RGB 1:1:1. In this case, in a configuration in which both the minute spectral element 101 and the color filter 104 are used, light passes through both and enters the pixel, so the total amount of light intensity reaching the RGB3 pixel 102 is 36 to 54%. Furthermore, the spectral performance of the minute spectral element 101 and the color filter 104 are multiplied, and the light enters each pixel 102 with unnecessary color components removed, thereby greatly improving color reproducibility. On the other hand, in the case of the configuration with only the color filter 104, the total amount of light intensity reaching the three pixels 102 is 30%, and the color reproducibility is also poor compared to the configuration in which the color filters are used together. Therefore, by using a configuration that uses both the minute spectral element 101 and the color filter 104, the sensitivity is 1.2 to 1.8 times higher than that of a conventional configuration that uses only color filters, while improving color reproducibility. expected to improve. Although the light utilization efficiency is lower than that of the configuration using only the minute spectral element 101, the color reproducibility is greatly improved. It can be said that the structure is well-balanced.

(Embodiment 2)
Next, an imaging device according to Embodiment 2 of the present invention will be described.

FIG. 12(a) is a top view of a schematic configuration of part of an imaging device according to Embodiment 2 of the present invention, and FIG. 12(b) is a cross-sectional view thereof. As shown in FIGS. 12A and 12B, the image pickup device 300 and the image pickup device using the image pickup device 300 of the second embodiment are different from the first embodiment in that a plurality of The difference is that the directions of the structure patterns of the minute spectroscopic element 101 are alternately reversed.

Also, the rows of the minute spectral elements 101 and the color pixel units U configured along the x-axis direction are sequentially arranged in the y-axis direction while being shifted by two pixel sizes in the x-axis direction. Also in the direction, the directions of the structure patterns of the minute spectroscopic element 101 are alternately reversed. Furthermore, among the three pixels 102 adjacent to each other along the x-axis direction that receive the light split by one micro spectroscopic element 101, the two pixels 102 on both outer sides are the other two adjacent micro spectroscopic elements. 101 is different in that it also receives light that has been dispersed. Other components of the second embodiment are the same as those of the first embodiment. In the following, differences from the first embodiment will be mainly described, and descriptions of overlapping points will be omitted.

As shown in FIG. 12(b), since the directions of the structure patterns of the minute spectral element 101 are alternately reversed along the x-axis direction, the combinations of the color components and the polarization directions are alternately reversed. Accordingly, the pixels 102 corresponding to the color components immediately below each minute spectral element 101 are arranged in the order of D _R , D _G , D _B , D _G , D _R , D _G , D _B . . . from the left. ing. A pixel 102D _G is arranged directly below each minute spectroscopic element 101 , and the pixels 102D R or D B on either side of the pixel 102D _R or D _B also receive the light split by the two adjacent minute spectroscopic elements 101 .

White light incident on the imaging element 300 is first condensed by the microlens array, and almost all the light passes through the minute spectroscopic element 101 corresponding to each microlens 103 . Light is spatially separated into three wavelength bands in the xz plane by each micro spectroscopic element 101 and received by three pixels 102 corresponding to each micro spectroscopic element 101 . At this time, the pixels 102 (D _R , D _B ) on both sides of the pixel 102 (D _G ) immediately below the minute spectral element 101 also receive light propagating from the adjacent two minute spectral elements 101, but the structural pattern is reversed. will receive the same wavelength range.

Note that the above is just an example, and depending on the configuration of each minute spectral element 101, the combination of the color component and the propagation direction can be freely changed, and accordingly the pixels 102 corresponding to RGB are also changed. When the light spatially separated into three wavelength ranges is received by each of the three pixels 102, photoelectric conversion is performed by the photoelectric conversion element in each pixel 102, and the light is output as an image signal containing color information.

