JP2011204335A - Method for manufacturing optical element, optical element, and objective lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing an optical element preventing generation of a burr on a ridge line of remains formed by cutting a gate part in an outer peripheral part of the optical element after the gate part is cut off.SOLUTION: Burr generation in a lens 100 can be prevented by cutting ridge line part 103d along the ridge line of remains formed by cutting the gate part GP after cutting the gate part GP remaining in a flange part 102 of the lens 100. The lens 100 is accurately provided when the lens 100 is attached to a device and a tool. Since a boundary 103b between a bottom surface 102d and a cutting surface 103a is not made sharp by forming a ridge line working part 103c in a corner chamfered shape, the ridge line working part 103c is hardly damaged during conveyance, assembling and the like.

Description

  The present invention relates to a method for manufacturing an optical element such as a plastic lens, an optical element manufactured using the method, and an objective lens.

  Among optical element manufacturing methods, there is an optical element finishing method in which an unnecessary gate portion formed at the time of molding an optical element is cut off (see Patent Document 1, etc.). This prevents the gate portion from remaining on the outer peripheral portion of the optical element and enables the optical element to be mounted on a device, a jig, or the like.

JP 2001-272501 A

  However, the method of manufacturing an optical element as disclosed in Patent Document 1 has a problem in that the outer peripheral portion of the optical element from which the gate portion has been removed is left uncut, that is, burrs, on the upper and lower ridge lines of the removal trace of the gate portion. In this case, it is difficult to accurately install the optical element when the optical element is mounted on a device, a jig, or the like.

  Therefore, the present invention provides an optical element manufacturing method for preventing burrs from occurring on the ridgeline of the gate part excision trace in the outer peripheral part of the optical element from which the gate part has been cut, an optical element manufactured using the optical element, and an objective. The object is to provide a lens.

  In order to solve the above problems, a method of manufacturing an optical element according to the present invention includes a target part cutting step of cutting a gate portion continuously formed on the outer peripheral portion of the optical element, and a target part cutting step after the target part cutting step. And a ridge line processing step of cutting the ridge line portion along the ridge line of the cut trace of the gate portion.

  In the manufacturing method of the optical element, after the gate portion remaining in the optical element is excised, the ridge line portion is cut along the ridge line of the cut trace of the gate portion, thereby preventing the optical element from being burred. Can do. Thereby, when mounting an optical element on an apparatus or a jig | tool, it can install correctly.

  In a specific aspect of the present invention, the target portion cutting step includes a first cutting step of cutting off and separating the boundary between the optical element and the gate portion, and the gate portion remaining on the outer peripheral portion after the first cutting step. And a second cutting step for excising the material. In this case, the gate portion can be easily and precisely cut out by dividing the gate portion into two stages.

  In another aspect of the present invention, the second cutting step and the ridge line processing step are performed simultaneously. In this case, the ridge line processing step can be performed efficiently and quickly.

  In still another aspect of the present invention, the ridge line portion of the optical element is cut into a chamfered shape in the ridge line processing step. In this case, the ridgeline of the excision trace of the gate portion is not sharp, so that the ridgeline processing portion of the outer peripheral portion after cutting the ridgeline portion is less likely to be damaged during transportation or assembly.

  In still another aspect of the present invention, the chamfered shape is any one of a square chamfered shape and an R chamfered shape. Here, the square chamfered shape is a chamfered shape in which intersecting surface portions are cut at a predetermined inclination angle, and the R chamfered shape is a chamfered shape in which intersecting surface portions are cut into round shapes. In this case, by setting the chamfered shape to one of the square chamfered shape and the R chamfered shape, the optical element can be easily attached to the assembly portion or the positioning portion of the apparatus or the jig.

  In still another aspect of the present invention, the angle of chamfering is 30 degrees or more and 60 degrees or less. In this case, by setting the angle of the chamfered shape to 30 degrees or more and 60 degrees or less, the ridgeline of the cut trace of the gate portion can be made into a substantially chamfered shape that is not sharp.

