Molding mold, lens, lens unit, information terminal, imaging device, and molding method

Abstract

To provide a lens with improved optical properties compared to an aspherical lens. [Solution] A lens having a first optical effective surface and a second optical effective surface intersecting the optical axis, wherein at least one of the first optical effective surface and the second optical effective surface has an inflection point when moving from the intersection with the optical axis toward the edge of the effective region, the thickness distribution between the first optical effective surface and the second optical effective surface in a direction parallel to the optical axis has an extremum at a position away from the optical axis in a direction perpendicular to the optical axis, and at least one of the first optical effective surface and the second optical effective surface has a surface roughness in the first part of the lens that is greater than the surface roughness of the second part which is thicker than the first part, and the difference between the surface roughness of the first part and the surface roughness of the second part is 1.0 nmRa or more in terms of arithmetic mean roughness.

Description

Technical Field

[0001] The present disclosure relates to a mold for molding, a lens, a lens unit, an information terminal, an imaging device, and a molding method.

Background Art

[0002] In recent years, with the increase in magnification and miniaturization of imaging devices, high-precision and miniaturization of optical members have been required, and an aspherical lens having an inflection point within the effective diameter (hereinafter referred to as a "seagull lens") has been adopted. Patent Document 1 discloses a seagull lens.

[0003] As a method of manufacturing an aspherical lens made of glass, there is a technique of press-molding a molten glass material using a mold to produce a lens having a desired shape. However, when molding an aspherical lens, there is a concern that stress may concentrate on a part of the lens during mold release, causing cracks in the lens.

[0004] Patent Document 2 discloses a mold that reduces cracks in a lens during molding by making the surface roughness of the center part of the mold smaller than that of other parts when molding a glass lens whose curvature changes greatly at the center part and other places.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Aspherical lenses with an inflection point within their effective diameter have room for improvement in their optical properties. Furthermore, when manufacturing aspherical lenses with an inflection point within their effective diameter using a mold to shape the glass, cracking can easily occur depending on the lens shape. [Means for solving the problem]

[0007] Therefore, one of the objectives of this disclosure is to provide a technology that can improve the optical properties of aspherical lenses. Furthermore, one of the objectives of this disclosure is to provide a technology that can suppress the occurrence of cracks during the molding of aspherical lenses.

[0008] A first embodiment of the present disclosure is a lens having a first optical effective surface and a second optical effective surface intersecting an optical axis, wherein at least one of the first optical effective surface and the second optical effective surface has an inflection point when moving from the intersection with the optical axis toward the edge of the effective region, the thickness distribution between the first optical effective surface and the second optical effective surface in a direction parallel to the optical axis has an extremum at a position away from the optical axis in a direction perpendicular to the optical axis, and at least one of the first optical effective surface and the second optical effective surface has a surface roughness in the first portion of the lens that is greater than the surface roughness of the second portion which is thicker than the first portion, and the difference between the surface roughness of the first portion and the surface roughness of the second portion is 1.0 nmRa or greater in terms of arithmetic mean roughness.

[0009] A second embodiment of the present disclosure is a molding die comprising a pair of first and second members used for press-forming a lens having a first optically effective surface and a second optically effective surface intersecting an optical axis, wherein at least one of the first optically effective surface and the second optically effective surface has an inflection point when moving from the intersection with the optical axis toward the edge of the effective region, and the thickness distribution between the first optically effective surface and the second optically effective surface in a direction parallel to the optical axis has an extremum at a position away from the optical axis in a direction perpendicular to the optical axis, wherein at least one of the first and second members has a surface roughness in a first corresponding portion corresponding to a first portion of the lens that is greater than the surface roughness of a second corresponding portion corresponding to a second portion of the lens that is thicker than the first portion of the lens. [Effects of the Invention]

[0010] According to the first embodiment of this disclosure, the optical properties of an aspherical lens can be improved. Furthermore, according to the second embodiment of this disclosure, the occurrence of cracks during the molding of an aspherical lens can be suppressed. [Brief explanation of the drawing]

[0011] [Figure 1] An example of a lens according to Embodiment 1 of this disclosure and an example of the lens thickness distribution are shown. [Figure 2] This is an illustrative diagram showing a lens molding method using a mold according to Embodiment 1 of the present disclosure. [Figure 3] This is a diagram illustrating the surface roughness measurement position of the mold according to Embodiment 1 of this disclosure. [Figure 4] An example of the surface roughness of a mold according to Embodiment 1 of this disclosure is shown. [Figure 5] An example of a lens unit according to Embodiment 2 of this disclosure is shown. [Figure 6] An example of an information terminal relating to Embodiment 3 of this disclosure is shown. [Figure 7] An example of an imaging device according to Embodiment 4 of this disclosure is shown. [Modes for carrying out the invention]

[0012] Hereinafter, exemplary embodiments and examples for implementing the present disclosure will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative positions of components, etc. described in the following embodiments and examples are arbitrary and can be changed according to the configuration of the device to which the present disclosure is applied or various conditions. Also, in the drawings, the same reference numerals are used between the drawings to indicate elements that are identical or functionally similar.

[0013] (Embodiment 1) [Configuration of the lens] Referring to FIGS. 1(a) and 1(b), the lens according to Embodiment 1 of the present disclosure will be described. The lens has two optically effective surfaces (a first optically effective surface and a second optically effective surface) that each intersect the optical axis. One of the two optically effective surfaces is the light incident surface and is the optically effective surface on the object side, which is referred to as the object side surface. The other optically effective surface is the light exit surface and is the optically effective surface on the imaging side, which is referred to as the imaging side surface. The entire surface of the optically effective surface is the effective region through which the light rays that are effectively imaged pass. The end of the effective region of the lens refers to the end of the optical effective region of the lens, and the optical effective region of the lens refers to the region having predetermined optical characteristics in the lens. The light incident surface or the light exit surface of the lens may have an ineffective region through which the light rays that are not effectively imaged pass. The surface of the lens may have an ineffective region through which the light rays do not pass in the optical system. The boundary between the effective region and the ineffective region is the end of the effective region.

[0014] The lens according to the present embodiment can be formed using a mold and may be a glass lens using glass such as borosilicate glass, lanthanum glass, or fluoroaluminate glass as the material. Also, the lens according to the present embodiment can be formed using a mold and may be a plastic lens using plastics such as cyclic olefin polymer, polycarbonate, or acrylic resin as the material.

[0015] The lens according to this embodiment can be formed as a so-called seagull lens, which has an inflection point within its effective diameter. Specifically, a seagull lens has an inflection point along the optical axis, at least one of the contour lines of the object side and the image-forming side of the lens cross-section containing the optical axis, when moving from the intersection of the contour line and the optical axis toward the edge of the lens's effective region. In other words, at least one of the object side and the image-forming side has an inflection point when moving from the intersection with the optical axis toward the edge of the effective region. Furthermore, in a seagull lens, the thickness distribution between the object side and the image-forming side in the direction parallel to the optical axis (optical axis direction) has an extremum at a position away from the optical axis in the direction perpendicular to the optical axis (radial direction), i.e., other than the intersection of the lens and the optical axis. A position having an extremum is called an extremum position. That is, the relationship (function) of the thickness at that position with respect to the position in the radial direction has an extremum of thickness at the extremum position.

[0016] Figure 1(a) shows an example of a lens according to this embodiment, and Figure 1(b) shows an example of the thickness distribution of the lens according to this embodiment. As shown in Figure 1(a), lens 1 according to this embodiment has inflection points 102 and 103 along the optical axis, in the contour line on the imaging side of the lens cross-section containing the optical axis, when moving from the intersection point 101 of the contour line and the optical axis toward the effective area edges 104 and 105 of the lens. Furthermore, as shown in Figure 1(b), the thickness distribution 110 between the object side surface and the imaging side surface in a direction parallel to the optical axis has extreme points 112 and 113 in addition to the point 111 corresponding to the intersection point of the lens and the optical axis. Note that Figure 1(b) also shows the effective area edges 114 and 115 of the thickness distribution 110 corresponding to the effective area edges 104 and 105.

