Lens with barrel

Abstract

To provide a lens that can be integrated with a barrel with excellent airtightness, the lens allowing suppression of the occurrence of reflected light or scattered light inside of the lens, without having to provide additional processing steps such as black-painting and blackening.SOLUTION: A lens comprises a barrel made of metal, a lens part made of glass and provided inside of the barrel, and a light absorption part made of glass and provided between the inner circumference of the barrel and the outer edge of the lens part in the radial direction of the barrel. A first temperature region from the yield point to the softening point of a first glass material constituting the lens part and a second temperature region from the yield point to the softening point of a second glass material constituting the light absorption part have an overlapping temperature region.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lens with a lens barrel in which a lens portion is provided inside the lens barrel. [Background technology]

[0002] In the fixing structure of the optical lens described in Patent Document 1, a circular hole for accommodating the lens is opened in the holder, an annular groove is formed in the inward flange of this circular hole, and the entrance or exit surface of the optical lens is bonded via an adhesive provided in this groove. This aims to realize a fixing structure that does not generate stress in the optical lens that causes wavefront aberration in a structure in which the optical lens is fixed to the holder with an adhesive. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 3-271707 Summary of the Invention [Problem to be solved by the invention]

[0004] In camera lenses and the like, it is undesirable for reflected light or scattered light to occur inside the lens, and in order to prevent reflected light or scattered light, some lenses have their sides painted black or have their sides blackened. In addition, when it is necessary to suppress the incidence of light from outside the effective diameter of the lens, some lenses also have a blackened coating applied to the area outside the effective diameter. Blackening or blackening is performed by painting, vapor deposition, plating, or the like.

[0005] However, in order to apply a black coating or blackening treatment to a lens, a processing step for the black coating or blackening is required in addition to the lens molding in the lens manufacturing process. When such a processing step is introduced, problems arise such as the lens manufacturing process becoming more complicated and the introduction cost of the equipment for the processing step becoming higher.

[0006] Furthermore, when a lens that has been painted black or blackened is placed inside a lens barrel, it needs to be placed inside the lens barrel in an airtight manner to prevent the generation of new reflected light or scattered light. However, to place the lens in an airtight manner without damaging the layer formed by the painting or blackening, a high level of precision is required in the manufacturing process.

[0007] Therefore, an object of the present invention is to provide a lens with a lens barrel that can suppress the generation of reflected light and scattered light inside the lens without the need for additional processing steps such as black painting or blackening, and that can be integrated with the lens barrel with good airtightness. [Means for solving the problem]

[0008] In order to solve the above problems, the lens with a lens barrel of the present invention comprises a metal lens barrel, a glass lens portion provided within the lens barrel, and a glass light absorbing portion provided in the radial direction of the lens barrel between the inner surface of the lens barrel and the outer edge of the lens portion, and is characterized in that a first temperature range from the yield point to the softening point of a first glass material constituting the lens portion and a second temperature range from the yield point to the softening point of a second glass material constituting the light absorbing portion have overlapping temperature ranges.

[0009] This allows the shape of the light absorbing part to be processed when the lens surface of the lens part is molded, and the lens part can be positioned relative to the lens barrel via the light absorbing part. This makes it possible to obtain a lens with a lens barrel in which the lens surface is positioned with high accuracy relative to the lens barrel and the lens barrel, light absorbing part, and lens part are integrated with good airtightness. It also makes it possible to suppress the occurrence of reflected light and scattered light inside the lens barrel without providing additional processing steps such as black painting or blackening.

[0010] In the barrel-mounted lens of the present invention, the overlapping temperature range is preferably 10° C. or higher. This prevents the lens portion and the light absorbing portion from going outside the processable temperature range during molding, making it possible to perform molding with high positional accuracy.

[0011] In the lens with a lens barrel of the present invention, the first glass transition point of the first glass material is preferably higher than the second glass transition point of the second glass material. As a result, even after the first glass material is cooled below the glass transition point and the lens portion is formed during the cooling process after molding, the end face of the light absorbing portion continues to undergo plastic deformation following the molding surface of the mold and the outer edge of the lens portion, so that high shape transferability can be achieved. For example, when a spherical or cubic first glass material similar to a sphere is placed in a circular second glass material and molded, the shape of the peripheral edge of the lens portion is easily formed, and the adhesion between the lens portion and the light absorbing portion can be improved. In contrast, in a method of forming a lens by heating and cooling soft glass at a low temperature, the position of the lens surface cannot be controlled when fixing the lens, so problems such as optical axis deviation are likely to occur, especially when forming an aspherical lens.

