JP2012031020A - Glass lens, and molding die for glass lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass lens capable of preventing its flange part from being reduced in strength and preventing generation of stray light due to incidence of unnecessary light onto the boundary between a lens part and the flange part.SOLUTION: An odd-shaped stray-light suppression part 104 located at the boundary between the central main part 100a and the peripheral flange part 100b in the glass lens 100 blocks the unnecessary incident light into the boundary or turns the light away from the optical path. The unnecessary incident light into the boundary is thus prevented, and generation of the stray light that causes noise is prevented, while reduction in the strength of the flange part 100b is prevented.

Description

  The present invention relates to a glass lens obtained by pressing a molten glass material obtained from droplets between a pair of upper and lower molds and a molding die thereof, and more particularly to a small glass lens incorporated in an optical pickup device.

  As a glass lens, it is a glass lens obtained by pressing a glass drop with an upper and lower mold, and in order to prevent the occurrence of cracks and cracks at the boundary part between the lens part and the flange part, the boundary part is more than the flange surface. One that forms a depressed recess is known (see Patent Document 1).

JP 2005-320199 A

  However, in the glass lens of the above-mentioned patent document 1, since the concave portion of the boundary portion is deep and local, stress tends to concentrate, and the strength of the flange portion after molding tends to decrease. In particular, small glass lenses used in recent optical pickup devices and other applications tend to be lighter and thinner, and the thickness of the flange portion tends to be thin. When a deep recess is locally provided, the strength of the flange portion Will fall.

  As a modified version of the press method for manufacturing the glass lens described in Patent Document 1, the side surface of the flange portion is obtained by pressing the molten glass material obtained from the droplets with the upper and lower molds and the outer periphery regulating mold. There are also those that obtain the final form without centering.

  In the glass lens obtained by pressing the glass droplet as described above, the flange portion can be made to have a uniform thickness without forming a recess at the boundary portion between the lens portion and the flange portion. In this case, it is possible to avoid a reduction in the strength of the glass lens, but unnecessary light is incident on the flat, mirror-like boundary portion, causing stray light, that is, noise. Although it is conceivable that the boundary portion is painted, etc., the operation is not easy with a small glass lens.

  Therefore, an object of the present invention is to provide a glass lens that can prevent a decrease in strength of the flange portion and prevent stray light from being generated due to unnecessary light entering a boundary portion between the lens portion and the flange portion.

  Another object of the present invention is to provide a glass lens molding die for molding the above glass lens.

  In order to solve the above problems, a glass lens according to the present invention includes a main body portion disposed in the center and an annular flange portion disposed around the main body portion, and at the boundary between the main body portion and the flange portion, A stray light suppressing portion having an uneven shape is provided. Note that the uneven shape of the stray light suppressing portion deviates from the shape in which the outer edge of the main body portion or the inner edge of the flange portion is extended.

  In the glass lens, since the stray light suppressing portion having the uneven shape is provided at the boundary between the main body portion and the flange portion, unnecessary light incident on the boundary can be shielded by the stray light suppressing portion or escaped from the optical path. . Here, the stray light suppression unit can be shallow and wide. Thereby, it is possible to suppress generation of stray light due to unnecessary light entering the boundary while preventing a decrease in strength of the flange portion.

  In a specific aspect or aspect of the present invention, in the glass lens, the upper and lower surfaces of the main body portion and the upper and lower surfaces of the flange portion press the molten glass formed from droplets between the lower die and the upper die. The outer peripheral side surface of the flange portion is formed by an outer peripheral regulating member that restricts expansion of the molten glass. In this case, the final form of the glass lens having the main body portion and the flange portion can be obtained by a single press by the droplet forming method.

  In another aspect of the present invention, the stray light suppressing portion is formed by transferring the mold surface. In this case, the shape of the stray light suppression unit can be in a desired state, and the function of eliminating unnecessary light by the stray light suppression unit can be made more reliable.

  In still another aspect of the present invention, the surface of the stray light suppressing unit is a non-optical surface. In this case, the image-like action can be suppressed in the stray light suppressing unit, and the generation of stray light can be reliably suppressed. The non-optical surface means a surface that does not have an optical function such as a main body with respect to the macroscopic or microscopic shape accuracy of the surface.

  In still another aspect of the present invention, the stray light suppressing portion is formed in a non-contact state with respect to the mold surface. In this case, the transfer surface of the lower mold or the upper mold can be made relatively simple. The stray light suppression portion thus formed is generally recessed from the flat surface of the flange portion, and is preferably formed on both the first optical surface side and the second optical surface side. That is, the stray light suppressing portion formed in a non-contact state, that is, the non-transfer area tends to be unclear, so from the viewpoint of securing a sufficient stray light preventing function, the first optical surface side and the second optical surface It is desirable to be formed on both sides. In the case where the stray light suppressing portion, that is, the non-transfer area is formed on either the first optical surface side or the second optical surface side, it is desirable to form it on the recording medium side.

  In still another aspect of the present invention, the stray light suppressing portion is formed on each of the outer peripheral side of the first optical surface of the main body portion and the outer peripheral side of the second optical surface of the main body portion. In this case, it becomes possible to suppress stray light for both unnecessary light incident from the first optical surface side and unnecessary light incident from the second optical surface side.