[0017] Note that the configuration of the lens 1 is an example, and the lens according to the present embodiment may have an inflection point when moving from the intersection of the contour line and the optical axis to the end of the effective region of the lens at the object-side contour line of the lens cross-section including the optical axis along the optical axis. Also, the lens 1 shown in Fig. 1(a) has a concave surface on the imaging side and a convex surface on the object side in the vicinity of the center, but the shape of the lens according to the present embodiment is not limited to this. The lens according to the present embodiment may have a convex surface on the imaging side and a concave surface on the object side in the vicinity of the center, or both surfaces may be concave, or both surfaces may be convex.

[0018] Also, in the lens 1, the surface roughness of at least one of the object-side surface and the imaging-side surface in the relatively thin portion of the lens 1 is greater than the surface roughness in other portions. In other words, the surface roughness of at least one of the object-side surface and the imaging-side surface in the first portion of the lens 1 is greater than the surface roughness in the second portion that is thicker than the first portion.

[0019] Here, as a shape with a large surface roughness, for example, a shape with a large arithmetic mean roughness of the surface or a shape with a high spatial frequency of the extreme value of the power spectral density (PSD) on the surface can be considered. When the evaluation index is Ra, the measurement range is set as a measurement range centered on the corresponding point. The measurement range is preferably 10 μm or more, 25 μm or more, or 60 μm or more, and preferably 1000 μm or less, 600 μm or less, or 250 μm or less. When the evaluation index is PSD, the surface roughness within a square region of 600 μm 2 or more and 0.06 mm 2 or less is preferably used. Not limited to this, the surface roughness within a square region of 100 μm 2 ~0.01 mm 2 or 0.01 mm 2 ~1 mm 2 centered on the corresponding point may also be used.

[0020] Power spectral density is a spectral function that expresses roughness as a power value per unit frequency width, independent of frequency resolution Δf. In this specification, power spectral density (PSD) is expressed in logarithmic notation. Furthermore, in this specification, the spatial frequencies of the PSD extrema in spatial frequencies from 6000 [1 / mm] to 10000 [1 / mm] are described, but the spatial frequency range for the PSD extrema is not limited to spatial frequencies from 6000 [1 / mm] to 10000 [1 / mm] and may be changed according to the desired configuration.

[0021] Therefore, lens 1 may have a configuration in which, for example, the arithmetic mean roughness of at least one of the object-side surface and the image-forming surface in the portion of lens 1 that is relatively thin is greater than the arithmetic mean roughness in the other portions. Also, lens 1 may have a configuration in which, for example, the surface roughness is based on the power spectral density, and in the spatial frequency range of 6000 [1 / mm] to 10000 [1 / mm] expressed by the power spectral density, the spatial frequency at which the power spectral density of the relatively thin portion reaches its extreme value is higher than the spatial frequency at which the power spectral density of the other portions reaches its extreme value.

[0022] In seagull lenses with large thickness variations, there was a concern that the optical properties would deteriorate due to the expansion of the light intensity distribution, as the amount of absorbed transmitted light would be greater in thicker parts and smaller in thinner parts, according to the Lambert-Beer law. In lens 1 according to this embodiment, scattering in the thicker parts is small due to the small surface roughness of the thicker parts. Therefore, in the thicker parts, the reduction in the amount of transmitted light is smaller compared to the thinner parts with larger surface roughness, and the expansion of the light intensity distribution within the lens surface can be suppressed. From this viewpoint, the significant difference in surface roughness between parts being compared within one optically effective surface (first part and second part) can be 1.0 nmRa or more in arithmetic mean roughness. Two parts where the difference in surface roughness within one optically effective surface is less than 1.0 nmRa in arithmetic mean roughness is not effective from the viewpoint of suppressing the expansion of the light intensity distribution within the optically effective surface. The difference in surface roughness between parts being compared within one optically effective surface (first part and second part) may be 10 nmRa or less in arithmetic mean roughness. When the difference in surface roughness exceeds 10 nmRa in arithmetic mean roughness, the degree of freedom in lens design for obtaining desired optical properties may decrease.

[0023] Furthermore, when press molding is performed using a mold on a Kamome lens with large thickness variations, there was a concern that stress would easily accumulate in a part of the lens during demolding due to differences in thermal shrinkage proportional to the lens thickness, potentially causing cracking. In the lens 1 according to this embodiment, during press molding, demolding progresses faster in the thinner parts due to the greater surface roughness. By accelerating the demolding progress in the thinner parts of the lens 1, the demolding progress of the lens 1 can be controlled, suppressing sudden stress changes during molding and preventing cracking of the lens 1 during molding.

[0024] [Method for forming glass lenses] Next, with reference to Figure 2, a molding die for heating and softening a glass component and a method for molding a glass lens will be described. Figure 2 is an illustrative diagram illustrating the molding method using the die according to this embodiment.

[0025] The mold 4 according to this embodiment includes a first member 2 and a second member 3. The first member 2 and the second member 3 are mold members for transferring the shape of the optically effective surface of the lens 1 to be molded, and their shape is cylindrical. Therefore, the lens 1 molded using the mold 4 can have a shape corresponding to the shapes of the first member 2 and the second member 3 that come into contact with it during molding. For example, the lens 1 molded using the mold 4 can have a surface roughness on the surface that comes into contact with the first member 2 during molding that corresponds to the surface roughness of the first member 2, as described below. Similarly, the lens 1 molded using the mold 4 can have a surface roughness on the surface that comes into contact with the second member 3 during molding that corresponds to the surface roughness of the second member 3, as described below. The first member 2 and the second member 3 can be constructed using, for example, cemented carbide as the material to suppress mold wear. In addition, a material harder than cemented carbide may be deposited on the surfaces of the first member 2 and the second member 3. Furthermore, the shapes of the first member 2 and the second member 3 are not limited to cylindrical shapes, but may be any shape depending on the desired configuration.

[0026] The mold 4 has a drive system (not shown), and during press forming, at least one of the first member 2 and the second member 3 can be moved vertically to form the lens 1. Here, as an example of a method for forming the lens 1 using the mold 4 according to this embodiment, a method of press forming will be described. Note that the following forming method is just an example, and the lens 1 may be formed by any known forming method that can form the shape of both sides of the lens using the mold members.

[0027] In the molding method according to this embodiment, first, the mold 4 is heated, and then the lens preform 1 is placed in the mold 4. Then, the mold 4 and the preform are further heated to soften the viscosity of the preform to a state suitable for press molding. Next, at least one of the first member 2 and the second member 3 is moved vertically to press the preform, bringing the mold 4 and the preform into contact and molding the preform into the desired shape of the lens 1. Finally, the temperature of the mold 4 is lowered, and when the temperature of the mold 4 falls below a predetermined temperature, the applied load is removed. When the load is removed, the lens 1, which had been compressed, becomes deformable, and the lens 1 can be released from the mold 4.

[0028] Here, at least one of the first member 2 and the second member 3 has a surface roughness greater than the surface roughness of the other parts of the at least one in the portion corresponding to the relatively thin portion of the lens 1. In other words, the at least one has a surface roughness greater in the portion corresponding to the first portion of the lens 1 (first corresponding portion) than in the portion corresponding to the second portion (second corresponding portion) which is thicker than the first portion of the molded lens 1. Note that the portion of the lens 1 (for example, the relatively thin portion of the molded lens 1) in at least one of the first member 2 and the second member 3 may be the portion that comes into contact with that portion of the lens 1 during the molding of the lens 1. Here, the difference between the surface roughness of the first corresponding portion and the surface roughness of the second corresponding portion can be 1.0 nmRa or more in arithmetic mean roughness. Also, the difference between the surface roughness of the first corresponding portion and the surface roughness of the second corresponding portion can be 10 nmRa or less in arithmetic mean roughness.

[0029] More specifically, in this embodiment, at least one of the first member 2 and the second member 3 has a surface roughness in the portion of the point group in the thickness distribution of the glass lens, which includes points corresponding to the intersection of the glass lens and the optical axis, effective region endpoints, and points with extreme values, where the thickness of the glass lens is minimum, that corresponds to the portion of the point group where the thickness of the glass lens is maximum, which is greater than the surface roughness in the portion of the point group where the thickness of the glass lens is maximum.

