JP2015169688A - Compound-eye imaging optical system and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compound-eye imaging optical system capable of suppressing a ghost and achieving reduction in the thickness of an imaging apparatus while obtaining a high-quality image, and an imaging apparatus including the same.SOLUTION: A compound-eye imaging optical system includes a facet optical system whose optical surface closest to an image side: has a peripheral part, on the outside of at least 70% of an effective diameter, having a convex shape to an object side; and satisfies the following conditional expression: νd>40 (1) where νd represents an Abbe number at a d line of a material with which the optical surface, of the facet optical system, closest to the image side is formed.

Description

  The present invention is small and thin, and uses a plurality of array lenses in which a plurality of lenses are formed on a solid-state imaging device such as a CCD (Charge Coupled Device) type image sensor or a CMOS (Complementary Metal Oxide Semiconductor) type image sensor. The present invention relates to a compound eye imaging optical system and an imaging apparatus for forming an object image.

  In recent years, in mobile terminals such as smartphones, in order to improve design, downsizing of imaging devices mounted on them has been promoted, and accordingly, there has been an increasing demand for lowering the height of optical systems mounted on imaging devices. Yes. On the other hand, even if it is a portable terminal, it is not allowed that the captured image has a low image quality, so that high performance of the optical system is also required in order to realize a high image quality.

  In response to these requirements, a plurality of object images are formed on the imaging surface of a solid-state image sensor using an array lens composed of a plurality of imaging optical systems (single-eye optical systems) arranged with different optical axes. Thus, a small and thin imaging apparatus using a so-called super-resolution technique for reconstructing one image by performing image processing on an image signal corresponding to each object image has been developed. In a compound-eye imaging optical system used in such an imaging apparatus, a high-pixel image is created from a low-pixel image by reconstructing one image from a plurality of images formed by each of a plurality of single-eye optical systems. Therefore, the number of pixels in the image area corresponding to each individual optical system can be reduced, and the individual optical system can be configured with a small number of lenses. As a result, it is possible to provide a high-resolution imaging device while realizing a significantly lower profile than existing optical systems.

  By the way, in the case of forming a plurality of optical images using an array lens, there is a problem that a rainbow ghost is generated. Such a problem will be described with reference to FIG. FIG. 1 is a cross-sectional view of a compound-eye imaging optical system in which a first array lens AL1 having a plurality of single-eye lenses L1 and a second array lens AL2 having a plurality of single-eye lenses L2 are stacked. In a compound-eye imaging optical system having a relatively small number of sheets, it is preferable to make the optical surface closest to the image side convex in order to make the incident angle characteristics (CRA) and distortion performance to the imaging surface appropriate. In this case, as shown in the center of FIG. 1, the light beam LB from the subject incident on the single lens L2 of the second array lens AL2 is incident on the image side surface S4 of the single lens L2 on the optical axis as shown by the arrow. Is refracted so as to be closer, and enters the IR cut filter F.

  Here, most of the light beam LB incident on the IR cut filter F is transmitted through the IR cut filter F and incident on the imaging surface I of the solid-state image sensor, but the light beam reflected by the IR cut filter F is an individual lens. The light enters the second array lens AL2 again from the image side surface S4 of L2, is reflected by the object side flange surface FL2 of the second array lens AL2, is refracted again by the image side surface S4 of the single lens L2, and is applied to the IR cut filter F. Incident light is transmitted through the image pickup surface I and is recognized as a ghost. Since this ghost is refracted twice by the image side surface S4 of the single lens L2, the chromatic aberration is amplified, and a slight shift occurs in the position where the ghost is generated according to the wavelength. When a plurality of images in which such a ghost is generated is synthesized, there is a problem that a synthesized image in which an unsightly iridescent ghost is conspicuous is obtained.

