Image pickup apparatus, optical system, and detection system

Abstract

The invention relates to an image pickup apparatus, an optical system, and a detection system. The image pickup apparatus includes an optical system including a first substrate and a first optical element having a refractive power disposed on the first substrate, and a light receiving element having a light receiving surface on which the optical system forms an image.

Description

Technical Field

[0001] One aspect of the embodiments relates to an image pickup device, an optical system, and a detection system. Background Art

[0002] Conventionally, there has been proposed a compact optical system having high optical performance for use in an image pickup device that performs line of sight (visual line) detection, iris authentication, living body detection, and the like (see US Pat. No. 9,798,115).

[0003] Conventional image pickup devices may cause distortion and partial blur in an image when an object and an optical system are not directly opposite to each other (or when the object plane and a plane orthogonal to the optical axis are not parallel to each other). An image pickup device has also been proposed that detects a line of sight by incorporating a half mirror into an eyepiece optical system so that the object and the optical system are directly opposite to each other, but the half mirror occupies a large space and the size of the image pickup device increases. Summary of the invention

[0004] An image pickup device according to one aspect of the present disclosure includes: an optical system including a first substrate and a first optical element with refractive power disposed on the first substrate; and a light receiving element having a light receiving surface, on which the optical system forms an image. A detection system having the above-mentioned image pickup device also constitutes another aspect of the present disclosure. An optical system according to another aspect of the present disclosure includes a first substrate, a first optical element with refractive power disposed on the first substrate, and an optical element having a plane in contact with air. The following inequality is satisfied:

[0005] 0.5≤θ≤20.0

[0006] Here, θ is the angle [°] of the plane relative to the optical axis in the cross section having the optical axis.

[0007] Further features of various embodiments of the present disclosure will become apparent from the following description of the embodiments with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a cross-sectional view of an optical system according to Example 1.

[0009] Figure 2 : is an aberration diagram of the optical system according to Example 1.

[0010] Figure 3 is a cross-sectional view of an optical system according to Example 2.

[0011] Figure 4 : is an aberration diagram of the optical system according to Example 2.

[0012] Figure 5 is a cross-sectional view of an optical system according to Example 3.

[0013] Figure 6 : is an aberration diagram of the optical system according to Example 3.

[0014] Figure 7 is a cross-sectional view of an optical system according to Example 4.

[0015] Figure 8 : is an aberration diagram of the optical system according to Example 4.

[0016] Fig. 9 is a cross-sectional view of an optical system according to Example 5.

[0017] Fig.10 : is an aberration diagram of the optical system according to Example 5.

[0018] Fig.11 The light receiving surface of the image pickup device according to Example 1 viewed from a direction orthogonal to the optical axis is illustrated.

[0019] Fig.12 The light receiving surface of the image pickup device according to Example 2 viewed from a direction orthogonal to the optical axis is illustrated.

[0020] Fig.13 The light receiving surface of the image pickup device according to Example 3 viewed from a direction orthogonal to the optical axis is illustrated.

[0021] Fig.14 A light receiving surface of the image pickup device according to Example 4 viewed from a direction orthogonal to the optical axis is illustrated.

[0022] Fig.15 The light receiving surface of the image pickup device according to Example 5 viewed from a direction orthogonal to the optical axis is illustrated.

[0023] Fig.16A and 16B is a schematic diagram of an electronic device according to Example 6. DETAILED DESCRIPTION

[0024] Now, the embodiments according to the present disclosure will be described in detail with reference to the accompanying drawings. Corresponding elements in the various drawings will be denoted by the same reference numerals, and their repeated description will be omitted.

[0025] The image pickup apparatus according to each example includes an optical system (imaging optical system) 10 and a light receiving element having a light receiving surface on which the optical system 10 forms an image.

[0026] The optical system IO according to each example is a small optical system obtained using a technology called wafer-level optics. Such an optical system is called a wafer-level lens, and an image pickup device using a wafer-level lens as an imaging optical system is called a wafer-level camera. The optical system IO according to each example is used as an imaging optical system used in a built-in camera of an electronic device such as a mobile phone, a smart phone, a wearable terminal, and a head-mounted display (HMD), or as an objective optical system of an endoscope. The optical system IO according to each example can be used together with a main optical system such as an eyepiece optical system of the above-mentioned electronic device, and can be used in a state where the optical system cannot face the object.

[0027] Figure 1 , Figure 3 , Figure 5 , Figure 7 and Fig. 9 They are cross-sectional views of optical systems (wafer-level lenses / wafer-level optics (WLO)) 10 according to Examples 1 to 5, respectively. In each cross-sectional view, the left side is the object side (front side), and the right side is the image side (rear side).

[0028] OB denotes an object plane. IP denotes an image plane. An imaging surface of an image sensor in an image pickup device, such as a charge coupled device (CCD) sensor or a complementary metal oxide semiconductor (CMOS) sensor, may be disposed on the image plane IP. A photosensitive surface corresponding to a film surface of a film-based camera may be disposed on the image plane IP. However, as long as the light beam enters an effective area of ​​a light receiving element such as an image sensor or a photosensor, the light beam does not need to enter the entire surface of the image plane IP.