[0030] With this configuration, in the mold 4 according to this embodiment, when press-molding the lens 1, the demolding progresses faster in the parts of the lens 1 corresponding to the thinner parts due to the greater surface roughness. By accelerating the demolding progress in the thinner parts of the lens 1, the demolding progress of the lens 1 can be controlled, sudden stress changes during molding can be suppressed, cracking of the lens 1 during molding can be suppressed, and a glass lens with suppressed light intensity distribution expansion can be manufactured.

[0031] Here, at least one of the first member 2 and the second member 3 may have an arithmetic mean roughness greater than the arithmetic mean roughness of the other part of the at least one in the portion corresponding to the relatively thin portion of the lens 1. Furthermore, the surface roughness of the at least one may have a configuration in which, for example, in the spatial frequency range of 6000 [1 / mm] to 10000 [1 / mm] expressed in terms of power spectral density, the spatial frequency at which the power spectral density of the portion corresponding to the relatively thin portion of the lens 1 reaches its extreme value is higher than the spatial frequency at which the power spectral density of the other part of the at least one reaches its extreme value.

[0032] Furthermore, the surface roughness of at least one of the first member 2 and the second member 3 may be varied in steps. For example, the surface roughness of at least one of the first member 2 and the second member 3 can be varied in two steps: one corresponding to a relatively thin portion of the molded lens 1 and the other portion. Alternatively, the surface roughness of at least one of the first member 2 and the second member 3 may be varied in three or more steps. By gradually changing the surface roughness of the mold members according to the thickness of the molded lens 1, the timing of demolding can be controlled more appropriately. This suppresses sudden stress changes during molding, reduces the occurrence of cracks in the glass lens, and allows for the manufacture of a glass lens with suppressed light intensity distribution expansion.

[0033] Furthermore, in this embodiment, at least one of the first member 2 and the second member 3 can have a surface roughness in the portion corresponding to a third portion of the molded lens 1 that is thicker than the first portion and thinner than the second portion, such that the surface roughness is smaller than that of the portion corresponding to the first portion and larger than that of the portion corresponding to the second portion. With this configuration, the surface of the mold member has a surface roughness corresponding to the relative thickness of the molded lens 1, which allows for more appropriate control of the timing of demolding. This suppresses sudden stress changes during molding, reduces the occurrence of cracks in the glass lens, and enables the manufacture of a glass lens with suppressed light intensity distribution expansion.

[0034] Furthermore, the surface roughness of at least one of the first member 2 and the second member 3 may change continuously. For example, at least one of the first member 2 and the second member 3 may have a surface roughness corresponding to the thickness of the lens 1 after molding. More specifically, at least one of the first member 2 and the second member 3 may have a surface roughness such that the surface roughness corresponding to the thinner part of the lens 1 after molding increases. With such a configuration, the surface of the mold member has a surface roughness corresponding to the relative thickness of the lens 1 after molding, which allows for more appropriate control of the timing of demolding. This suppresses sudden stress changes during molding, reduces the occurrence of cracks in the glass lens, and enables the manufacture of a glass lens with suppressed light intensity distribution expansion.

[0035] Methods for imparting surface roughness to the mold 4 include, for example, laser processing, ion beam processing, polishing, and blasting. However, the method for imparting surface roughness to the mold 4 is not limited to these, and any method may be used depending on the desired configuration. In addition to transferring surface roughness by molding using the mold 4, any method may be used to impart surface roughness to the lens 1, such as, for example, laser processing, ion beam processing, polishing, and blasting, depending on the desired configuration.

[0036] Furthermore, the surface roughness of lens 1, including the surface roughness at its thickest and thinnest points, can be set to an arithmetic mean roughness of, for example, 2 nmRa to 12 nmRa. In such cases, lens 1 can have a transmittance suitable for use as an optical lens. In addition, the difference between the maximum and minimum thickness of lens 1 can be set to, for example, 0.4 mm to 5.0 mm. By setting the difference between the maximum and minimum thickness of lens 1 to 5.0 mm or less, it is possible to adjust the surface roughness of lens 1 to equalize its transmittance. Also, by setting the difference between the maximum and minimum thickness of lens 1 to 0.4 mm or more, the effect of the seagull-shaped lens (for example, the amount of light bent) can be appropriately realized when lens 1 is used as an optical lens.

[0037] [Method for measuring light intensity distribution] Next, a method for measuring the light intensity distribution of lens 1 according to this embodiment will be described. First, light emitted from a light source is passed through lens 1 and projected onto a projection surface. Then, the light intensity distribution is obtained by measuring the projected light using, for example, a two-dimensional imaging colorimeter. An illuminometer or luminance meter may also be used for measurement. Alternatively, a lens unit may be created using the molded lens 1, and the light intensity distribution may be obtained from the imaging results.

[0038] [Method for evaluating the surface roughness of molds] Next, an evaluation method for evaluating the surface roughness of the mold 4 according to this embodiment will be described. Figure 3 is a diagram illustrating the measurement position of the surface roughness of the mold 4 according to this embodiment, and is a cross-sectional view of an example of the first member 2 of the mold 4 along the optical axis of the lens 1 to be molded. Note that the thickness distribution 310 shown in Figure 3 represents the thickness distribution within the effective region of the thickness distribution 110 shown in Figure 1.

[0039] First, the thickness distribution 310 in the optical axis direction of the molded lens 1 is obtained. The method for obtaining the thickness distribution 310 may be any known method; for example, the thickness distribution 310 may be obtained using a known thickness measuring device. On the thickness distribution 310, as shown in Figure 3, there is a point group that includes a point 311 corresponding to the intersection with the optical axis, an effective region endpoint 314, and an extreme value point 312. Here, the radial position corresponding to the point 311 corresponding to the intersection with the optical axis is the optical axis position. Also, the radial position corresponding to the extreme value point 312 is the extreme value position. During molding, the lens 1 comes into contact with the point 201 corresponding to the thickest point and the point 202 corresponding to the thinnest point on the surface of the first member 2 at the positions corresponding to the thickest and thinnest points among the radial positions corresponding to the point group. For this reason, the point 201 corresponding to the thickest point and the point 202 corresponding to the thinnest point of the lens 1 are set as points for evaluating the surface roughness of the first member 2. Furthermore, as a point for evaluating the surface roughness of the first member 2, an arbitrary point 203 is set from a position other than point 201, which corresponds to the thickest point within the effective diameter, and point 202, which corresponds to the thinnest point. Here, point 203 corresponds to point 316 on the thickness distribution 310.

[0040] Next, the surface roughness of the first member 2 at points 201, 202, and 203 is measured, for example, using a contact-type roughness meter. This allows for the evaluation of the arithmetic mean roughness (Ra) or power spectral density (PSD) at each of points 201, 202, and 203 of the first member 2 of the mold 4.

[0041] This document describes an evaluation method for assessing the surface roughness of the first component 2, but the surface roughness of the second component 3 may be evaluated using a similar method. Furthermore, the evaluation index for surface roughness is not limited to arithmetic surface roughness or power spectral density, but may be any other known evaluation index. Note that depending on the shape of the sample to be evaluated (e.g., mold 4), measurement may be difficult due to interference between the sample and the measuring instrument. In such cases, a flat sample with roughness applied under similar conditions may be used as an alternative for evaluation.

[0042] Hereinafter, the lens, molding die, and molding method according to Embodiment 1 of this disclosure will be described using examples and comparative examples. Examples 1 to 5, in which a glass lens having a desired arithmetic mean roughness was obtained by intentionally imparting a desired arithmetic mean roughness to the surface of the mold 4, and Examples 6 to 10, in which a glass lens having a desired PSD was obtained by intentionally imparting a desired PSD to the surface of the mold 4, will be described. Comparative examples 1 to 5, in which a glass lens having a desired arithmetic mean roughness was obtained by intentionally imparting a desired arithmetic mean roughness to the surface of the mold 4, and Comparative examples 6 to 10, in which a glass lens having a desired PSD was obtained by intentionally imparting a desired PSD to the surface of the mold 4, will be described.

[0043] The process of imparting surface roughness to the mold 4 according to this embodiment will be explained below using Figures 4(a) to 4(d). Figures 4(a) and 4(b) show an example of arithmetic mean roughness at a point on the mold surface according to this embodiment, and Figures 4(c) and 4(d) show an example of logarithmically expressed PSD at a point on the mold surface according to this embodiment.