  On the other hand, as a general method for suppressing ghost, there is a case where a light-shielding stop is disposed outside the effective diameter. However, even if a light blocking diaphragm is disposed between the image side surface S4 and the IR cut filter F, the light beam LB reflected by the IR cut filter F repeats incidence and emission within the effective diameter of the image side surface S4. Is not effective in suppressing the ghost.

JP 2012-203119 A

  In Patent Document 1, a ghost is reduced by giving a predetermined relationship among a distance between two lenses, a back focus of an image-side lens, and a refractive index of an object-side lens in a two-lens configuration lens. Technology is disclosed. However, the technique of Patent Document 1 suppresses a ghost caused by a light beam reflected by the image side surface of the object side lens, and does not suppress a ghost generated by refraction of the image side surface of the image side lens twice. Have difficulty.

  The present invention has been made in view of the problems of the prior art, and is a compound-eye imaging optical system that can realize a thin imaging apparatus while suppressing ghost and acquiring a high-quality image, and uses the same. An object of the present invention is to provide an image pickup apparatus.

The compound eye imaging optical system according to claim 1 is a compound eye imaging optical system that forms a plurality of object images on an imaging surface of a solid-state imaging device.
The compound-eye imaging optical system has at least two or more array lenses in which a plurality of single-eye lenses are integrally formed, and a plurality of single-eye optical systems are formed by stacking the array lenses in the optical axis direction. And
The optical surface closest to the image side of the single-eye optical system is characterized in that at least a peripheral portion outside 70% of the effective diameter is convex toward the object side and satisfies the following conditional expression.
νd> 40 (1)
However,
νd: Abbe number at the d-line of the material forming the optical surface closest to the image side of the single-eye optical system

According to the present invention, at least a peripheral portion outside 70% of the effective diameter is convex toward the object side, and a single lens that forms the optical surface closest to the image is formed using a material that satisfies the expression (1). By doing so, it is possible to suppress the occurrence of a shift in the ghost generation position according to the wavelength, and the rainbow-colored ghost can be made inconspicuous in the synthesized image. Further, since the ghost can be suppressed from being conspicuous by selecting the material of the single lens, the influence on the shape of the single lens is small, and the degree of freedom of design is increased. It is more preferable that the following conditional expression (1) ′ is satisfied.
νd> 55 (1) ′

A compound eye imaging optical system according to a second aspect is the invention according to the first aspect, wherein the maximum surface angle in a peripheral portion outside 70% of the effective diameter of the optical surface on the most image side is θ, and the most image is obtained. If the maximum tilt angle of the principal ray emitted from the optical surface on the side and incident on the imaging surface is defined as CRA, the following conditional expression is satisfied.
0.4 <θ / CRA <2.0 (2)

Referring to FIG. 1, the maximum surface angle in the peripheral portion outside 70% of the effective diameter of the optical surface S4 closest to the image side is θ, and the main surface that exits from the optical surface S4 closest to the image side and enters the imaging surface I. Let CRA be the maximum tilt angle of the light beam. Here, when the value of the expression (2) exceeds the lower limit, the maximum surface angle θ does not become too small, and appropriate power can be obtained. On the other hand, when the value of the expression (2) is below the upper limit, the maximum surface angle θ does not become too large, and ghosting can be suppressed. It is more preferable that the following conditional expression (2) ′ is satisfied.
0.6 <θ / CRA <1.5 (2) ′

The compound-eye imaging optical system according to claim 3 is the optical axis between the optical surface on the most image side and a flat plate arranged on the image side of the optical surface on the most image side in the invention according to claim 1 or 2. When the upper distance is A and the core thickness of the single lens of the array lens including the optical surface closest to the image is B, the following conditional expression is satisfied.
0.1 <A / B <0.6 (3)