FIG. 13 schematically shows the arrangement of pixels of an imaging device according to Embodiment 2 of the present invention. One color pixel unit U is four pixels 102 including one D _R , two D _G , and one D _B . In this case, even if the color pixel unit _U1 shown in the figure is shifted by a single pixel in the x-axis direction or the y-axis direction, the color pixel unit U1 includes one D _R , two D _G , and one D _B . A pixel unit _U2 can be constructed. That is, if color information is obtained while shifting the color pixel unit U by single pixels on the xy plane, it is possible to obtain information on three colors of RGB corresponding to the number of pixels. This means that the resolution of the imaging device can be increased to the order of the number of pixels. Therefore, the imaging device 300 of Embodiment 2 can generate color information with a high resolution of a single pixel size, in addition to being highly sensitive.

As described above, even in the configuration of the second embodiment, functions similar to those of the first embodiment can be realized. Further, the second embodiment is the same as the first embodiment except for the difference from the first embodiment, and the common components have the same effects as those described in the first embodiment. can be changed.

(Embodiment 3)
Next, an imaging device according to Embodiment 3 of the present invention will be described.

FIG. 14(a) is a top view of a schematic configuration of part of an imaging device according to Embodiment 3 of the present invention, and FIG. 14(b) is a cross-sectional view thereof. As shown in FIGS. 14A and 14B, the imaging element 400 and the imaging apparatus of Embodiment 3 are arranged such that the microlenses correspond to the pixels one-to-one, compared to Embodiment 1. The difference is that Another difference is that a matrix operation using a photoelectric conversion signal from each pixel 102 is used to acquire color information. Other components are the same as those of the first embodiment. In the following, differences from the first embodiment will be mainly described, and descriptions of overlapping points will be omitted.

As shown in FIG. 14B, the microlenses 103 are arranged in one-to-one correspondence with the pixels 102 . Accordingly, of the white light incident on the imaging device 400, the light incident on each minute spectral element 101 and color-separated is only the light condensed by the microlens 103 positioned directly above the minute spectral element 101. , and the rest of the light is directly incident on the pixel directly below each microlens via each microlens 103 .

Here, assuming that the intensity of white light incident on a single microlens 103 is represented by W, and the intensity of the three colors RGB constituting the white light is represented by R, G, and B, respectively, the three microlenses 103 pass through the pixel 102D. Lights incident on _R 1 , D _G , and D _B are light with intensities represented by W+R, G, and W+B, respectively. Note that the _{above is} just an example, and depending on the configuration of each micro- _splitting element 101, the combination of the color component and the propagation direction can be freely changed. The composition of the color components to be used is also changed. In the following description, acquisition of color information by matrix operation when light having an intensity of W+R, G, and W+ _B is incident on the pixels 102D _R , D _G , and D B , respectively, will be described. It goes without saying that the numerical values of the matrix operators can be changed in various ways.

The lights of W+R, G, and W+B intensities that have entered the respective pixels 102 are photoelectrically converted by photoelectric conversion elements and output as photoelectric conversion signals. Let S _R , S _G , S _B , and S _W be the photoelectric conversion signals corresponding to the three colors of RGB and the light intensity of the white light W, and output by each pixel 102 on which light of W+R, G, and W+B intensities is incident. Let S _W+R , S _G , and S _W+B be photoelectric conversion signals. S _W is represented by S _W =S _R +S _G +S _B , and S _W+R and S _W+B are S _W+R =S _W +S _R and S _W+B =S _W +S _B respectively. It can be represented by a relational expression. In addition, since the light incident on the pixel 102D _G is the G component separated by the minute spectroscopic element 101, S _G is output as it is.

From the above, S _R , S _G , and S _B can be obtained by matrix operations using the following S _W+R , S _G , and S _W+B .

_{Therefore , three} color component _{intensity information S R} , S _G , and S _B can be determined.