[0044] In Examples 1 to 5, the mold 4 was subjected to a surface roughening process such that the arithmetic mean roughness 401 at the point on the mold surface in contact with the thinnest point of the lens during molding, as shown in Figure 4(a), was greater than the arithmetic mean roughness 402 at the point on the mold surface in contact with the thickest point of the lens during molding, as shown in Figure 4(b). Furthermore, in Examples 6 to 10, the mold 4 was subjected to a surface roughening process such that the spatial frequency of the extreme value 403 of the PSD in the spatial frequency range of 6000 [1 / mm] to 10000 [1 / mm] at the point on the mold surface in contact with the thinnest point of the lens during molding, as shown in Figure 4(c), was higher than the spatial frequency of the extreme value 404 of the PSD in the same spatial frequency range at the point on the mold surface in contact with the thickest point of the lens during molding, as shown in Figure 4(d). Note that this disclosure is not limited to the following examples.

[0045] First, Examples 1 to 5 and Comparative Examples 1 to 5, in which the surface roughness of the mold 4 was given a desired arithmetic mean roughness, will be described.

[0046] (Example 1) In Example 1, a glass lens with a double-sided concave shape near the center was formed. A pair of molds 4 were prepared such that the thickness at the thickest point of the lens was 3.5 mm, the thickness at the thinnest point was 1.2 mm, and the thickness at any point selected from locations other than the thickest and thinnest points was 2.0 mm.

[0047] In this embodiment, surface roughness was applied to both the first member 2 and the second member 3 of the mold 4. Specifically, the surface roughness of the mold 4 at the point of contact with the thickest point of the molded lens was 2.0 nmRa, the surface roughness of the mold 4 at the point of contact with the thinnest point was 7.0 nmRa, and the surface roughness of the mold 4 at the point of contact with any selected point was 3.4 nmRa.

[0048] The molding process was carried out using mold 4 as follows. Optical glass for glass molding with a glass dislocation temperature of 615°C was used as the preform. An infrared heater was used to heat mold 4 and the preform. First, mold 4 was heated to a first temperature (580°C), and then the preform was placed in the mold. Then, mold 4 and the preform were heated to a second temperature (680°C), which was higher than the first temperature, to soften the viscosity of the preform to a state suitable for press molding. Next, the mold 4 and the preform were pressed with a first load (4000N) to bring them into contact and mold the preform into the desired shape of a glass lens. Finally, when mold 4 reached a temperature lower than the second temperature (580°C), the applied load was removed. When the load was removed, the glass lens, which had been compressed, became deformable, and the glass lens was released from mold 4.

[0049] In this embodiment, crack-free glass lenses were successfully formed under these molding conditions. Furthermore, when the surface roughness of the thickest and thinnest points of the molded lens was measured, it was confirmed that the surface roughness of the thinnest point was greater than that of the thickest point, and that there was virtually no light intensity distribution. In addition, when a lens unit was fabricated using the molded lens and mounted on an information terminal, it was confirmed that good imaging performance was obtained.

[0050] (Example 2) In Example 2, a glass lens with a concave shape on one side and a convex shape on the other near the center was formed. A pair of molds 4 were prepared such that the thickness at the thickest point of the lens was 1.0 mm, the thickness at the thinnest point was 0.6 mm, and the thickness at any point selected from locations other than the thickest and thinnest points was 0.7 mm.

[0051] In this embodiment, surface roughness was applied to both the first member 2 and the second member 3 of the mold 4. Specifically, the surface roughness of the mold 4 at the point of contact with the thickest point of the molded lens was 3.1 nmRa, the surface roughness of the mold 4 at the point of contact with the thinnest point was 5.6 nmRa, and the surface roughness of the mold 4 at the point of contact with any selected point was 4.8 nmRa.

[0052] Using this mold 4, molding was performed in the same manner as in Example 1. In this example as well, a glass lens without cracks was formed. Furthermore, when the roughness of the thickest and thinnest points of the molded lens was measured, it was confirmed that the roughness of the thinnest point was greater than that of the thickest point, and it was also confirmed that the light intensity distribution was small (narrow).

[0053] (Example 3) In Example 3, a glass lens with a double-sided convex shape near the center was formed. A pair of molds 4 were prepared such that the thickness at the thickest point of the lens was 4.6 mm, the thickness at the thinnest point was 0.5 mm, and the thickness at any point selected from locations other than the thickest and thinnest points was 3.0 mm.

[0054] In this embodiment, surface roughness was applied only to the first component 2 of the mold 4. Specifically, the surface roughness of the mold 4 at the point of contact with the thickest point of the molded lens was 5.7 nmRa, the surface roughness of the mold 4 at the point of contact with the thinnest point was 9.5 nmRa, and the surface roughness of the mold 4 at the point of contact with any selected point was 7.2 nmRa.

[0055] Using this mold 4, molding was performed in the same manner as in Example 1. In this example as well, a glass lens without cracks was formed. Furthermore, when the roughness of the thickest and thinnest points of the molded lens was measured, it was confirmed that the roughness of the thinnest point was greater than that of the thickest point, and it was also confirmed that there was virtually no light intensity distribution.

[0056] (Example 4) In Example 4, a glass lens with a concave shape on one side and a convex shape on the other near the center was formed. A pair of molds 4 were prepared such that the thickness at the thickest point of the lens was 5.3 mm, the thickness at the thinnest point was 2.1 mm, and the thickness at any point selected from locations other than the thickest and thinnest points was 3.6 mm.

[0057] In this embodiment, surface roughness was applied only to the first component 2 of the mold 4. Specifically, the surface roughness of the mold 4 at the point of contact with the thickest point of the molded lens was 2.4 nmRa, the surface roughness of the mold 4 at the point of contact with the thinnest point was 6.9 nmRa, and the surface roughness of the mold 4 at the point of contact with any selected point was 10.6 nmRa.

[0058] Using this mold 4, molding was performed in the same manner as in Example 1. In this example, some cracking was observed, but the molding was performed at a level that was acceptable according to specifications. Furthermore, when the roughness of the thickest and thinnest points of the molded lens was measured, it was confirmed that the roughness of the thinnest point was greater than that of the thickest point, and that there was virtually no light intensity distribution.

[0059] (Example 5) In Example 5, a glass lens with a concave shape on one side and a convex shape on the other near the center was formed. A pair of molds 4 were prepared such that the thickness at the thickest point of the lens was 2.3 mm, the thickness at the thinnest point was 1.4 mm, and the thickness at any point selected from locations other than the thickest and thinnest points was 1.7 mm.

[0060] In this embodiment, surface roughness was applied only to the second component 3 of the mold 4. Specifically, the surface roughness of the mold 4 at the point of contact with the thickest point of the molded lens was 3.8 nmRa, the surface roughness of the mold 4 at the point of contact with the thinnest point was 6.5 nmRa, and the surface roughness of the mold 4 at the point of contact with any selected point was 1.1 nmRa.

[0061] Using this mold 4, molding was performed in the same manner as in Example 1. In this example as well, some cracks were observed, but the molding was performed at a level that was acceptable according to specifications. Furthermore, when the roughness of the thickest and thinnest points of the molded lens was measured, it was confirmed that the roughness of the thinnest point was greater than that of the thickest point, and that the light intensity distribution was small.

[0062] (Comparative Example 1) In Comparative Example 1, a glass lens with the same shape as in Example 1 was formed. In this comparative example, surface roughness was applied to both the first component 2 and the second component 3 of the mold 4. Specifically, the surface roughness of the mold 4 at the point of contact with the thickest point of the formed lens was 8.0 nmRa, the surface roughness of the mold 4 at the point of contact with the thinnest point was 4.0 nmRa, and the surface roughness of the mold 4 at the point of contact with an arbitrary point of selection was 3.2 nmRa.

[0063] Molding was performed using this mold 4 in the same manner as in Example 1. In this comparative example, some cracking was observed, but the molding was performed at a level that did not pose a problem according to the specifications. Furthermore, when the roughness of the thickest and thinnest points of the molded lens was measured, it was confirmed that the roughness of the thinnest point was greater than that of the thickest point, but the light intensity distribution was large and did not pose a problem according to the specifications.