Referring to FIG. 1, the distance on the optical axis between the optical surface S4 closest to the image side and the IR cut filter F, which is a flat plate disposed on the image side of the optical surface, is A, and the optical surface S4 closest to the image side is The core thickness of the single lens L2 of the included array lens AL2 is B. Here, when the value of the expression (3) exceeds the lower limit, the distance A does not become too small, interference between members can be prevented at the time of assembly, and scratches on the member can be prevented. On the other hand, when the value of the expression (3) is below the upper limit, the distance A does not become too large, and the occurrence of ghost can be suppressed. In FIG. 1, the flat plate is described as an IR cut filter, but the same applies to a color filter. It is more preferable that the following conditional expression (3) ′ is satisfied.
0.2 <A / B <0.55 (3) ′

  The compound-eye imaging optical system according to a fourth aspect is the invention according to any one of the first to third aspects, wherein each of the single-eye optical systems is any one of at least three wavelength bands having different peak wavelengths. An image corresponding to one wavelength band is formed, and the focal lengths of the single-eye optical systems corresponding to the respective wavelength bands are set to be substantially equal.

  FIG. 2 is a schematic diagram illustrating an example of a compound-eye imaging optical system using nine single-eye optical systems IL. A color filter CF is inserted between the single-eye optical system IL and the imaging surface I of the imaging device. The color filter CF includes a green filter CFg, a red filter CFr, and a blue filter CFb.

  Of the subject light that has passed through the single-eye optical system IL, subject light that has entered the green filter CFg is imaged on the single-eye region Ig of the imaging surface I by cutting off subject light having a wavelength other than green. Of the subject light that has passed through the single-eye optical system IL, the subject light that has entered the red filter CFr is imaged on the single-eye region Ir on the imaging surface I by cutting off subject light having a wavelength other than red. . Further, the subject light that has entered the blue filter CFb among the subject light that has passed through the single-eye optical system IL is imaged on the single-eye region Ib of the imaging surface I by cutting the subject light having a wavelength other than blue. Thereafter, the output signals from the individual eye regions are combined (reconstructed) by image processing to form a reconstructed image. Thereby, a high-quality image can be formed by a thin compound eye imaging optical system composed of two array lenses.

  In this way, the wavelength band is divided into a plurality of parts, and the individual eye optical systems are assigned to the respective wavelength bands (red, green, and blue), thereby reducing the burden on each individual lens. Will improve. Note that “the focal lengths are substantially equal” means that when the average value of the focal lengths of all the single-eye optical systems is taken, the focal length of each individual optical system is included within ± 5% of the average value. That means. In FIG. 2, the case where three color filters are used has been described. However, each individual optical system may be assigned to four colors (red, yellow, green, and blue).

  An imaging apparatus according to claim 5 is formed by the compound eye imaging optical system according to any one of claims 1 to 4, an optical filter disposed on an image side of the compound eye imaging optical system, and the compound eye imaging optical system. And a solid-state imaging device that photoelectrically converts the plurality of object images.

  According to the present invention, it is possible to provide a compound-eye imaging optical system capable of realizing a thin imaging apparatus while suppressing ghosts and acquiring an image with high image quality, and an imaging apparatus using the same.

It is sectional drawing of the compound-eye imaging optical system used in order to demonstrate this invention. It is the schematic of a compound eye imaging optical system using a single-eye lens and a color filter. It is a figure which shows typically the imaging device concerning this Embodiment. It is sectional drawing of a compound eye imaging optical system. 2 is a cross-sectional view of a set of single-lens lenses (single-eye optical system) stacked in the optical axis direction in the compound-eye imaging system of Example 1. FIG. FIG. 4 is an aberration diagram of Example 1 (spherical aberration (a), astigmatism (b), distortion (c)). 6 is a cross-sectional view of a set of single-lens lenses (single-eye optical system) stacked in the optical axis direction in the compound-eye imaging system of Example 2. FIG. FIG. 6 is an aberration diagram of Example 2 (spherical aberration (a), astigmatism (b), distortion (c)). 6 is a cross-sectional view of a set of single-lens lenses (single-eye optical system) stacked in the optical axis direction in the compound-eye imaging system of Example 3. FIG. FIG. 6 is an aberration diagram of Example 3 (spherical aberration (a), astigmatism (b), distortion (c)). FIG. 6 is a cross-sectional view of a set of single-lens lenses (single-eye optical system) stacked in the optical axis direction in the compound-eye imaging system of Example 4. FIG. 6 is an aberration diagram of Example 4 (spherical aberration (a), astigmatism (b), distortion (c)).