  In still another aspect of the present invention, the stray light suppressing portion is formed in a concentric groove shape with a pitch in the range of 20 μm to 500 μm.

  In still another aspect of the present invention, the stray light suppressing portion is roughened in a surface roughness range of 0.1 nm to 100 nm.

  In still another aspect of the present invention, the glass lens is an objective lens for an optical pickup. In this case, noise light generated at the boundary between the main body portion and the flange portion can be suppressed, and the accuracy of reading and writing by the objective lens can be increased.

  A molding die for a glass lens according to the present invention includes a lower mold, an upper mold, and an outer periphery regulating member, and a main body disposed at the center by pressurizing molten glass formed from droplets, and a main body A molding die for molding a glass lens having an annular flange portion arranged around a portion, wherein at least one of a lower die and an upper die has a transfer surface for a main body portion and a flange portion A stray light suppressing transfer portion having an uneven shape deviating from a shape obtained by extending the outer edge of the main body portion and the inner edge of the flange portion is provided at the boundary with the transfer surface.

  In the molding die for glass lens, since the stray light suppression transfer portion having an uneven shape is provided at the boundary between the transfer surface for the main body portion and the transfer surface for the flange portion, the main body is formed by a droplet forming method. A stray light suppressing portion having an uneven shape corresponding to the stray light suppressing transfer portion can be formed at the boundary between the portion and the flange portion. In the glass lens thus obtained, unnecessary light incident on the boundary can be shielded by the stray light suppressing portion or escaped to the outside of the optical path, and the stray light suppressing portion provided thereon can be shallow and broad. Thereby, it is possible to suppress generation of stray light due to unnecessary light entering the boundary while preventing a decrease in strength of the flange portion. In addition, since the outer peripheral side surface of the glass lens can be directly formed by providing the outer periphery regulating member, and post-processing such as centering of the glass lens is not required, cracks are hardly formed at the time of production or assembly, and the glass The strength and yield of the lens can be increased.

(A), (B) is sectional drawing and the top view of the glass lens which concerns on 1st Embodiment of this invention. It is a figure which illustrates notionally the shaping | molding apparatus for manufacturing the glass lens of FIG. FIG. 3 is a side sectional view for explaining a molding die and the like in the molding apparatus of FIG. 2. It is a partial expanded sectional view for demonstrating the shaping | molding process of the glass lens using the shaping die of FIG. (A) is sectional drawing of the glass lens which concerns on 2nd Embodiment, (B) is a partial expanded sectional view explaining the shaping die for shape | molding a glass lens. (A) is sectional drawing of the glass lens which concerns on 3rd Embodiment, (B) is a partial expanded sectional view explaining the shaping die for shape | molding a glass lens. (A) is sectional drawing of the glass lens which concerns on 4th Embodiment, (B) is a partial expanded sectional view explaining the shaping die for shape | molding a glass lens. (A) is sectional drawing of the glass lens which concerns on 5th Embodiment, (B) is a partial expanded sectional view explaining the shaping die for shape | molding a glass lens. (A) is sectional drawing of the glass lens which concerns on 6th Embodiment, (B) is a partial expanded sectional view explaining the shaping die for shape | molding a glass lens.

[First Embodiment]
The glass lens 100 of the first embodiment shown in FIG. 1 can be used as an objective lens incorporated in a pickup device, for example. The glass lens 100 includes a central portion 100a as a main body having an optical function, and an annular flange portion 100b extending radially outward from the central portion 100a. The glass lens 100 is, for example, a BD (Blu-ray Disc) having a wavelength of 405 nm and a NA of 0.85, a DVD (Digital Versatile Disc) having a wavelength of 655 nm and a NA of 0.65, and other information recording media corresponding to a specific standard. Enable reading or writing.

  In the illustrated glass lens 100, a first lens surface 101a having a relatively large curvature is formed on one side (lower side of the drawing, light source side) of the thick central portion 100a, and the other side of the central portion 100a (drawing). A first lens surface 102a having a relatively small curvature is formed on the upper side (information recording medium side). Also, a ring-shaped first flange surface 101b perpendicular to the optical axis OA is formed on one side (lower side of the drawing, light source side) of the flange portion 100b, and the other side (upper side of the drawing, information recording medium) of the flange portion 100b. The second flange surface 102b having an annular shape perpendicular to the optical axis OA is formed on the side. Further, a cylindrical outer peripheral side surface 103c extending in parallel with the optical axis OA is formed around the flange portion 100b.