[0029] The optical system IO according to each example includes a substrate (first substrate) and an optical element (first optical element) with refractive power disposed on the substrate. The optical system IO according to each example may include a substrate (first substrate) SB1 and a substrate (second substrate) SB2 arranged in sequence from the object side to the image side. In other words, the substrate SB2 may be disposed adjacent to the image side of the substrate SB1. An optical element (second optical element) with positive refractive power may be disposed on the image side of the substrate SB2. A glass substrate GSB for protecting a light receiving surface is disposed between the substrate SB2 and the image plane IP. However, a rear cover glass may be used instead of the glass substrate GSB.

[0030] The glass substrate GSB may be a substrate made by bonding two flat plates together. Thus, it is possible to efficiently manufacture an image pickup device using a method of separately manufacturing an optical system and an imaging unit and bonding the glass flat plates together. The relative positions of the optical system and the imaging unit can be changed, and image pickup devices of various specifications can be easily prepared.

[0031] In each example, each lens is manufactured by a wafer-level process to reduce the size of the optical system 10. That is, they are manufactured by forming a lens layer made of a curable resin material or the like on a wafer that becomes substrates SB1 and SB2. By disposing the substrates manufactured by the wafer-level process at a predetermined distance from the light receiving element, adhering them outside the effective area, and then cutting them, a large number of wafer-level lenses can be manufactured at one time.

[0032] Thermoplastic resin, ultraviolet curing resin, thermosetting resin are used as materials for forming lens layers. Examples include acrylic resin, modified acrylic resin, polycarbonate resin, modified polycarbonate resin (resin containing fluorene skeleton, Iupizeta manufactured by Mitsubishi Gas Chemical Co., Ltd., etc.), silicone resin, cycloolefin polymer, and cycloolefin copolymer, polyvinyl carbazole, polystyrene, polyethylene, Teflon, Teflon AF manufactured by Mitsui Chemours Fluoro Products Co., Ltd., Cytop manufactured by AGC, and perfluoroalkoxy alkane. Blends of these substances, copolymers of some substances, or further blends of copolymers can be used. Materials obtained by adding and / or mixing particles, crystals, etc. of organic low molecular weight or inorganic materials to these resin materials can also be used. Optical elements with refractive index can be easily formed using such resin materials. Glass, quartz, inorganic crystals, transparent ceramics, and engineering plastics can be used as substrate materials according to the optical system 10 of each example. In each example, the substrates SB1 and SB2 are made of glass, but this example is not limited to this embodiment.

[0033] Figure 2 , Figure 4 , Figure 6 , Figure 8 and Fig.10They are respectively aberration diagrams of the optical system IO according to Examples 1 to 5. Each aberration diagram includes a spherical aberration diagram, an astigmatism diagram, a distortion diagram and a lateral aberration diagram. In the spherical aberration diagram, Fno represents the F number. The spherical aberration diagram illustrates the amount of spherical aberration when the wavelength is 850nm or 950nm. In the astigmatism diagram, S represents the amount of astigmatism on the sagittal image plane, and M indicates the amount of astigmatism on the meridional image surface. The distortion diagram illustrates the amount of distortion when the wavelength is 850nm or 950nm. For astigmatism and distortion, the direction horizontal to the optical axis OA, the direction orthogonal to the optical axis OA, and the diagonal direction of the light receiving element are drawn in the order of image height on the light receiving element, and spline interpolation is used between them. In the lateral aberration diagram, the solid line represents the meridional lateral aberration, and the dotted line represents the sagittal lateral aberration. ω is the imaging half angle of view (°). In the case where the optical system IO is composed of a single lens with refractive power, the optical axis OA is defined as the rotation axis. In the case where the optical system 10 includes two or more lenses, the optical axis OA is defined as the direction of the sum of unit vectors in the directions of the rotation axes thereof (each defined as a direction from the object side to the image side).

[0034] Fig.11 , Fig.12 , Fig.13 , Fig.14 and Fig.15 The light receiving surfaces of the image pickup devices according to Examples 1 to 5 observed from a direction orthogonal to the optical axis OA are illustrated respectively. In each example, the optical system 10 is arranged so that the optical axis OA does not coincide with the center C of the light receiving surface. That is, the optical axis OA of the optical system 10 is tilted relative to the optical axis of the main optical system, wherein the optical axis and the center of the light receiving surface coincide with each other on the light receiving surface. On the light receiving surface, the center of the effective area that contributes to imaging and image acquisition does not coincide with the center C of the light receiving surface.

[0035] The characteristic configuration of the optical system 10 according to each example will now be described.

[0036] The optical system 10 according to each example satisfies the following inequality (1):

[0037] 0.2≤s / Rimmax≤1.1 (1)

[0038] Here, s is the distance from the intersection of the optical axis OA and the light receiving surface to the center C of the light receiving surface, and Rimmax is the distance from the farthest position from the center C of the light receiving surface to the center C.