  In still another aspect of the present invention, the optical element is a multi-wavelength compatible lens having an optical path difference providing structure including a plurality of steps on at least a part of an optical function surface provided in the optical unit. In this case, a high-precision multi-wavelength compatible lens can be assembled with high accuracy by preventing burrs from occurring in the optical element. The optical path difference providing structure referred to in this specification is a general term for structures that provide an optical path difference with respect to an incident light beam. The optical path difference providing structure also includes a phase difference providing structure for providing a phase difference. The phase difference providing structure includes a diffractive structure. The optical path difference providing structure of the present invention is preferably a diffractive structure. The optical path difference providing structure has a step, preferably a plurality of steps. This step gives an optical path difference and / or a phase difference to the incident light flux.

  In still another aspect of the present invention, at least one of excision and cutting is performed using an end mill in the target part cutting step and the ridge line processing step. In this case, by using an end mill, the optical element can be precisely finished by mechanical cutting.

  In order to solve the above-described problems, an optical element according to the present invention includes an optical unit having an optical function surface and an outer peripheral part provided around the optical part, and a cut mark of a gate part formed in the outer peripheral part. The ridge line processing portion has a chamfered shape. In this case, an optical element with reduced generation of burrs can be obtained. Thereby, when mounting an optical element on an apparatus or a jig | tool, it can install correctly. In addition, since the ridge line processing portion of the excision trace of the gate portion has a chamfered shape, the ridge line is not sharp, and the ridge line processing portion is less likely to be damaged during transportation or assembly.

  In another aspect of the present invention, it has a ridge line processing part provided in the excision trace of the gate part in the outer peripheral part, and a molding chamfered part provided in an area excluding the excision trace of the gate part in the outer peripheral part, The ridge line processed portion is smaller than the formed chamfered portion. In this case, since the ridge line processed portion is smaller than the molded chamfered portion, the ridge line portion of the cut trace of the gate portion can be cut without substantially affecting the shape of the optical element that is the molded product.

In the objective lens of the present invention, the optical element is an objective lens for an optical pickup, and the following formula 0.9 ≦ d / f ≦ 1.8 (1)
It is characterized by satisfying. Here, it is assumed that the thickness of the objective lens on the optical axis is d (mm), and the focal length of the objective lens in the light beam having the wavelength λ1 is f (mm). In this case, even when the optical element is an objective lens compatible with, for example, a short wavelength, high NA optical disk (for example, BD), astigmatism and surface shift sensitivity are suppressed by satisfying the above formula (1). It becomes possible. Further, since dust adherence to the optical functional surface is reduced, even an objective lens compatible with an optical disk with a short wavelength and a high NA can be easily manufactured and handled.

(A) is a front view of the lens according to the first embodiment, (B) is a side view of the lens shown in (A), and (C) is a lens shown in (A). It is a B arrow side view. It is a block diagram explaining a processing apparatus. (A), (B) is the top view and side view of a chuck apparatus etc. which were integrated in the processing apparatus of FIG. 2 for processing the lens of FIG. It is a side view explaining the lens which concerns on 2nd Embodiment. FIG. 5 is a side view of a chuck device and the like incorporated in a processing apparatus for processing the lens of FIG. 4. It is a side view explaining the lens which concerns on 3rd Embodiment. FIG. 7 is a side view of a chuck device and the like incorporated in a processing apparatus for processing the lens of FIG. 6. It is a side view explaining the lens which concerns on 4th Embodiment.

[First Embodiment]
Hereinafter, an optical element and a method for manufacturing the optical element according to the first embodiment of the present invention will be described with reference to the drawings.

