Lens, lens unit, optical apparatus, imaging apparatus, and method for manufacturing lens

Abstract

To more stably provide a lens having an aspherical surface capable of photographing in a wide range.SOLUTION: In a lens including a first portion made of a first material and having a concave surface, and a second portion made of a second material and bonded to the concave surface side of the first portion, the second portion is formed in a ring shape, and a half opening angle of a light beam effective diameter is defined as an angle of 65 degrees or more and 90 degrees or less by the second portion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a lens, exemplified by a wide-angle lens used in an in-vehicle camera or the like, a lens unit including the lens, an optical instrument, an imaging device, and a method for manufacturing the lens. [Background technology]

[0002] Wide-angle lenses are often used in in-vehicle cameras and other devices to capture a wide range of images. Some wide-angle lenses use spherical surfaces to achieve a wide angle. However, such wide-angle lenses have significant aberrations in the peripheral areas of the image, making it difficult to obtain clear images. One way to address this issue is to use image software to correct the aberrations in the peripheral areas. However, there is a time lag in video processing, and it is known that correcting the aberrations in the lens itself produces clearer images. For this reason, it is believed that using aspherical lenses is more effective at correcting the aberrations described above.

[0003] Furthermore, to capture a wide range, it is more effective to use an aspherical lens with a large half-open angle on the concave side of the wide-angle lens. For example, Patent Document 1 proposes a method for making such an aspherical lens. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 3-013902 Summary of the Invention [Problem to be solved by the invention]

[0005] Known methods for producing optical elements having a structure similar to that of an aspherical lens include the replica method exemplified in Patent Document 1 and the injection molding method. However, with these conventional manufacturing methods, there is a risk that the wide-angle lens may break when released from the mold, for example, and there is a need for a stable supply of wide-angle lenses or lenses having a structure similar to that of such wide-angle lenses.

[0006] The present invention has been made in view of the above circumstances, and one of its objects is to more stably provide a lens having an aspherical surface that is capable of photographing a wide range. [Means for solving the problem]

[0007] In order to solve the above problem, a lens according to one aspect of the present invention comprises: a first portion having a concave surface and made of a first material; a second portion made of a second material adhered to the concave side of the first portion; The second portion is configured in a ring shape, and the second portion defines a half angle of the effective beam diameter at an angle of 65 degrees or more and 90 degrees or less. [Effects of the Invention]

[0008] According to one aspect of the present invention, it is possible to more stably provide a lens having an aspherical surface that is capable of capturing images over a wide range. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a wide-angle lens according to an embodiment of the present invention. [Figure 2] 1 is a diagram showing an example of a schematic configuration of a wide-angle lens manufacturing apparatus according to an embodiment of the present invention. [Figure 3] FIG. 10 is a diagram schematically illustrating an example of a mold release method using a push-up pin in a conventional manufacturing method. [Figure 4] FIG. 1 is a diagram schematically illustrating an example of a mold release method by cooling in a conventional manufacturing method. [Figure 5]1A to 1C are schematic diagrams illustrating an example of a method for manufacturing an optical lens according to an embodiment of the present invention. [Figure 6] 2 is a schematic diagram illustrating a case where parallel rays of light enter the wide-angle lens illustrated in FIG. 1. FIG. [Figure 7] 1 is a diagram showing a schematic configuration of an example of an optical instrument or an imaging device to which a wide-angle lens according to an embodiment of the present invention is applied; [Figure 8] 1 is a cross-sectional view of a wide-angle lens according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, exemplary embodiments and examples for carrying out the present invention will be described in detail with reference to the accompanying drawings. However, the dimensions, materials, and relative positions of components described in the following embodiments and examples are arbitrary, and the configuration of the device to which the present invention is applied can be changed according to various conditions. Furthermore, the same reference numerals are used between drawings to indicate identical or functionally similar elements.

[0011] Furthermore, although the present invention relates to a lens, the following embodiments and examples will describe in detail a wide-angle lens as an example of one aspect of the lens.

[0012] [Embodiment] [Wide-angle lens shape] The shape of a wide-angle lens 10 exemplified as one embodiment of the present invention will now be described. Wide-angle lens 10 has a concave shape, as shown in Fig. 1, which is a cross-sectional view taken along the optical axis. Wide-angle lens 10 shown in Fig. 1 is composed of a concave first portion 11 made of a first material, and a ring-shaped second portion 12 made of a second material bonded to the concave side of first portion 11 so as to be located at or near the circumference of the effective beam diameter.