[0012] In the lens with a lens barrel of the present invention, the difference in refractive index between the first glass material and the second glass material is preferably within ±2.5%. This suppresses the reflection of light at the boundary between the lens section and the light absorbing section, making it easier for light traveling from the lens section to enter the light absorbing section, and light is appropriately absorbed within the light absorbing section. This suppresses the reflection of light at the boundary and ensures that light that can be absorbed by the light absorbing section is absorbed, making it possible to suppress the generation of stray light and harmful light that returns to the lens section.

[0013] In the lens with a lens barrel of the present invention, the lens portion preferably has a lens surface that exerts a predetermined refractive effect on at least one of the end faces of the lens portion in the optical axis direction. This makes it possible to provide a lens portion in which the optical path can be controlled by the lens surface without controlling the optical path by a concentration gradient inside the lens portion or in addition to the above-mentioned concentration control.

[0014] In the lens with a lens barrel of the present invention, it is preferable that a surface made of a second glass material is located between the lens surface and the lens barrel so as to be continuous with the lens surface. This makes it possible to mold the lens portion made of the first glass material and the light absorbing portion made of the second glass material at the same time.

[0015] In the lens with a lens barrel of the present invention, the lens portion comprises a central portion having a lens surface, and a peripheral portion provided on the outer edge of the central portion in the radial direction of the lens portion, and it is preferable that the ratio of the thickness of the light absorbing portion in the optical axis direction to the thickness of the peripheral portion is 0.8 or more. This makes it possible to mold the light absorbing portion made of the second glass material at the same time as molding the lens portion made of the first glass material, and also ensure the adhesive strength between the lens barrel.

[0016] In the barrel-mounted lens of the present invention, the second glass material preferably has a light absorption band that is not present in the first glass material. This allows light having a wavelength in the light absorption band out of the light incident on the lens portion to be absorbed by the light absorbing portion, thereby making it possible to suppress the generation of stray light. Effect of the Invention

[0017] According to the present invention, it is possible to provide a lens with a lens barrel that can suppress the generation of reflected light and scattered light inside the lens barrel without the need for any additional processing steps, and that can be integrated with the lens barrel in an airtight manner. [Brief description of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view showing a configuration of a lens with a lens barrel according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing a configuration of a molding die according to an embodiment of the present invention. [Diagram 3] 3 is a cross-sectional view showing a process of introducing raw materials for a lens barrel and a lens portion and raw materials for a light absorbing portion into the lower mold shown in FIG. 2. [Figure 4] 3 is a cross-sectional view showing a process of introducing raw materials for the lens barrel and the lens portion and raw materials for the light absorbing portion into the lower mold shown in FIG. 2, and then molding the same with an upper mold. FIG. [Diagram 5]1 is a side view showing a configuration used for measuring the reflectance of a configuration corresponding to a barrel, a lens portion, and a light absorbing portion of a barrel-equipped lens. FIG. [Figure 6] 6 is a graph showing the change in reflectance versus wavelength of measurement light in the configurations shown in FIGS. 5(a), (b), and (c), and the change in reflectance of a simulated value. [Figure 7] 1 is a graph showing the change in reflectance of light reflected from the bonded surface with respect to the change in the angle of incidence on the surface of a sample when measurement light is incident on the surface of the sample made of two glass plates with different refractive indices bonded together. [Figure 8] 1 is a graph showing the change in reflectance of light reflected from the bonded surface with respect to the change in the angle of incidence on the surface of a sample when measurement light is incident on the surface of the sample made of two glass plates with different refractive indices bonded together. [Figure 9] 1 is a graph showing the change in reflectance of light reflected from the bonded surface with respect to the change in the angle of incidence on the surface of a sample when measurement light is incident on the surface of the sample made of two glass plates with different refractive indices bonded together. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] <Configuration of lens with barrel> The configuration of the lens with a lens barrel according to the embodiment of the present invention will be described in detail with reference to Fig. 1(a) and Fig. 1(b). Fig. 1(a) shows an example of a lens with a lens barrel 10 in which the lens portion 30 is a biconvex lens, and Fig. 1(b) shows an example of a lens with a lens barrel 110 in which the lens portion 130 is a plano-concave lens. Fig. 1(a) and Fig. 1(b) are cross-sectional views taken along the optical axis AX of the lens portions 30 and 130. The lens portion of the lens with a lens barrel may be a lens having a shape other than that shown in Fig. 1(a) and Fig. 1(b), for example, a plano-convex lens or a biconcave lens, as long as it has a lens surface that exerts a predetermined refractive effect on at least one of the end faces of the lens portion in the optical axis direction.

[0020] 1(a) includes a lens barrel 20, a lens section 30 arranged inside the lens barrel 20, and a light absorbing section 40 arranged between the lens barrel 20 and the lens section 30 in the radial direction of the lens barrel 20. A lens barrel 110 shown in FIG. 1(b) has a similar configuration and includes a lens barrel 120, a lens section 130 arranged inside the lens barrel 120, and a light absorbing section 140 arranged between the lens barrel 120 and the lens section 130 in the radial direction of the lens barrel 120.