  A lens 100 shown in FIGS. 1A, 1B, and 1C is a small resin-made diffractive refractive compound lens. For example, a pickup such as a collimator lens or an objective lens used in an optical pickup device or the like. It is a lens. The lens 100 includes a main body portion 101 corresponding to an optical portion as an optical function portion having an optical function, and a flange portion 102 corresponding to an annular outer peripheral portion that extends to the outer periphery of the main body portion 101. In FIG. 1B and the like, the main body 101 includes a first optical surface OS1 having a large curvature on the upper side (laser light source side) and a second optical surface OS2 having a small curvature on the lower side (information recording medium side). Have In the main body 101, the first optical surface OS1 has a fine structure having a step of a diffractive structure (an optical path difference providing structure including a plurality of steps) in order to be compatible with multiple wavelengths. That is, the lens 100 is a three-wavelength compatible optical element corresponding to a short wavelength, high numerical aperture standard, a medium wavelength, medium numerical aperture standard, and a long wavelength, low numerical aperture standard. The fine structure provided on the optical surface OS1 has a shape that enables light collection in conformity with each wavelength. In the example shown in the figure, the first optical surface OS1 is divided into three concentric regions to correspond to three-wavelength light beams having different numerical apertures, and the three-wavelength compatible region AR1 and two wavelengths from the inside toward the outside. The compatible area AR2 and the one-wavelength dedicated area AR3 are included. By all these areas AR1, AR2, AR3, for example, the light is condensed by selectively diffracting the wavelength (405 nm) of a BD (Blu-ray Disc) with a numerical aperture (NA) of 0.85, and on the BD optical disk. To form the optimal spot. Further, by selectively diffracting the wavelength (650 nm) of a DVD (Digital Versatile Disc) with a numerical aperture (NA) of 0.6, for example, by the areas AR1 and AR2 excluding the most peripheral side away from the optical axis OA. The light is condensed to form an optimum spot on the DVD optical disk. In addition, the area AR1 on the optical axis OA side, for example, condenses light by selectively diffracting the wavelength (780 nm) of a CD (Compact Disc) with a numerical aperture (NA) of 0.45, and is optimal on a CD optical disc. A perfect spot.

  The flange portion 102 has an annular portion 102b having an annular surface 102a that serves as a reference surface when the lens 100 is assembled and measured, and a cylindrical support that extends from the annular portion 102b to the second optical surface OS2 side of the main body 101. Part 102c. The annular surface 102a of the annular portion 102b extends perpendicular to the optical axis OA, and the support portion 102c extends parallel to the optical axis OA. The support portion 102c is provided to support the lens 100, and has an annular bottom surface 102d on the lower side. The support portion 102c has a role of protecting the second optical surface OS2 when the lens 100 is stored or transported. The support portion 102c has a shallow notch-shaped cut portion 103 formed by finishing after molding on a part of the outside thereof.

  The cutting portion 103 is obtained by removing a specific region of the side surface SS of the support portion 102c at once in the thickness direction, that is, the optical axis OA direction. The cutting part 103 is located on the side surface SS side of the support part 102c and is separated from the main body part 101 by a substantially constant distance. The cutting portion 103 is a concave portion that is slightly depressed in the radial direction along the flange portion 102 in plan view, and has a convex cylindrical surface 103a as a whole. As shown in FIG. 1B, the chamfering process (for example, C chamfering process) is performed on the boundary 103b between the bottom surface 102d and the cut surface 103a, which is the lower surface of the flange part 102, and the ridgeline part 103d is removed. The remaining ridgeline processing portion 103c has a sloped chamfered shape. Specifically, the inclination angle θ1 of the ridge line processing portion 103c is, for example, 30 degrees or more and 60 degrees or less, and in the case of a C chamfered shape, θ1 = 45 degrees. Moreover, the height H of the ridgeline processing part 103c is, for example, not less than 1/100 mm and not more than 1/10 mm.

  Before the lens 100 is processed, the gate portion GP is formed on the side surface SS of the flange portion 102, that is, a part of the support portion 102c. In the processed lens 100, the gate portion is formed along with the formation of the cutting portion 103. GP has been removed. On the lower side of the cut trace of the gate portion GP, the ridgeline portion 103d is cut at the boundary 103b between the bottom surface 102d and the cut surface 103a for the purpose of removing burrs and the like, and the ridgeline having the above-described shape characteristics A processed portion 103c is formed. That is, in the present embodiment, the gate portion GP and a part of the support portion 102c (processing region A0) for forming the cutting portion 103 in the lens 100 before processing are removed by cutting or cutting. It is a processing target part.

Hereinafter, with reference to FIG. 2 etc., the processing apparatus and processing method of the lens 100 shown to FIG. 1 (A) etc. are demonstrated.
FIG. 2 is a diagram illustrating a processing apparatus used for processing the lens 100. The processing apparatus 10 is an apparatus for removing the gate portion GP and the like from the lens 100 to be processed. The processing apparatus 10 includes a holder device 20, a cutting unit 30, an NC device 40, a dust collecting device 60, and a control device 70.