[0013] In the wide-angle lens 10 having the illustrated shape and configuration, the thickness of the center of the recess of the first portion 11 can be, for example, 2 mm. The surface of the first portion 11 opposite the concave surface on which the recess is formed can be flat. The effective beam diameter of the concave surface of the first portion 11 in the illustrated wide-angle lens 10 can be, for example, 28 mm. Furthermore, in the illustrated wide-angle lens 10, the second portion 12 is bonded, which makes it possible to set the half-angle θ1 larger than the half-angle of the first portion 11 alone. Here, the half-angle θ1 is defined, for example, by bisecting the central angle of a sector obtained by connecting the center of an imaginary sphere constituting the arc of the concave surface with both ends of the arc. The illustrated shape and dimensions of the wide-angle lens 10 are merely examples and are not limited to those described herein.

[0014] [Wide-angle lens materials] Next, we will explain the materials that make up wide-angle lens 10. Glass, which has excellent mechanical strength and transmittance and is available in a wide variety of types, can be used as the first material that makes up first portion 11. By using a material with high mechanical strength, the thickness of the center portion of first portion 11 can be made thinner, thereby making wide-angle lens 10 thinner.

[0015] Furthermore, it is preferable to use resin as the second material constituting the second portion 12, as this material is less likely to crack during manufacturing. In this embodiment, the refractive index nd is set to 1.5 for both the first material and the second material. However, the value of the refractive index nd is not limited to the above and can be changed as appropriate depending on the application of the wide-angle lens 10, etc.

[0016] [Wide-angle lens manufacturing method] Next, a method for manufacturing the wide-angle lens 10 according to one embodiment of the present invention will be described. In the manufacturing method described below, it is preferable to use glass polished to a spherical surface for the first portion 11. Spherical glass is known to be inexpensive and to have few manufacturing issues. Furthermore, if spherical glass is used, it is possible to bond the second portion 12 without losing its shape even at high temperatures.

[0017] Here, injection molding is an example of a method for manufacturing a wide-angle lens in which the ring-shaped second portion 12 is disposed on the concave side of the first portion 11. The manufacture of wide-angle lens 10 by injection molding will be described below with reference to FIG. 2, which schematically shows the main components of a manufacturing apparatus and the cross-sectional configuration of wide-angle lens 10 during manufacture. The illustrated injection molding apparatus 20 includes a mold 21, a side mold 22, a first-section pushing member 23, a heater 24, and a push-up pin 25. Wide-angle lens 10 is formed in a space surrounded by mold 21, side mold 22, and first-section pushing member 23, and these components are sandwiched between heaters 24 to enable temperature control.

[0018] 2, in an actual manufacturing process, a first material that will become the first portion 11 is placed on a mold 21, and a side mold 22 and the first portion 11 are sandwiched between a first portion pressing member 23. Then, a second material that is passed through a runner (not shown) is poured into the space sandwiched between the first portion 11, mold 21, and side mold 22 while being heated and softened by heaters 24 that sandwich these components from above and below. This allows the mold shape of the mold 21 to be transferred to the second material while bonding the second portion 12 made of the second material to the first portion 11.

[0019] The mold 21 has an aspherical surface and a large half-open angle created by grinding and polishing, and the second portion 12 made of the second material to be transferred has an inverted shape of the mold 21. If necessary, the surface of the mold 21 can be coated with a film with excellent releasability in order to improve the releasability of the second portion 12 from the mold 21.

[0020] Thereafter, first portion 11, second portion 12, mold 21, and side mold 22 are cooled to room temperature, and mold 21 and side mold 22 are released from second portion 12. Through the above steps, wide-angle lens 10 can be manufactured, in which ring-shaped second portion 12 is disposed on the concave side of first portion 11. In this way, by preparing mold 21 with the required half-open angle, wide-angle lens 10 can be manufactured by transferring the desired shape to second portion 12.

[0021] The mold used in the exemplified injection molding method is preferably made of a material with excellent heat resistance, such as stainless steel or cemented carbide. Furthermore, it is preferable that the mold 21 has a large linear expansion coefficient, and stainless steel is preferably used. The larger the linear expansion coefficient of the mold 21 during cooling from a heat-softened state to room temperature, the less likely the second portion 12 will shrink and deform toward the mold 21, resulting in a state where the second portion 12 is sandwiched between the mold 21 and the mold 21. This reduces the stress applied to the second portion 12 during cooling.