[0021] <Telescope tubes 20 and 120> The lens barrels 20 and 120 are hollow cylindrical metal objects manufactured by molding a metal material. The metal material constituting the lens barrels 20 and 120 has a higher melting point than the softening point of the glass material used in the lens sections 30 and 130 and the light absorbing sections 40 and 140, and may be, for example, stainless steel.

[0022] <Lens section 30> The lens unit 30 shown in FIG. 1(a) is made of glass and is disposed within the lens barrel 20 so as to share the optical axis AX with the lens barrel 20. The lens unit 30 has two lens surfaces 31, 32 that exert a predetermined refractive effect on both end faces in the direction of the optical axis AX. Each of the two lens surfaces 31, 32 forms a convex surface that protrudes outward in the direction of the optical axis AX. This makes the lens unit 30 a biconvex lens. The two lens surfaces 31, 32 may be either spherical or aspherical. Here, in the direction of the optical axis AX, the first lens surface 31 side of the lens portion 30 may be referred to as the upper side, and the second lens surface 32 side as the lower side.

[0023] The lens portion 30 has a shape that is rotationally symmetrical about the optical axis AX, and has a central portion A1 having two lens surfaces 31, 32 in the radial direction about the optical axis AX, and a peripheral portion A2 provided on the outer edge of the central portion A1. The peripheral portion A2 has an outer edge portion 30a as an outer circumferential surface that faces the inner circumferential surface 20a of the lens barrel 20. The peripheral portion A2 has a constant thickness D3 in the direction of the optical axis AX.

[0024] <Lens section 130> The lens unit 130 shown in FIG. 1(b) is made of glass, and is disposed within the lens barrel 120 so as to share the optical axis AX with the lens barrel 120. The lens unit 130 has a lens surface 131 that exerts a predetermined refractive effect on one end face in the direction of the optical axis AX. The other end face of the lens unit 130 is a flat surface 132. The lens surface 131 forms a concave surface that is recessed inward in the direction of the optical axis AX. This causes the lens unit 130 to form a plano-concave lens. The lens surface 131 may be either a spherical surface or an aspherical surface.

[0025] The lens portion 130 has a shape that is rotationally symmetrical about the optical axis AX, and has, in the radial direction about the optical axis AX, a central portion A11 having a lens surface 131, and a peripheral portion A12 provided on the outer edge of the central portion A11. The peripheral portion A12 has an outer edge portion 130a as an outer circumferential surface that faces the inner circumferential surface 120a of the lens barrel 120. The thickness of the peripheral portion A12 in the direction of the optical axis AX increases with increasing distance from the optical axis AX, and has a maximum thickness D13 at the outer edge portion 130a.

[0026] <Light absorbing portion 40> The light absorbing portion 40 shown in FIG. 1(a) is made of glass and is provided between the inner peripheral surface 20a of the lens barrel 20 and the outer peripheral portion 30a of the lens portion 30. The light absorbing portion 40 has a constant thickness D4 in the direction of the optical axis AX. The thickness D4 of the light absorbing portion 40 is the same as the thickness D3 of the peripheral portion A2 of the lens portion 30. The upper end face 41 of the light absorbing portion 40 is flush with the upper end face 33 of the peripheral portion A2 and is continuous with the lens surface 31 between the lens surface 31 and the inner peripheral surface 20a of the lens barrel 20.

[0027] <Light absorbing portion 140> 1(b) is made of glass and is provided between an inner peripheral surface 120a of the barrel 120 and an outer peripheral portion 130a of the lens portion 130. The thickness of the light absorbing portion 140 in the direction of the optical axis AX increases with increasing distance from the optical axis AX, and has a maximum thickness D14 at the inner peripheral surface 120a of the barrel 120. An upper end face 141 of the light absorbing portion 140 forms a curved surface that is continuous with an upper end face 133 of the peripheral portion A12, and is continuous with the lens surface 131 between the lens surface 131 and the inner peripheral surface 120a of the barrel 120.

[0028] <Glass materials> The first glass material constituting the lens portions 30 and 130 has a glass transition point, a yield point, and a softening point, and has a first temperature range from the yield point to the softening point.

[0029] The second glass material constituting the light absorbing portions 40 and 140 also has a glass transition point, a yield point, and a softening point, and has a second temperature range as the temperature range from the yield point to the softening point.

