WO2008023578A1 - Optical element, method for manufacturing optical element, and optical head - Google Patents

Abstract

This invention provides an optical element which has good accuracy, light weight and good mass productivity. The optical element to be mounted on a slider which is moved on a recording medium is characterized in that the optical element is formed by injection molding by a mold having an reversed shape of the optical element using a resin, which is transparent to light guided from a light source, as a material, the optical element has a groove, one end of which is open and the other end is closed, and a deflection face for deflecting the above light introduced from the other end of the groove, and the mold is provided with a gate, into which the resin is poured, on its face in which the face, which is not the deflection face, is formed.

Description

 Specification

 Optical element, optical element manufacturing method, and optical head

 Technical field

 The present invention relates to an optical element, an optical element manufacturing method, and an optical head.

 Background art

 In the magnetic recording system, as the recording density increases, the magnetic bit is significantly affected by the external temperature and the like. Therefore, a force that requires a recording medium having a high coercive force. When such a recording medium is used, the magnetic field required for recording also increases. The magnetic field generated by the recording head is a force S whose upper limit is determined by the saturation magnetic flux density, and its value is approaching the material limit, so a dramatic increase cannot be expected. Therefore, local recording is heated during recording to cause magnetic softening, recording is performed in a state where the coercive force is small, and then the heating is stopped and natural cooling is performed to guarantee the stability of the recorded magnetic bit. A method has been proposed. This method is called a heat-assisted magnetic recording method!

 [0003] In the heat-assisted magnetic recording system, it is desirable to instantaneously heat the recording medium! Also, the heating mechanism and the recording medium are not allowed to come into contact. For this reason, heating is generally performed using light absorption, and a method using light for heating is called a light assist type.

 [0004] When ultra-high-density recording is performed with the optical assist method, the required spot diameter is about 20 nm. Since a normal optical system has a diffraction limit, light cannot be condensed to that extent.

 Therefore, near-field optical heads that use near-field light generated from an optical aperture having a size equal to or smaller than the incident light wavelength are used.

[0006] As an example of the near-field optical head, there is a near-field optical head including a mirror substrate, an aperture substrate, and an optical fiber. The mirror substrate has a mirror surface with A1 deposited on the slope formed by anisotropic etching on the Si substrate. A V-groove is formed in the mirror substrate by etching, and an optical fiber is fixedly bonded to it. The aperture substrate also has SiO force, and a microlens with a diameter of 0.2 mm is formed on the top surface. On the bottom surface of the aperture substrate, a slider for flying air is formed, and a near-field near-field light generating microstructure is formed between them. . The emitted light from the optical fiber is reflected by the mirror surface, condensed by the microlens, and applied to the near-field light generating microstructure (see Patent Document 1).

[0007] Further, as an example in which the optical waveguide and the optical fiber are connected optically and mechanically instead of the microlens in the above example, the position of the optical fiber to be optically coupled to the optical waveguide is determined. A V-groove member made of a transparent thermosetting or thermoplastic plastic with a V-shaped groove formed by transferring the V-shaped groove provided on the mold. An optical fiber bonded and fixed in a V-shaped groove, and a transparent plate-shaped member bonded and fixed thereon, and having a butt end surface for connecting to the optical waveguide substrate having the optical waveguide There are optical fiber alignment parts (see Patent Document 2).

 Patent Document 1: Japanese Unexamined Patent Publication No. 2003-6913

 Patent Document 2: JP-A-9 152522

 Disclosure of the invention

 Problems to be solved by the invention

 [0008] However, according to Patent Document 1, the mirror substrate has a slope formed by anisotropic etching on the Si substrate, and A1 is deposited to form a mirror surface, and the optical fiber is fixedly bonded. V-grooves are still formed by etching. Therefore, the V-groove to which the optical fiber 1 is fixed and bonded and the mirror surface for deflecting the light from the optical fiber 1 are formed as a body, but the formation process is complicated and the obtained mirror substrate Because it is made of Si, it is twice as heavy as plastic, and it is not advantageous for air levitation.

 [0009] Also, according to Patent Document 2, a V-shaped groove is used as an optical fiber aligning part for connecting a multi-core optical fiber together with an optical waveguide substrate, and a fine V-shaped groove is formed. This is a method of transferring the mold that we have to the plastic, which is simple in shape, essentially having fine V-shaped grooves formed on the surface of the flat plate, heat shrinkage is relatively uniform, and residual strain Because there is too little! /, The force S is described as being able to obtain a V-groove member with high forming accuracy, and the specific content for increasing the forming accuracy is described! /, Nare.

[0010] Further, in recent years, with the progress of high-density information recording in recording devices such as HDD (HARD DISK DRIVE), it is desired to reduce the size of the head that performs reproduction recording and the size of the slider that constitutes the head. ing. The size of the slider is the International Disk Drives Association (IDEMA, I NTERNATIONAL DISK DRIVE EQUIPMENT AND MATERIALS ASS OCIATION) Standardized as standard! In order of size! /, In order, they are named mini-slider, micro-slider, nano-slider, pico-slider and femto-slider. Among these sliders, the sliders currently attracting attention in terms of size are the nano-slider, pico slider, and femto slider. Table 1 shows the size (size) and mass of these sliders.

 [table 1]

[0012] In high-density information recording, the information on a single disk is of course increased in density so that the magnitude of the slider is also divided, and the disks are arranged in multiple layers, or as small as possible. It is also necessary to increase the spatial density by storing in the housing. For example, assuming a multi-layer disk arrangement, the distance between the disks is required to be as small as possible, and the thickness of the optical head including the slider thickness shown in Table 1 should be about 1.5 mm or less. Is desired.

 [0013] The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an optical element that is accurate, lightweight, and easy to manufacture, a method for manufacturing the optical element, and the optical element. It is to provide an optical head used.

 Means for solving the problem

[0014] The above problem is solved by the following configuration.

 [0015] 1. In an optical element mounted on a slider that moves on a recording medium,

A groove that is formed by injection molding using a mold having a reversal shape of the optical element using a resin that transmits light guided from a light source as a material, and one end is opened and the other end is closed. A gate for injecting the resin into a surface of the mold that forms a surface that is not the deflection surface. An optical element formed by using the mold.

[0016] 2. In addition to the deflection surface, the resin is formed on a surface of the mold that forms a surface that is neither the surface on which the groove is opened nor the surface opposite to the surface on which the groove is opened. 2. The optical element according to 1, wherein the optical element is molded using the mold having a gate into which is injected.

[0017] 3. In addition to the surface on the opposite side of the deflection surface, the groove opening! /, And the groove opening! /, The surface of the opening of the groove 3. The optical element according to 2, wherein the optical element is molded using the mold including a gate into which the resin is injected on a surface of the mold that forms a surface that is not any of the above.

[0018] 4. The optical element according to any one of 1 to 3, wherein the resin forming the bottom of the groove is thicker on the other end side than on the one end side.

[0019] 5. The optical element according to any one of 1 to 4, wherein a depth of the groove is shallower on the other end side than on the one end side.

[0020] 6. The optical element according to any one of 1 to 5, wherein the thickness of the optical element is 0.1 mm or more and 1 mm or less and satisfies the following conditional expression.

 b <L ≤ k X b

 c <W ≤ k X c

 However,

 k = 2: coefficient

 b: Length of the slider on which the optical element is placed in the same direction as the slider moves

 c: Width of the slider on which the optical element is placed in the direction perpendicular to the direction in which the slider moves

 L: Length of optical element in the same direction as b

 W: Width of optical element in the same direction as c

 7. The optical element according to any one of 1 to 6, wherein a condensing element for condensing light guided from the light source is fixed in the groove.

[0021] 8. The optical element according to 7, wherein the condensing element is fixed to a bottom of the groove.

[0022] 9. The optical element according to 7 or 8, wherein the condensing element is a gradient index lens coupled to a linear light guide that guides light from the light source. [0023] 10. An optical head comprising: the optical element according to any one of 7 to 9; and the slider that holds the optical element.