[0022] A conventional operation for releasing wide-angle lens 110 from an injection molding apparatus will be described with reference to FIG. 3. FIG. 3 schematically illustrates the use of lift-up pins 25 to release wide-angle lens 110 from mold 21 in injection molding apparatus 120 in the state illustrated in FIG. 2. As shown in FIG. 3, when lift-up pins 25 are used, second portion 112 is lifted from the outer periphery of wide-angle lens 110 in the direction of arrow 30, for example, to release second portion 112 from mold 21. However, as the half-open angle θ1 increases, the second portion 112 contracts and grips, increasing the adhesion between second portion 112 and mold 21. This requires a large force to release them using lift-up pins 25. Therefore, when lift-up pins 25 are pushed up, the moment the adhesion at the interface between second portion 112 and mold 21 is exceeded, separation rapidly progresses. If the second material constituting second portion 112 is a viscoelastic material, the second portion 112 may become rigid, potentially causing the wide-angle lens 110 to crack.

[0023] Therefore, as shown in FIG. 4, a method of releasing second portion 112 from mold 21 without using the force of a push-up pin may be considered. In the configuration shown in FIG. 4, coolant injection nozzle 26 is provided, and coolant 27 is injected from coolant injection nozzle 26 onto the surface of first portion 111 (the surface opposite the concave surface) to cool the surface. Then, second portion 112 is slowly peeled off from mold 21 by warping the entire first portion 111 in the direction of arrow 28. However, even with this method, if half-open angle θ1 exceeds 65 degrees, for example, the warpage deformation of first portion 111 alone may not be enough to cleanly release second portion 112 from mold 21, and wide-angle lens 110 may crack.

[0024] Therefore, in the present invention, the configuration shown schematically in FIG. 5 facilitates the release of the second portion 12 from the mold 21 even for wide-angle lenses 10 with a large half-angle θ1. Specifically, as shown in FIG. 5, the second portion 12 is not provided in the center of the recess of the wide-angle lens 10, but is arranged in a ring shape only on the outer periphery. Even with this configuration, if the half-angle is less than 65 degrees, the wide-angle lens is easily released from the mold, but sufficient wide-angle performance is not achieved. If the half-angle is greater than 90 degrees, the wide-angle lens is difficult to release from the mold. In other words, by using the method shown in FIG. 5 and setting the half-angle within this range, it is possible to consistently provide wide-angle lenses with suitable half-angles. It has been confirmed that similar effects can be achieved even if the thickness of the second portion 12 provided in the center of the recess in the optical axis direction is 0.01 mm or less. Preferably, it is 0.005 mm or less. The various components in injection molding device 20 are arranged so that wide-angle lens 10 will have this shape after manufacture, and after molding second portion 12, the surface of first portion 11 is cooled to release, i.e., separate, second portion 12 from mold 21. Also, while the case where push-up pins 25 are not used has been described here, if excessive load on second portion 12 can be managed, for example, push-up pins 25 can also be used to more efficiently release the second portion 12 from mold 21.

[0025] As described above, the wide-angle lens 10 of the present invention is configured such that the second portion 12 is absent or, if present, is very thin in the center of the recess. Therefore, when the surface of the first portion 11 is cooled, the mold 21 is also cooled by heat transfer, and the warpage of the mold 21 in the direction indicated by arrow 29 can also be utilized. With a wide-angle lens 10 having the second portion 12 configured in this manner, the second portion 12 can be released from the mold 21 without cracking the wide-angle lens 10, even if the half-open angle θ1 is large. However, if the second portion 12 is also provided in the center of the recess, if the optical axis thickness is less than 0.0005 mm, high pressure is required to thin the second portion 12, which could result in an increase in the size of the device or a longer pressure time, potentially affecting costs. Therefore, if the second portion 12 is provided to the center of the recess, it is practical to set the optical axis thickness of the center of the recess to 0.0005 mm or more. In other words, if the thickness in the optical axis direction at the center of the recess is 0.0005 mm or more and 0.01 mm or less, second portion 12 can be suitably formed in wide-angle lens 10. However, when the conditions for forming second portion 12 are taken into consideration, the thickness in the optical axis direction at the center of the recess is preferably 0.002 mm or more. Furthermore, it is preferable that the shape of second portion 12 be such that the thickness in the optical axis direction inside the effective beam diameter increases toward the periphery. This is because it makes it easier to release from the mold.