  Hereinafter, a compound eye imaging system according to the present invention and an imaging apparatus using the same will be described. A compound-eye optical system is an optical system in which a plurality of lens systems (single-eye optical systems) are arranged in an array. Each lens system captures the same field of view, and each lens system has a different field of view. It is usually divided into a field division type that performs imaging. The compound eye optical system according to the present invention can be used for any type, but here, from a plurality of images obtained by a plurality of lens systems that are directed in substantially the same direction and have a minute parallax, than individual images. A super-resolution type used for super-resolution processing for outputting one composite image (reconstructed image) having a higher resolution will be described.

  FIG. 3 schematically shows the imaging apparatus according to the present embodiment. As illustrated in FIG. 3, the imaging device DU includes an imaging unit LU, an image processing unit 1, a calculation unit 2, a memory 3, and the like. The imaging unit LU includes one imaging element SR and a compound-eye imaging optical system LH that forms a plurality of images having minute parallax with respect to the imaging element SR. As the image sensor SR, for example, a solid-state image sensor such as a CCD image sensor or a CMOS image sensor having a plurality of pixels is used. Since the compound-eye imaging optical system LH is provided on the light-receiving surface I that is the photoelectric conversion unit of the imaging element SR so that an optical image of the subject is formed, the optical image formed by the compound-eye imaging optical system LH is Then, it is converted into an electrical signal by the image sensor SR. In the image composition unit in the image processing unit 1, one image data (single-eye composition image ML) having a higher resolution from a plurality of images based on electrical signals corresponding to a plurality of images sent from the image sensor SR. The image processing is executed so as to reconstruct.

  FIG. 4 is an enlarged cross-sectional view of the compound-eye imaging optical system LH. The compound-eye imaging optical system LH includes an aperture stop S, a first array lens AL1, and a second array lens AL2 in order from the object side, and is held by a lens frame HLD. The first array lens AL1 includes a single lens L1 in which the first object side surface S1 is formed on the object side and the first image side surface S2 is formed on the image side, arranged in 3 rows and 3 columns.

  Further, the second array lens AL2 is formed by arranging the single lens L2 in which the second object side surface S3 is formed on the object side and the second image side surface S4 is formed on the image side, arranged in 3 rows and 3 columns. The first-eye lens L1 and the second eye-lens L2 that are laminated with the optical axes aligned constitute a single-eye optical system.

  The number of single-lens lenses is made equal to the number of object images (referred to as single-eye images) formed on the imaging surface I of the image sensor SR. That is, the light beams that have passed through the single-lens L1 and L2 stacked in the optical axis direction form one image on the imaging surface I. S is an aperture stop formed around the side surface of the first object, F is a parallel plate assuming a color filter or an IR cut filter, and CG is a parallel plate assuming a seal glass of a solid-state imaging device. . I is an imaging surface I of the solid-state imaging element SR mounted on the substrate ST.

  At least one of the first array lens AL1 and the second array lens AL2 may be integrally molded. In addition to the first array lens AL1 and the second array lens AL2, a third array lens may be laminated. Further, each of the single-eye optical systems may be configured to be optimally designed for three or more different wavelength bands having different peak wavelengths and combined with a color filter that transmits a suitable wavelength band (see FIG. 2). ). Also at this time, it is preferable that the individual eye optical systems have substantially equal focal lengths.