Here, a stray light suppressing portion 104 extending in a ring shape is formed at the boundary between one first lens surface 101a of the central portion 100a and one first flange surface 101b of the flange portion 100b. The stray light suppressing portion 104 is a non-optical surface having a concavo-convex shape deviating from a flat shape obtained by extending the outer edge of the center portion 100a or the inner edge of the flange portion 100b, and specifically, around the optical axis OA. It is a forming surface of a corrugated section type formed in a periodic concentric groove shape. However, the stray light suppressing unit 104 as a whole extends substantially along a ring-shaped plane extending perpendicular to the optical axis OA. The pitch of the stray light suppressing unit 104, that is, the groove width gw ₁ (see FIG. 4) is in the range of 20 μm to 500 μm in the present embodiment. Further, the groove depth gd ₁ of the stray light suppressing unit 104 is about ₁ to 0.1 with respect to the groove width gw ₁ . The stray light suppressing portion 104 is formed at the time of molding the glass lens 100 and has a microscopically smooth surface. In addition, by setting the pitch of the stray light suppressing unit 104 to 20 μm or more and 500 μm or less, it is possible to suppress the tendency of incident light to go straight and enhance the stray light suppressing effect. Further, by setting the groove depth gd ₁ of the stray light suppressing unit 104 to about ₁ to 0.1 with respect to the groove width gw ₁ , the unevenness of the stray light suppressing unit 104 is moderate enough to deflect the optical path of unnecessary light. Can be. Further, the groove depth gd _{1 in} the optical axis OA direction of the stray light suppressing unit 104 is about 0.0016 to 0.69 on the basis of the flange thickness t ₁ that is the thickness of the flange portion 100 b in the optical axis OA direction. . Thereby, the stray light suppression effect can be enhanced while ensuring the strength of the flange portion 100b.

The radial width perpendicular to the optical axis OA of the stray light suppression unit 104, that is, the suppression region width W ₁ (see FIGS. 1 and 4) is 0.0028 to about the lens outer diameter d ₀ that is the outer diameter of the glass lens 100. It is 0.17. Further, suppression region width _{W 1} has a 0.0045 to 0.25 approximately, based on the first Men径_{d 1} is the outer diameter of the first lens surface 101a. Suppression region width W ₁ of the stray light suppression unit 104, within the above range, the diameter of the light beam incident on the first lens surface 101a, is appropriately set in consideration of the fluctuation range or the like.

  The glass lens 100 may be provided with a diffraction or other fine structure on the first lens surface 101a disposed on the light source side, for example. When the fine structure is provided in this way, the glass lens 100 becomes an objective lens that can easily realize reading or writing of optical information corresponding to, for example, any of two or more standards.

  Hereinafter, with reference to FIG. 2, 3 etc., the shaping | molding apparatus for manufacturing the glass lens 100 of FIG. 1 is demonstrated.

  A molding apparatus 200 shown in FIG. 2 is a so-called direct press apparatus, and includes a raw material supply unit 50 and a control drive device 60 in addition to a molding die 10 for shape transfer. Although omitted in FIG. 2, the molding die 10 has an upper die 2 that can be disposed facing the lower die 1 as shown in FIG. 3.

  The raw material supply unit 50 includes a melting crucible 51 for melting glass and a molten glass supply nozzle 52 for dropping glass. The raw material supply unit 50 is heated by the heaters 50a and 50b, and the glass in the melting crucible 51 and the molten glass supply nozzle 52 is brought into a molten state with an appropriate viscosity by the heaters 50a and 50b.

  The molten crucible 51 stores molten glass G obtained by heating and stirring the raw materials, and continuously supplies the molten glass G to the molten glass supply nozzle 52 connected to the bottom of the molten crucible 51. The molten glass supply nozzle 52 causes the molten glass G in the melting crucible 51 to be discharged from the discharge portion 52a at the lower end, and drops the discharged molten glass G as a glass droplet GD at a desired periodic timing. The discharge part 52a has an inner diameter that matches the target flow rate of the molten glass G, and has a tapered inner surface shape that moderately expands downward in order to adjust the size and dropping period of the glass droplet GD. Thereby, when the molten glass G collected in the discharge part 52a reaches an appropriate amount, the molten glass supply nozzle 52 drops the molten glass G as a glass droplet GD by its own weight. At this time, the glass droplet GD is dropped from the raw material supply unit 50 in a relatively low viscosity (high temperature) state, falls toward the lower mold 1, and has a relatively low viscosity when landing on the lower mold 1. It sticks in the state deform | transformed according to the surface shape of the lower mold | type 1 by colliding with.

  Hereinafter, the details of the molding die 10 will be described with reference to FIG. The molding die 10 includes a lower die 1, an upper die 2, and an outer periphery regulation frame 3.

  As shown in FIG. 3, the lower mold 1 of the molding die 10 includes a mold body 1a for transfer. The mold body 1a forms an optical surface transfer surface 11a for forming the first lens surface 101a of the glass lens 100 shown in FIG. 1 and a first flange surface 101b as the lower mold transfer surface 11 at the time of molding. The flange surface transfer surface 11b. Further, as shown in FIG. 4, a boundary transfer surface 14 d is provided at the boundary between the optical surface transfer surface 11 a and the flange surface transfer surface 11 b as a stray light suppression transfer portion for forming the stray light suppression portion 104 of the glass lens 100. Is provided. The optical surface transfer surface 11a, the flange surface transfer surface 11b, and the boundary transfer surface 14d are defined by the lower end surface of the mold body 1a. These transfer surfaces 11a, 11b, and 14d are formed by machining such as grinding or coating with a metal thin film or the like. The mold body 1a can be a single member, but can also be composed of a plurality of members such as a mold and a nested mold. The lower mold 1 has a heater 20a for heating the mold main body 1a appropriately.