[0039] For example, in the case where the light receiving surface is rectangular or square, the distance Rimmax is the distance from the center C of the light receiving surface to the vertex. The center C of the light receiving surface and the position farthest from the center C of the light receiving surface are considered to be within the effective area that contributes to the imaging of the light receiving surface. The direction from the optical axis OA to the position of the center C of the light receiving surface is not limited, and the direction may be, for example, the long side direction, the short side direction, or the diagonal direction of the light receiving surface.

[0040] In a general coaxial optical system, the optical system and the object cannot face each other directly, for example, trapezoidal distortion and unilateral blur may occur when looking up or down at an oblique direction. Separating the center C of the light receiving surface from the optical axis OA within the range of inequality (1) can cause the center of the imaging range to deviate from the optical axis OA. This construction can provide an image pickup device suitable for line of sight detection of a camera viewfinder or an HMD or liveness detection of a wearable device, wherein the optical system IO cannot face the object directly. For example, since the eyepiece optical system is deployed in a position facing the user's eyes in the eyepiece unit of the camera viewfinder or the HMD, it is difficult to make the camera used for line of sight detection face the object (the user's eyes and the light reflected on the eyes). In such a situation, the optical system IO according to each example can be used.

[0041] When the value becomes lower than the lower limit of inequality (1), the deviation of the imaging range caused by the separation of the center C of the light receiving surface from the optical axis OA is reduced, and in order to obtain high image quality, the optical system IO and the object will be almost directly opposite to each other. When the value becomes higher than the upper limit of inequality (1), the distance between the optical system IO and the light receiving element increases, so that the size of the image pickup device increases, which is not suitable for the strong demand for miniaturization of HMD and wearable devices.

[0042] Generally, when using a CMOS sensor or a CCD sensor, a space is required to arrange wiring and circuits, and the size of the image pickup device may increase. In the image pickup device according to each example, the wiring and circuit of the light receiving element can be arranged on the side opposite to the center C of the light receiving surface using the optical axis OA as a reference. Therefore, the wiring and circuit can be placed in the shadow of the lens, and the size of the image pickup device can be reduced.

[0043] The infinitive (1) can be replaced by the following inequality (1a):

[0044] 0.2≤s / Rimmax≤0.9(1a)

[0045] The infinitive (1) can be replaced by the following inequality (1b):

[0046] 0.25≤s / Rimmax≤0.70(1b)

[0047] The above configuration can realize an image pickup apparatus that is reduced in size and includes an optical system having high optical performance even if the optical system is not facing a subject.

[0048] A configuration that may be satisfied in the optical system 10 according to each example will now be described.

[0049] A lens (first optical element) L12 with negative refractive power can be formed on the image side of substrate SB1, and a lens (second optical element) L2 with positive refractive power can be formed on the image side of substrate SB2. These lenses are formed by wafer-level processes. In this configuration, imaging performance can be ensured within a wide viewing angle, and the incident angle on the light receiving surface can be relaxed. These lenses can be aspherical lenses.

[0050] An aspherical lens (third optical element) L11 having a positive refractive power at the end of the effective area that contributes to imaging can be formed on the object side of the substrate SB1. By deploying an aspherical surface at a position where the on-axis and off-axis light rays are widely spaced, off-axis aberrations can be satisfactorily corrected. The positive refractive power at the end can create a nearly concentric surface for the light passing through the end, and the image quality at the end of the image can be improved. In the optical system IO according to each example, since the optical axis OA does not coincide with the center C of the light receiving element, a wider single-sided viewing angle is required compared to an optical system in which the optical axis and the center of the light receiving element coincide. Therefore, the correction of off-axis aberrations is more important than that of a general optical system.

[0051] The substrate does not necessarily need to be composed of a single substrate and may include two or more substrates. In particular, in the case where the substrate SB1 includes two substrates, optical performance can be improved by forming lenses L11 and L12 on different substrates and pasting the two substrates together.

[0052] In order to protect the lens, a flat plate or a protective plate with substantially the same curvature on both sides may be disposed on the object side. The flat plate or the protective plate may be replaced by a wavelength selective filter, or the wavelength selective filter may be formed on a substrate.

[0053] The configuration in which the lens is formed closest to the object can use a resin material for the lens, so when the lens is used while being exposed to the outside world, surface durability may be a problem. However, in consumer products such as HMDs, a cover member is generally used to ensure the appearance quality, so the problem caused by deploying the lens closest to the object is not necessarily significant.

[0054] An aperture stop (iris) can be formed on the substrate SB2. The aperture stop can be formed on the substrate SB2 by, for example, depositing a light-shielding film such as chrome using a mask and then etching it after deposition. Generally, an aperture stop refers to an aperture whose diameter is variable, but in this specification, it also includes an aperture whose diameter is not variable. The aperture stop may include a thin sheet having an aperture shape. The aperture shape is not limited to a circle, but may be a quadrilateral, a rounded quadrilateral with four sector corners, or the like. It is appropriate to form the aperture stop on the substrate SB (i.e., on a flat surface (plane)) because it can facilitate the control of the mask arrangement in the thickness direction.