  As shown in FIG. 3, the image processing unit 1 responds to a plurality of single-eye images Zn (n = 1, 2, 3,...) Formed on the imaging surface I of the imaging element SR by the compound-eye imaging optical system LH. These signals can be combined to output one reconstructed image ML. The reconstructed image ML is compressed by the calculation unit 2 and stored in the memory 3.

Next, examples suitable for the above-described embodiment will be described. In the following embodiments, the compound eye imaging optical system is common, so its specifications are described.
Fno: F number ω: Angle of view (°)
Y: Image height (mm)
r: radius of curvature (mm)
d: Shaft upper surface distance (mm)
nd: refractive index of lens material with respect to d-line νd: Abbe number with respect to d-line of lens material

  In each embodiment, S is a surface number, and the surface on which the aspheric coefficient is described is a surface having an aspheric shape. The aspheric shape has an apex at the surface as an origin and an X axis in the optical axis direction. The height in the direction perpendicular to the optical axis is represented by the following “Equation 1”.

However,
Ai: i-order aspheric coefficient R: radius of curvature K: conic constant

Example 1
Table 1 shows lens data of Example 1. In the following (including the lens data in the table), a power of 10 (for example, 2.5 × 10 ⁻⁰² ) is expressed using E (for example, 2.5E-02). FIG. 5 is a cross-sectional view of the single-eye imaging optical system of Example 1, but the flange portion is omitted (the same applies hereinafter). In the single-lens imaging optical system of Example 1, the aperture stop S, the first single-lens L1, and the peripheral portion outside at least 70% of the effective diameter of the optical surface closest to the image are convex in order from the object side. And a second single-lens lens L2 having a shape. I denotes an imaging surface, F denotes a color filter or IR cut filter, and CG denotes a parallel plate assuming a sealing glass of a solid-state imaging device. FIG. 6 is an aberration diagram of Example 1 (spherical aberration (a), astigmatism (b), distortion (c)). Here, in the spherical aberration diagram of FIG. 6, the solid line represents the amount of spherical aberration with respect to the d line, and the dotted line represents the amount of spherical aberration with respect to the g line. In the astigmatism diagrams, the solid line represents the sagittal direction and the dotted line represents the meridional direction (the same applies hereinafter).

[Table 1]
Example 1
Unit mm

[1a] Optical system data
srd nd νd
1 infinity -0.087 aperture
2 0.6246 0.570 1.5447 56.20
3 1.1431 0.299
4 -4.9482 0.631 1.5447 56.20
5 infinity 0.069
6 infinity 0.175 1.5231 54.50
7 infinity 0.100
8 infinity 0.400 1.5231 62.20
9 infinity 0.107
10 infinity

[1b] Specification value
Focal length 2.02 ω (degrees) 28.28
Fno 3.1 total lens length 2.35

[1c] Aspheric coefficient Ai and conic constant K of aspheric lens
S: 2/3/4/5
K: -2.2276E + 00 / 2.2157E + 00 / 0.0000E + 00 / 0.0000E + 00
A3: 1.5247E-01 / 5.0669E-01 / -1.0764E-01 / 0.0000E + 00
A4: 1.8162E-01 / -3.5626E + 00 / -6.1228E-01 / -1.4880E-01
A5: -7.3169E + 00 / 0.0000E + 00 / 0.0000E + 00 / 0.0000E + 00
A6: 8.2956E + 01 / 1.1034E + 02 / 1.0049E + 00 / -1.0830E + 00
A8: -1.4945E + 03 / -2.4613E + 03 / -1.0531E + 02 / 4.4651E + 00
A10: 1.7928E + 04 / 3.6272E + 04 / 1.2073E + 03 / -1.5922E + 01
A12: -1.1185E + 05 / -3.1555E + 05 / -6.1147E + 03 / 3.4994E + 01
A14: 2.7848E + 05 / 1.4841E + 06 / 9.5787E + 03 / -4.2273E + 01
A16: 0.0000E + 00 / -2.8602E + 06 / 8.8057E + 03 / 2.0762E + 01