  First, the holder device 20 includes a support stage 21 and a chuck device 22 as lens holders. The chuck device 22 detachably fixes the lens 100 as a lens support portion. At this time, the chuck device 22 supports the lens 100 from one lower surface side to hold the lens 100 horizontally, and the gate portion GP formed on a part of the outer periphery of the lens 100 faces the cutting unit 30 side. Hold on.

  As shown in FIGS. 3A and 3B, the chuck device 22 includes a support base 81, movement limiting members 82 a and 82 b, a rear chuck portion 83, and an upper surface chuck portion 84. The support base 81 has a support surface 81a and a recess 81b. The support surface 81a is a flat surface that supports the bottom surface 102d of the flange portion 102 of the lens 100 and keeps the lens 100 horizontal. The concave portion 81 b is for housing a protrusion when the projection is formed on the lower side of the main body portion 101 of the lens 100, and is provided on the distal end side of the support base 81. Here, the lens 100 is placed so that the lower side of the main body 101, that is, the second optical surface OS2 is on the support base 81 side. Thus, the support surface 81a or the recess 81b protects the second optical surface OS2 on the lower side of the main body 101 of the lens 100 during processing. Of the lens 100 fixed to the holder device 20, the gate portion GP and other processing target portions are disposed so as to protrude from the front side of the support base 81, so that the processing by the cutting unit 30 is not hindered. Yes.

  The pair of movement restricting members 82a and 82b are formed on the distal end side of the support base 81, that is, on the −X side. Both the movement limiting members 82a and 82b are triangular prism-shaped members, for example, and their side surfaces 82c and 82c extend perpendicularly to the support surface 81a. When the side surfaces 82c and 82c of the movement limiting members 82a and 82b are in contact with the side surface SS of the support portion 102c of the lens 100, the movement of the lens 100 to the −X side is limited. The rear chuck portion 83 is disposed behind the pair of movement restriction members 82 a and 82 b and behind the support base 81. The rear chuck portion 83 includes a push rod 83a that can move forward and backward toward the side surface SS of the lens 100, and a rod drive portion 83b that moves the push rod 83a forward and backward. The end surface 83c of the push rod 83a abuts on the side surface SS of the lens 100 in the advanced operation state, and urges the side surface SS with an appropriate pressure. Accordingly, the lens 100 can be fixed on the support base 81 in an aligned state so as to be sandwiched between the pair of movement limiting members 82a and 82b and the push rod 83a. Note that by slightly rotating the lens 100 on the support base 81 immediately before fixing the lens 100, the gate portion GP can be adjusted so as to be accurately directed to the front, that is, in the −X direction with respect to the optical axis OA. .

  The upper surface chuck portion 84 is disposed above the support base 81 and the like. The upper surface chuck portion 84 includes a cylindrical member 84a that can move forward and backward toward the annular surface 102a of the flange portion 102 of the lens 100, and a cylindrical member drive portion 84b that moves the cylindrical member 84a forward and backward. The end surface 84c of the cylindrical member 84a lightly contacts the annular surface 102a of the flange portion 102 of the lens 100 in the advanced operation state, and urges the annular surface 102a of the flange portion 102 downward with an appropriate pressure. Accordingly, the lens 100 is sandwiched between the support base 81 and the cylindrical member 84a, and the fixing of the lens 100 can be stabilized. Thus, fixing the lens 100 can reliably prevent the lens 100 from rotating during processing by the end mill 31. The cylindrical member 84a also has a function of protecting the first optical surface OS1 on the upper side of the main body 101 of the lens 100 during processing.