As described above, even in the configuration of the third embodiment, functions similar to those of the first embodiment can be realized. The third embodiment is the same as the first embodiment except for the differences from the first embodiment, and the common components have the same effects as those described in the first embodiment, and the same modifications are made. is possible. In addition, in a modification using a combination of color filters, it is desirable to dispose color filters of corresponding color components only on the pixels 102 immediately below the minute spectral element 101 .

(Embodiment 4)
Next, an imaging device according to Embodiment 4 of the present invention will be described.

FIG. 15(a) is a top view of a schematic configuration of part of an imaging device according to Embodiment 4 of the present invention, and FIG. 15(b) is a cross-sectional view thereof. As shown in FIGS. 15A and 15B, the imaging element 500 of Embodiment 4 and the imaging apparatus using it are different from Embodiment 2 in that the microlenses 103 correspond to the pixels 102 one-to-one. They are different in that they are arranged correspondingly. Another difference is that a matrix operation using a photoelectric conversion signal from each pixel 102 is used to obtain color information. Other components are the same as those of the second embodiment. In the following, differences from the second embodiment will be mainly described, and descriptions of overlapping points will be omitted.

As shown in FIG. 15B, the microlenses 103 are arranged in one-to-one correspondence with the pixels 102 . Accordingly, of the white light incident on the imaging device 500, the light incident on each minute spectroscopic element 101 and color-separated is only the light condensed by the microlens 103 positioned directly above the minute spectroscopic element 101. , and other light is directly incident on the pixel 102 directly below each microlens 103 via each microlens 103 .

Here, as in the description of the third embodiment, let W be the intensity of white light incident on a single microlens 103, and let R, G, and B be the intensities of the three colors RGB forming the white light. Light incident on the pixels 102D _R , D _G , and D _B through the three microlenses 103 is light of intensity represented by W+2R, G, and W+2B, respectively. Note that the _{above is} just an example, and depending on the configuration of each micro- _splitting element 101, the combination of the color component and the propagation direction can be freely changed. The composition of the color components to be used is also changed. In the following description, acquisition of color information by matrix operation when light with an intensity of W+2R, G, and W+2B is incident on the pixels 102D _R , D _G , and D _B , respectively, will be described. It goes without saying that the numerical values of the matrix operators can be changed in various ways.

The lights of W+2R, G, and W+2B intensities that have entered the respective pixels 102 are photoelectrically converted by photoelectric conversion elements and output as photoelectric conversion signals. Here, as in the description of the third embodiment, the photoelectric conversion signals corresponding to the three colors of RGB and the light intensity of the white light W are S _R , S _G , S _B , and S _W , and the light of intensities of W+2R, G, and W+2B. Let S _W+2R , S _G , and S _W+2B be the photoelectric conversion signals output by the pixels 102 on which the incident light is incident. S _W is represented by S _W =S _R +S _G +S _B , and S _W+2R and S _W+2B are S _W+2R =S _W +2S _R and S _W+2B =S _W +2S _B , respectively. It can be represented by a relational expression. In addition, since the light incident on the pixel 102D _G is the G component separated by the minute spectroscopic element 101, S _G is output as it is.

From the above, S _R , S _G , and S _B can be obtained by matrix operations using the following S _W+2R , S _G , and S _W+2B .

_{Therefore , the intensity information of} the three color components S _R , S _G , and S _B can be determined.

As described above, even in the configuration of the fourth embodiment, functions similar to those of the second embodiment can be realized. The fourth embodiment is the same as the second embodiment except for the differences from the second embodiment, and the common components have the same effects as those described in the second embodiment, and the same modifications are made. is possible. In addition, in a modification using a combination of color filters, it is desirable to dispose color filters of corresponding color components only on pixels immediately below the minute spectral element 101 .

The first to fourth embodiments described above are merely preferred specific examples of the present invention, and the present invention is not limited to these, and various modifications are possible.