[0024] 11. The slider is fixed to a surface of the optical element having the groove opening, and a suspension supporting the optical element is fixed to a surface opposite to the surface having the groove opening. The optical head according to 10.

 12. In the manufacturing method of the optical element mounted on the slider moving on the recording medium, the resin is guided from the light source and made of resin that transmits the light. One end is opened and the other end is closed. A mold having a reversal shape of the optical element having a groove and a deflecting surface for deflecting the light incident from the other end of the groove is provided on a surface of the mold that forms a surface that is not the deflecting surface. An optical element comprising: a step of injecting the resin from a gate and performing injection molding; and a step of releasing the optical element molded from the mold after the injection molding step. Manufacturing method.

 13. In addition to the deflection surface, the gate forms either the surface where the groove is open or the surface opposite to the surface where the groove is open! /. 13. The method for manufacturing an optical element according to 12, wherein the optical element is provided on the surface of the mold.

 14. In addition to the deflection surface, the surface where the groove is open, and the surface opposite to the surface where the groove is open, the gate has a surface which is not any of the surfaces where the groove is open. 14. The method for manufacturing an optical element according to 13, wherein the optical element is provided on a surface of the mold to be formed.

 15. The method of manufacturing an optical element according to any one of 12 to 14, wherein the resin forming the bottom of the groove is thicker on the other end side than on the one end side.

 16. The method of manufacturing an optical element according to any one of 12 to 15, wherein the depth of the groove is shallower on the other end side than on the one end side.

 17. The method for producing an optical element according to any one of 12 to 16, wherein the thickness of the optical element is 0.1 mm or more and 1 mm or less and satisfies the following conditional expression.

 b <L ≤ k X b

c <W ≤ k X c However,

 k = 2: coefficient

 b: Length of the slider on which the optical element is placed in the same direction as the slider moves c: Width of the slider on which the optical element is placed in the direction perpendicular to the slider moving direction

 L: Length of optical element in the same direction as b

 W: Width of optical element in the same direction as c

 The invention's effect

 [0025] According to the present invention, the optical element is formed by injection molding using a mold using resin as a material, and one end of the formed optical element is opened and the other end is closed. And a deflecting surface for deflecting light incident from the other end. In the mold for molding the optical element, a gate for injecting resin into the mold is provided on a mold surface that forms a surface that is not a deflection surface of the optical element.

 Therefore, since there is no gate for injecting resin on the mold surface that forms the deflection surface of the optical element, the deflection surface can be formed well, and the light incident on the deflection surface can be deflected well.

 [0027] Further, since the optical element has a groove that can fix the condensing element, the condensing element, for example, a gradient index lens is easily and accurately fixed to the groove. be able to.

 Accordingly, an optical head using the optical element having the above-described effects can be configured.

Accordingly, it is possible to provide an optical element with high accuracy, light weight, and good mass productivity, an optical element manufacturing method, and an optical head using the optical element.

 Brief Description of Drawings

 FIG. 1 is a diagram showing an example of an optical recording apparatus.

 FIG. 2 is a sectional view showing an example of an optically assisted magnetic recording head having a magnetic recording element in the optical head.

 FIG. 3 is a perspective view showing an example of an optical element included in the optical head.

 FIG. 4 is a cross-sectional view showing an example of the configuration of an optical head.

 FIG. 5 is a perspective view showing an example of an optical element included in the optical head.

FIG. 6 is a cross-sectional view showing an example of the configuration of an optical head. FIG. 7 is a perspective view showing an example of an optical element included in the optical head.

 FIG. 8 is a perspective view showing a space filled with resin and a gate filled with resin when a mold for molding an optical element is closed.

 FIG. 9 is a diagram showing an example of an optical waveguide.

 FIG. 10 is a diagram showing an example of a plasmon probe.

 FIG. 11 is a perspective view showing a space filled with resin and a gate filled with resin when a mold for molding an optical element is closed.

 FIG. 12 is a diagram schematically showing how an optical element is attached to a slider.

 FIG. 13 is a perspective view showing a space filled with resin and a gate filled with resin when a mold for molding an optical element is closed.

 FIG. 14 is a perspective view showing a space filled with resin and a gate filled with resin when a mold for molding an optical element is closed.

 FIG. 15 is a view showing a surface where a V groove of an optical element is open.

 FIG. 16 is a perspective view showing a space filled with resin and a gate filled with resin when a mold for molding an optical element is closed.

 FIG. 17 is a perspective view showing a space filled with resin and a gate filled with resin when a mold for molding an optical element is closed.

 FIG. 18 is a perspective view showing a space filled with resin and a gate filled with resin when a mold for molding an optical element is closed.

 FIG. 19 is a perspective view showing a mold for molding an optical element.

Explanation of symbols

 2 discs

 3 Optical head

 4 Suspension

 11 Optical fiber (Linear light guide)

 12, 13 Gradient index lens (GRIN lens)

 14 Optical elements

14a Deflection surface 14b V groove

 15 Slider

 16 Optical assist part (optical waveguide)

 17 Magnetic recording unit

 18 Magnetic playback unit

 fO virtual light source

 fl face 1

 f2 side 2

 f3 face 3

 f4 side 4

 BEST MODE FOR CARRYING OUT THE INVENTION

 [0032] Hereinafter, the present invention will be described based on an optically assisted magnetic recording head having a magnetic recording element in the optical head according to the illustrated embodiment and an optical recording apparatus including the same. The present invention is not limited to this embodiment. In addition, the same code | symbol and mutual equivalent part of each embodiment are attached | subjected the same code | symbol, and duplication description is abbreviate | omitted suitably.

 FIG. 1 shows a schematic configuration example of an optical recording apparatus (for example, a node disk apparatus) equipped with an optically assisted magnetic recording head (hereinafter referred to as an optical head). This optical recording apparatus 1A includes a recording disk (magnetic recording medium) 2, a suspension 4 provided so as to be rotatable in the direction of arrow A (tracking direction) with a support shaft 5 as a fulcrum, and attached to the suspension 4. The housing 1 is provided with a tracking actuator 6, an optical head 3 attached to the tip of the suspension 4, and a motor (not shown) that rotates the disk 2 in the direction of arrow B. The head 3 is configured to move relative to the disk 2 while floating.

FIG. 2 is a sectional view showing an example of the optical head 3. The optical head 3 is an optical head that uses light for information recording on the disk 2, and is an optical fiber 11 that is a linear light guide that guides light to the optical head 3, and a recording portion of the disk 2. Optical assist part (optical waveguide) 16 for spot heating with near-infrared laser light and refractive index distribution that is a condensing element that guides the near-infrared laser beam emitted from the optical fiber 11 to the optical assist part 16 Mold lenses 12, 13 and light The optical element 14 having a deflecting surface 14a which is a path deflecting means, the optical waveguide 16 and the magnetic recording unit 17 for writing magnetic information to the recording part of the disk 2 and the disk 2 are recorded. A slider 15 having a magnetic reproducing unit 18 for reading magnetic information is provided.

 The optical element 14 is provided with a V-shaped groove (hereinafter referred to as a V-groove) for fixing and bonding the optical fiber 11 and the gradient index lenses 12 and 13 that are condensing elements. ing. The V groove has a structure in which the thickness of the resin forming the bottom is thicker on the closed side than on the open side of the V groove. Figure 3 shows the optical element 14 in a perspective view, where 14b is V?冓, 14a indicates the deflection surface.

 In FIG. 2, the magnetic reproducing section 18, the optical waveguide 16, and the magnetic recording section 17 are arranged in this order from the entry side to the exit side (→ direction in the figure) of the recording area of the disk 2. The order is not limited to this. Since the magnetic recording unit 17 may be located immediately after the exit side of the optical waveguide 16, for example, the waveguide 16, the magnetic recording unit 17 and the magnetic reproducing unit 18 may be arranged in this order.