[0030] The first temperature range of the first glass material and the second temperature range of the second glass material have mutually overlapping temperature ranges. This overlapping temperature range is preferably 10°C or more. Since they have such overlapping temperature ranges, it is possible to simultaneously mold both the raw material 30m of the lens section 30 and the raw material 40m of the light absorbing section 40 in the lens barrel 20 (see FIG. 4). This makes it possible to accurately position the lens section 30 relative to the lens barrel 20 via the light absorbing section 40, and it is possible to obtain a lens with a lens barrel 10 with high positioning accuracy of the lens surface 31 relative to the lens barrel 20. This is also true for the lens section 130 shown in FIG. 1(b). In the following, the lens with a lens barrel 10 shown in FIG. 1(a) will be described as an example, but the same is true for the lens with a lens barrel 110 shown in FIG. 1(b) unless otherwise stated. From the viewpoint of making it easier to obtain a lens 10 with a lens barrel 20 having high positioning accuracy of the lens surface 31 relative to the lens barrel 20, the above-mentioned overlap temperature range is preferably 20°C or higher, and particularly preferably 50°C or higher.

[0031] On the other hand, when the overlapping temperature range is less than 10°C, the difference between the moldable temperature ranges of the first glass material and the second glass material becomes large, and therefore it is not easy to simultaneously mold the raw material 30m of the lens portion 30 and the raw material 40m of the light absorbing portion 40 placed in the lens barrel 20. Therefore, the above process makes it more difficult to position the lens portion 30 relative to the lens barrel 20 via the light absorbing portion 40.

[0032] If a material having a first glass transition point higher than a second glass transition point of the second glass material is selected as the first glass material used for the lens portion 30, then when the first glass material is disposed inside the second glass material and molded, the inner surface shape of the light absorbing portion 40 is formed along the outer edge portion 30a of the peripheral portion A2 of the lens portion 30, and therefore it is possible to improve adhesion between the lens portion 30 and the light absorbing portion 40.

[0033] Furthermore, since the second glass material is relatively easier to deform than the first glass material, in the cooling process, the first glass material becomes equal to or lower than the glass transition point, and the lens portion 30 is molded following the first optical surface 51c of the upper mold 51, but the end surface 41 of the light absorbing portion 40 continues to undergo plastic deformation following the lower surface 51b (molding surface) of the upper mold 51. Also, the inner peripheral surface 42 of the light absorbing portion 40 continues to undergo plastic deformation following the shape of the outer edge portion 30a of the lens portion 30. Therefore, the shape transferability can be improved.

[0034] In contrast, when using soft glass such as soda-lime glass and performing a process of heating and cooling at low temperatures, the position of lens surface 31 cannot be controlled when fixing lens portion 30 to lens barrel 20, and problems such as optical axis misalignment are likely to occur, particularly in the case of aspheric lenses.

[0035] The difference in refractive index between the first glass material and the second glass material is preferably within ±2.5%. By making the difference in refractive index within ±2.5%, it is possible to suppress the reflection of light at the boundary between the lens section 30 and the light absorbing section 40, and in particular, it is possible to suppress the generation of stray light in which light traveling from the lens section 30 side toward the light absorbing section 40 side is reflected at the boundary and returns to the inside of the lens section 30, and it is possible to reliably absorb light traveling toward the light absorbing section 40 side within the light absorbing section 40. From the viewpoint of enjoying such optical effects more stably, it is preferable that the difference in refractive index is within ±1.5%, and particularly preferably within ±0.5%.

[0036] As described above, the light absorbing portion 40 is disposed between the inner peripheral surface 20a of the lens barrel 20 and the outer peripheral portion 30a of the lens portion 30, and the raw material 30m of the lens portion 30 and the raw material 40m of the light absorbing portion 40 are disposed in the lens barrel 20 and integrally molded, thereby forming a predetermined shape having an end surface 41 continuous with the lens surface 31 of the lens portion 30. This shape can prevent stray light that is harmful to the image formation by the lens portion 30 from returning to the lens portion 30, such as when light traveling from the lens portion 30 side toward the light absorbing portion 40 is reflected at the boundary, or when light incident on the light absorbing portion 40 is reflected at the inner peripheral surface 20a of the lens barrel 20. In addition, unlike conventional lenses with a lens barrel, there is no need to perform additional processing such as blackening treatment on the lens before assembling it to a holding member such as a lens barrel.

[0037] As shown in FIG. 1(a), in the direction along the optical axis AX, the thickness D3 of the peripheral portion A2 of the lens portion 30 is constant, and the thickness D4 of the light absorbing portion 40 is also constant; the thickness D3 of the peripheral portion A2 and the thickness D4 of the light absorbing portion 40 are the same, and the end face 33 and the end face 41 form the same plane.

[0038] 1(b), the peripheral portion A12 of the lens portion 130 becomes thicker in the direction along the optical axis AX as it approaches the lens barrel 120, and has a maximum thickness D13 at the boundary with the light absorbing portion 140. The light absorbing portion 140 also becomes thicker in the direction along the optical axis AX as it approaches the lens barrel 120, and has a maximum thickness D14 at the boundary with the inner circumferential surface 120a of the lens barrel 120. The maximum thickness D14 of the light absorbing portion 140 is larger than the maximum thickness D13 of the peripheral portion A12 of the lens portion 130.