[0026] The second portion 12 formed by injection molding may be subjected to heat treatment to relieve internal stress. The heat treatment method is not particularly limited, but the heating temperature during the heat treatment is preferably set to a temperature that does not cause the shape of the second portion 12 to collapse, and the heat treatment time may be set to a temperature that sufficiently relieves internal stress generated during molding. Furthermore, the injection molding method exemplified here as a manufacturing method is just one example, and a replica method may also be used.

[0027] In the wide-angle lens 10 obtained by the above method, the half aperture angle θ1 of the effective beam diameter of the second portion 12 satisfies the range of 65 degrees to 90 degrees. As a result, it is possible to obtain the aspherical concave lens with a large half aperture angle that is the objective of the present invention. Furthermore, the manufacturing method illustrated in Figure 5 makes it possible to stably provide the wide-angle lens 10 of the present invention.

[0028] The wide-angle effect of light in wide-angle lens 10 according to the present invention will now be described with reference to FIG. 6. FIG. 6 schematically shows a configuration for measuring the wide-angle effect when a laser beam is incident on wide-angle lens 10. More specifically, FIG. 6 shows the measurement state of laser light emitted from laser light source 16 entering the concave side of wide-angle lens 10 and detected and measured at exit angle θ3 by photodetector 17. When laser light enters at a half-angle θ1, it is refracted at a refraction angle θ2 and exits wide-angle lens 10 at an exit angle θ3. Note that the measurement shown in FIG. 6 shows that wide-angle lens 10 according to one embodiment of the present invention achieves a wide-angle effect of 26 degrees or more, which is more effective than conventional wide-angle effects.

[0029] However, if the half-open angle θ1 of the second portion 12 is greater than 90 degrees, the second portion 12 physically bites into the mold 21, making it impossible to separate them from the mold. Therefore, the upper limit of the half-open angle θ1 is 90 degrees or less.

[0030] [Evaluation method] Next, an evaluation method for evaluating wide-angle lenses according to examples and comparative examples to which the present invention is applied will be described using the configuration illustrated in FIG. As a method for evaluating wide-angle lenses, wide-angle lenses 10 were prepared with different half-open angles θ1 on the concave side. The prepared wide-angle lenses 10 had a first portion 11 with a concave surface and a ring-shaped second portion 12 on the concave side of first portion 11, with the surface of first portion 11 opposite the concave surface being flat.

[0031] Wide-angle lens 10 thus fabricated with the dimensions detailed below was evaluated using the method described below. Specifically, laser light capable of emitting d-line wavelength was emitted from laser light source 16 to a position Φ28 mm away from the end of effective beam range 13 on the concave side of wide-angle lens 10, forming parallel beam 14. The angle at which the laser light passed through wide-angle lens 10 and entered photodetector 17 was measured. The larger the exit angle θ3 measurable by photodetector 17, the greater the wide-angle effect of the lens. The evaluation criteria for the output angle θ3 are as follows: (Evaluation criteria for wide-angle lenses) ○: Output angle θ3 is 26 degrees or more ×: Output angle θ3 is less than 26 degrees The present invention will be described below using examples and comparative examples, but the present invention is not limited to the details described in the following examples.

[0032] [Example 1] In manufacturing the wide-angle lens 101, the concave side of the first portion 11 was first spherically machined and then cleaned. The material (first material) of the first portion 11 was N-BK7 (product name) manufactured by SCHOTT, and the first portion 11 was cleaned by placing it in an ultrasonic cleaner filled with pure water and then in a dryer to evaporate the water. A silane coupling agent was applied to the concave surface of the first portion to improve adhesion with the second portion 12, which was made of resin and used as the second material.

[0033] Next, the convex surface of the mold 21 used in injection molding was ground and polished, and then a hole was drilled to allow the second material to pass through. The mold 21 was fabricated to have an effective beam diameter of Φ28 mm, and the radius of curvature R at the effective beam diameter was 31.5 mm. STAVAX (trade name, registered trademark) manufactured by Woodeholm was used as the material for the mold 21, and the surface was coated with a carbon film to improve mold releasability. The same material was used for the side mold 22, and similar grinding and polishing and coating processes were performed to regulate the outer diameter of the first portion 11. The conditions used in this example and comparative example are summarized in Table 1.