[0064] (Comparative Example 2) In Comparative Example 2, a glass lens with the same shape as in Example 2 was formed. In this comparative example, surface roughness was applied to both the first component 2 and the second component 3 of the mold 4. Specifically, the surface roughness of the mold 4 at the point of contact with the thickest point of the formed lens was 3.1 nmRa, the surface roughness of the mold 4 at the point of contact with the thinnest point was 1.2 nmRa, and the surface roughness of the mold 4 at the point of contact with any selected point was 1.5 nmRa.

[0065] Molding was performed using mold 4 in the same manner as in Example 1. In this comparative example, when mold 4 reached a temperature lower than the second temperature (580°C), the applied load was removed, but cracking occurred, and molding could not be completed. Because molding could not be completed, the light intensity distribution could not be measured.

[0066] (Comparative Example 3) In Comparative Example 3, a glass lens with the same shape as in Example 3 was molded. In this comparative example, only the first component 2 of the mold 4 was processed to impart surface roughness. Specifically, the surface roughness of the mold 4 at the point of contact with the thickest point of the molded lens was 5.7 nmRa, the surface roughness of the mold 4 at the point of contact with the thinnest point was 2.1 nmRa, and the surface roughness of the mold 4 at the point of contact with an arbitrary point of selection was 3.3 nmRa.

[0067] Molding was performed using mold 4 in the same manner as in Example 1. In this comparative example, when mold 4 reached a temperature lower than the second temperature (580°C), the applied load was removed, but cracking occurred, and molding could not be completed. Because molding could not be completed, the light intensity distribution could not be measured.

[0068] (Comparative Example 4) In Comparative Example 4, a glass lens with the same shape as in Example 4 was molded. In this comparative example, only the first component 2 of the mold 4 was processed to impart surface roughness. Specifically, the surface roughness of the mold 4 at the point of contact with the thickest point of the molded lens was 12.4 nmRa, the surface roughness of the mold 4 at the point of contact with the thinnest point was 6.9 nmRa, and the surface roughness of the mold 4 at the point of contact with an arbitrary point of selection was 10.6 nmRa.

[0069] Molding was performed using mold 4 in the same manner as in Example 1. In this comparative example, when mold 4 reached a temperature lower than the second temperature (580°C), the applied load was removed, but cracking occurred, and molding could not be completed. Because molding could not be completed, the light intensity distribution could not be measured.

[0070] (Comparative Example 5) In Comparative Example 5, a glass lens with the same shape as in Example 5 was molded. In this comparative example, only the second component 3 of the mold 4 was processed to impart surface roughness. Specifically, the surface roughness of the mold 4 at the point of contact with the thickest point of the molded lens was 7.8 nmRa, the surface roughness of the mold 4 at the point of contact with the thinnest point was 6.5 nmRa, and the surface roughness of the mold 4 at the point of contact with an arbitrary point of selection was 1.1 nmRa.

[0071] Molding was performed using mold 4 in the same manner as in Example 1. In this comparative example, when mold 4 reached a temperature lower than the second temperature (580°C), the applied load was removed, but cracking occurred, and molding could not be completed. Because molding could not be completed, the light intensity distribution could not be measured.

[0072] Table 1 below shows the glass lens shape, surface roughness measurement results of mold 4, light intensity distribution of the lens, and cracking results (degree of cracking) during molding for Examples 1 to 5 and Comparative Examples 1 to 5. As an evaluation criterion for the light intensity distribution of the lens, C is defined as no light intensity distribution can be confirmed, B is defined as some light intensity distribution can be confirmed but does not pose a problem according to the specifications, and A is defined as light intensity distribution that poses a problem according to the specifications. Similarly, as an evaluation criterion for cracking during molding, C is defined as no cracking can be confirmed, B is defined as some cracking can be confirmed but does not pose a problem according to the specifications, and A is defined as cracking that poses a problem according to the specifications. [Table 1]

[0073] In Examples 1 to 5, as shown in Table 1, the expansion of the light intensity distribution was suppressed. Therefore, it was found that the light intensity distribution can be suppressed when at least one surface of the lens 1 has a surface roughness greater than the surface roughness of the other parts in the portion where the thickness of the molded lens 1 is relatively thin.

[0074] Furthermore, in Examples 1 to 5, the occurrence of cracks was suppressed, as shown in Table 1. Therefore, it was found that the occurrence of cracks can be suppressed when at least one of the first member 2 and the second member 3 has a surface roughness greater than the surface roughness of the other parts in the part corresponding to the part where the thickness of the molded lens 1 is relatively thin.

[0075] Furthermore, in Examples 1 to 3, the occurrence of cracks was further suppressed. Therefore, it was found that in a configuration where at least one of the parts corresponding to the third part of the molded lens 1 is thicker than the first part and thinner than the second part, and has a surface roughness that is smaller than the surface roughness of the part corresponding to the first part and larger than the surface roughness of the part corresponding to the second part, the occurrence of cracks can be further suppressed.

[0076] Next, Examples 6 to 10 and Comparative Examples 6 to 10, in which the desired PSD was applied to the surface roughness of the mold 4, will be described.

[0077] (Example 6) In Example 6, a glass lens with a double-sided concave shape near the center was formed. A pair of molds 4 were prepared such that the thickness at the thickest point of the lens was 3.5 mm, the thickness at the thinnest point was 1.2 mm, and the thickness at any point selected from locations other than the thickest and thinnest points was 2.0 mm.

[0078] In this embodiment, surface roughening was applied to both the first member 2 and the second member 3 of the mold 4. Specifically, the mold surface was processed so that the spatial frequency of the extreme value of the PSD in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with the thickest point of the molded lens was 7584[1 / mm], the spatial frequency of the extreme value of the PSD in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with the thinnest point was 9505[1 / mm], and the spatial frequency of the extreme value of the PSD in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with an arbitrary point of selection was 8546[1 / mm].

[0079] Using this mold 4, molding was performed in the same manner as in Example 1. In this example, a glass lens without cracks was successfully molded. Furthermore, when the spatial frequencies of the PSD extrema at the thickest and thinnest points of the molded lens were measured, it was confirmed that the spatial frequency of the PSD extrema at the thinnest point was higher than that at the thickest point, and that there was no light intensity distribution. In addition, when a lens unit was fabricated using the molded lens and mounted on an information terminal, it was confirmed that good imaging performance was obtained.

[0080] (Example 7) In Example 7, a glass lens was formed with a concave shape on one side and a convex shape on the other near the center. A pair of molds 4 were prepared such that the thickness at the thickest point of the lens was 1.0 mm, the thickness at the thinnest point was 0.6 mm, and the thickness at any point selected from locations other than the thickest and thinnest points was 0.7 mm.

[0081] In this embodiment, surface roughening was applied to both the first member 2 and the second member 3 of the mold 4. Specifically, the mold surface was processed so that the spatial frequency of the PSD extreme value in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with the thickest point of the molded lens was 7986[1 / mm], the spatial frequency of the PSD extreme value in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with the thinnest point was 8765[1 / mm], and the spatial frequency of the PSD extreme value in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with an arbitrary selected point was 8454[1 / mm].

[0082] Using this mold 4, molding was performed in the same manner as in Example 1. In this example as well, crack-free glass lenses were formed. Furthermore, when the spatial frequencies of the PSD extrema at the thickest and thinnest points of the molded lens were measured, it was confirmed that the spatial frequency of the PSD extrema at the thinnest point was higher than the spatial frequency of the PSD extrema at the thickest point, and that the light intensity distribution was small.

[0083] (Example 8) In Example 8, a glass lens with a double-sided convex shape near the center was formed. A pair of molds 4 were prepared such that the thickness at the thickest point of the lens was 4.6 mm, the thickness at the thinnest point was 0.5 mm, and the thickness at any point selected from locations other than the thickest and thinnest points was 3.0 mm.

[0084] In this embodiment, surface roughening was applied only to the first component 2 of the mold 4. Specifically, the mold surface was processed so that the spatial frequency of the PSD extreme value in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with the thickest point of the molded lens was 6954[1 / mm], the spatial frequency of the PSD extreme value in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with the thinnest point was 7561[1 / mm], and the spatial frequency of the PSD extreme value in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with any selected point was 7254[1 / mm].