[0055] Lenses L12 and L2 may each have a rotationally symmetrical surface. Thus, inspection during manufacturing may be simple. The shape of the outer diameter portion of the lens may be square or rectangular.

[0056] The conditions that can be satisfied by the optical system 10 according to each example will now be described. The optical system 10 according to each example includes an optical element made of glass or resin and disposed in an effective area that contributes to imaging. The optical element has a plane in contact with air and satisfies the following inequality (2). The optical element can be a glass substrate GSB in each example, but can also be other optical elements as long as inequality (2) is satisfied.

[0057] 0.5 ≤ θ ≤ 20.0 (2)

[0058] Wherein θ is the angle [°] of the plane relative to the optical axis OA in the cross section having the optical axis OA. The plane includes the lens surface, two surfaces of the flat plate and their bonding surface.

[0059] Satisfying inequality (2) can tilt the object plane OB. Thus, even if the optical system faces the object obliquely relative to the object instead of facing the optical system IO, the object plane OB can be made to coincide with the object plane. When the value becomes lower than the lower limit of inequality (2), the effect of tilting the object plane OB becomes smaller. When the value becomes higher than the upper limit of inequality (2), the tilt of the object plane OB becomes too large, and manufacturing becomes difficult. In addition, a large space is required to deploy the inclined surface, and the size of the optical system IO increases.

[0060] The optical system 10 according to each example may satisfy one or more of the following inequalities (3) to (10):

[0061] 0.9 ≤ Φ2i / Φ ≤ 1.5 (3)

[0062] 0.0 ≤ |Φ1o / Φ| ≤ 0.4 (4)

[0063] -1.6 ≤ Φ1i / Φ ≤ -0.2 (5)

[0064] -1.9 ≤ Φ1i / Φ2i ≤ -0.1 (6)

[0065] 0.1 ≤ d12 / f ≤ 2.0 (7)

[0066] 35 < ω < 150 (8)

[0067] 0 < f ≤ 10 (9)

[0068] 0.02 ≤ f / id ≤ 1.00 (10)

[0069] Here, Φ is the refractive power of the optical system IO. Φ1o is the refractive power of the lens L11 formed on the object side of the substrate SB1. Φ1i is the refractive power of the lens L12 formed on the image side of the substrate SB1. Φ2i is the refractive power of the lens L2 formed on the image side of the substrate SB2. ω is the angle of view [°] in the direction connecting the center C of the light receiving surface and the optical axis OA. d12 is the distance from the surface on the image side of the lens L12 to the surface on the image side of the substrate SB2 on the optical axis. f is the focal length of the optical system IO. id is the distance from the lens surface of the optical system IO closest to the object to the object to be identified or detected.

[0070] The optical system 10 according to each example has a reverse telephoto type configuration. This configuration can satisfactorily correct aberrations within a wide field of view. This configuration is also effective for widening the angle of a coaxial system. In addition, an optical system 10 in which the optical axis OA is separated from the center C of the light receiving surface is suitable because the single-sided viewing angle across the center C of the light receiving surface on the opposite side of the optical axis OA is larger than that of a coaxial system with the same single-sided viewing angle.

[0071] When the value becomes lower than the lower limit of inequality (3), the incident angle on the light receiving surface becomes larger, and the crosstalk between pixels increases, etc. When the value becomes higher than the upper limit of inequality (3), the positive and negative refractive powers constituting the reverse telephoto lens become too large, and the total length will become too long.

[0072] By definition, the value never becomes lower than the lower limit of inequality (4). In the case where the value becomes higher than the upper limit of inequality (4), the refractive power of lens L11, which is disposed closest to the object and is susceptible to external temperature changes, increases, and changes in image quality and focus position due to temperature changes become significant.

[0073] When the value becomes lower than the lower limit of inequality (5), the angle of incidence on the light receiving surface becomes larger. In addition, the diameter of lens L12 becomes larger. When manufacturing the optical system IO according to each example, the surface distance (interval) is adjusted by inserting a spacer between substrates SB1 and SB2. At this time, since the ineffective area of ​​lens L12 and the ineffective area of ​​the lens formed on the object side of substrate SB2 are wider, the area where the spacer can be placed can be wider, and an accurate surface distance can be maintained. Therefore, the diameter of lens L12 cannot be too large. When the value becomes higher than the upper limit of inequality (5), the positive and negative refractive powers constituting the reverse telephoto lens will become too large, and the entire length becomes too long.

[0074] When the value becomes lower than the lower limit of inequality (6), the positive refractive power constituting the reverse telephoto lens becomes too strong, the incident angle on lens L2 becomes larger, and it becomes difficult to correct off-axis aberrations. When the value becomes higher than the upper limit of inequality (6), the negative refractive power constituting the reverse telephoto lens becomes too strong, the diameter of the effective area of ​​lens L2 becomes larger than the surface of lens L2, and the difficulty of molding lens L2 increases.