  Of the lower mold transfer surface 11, the boundary transfer surface 14d in particular has a periodic protrusion formed concentrically, and the surface shape obtained by inverting this periodic protrusion is transferred to the glass droplet GD or the glass lump GG. Is done. When a large number of rectangular grooves are formed on the boundary transfer surface 14d, the stray light suppression unit 104 has a pattern in which a large number of protrusions extending in a bowl shape are formed at the bottom of the recess. As shown in the enlarged view, the hook-shaped protrusions constituting the stray light suppressing unit 104 of the specific example are not exactly transferred from the rectangular groove of the boundary transfer surface 14d, but have an effect of deflecting the optical path of unnecessary light. .

  The upper mold 2 includes a mold body 2a for transfer. The mold main body 2a forms an optical surface transfer surface 12a for forming the second lens surface 102a of the glass lens 100 shown in FIG. 1 and a second flange surface 102b as the upper mold transfer surface 12 at the time of molding. Flange surface transfer surface 12b. The optical surface transfer surface 12a and the flange surface transfer surface 12b are defined by the upper end surface of the mold body 2a. These transfer surfaces 12a and 12b are formed by machining such as grinding or coating with a metal thin film or the like. The mold body 2a can be a single member, but can also be composed of a plurality of members such as a mold and a nested mold. The lower mold 1 has a heater 20b for heating the mold main body 2a appropriately.

  The outer periphery regulation frame 3 is fixed in an aligned state with respect to the mold body 2a of the upper mold 2. The outer periphery restriction frame 3 has an outer periphery transfer surface 13c as an outer periphery restriction surface for forming the outer periphery side surface 103c of the glass lens 100. The outer periphery regulating frame 3 has a function of directly forming the outer peripheral side surface 103c of the glass lens 100 as a final product by transfer. The outer peripheral transfer surface 13c is a tapered surface that slightly expands downward in consideration of mold release of the glass lens 100.

  The operation of the molding die 10 is controlled by the control drive device 60 together with the raw material supply unit 50. For example, the control drive device 60 can drive the upper mold 2 and move it in the horizontal AB direction, and can move it in the vertical CD direction. When the molds 1 and 2 are closed together, first, the upper mold 2 is moved to the upper position of the lower mold 1 so that the center axes CX1 and CX2 of the both molds 1 and 2 coincide with each other. Lower and press against the lower mold 1 side with a predetermined force.

  As shown in the partially enlarged cross-sectional view of FIG. 4, there is a slight gap between the lower end of the mold body 2 a of the upper mold 2 and the upper end of the outer periphery regulating frame 3 so that the molten glass lump GG cannot sufficiently enter. GP1 is provided. Further, when the lower mold 1 and the upper mold 2 are combined, the lower end of the outer periphery regulating frame 3 and the upper end of the mold main body 1a of the lower mold 1 are close to each other, and the glass lump GG is melted between them. As a result, a small gap GP2 is formed so that the obtained glass cannot sufficiently enter. At the time of pressure molding, the air accumulated in the mold space sandwiched between the mold bodies 1a and 2a is discharged to the outside through the upper and lower gaps GP1 and GP2.

  As described above, in the glass lens 100 according to the present embodiment, the stray light suppressing portion 104 having the concavo-convex shape is provided at the boundary between the central portion 100a that is the main body portion and the surrounding flange portion 100b. Unnecessary light incident on the boundary between the surface 101a and the first flange surface 101b can be shielded by the stray light suppressing unit 104 or escaped from the optical path. Thereby, it is possible to prevent stray light that causes noise due to incidence of unwanted light on the boundary while preventing a decrease in strength of the flange portion 100b.

  In the case of the present embodiment, a convex part ip for forming a concave part of the stray light suppressing part 104 (a part recessed from the first flange face 101b) is formed on the innermost circumference of the boundary transfer surface 14d. For this reason, since the sharp projection is not formed at the boundary from the optical surface transfer surface 11a of the lower mold 1 to the boundary transfer surface 14d, the transfer surface becomes relatively continuous, so that a V groove is formed in the glass lens 100. Therefore, it is possible to prevent the occurrence of chipping and the like.

  Furthermore, in the case of this embodiment, since the outer peripheral side surface 103c is directly formed by the outer peripheral restriction frame 3, post-processing such as centering of the glass lens 100 becomes unnecessary, and the flange portion 100b and stray light suppression are suppressed at the time of manufacture and assembly. Cracks are less likely to be formed in the portion 104. Thereby, the intensity | strength and yield of the glass lens 100 can be raised.

以上の実施例Ａ〜Ｊにおいて、迷光抑制部１０４を構成する各溝の溝幅ｇｗ_１は、０．００３ｍｍ〜０．１ｍｍ（３μｍ〜１００μｍ）程度の範囲とし、各溝の溝深さｇｄ_１は、０．００３ｍｍ〜０．０７ｍｍ（３μｍ〜７０μｍ）程度の範囲とした。結果的に、溝深さｇｄ_１に対するフランジ厚ｔ_１の比は、以下の表２のような範囲となった。つまり、この比ｔ_１／ｇｄ_１は、最小で４．３５となり、最大で１９１となった。