(Example 2)
Table 2 shows lens data of Example 2. FIG. 7 is a cross-sectional view of the single-eye imaging optical system of Example 2. The single-lens imaging optical system of Example 2 has at least the effective diameter of the first single-lens L1, the aperture stop S, the second single-lens L2, and the optical surface closest to the image side in order from the object side. The peripheral part outside 70% is composed of a third individual lens L3 having a convex shape. I indicates an imaging surface, and F indicates a parallel plate assuming a color filter, an IR cut filter, and the like. FIG. 8 is an aberration diagram of Example 2 (spherical aberration (a), astigmatism (b), distortion (c)).

[Table 2]
Example 2
Unit mm

[2a] Optical system data
srd nd νd
1 1.2072 0.682 1.5447 56.20
2 -36.3751 0.055
3 infinity 0.029 aperture
4 infinity 0.253
5 -0.8715 0.706 1.5447 56.20
6 -0.5669 0.128
7 infinity 0.459 1.5447 56.20
8 0.8918 0.242
9 infinity 0.175 1.5231 54.50
10 infinity 0.392
11 Image plane

[2b] Specification value
Focal length 2.23 ω (degrees) 33.09
Fno 2.9 Total lens length 3.12

[2c] Aspheric coefficient Ai and conic constant K of aspheric lens
S: 1/2/5/6 /
K: -3.5860E-01 / 1.0000E + 01 / -2.3767E + 00 / -2.7241E + 00 /
A3: -5.9539E-03 / 1.8310E-02 / -7.1296E-02 / 1.8030E-02 /
A4: 6.4340E-02 / -3.9251E-01 / -1.0174E-01 / -8.3993E-01 /
A5: -2.0246E-01 / 6.4665E-01 / -3.5057E + 00 / 6.8487E-01 /
A6: 1.3830E-01 / -7.1647E-01 / 3.7017E + 00 / -2.7585E-01 /
A8: 7.0351E-02 / -1.3965E + 01 / 5.3269E + 00 / -9.9653E-02 /
A10: -8.0114E-01 / 1.3864E + 02 / -1.3174E + 01 / 2.3222E + 00 /
A12: 1.6073E-01 / -6.3851E + 02 / -1.1609E + 02 / -6.9659E-01 /
A14: 0.0000E + 00 / 1.4795E + 03 / 3.8694E + 02 / -1.5396E + 00 /
A16: 0.0000E + 00 / -1.3061E + 03 / 0.0000E + 00 / 0.0000E + 00 /

S: 7/8
K: 0.0000E + 00 / -9.0167E + 00
A3: 1.3930E-01 / 8.5325E-02
A4: -1.4020E + 00 / -4.0137E-01
A5: 4.3534E + 00 / 1.9321E-01
A6: -6.3791E + 00 / 2.2411E-03
A8: 8.2561E + 00 / 9.5692E-03
A10: -9.9870E + 00 / -2.8095E-02
A12: 7.7551E + 00 / 1.9484E-02
A14: -3.4653E + 00 / -5.7062E-03
A16: 6.8333E-01 / 0.0000E + 00

(Example 3)
Table 3 shows lens data of Example 3. FIG. 9 is a cross-sectional view of the single-eye imaging optical system of Example 3. The single-lens imaging optical system according to the third exemplary embodiment has, in order from the object side, the aperture stop S, the first single-lens L1, the second single-lens L2, and at least the effective diameter of the optical surface closest to the image side. The peripheral part outside 70% is composed of a third individual lens L3 having a convex shape. I denotes an imaging surface, F denotes a color filter or IR cut filter, and CG denotes a parallel plate assuming a sealing glass of a solid-state imaging device. FIG. 10 is an aberration diagram of Example 3 (spherical aberration (a), astigmatism (b), distortion (c)).