 The light guided by the optical fiber 11 1 is, for example, light emitted from a semiconductor laser, and the wavelength of the light is a near infrared wavelength of 1.2 m or more (as a near infrared band) 0.8 μΐη to about 2 m, and specific laser light wavelengths include 1310 nm, 1550 nm and the like S). Near-infrared laser light emitted from the end face of the optical fiber 11 1 is guided to an optical waveguide provided on the slider 15 by an optical element 14 having a gradient index lens 12, 13 and a deflecting surface 14a. The light is condensed on the upper surface of 16 and guided through the optical waveguide 16 constituting the optical assist portion, and emitted from the optical head 3 toward the disk 2.

[0038] The slider 15 moves relative to the disk 2 as a magnetic recording medium while flying, but there is a possibility of contact if there is dust attached to the medium or the medium is defective. In order to reduce the wear that occurs in this case, it is desirable to use a hard and highly wear resistant material for the slider. For example, a ceramic material containing A10, for example, AlTiC, zirconia, or TiN may be used. Further, as a wear preventing treatment, a surface treatment may be performed on the surface of the slider 15 on the disk 2 side in order to increase the wear resistance. For example, when a DLC (DIAMOND LIKE CARBON) film is used, hardness of Hv = 3000 or higher can be obtained after a diamond having a high transmittance of near infrared light. [0039] Further, the surface of the slider 15 facing the disk 2 has an air bearing surface (also referred to as an ABS (AIR BEARING SURFACE) surface) for improving the flying characteristics. The slider 15 needs to be stabilized in the state of being close to the disk 2, and it is necessary to appropriately apply pressure to the slider 15 to suppress the flying force. Therefore, the suspension 4 fixed on the optical element 14 has a function of appropriately applying a pressure for suppressing the flying force of the slider 15 in addition to the function of tracking the optical head 3.

 [0040] When the near-infrared laser beam emitted from the optical head 3 is irradiated to the disk 2 as a minute spot, the temperature of the irradiated part of the disk 2 temporarily rises and the holding power of the disk 2 decreases. To do. Magnetic information is written by the magnetic recording unit 17 to the irradiated portion in which the holding force is reduced. The optical head 3 will be described below.

 First, the gradient index lenses 12 and 13 constituting the light condensing element will be described. A refractive index distributed lens (GRADED INDEX LENS, hereinafter abbreviated as “GRIN lens”) uses a medium with a uniform refractive index (closer to the center! /, The higher the refractive index). It is a cylindrical lens that acts as a lens by changing the refractive index continuously. Specific GRIN lenses include, for example, SiGRIN (registered trademark) (Silica Darin, Toyo Glass Co., Ltd.).

 The refractive index distribution n (r) in the radial direction of the GRIN lens is expressed by the following equation (1).

n (r) = N0 + NR2 X r ² (1)

 However,

 n (r): Refractive index at a distance r from the center

 NO: Refractive index at the center

 NR2: Constant that expresses the focusing ability of the GRIN lens

The GRIN lens has a feature that it is easy to align the optical axis because it has a refractive index distribution in the radial direction. For this reason, the optical axes of the optical fiber 11, the GRIN lens 12, and the GRIN lens 13 can be easily aligned. In addition, when the optical fiber 11 is made of stone, the material forming the GRIN lens 12 and the GRIN lens 13 is the same as that of the optical fiber 11, so they can be joined and integrated by a melting process. . This bonding facilitates handling, and at the same time, reduces optical loss at the surface where the optical fiber 11, the GRIN lens 12, and the GRIN lens 13 are in contact with each other, and is guided by the optical fiber 11. Light can be efficiently emitted from the GRIN lens 13.

[0042] The light condensing element composed of the GRIN lens 12 and the GRIN lens 13 converges the light guided by the optical fiber 11 to a position away from the light exit surface of the GRIN lens 13 to form a light spot.

MERICAL APERTURE) is different, and the GRIN lens 12 and GRIN lens 13 are selected, combined, and the length of each is determined appropriately so that the length occupied by the optical element and the light spot from the light exit surface of the optical element The distance to the position can be determined.

It is more preferable than the force S that the diameters of the GRIN lens 12 and the GRIN lens 13 and the diameter of the optical fiber 11 are substantially the same, preferably about ± 10%. As described above, the optical fiber 11, the GRIN lens 12, and the GRIN lens 13 can be joined by melting processing. Touch with S.

 When the optical fiber 11, the GRIN lens 12, and the GRIN lens 13 are joined and integrated (hereinafter referred to as a combined condensing element), the light is guided from the light source by the fiber 11 and light is emitted from the exit end face of the GRIN lens 13. A light spot can be efficiently formed at a position distant from. This bonded condensing element is bonded and fixed along the bottom of the V ′ groove 14b provided in the optical element 14 shown in FIG. 3 and with the end face of the GRIN lens 13 in close contact with the closed end of the V groove. /! The V-groove 14b is provided in consideration of the diameter of the coupled condensing element to be fixed, the light emission position from the combined condensing element, the distance to the deflection surface 14a, the incident angle of the light from the condensing element, and the like. It has been. Therefore, as described above, the coupling condensing element can be fixed along the V-groove 14b, so that it can be assembled easily and accurately, and the light guided from the light source by the fiber 11 is the condensing element GRIN lens. 12 and the GRIN lens 13 can be used as convergent light, and the light flux can be deflected by the deflecting surface 14a, so that a light spot can be efficiently formed on the lower surface of the optical element 14.

[0045] Further, as described above, the optical head has a configuration in which the condensing element including the GRIN lenses 12 and 13 is provided between the optical fiber 11 and the deflection surface 14a, for example, the deflection angle on the deflection surface 14a. Is 90 °, the above-mentioned coupled condensing element can be provided in a direction substantially parallel to the direction in which the optical head 3 floats, and there is no need to dispose the condensing element in the height direction of the optical head. The optical head can be made thin, and the optical head can be miniaturized. The optical element 14 is formed by an injection molding method using a thermoplastic resin as a material. For example, Si, which is good at fine processing, can be processed by photolithography and etching to obtain the same shape as the optical element 14, but the manufacturing process is complicated due to the same power as the semiconductor manufacturing process. Mass is heavier than resin.

 [0047] By using a thermoplastic resin instead of Si as a material, a light optical element 14 can be obtained using an injection molding method with good mass productivity. Also, by using resin molding, the degree of freedom of shape is higher compared to Si processing by photolithography processing and etching processing, and it is easy to set V groove shape, groove inclination, reflection surface angle etc. appropriately It can be obtained by processing. Examples of such thermoplastic resins that can be injection-molded include ZEONEX (registered trademark) 480R (refractive index 1 · 525, Nippon Zeon Co., Ltd.), PMMA (polymethylmetatalylate, such as Sumipex ( (Registered trademark) MGSS, refractive index 1 · 49, Sumitomo Chemical Co., Ltd.), PC (polycarbonate, eg Panlite (registered trademark) AD5503, refractive index 1.585, Teijin Chemicals Ltd.) .

 [0048] When the optical element 14 is manufactured by the injection molding method using the thermoplastic resin mentioned in the above example, the surface that requires optical accuracy is the deflection surface 14a. For example, when a deformation such as surface distortion or undulation occurs on the surface of the deflecting surface 14a, the light flux incident and deflected on the deflecting surface 14a is not uniformly converged. For this reason, a light spot with good incident efficiency cannot be formed on the incident surface of the optical waveguide 16 provided on the lower surface of the optical element 14. The inventors have energetically studied the above-described minute optical element 14 having an optically good surface shape. As a result, an optical element having a good deflection surface 14a has been obtained. This will be explained below.

 [0049] When the optical element 14 is molded by injection molding using a resin as a material, a gate that is a resin injection port in a mold used for molding is provided on a mold surface that forms a surface that is not the deflection surface 14a. As an example of this, FIG. 8 is a perspective view showing a space (cavity) filled with a resin in a state where a mold for molding the optical element 14 is closed and a gate filled with the resin.

FIG. 19 shows an example of a mold provided with an inverted space (cavity) of the optical element 14 shown in FIG. 8 and a resin filling gate. Ml indicates the first mold, M2 indicates the second near mold, and the optical element 14 is molded by injecting resin from the gate G1 with the two molds closed. It is. In the first mold Ml, Ml-1 is the surface that forms the deflection surface 14a, Ml-2 and M1-3 are the surface 14f-2 and 14f-3, respectively, 1-4 is the surface 146, Ml — 5 is the surface that forms surface 14c. In the second mold M2, M2-1 is V?冓 14b, M2-2 is the surface that forms surface 14d.