[0034] The cleaned first portion 11, the ground and polished mold 21, and the side mold 22 were assembled as shown in Fig. 2, and the temperature of the mold 21 was then raised to 110°C using the heater 24. The heated and softened second material was then poured into the space where the second portion 12 would be formed, filling it, and then the heater 24 was turned off and the material was allowed to cool naturally to room temperature. Thereafter, as shown in Fig. 5, the surface of the first portion 11 was cooled, thereby also cooling the mold 21, causing warpage deformation in the first portion 11 and the mold 21, and the second portion 12 was released from the mold 21, thereby obtaining the wide-angle lens 101. The obtained wide-angle lens 101 had a half aperture angle θ1 of 67.019 degrees and an exit angle θ3 of 27.66 degrees, and the evaluation result was good.

[0035] [Example 2] In Example 2, the radius of curvature R at the effective diameter of the concave ray of the second portion in wide-angle lens 101 produced in Example 1 was changed to the conditions listed in Table 1. Other conditions were the same as in Example 1, and wide-angle lens 102 was obtained by the process described in Example 1. The obtained wide-angle lens 102 had a half aperture angle θ1 of 75.165 degrees and an exit angle θ3 of 30.242 degrees, and was evaluated as good.

[0036] [Example 3] In Example 3, the radius of curvature R at the effective diameter of the concave ray of the second portion in the wide-angle lens 101 produced in Example 1 was changed to the conditions listed in Table 1. The other conditions were the same as in Example 1, and a wide-angle lens 103 was obtained by the process described in Example 1. The obtained wide-angle lens 103 had a half aperture angle θ1 of 85.249 degrees and an exit angle θ3 of 32.122 degrees, and the evaluation result was good.

[0037] [Comparative Example 1] In Comparative Example 1, the radius of curvature R at the concave ray effective diameter position of the second portion in wide-angle lens 101 produced in Example 1 was changed to the conditions listed in Table 1. Other conditions were the same as in Example 1, and wide-angle lens 104 was obtained by the process described in Example 1. The obtained wide-angle lens 104 had a half angle θ1 of 61.496 degrees and an output angle θ3 of 25.568 degrees. As a result, the effect of the wide-angle lens was less than the conventional output angle θ3 of 26 degrees, so the evaluation result was ×.

[0038] The conditions of the wide-angle lenses 101 to 104 described in the above examples and comparative examples are shown in Table 1, and the evaluation results are shown in Table 2. [Table 1] [Table 2]

[0039] From the results in Table 2, it was confirmed that the wide-angle lenses 101 to 103 described in the examples had an output angle θ3 within the reference value, and were lenses with a wider angle than conventional lenses. On the other hand, the wide-angle lens 104 had an output angle θ3 of 25.568 degrees, and the effect of the wide-angle lens was less than that of the conventional output angle θ3 of 26 degrees.

[0040] From the above, the wide-angle lens in the embodiment of the present invention has a half-open angle of 65 degrees or more and 90 degrees or less within the effective beam diameter in the ring-shaped second material, which means that a lens with a wider angle than conventional lenses has been obtained.

[0041] [Application example] Next, an imaging device, which is an optical device equipped with the wide-angle lens 10 according to the embodiment described above, will be described with reference to the drawings, with an example being an on-board camera. Figure 7 shows a schematic configuration of an on-board camera according to one embodiment of the present invention, which uses the wide-angle lens 10. Figure 7(a) shows an external perspective view, and Figure 7(b) shows an outline of the components related to the optical system.

[0042] The illustrated vehicle-mounted camera 700 includes an internal optical system (lens unit 702) having multiple lenses, an image sensor 703 that receives light that has passed through the optical system, and a housing 701 that contains these components and accommodates the above-described wide-angle lens 10. It is desirable for the vehicle-mounted camera 700 to have the ability to capture as wide an area as possible, and the use of the wide-angle lens 10 according to the above-described embodiment makes it possible to meet this demand.

[0043] Furthermore, the wide-angle lens 10 is usually not used alone, but is used as a first lens to constitute a lens unit 702 including the first lens, a second lens 712, etc. The imaging element 703 is, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) image sensor. The image sensor has a function of converting light incident via the lens unit 702 into an electrical signal.