[0075] In the case where the value becomes lower than the lower limit of inequality (7), the distance between the lens with positive refractive power and the lens with negative refractive power in the reverse telephoto lens decreases, the state is close to a single lens, and it becomes difficult to correct the aberration within the wide viewing angle range that can be achieved by the reverse telephoto structure. In the case where the value becomes higher than the upper limit of inequality (7), the light diverged by the lens on the substrate SB1 reaches the substrate SB2 after passing through a long optical path length. Therefore, the diameter of the effective area of ​​the lens on the substrate SB2 increases, and the molding difficulty increases.

[0076] In the case where the value becomes lower than the lower limit of inequality (8), the angle of view decreases, and the object often falls outside the frame due to an error in the installation position of the image pickup device or movement or displacement of the object. Such an image pickup device is not suitable for devices such as HMDs and wearable devices. In the case where the value becomes higher than the upper limit of inequality (8), the angle of view becomes too wide, and it becomes difficult to satisfactorily correct off-axis aberrations.

[0077] Since the optical system 10 according to each example is created using a wafer-level process, satisfying inequality (9) can increase the number of processes per wafer and manufacture many optical systems 10 at a time. Since the optical system 10 according to each example is an imaging lens for primary imaging and has a positive refractive power, the value does not become lower than the lower limit of inequality (9). In the case where the value becomes higher than the upper limit of inequality (9), the size of the optical system 10 increases.

[0078] When the value becomes lower than the lower limit of inequality (10), the image magnification decreases, and the effect of shifting the image plane or introducing an inclined surface into the optical system 10 decreases. When the value becomes higher than the upper limit of inequality (10), the distance to the object becomes very short, and it becomes difficult to illuminate the object. In the case where the object is blurred or shifted, the image moves noticeably, and it becomes difficult to image the desired area.

[0079] Inequalities (2) to (10) can be replaced by the following inequalities (2a) to (10a):

[0080] 0.5≤θ≤18.0(2a)

[0081] 0.9≤Φ2i / Φ≤1.4(3a)

[0082] 0.00≤|Φ1o / Φ|≤0.32(4a)

[0083] -1.55≤Φ1i / Φ≤-0.25(5a)

[0084] -1.70≤Φ1i / Φ2i≤-0.15(6a)

[0085] 0.2≤d12 / f≤1.4(7a)

[0086] 35<ω<100(8a)

[0087] 0 <f≤7(9a)

[0088] 0.025≤f / id≤0.095(10a)

[0089] Inequalities (2) to (10) can be replaced by the following inequalities (2b) to (10b):

[0090] 0.5≤θ≤13.0(2b)

[0091] 0.93≤Φ2i / Φ≤1.35(3b)

[0092] 0.00≤|Φ1o / Φ|≤0.25(4b)

[0093] -1.5≤Φ1i / Φ≤-0.3(5b)

[0094] -1.5≤Φ1i / Φ2i≤-0.2(6b)

[0095] 0.3≤d12 / f≤1.1(7b)

[0096] 35<ω<70(8b)

[0097] 0 <f≤3(9b)

[0098] 0.035≤f / id≤0.085(10b)

[0099] The optical system 10 according to each example will be described in detail.

[0100] Example 1

[0101] like Figure 1 As shown in FIG. 1 , in this example, the object plane OB is inclined 25 degrees relative to the plane orthogonal to the optical axis OA. That is, when the object is a plane, even if the optical system 10 is arranged at an angle of 25 degrees, a flat image plane can be obtained relative to the object.

[0102] The optical system 10 according to this example is designed to focus on an object that is 25 mm from the lens surface closest to the object.

[0103] Figure 2 : is an aberration diagram for a wavelength of 850 nm in a focused state when the object distance is 25 mm. The object distance is the distance from the lens surface on the object surface of the lens L11, and the same applies to other embodiments. Figure 2 The aberration diagram in is measured for a wavelength of 850 nm, but the optical system 10 is also applicable to the visible region. In this case, the object distance is slightly shortened due to the wavelength dispersion of the refractive index. When seeking an object distance of 25 mm, the distance between the light receiving surface and the substrate SB2 is adjusted to be shorter.

[0104] exist Fig.11 , the size of the effective area of ​​the light receiving surface is 1.44mm×1.92mm, and the center C of the light receiving surface is 0.36mm away from the optical axis OA. The optical system IO according to this example can be used as a coaxial system in combination with a light receiving element having an effective area size of 2.16mm×1.96mm, for example.

[0105] Example 2

[0106] like Figure 3 As shown in , in this example, the object plane OB is horizontal (parallel) to the plane orthogonal to the optical axis OA.

[0107] The optical system 10 according to this example is designed to focus on an object that is 25 mm from the lens surface closest to the object.

[0108] Figure 4 This is an aberration diagram for a wavelength of 850nm in the focused state at an object distance of 25mm.

[0109] exist Fig.12, the size of the effective area of ​​the light receiving surface is 1.44 mm × 1.96 mm, and the center C of the light receiving surface is 0.72 mm away from the optical axis OA. The optical system IO according to this example can be used as a coaxial system in combination with a light receiving element whose effective area is, for example, 2.88 mm × 1.96 mm.