In Embodiments 1 to 4 described above, an example has been shown in which SiN is assumed as the material of the microscopic spectroscopic element 101, but the present invention is not limited to this. For example, when the image pickup device of the present invention is used in the visible light region with a light wavelength of 380 to 800 nm, materials such as SiN, SiC, TiO ₂ and GaN can be used as the material of the microspectroscopic device. It is suitable because it is high and has low absorption loss. Materials such as Si, SiC, SiN, TiO ₂ , GaAs, and GaN are suitable for near-infrared light with a wavelength in the range of 800 to 1000 nm as low-loss materials for these lights. . In addition to the above materials, InP or the like can be used in the long-wavelength near-infrared region (communication wavelengths of 1.3 μm, 1.55 μm, etc.). Furthermore, when forming a microscopic spectroscopic element by pasting and coating, polyimide such as fluorinated polyimide, BCB (benzocyclobutene), photocurable resin, UV epoxy resin, acrylic resin such as PMMA, and polymer such as general resist etc. are mentioned as materials.

Similarly, in Embodiments 1 to 4 described above, SiO ₂ is assumed as the material of the transparent layer 111, but the present invention is not limited to this. General glass materials, SiO ₂ , air layers, etc. may be used as long as the refractive index is lower than the refractive index of the microscopic element material and the loss is low with respect to the wavelength of the incident light.

In the above-described Embodiments 1 to 4, the light in the three wavelength regions corresponding to the microscopic spectroscopic element 101 is the light in the three primary colors of red, green, and blue. One of them may be light of a wavelength other than the three primary colors (for example, infrared light or ultraviolet light).

Although the present invention has been described above based on specific embodiments, it goes without saying that the present invention is not limited to the above embodiments and can be variously modified without departing from the scope of the invention.

1 object 10 imaging device 11 lens optical system 12 imaging element 13 signal processing unit 100, 200, 300, 400, 500, 600, 610, 620 imaging element 101 microscopic spectroscopic element 102 pixel 103 microlens 104 color filter 111 transparent layer 112 wiring Layer 121 Columnar structure 601 Wiring layer 602 Pixel 603 Transparent layer 604 Color filter 605 Microlens 606, 607 Fine structure

Claims (4)

a pixel array in which a plurality of pixels including photoelectric conversion elements are arranged on a substrate;
a transparent layer formed on the pixel array;
a spectroscopic element array in which a plurality of spectroscopic elements are arranged inside or on the transparent layer;
Each of the spectroscopy elements includes a set of microstructures composed of a plurality of microstructures made of a material having a refractive index higher than that of the transparent layer, and the set of microstructures comprises: The spectroscopic element comprises a plurality of fine structures having different shapes in the horizontal direction with respect to the pixel array, having a bottom surface and a top surface of the structure that are rotationally symmetrical about the center as an axis of symmetry, and arranged at regular intervals. at least part of the light incident on is separated into first to third polarized light beams having different propagation directions depending on the wavelength, emitted from the spectroscopic element, and continuously arranged in one direction of the pixel array An image pickup device characterized in that light is incident on each of the three pixels. a pixel array in which a plurality of pixels including photoelectric conversion elements are arranged on a substrate;
a transparent layer formed on the pixel array;
a spectroscopic element array in which a plurality of spectroscopic elements are arranged inside or on the transparent layer;
Each of the spectroscopy elements includes a set of microstructures composed of a plurality of microstructures, and the set of microstructures has a different shape in the horizontal direction with respect to the pixel array. wherein the pixel array is arranged at a position where it receives the light dispersed in the direction corresponding to the wavelength by the plurality of spectroscopic elements,
An imaging device, wherein a part of the shape of each of the plurality of microstructures in the set of microstructures is different from a part of the shape of the arranged microstructures. 3. The imaging device according to claim 2, wherein the microstructure has a bottom surface and a top surface that are rotationally symmetrical about a center. An imaging device according to claim 1 or 2;
an imaging optical system for forming an optical image on the imaging surface of the imaging device;
a signal processing unit that processes an electrical signal output by the imaging device;
An imaging device comprising:

Images