[0039] The relationship between the thickness of the peripheral portion of the lens portion and the thickness of the light absorbing portion is not limited to the relationship shown in Fig. 1(a) and Fig. 1(b), but it is preferable that the ratio of the thickness of the light absorbing portion in the direction of the optical axis AX to the thickness of the peripheral portion of the lens portion is 0.8 or more. This allows the lens 10 with a lens barrel of Fig. 1(a) to ensure sufficient mutual fixing strength between the lens portion 30 and the light absorbing portion 40. In addition, the light traveling from the center portion A1 of the lens portion 30 to the peripheral portion A2 can be reliably absorbed by the light absorbing portion 40, and the lens portion 30 can form an image while suppressing stray light. These effects are similar to those of the lens 110 with a lens barrel shown in Fig. 1(b).

[0040] The second glass material of the light absorbing section 40 has a light absorption band that is not present in the first glass material of the lens section 30. For example, when the second glass material has a light absorption band capable of absorbing light in a region with a longer wavelength than visible light, it becomes possible to cause the light absorbing section 40 to absorb light with a longer wavelength than visible light among the light incident on the lens section 30, and form an image with light with a reduced amount of light in this wavelength region.

[0041] The first glass material and the second glass material may have light absorption bands capable of absorbing light in different wavelength ranges. For example, if the first glass material absorbs ultraviolet light and the second glass material absorbs infrared light, the lens section 30 can form an image with light in which the ultraviolet and infrared light are reduced.

[0042] <Manufacturing process for lenses with barrels> Next, a description will be given of a manufacturing process of the lens with a lens barrel 10. The lens with a lens barrel 10 is manufactured using a molding die 50 having an upper die 51 and a lower die 52, as shown in FIG.

[0043] The upper mold 51 has a mold material 51a that is approximately disk-shaped overall, and this mold material 51a has a first optical surface 51c, which is a concave curved surface, at the center of a lower surface 51b that faces the lower mold 52, corresponding to the first lens surface 31 of the lens portion 30.

[0044] The lower mold 52 has a bottom wall portion 52a that is approximately circular plate-shaped overall, and the bottom wall portion 52a has an upper surface 52b that faces the lower surface 51b of the upper mold 51, and at the center of the upper surface 52b, an optical surface 52c that is a concave curved surface corresponding to the second lens surface 32 of the lens portion 30.

[0045] In bottom wall portion 52a, an annular recess 52d is provided along the outer periphery of upper surface 52b thereof, recessed downward. Furthermore, on the outer periphery of bottom wall portion 52a, a side wall portion 52e extends upward, i.e., toward upper mold 51, in the shape of a hollow cylinder. Side wall portion 52e is connected to annular recess 52d, and its inner circumferential surface 52f has an inner diameter corresponding to outer circumferential surface 20b of lens barrel 20.

[0046] 3 or 4, the lens barrel 20, raw material 30m of the lens portion 30, and raw material 40m of the light absorbing portion 40 are introduced into the lower mold 52. The lens barrel 20 is inserted into the lower mold 52 while the outer circumferential surface 20b is slid along the inner circumferential surface 52f, and the outer circumferential portion of the bottom surface 21 is placed in the annular recess 52d of the lower mold 52.

[0047] A hollow cylindrical raw material 40m of the light absorbing portion 40 is disposed inside the lens barrel 20, and a spherical or spherical three-dimensional raw material 30m of the lens portion 30 is disposed inside the raw material 40m. The raw material 30m is disposed such that a center portion 31m of the bottom is positioned on the second optical surface 52c of the lower mold 52 (see FIG. 4).

[0048] In the state shown in FIG. 4 , while applying a temperature in the overlapping temperature range from the yield point to the softening point of the first glass material and the temperature range from the yield point to the softening point of the second glass material, the upper die 51 is lowered to apply pressure to the raw materials 30m, 40m in the lower die 52, whereby the raw materials 30m, 40m are plastically deformed and the lens portion 30 and the light absorbing portion 40 are formed simultaneously.

[0049] As described above, the first glass material and the second glass material have an overlapping temperature range of 10°C or more in the temperature range from the yield point to the softening point. Therefore, when the lens surfaces 31 and 32 are molded on the lens unit 30 by the first optical surface 51c of the upper mold 51 and the second optical surface 52c of the lower mold 52, the shape of the light absorbing portion 40 can also be processed, and the lens unit 30 can be positioned relative to the lens barrel 20 via the light absorbing portion 40. Therefore, a lens with a lens barrel having high positioning accuracy of the lens surfaces 31 and 32 relative to the lens barrel 20 can be obtained. In addition, since there is no need to perform additional processing such as blackening treatment to provide a light absorbing function as in the conventional lens, the manufacturing process is not complicated. In addition, in the light absorbing portion 40, stray light generated by the light incident on the lens unit 30 being reflected by the inner peripheral surface 20a of the lens barrel 20 can be suppressed from becoming harmful light for the image formed by the lens unit.