以上の実施例Ａ〜Ｊにおいて、溝深さｇｄ_１が最大溝時である０．０７ｍｍ又は最小溝時の０．００３ｍｍである場合、すなわち抑制領域幅Ｗ_１が最大時の０．２ｍｍ又は最小時の０．０１ｍｍである場合、抑制領域幅Ｗ_１に対するガラスレンズ１００の半径ｄ_０／２の比（〔ｄ₀／２〕／Ｗ_１）、及び第１レンズ面１０１ａの半径ｄ_１／２の比（〔ｄ_１／２〕／W_１）、は、以下の表３のような値となった。なお、抑制領域幅Ｗ_１は、光抑制部１０４の光軸ＯＡに垂直な半径方向の幅を意味する。

表３からも明らかなように、抑制領域幅Ｗ_１に対するガラスレンズ１００の半径ｄ_０／２の比（〔ｄ₀／２〕／W_１）は、６〜３５０程度の範囲にあり、抑制領域幅Ｗ_１に対する第１レンズ面１０１ａの半径ｄ_１／２の比（〔ｄ_１／２〕／W_１）は、４〜２２０程度の範囲にある。 [Example 1]
Table 1 below summarizes the appearance dimensions ratio of specific embodiments A~J (ratio of each unit to the lens outer diameter d _0). In Table 1, first Men径_{d 1} denotes the outer diameter of the first lens surface 101a, a second Men径_{d 2} denotes the outer diameter of the second lens surface 102a, a flange inner diameter _{d 3} is means a diameter of the inner edge of the flange portion 100b, the lens on-axis thickness t ₂ is meant an optical axis OA of the thickness of the central portion 100a (see FIG. 1).

In the above Examples A to J, the groove width gw ₁ of each groove constituting the stray light suppressing unit 104 is in the range of about 0.003 mm to 0.1 mm (3 μm to 100 μm), and the groove depth gd _{1 of} each groove. Was in the range of about 0.003 mm to 0.07 mm (3 μm to 70 μm). As a result, the ratio of the flange thickness t ₁ to the groove depth gd ₁ was in the range shown in Table 2 below. That is, the ratio t ₁ / gd ₁ was 4.35 at the minimum and 191 at the maximum.

In Examples A to J above, when the groove depth gd ₁ is 0.07 mm at the time of the maximum groove or 0.003 mm at the time of the minimum groove, that is, the suppression region width W ₁ is 0.2 mm at the maximum or the maximum. If it is 0.01mm small time, the ratio of the radius _d 0/2 of the glass lens 100 for suppressing region width _{W 1} ([d _{0/2] / W} 1), and the radius _d 1/2 of the first lens surface 101a the ratio of _([d 1/2] / W _1), has a value shown in Table 3 below. Note that the suppression region width W ₁ means a width in the radial direction perpendicular to the optical axis OA of the light suppression unit 104.

Table 3 As is apparent from the ratio of the radius _d 0/2 of the glass lens 100 for suppressing region width _{W 1} ([d _0/2] / W ₁₎ is in the range of about 6-350, suppression area the width _{W 1} ratio of radius _d 1/2 of the first lens surface 101a _([d 1/2] / W ₁₎ is in the range of about 4-220.

[Second Embodiment]
Hereinafter, the glass lens of 2nd Embodiment which concerns on this invention is demonstrated. The glass lens of 2nd Embodiment deform | transforms the glass lens of 1st Embodiment, and the part which is not demonstrated especially is the same as that of 1st Embodiment.

  As shown in FIG. 5A, in the case of the glass lens 100 of the second embodiment, not only the stray light suppressing portion 104 is formed at the boundary between the first lens surface 101a and the first flange surface 101b, The stray light suppression unit 204 is also formed at the boundary between the two lens surfaces 102a and the second flange surface 102b.

  As shown in FIG. 5B, in the upper mold 2, as a stray light suppression transfer portion for forming the stray light suppression portion 204 of the glass lens 100 at the boundary between the optical surface transfer surface 12a and the flange surface transfer surface 12b. A ring-shaped boundary transfer surface 214d extending substantially along a plane perpendicular to the optical axis OA is provided.

[Example 2]
Since the external dimensions of specific examples are the same as those of Examples A to J shown in Table 1, description thereof will be omitted. Further, the stray light suppressing unit 104 provided on the first lens surface 101a side is also the same as in Examples A to J, and thus description thereof is omitted. The groove width gw ₂ of each groove constituting the stray light suppressing unit 204 provided on the second lens surface 102a side is set to a range of about 0.003 mm to 0.1 mm (3 μm to 100 μm), and the groove depth gd _{2 of} each groove. Was in the range of about 0.0003 mm to 0.016 mm (0.3 μm to 16 μm). Note that the groove width gw ₁ and groove depth gd ₁ of each groove constituting the stray light suppressing unit 104 are the same as those in Example 1 (specifically, in the case of Examples A to J shown in Table 1). Description is omitted. In this embodiment, the ratio of the flange thickness t ₁ with respect to the groove depth gd ₂ is a range shown in Table 2, supra (Table 2 has a common table the first and second embodiments) It was. That is, the ratio t ₁ / gd ₂ was 17.4 at the minimum and 1910 at the maximum. The ratio t ₁ / gd ₁ for the stray light suppression unit 104 is 4.35 to 191 as in the first embodiment.
In the second embodiment, when the groove depths gd ₁ and gd ₂ are 0.07 mm and 0.016 mm at the time of the maximum groove or the minimum 0.003 mm and 0.0003 mm, the suppression region widths W ₁ and W Regarding ₂ (= W ₁ ), the results shown in Table 3 above (Table 3 is a table common to the first and second embodiments) were obtained.
Table 3 As is apparent from the ratio of the radius _d 0/2 inhibition region width _{W 1, W 2 (= W} 1) glass lens 100 for ([d _0/2] / W ₁₎ is 6-350 in the range of degree, the radius _d 1/2 ratio of the first lens surface 101a for suppressing region width _{W 1} of the stray light suppression unit 104 _([d 1/2] / _{W 1)} is in the range of about 4-220 There, the radius _d 2/2 ratio of the second lens surface 102a for suppressing region width _{W 2} of the stray light suppression unit 204 _([d 2/2] / _{W 2)} is in the range of about 2-180.