 [0051] The optical element 14 has a very small size, for example, Imm X lmm and a thickness of about 0.5 mm. Further, an example different from FIG. 8 is shown in FIGS. 13 and 14 in which the gate of the mold for molding the optical element 14 is provided on the mold surface forming the surface that is not the deflection surface 14a.

 In FIG. 8, the deflecting surface 14 a of the optical element 14, V?面 The surface 14d where 14b is open 14d, V? A gate 14g is provided on the mold surface forming the surface 14f-1, which is neither the surface 14e opposite to the surface 14d where the ridge 14b is open or the surface 14c where the V 'groove 14b is open. In FIG. 13, the deflection surface 14a of the optical element 14, the surface 14d where the V-groove 14b is opened, and the surface 14e opposite to the surface 14d where the V-groove 14b is opened are V-groove 14b. A gate 14g is provided on the surface of the mold that forms the open surface 14c. In FIG. 14, the gate 14g is provided on the surface of the mold forming the surface 14e opposite to the surface 14d where the V-groove 14b is opened, which is not the deflection surface 14a of the optical element 14.

 [0053] A member formed by injection molding has large shape deformation and internal stress in the vicinity of the gate. This is because when the resin passes through the gate and enters the cavity inside the mold, the inflow area changes rapidly, and the pressure distribution of the inflowing resin changes abruptly. For this reason, birefringence occurs in the vicinity of the gate of the formed member even if the surface distortion causes disturbance of the light flux.

 [0054] Since the above-described characteristics that cause internal stress are inevitable in resin molding, when injection molding optical element 14, gate 14g is provided on a mold surface that forms a surface that is not deflection surface 14a. In FIG. 8, FIG. 13, and FIG. 14, the surface provided with the gate 14g of the mold that forms the optical element 14 is an optical surface because it is a mold surface that forms a surface that is not the deflection surface 14a. In the vicinity of the deflecting surface 14a, a large surface distortion does not cause birefringence, and the optical element 14 having good optical performance can be obtained.

[0055] In addition to the deflection surface 14a, the mold surface provided with the gate 14g is any of the surface 14d where the V-groove 14b is open and the surface 14e opposite to the surface 14d where the V-groove 14b is open. But the shape that is not The surface to be formed is preferable. This corresponds to the position of the gate 14g of the mold for molding the optical element 14 shown in FIG. 8 and FIG. Taking the optical element 14 shown in Fig. 8 as an example, if the surface that forms the surface 14d with the V-groove is provided with the gate 14g, the place where the gate 14g can be provided is the opposite V across the V-groove. There are a groove facing part and a light passing part through which the light deflected by the deflecting surface 14a passes. Fig. 15 shows the surface of the optical element 14 where the V-groove is open. In FIG. 15, 110 indicates a V-groove facing portion, and 120 indicates a light passage portion.

 [0056] Since the light passing portion 120 is an optical surface on which the light emitted from the coupling condensing element is collected, it is not preferable that the same surface distortion as in the case of the deflection surface 14a has birefringence. Further, the V-groove facing portion 110 is a surface to be bonded to the slider 15. Normally, the gate part is cut after molding, but it is difficult to cut it flat so that it is at the same height as the surface near the gate. Therefore, the gate part becomes larger (higher than the surrounding area) after molding and cutting, and high. It becomes difficult to adhere to the slider accurately. Therefore, it is preferable to provide a gate on the mold surface that forms a surface that is not the surface 14d where the V ′ groove 14b is open.

 [0057] In addition, when a gate is provided on the mold surface for molding the surface 14e opposite to the surface 14d where the V-groove 14b is open, the resin flowing into the mold is separated into two or more resin flows. In some cases, a so-called weld line is generated by joining again. The weld line is in the vicinity of it, and birefringence due to distortion and internal stress occurs, although not as much as near the gate. Therefore, as an optical element, the weld line should not be generated in important parts such as the deflection surface. Is preferred. It is preferable to provide a gate 14g on a mold surface for molding a surface that is not the surface 14e so that a weld line does not occur in the vicinity of the deflecting surface and the condensing surface. If there is a gate on the mold surface for molding the surface 14e, it is difficult to flatten the gate and it is difficult to make a good surface for bonding for the same reason as described above. Also from this point, it is preferable to provide the gate 14g on the mold surface for molding the surface that is not the surface 14e.

Yes

[0058] Further, the mold surface including the gate 14g is added to the surface 14e opposite to the deflection surface 14a, the surface 14d where the V 'groove 14b is opened, and the surface 14d where the V groove 14b is opened. V? More preferably, the ridge 14b is a surface that forms a surface that is not any of the open surfaces 14c. If there is a gate 14g on the mold surface that forms the surface 14c where the V-groove 14b is open, Weld lines that are expected to be light may occur near the deflection surface 14a.

Accordingly, as shown in FIG. 8, the deflection surface 14a, the surface 14d where the V-groove 14b is opened, the surface 14e opposite to the surface 14d where the V-groove 14b is opened, and the V′-groove 14b are opened. It is more preferable to provide a gate on the surface of the mold that forms the surface 14f1, which is not any of the surfaces 14c. The surface 14f1 is preferably the surface 14f2 as well.

 FIG. 16, FIG. 17, and FIG. 18 show optical elements 74, 84, and 94, respectively, as examples of optical elements that are configured with V-grooves different from the optical element 14 shown in FIG. 8, FIG. 13, and FIG. Each of these optical elements 74, 84, and 94 is provided with V grooves 74b, 84b, and 94b for fixing a refractive index distribution type lens that is a condensing element, with one end opened and the other end closed. Yes. Further, deflecting surfaces 74a, 84a, 94a for deflecting light incident from the closed end faces of the V ′ grooves 74b, 84b, 94b are provided. The V groove 74b of the optical element 74 shown in FIG. 16 has a constant thickness at the bottom of the V groove. The V-groove 84b of the optical element 84 shown in FIG. 17 has an open V-groove on the surface opposite to the surface on which the slider is attached, and the thickness of the bottom of the V-groove is constant. Also, V of the optical element 94 shown in FIG.冓 94b has a V-groove on the opposite side of the slider mounting surface. The bottom of the V-groove is thicker at the open end of the groove and thinner at the other end.

 [0061] In the mold used when all of these optical elements 74, 84, and 94 are manufactured by injection molding, the gate for injecting the resin is a mold that molds a surface other than the deflection surfaces 74a, 84a, and 94a. It is prepared on the mold surface. Also, the deflection surfaces 74a, 84a, 94a, the grooved surfaces 74d, 84e, 94e, and the groove surface are open and the opposite surface of the lj surface 74e, 84d, 94d N! /, The mold surface forming the surface is preferred. Further, deflection surfaces 74a, 84a, 94a, surfaces 74d, 84e, 94e with grooves open, surfaces 74e, 84d, 94d opposite to the surfaces with grooves open, surfaces 74c with grooves open, More preferably, the surface that is neither 84c nor 94c is a mold surface to be molded. Fig. 6, Fig. 17, Fig. 18 (The gates 74g, 84g, 84g of the molds for molding the optical elements 74, 84, 94 are the surfaces 74f-1, 84f-l which are the preferred positions described above. In this way, the optical surfaces, in particular, the deflection surfaces 74a, 84a, 94a are formed satisfactorily like the optical element 14.

[0062] The positions of the V-grooves of the optical elements 84 and 94 shown in Figs. The relationship with the position where the lid is provided is opposite to the relationship with the position in the optical element 14 shown in FIG. However, since there is no change in the positional relationship between the occurrence of the weld line and the increase in the gate portion after forming and cutting, the optical elements 84 and 94 should be considered in the same manner as described above. Can do.