  Returning to FIG. 2, the cutting unit 30 includes an end mill 31, a rotation driving unit 33, and a dust collecting cover 34 as processing units. The end mill 31 of the cutting unit 30 is a cutting tool that removes the gate portion GP and the like incidentally formed on the lens 100 by mechanical cutting by rotating around an axis AX parallel to the Z axis. At this time, as shown in FIGS. 3 (A), 3 (B), etc., not only the gate part GP but also a part of the support part 102c of the flange part 102 as a part to be processed, The processing area A0 including the portion corresponding to the inverted shape 103 is removed. The end mill 31 forms a cutting surface S1 corresponding to the cutting surface 103a by cutting a side surface of the gate portion GP or the like with the tip portion 31a. Simultaneously with the formation of the cutting surface S1, the ridge line portion 103d is cut from the boundary 103b between the bottom surface 102d of the flange portion 102 and the cut surface 103a to form the ridge line processing portion 103c (see FIG. 1). Here, as illustrated in FIG. 3B, the end mill 31 has a root portion R1 of the tip 31a having a predetermined inclination angle θ2 with respect to the axis AX. For example, in the case of C chamfering, the inclination angle θ2 is 45 degrees. As a result, the gate portion GP remaining on the flange portion 102 is removed, and a ridge line processing portion 103c having a chamfered shape with a desired inclination angle θ1 (= θ2) is added to the ridge line processing portion 103c shown in FIG. Can be provided. The rotation drive unit 33 shown in FIG. 2 rotates the end mill 31 at a high speed around an axis AX parallel to the optical axis OA of the lens 100. The dust collection cover 34 is fixed to a frame member (not shown) that supports the rotation drive unit 33. The dust collection cover 34 covers the end mill 31 as a whole, prevents the cutting powder from scattering from the portion processed by the end mill 31, and partially exposes the processing blade portion of the end mill 31.

  The NC device 40 is a position driving device that can support the cutting unit 30 and shift it two-dimensionally. In this case, the cutting unit 30 is moved linearly or curvedly in a direction perpendicular to the optical axis OA with respect to the holder device 20, so that the gate of the lens 100 corresponds to the rotation locus and the movement locus of the end mill 31. Part GP and other parts to be processed can be excised. The NC device 40 has a structure capable of adjusting the position of the cutting unit 30 in the optical axis OA direction.

  The dust collector 60 includes an intake device 61 and a suction duct 62. The intake device 61 has an exhaust fan and a filter. The suction duct 62 extends from the intake device 61 and is connected to the rear portion of the dust collection cover 34 provided in the cutting unit 30. The suction duct 62 sucks excised powder generated in the dust collection cover 34, that is, around the end mill 31, and sends it to the intake device 61.

  The control device 70 comprehensively controls the operation of the processing device 10 as a whole, controls the holding operation of the lens 100 by the holder device 20, and controls the cutting operation of the lens 100 by the cutting unit 30 and the NC device 40. The operation of the dust collector 60 is controlled.

  Hereinafter, the processing steps of the lens 100 will be described. In the present embodiment, the processing step includes cutting a target portion cutting step for cutting the gate portion GP, and cutting a boundary 103b between the bottom surface 102d and the cut surface 103a in the cut portion of the gate portion GP in the lens 100 after the target portion cutting step. And a ridge line processing step.

  Using the processing apparatus 10 of FIG. 2, as a target part cutting process, first, a first cutting process for cutting and separating the boundary between the flange part 102 and the gate part GP of the lens 100, and a flange part after the first cutting process. A second cutting step is performed in which the gate portion GP remaining on the flange portion 102 is removed from the 102. In the first cutting step, the lens 100 and the gate portion GP are separated by cutting near the base of the gate portion GP extending to the flange portion 102 of the lens 100 that is a molded product using a nipper, a cutter, or the like. At this time, the gate portion GP is slightly left in the flange portion 102.

  Next, in the second cutting step, the gate portion GP remaining on the flange portion 102 is cut using the end mill 31 of FIG. A ridge line processing step is also performed in parallel with the second cutting step, and the ridge line portion 103d is cut along the ridge line of the excision trace of the gate portion GP of the lens 100. Specifically, the end mill 31 moves at a constant speed in the −Y direction along the outer periphery of the flange portion 102 while rotating around the axis AX at a high speed. At this time, the ridgeline portion 103 d is removed together with the gate portion GP outside the side surface SS of the flange portion 102. As a result, the cut surface S1, that is, the cut surface 103a and the ridge line processed portion 103c are formed as the cut trace or the cut surface.

  In the optical element manufacturing method, after the gate portion GP remaining on the flange portion 102 of the lens 100 is cut, the ridge line portion 103d is cut along the ridge line of the cut mark of the gate portion GP, whereby the lens 100 is variably formed. Can be prevented. Thereby, when mounting the lens 100 on an apparatus or a jig | tool, it can install correctly. In addition, by making the ridge line processing portion 103c into a square chamfered shape, the boundary 103b between the bottom surface 102d and the cut surface 103a is not sharp, so that the ridge line processing portion 103c is less likely to be damaged during transportation or assembly.