[Third Embodiment]
Hereinafter, the glass lens of 3rd Embodiment which concerns on this invention is demonstrated. The glass lens of 3rd Embodiment deform | transforms the glass lens of 1st Embodiment, and the part which is not demonstrated especially is the same as that of 1st Embodiment.

  As shown in FIG. 6A, in the glass lens 100 of the third embodiment, the boundary between the first lens surface 101a of the central portion 100a and the first flange surface 101b of the flange portion 100b extends in a ring shape. A stray light suppression unit 304 is formed. The stray light suppression unit 304 is a non-optical surface having a concavo-convex shape, and more specifically, a minute concavo-convex type formed surface that is uniformly roughened. The stray light suppression unit 304 as a whole extends substantially along a ring-shaped plane extending perpendicular to the optical axis OA. The surface roughness of the stray light suppressing unit 304 is in the range of 0.1 nm to 100 nm in the present embodiment. The stray light suppressing portion 304 is formed at the same time when the glass lens 100 is molded, and has a microscopically smooth surface in that it does not have cracks like polished glass. In addition, by setting the surface roughness of the stray light suppressing unit 304 to 0.1 nm or more, it is possible to suppress the tendency of the incident light to go straight and enhance the stray light suppressing effect. Moreover, it can prevent that the unevenness | corrugation of the stray light suppression part 304 becomes deep by making the surface roughness of the stray light suppression part 304 into 100 nm or less. Note that the thickness of the stray light suppressing unit 304 in the optical axis OA direction is extremely small compared to the thickness of the flange 100b, and the strength of the flange 100b is kept sufficiently strong.

  As shown in FIG. 6B, in the lower mold 1 of the molding die 10 (see FIG. 3), the stray light suppressing portion of the glass lens 100 is located at the boundary between the optical surface transfer surface 11a and the flange surface transfer surface 11b. A boundary transfer surface 314 d is provided as a stray light suppression transfer portion for forming 304. The boundary transfer surface 314d is roughened, and this rough surface state is transferred to the glass droplet GD or the glass lump GG.

  A stray light suppression unit similar to the stray light suppression unit 304 can be provided at the boundary between the second lens surface 102a and the second flange surface 102b.

[Fourth Embodiment]
Hereinafter, the glass lens of 4th Embodiment which concerns on this invention is demonstrated. The glass lens of 4th Embodiment deform | transforms the glass lens of 1st Embodiment, and the part which is not demonstrated especially is the same as that of 1st Embodiment.

  As shown in FIG. 7A, in the case of the glass lens 100 according to the fourth embodiment, the stray light suppression unit 404 formed at the boundary between the first lens surface 101a and the first flange surface 101b has an optical axis OA. Although it is an annular unevenness formed concentrically around it, the size of the unevenness is large, and it has a relatively simple structure including a pair of concave portions sandwiching a relatively large convex portion having a bowl shape. Furthermore, the most projecting portion (the apex of the convex portion) of the stray light suppressing portion 404 is arranged on the extended plane of the first flange surface 101b or behind it, and the glass lens 100 is attached to the first flange surface 101b. It is possible to prevent the stray light suppressing unit 404 from interfering when installed and fixed using it.

  As shown in FIG. 7B, in the lower mold 1, as a stray light suppression transfer portion for forming a stray light suppression portion 404 of the glass lens 100 at the boundary between the optical surface transfer surface 11a and the flange surface transfer surface 11b. A boundary transfer surface 414d is provided. In this case, since the pattern of the boundary transfer surface 414d is large, the stray light suppressing portion 404 is formed in close contact with the boundary transfer surface 414d and according to the mold surface. Further, a convex portion for forming a concave portion of the stray light suppressing portion 404 is formed on the innermost circumference of the boundary transfer surface 414d, and the transfer is performed from the optical surface transfer surface 11a of the lower mold 1 to the boundary transfer surface 414d. The continuity of the surface is maintained, the lower mold 1 can be easily manufactured, and breakage of the glass lens 100 such as chipping can be prevented.

  In the stray light suppressing portion 404, if the number of annular irregularities constituting the stray light suppressing portion 404 is increased, the relative thickness of the stray light suppressing portion 404 with respect to the flange portion 100b can be reduced, and the stress concentration can be suppressed. Can reliably increase the strength of the glass lens 100.

  Further, the stray light suppressing unit 404 can be provided not only on the outer peripheral side of the first lens surface 101a but also on the outer peripheral side of the second lens surface 102a.