[0085] Using this mold 4, molding was performed in the same manner as in Example 1. In this example as well, molding without cracking was achieved. Furthermore, when the spatial frequencies of the PSD extrema at the thickest and thinnest points of the molded lens were measured, it was confirmed that the spatial frequency of the PSD extrema at the thinnest point was higher than the spatial frequency of the PSD extrema at the thickest point, and that there was no light intensity distribution.

[0086] (Example 9) In Example 9, a glass lens with a concave shape on one side and a convex shape on the other near the center was formed. A pair of molds 4 were prepared such that the thickness at the thickest point of the lens was 5.3 mm, the thickness at the thinnest point was 2.1 mm, and the thickness at any point selected from locations other than the thickest and thinnest points was 3.6 mm.

[0087] In this embodiment, surface roughening was applied only to the first component 2 of the mold 4. Specifically, the mold surface was processed so that the spatial frequency of the PSD extreme value in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with the thickest point of the molded lens was 6231[1 / mm], the spatial frequency of the PSD extreme value in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with the thinnest point was 6845[1 / mm], and the spatial frequency of the PSD extreme value in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with an arbitrary selected point was 6980[1 / mm].

[0088] Using this mold 4, molding was performed in the same manner as in Example 1. In this example, some cracking was observed, but the molding was completed at a level that was acceptable according to specifications. Furthermore, when the spatial frequencies of the PSD extrema at the thickest and thinnest points of the molded lens were measured, it was confirmed that the spatial frequency of the PSD extrema at the thinnest point was higher than the spatial frequency of the PSD extrema at the thickest point, and that there was no light intensity distribution.

[0089] (Example 10) In Example 10, a glass lens with a concave shape on one side and a convex shape on the other near the center was formed. A pair of molds 4 were prepared such that the thickness at the thickest point of the lens was 2.3 mm, the thickness at the thinnest point was 1.4 mm, and the thickness at any point selected from locations other than the thickest and thinnest points was 1.7 mm.

[0090] In this embodiment, surface roughening was applied only to the second component 3 of the mold 4. Specifically, the mold surface was processed so that the spatial frequency of the PSD extreme value in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with the thickest point of the molded lens was 8995[1 / mm], the spatial frequency of the PSD extreme value in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with the thinnest point was 9175[1 / mm], and the spatial frequency of the PSD extreme value in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with an arbitrary selected point was 8357[1 / mm].

[0091] Using this mold 4, molding was performed in the same manner as in Example 1. In this example as well, some cracks were observed, but the molding was performed at a level that was acceptable according to the specifications. Furthermore, when the spatial frequencies of the PSD extreme values ​​at the thickest and thinnest points of the molded lens were measured, it was confirmed that the spatial frequency of the PSD extreme value at the thinnest point was higher than the spatial frequency of the PSD extreme value at the thickest point, and that the light intensity distribution was small.

[0092] (Comparative Example 6) In Comparative Example 6, a glass lens with the same shape as in Example 6 was formed. In this Comparative Example, surface roughening was applied to both the first component 2 and the second component 3 of the mold 4. Specifically, the mold surface was processed so that the spatial frequency of the extreme value of the PSD in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with the thickest point of the formed lens was 9910[1 / mm], the spatial frequency of the extreme value of the PSD in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with the thinnest point was 7500[1 / mm], and the spatial frequency of the extreme value of the PSD in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point of contact with an arbitrary selected point was 6854[1 / mm].

[0093] Using this mold 4, molding was performed in the same manner as in Example 1. In this example as well, some cracks were observed, but the molding was completed at a level that did not pose a problem according to the specifications. Furthermore, when the spatial frequencies of the PSD extreme values ​​at the surface spatial frequencies of 6000 [1 / mm] to 10000 [1 / mm] at the thickest and thinnest points of the molded lens were measured, it was confirmed that the spatial frequency of the PSD extreme value at the thinnest point was higher than the spatial frequency of the PSD extreme value at the thickest point. However, the light intensity distribution was large, which was problematic according to the specifications.

[0094] (Comparative Example 7) In Comparative Example 7, a glass lens with the same shape as in Example 7 was formed. In this Comparative Example, surface roughness was applied to both the first member 2 and the second member 3 of the mold 4. Specifically, the mold surface was processed so that the spatial frequency of the extreme value of the PSD in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point in contact with the thickest point of the formed lens was 7423[1 / mm], the spatial frequency of the extreme value of the PSD in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point in contact with the thinnest point of the mold surface was 6156[1 / mm], and the spatial frequency of the extreme value of the PSD in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm] at the point in contact with an arbitrary point of selection was 6985[1 / mm].

[0095] Molding was performed using mold 4 in the same manner as in Example 1. In this comparative example, when mold 4 reached a temperature lower than the second temperature (580°C), the applied load was removed, but cracking occurred, and molding could not be completed. Because molding could not be completed, the light intensity distribution could not be measured.

[0096] (Comparative Example 8) In Comparative Example 8, a glass lens with the same shape as in Example 8 was formed. In this Comparative Example, only the first component 2 of the mold 4 was processed to impart surface roughness. Specifically, the processing was performed so that the spatial frequency of the extreme value of the PSD at the point of contact with the thickest point of the formed lens, in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm], was 6465[1 / mm], the spatial frequency of the extreme value of the PSD at the point of contact with the thinnest point, in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm], was 6065[1 / mm], and the spatial frequency of the extreme value of the PSD at the point of contact with an arbitrary selected point, in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm], was 6254[1 / mm].

[0097] Molding was performed using mold 4 in the same manner as in Example 1. In this comparative example, when mold 4 reached a temperature lower than the second temperature (580°C), the applied load was removed, but cracking occurred, and molding could not be completed. Because molding could not be completed, the light intensity distribution could not be measured.

[0098] (Comparative Example 9) In Comparative Example 9, a glass lens with the same shape as in Example 9 was formed. In this Comparative Example, only the first component 2 of the mold 4 was processed to impart surface roughness. Specifically, the processing was performed so that the spatial frequency of the extreme value of the PSD at the point of contact with the thickest point of the formed lens, in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm], was 8465[1 / mm], the spatial frequency of the extreme value of the PSD at the point of contact with the thinnest point, in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm], was 7454[1 / mm], and the spatial frequency of the extreme value of the PSD at the point of contact with an arbitrary selected point, in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm], was 8045[1 / mm].

[0099] Molding was performed using mold 4 in the same manner as in Example 1. In this comparative example, when mold 4 reached a temperature lower than the second temperature (580°C), the applied load was removed, but cracking occurred, and molding could not be completed. Because molding could not be completed, the light intensity distribution could not be measured.

[0100] (Comparative Example 10) In Comparative Example 10, a glass lens with the same shape as in Example 10 was formed. In this Comparative Example, only the second component 3 of the mold 4 was processed to impart surface roughness. Specifically, the processing was performed so that the spatial frequency of the extreme value of the PSD at the point of contact with the thickest point of the formed lens, in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm], was 6946[1 / mm], the spatial frequency of the extreme value of the PSD at the point of contact with the thinnest point, in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm], was 6656[1 / mm], and the spatial frequency of the extreme value of the PSD at the point of contact with an arbitrary selected point, in the spatial frequency range of 6000[1 / mm] to 10000[1 / mm], was 6257[1 / mm].

[0101] Molding was performed using mold 4 in the same manner as in Example 1. In this comparative example, when mold 4 reached a temperature lower than the second temperature (580°C), the applied load was removed, but cracking occurred, and molding could not be completed. Because molding could not be completed, the light intensity distribution could not be measured.

[0102] Table 2 below shows the glass lens shapes, surface roughness measurement results of mold 4, light intensity distribution of the lenses, and cracking results (degree of cracking) during molding for Examples 6 to 10 and Comparative Examples 6 to 10. The evaluation criteria for the light intensity distribution of the lenses are defined as follows: C for no light intensity distribution, B for some light intensity distribution that does not violate the standards, and A for light intensity distribution that violates the standards. Similarly, the evaluation criteria for cracking during molding are defined as follows: C for no cracking, B for some cracking that does not violate the standards, and A for cracking that violates the standards. [Table 2]

[0103] In Examples 6 to 10, the light intensity distribution was suppressed, as shown in Table 2. Therefore, it was found that the expansion of the light intensity distribution can be suppressed when at least one surface of the lens 1 has a surface roughness greater than the surface roughness of the other parts in the portion where the thickness of the molded lens 1 is relatively thin.