  Further, the optical element manufactured by the above manufacturing method has a fine structure such as a diffractive structure in particular because dust does not adhere to the optical surfaces OS1 and OS2 of the lens 100 by preventing the lens 100 from generating burrs. Since a small amount of dust enters between the fine structures, it is possible to easily manufacture and handle the highly accurate lens 100 such as a multi-wavelength compatible lens that greatly affects the optical performance.

The optical element manufactured by the above manufacturing method uses, for example, laser light having a wavelength λ1 of 390 nm or more and 420 nm or less, and the required numerical aperture (NA) is 0.9 or less and 0.75 or more, respectively. In the case of an objective lens used for an optical disk (for example, BD), the thickness d (mm) on the optical axis of the objective lens and the focal length f (mm) of the objective lens in the light flux with wavelength λ1 are expressed by the following equations. It is preferable to satisfy.
0.9 ≦ d / f ≦ 1.8 (1)
In the case of an objective lens corresponding to an optical disk with a short wavelength and a high NA, if the ratio of the thickness d on the optical axis to the focal length f of the objective lens becomes too large, an off-axis light beam is incident on the objective lens. There arises a problem that astigmatism is likely to occur or the working distance cannot be secured. On the other hand, if the ratio of the thickness d on the optical axis to the focal length f of the objective lens becomes too small, there arises a problem that the surface shift sensitivity increases. By satisfying the above formula (1), it is possible to suppress the generation of astigmatism and the surface shift sensitivity. In addition, the objective lens corresponding to such a short wavelength, high NA optical disc requires high-precision optical characteristics as compared with other objective lenses for DVD and CD, so that a slight amount of dust is attached. Is not allowed. That is, although the problem of dust adhesion becomes larger, the present invention can facilitate manufacture and handling even for an objective lens corresponding to a short wavelength, high NA optical disk having such a large problem. it can.

[Second Embodiment]
Hereinafter, the lens according to the second embodiment will be described. The lens according to the second embodiment is obtained by changing the lens 100 according to the first embodiment, and parts not specifically described are the same as those in the first embodiment.

  As shown in FIG. 4, the cut portion 203 formed in the lens 200 of the second embodiment matches the first embodiment in that it is a concave portion that is recessed in a direction perpendicular to the optical axis OA direction. The second embodiment is different from the first embodiment in that an R chamfering process is applied to a boundary 203b between a bottom surface 102d which is a lower surface of the flange portion 102 and a cut surface 203a. That is, the ridge line processing portion 203c of the lens 200 according to the second embodiment has an R chamfer shape. The height H of the ridge line processing portion 203c is, for example, 1/100 mm or more and 1/10 mm or less. The R-shaped dimension is preferably larger than the R-shape of the device for installing the lens 200, the assembly portion of the jig, and the positioning portion, although it depends on the method of attaching the lens 200.

  The lens 200 in FIG. 4 is processed using an end mill 231 as shown in FIG. As illustrated in FIG. 5, the end mill 231 has a base portion R <b> 1 of the tip portion 31 a rounded with respect to the axis AX. As a result, the gate portion GP remaining on the flange portion 102 is removed, and the ridge line portion 203d is cut from the ridge line of the cut portion of the gate portion GP of the flange portion 102 shown in FIG. 4, and a desired R chamfer is formed on the ridge line processing portion 203c. A shape can be provided.

[Third Embodiment]
Hereinafter, the lens according to the third embodiment will be described. The lens according to the third embodiment is obtained by changing the lens 100 according to the first embodiment, and parts not specifically described are the same as those in the first embodiment.

  As shown in FIG. 6, the cut portion 303 formed in the lens 300 of the third embodiment matches the first embodiment in that it is a concave portion that is recessed in a direction perpendicular to the optical axis OA direction. The second embodiment is different from the first embodiment in that the chamfering processing is also performed on the ridge line processing portion 303f of the boundary 303e between the annular surface 102a which is the upper surface of the flange portion 102 and the cut surface 303a. That is, the upper and lower ridgeline processing portions 303c and 303f of the lens 300 according to the third embodiment have a chamfered shape, for example, a C chamfered shape.