[Fifth Embodiment]
The glass lens according to the fifth embodiment of the present invention will be described below. The glass lens of 5th Embodiment deform | transforms the glass lens of 1st Embodiment, and the part which is not demonstrated especially is the same as that of 1st Embodiment.

  As shown in FIG. 8A, in the case of the glass lens 100 of the fifth embodiment, the stray light suppressing portion 504 formed at the boundary between the first lens surface 101a and the first flange surface 101b is a single annular shape. It has a relatively simple structure with a shallow recess. Similarly, the stray light suppressing portion 604 formed at the boundary between the second lens surface 102a and the second flange surface 102b has a relatively simple structure including a single annular shallow concave portion.

  As shown in FIG. 8B, as the stray light suppression transfer portion for forming the stray light suppression portion 504 of the glass lens 100 at the boundary between the optical surface transfer surface 11a and the flange surface transfer surface 11b in the lower mold 1. A boundary transfer surface 514d is provided. Similarly, in the upper mold 2, a boundary transfer surface 614 d is provided at the boundary between the optical surface transfer surface 12 a and the flange surface transfer surface 12 b as a stray light suppression transfer portion for forming the stray light suppression portion 604 of the glass lens 100. It has been. In this case, the stray light suppressing portions 504 and 604 are formed in close contact with the boundary transfer surfaces 514d and 614d according to the mold surface. Since the boundary transfer surfaces 514d and 614d have smooth convex portions for forming the concave portions of the stray light suppressing portions 504 and 604, the optical transfer surfaces 11a and 12a of the molds 1 and 2 are used. The continuity of the transfer surface to the boundary transfer surfaces 514d and 614d is maintained, making the molds 1 and 2 easy, and preventing breakage of the glass lens 100 and the like.

Example 3
The external dimensions of specific examples are the same as those of Examples A to J shown in Table 1. The definition of the dimension of each part is the same as that shown in FIG. The groove width gw ₁ of the stray light suppressing portion 504 provided on the first lens surface 101a side is in the range of about 0.01 mm to 0.3 mm, and the groove depth gd ₁ is in the range of about 0.01 mm to 0.2 mm. It was. Groove width gw ₂ of the stray light suppression unit 604 which is provided on the second lens surface 102a side, a range of about 0.01Mm～0.3Mm, the groove depth gd ₂ is in the range of about 0.001mm~0.05mm It was. As shown in Table 4 below, the ratio _t 1 / gd ₁ of the flange thickness _{t 1} with respect to the groove depth gd ₁ is 1.45 to 63.8, and the ratio of the flange thickness _{t 1} with respect to the groove depth gd ₂ t _{The 1} / gd ₂ ratio is 5.8 to 638.

[Sixth Embodiment]
The glass lens according to the sixth embodiment of the present invention will be described below. The glass lens of 6th Embodiment deform | transforms the glass lens of 1st Embodiment, and the part which is not demonstrated especially is the same as that of 1st Embodiment.

  As shown in FIG. 9A, in the case of the glass lens 100 of the sixth embodiment, the stray light suppressing portion 704 formed at the boundary between the first lens surface 101a and the first flange surface 101b is a single annular shape. It has a relatively simple structure with a shallow recess. Similarly, the stray light suppressing portion 804 formed at the boundary between the second lens surface 102a and the second flange surface 102b has a relatively simple structure including a single annular shallow concave portion.

  As shown in FIG. 9B, in the lower mold 1, the boundary between the optical surface transfer surface 11 a and the flange surface transfer surface 11 b is a flat surface with the flange surface transfer surface 11 b extended, and the stray light suppressing unit 704. It is not a stray light suppression transfer portion for transferring the shape in contact with the surface. Similarly, in the upper mold 2, the boundary between the optical surface transfer surface 12 a and the flange surface transfer surface 12 b is a flat surface with the flange surface transfer surface 12 b extended, and the shape is transferred in contact with the stray light suppressing unit 804. This is not a stray light suppression transfer portion.

  In the case of the present embodiment, the stray light suppressing portions 704 and 804 are not forcibly formed by the transfer surfaces of the lower mold 1 and the upper mold 2, but the size and temperature of the glass droplet GD or the glass lump GG are adjusted, the lower mold 1 In addition, the shallow concave surfaces of the stray light suppressing portions 704 and 804 are formed in a non-contact manner by adjusting the tightening force of the upper die 2, the size and temperature of the outer peripheral restriction frame 3, and the like. The stray light suppressing portions 704 and 804 formed in a non-contact state, that is, the non-transfer area, are provided on both the first lens surface 101a side and the second lens surface 102a side from the viewpoint of ensuring a sufficient stray light prevention function. However, for example, only the stray light suppression unit 804 on the second lens surface 102a side facing the optical recording medium may be omitted, and the stray light suppression unit 704 on the first lens surface 101a side may be omitted.

The shape of a specific example was substantially the same as that of the fifth embodiment. That is, the groove width gw ₁ of the stray light suppressing unit 704 is set to a range of about 0.01 mm to 0.3 mm, and the groove depth gd ₁ is set to a range of about 0.01 mm to 0.2 mm. Further, the groove width gw ₂ of the stray light suppressing unit 804 is set to a range of about 0.01 mm to 0.3 mm, and the groove depth gd ₂ is set to a range of about 0.001 mm to 0.05 mm.