[0050] Example 1 As configurations corresponding to the lens with a lens barrel 10 according to the above embodiment, configurations E1, R1, R2, and R3 shown in Figures 5(a), 5(b), and 5(c) were provided, and measurements were made to see how much light incident on this configuration was reflected by each layer.

[0051] In the first reference configuration R1 for comparison shown on the left side of FIG. 5(a), a glass material layer 62 corresponding to the lens portion 30, made of Sumita Optical Glass Co., Ltd., K-PBK40 (model number) (glass transition point: 501°C, yield point: 549°C, softening point: 626°C) with a diameter of 6 mm and a thickness of 2.1 mm, was placed on an aluminum metal mirror 61.

[0052] In the configuration E1 shown on the right side of FIG. 5(a) as Example 1 of the above embodiment, a filter layer 63 corresponding to the light absorbing section 40 is placed on a metal mirror 61 corresponding to the lens barrel 20, and a glass material layer 62 corresponding to the lens section 30 is placed on the filter layer 63. In this configuration E1, the metal mirror 61 is common to the first reference configuration R1. The filter layer 63 is a near-infrared absorption filter SCM504 (model number) (glass transition point: 508°C, yield point: 556°C, softening point: 620°C (expected value)) manufactured by Sumita Optical Glass Co., Ltd., which is a square of 5 mm×5 mm in plan view and has a thickness of 1 mm. The glass material layer 62 has the same configuration as the glass material layer 62 of the first reference configuration R1, and uses K-PBK40 manufactured by Sumita Optical Glass Co., Ltd.

[0053] Here, the temperature ranges from the yield point to the softening point of the K-PBK40 (glass material layer 62) and the near-infrared absorption filter SCM504 (filter layer 63) overlap. Specifically, the temperature range of 64°C from the yield point of 556°C to the softening point of 620°C of the near-infrared absorption filter SCM504 is included in the temperature range of K-PBK40 from the yield point of 549°C to the softening point of 626°C.

[0054] A second reference configuration R2 for comparison shown in FIG. 5(b) has a glass material layer 62 having the same configuration as the glass material layer 62 of the first reference configuration R1.

[0055] The third reference configuration R3 for comparison shown in Figure 5 (c) is a configuration in which the metal mirror 61 is not provided in the configuration E1 of Example 1, and more specifically, a glass material layer 62 is placed on the filter layer 63.

[0056] For the above configurations E1 and R1 to R3, the reflectance was measured under the following conditions. Measurement equipment: Reflectance measurement function of industrial microscope USPM-RU (Olympus Corporation) was used. The reflectance was measured by focusing on the surface to be measured. Measurement light: Incident angle 45 degrees, spot diameter 0.1 mm Measurement light wavelength range: 380nm~800nm

[0057] In each of the above configurations E1 and R1 to R3, the glass material layer 62 was disposed at the top, and the measurement light was incident on the upper surface of the glass material layer 62 as indicated by the dashed arrow.

[0058] The surfaces to be measured are as follows: S1: Upper surface of metal mirror 61 (FIG. 5(a)) S2: The top or bottom surface of the glass material layer 62 (FIG. 5(a), FIG. 5(b), FIG. 5(c)) S3: Interface between metal mirror 61 and glass layer 62 (FIG. 5(a)) S4: The bottom surface of the filter layer 63 of the third reference configuration R3 (FIG. 5(c)) S5: Interface between metal mirror 61 and filter layer 63 (FIG. 5(a))

[0059] For the measurement surfaces S3 and S5, a simulation was performed under the following conditions, and the simulated values ​​of the reflectance for light in the wavelength range of 380 nm to 800 nm were calculated. (1) Simulation value SS3 for measurement target surface S3: “Reflectance between glass material layer 62 and metal mirror 61”דDouble-sided transmittance of glass material layer 62”דAbsorption coefficient of glass material layer 62” (2) Simulation value SS5 for measurement target surface S5: "Reflectance between the glass layer 62, the filter layer 63, and the metal mirror 61" x "double-sided transmittance of the glass layer 62" x "absorption coefficient of the glass layer 62"

[0060] FIG. 6 is a graph showing the change in reflectance versus wavelength of measurement light for each of the measurement target surfaces S1 to S5 in the configurations shown in FIGS. 5(a), 5(b), and 5(c), and the change in reflectance for simulation values ​​SS3 and SS5.