[0110] Example 3

[0111] like Figure 5 As shown in FIG. 1 , in this example, the object plane OB is inclined by 25° relative to the plane orthogonal to the optical axis OA. The eighth surface from the object side is inclined by 10 degrees.

[0112] The optical system 10 according to this example is designed to focus on an object that is 25 mm from the lens surface closest to the object.

[0113] Figure 6 This is the aberration diagram for a wavelength of 950nm in the focused state at an object distance of 25mm in this example.

[0114] exist Fig.13 , the size of the effective area of ​​the light receiving surface is 1.41 mm×1.41 mm, and the center C of the light receiving surface is spaced 0.5 mm from the optical axis.

[0115] The optical system in the image pickup apparatus according to this example can be used as a coaxial system in combination with a light receiving element whose effective area size is, for example, 2.12 mm×2.12 mm.

[0116] Example 4

[0117] like Figure 7 As shown in FIG. 1 , in this example, the object plane OB is inclined by 45 degrees relative to a plane orthogonal to the optical axis OA.

[0118] The optical system 10 according to this example is designed to focus on an object that is 25 mm from the lens surface closest to the object.

[0119] Figure 8 This is the aberration diagram for a wavelength of 950nm in the focused state at an object distance of 25mm in this example.

[0120] exist Fig.14 In the example, the size of the effective area of ​​the light receiving surface is 1.44mm×1.92mm, and the center C of the light receiving element surface is 0.72mm away from the optical axis. The optical system 10 according to this example can be used as a coaxial system in combination with a light receiving element having an effective area size of 2.16mm×1.96mm.

[0121] Example 5

[0122] like Fig. 9 As shown in FIG. 1 , in this example, the object plane OB is inclined by 25 degrees relative to the plane orthogonal to the optical axis OA. The eighth surface from the object side is inclined by 10 degrees.

[0123] The optical system 10 according to this example is designed to focus on an object 25 mm from the surface closest to the object.

[0124] Fig.10 This is the aberration diagram for a wavelength of 950nm in the focused state at an object distance of 25mm in this example.

[0125] exist Fig.15 , the size of the effective area of ​​the light receiving surface is 1.44mm×1.92mm, and the center C of the light receiving surface is 0.72mm away from the optical axis OA. The optical system IO according to this example can be used as a coaxial system in combination with a light receiving element having an effective area size of 2.16mm×1.96mm, for example.

[0126] Numerical Examples 1 to 5 corresponding to Examples 1 to 5 will now be illustrated.

[0127] In the surface data of each numerical example, r represents the radius of curvature of each optical surface, and d (mm) represents the on-axis distance (distance on the optical axis) between the mth surface and the (m+1)th surface, where m is the surface number counted from the light incident side. nd represents the refractive index of each optical member with respect to the d-line, and νd represents the Abbe number of the optical member. The Abbe number νd of a certain material is expressed as follows:

[0128] νd=(Nd-1) / (NF-NC)

[0129] Wherein Nd, NF and NC are the refractive indices of the d line (587.6 nm), the F line (486.1 nm) and the C line (656.3 nm) in the Fraunhofer line.

[0130] In each numerical example, d, focal length (mm), F number, and half angle of view (°) are values ​​when the optical system 10 of each example is in a state of focusing on an object at infinity. The "back focal length" is the distance on the optical axis from the final lens surface (the lens surface closest to the image plane) to the paraxial image surface expressed in air equivalent length. The "total lens length" is the length obtained by adding the back focal length to the distance on the optical axis from the frontmost surface of the optical system 10 (the lens surface closest to the object) to the final surface.

[0131] An asterisk "*" appended to the right of the surface number indicates that the optical surface is aspherical. The aspherical shape is expressed as follows:

[0132]

[0133] Where X is the displacement from the vertex of the surface in the direction of the optical axis, h is the height from the optical axis in the direction perpendicular to the optical axis, R is the paraxial curvature radius, K is the cone constant, and A4, A6, A8 and A10 are the aspheric coefficients of each order. The "e±XX" in each aspheric coefficient means "x10 ±XX ”.

[0134] Numerical Example 1

[0135] Unit: mm

[0136] Surface data

[0137]

[0138]

[0139] Aspheric surface data

[0140] First surface

[0141] K=2.35531e+01A 4=2.50149e-01A 6=-1.75859e-01A 8=1.37283e-01A10=-5.74951e-02A12=1.64602e-02

[0142] Fourth Surface

[0143] K=-5.63858e+01A 4=5.12936e+00A 6=-4.96025e+01A 8=4.80794e+02A10=-2.37635e+03A12=5.14895e+03

[0144] Seventh Surface

[0145] K=-2.17756e+00A 4=-9.82178e-01A 6=3.80210e+00A 8=-1.89409e+01A10=4.10014e+01A12=-3.00511e+01

[0146] Various data

[0147]

[0148] Numerical Example 2

[0149] Unit: mm

[0150] Surface data

[0151]

[0152] Aspheric surface data

[0153] First surface

[0154] K=-8.83070e+24A 4=5.01855e-02A 6=-2.87949e-02A 8=9.54976e-03A10=-1.88167e-03A12=1.64587e-04