  Also in the glass lens 100 of the sixth embodiment, unnecessary light incident on the boundary between the lens surfaces 101a and 102a can be shielded or escaped to the outside of the optical path by the stray light suppressing portions 704 and 804, and the strength of the flange portion 100b is reduced. The generation of stray light can be suppressed while preventing the above. In addition, when forming the glass lens 100 of 6th Embodiment, the shape freedom degree of the lower mold | type 1 and the upper mold | type 2 can be raised.

  Although the mold apparatus and the like according to the embodiment have been described above, the mold apparatus and the like according to the present invention are not limited to the above.

  That is, in the first, third, and fourth embodiments, the stray light suppression units 104, 304, and 404 are formed on the outer peripheral side of the first lens surface 101a. It can also be provided only on the outer peripheral side of the two lens surfaces 102a.

  For example, in the second embodiment, the cross-section wave type stray light suppressing portions 104 and 204 are formed on both sides of the flange portion 100b. However, either one of the stray light suppressing portions 104 and 204 is replaced with a micro uneven type stray light suppressing portion. It can also be replaced with 304 or the like.

  In the first and second embodiments, the stray light suppressing portions 104 and 204 are periodic protrusions formed in a concentric groove shape. However, it is not necessary to set the intervals between the concentric grooves at equal pitches, and the same stray light is used. The pitch may change regularly or irregularly in the suppression units 104 and 204.

  In the first to sixth embodiments, the stray light suppressing portions 104, 204, 304, 404 and the like are formed in an annular shape around the central portion 100a, but stray light is suppressed in a part of the angular region of the outer edge of the central portion 100a. The portions 104, 204, 304, 404, and the like can be provided. In this case, the generation of stray light can be suppressed at least in the region where the stray light suppressing portions 104, 204, 304, 404, and the like are provided.

  In the second, fifth, and sixth embodiments, the width of one stray light suppressing unit 104, 504, 704 and the width of the other stray light suppressing unit 204, 604, 804 can be substantially equal. It can be different.

  In the above embodiment, a small depression that does not affect the lens strength and optical characteristics may be formed at the boundary between the first lens surface 101a of the glass lens 100 and the stray light suppressing unit 104 and the like.

DESCRIPTION OF SYMBOLS 1 ... Lower mold | type, 1a, 2a ... Mold main body, 2 ... Upper mold | type, 3 ... Outer periphery control frame, 10 ... Molding die, 11 ... Lower mold transfer surface, 11a ... Optical surface transfer surface, 11b ... Flange surface transfer surface, DESCRIPTION OF SYMBOLS 12 ... Upper die transfer surface, 12a ... Optical surface transfer surface, 12b ... Flange surface transfer surface, 13c ... Outer periphery transfer surface, 14d, 214d, 314d, 414d ... Boundary transfer surface, 20a, 20b ... Heater, 50 ... Raw material supply part 60 ... Control drive device 100 ... Glass lens 100a ... Center part 100b ... Flange part 101a, 102a ... Lens surface 101b, 102b ... Flange surface 103c ... Outer peripheral side 104, 204, 304, 404, 504 , 604, 704, 804 ... stray light suppression unit, 200 ... molding device, CX1, CX2 ... central axis, G ... molten glass, GD ... glass droplet GG ... glass mass, OA ... optical axis

Claims (10)

A main body disposed in the center;
An annular flange portion disposed around the body portion;
A glass lens, wherein a stray light suppressing portion having an uneven shape is provided at a boundary between the main body portion and the flange portion. The upper and lower surfaces of the main body portion and the upper and lower surfaces of the flange portion are formed by pressing molten glass formed from droplets between a lower mold and an upper mold,
The glass lens according to claim 1, wherein an outer peripheral side surface of the flange portion is formed by an outer peripheral regulating member that restricts expansion of the molten glass.   The glass lens according to claim 2, wherein the stray light suppressing portion is formed by transferring a mold surface.   The glass lens according to claim 3, wherein the surface of the stray light suppressing portion is a non-optical surface.   The glass lens according to claim 2, wherein the stray light suppressing portion is formed in a non-contact state with respect to the mold surface.   The said stray light suppression part is each formed in the outer peripheral side of the 1st optical surface of the said main-body part, and the outer peripheral side of the 2nd optical surface of the said main-body part, respectively. The glass lens as described in any one.   The glass lens according to any one of claims 1 to 6, wherein the stray light suppressing portion is formed in a concentric groove shape with a pitch in a range of 20 µm to 500 µm.   The glass lens according to any one of claims 1 to 6, wherein the stray light suppressing portion is roughened in a surface roughness range of 0.1 nm to 100 nm.   The glass lens according to any one of claims 1 to 8, wherein the glass lens is an objective lens for an optical pickup. A lower die, an upper die, and an outer periphery regulating member, and by pressurizing molten glass formed from droplets, a main body portion arranged in the center, and an annular flange portion arranged around the main body portion, A molding die for molding a glass lens having
In at least one of the lower mold and the upper mold, the outer edge of the main body and the inner edge of the flange are extended from the boundary between the transfer surface for the main body and the transfer surface for the flange. A molding die for a glass lens, characterized in that a stray light suppressing transfer portion having an uneven shape is provided.

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