[Table 3]
Example 3
Unit mm

[3a] Optical system data
srd nd νd
1 infinity -0.047 aperture
2 0.9956 0.518 1.5448 56.00
3 22.9678 0.246
4 -0.9564 0.495 1.5448 56.00
5 -0.7197 0.063
6 4.1927 0.515 1.5448 56.00
7 1.0259 0.238
8 infinity 0.175 1.5231 54.50
9 infinity 0.100
10 infinity 0.400 1.5200 62.40
11 infinity 0.040
12 infinity

[3b] Specification values
Focal length 1.97 Ω (degrees) 30.12
Fno 2.8 lens total length 2.79

[3c] Aspheric coefficient Ai and conic constant K of aspheric lens
S: 2/3/4/5 /
K: -1.2400E + 01 / 0.0000E + 00 / -1.7250E + 00 / -5.6479E + 00 /
A3: -1.3474E-01 / 4.0700E-02 / 0.0000E + 00 / 0.0000E + 00 /
A4: 3.8014E + 00 / -9.9638E-01 / -6.1984E-02 / -7.7414E-01 /
A5: -1.6302E + 01 / 6.9747E + 00 / 0.0000E + 00 / 0.0000E + 00 /
A6: 4.1235E + 01 / -1.9339E + 01 / 2.7206E + 00 / 3.0951E + 00 /
A8: -2.1879E + 02 / 7.3415E + 01 / -4.9938E + 01 / -8.5324E + 00 /
A10: 1.2404E + 03 / -2.5441E + 02 / 4.5323E + 02 / 2.1635E + 01 /
A12: -4.2338E + 03 / 5.1315E + 02 / -1.9887E + 03 / -1.2881E + 00 /
A14: 6.1651E + 03 / -4.9670E + 02 / 4.3342E + 03 / -5.8334E + 01 /
A16: 0.0000E + 00 / 0.0000E + 00 / -4.0330E + 03 / 4.4110E + 01 /

S: 6/7
K: 0.0000E + 00 / -6.4200E-01
A3: 0.0000E + 00 / 6.7364E-01
A4: -1.7027E-01 / -5.1248E + 00
A5: 0.0000E + 00 / 1.1641E + 01
A6: -1.6809E + 00 / -1.2670E + 01
A8: 5.2673E + 00 / 1.0647E + 01
A10: -5.6885E + 00 / -1.0321E + 01
A12: -3.8879E + 00 / 6.8972E + 00
A14: 1.7325E + 01 / -2.6664E + 00
A16: -1.5780E + 01 / 4.3318E-01

Example 4
Table 4 shows lens data of Example 4. FIG. 11 is a cross-sectional view of the single-eye imaging optical system of Example 4. The single-lens imaging optical system of Example 4 has at least the effective diameter of the aperture stop S, the first single-lens L1, the second single-lens L2, and the optical surface closest to the image side in order from the object side. The peripheral part outside 70% is composed of a third individual lens L3 having a convex shape. I indicates an imaging surface, and F indicates a parallel plate assuming a color filter, an IR cut filter, and the like. FIG. 12 is an aberration diagram of Example 4 (spherical aberration (a), astigmatism (b), distortion (c)).

[Table 4]
Example 4
Unit mm

[4a] Optical system data
srd nd νd
1 0.9321 0.58 1.5447 56.20 Aperture
2 -2.8559 0.19
3 -0.5961 0.40 1.6347 23.87
4 -1.6511 0.10
5 0.9130 0.40 1.5447 56.20
6 1.1958 0.16
7 infinity 0.50 1.5073 48.44
8 infinity 0.47
9 infinity 0.00 Image plane

[4b] Specification values
Focal length 2.2
Fno 2.4
ω (degrees) 25.42
Total lens length 2.8