  The lens 300 in FIG. 6 is processed using an end mill 331 as shown in FIG. In the end mill 331, as illustrated in FIG. 7, the root portion R1 and the distal end portion R2 of the intermediate portion 331a in which only the diameter corresponding to the thickness of the flange portion is reduced have a predetermined inclination angle θ2 with respect to the axis AX. Have. Thereby, the gate portion GP remaining on the flange portion 102 is removed, and the ridgeline portions 303d and 303g are cut from the upper and lower ridgelines of the cut portion of the gate portion GP of the flange portion 102 shown in FIG. A corner chamfered shape having a desired inclination angle θ1 (= θ2), for example, a C chamfered shape can be provided at 303f.

  In the present embodiment, the end portion 331a of the end mill 331 having a base portion R1 and a tip portion R2 that are rounded with respect to the axis AX may be used. In this case, the ridge line processing portion of the upper and lower ridge lines has an R chamfer shape.

[Fourth Embodiment]
The lens according to the fourth embodiment will be described below. The lens according to the fourth embodiment is a modification of the lens 100 according to the first embodiment, and parts that are not particularly described are the same as those in the first embodiment.

  As shown in FIG. 8, the cut portion 403 formed in the lens 400 of the fourth embodiment is the same as that of the first embodiment in that it is a recess recessed in a direction perpendicular to the optical axis OA direction. The second embodiment is different from the first embodiment in that the upper and lower edges 402e of the flange portion 102 have relatively large molding chamfers 402f molded by a molding die. Here, although the normal molding chamfered part is also formed in the lens 100 according to the first embodiment, it is smaller than the relatively large chamfering as in the lens 400 according to the fourth embodiment.

  A ridge line processing portion 403c is formed on the ridge line below the cut portion of the gate portion GP in the lower edge portion 402e of the flange portion 102. That is, a molding chamfered portion 402f is formed in a region of the lower edge portion 402e on the lower side of the flange portion 102 excluding the cut mark. The height H1 of the ridge line processing portion 403c is smaller than the height H2 of the forming chamfered portion 402f. Specifically, the height H1 of the ridge line processing portion 403c is, for example, 1/100 mm or more and 1/10 mm or less, and the height H2 of the forming chamfered portion 402f is, for example, 5/100 mm or more. Thereby, the ridge line processing part 403c of the excision trace can be formed without substantially affecting the shape of the lens 400 that is a molded product.

  In the present embodiment, the ridge line processing portion 403c may have an R chamfer shape. Further, a corner chamfered shape or an R chamfered shape may be provided on the upper and lower ridge lines of the cut trace of the gate part GP.

  Although the present invention has been described based on the above embodiments, the present invention is not limited to the above embodiments, and various modifications are possible. For example, in the above-described embodiment, the first optical surface OS1 such as the lens 100 has a stepped microstructure, but a lens having no microstructure may be used.

  In the above embodiment, the cut portions 103, 203, 303, and 403 are recessed portions that are slightly recessed in the radial direction along the flange portion 102 in plan view, but the shapes of the cut portions 103, 203, 303, and 403 are changed as appropriate. can do. For example, the specific region of the side surface SS of the flange portion 102 may be linearly removed on a surface parallel to the optical axis OA direction.

  In the above embodiment, processing is performed by one end mill 31, 231, 331, but the gate portions GP of the lenses 100, 200, 300, 400 can also be removed by a plurality of end mills.

  In the above embodiment, the case where the end mills 31, 231, 331 are used as the cutting tools has been described. However, instead of the end mills 31, 231, 331, a gate unit using a grinding tool such as a grindstone or a file-like or blade-like processing tool. GP and the like can be removed.

  In the above embodiment, the gate portion GP and the like may be removed by cutting or the like with the end mill 31 or the like while rotating the lenses 100, 200, 300, and 400.

  In the said embodiment, although the 1st cutting process and the ridgeline process process were performed simultaneously, the end mills 31, 231, 331 may be driven appropriately, and each process may be performed separately.