[0104] Furthermore, in Examples 6 to 10, the occurrence of cracks was suppressed, as shown in Table 2. Therefore, it was found that the occurrence of cracks can be suppressed when at least one of the first member 2 and the second member 3 has a surface roughness greater than the surface roughness of the other parts in the part corresponding to the part where the thickness of the molded lens 1 is relatively thin.

[0105] Furthermore, in Examples 6 to 8, the occurrence of cracks was further suppressed. Therefore, it was found that in a configuration where at least one of the parts corresponding to the third part of the molded lens 1 is thicker than the first part and thinner than the second part, and has a surface roughness that is smaller than the surface roughness of the part corresponding to the first part and larger than the surface roughness of the part corresponding to the second part, the occurrence of cracks can be further suppressed.

[0106] (Embodiment 2) Next, with reference to Figure 5, a lens unit according to Embodiment 2 of the present disclosure will be described. Figure 5 shows an example of a lens unit according to this embodiment. The lens unit 500 according to this embodiment is provided with a plurality of lenses 501, 502, 503 and a lens barrel 504. The lens barrel 504 holds the plurality of lenses 501, 502, 503. Here, the plurality of lenses 501, 502, 503 are constructed using the lenses described in Embodiment 1.

[0107] With this configuration, the lens unit is constructed using glass lenses that have a small light intensity distribution and suppress the occurrence of cracks during molding, thus enabling the stable production of lens units using high-precision glass lenses.

[0108] Furthermore, the lens unit only needs to include at least one of the lenses described in Embodiment 1, and the multiple lenses included in the lens unit may include other lenses. Also, the number of multiple lenses is not limited to three, and any number of lenses from two to three may be included in the lens unit.

[0109] (Embodiment 3) Next, an information terminal according to Embodiment 3 of the present disclosure will be described with reference to Figure 6. Figure 6 shows an example of an information terminal according to this embodiment. The information terminal according to this embodiment may be any known information terminal such as a mobile phone, smartphone, laptop PC (Personal Computer), or tablet terminal. The information terminal 600 according to this embodiment is provided with a lens 601 and an image sensor 602. Here, the lens 601 is configured using the lens described in Embodiment 1. The image sensor 602 can perform imaging through the lens 601.

[0110] With this configuration, the information terminal is constructed using lenses that have a small light intensity distribution and suppress the occurrence of cracks during molding, so that an information terminal with good imaging performance using high-precision lenses can be stably produced. The information terminal 600 may include two or more lenses as described in Embodiment 1. The information terminal 600 may also include the lens unit as described in Embodiment 2.

[0111] (Embodiment 4) Next, an imaging device according to Embodiment 4 of the present disclosure will be described with reference to Figure 7. Figure 7 shows an example of an imaging device according to this embodiment. Note that the imaging device according to this embodiment may be any known imaging device such as a digital camera or an analog camera. The imaging device 700 according to this embodiment is provided with a lens 701 and an image sensor 702. Here, the lens 701 is configured using the lens described in Embodiment 1. The image sensor 702 can perform imaging through the lens 701.

[0112] With this configuration, the imaging device is constructed using lenses that have a small light intensity distribution and suppress the occurrence of cracks during molding, so that an imaging device with good imaging performance using high-precision lenses can be stably produced. The imaging device may include two or more lenses as described in Embodiment 1. The imaging device 700 may also include the lens unit as described in Embodiment 2.

[0113] In Embodiments 1 to 4 described above, the lens according to this disclosure was a glass lens, but the material of the lens is not limited to glass. The lens according to this disclosure may be formed using, for example, plastic or any resin. Plastic lenses can be injection molded using a mold.

[0114] The above disclosure includes the following configuration and method: (Composition 1) A lens having a first optically effective surface and a second optically effective surface intersecting the optical axis, At least one of the first optical effective surface and the second optical effective surface has an inflection point when viewed from the intersection with the optical axis toward the edge of the effective region. The thickness distribution between the first optical effective surface and the second optical effective surface in a direction parallel to the optical axis has an extremum at a position away from the optical axis in a direction perpendicular to the optical axis. At least one of the first optical effective surface and the second optical effective surface has a surface roughness greater than the surface roughness of the second portion which is thicker than the first portion, in the first portion of the lens. A lens characterized in that the difference between the surface roughness of the first portion and the surface roughness of the second portion is 1.0 nmRa or greater in terms of arithmetic mean roughness. (Configuration 2) The lens according to configuration 1, characterized in that the difference between the surface roughness of the first portion and the surface roughness of the second portion is 10 nmRa or less in terms of arithmetic mean roughness. (Composition 3) The lens according to configuration 1 or 2, characterized in that at least one of the first optical effective surface and the second optical effective surface of the lens has a third portion which is thicker than the first portion of the lens and thinner than the second portion, and in this third portion, the surface roughness is less than that of the first portion and greater than that of the second portion. (Composition 4) The lens according to any one of configurations 1 to 3, characterized in that at least one of the first optical effective surface and the second optical effective surface of the lens has a surface roughness greater than the surface roughness of the point with maximum thickness in the point group, at the point where the thickness is minimum, which includes the point corresponding to the intersection of the optical axis in the thickness distribution of the lens, the point corresponding to the edge of the effective region of the lens, and the point having an extremum. (Composition 5) The lens according to configuration 4, characterized in that at least one of the first optical effective surface and the second optical effective surface of the lens has a surface roughness at a point far from the point in the point group where the thickness is minimum and the point where the thickness is maximum, that is less than the surface roughness of the point where the thickness is minimum and greater than the surface roughness of the point where the thickness is maximum. (Composition 6) The lens according to any one of configurations 1 to 5, characterized in that the surface roughness of at least one of the first optical effective surface and the second optical effective surface of the lens changes in steps or continuously. (Composition 7) The lens according to any one of configurations 1 to 6, characterized in that the surface roughness of at least one of the first optical effective surface and the second optical effective surface of the lens is provided in proportion to the thickness of the lens. (Composition 8) The lens according to configuration 7, characterized in that at least one of the first optical effective surface and the second optical effective surface of the lens has a surface roughness such that the surface roughness of the portion of the lens increases as the thickness of the lens decreases. (Composition 9) The lens according to any one of configurations 1 to 8, characterized in that at least one of the first optical effective surface and the second optical effective surface of the lens is given surface roughness by at least one of laser processing, polishing, ion beam processing, and blasting. (Composition 10) The lens according to any one of configurations 1 to 9, characterized in that the surface roughness of the first portion and the second portion of at least one of the first and second optical effective surfaces of the lens is 2 nmRa to 12 nmRa in terms of arithmetic mean roughness. (Composition 11) The lens according to any one of configurations 1 to 9, characterized in that the surface roughness of the first portion and the second portion of at least one of the first and second optical effective surfaces of the lens is such that, in the spatial frequency range of 6000 [1 / mm] to 10000 [1 / mm] expressed by power spectral density, the spatial frequency at which the power spectral density of the first portion reaches an extreme value is higher than the spatial frequency at which the power spectral density of the second portion reaches an extreme value. (Composition 12) The lens according to any one of configurations 1 to 9, characterized in that the difference between the maximum and minimum thickness of the lens is 0.4 mm to 5.0 mm. (Composition 13) A pair of first and second members used for press-forming a lens having a first optical effective surface and a second optical effective surface intersecting the optical axis, at least one of the first optical effective surface and the second optical effective surface having an inflection point when moving from the intersection with the optical axis toward the edge of the effective region, and the thickness distribution between the first optical effective surface and the second optical effective surface in a direction parallel to the optical axis having an extremum at a position away from the optical axis in a direction perpendicular to the optical axis, A molding die characterized in that at least one of the first member and the second member has a surface roughness greater than that of the second corresponding member, which is thicker than the first part of the lens, in the first corresponding part corresponding to the first part of the lens. (Composition 14) The molding die according to configuration 13, characterized in that the difference between the surface roughness of the first corresponding portion and the surface roughness of the second corresponding portion is 1.0 nmRa or more and 10 nmRa or less in terms of arithmetic mean roughness. (Composition 15) The molding die according to configuration 13 or 14, characterized in that the surface roughness of the first corresponding portion and the second corresponding portion is 2 nmRa to 12 nmRa in terms of arithmetic mean roughness. (Composition 16) The molding die according to configuration 13 or 14, characterized in that the surface roughness of the first corresponding portion and the second corresponding portion of at least one of the first member and the second member is such that, in the spatial frequency range of 6000 [1 / mm] to 10000 [1 / mm] expressed by power spectral density, the spatial frequency at which the power spectral density of the first corresponding portion reaches an extreme value is higher than the spatial frequency at which the power spectral density of the second corresponding portion reaches an extreme value. (Composition 17) A lens as described in any of configurations 1 to 12, A lens barrel that holds multiple lenses, including the aforementioned lens, A lens unit characterized by having the following features. (Composition 18) A lens as described in any of configurations 1 to 12, An image sensor that performs imaging through the aforementioned lens, An information terminal characterized by being equipped with the following features. (Composition 19) A lens as described in any of configurations 1 to 12, An image sensor that performs imaging through the aforementioned lens, An imaging device characterized by comprising: (Method 1) A molding method for press-forming a lens having a first optically effective surface and a second optically effective surface intersecting the optical axis, The lens is press-molded using a molding die, wherein at least one of the first optical effective surface and the second optical effective surface has an inflection point when moving from the intersection with the optical axis toward the edge of the effective area, the thickness distribution between the first optical effective surface and the second optical effective surface in a direction parallel to the optical axis has an extremum at a position away from the optical axis in a direction perpendicular to the optical axis, and at least one of the first optical effective surface and the second optical effective surface has a surface roughness in the first portion of the lens that is greater than the surface roughness of the second portion which is thicker than the first portion. A molding method characterized in that the difference between the surface roughness of the first portion and the surface roughness of the second portion is 1.0 nmRa or more in terms of arithmetic mean roughness.