[0155] Fourth Surface

[0156] K=-1.58737e+00A 4=3.26962e+00A 6=-1.95957e+01A 8=3.68431e+02A10=-2.52129e+03A12=7.56903e+03

[0157] Fifth Surface

[0158] K=0.00000e+00A 4=3.06379e-01A 6=-8.73788e-01A 8=2.12766e+01A10=-7.80674e+01

[0159] Eighth Surface

[0160] K=-8.02137e+00A 4=-2.89928e+00A 6=1.50497e+01A 8=-5.84351e+01A10=1.36717e+02A12=-1.03590e+02

[0161] Various data

[0162]

[0163] Numerical Example 3

[0164] Unit: mm

[0165] Surface data

[0166]

[0167] Aspheric surface data

[0168] First surface

[0169] K=-2.10617e+01A 4=1.74971e-01A 6=-1.44608e-01A 8=1.24732e-01A10=-6.22057e-02A12=8.82522e-03

[0170] Fourth Surface

[0171] K=-1.28664e+02A 4=5.49992e+00A 6=-5.93482e+01A 8=5.28007e+02A10=-2.36376e+03A12=4.52864e+03

[0172] Seventh Surface

[0173] K=-1.54368e+00A 4=-6.27126e-01A 6=2.12523e+00A 8=-1.08040e+01A10=1.91688e+01A12=-7.87762e+00

[0174] Various data

[0175]

[0176] Numerical Example 4

[0177] Unit: mm

[0178] Surface data

[0179]

[0180]

[0181] Aspheric surface data

[0182] The third surface

[0183] K=-3.69862e+01A 4=1.03853e+00A 6=-8.76771e+00A 8=9.31896e+01A10=-4.05184e+02A12=7.02136e+02

[0184] Sixth Surface

[0185] K=-4.05569e+00A 4=-9.48308e-01A 6=2.86374e+00A 8=-1.27932e+01A10=2.26213e+01A12=-9.63627e+00

[0186] Various data

[0187]

[0188] Numerical Example 5

[0189] Unit: mm

[0190] Surface data

[0191]

[0192]

[0193] Aspheric surface data

[0194] First surface

[0195] K=3.53565e+01A 4=1.92148e-01A 6=-1.30036e-01A 8=6.08878e-02A10=2.79929e-02A12=-2.80722e-02

[0196] Fourth Surface

[0197] K=-5.52733e+01A 4=4.73926e+00A 6=-4.67300e+01A 8=4.63193e+02A10=-2.33351e+03A12=5.09030e+03

[0198] Seventh Surface

[0199] K=-2.19034e+00A 4=-9.14325e-01A 6=2.77824e+00A 8=-1.26744e+01A10=2.32273e+01A12=-1.08360e+01

[0200] Various data

[0201]

[0202]

[0203] Table 1 summarizes the various values ​​according to each example.

[0204] Example 1 Example 2 Example 3 Example 4 Example 5 s / Rimmax 0.3 0.6 0.501494 0.3 0.3 θ(°) - - 3 - 10 Ф2i / Ф 1.274 0.986 1.289 1.225 1.278 abs(Φ1o / Φ) 0.157 0.089 0.208 - 0.079 Ф1o / Ф -0.694 -1.357 -0.614 -0.362 -0.675 Ф1o / Ф2o -0.545 -1.376 -0.476 -0.296 -0.528 d12 / f 0.457574 0.966221 0.424406 0.328992 0.442001 ω(°) 47.29378 61.91124 63.60281 39.04137 46.22662 f 1.689257 1.256852 1.763711 2.00005 1.707415 f / id 0.06757 0.050274 0.070548 0.080002 0.068297

[0205] Example 6

[0206] Fig.16A and 16B 1 is a schematic diagram of main parts of an eyepiece unit in an HMD as an example of an electronic device having one of the image pickup devices according to each example. A user views a virtual image of an image displayed on a display unit not shown through an eyepiece lens OL. The user's eye EY is illuminated by a light source LS, and the image pickup device WL acquires an image of the eye EY and an image of the light source LS reflected by the eye EY. At this time, the image pickup device WL can be as shown in FIG. Fig.16A The image is acquired through the eyepiece lens OL as shown in FIG. Fig. 16BAs shown in , an image is acquired without using the eyepiece lens OL. Here, the image pickup device WL can be any one of the image pickup devices in Examples 1 to 5. For example, when using any one of the image pickup devices in Examples 1, 3 to 5, the image pickup device WL can be deployed at an angle of 25 degrees relative to the eye EY. Even in a case where the object and the image pickup device WL are not facing each other in this way, high image quality can be obtained by using the optical system IO according to Examples 1 to 5. Thus, an image of the eye EY and an image of the light source LS reflected by the eye EY can be obtained with high clarity. An acquisition unit not shown acquires information about the user using a signal from the image pickup device WL. That is, the image pickup device WL and the acquisition unit are used as a detection system (sensing system) that performs highly accurate line of sight detection and biometric authentication such as iris authentication.