 Next, when the optical element 14 having the reflecting surface 14a and the V-groove 14b shown in FIG. 3 is molded using the thermoplastic resin raised in the above example, as shown in FIG. Thickness force of bottom of V-groove 14b for fixing element It is preferable that the closed side is thicker than the open side of V-groove 14b. As shown in FIG. 3, when the top surface of the optical element 14 is flat, the depth force of the V-groove 14b V is closed! .

 [0064] Generally, in resin molding by injection molding, in addition to suppressing the distortion and internal stress of the filled resin such as the vicinity of the gate and the well line described above, gaps are formed in every corner of the mold. It is important to fully fill the resin without it occurring. However, the smaller the space (cavity) formed by the mold, the smaller the cross-sectional area through which the resin can flow, and it becomes more difficult to fill the resin without generating a gap.

 [0065] As already described, the optical element 14 according to the present invention has a size of, for example, lmm.

 X lmm, thickness is as small as 0.5mm. The inventors have energetically studied the configuration of such a small optical element that has no surface in which the resin is not filled and the surface shape is optically good. The force S was obtained to obtain an optical element that did not cause poor filling.

 Specifically, as shown in FIG. 3, the thickness of the resin forming the bottom of the V ′ groove 14b is made thicker on the closed side than on the opened side of the V groove 14b. By configuring in this way, V? V V along 14b?に お い て In the bottom cross section of 14b, V?断面 The cross-sectional area of the closed side can be increased from the open side of 14b, and the cross-sectional area is large, which reduces the resistance to resin flow and makes it easy for the resin to flow .

[0067] The portion where the thickness of the resin is reduced may cause insufficient filling of the resin or insufficient pressure when the resin is injected, and as a result, the distortion causing optical birefringence increases, and the surface accuracy is insufficient. Problems arise. The problem tends to concentrate near the thinnest part of the resin, so from the point of view of accuracy, the part that requires high accuracy is the thinnest resin. It is necessary to consider not to be close to the part. Therefore, the closed side of the optical element 14 is thicker than the open side of the V-groove 14b so that the V-groove is closed when the optical element 14 is formed! The optical element 14 having good optical characteristics can be obtained by sufficiently securing the fluidity of the resin around the periphery of 14a.

 [0068] The thickness force of the resin forming the bottom of the V-groove As an example of a configuration in which the closed side is thicker than the open side of the V-groove, the upper surface of the optical element 14 is as shown in FIG. In the case of flatness, the V groove 14b is inclined, and, for example, as shown in FIG. 4, the optical head 40 (FIG. 5 shows a perspective view of the optical element 44).と し て The top surface of the optical element 44 is V? ？ As shown in Fig. 6 (Figure 7 shows a perspective view of the optical element 64), V? V The top surface of the optical element 64 is V? The side where the flange 64b is closed can be raised one step further, or the V ′ groove 64b can be inclined and the upper surface of the optical element 64 can be inclined or a step can be provided.

 [0069] Further, as shown in FIG. 2, when the upper surface of the optical element is substantially parallel to the upper surface of the disk 2, the incident angle to the deflecting surface 14a is provided because the V-groove for fixing the coupling condensing element is provided obliquely. Can increase the power S. The resin constituting the optical element 14 has a low refractive index of about 1.5 as compared with an optical glass having a high refractive index of about 1.7, so that the total reflection angle on the deflecting surface 14a is large. For example, when the resin constituting the optical element is ZEONEX (registered trademark) having a refractive index of 1.525, the total reflection angle is about 42 degrees. When the light deflection angle by the deflecting surface 14a is 90 ° (incident angle to the deflecting surface 45 °), the light beam is totally reflected if a converging light beam within ± 3 degrees is incident, but it has a larger incident angle width. In this case, light that does not reflect and passes through the deflecting surface 14a and leaks to the outside is generated, so that the reflection efficiency decreases. Therefore, the incident angle to the deflecting surface 14a can be increased by making the V-groove for fixing the coupling condensing element oblique, and the total reflection can be facilitated. For example, as shown in Fig. 2, when the V-groove is tilted 10 °, the incident angle on the deflecting surface 14a is 50 °, so there is a margin of 8 ° until 42 ° where total reflection occurs. It is possible to achieve total reflection for a wider luminous flux width of the light to be reflected, and to increase the reflection efficiency.

Further, when the refractive index of the resin constituting the optical element 14 is increased, the light emitted from the optical element 14 can be more efficiently guided to the optical waveguide 16. The light emitted from the coupling condensing element is The light is incident on an optical element made of grease and is deflected by the deflection surface to form a light spot on the lower surface of the optical element. If the full incident angle of the light beam that forms this light spot is Θ, the NA of the light beam that forms the light spot is given by the following equation (2).

 NA = nsin Θ (2)

 However,

 n: Refractive index of the resin constituting the optical element

 Θ: Full incident angle of light beam forming light spot

 It is. As shown in the above equation (2), NA becomes larger by multiplying by about n (refractive index) compared to the case where the medium through which the light beam forming the light spot passes is air, and therefore the formed optical beam is formed. Can reduce the pot diameter. Therefore, the light emitted from the optical element 14 to the optical waveguide 16 can be guided to the optical waveguide 16 more efficiently.

 As shown in FIG. 2, the V ′ groove 14b for fixing the coupled condensing element is opened to the lower surface side of the optical element 14, and the coupled condensing element is fixed to the upper side which is the bottom of the V groove 14b. It is preferable to do this. The optical head 3 must hold it on the disk 2 and, for example, be coupled to the suspension 4. It is necessary to secure a place for coupling with the suspension 4 in the optical head 3. The configuration in which the optical head 3 is held from the lower side is difficult because the slider 15 having a floating mechanism that floats on the disk 2 and moves relative to the disk 2 is necessary. The configuration in which the suspension 4 is provided so as to be sandwiched between the optical element 14 and the slider 15 is V for holding the combined condensing element. It is necessary to avoid opening this V 'groove 14b due to the presence of 冓 14b. Also, it is necessary to avoid the light beam condensed on the optical waveguide 16. For this reason, for example, when the suspension 4 is to be fixed in the direction of relative movement on the recording surface and at the center of the optical element 14, the location where the suspension 4 is fixed is V?中央 Since it cannot be the center of the optical element 14 along the line 14b, it is difficult to maintain a good balance.

 Accordingly, when the coupled condensing element is held from the upper side of the optical element 14, the optical element

The upper surface of 14 can be the position where the suspension 4 is fixed. The top surface of the optical element 14 is a flat surface free of irregularities such as V-grooves, so that the optical head 3 having a high degree of freedom in mounting the suspension 4 can be stably floated on the disk 2. The suspension 4 can be fixed to the optical element 14 with a good balance. Also, using the plane state For example, a positioning mark for coupling to the suspension 4 that facilitates assembly can be provided on the upper surface of the optical element 14. In addition, since the suspension 4 and the optical fiber 11 that guides light from the light source are close to each other, the optical fiber 11 can be easily fixed along the suspension 4.

[0073] The thickness of the optical element 14 is preferably not less than 0.1 mm and not more than lmm. By making the thickness within this range, it is possible to fill the mold with resin sufficiently, and the thickness of the bottom of the V-groove is good by making the closed end thicker than the open end It is possible to obtain an effect that enables easy molding. The size of the optical element 14 in the direction perpendicular to the thickness direction (length L, width W) corresponds to the size of the slider (length b, width c) on which the optical element shown in Table 1 is mounted. Thus, it is preferable that conditional expressions (3a) and (3b) are satisfied.

 b <L ≤ <k X b (3a)

 c <W ≤ k X c (3b)

 However,

 k = 2: coefficient

 b: Length of the slider on which the optical element is placed in the same direction as the slider moves

 c: Width of the slider on which the optical element is placed in a direction perpendicular to the direction in which the slider moves

 L: Length of optical element in the same direction as b

 W: Width of optical element in the same direction as c

 It is.

 [0074] As shown in FIG. 8, when a gate is provided on the surface of the mold for molding the surfaces 14f1, 14f2 of the optical element 14, an eject for removing the molded optical element 14 from the mold is performed. A pin may be provided on the surface 14e side. In this case, the position where the eject pin is provided usually depends on the position perpendicular to the gate and the position where the V groove of the optical element 14 is located.