[0115] The present disclosure has been described above with reference to the embodiments and examples, but the present disclosure is not limited to the embodiments and examples described above. Inventions modified to the extent that they do not contradict the spirit of the present disclosure, and inventions equivalent to the present disclosure are also included in the present disclosure. Furthermore, the embodiments and examples described above can be combined as appropriate to the extent that they do not contradict the spirit of the present disclosure. [Explanation of symbols]

[0116] 1: Lens, 2: First component, 3: Second component, 4: Mold, 110, 310: Thickness distribution of the lens

Claims

1. A lens having a first optically effective surface and a second optically effective surface intersecting the optical axis, At least one of the first optical effective surface and the second optical effective surface has an inflection point when viewed from the intersection with the optical axis toward the edge of the effective region. The thickness distribution between the first optical effective surface and the second optical effective surface in a direction parallel to the optical axis has an extremum at a position away from the optical axis in a direction perpendicular to the optical axis. At least one of the first optical effective surface and the second optical effective surface has a surface roughness greater than the surface roughness of the second portion which is thicker than the first portion, in the first portion of the lens. A lens characterized in that the difference between the surface roughness of the first portion and the surface roughness of the second portion is 1.0 nmRa or greater in terms of arithmetic mean roughness.

2. The lens according to claim 1, characterized in that the difference between the surface roughness of the first portion and the surface roughness of the second portion is 10 nmRa or less in terms of arithmetic mean roughness.

3. The lens according to claim 1, characterized in that at least one of the first optical effective surface and the second optical effective surface of the lens has a third portion which is thicker than the first portion of the lens and thinner than the second portion, and in which the third portion has a surface roughness that is less than the surface roughness of the first portion and greater than the surface roughness of the second portion.

4. The lens according to claim 1, wherein at least one of the first optical effective surface and the second optical effective surface of the lens has a surface roughness greater than the surface roughness of the point with maximum thickness in the point group, at the point where the thickness is minimum, which includes the point corresponding to the intersection of the optical axis in the thickness distribution of the lens, the point corresponding to the edge of the effective region of the lens, and the point having an extremum.

5. The lens according to claim 4, characterized in that at least one of the first optical effective surface and the second optical effective surface of the lens has a surface roughness at a point far from the point in the point group where the thickness is minimum and the point where the thickness is maximum, that is less than the surface roughness of the point where the thickness is minimum and greater than the surface roughness of the point where the thickness is maximum.

6. The lens according to claim 1, characterized in that the surface roughness of at least one of the first optical effective surface and the second optical effective surface of the lens changes in steps or continuously.

7. The lens according to claim 1, characterized in that the surface roughness of at least one of the first optical effective surface and the second optical effective surface of the lens is provided in proportion to the thickness of the lens.

8. The lens according to claim 7, characterized in that at least one of the first optical effective surface and the second optical effective surface of the lens has a surface roughness such that the surface roughness of the portion of the lens increases as the thickness of the lens decreases.

9. The lens according to claim 1, characterized in that at least one of the first optical effective surface and the second optical effective surface of the lens is given surface roughness by at least one of laser processing, polishing, ion beam processing, and blasting.

10. The lens according to claim 1, characterized in that the surface roughness of at least one of the first and second optical effective surfaces of the lens is 2 nmRa to 12 nmRa in terms of arithmetic mean roughness.

11. The lens according to claim 1, characterized in that the surface roughness of the first portion and the second portion of at least one of the first and second optical effective surfaces of the lens is such that, in the spatial frequency range of 6000 [1 / mm] to 10000 [1 / mm] expressed by power spectral density, the spatial frequency at which the power spectral density of the first portion reaches an extreme value is higher than the spatial frequency at which the power spectral density of the second portion reaches an extreme value.

12. The lens according to claim 1, characterized in that the difference between the maximum and minimum thickness of the lens is 0.4 mm to 5.0 mm.

13. A lens having a first optical effective surface and a second optical effective surface intersecting the optical axis, wherein at least one of the first optical effective surface and the second optical effective surface has an inflection point when moving from the intersection with the optical axis toward the edge of the effective region, and the thickness distribution between the first optical effective surface and the second optical effective surface in a direction parallel to the optical axis has an extremum at a position away from the optical axis in a direction perpendicular to the optical axis, comprising a pair of first and second members used for press-forming the lens, A molding die characterized in that at least one of the first member and the second member has a surface roughness greater than that of the second corresponding member, which is thicker than the first part of the lens, in the first corresponding part corresponding to the first part of the lens.

14. The molding die according to claim 13, characterized in that the difference between the surface roughness of the first corresponding portion and the surface roughness of the second corresponding portion is 1.0 nmRa or more and 10 nmRa or less in terms of arithmetic mean roughness.

15. The molding die according to claim 13, characterized in that the surface roughness of the first corresponding portion and the second corresponding portion is 2 nmRa to 12 nmRa in terms of arithmetic mean roughness.

16. The molding die according to claim 13, wherein the surface roughness of the first corresponding portion and the second corresponding portion of at least one of the first member and the second member is such that, in the spatial frequency range of 6000 [1 / mm] to 10000 [1 / mm] expressed by power spectral density, the spatial frequency at which the power spectral density of the first corresponding portion reaches an extreme value is higher than the spatial frequency at which the power spectral density of the second corresponding portion reaches an extreme value.

17. A lens according to any one of claims 1 to 12, A lens barrel that holds multiple lenses, including the aforementioned lens, A lens unit characterized by having the following features.

18. A lens according to any one of claims 1 to 12, An image sensor that performs imaging through the aforementioned lens, An information terminal characterized by being equipped with the following features.

19. A lens according to any one of claims 1 to 12, An image sensor that performs imaging through the aforementioned lens, An imaging device characterized by comprising:

20. A molding method for press-forming a lens having a first optically effective surface and a second optically effective surface intersecting the optical axis, The lens is press-molded using a molding die, wherein at least one of the first optical effective surface and the second optical effective surface has an inflection point when moving from the intersection with the optical axis toward the edge of the effective area, the thickness distribution between the first optical effective surface and the second optical effective surface in a direction parallel to the optical axis has an extremum at a position away from the optical axis in a direction perpendicular to the optical axis, and at least one of the first optical effective surface and the second optical effective surface has a surface roughness in the first portion of the lens that is greater than the surface roughness of the second portion which is thicker than the first portion. A molding method characterized in that the difference between the surface roughness of the first portion and the surface roughness of the second portion is 1.0 nmRa or more in terms of arithmetic mean roughness.

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