  In the above embodiment, the height H of the ridge line processing portion of the ridge line is set to 1/100 mm or more and 1/10 mm or less, but may be appropriately changed depending on the shape and material of the lenses 100, 200, 300, and 400.

  In the fourth embodiment, the height H1 of the ridge line processing portion 403c is smaller than the height H2 of the molding chamfered portion 402f, but the height H1 of the ridge line processing portion 403c is smaller than the height H2 of the molding chamfered portion 402f. You may enlarge it.

  DESCRIPTION OF SYMBOLS 10 ... Processing apparatus, 20 ... Holder apparatus, 22 ... Chuck apparatus, 30 ... Cutting unit, 31,231,331 ... End mill, 33 ... Rotation drive part, 34 ... Dust collection cover, 40 ... NC apparatus, 60 ... Dust collector 61 ... Intake device, 62 ... Suction duct, 70 ... Control device, 81 ... Support base, 82a, 82b ... Movement limiting member, 84 ... Upper surface chuck part, A0 ... Processing region, AX ... Shaft, 100, 200, 300, 400 ... Lens, 101 ... Body part, 102 ... Flange part, 103,203,303,403 ... Cut part, 103a, 203a, 303a ... Cut surface, 103b, 203b, 303b, 303e ... Ridge line, 103c, 203c, 303c, 303f, 403c ... Ridge line processing part, 103d, 203d, 303d, 303g ... Ridge line part, GP Gate portion, OA ... optical axis, OS1, OS2 ... optical surfaces, S1 ... cutting plane, A0 ... processing region

Claims (14)

A target part cutting step of excising the gate part continuously formed on the outer peripheral part of the optical element;
After the target portion cutting step, a ridge line processing step of cutting the ridge line portion along the ridge line of the cut trace of the gate portion of the optical element,
An optical element manufacturing method comprising:   The target portion cutting step includes a first cutting step of cutting and separating a boundary between the optical element and the gate portion, and cutting the gate portion remaining on the outer peripheral portion from the outer peripheral portion after the first cutting step. The manufacturing method of the optical element of Claim 1 provided with the 2nd cutting process to perform.   The method of manufacturing an optical element according to claim 2, wherein the second cutting step and the ridge line processing step are simultaneously performed.   The method for manufacturing an optical element according to any one of claims 1 to 3, wherein, in the ridge line processing step, a ridge line portion of the optical element is cut into a chamfered shape.   The method for manufacturing an optical element according to claim 4, wherein the chamfered shape is one of a square chamfered shape and an R chamfered shape.   The method of manufacturing an optical element according to claim 5, wherein an inclination angle of the chamfered shape is 30 degrees or more and 60 degrees or less.   7. The multi-wavelength compatible lens according to claim 1, wherein the optical element is a multi-wavelength compatible lens having an optical path difference providing structure including a plurality of steps on at least a part of an optical function surface provided in an optical unit. A method for producing an optical element according to claim 1.   The method for manufacturing an optical element according to any one of claims 1 to 7, wherein at least one of excision and cutting is performed using an end mill in the target part cutting step and the ridge line processing step. . An optical unit having an optical functional surface;
An outer periphery provided around the optical part;
With
An optical element, wherein a ridge line processing portion of a cut trace of the gate portion formed on the outer peripheral portion has a chamfered shape.   The optical element according to claim 9, wherein the chamfered shape is one of a square chamfered shape and an R chamfered shape.   The optical element according to claim 10, wherein an inclination angle of the chamfered shape is 30 degrees or more and 60 degrees or less.   12. The optical element according to claim 9, wherein the optical unit has an optical path difference providing structure including a plurality of steps on at least a part of the optical function surface.   The ridge line machining unit includes the ridge line machining part provided in the cut trace of the gate part in the outer peripheral part, and the molding chamfered part provided in a region excluding the cut trace of the gate part in the outer peripheral part. The optical element according to claim 9, wherein the portion is smaller than the molded chamfered portion. The optical element according to any one of claims 9 to 13 is an objective lens for an optical pickup, and the following formula: 0.9 ≦ d / f ≦ 1.8
Objective lens characterized by satisfying
here,
d: Thickness on the optical axis of the objective lens (mm)
f: Focal length (mm) of the objective lens in the light flux with wavelength λ1

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