[0061] As shown in Figure 6, the reflectance of the measurement target surface S3 in the first reference configuration R1 and the corresponding simulation value SS3, i.e., the reflectance at the interface between the metal mirror 61 and the glass layer 62, was a high value of 70% or more, close to the reflectance at the measurement target surface S1, which is the upper surface of the metal mirror 61, over the entire wavelength range.

[0062] The measurement surfaces S2 and S4 had a low reflectance of about 5% over the entire wavelength range.

[0063] On the other hand, the reflectance of the measurement target surface S5 in the configuration E1 as Example 1 and the corresponding simulation value SS5, i.e., the reflectance at the interface between the metal mirror 61 and the filter layer 63, decreased sharply in the wavelength range longer than 550 nm and became almost zero in the red and near-infrared ranges longer than 650 nm. Therefore, it was found that when the glass material layer 62 is disposed on the metal mirror 61 exhibiting high reflectance via the filter layer 63, the light incident from the glass material layer 62 to the filter layer 63 is absorbed in the near-infrared range by the light absorption function of the filter layer 63, and almost no light returns to the glass material layer 62.

[0064] Example 2 Next, the influence of the difference in refractive index between two adjacent materials on the reflectance will be described with reference to Figures 7 to 9. Figures 7 to 9 are graphs showing the results of simulation calculations of the change in reflectance (vertical axis, unit: %) of reflected light from the bonded surface relative to the change in incident angle (horizontal axis, unit: degrees) on the surface of a sample (Example 2) in which two glass plates with different refractive indexes are bonded together, when measurement light is incident on the surface of the sample.

[0065] The refractive indices of the samples in Figures 7, 8, and 9 are as shown in Tables 1, 2, and 3, respectively. Samples B11 to B17 shown in Figure 7 and samples B31 to B34 shown in Figure 9 are configured so that the refractive index n1 of the glass plate on the incident side, i.e., the first glass plate, is higher than the refractive index n2 of the second glass plate, and samples B21 to B26 shown in Figure 8 are configured so that the refractive index n2 of the second glass plate is higher than the refractive index n1 of the glass plate on the incident side.

[0066] In the samples shown in FIG. 7 and Table 1, the ratio (unit: %) of |n1-n2| (the absolute value of the difference between n1 and n2) to n1 as the difference in refractive index increases in the order of B11, B12, B13, B14, B15, B16, and B17, and |n1-n2| is the same for B16 and B17.

[0067] As shown in Fig. 7, for all samples, the reflectance is zero when the incident angle is in the range of 0 to 60 degrees. Sample B17, which has the largest ratio of |n1-n2| to n1, begins to increase in reflectance from an incident angle of approximately 70 degrees, and reaches a total reflection state with a reflectance of 100% at approximately 76 degrees. The incident angle at which the reflectance starts to increase increases as the ratio of |n1-n2| to n1 decreases, and the same is true for the incident angle at which the reflectance reaches a total reflection state with a reflectance of 100%.

[0068] According to this result, for samples B11 to B16 in which the ratio of |n1-n2| to n1 is 2.5% or less, the reflectance becomes 100% at an incident angle of approximately 80 degrees or more. Therefore, in a configuration in which the light absorbing section 40 is disposed on the radial outside of the lens section 30, like the barrel-equipped lens 10 of the above embodiment, it is considered that most of the incident light from the lens section 30 to the light absorbing section 40 is incident at an incident angle sufficiently smaller than 80 degrees, and therefore an effect of suppressing strong reflection or total reflection at the interface between the lens section 30 and the light absorbing section 40 can be expected.

[0069] [Table 1]

[0070] In the samples shown in FIG. 8 and Table 2, the ratio (unit: %) of |n1-n2| to n1, as the difference in refractive index, increases in the order of B21, B22, B23, B24, B25, and B26.

[0071] As shown in FIG. 8, in all samples, the reflectance is zero when the angle of incidence is in the range of 0 to 70 degrees. Sample B26, which has the largest ratio of |n1-n2| to n1, begins to increase in reflectance from an angle of incidence of approximately 75 degrees, and reaches a state of total reflection with a reflectance of 100% at 90 degrees. The angle of incidence at which the reflectance starts to increase increases as the ratio of |n1-n2| to n1 decreases. Furthermore, the angle of incidence at which the reflectance reaches a state of total reflection with a reflectance of 100% is 90 degrees in all samples, and does not reach a state of total reflection below 90 degrees.

[0072] According to this result, for samples B21 to B25 in which the ratio of |n1-n2| to n1 is 2.5% or less, the reflectance starts to increase at an incident angle of approximately 80 degrees or more. Therefore, in a configuration in which the light absorbing section 40 is disposed on the radial outside of the lens section 30, like the lens with a lens barrel 10 of the above embodiment, most of the incident light from the lens section 30 to the light absorbing section 40 is considered to be incident at an incident angle sufficiently smaller than 80 degrees, and therefore an effect of suppressing strong reflection at the interface between the lens section 30 and the light absorbing section 40 can be expected.