[4c] Aspheric coefficient Ai and conic constant K of aspheric lens
S: 1/2/3/4 /
K: -2.6019E + 00 / 1.0613E + 01 / -4.5445E + 00 / -1.3766E + 01 /
A4: 4.0432E-01 / -6.0283E-03 / -1.0793E + 00 / -9.6655E-01 /
A6: -1.4444E + 00 / -2.1159E + 00 / 7.3918E + 00 / 6.1873E + 00 /
A8: 1.2882E + 01 / 1.1445E + 01 / -5.6858E + 01 / -2.3509E + 01 /
A10: 2.9204E + 01 / -2.2883E + 02 / -3.0446E + 01 / 4.4589E + 01 /
A12: -2.1809E + 03 / 1.7901E + 03 / 3.4003E + 03 / 8.3377E + 01 /
A14: 2.1870E + 04 / 4.1114E + 03 / -1.7635E + 04 / -2.2880E + 02 /
A16: -1.0252E + 05 / -1.4291E + 05 / 3.5512E + 02 / -2.6203E + 03 /
A18: 2.3566E + 05 / 7.6503E + 05 / 2.1154E + 05 / 1.3947E + 04 /
A20: -2.1352E + 05 / -1.3266E + 06 / -4.2605E + 05 / -2.0387E + 04 /

S: 5/6
K: -5.1412E + 00 / 9.2567E-01
A4: -1.4624E + 00 / -8.6004E-01
A6: 4.0069E + 00 / -1.0468E + 00
A8: -2.2850E + 01 / 1.4033E + 00
A10: 7.9337E + 01 / 3.2535E + 01
A12: -1.3320E + 02 / -1.6136E + 02
A14: -1.3360E + 02 / 1.2396E + 02
A16: 7.6351E + 02 / 8.5625E + 02
A18: -2.6748E + 02 / -2.2473E + 03
A20: -9.9549E + 02 / 1.6475E + 03

  Table 5 shows values of the respective examples corresponding to the respective conditional expressions.

DESCRIPTION OF SYMBOLS 1 Image processing part 2 Lens 3 Memory CG Cover glass DU Imaging device F IR cut filter AL1 1st array lens AL2 2nd array lens LH Compound-eye imaging optical system L1-L3 Single-eye lens LU Imaging unit I Imaging surface

Claims (5)

In a compound eye imaging optical system that forms a plurality of object images on the imaging surface of a solid-state imaging device,
The compound-eye imaging optical system has at least two or more array lenses in which a plurality of single-eye lenses are integrally formed, and a plurality of single-eye optical systems are formed by stacking the array lenses in the optical axis direction. And
The compound-eye imaging optical system characterized in that the optical surface closest to the image side of the single-eye optical system has at least a peripheral portion outside 70% of the effective diameter convex toward the object side and satisfies the following conditional expression.
νd> 40 (1)
However,
νd: Abbe number at the d-line of the material forming the optical surface closest to the image side of the single-eye optical system The maximum surface angle in the peripheral portion outside 70% of the effective diameter of the most image-side optical surface is θ, and the maximum tilt angle of the principal ray that is emitted from the most image-side optical surface and incident on the imaging surface is CRA. The compound-eye imaging optical system according to claim 1, wherein the following conditional expression is satisfied.
0.4 <θ / CRA <2.0 (2) A distance on the optical axis between the most image side optical surface and a flat plate disposed on the image side of the most image side optical surface is A, and the single lens of the array lens including the most image side optical surface 3. The compound-eye imaging optical system according to claim 1, wherein when the core thickness is B, the following conditional expression is satisfied.
0.1 <A / B <0.6 (3)     Each of the individual optical systems forms an image corresponding to any one of at least three wavelength bands having different peak wavelengths, and the focal length of the individual optical system corresponding to each wavelength band. The compound-eye imaging optical system according to claim 1, wherein the two are set to be substantially equal to each other.   5. The compound eye imaging optical system according to claim 1, an optical filter disposed on an image side of the compound eye imaging optical system, and a plurality of object images formed by the compound eye imaging optical system are photoelectrically converted. An imaging apparatus comprising a solid-state imaging device.