[0075] Further, as a method of releasing the optical element 14 from the mold, there is a method called core pressing, which is performed by pressing a shape portion (core) of the mold instead of the eject pin. Regardless of whether the core is pushed or ejected, there is a slight gap in the movable part because there is a movable part on the molding surface of the mold. Resin may enter the gap of the mold, and the resin that enters the gap is transferred to the optical element as a shape called a burr. [0076] When the optical element 14 is molded with such a mold configuration, there is a case in which the periphery of the lower surface of the optical element 14 is generated. When burrs are generated on the lower surface of the optical element 14, there is a projection on the mounting surface when the optical element 14 is attached to the slider 15. When the size of the surface on which the optical element 14 can be attached to the slider 15 is the same as or smaller than the mounting surface of the slider 15, the adhesive surface between the optical element 14 and the slider 15 floats or tilts.

 This situation is shown in FIG. 20 indicates a burr. FIG. 12A shows a case where the width W 1 of the optical element 14 is larger than the width c of the slider 15. In this case, the optical element 14 can be satisfactorily attached to the slider 15. 12B and 12C show a case where the width W2 of the optical element 14 is smaller than the width c of the slider 15. FIG. In this case, the optical element 14 and the slider 15 are attached in a floating or tilted state. Therefore, it is preferable to make the size of the optical element 14 larger than the size of the slider 15 because the slider 15 can be accurately attached to the lower surface of the optical element 14 without removing burrs.

 [0078] Further, the force that can be reduced by molding the optical element 14 with a resin. The specific gravity of Si is about 2.4, and the specific gravity of the resin is about 1 (for example, ZEONEX (registered trademark) 480R (Nippon Zeon ( )) Has a specific gravity of 1.04 (catalog value).)) If the force due to the thickness of the optical element 14 is too large, the function is equivalent to that of the optical element 14 formed of Si. It becomes lighter than the mass of an optical element made of Si. For example, the size of an optical element made of ZEONEX (registered trademark) 480R that has the same mass as an optical element made of Si with the same thickness (assumed to be square) is ZEONEX when the optical element made of Si is 1. The optical element made of (registered trademark) 480 R is about 1.4. Therefore, the coefficient k in the conditional expressions (3a) and (3b) that define the upper limit of the size is set to 2, preferably 1 · 5, more preferably 1 · 2.

 Therefore, the size (length L, width W) of the optical element 14 in the direction perpendicular to the thickness direction is expressed by the conditional expression (

 By satisfying 3a) and (3b), an optical element that is lightweight and easy to assemble can be obtained with the force S.

 [0080] The position where the light spot is formed by the condensing element consisting of the GRIN lenses 12 and 13 is set to the slider.

It is preferable that the optical waveguide 16 is provided directly below the upper surface of 15. By providing the optical waveguide 16, the light spot that converges on the upper surface of the slider 15 can be efficiently guided to the lower surface of the slider 15 without impairing the spot diameter. Light that converges on the optical waveguide 16 The direction is preferably substantially perpendicular to the incident surface of the optical waveguide 15. The efficiency of light guiding through the optical waveguide 16 becomes worse as it is tilted from the vertical direction. When it is tilted by about 30 °, it is hardly guided, and light can be guided efficiently by setting it to be approximately ± 10 °.

 [0081] Further, since it is not necessary to pass the converging light having an angle through the inside of the slider 15, the magnetic recording unit 17 and the magnetic recording unit 17 and the optical recording medium 16 are located at positions close to the front and rear of the optical waveguide 16 in the direction in which the magnetic recording surface relatively moves. The magnetic reproducing unit 18 can be easily provided.

 [0082] Further, by providing the optical waveguide 16 with an optical spot size conversion function to be described later, the optical waveguide

 The force S can be reduced by making the diameter of the light spot formed on the 16 incident surface smaller at the exit surface than the diameter at the incident surface of the optical waveguide 16. Therefore, the force S for forming a smaller light spot diameter on the surface of the recording medium can be achieved, and the recording density can be increased.

 FIG. 9 shows an example of an optical waveguide having a light spot size conversion function. 9A and 9B show the state of the optical waveguide viewed from the direction in which the optical head moves relatively, and FIG. 9C shows the magnetic recording surface perpendicular to the moving direction. The view from the parallel direction is schematically shown. The optical waveguide shown in FIG. 9 includes a core 16a (for example, Si), a sub-core 16b (for example, SiON), and a clad 16c (for example, SiO 2). As shown in FIG. 9C, a plasmon probe 16f for generating near-field light is disposed at or near the light emission position of the optical waveguide. A specific example of the plasmon probe 16f is shown in FIG.

[0084] In FIG. 10, (A) is a plasmon probe 16f made of a triangular flat metal thin film (material examples: aluminum, gold, silver, etc.), and (B) is a bow-tie flat metal thin film (material example: a The plasmon probe 16f is composed of an antenna having an apex P with a radius of curvature of 20 nm or less. (C) is a plasmon probe 16f made of a flat metal thin film (material examples: aluminum, gold, silver, etc.) having an opening, which is composed of an antenna having a vertex P with a radius of curvature of 20 nm or less! /, The When light acts on these plasmon probes 16f, near-field light is generated in the vicinity of the apex P, and recording or reproduction using light with a very small spot size can be performed. In other words, if a local plasmon is generated by providing the plasmon probe 16f at or near the light emission position of the optical waveguide, the size of the light spot formed by the optical waveguide can be reduced, and high density recording can be achieved. It will be advantageous. Note that the apex of the plasmon probe 16f is in the center of the core 16a. P is preferably located.

[0085] The spot diameter required for ultra-high-density recording with the optical assist method is about 20 nm. Considering the light utilization efficiency, the mode field (MFD) of the plasmon probe 16f is about 0.3 mm. desirable. Since this MFD size makes it difficult for light to enter, spot size conversion is necessary to reduce the spot diameter from about 5 Hm to several lOOnm.

[0086] In FIG. 9, the width of the core 16a is a constant force from the light input side to the light output side in the cross section shown in FIG. 9C. In the cross section shown in FIG. In Fig. 4, the width gradually increases from the light input side to the light output side. The mode field diameter is converted by the smooth change of the optical waveguide diameter. In other words, the width of the core 16a of the optical waveguide is 0 · m or less on the light input side and 0 · 3 111 on the light output side as shown in FIG. 9 (A). As shown in the figure, on the optical input side, an optical waveguide having an MFD of about 5 m is formed by the sub-core 16b, and thereafter, the mode field diameter can be reduced by gradually optically coupling to the core 16a. Thus, when the mode field diameter on the optical output side of the optical waveguide is d and the mode field diameter on the optical input side of the optical waveguide is D, the mode field diameter is converted by smoothly changing the optical waveguide diameter. Therefore, it is preferable to satisfy D> d.

 The optical head described so far is an optically assisted magnetic recording head that uses light for information recording on the disk 2, but is an optical head that uses light for information recording on a recording medium, and uses magnetic reproduction. For example, an optical head that performs recording such as near-field optical recording and phase change recording can be used, and the above-described plasmon probe 16f is used as the light emission of the optical waveguide 16. You may arrange | position in the position or its vicinity.

 Example

 [0088] Examples relating to the present invention will be described below.

[0089] Conditions common to Examples 1 to 5 shown below are shown below.

 Wavelength used: 1. 31 m

 Equation (1) indicating the refractive index of the GRIN lens is again shown below.

n (r) = NO + NR2 X r ² (1) However,

 r: Distance from the center (radial distance from the center)

 It is.

 [0090] The constants necessary to express the refractive index in GRIN lens A and GRIN lens B, which are the gradient index lenses used in Examples 1 to 5 below, by the above equation (1) are as follows: Show.