[0044] As described above, wide-angle lens 10, which is an example of a lens according to one aspect of the present invention, includes first portion 11 and second portion 12. First portion 11 has a concave surface and is made of a first material including glass. Second portion 12 is bonded to the concave surface of first portion 11. Second portion 12 is ring-shaped, and defines a half aperture angle at the effective beam diameter of wide-angle lens 10 to be between 65 degrees and 90 degrees. By forming wide-angle lens 10 in this shape, it is also possible to cool mold 21 so that cooling the surface of first portion 11 deforms mold 21, as illustrated in FIG. 5 . Furthermore, by defining a half aperture angle at the effective beam diameter to be between 65 degrees and 90 degrees using second portion 12, it is possible to more reliably release wide-angle lens 10 from mold 21.

[0045] Examples of the first material include glass, and examples of the second material include resin. The second portion 12 has a ring-like shape and can be bonded to the concave surface of the first portion 11 so that it is located near the periphery of the circle that defines the effective beam diameter of the lens. Alternatively, the second portion 12 can be bonded to the concave surface of the first portion 11 so that it is located outside the center of the circle that defines the effective beam diameter of the lens. Note that the terms "near the periphery" and "near the center" used here refer to a range that includes, for example, about 20% of the effective beam diameter on the periphery and in the radial direction centered on the periphery, or a range that includes, for example, about 80% of the effective beam diameter at the center and around the center. However, these values ​​are merely examples, and the half-open angle is not strictly defined as long as the surface of the second portion 12 that was in contact with the mold 21 and the concave surface of the first portion 11 form a continuous, smooth surface that can define the half-open angle on the circumference.

[0046] Furthermore, in a wide-angle lens according to a further aspect of the present invention, the second portion may not be ring-shaped, but may also have a portion bonded to the center of the concave surface of the first portion 11. In this case, the central thickness in the optical axis direction of the second portion bonded to the center of the concave surface of the first portion 11 is preferably 0.002 mm or more and 0.005 mm or less. By specifying the central thickness within this range, the second portion can specify the half aperture angle at the effective beam diameter to be 65 degrees or more and 90 degrees or less, and the wide-angle lens 10 can be more reliably released from the mold 21. Note that in a second portion having such a shape, the thickness in the optical axis direction inside the effective beam diameter can be configured to increase toward the outer periphery.

[0047] 7(b), the lens according to one embodiment of the present invention can be used in conjunction with a plurality of other lenses, including the lens, to form a lens unit. Also, as shown in FIGS. 7(a) and 7(b), the lens according to one embodiment of the present invention can be used in conjunction with an optical system including the lens and a housing that houses the optical system to form an optical device, such as an in-vehicle camera. Furthermore, the imaging device, such as an in-vehicle camera, can include an imaging element 703 that receives light that has passed through the optical system.

[0048] [Variations] In the above-described embodiment, the shape of the second portion 12 is such that the thickness in the optical axis direction inside the effective beam diameter increases toward the periphery. However, the shape of the second portion in the lens according to the present invention is not limited to the shape exemplified in the embodiment. An example of another shape of the second portion will now be described with reference to FIG. 8, which shows the cross-sectional shape of a lens in a format similar to FIG. 1. The lens 80 shown in FIG. 8 is configured such that the thickness of the second portion 82 decreases partially toward the periphery. As such, the shape of the second portion can be appropriately changed depending on the desired characteristics of the lens. Note that in the embodiment shown in FIG. 8, the thickness in the optical axis direction increases toward the periphery, except for aspherical shapes. Furthermore, the embodiment shown in FIG. 8 can also be described as a thickness distribution in the optical axis direction approximated by a quadratic curve that increases toward the periphery. As described above, the lens and manufacturing method thereof according to the present invention can more reliably provide a lens having an aspherical surface that is capable of photographing a wide range.