[0207] In this example, the light from the light source LS may be invisible light to prevent the user from feeling dizzy. More specifically, the emission wavelength of the light source LS may be approximately 700 nm or higher and 1100 nm or lower. When the wavelength exceeds 1100 nm, the sensitivity of the light receiving element may decrease, and the noise in the image pickup device WL may increase.

[0208] This example has described the HMD as an example of an electronic device having the image pickup device according to each example, but the electronic device may also be a viewfinder unit of a digital camera or a film-based camera.

[0209] Although the disclosure has described example embodiments, it is to be understood that some embodiments are not limited to the disclosed embodiments.The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

[0210] Each example can provide an image pickup device that is reduced in size and includes an optical system having high optical performance even when the optical system is not directly facing an object.

Claims

1. An image pickup device, comprising: An optical system comprising a first substrate and a first optical element having a refractive power disposed on the first substrate; as well as a light receiving element having a light receiving surface on which the optical system forms an image, It is characterized by satisfying the following inequality: 0.2≤s / Rimmax≤1.1 Wherein s is the distance from the intersection of the optical axis of the optical system and the light receiving surface to the center of the light receiving surface, and Rimmax is the distance from the farthest position from the center of the light receiving surface to the center.

2. The image pickup device according to claim 1, characterized in that The first optical element has a negative refractive power and is disposed on a surface of the image side of the first substrate.

3. The image pickup device according to claim 2, characterized in that: The optical system includes: a second substrate disposed adjacent to the image side of the first substrate; and A second optical element having positive refractive power is disposed on the image side of the second substrate.

4. The image pickup device according to claim 3, characterized in that: Each of the first optical element and the second optical element has an aspherical surface.

5. The image pickup device according to claim 3, characterized in that: An aperture stop is formed on the second substrate.

6. The image pickup device according to claim 3, characterized in that: The optical system also includes a third optical element disposed on the object side of the first substrate.

7. The image pickup device according to claim 6, characterized in that: The third optical element includes an aspherical surface having a positive refractive power at an end of the effective area.

8. The image pickup device according to claim 1, further comprising an optical element having a flat surface in contact with air, It is characterized in that The following inequality is satisfied: 0.5≤θ≤20.0 Here, θ is the angle [°] of the plane relative to the optical axis in the cross section having the optical axis.

9. The image pickup device according to claim 3, characterized in that: The following inequality is satisfied: 0.9≤Φ2i / Φ≤1.5 Where Φ is the refractive power of the optical system, and Φ2i is the refractive power of the second optical element.

10. The image pickup device according to claim 6, characterized in that The following inequality is satisfied: 0.0≤|Φ1o / Φ|≤0.4 Wherein Φ is the refractive power of the optical system, and Φ1o is the refractive power of the third optical element.

11. The image pickup device according to claim 3, characterized in that: The following inequality is satisfied: -1.6≤Φ1i / Φ≤-0.2 Wherein Φ is the refractive power of the optical system, and Φ1i is the refractive power of the first optical element.

12. The image pickup device according to claim 3, characterized in that: The following inequality is satisfied: -1.9≤Φ1i / Φ2i≤-0.1 Wherein Φ1i is the refractive power of the first optical element, and Φ2i is the refractive power of the second optical element.

13. The image pickup device according to claim 3, characterized in that: The following inequality is satisfied: 0.1≤d12 / f≤2.0 Wherein d12 is the distance from the surface on the image side of the first optical element to the surface on the image side of the second substrate on the optical axis, and f is the focal length of the optical system.

14. The image pickup device according to claim 1, characterized in that: The following inequality is satisfied: 35<ω<150 Wherein ω is the viewing angle [°] in the direction connecting the center of the light receiving surface and the optical axis.

15. The image pickup device according to claim 1, characterized in that: The following inequality is satisfied: 0<f≤10 Where f[mm] is the focal length of the optical system.

16. The image pickup device according to claim 1, characterized in that: The following inequality is satisfied: 0.02≤f / id≤1.0 Where f is the focal length of the optical system, and id is the distance from the surface of the optical system closest to the object to the object.

17. The image pickup device according to claim 1, further comprising a main optical system having an optical axis coinciding with a center of the light receiving surface on the light receiving surface, It is characterized in that The optical axis of the optical system is inclined relative to the optical axis of the main optical system.

18. The image pickup device according to claim 1, characterized in that: On the light receiving surface, the center of the effective area contributing to imaging does not coincide with the center of the light receiving surface.

19. An optical system comprising: a first substrate; A first optical element having a refractive power disposed on a first substrate; as well as An optical element having a flat surface in contact with air, It is characterized by satisfying the following inequality: 0.5≤θ≤20.0 Here, θ is the angle [°] of the plane relative to the optical axis in the cross section having the optical axis.

20. An image pickup device, comprising: An optical system comprising a first substrate and a first optical element having a refractive power disposed on the first substrate; as well as A light receiving element has a light receiving surface on which an optical system forms an image.

21. A detection system comprising: An image pickup device according to any one of claims 1 to 18 and 20; as well as The acquisition unit is configured to acquire information about the object using a signal from the image pickup device.

Images