[0073] [Table 2]

[0074] 9 and Table 3, the ratio (unit: %) of |n1-n2| to n1 as the difference in refractive index is 2.5 for B31 and B34, larger than 2.5 for B32, and smaller than 2.5 for B33. |n1-n2| is the same for B31, B32, and B33.

[0075] 9, sample B32, which has the largest ratio of |n1-n2| to n1, begins to show an increase in reflectance from an incident angle of approximately 70 degrees, and reaches a state of total reflection with a reflectance of 100% at approximately 77 degrees. The incident angle at which the reflectance starts to increase increases as the ratio of |n1-n2| to n1 decreases, and the same is true for the incident angle at which the reflectance reaches a state of total reflection with a reflectance of 100%.

[0076] According to this result, in the case of samples B31, B33, and B34 in which the ratio of |n1-n2| to n1 is 2.5% or less, the reflectance becomes 100% at an incident angle of 78 degrees or more, and therefore, in a configuration in which the light absorbing portion 40 is disposed on the radial outside of the lens portion 30 like the lens with lens barrel 10 of the above embodiment, most of the incident light from the lens portion 30 to the light absorbing portion 40 is considered to be incident at an incident angle sufficiently smaller than 78 degrees, and therefore an effect of suppressing strong reflection or total reflection at the interface between the lens portion 30 and the light absorbing portion 40 can be expected. Moreover, while samples B31 and B34 have the same ratio of |n1-n2| to n1 at 2.5, |n1-n2| is different numerical values, but show almost the same change in FIG. 9.

[0077] [Table 3] [Explanation of symbols]

[0078] 10, 110 Lens with lens barrel 20, 120 telescope 20a, 120a Inner surface 20b Outer surface 21 Bottom 30, 130 Lens section 30a, 130a Outer edge 30m Lens material 31 First lens surface 31m Bottom center of raw material 32 Second lens surface 33 End face 40, 140 Light absorbing part 40m Light absorbing part raw material 41 End face 42 Inner surface 50 mold 51 Upper mold 51a Profile material 51b Bottom side 51c First Optical Surface 52 Lower mold 52a Bottom wall 52b Top surface 52c Second Optical Surface 52d Circular recess 52e Side wall part 52f Inner surface 61 Metal mirror 62 Glass layer 63 Filter Layer 131 Lens surface 132 plane 133 End face 141 End face A1, A11 central part A2, A12 periphery AX optical axis B11, B12, B13, B14, B15, B16, B17 Samples of Example 2 B21, B22, B23, B24, B25, B26 Samples of Example 2 B31, B32, B33, B34 Samples of Example 2 D3, D4 thickness D13, D14 maximum thickness E1 Configuration as Example 1 R1, R2, R3 Reference Configuration S1, S2, S3, S4, S5 Measurement surface SS3, SS5 simulation values

Claims

1. A metal lens barrel and a glass lens portion provided in the lens barrel; a light absorbing portion made of glass provided between an inner peripheral surface of the lens barrel and an outer edge portion of the lens portion in a radial direction of the lens barrel, a first temperature range from a deformation point to a softening point of a first glass material constituting the lens portion and a second temperature range from a deformation point to a softening point of a second glass material constituting the light absorbing portion have overlapping temperature ranges, A lens with a lens barrel, wherein a first glass transition point which is a glass transition point of the first glass material is higher than a second glass transition point which is a glass transition point of the second glass material.

2. 2. The lens with a lens barrel according to claim 1, wherein the overlapping temperature range is 10[deg.] C. or higher.

3. 3. The lens with a lens barrel according to claim 1, wherein a difference in refractive index between the first glass material and the second glass material is within ±2.5%.

4. 4. The lens with a lens barrel according to claim 1, wherein the lens portion has a lens surface that exerts a predetermined refractive effect on at least one of end faces of the lens portion in the optical axis direction.

5. 5. The lens with a lens barrel according to claim 4, wherein a surface made of the second glass material is located between the lens surface and the lens barrel so as to be continuous with the lens surface.

6. the lens portion includes a central portion having the lens surface, and a peripheral portion provided on an outer edge of the central portion in a radial direction of the lens portion, 6. The lens with a lens barrel according to claim 4, wherein a ratio of a thickness of the light absorbing portion in the direction of the optical axis to a thickness of the peripheral portion is 0.8 or more.

7. 7. The lens with a lens barrel according to claim 1, wherein the second glass material has a light absorption band that is not present in the first glass material.

8. A lens with a lens barrel as described in claim 7, wherein the second glass material is a near-infrared absorbing glass that can absorb more light in the near-infrared region than the first glass material.

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