[0049] The present invention described above includes the following configurations and methods. (Configuration 1) a first portion having a concave surface and made of a first material; a second portion made of a second material adhered to the concave side of the first portion; The second portion is configured in a ring shape, and the second portion defines a half angle of an effective beam diameter of 65 degrees or more and 90 degrees or less. (Configuration 2) 2. The lens of claim 1, wherein the first material comprises glass and the second material comprises resin. (Configuration 3) The lens according to claim 1 or 2, wherein the second portion is configured to be located near the circumference of the circle of the effective beam diameter. (Configuration 4) The lens according to any one of configurations 1 to 3, wherein the second portion is configured to be positioned so as not to reach near the center of the circle of the effective beam diameter. (Configuration 5) a first portion having a concave surface and made of a first material; a second portion made of a second material adhered to the concave side of the first portion; A lens in which the center thickness of the second material is 0.0005 mm or more and 0.01 mm or less, and the half angle of the effective beam diameter is defined by the second portion at an angle of 65 degrees or more and 90 degrees or less. (Configuration 6) 7. The lens of claim 6, wherein the first material includes glass and the second material includes resin. (Configuration 7) The lens according to any one of configurations 1 to 6, wherein the thickness of the second portion in the optical axis direction inside the effective beam diameter increases toward the outer periphery. (Configuration 8) The lens according to any one of the preceding claims, wherein the center thickness of the second material is 0.002 mm or more and 0.005 mm or less. (Configuration 9) A lens unit comprising a plurality of lenses including the lens according to any one of configurations 1 to 8. (Configuration 10) an optical system including the lens according to any one of configurations 1 to 8; a housing that houses the optical system; An optical instrument comprising: (Configuration 11) an optical system including the lens according to any one of configurations 1 to 8; an image sensor that receives light that has passed through the optical system; a housing that houses the optical system and the imaging element; An imaging device comprising: (Method 1) forming a second portion with a center thickness of 0.01 mm or less from a second material between the mold and the concave surface of a first portion having a concave surface made of a first material on the side of the concave surface; cooling the first portion from a side opposite to a side on which the concave surface is formed; cooling the mold through a center of the second portion; separating the mold from the second portion by utilizing deformation of the first portion due to cooling of the first portion and deformation of the mold due to cooling of the mold; A method for manufacturing a wide-angle lens, comprising:

[0050] Although the present invention has been described above with reference to embodiments and examples, the present invention is not limited to these embodiments. Inventions modified within the scope of the present invention and inventions equivalent to the present disclosure are also included in the present invention. Furthermore, the above-described embodiments and examples can be combined as appropriate within the scope of the present invention. [Explanation of symbols]

[0051] 10, 80... wide-angle lens 11...first part 12, 82...second part 13. Effective light range (concave side) 14. Parallel rays 16. Laser light source 17. Photodetector θ1...Half-opening angle (incidence angle) θ2: Refraction angle θ3...Output angle 20...Injection molding equipment 21··· type 22...Side type 23 First extrusion member 24. Heater 25···Push-up pin 26 Coolant injection nozzle 27. Coolant

Claims

1. a first portion having a concave surface and made of a first material; a second portion made of a second material adhered to the concave side of the first portion; The second portion is configured in a ring shape, and the second portion defines a half angle of an effective beam diameter of 65 degrees or more and 90 degrees or less.

2. The lens of claim 1 , wherein the first material comprises glass and the second material comprises resin.

3. The lens of claim 1 , wherein the second portion is configured to be located near the periphery of the circle of the effective beam diameter.

4. The lens of claim 1 , wherein the second portion is configured to be positioned short of the center of the circle of effective beam diameter.

5. a first portion having a concave surface and made of a first material; a second portion made of a second material adhered to the concave side of the first portion; A lens, wherein the second material has a central thickness of 0.0005 mm or more and 0.01 mm or less, and the second portion defines a half angle of an effective beam diameter of 65 degrees or more and 90 degrees or less.

6. The lens of claim 5 , wherein the first material comprises glass and the second material comprises resin.

7. The lens according to claim 5 , wherein the thickness of the second portion in the optical axis direction inside the effective beam diameter increases toward the outer periphery.

8. The lens of claim 5 , wherein the center thickness of the second material is equal to or greater than 0.002 mm and equal to or less than 0.005 mm.

9. A lens unit comprising a plurality of lenses, including the lens according to any one of claims 1 to 8.

10. an optical system including a lens according to any one of claims 1 to 8; a housing that houses the optical system; An optical instrument comprising:

11. an optical system including a lens according to any one of claims 1 to 8; an image sensor that receives light that has passed through the optical system; a housing that houses the optical system and the imaging element; An imaging device comprising:

12. forming a second portion with a center thickness of 0.01 mm or less from a second material between the mold and the concave surface of a first portion having a concave surface made of a first material on the side of the concave surface; cooling the first portion from a side opposite to a side on which the concave surface is formed; cooling the mold through a center of the second portion; separating the mold from the second portion by utilizing deformation of the first portion due to cooling of the first portion and deformation of the mold due to cooling of the mold; A method for manufacturing a lens comprising:

Images