 GRIN lens A

 NA = 0.166 (execution column 1 force, et al. 4), 0.156 (execution column 5)

 N0 = 1. 479606

 NR2 = — 2. 380952

 GRIN lens B

 NA = 0.395 (execution column 1 force, et al. 4), 0.372 (execution column 5)

 N0 = 1. 540737

 NR2 =-12. 47619

 Diameter of GRIN lens A and GRIN lens B: 85 m (Examples 1, 2, and 4), 125 111 (Example 3), 80 ^ 111 (Example 5)

 Slider 15: Made of AlTiC, length (moving direction) 0 · 85mm, thickness (flying direction) 0 · 23mm, width (depth) 0.7mm.

 Diameter of optical fiber: 85 ^ 111 (Examples 1, 2, 4), 125 ^ 111 (Example 3), 80 ^ 111 (Example 5)

 In the following examples, the magnetic recording unit, the magnetic reproducing unit, and the plasmon probe are not provided. However, when an optically assisted magnetic recording head is used or when performing ultra-high density recording, it is necessary to provide them. It goes without saying that

[0091] The joint surface and the final end surface on the optical path in FIG. 2 and FIG. 6 are added with symbols starting with f0, fl, f2,. It corresponds to the virtual light source, surface 1, surface 2,... Of the surface items shown in the corresponding table.

[0092] (Example 1)

In FIG. 2, 3 is an optical head, 11 is an optical fiber, 12 is a GRIN lens (GRIN lens A ), 13 is a GRIN lens (GRIN lens B), 14 is an optical element in which a V-groove 14b inclined by 10 ° and a deflecting surface 14a are integrated, 15 is a slider, and 16 is an optical waveguide. A perspective view of the optical element 14 is shown in FIG. The optical element 14 injects molten resin (described later) into a mold (described later) having an inverted shape of the optical element 14 from a gate provided on a mold surface that forms a surface that is not a deflection surface. After the step of injection molding and the step of injection molding, after passing through the step of releasing the optical element molded from the mold, it was obtained by removing the gate trace.

 In FIG. 2, the optical element 14 provided with the V groove 14b on the slider 15 is bonded and fixed. The optical element 14 has a length (moving direction) of 1.25 mm, a thickness (floating direction) of 0.5 mm, a width (depth) of 1 mm, and an angle of the deflection surface 14a of 50 °. The apex angle of the V groove 14b is 80 °, and the depression angle 10 ° toward the deflecting surface 14a. The thickness of the open end of the V-groove 14b is 0.16 mm, the thickness of the closed end is 0.32 mm, and the cross-sectional area on the closed side is larger than the open side of the V'-groove 14b. The optical element 14 was molded using the injection mold shown in FIG. 19 having the inverted space (cavity) of the optical element 14 shown in FIG. 8 and a resin-filling gate. The resin used was ZEONEX (registered trademark) 480R (Nippon Zeon Co., Ltd., refractive index 1.525) which is a thermoplastic resin.

 [0094] In the V groove 14b of the optical element 14, three of the optical fiber 11, the GRIN lens 12 and the GRIN lens 13 are joined together by a melting process, and the end surface of the GRIN lens 13 is made to be the end of the V groove 14b of the optical element 14. It is pressed against the closed end face and fixed so that no air layer is caught between the faces.

 [0095] The luminous flux emitted from an optical fiber 11 with a diameter of 85 mm is a GRIN lens with a length of 0.595 mm.

 12 becomes a parallel light beam, passes through the GRIN lens 13 having a length of 0 · 085 mm, and enters the optical element 14 with the deflecting surface 14a at 50 °, with the parallel light as convergent light.

Accordingly, the angle of incidence on the deflecting surface 14a is 50 °. The light beam deflected to about 100 ° by the deflecting surface 14a is condensed almost perpendicularly to the incident end surface of the optical waveguide 16 to form a good light spot and optically coupled. By setting the angle at which the light beam is deflected by the deflecting surface to 100 °, the reflecting state on the deflecting surface 14a of the ZEONEX (registered trademark) 480R optical element with a small refractive index can be made closer to total reflection. Yes, and V?効率 By tilting 14b by 10 °, light is incident in a direction perpendicular to the incident surface of the optical waveguide 16, so that the light efficiency is good. Light The mode field diameter of the bar 11 is about 10 m, and the mode field diameter of the optical waveguide 16 is also about 10 mm. By combining the GRIN lens 12 and the GRIN lens 13, a light spot that can correspond to the mode field diameter of the optical waveguide 16 can be formed by the light emitted from the optical fiber 11, and the magnification of this optical system is 1: 1. It is possible to do S.

 Table 2 shows numerical values relating to the GRIN lenses 12 (GRIN lens A) and 13 (GRIN lens B) and the optical element 14.

 [0098] [Table 2]

[0099] (Example 2)

 In FIG. 6, 60 is an optical head, 11 is an optical fiber, 12 is a GRIN lens (GRIN lens A), 13 is a GRIN lens (GRIN lens B), and 64 is V?冓 An optical element in which 64b and the deflecting surface 64a are integrated, 15 is a slider, and 16 is an optical waveguide. FIG. 7 is a perspective view of the optical element 64. The optical element 64 is made by injecting molten resin (described later) into a mold (described later) having an inverted shape of the optical element 64 from a gate provided on a mold surface that forms a surface that is not a deflection surface. After the step of forming and the step of injection molding, after passing through the process of releasing the optical element molded from the mold, it was obtained by removing the gate trace.

 [0100] FIG. 11 is a perspective view showing a space (cavity) filled with resin and a gate filled with resin in a state where the mold for molding optical element 64 is closed.

 [0101] As shown in Fig. 11, the gate 64g, which is a resin injection port in a mold for molding the optical element 64 by resin molding by an injection molding method, has a deflection surface 64a and a V 'groove 64b opened! /, Surface 64d, surface 64e opposite to surface 64d where V-groove 64b is open, and surface 64c that is neither surface 64e where V-groove 64b is open Surface 64f— Prepare for one.

In FIG. 6, an optical element 64 is bonded and fixed on the same slider 15 as in the first embodiment. The optical element 64 has a length (moving direction) of 1.25 mm, a thickness (floating direction) of 0.5 mm (low step thickness of 0.34). mm), width (depth) lmm, and angle of deflection surface 64a is 45 °. The V ′ groove 64b is approximately parallel to the lower surface of the optical element 64 with an apex angle of 80 °. V-groove 64b has a thickness of 0.16mm at the open end, and the closed end has a thickness of 0.32mm (length 0.35mm, width (depth) lm m). The cross-sectional area of the closed side is made larger than the open side. The optical element 64 was molded using an injection mold having an inverted space (cavity) of the optical element 64 shown in FIG. 11 and a resin filling gate. The resin used is ZEONEX (registered trademark) 480R (Nippon Zeon Co., Ltd., refractive index 1.525) which is a thermoplastic resin.

[0103] V of optical element 64? The optical fiber 11, the GRIN lens 12, and the GRIN lens 13 are joined to the 64 b by a melting process, and the end face of the GRIN lens 13 is pressed against the closed end face of the V ′ groove 64 b of the optical element 64. Adhesion is fixed so that there is no air layer between the surfaces.

 [0104] The luminous flux emitted from an optical fiber 11 with a diameter of 85 mm is a GRIN lens with a length of 0.595 mm.

 12 becomes a parallel light beam, passes through a GRIN lens 13 having a length of 0 · 085 mm, enters parallel light as convergent light, and enters an optical element 64 having a deflection surface of 45 °.

 Accordingly, the incident angle to the deflecting surface 64a is 45 °. The light beam deflected to approximately 90 ° by the deflecting surface 64a is condensed almost perpendicularly to the incident end surface of the optical waveguide 16 to form a good light spot and optically coupled. The mode field diameter of the optical fiber 11 is about 10 m, and the mode field diameter of the optical waveguide 16 is also about 10 m. By combining the GRIN lens 12 and the GRIN lens 13, a light spot that can correspond to the mode field diameter of the optical waveguide 16 can be formed from the light emitted from the optical fiber 11, and the magnification of this optical system is 1: It can be set to 1 s.

 The numerical values for the GRIN lenses 12 (GRIN lens A) and 13 (GRIN lens B) and the optical element 64 are the same as those in Table 2.

[Example 3]

 From Example 2, the diameters of the optical fiber 11, the GRIN lens 12 and the GRIN lens 13 were changed to 85 μm force and 125 nm.

[0108] In FIG.冓 Three optical fibers 11 with a diameter of 125 m, GRIN lens 12 and GRIN lens 13 are joined together by melting to be integrated into 64b. Then, the end surface of the GRIN lens 13 is pressed against the closed end surface of the V-groove 64b of the optical element 64 and bonded and fixed so that no air layer is sandwiched between the surfaces.

 [0109] Since the diameter of the GRIN lens 12 and the GRIN lens 13 is increased from 85 m to 125 m, the position of the light emitted from the GRIN lens 13 is slightly shifted to the slider 15 side, and the condensing position is thereby shifted. The second embodiment is the same as the second embodiment except that the positions of the optical element 64, the slider 15, and the adhesive fixing are slightly shifted from the positions of the second embodiment.

 [0110] (Example 4)

 Example 2 is the same as Example 2 except that the size of the optical element 64 is as follows.

 In FIG. 6, the optical element 64 is bonded and fixed onto the slider 15. The optical element 64 has a length (moving direction) of 0.9 mm, a thickness (floating direction) of 0.5 mm (low step thickness of 0.34 mm), a width (depth) of 0.8 mm, and a deflection surface 64a angle of 45. °. The V groove 64b has an apex angle of 80 ° and is substantially parallel to the lower surface of the optical element 64. The thickness of the open end of V groove 64b is 0.16mm, and the thickness of the closed end is 0.332mm (length 0.35mm, width (depth) lmm) by increasing the thickness of the step V?冓 64b is open! /, Close from the side! /, Increase the cross-sectional area! The optical element 64 was molded using an injection mold having an inverted shape space (cavity) of the optical element 64 shown in FIG. 11 and a resin filling gate.

 [0112] The difference in size between the slider 15 and the optical element 64 is 0.05 mm in length and 0.1 mm in width, but the effect of burrs generated during molding on the surface of the optical element 64 on which the slider 15 is fixed is also affected. It can be adhered and fixed well.

 [0113] (Example 5)

 In FIG. 2, 3 is an optical head, 11 is an optical fiber, 12 is a GRIN lens (GRIN lens A), 13 is a GRIN lens (GRIN lens B), 14 is inclined by 2 °, and a V-groove 14b and a deflection surface 14a. And 15 is a slider, and 16 is an optical waveguide. A perspective view of the optical element 14 is shown in FIG. The optical element 14 is injected by injecting molten resin (described later) into a mold having a reversed shape of the optical element 14 (described later) from a gate provided on a mold surface that forms a surface that is not a deflection surface. After the step of molding and the step of injection molding, after passing through the step of releasing the optical element molded from the mold, it was obtained by removing the gate trace.

In FIG. 2, the optical element 14 having the V groove 14b provided on the slider 15 is bonded and fixed. The The optical element 14 has a length (moving direction) of 0.85 mm, a thickness (flying direction) of 0.2 mm, a width (depth) of 0.7 mm, and an angle of 46 ° of the deflecting surface 14a. The apex angle of the V groove 14b is 88 °, and the depression angle 2 ° toward the deflecting surface 14a. The thickness at the open end of the V-groove 14b is 0.1 mm, the thickness at the closed end is 0.12 mm, and the cross-sectional area on the closed side is larger than the open side of the V'-groove 14b. The optical element 14 was molded using the injection mold shown in FIG. 19 having the inverted space (cavity) of the optical element 14 shown in FIG. 8 and a resin-filling gate. The resin used was ZEONEX (registered trademark) 480R (Nippon Zeon Co., Ltd., refractive index 1.525) which is a thermoplastic resin.

[0115] V of optical element 14? The optical fiber 11, the GRIN lens 12, and the GRIN lens 13 are joined to each other by a melting process, and the end face of the GRIN lens 13 is pressed against the closed end face of the V groove 14 b of the optical element 14. Adhesion is fixed so that there is no air layer between the surfaces.

 [0116] The luminous flux emitted from an optical fiber 11 with a diameter of 80 mm is a GRIN lens with a length of 0.595 mm.

 12 becomes a parallel light beam, passes through a GRIN lens 13 having a length of 0 · 085 mm, and enters parallel light as convergent light to an optical element 14 having a deflection surface 14a of 46 °.

 [0117] Accordingly, the incident angle on the deflecting surface 14a is 46 °. The light beam deflected to approximately 92 ° by the deflecting surface 14a is condensed almost perpendicularly to the incident end surface of the optical waveguide 16 to form a good light spot and optically coupled. The mode field diameter of the optical fiber 11 is about 10 m, and the mode field diameter of the optical waveguide 16 is also about 10 m. By combining the GRIN lens 12 and the GRIN lens 13, a light spot that can correspond to the mode field diameter of the optical waveguide 16 can be formed from the light emitted from the optical fiber 11, and the magnification of this optical system is 1: It can be set to 1 s.

 The numerical values for the GRIN lenses 12 (GRIN lens A) and 13 (GRIN lens B) and the optical element 14 are the same as in Table 2.

Claims

The scope of the claims  [1] In an optical element mounted on a slider that moves over a recording medium,  A groove that is formed by injection molding using a mold having a reversal shape of the optical element using a resin that transmits light guided from a light source as a material, and one end is opened and the other end is closed. Forming using the mold having a deflection surface for deflecting the light incident from the other end, and having a gate into which the resin is injected into a surface of the mold that forms a surface that is not the deflection surface An optical element.  [2] In addition to the deflection surface, the groove is open! /, A surface of the mold, and the groove is open! /, A surface of the mold that is not the surface opposite to the surface of the mold. 2. The optical element according to claim 1, wherein the optical element is molded using the mold having a gate into which the resin is injected.  [3] In addition to the deflection surface, the surface where the groove is open! /, And the surface opposite to the surface where the groove is open! /, The surface where the groove is open 3. The optical element according to claim 2, wherein the optical element is formed using the mold including a gate into which the resin is injected on a surface of the mold that forms a non-exposed surface. [4] According to any one of claims 1 to 3, wherein the thickness of the resin forming the bottom of the groove is less on the other end side than on the one end side. The optical element described. 5. The optical element according to any one of claims 1 to 4, wherein the depth of the groove is shallower on the other end side than on the one end side. [6] According to any one of claims 1 to 5, wherein the thickness of the optical element is not less than 0.1 mm and not more than lmm and satisfies the following conditional expression: The optical element described.  b <L ≤ k X b  c <W ≤ k X c  However,  k = 2: coefficient  b: Length of the slider on which the optical element is placed in the same direction as the slider moves c: Width of the slider on which the optical element is placed in the direction perpendicular to the direction in which the slider moves L: Length of optical element in the same direction as b  W: Width of optical element in the same direction as c [7] The groove according to any one of claims 1 to 6, wherein a condensing element for condensing light guided from the light source is fixed to the groove. Optical element. 8. The optical element according to claim 7, wherein the light condensing element is fixed to a bottom of the groove.  [9] The range of claim 7 or 8, wherein the condensing element is a gradient index lens coupled to a linear light guide that guides light from the light source. Optical elements.  [10] An optical head comprising: the optical element according to any one of claims 7 to 9; and the slider that holds the optical element.  [11] The slider is fixed to a surface having the groove opening of the optical element, and a suspension for supporting the optical element is fixed to a surface opposite to the surface having the groove opening. The optical head according to claim 10.  [12] In a method of manufacturing an optical element mounted on a slider that moves on a recording medium! /, A material that is guided from a light source and that transmits light is used. A surface that is not the deflection surface is formed in a mold having a reversing shape of the optical element having a closed groove and a deflection surface that deflects the light incident from the other end of the groove. A step of injecting the resin from a gate provided on the surface of the mold and injection molding; and a step of releasing the optical element molded from the mold after the injection molding step. A method for manufacturing an optical element.  [13] In addition to the deflection surface, the gate may be any one of a surface on which the groove is open and a surface on the opposite side of the surface on which the groove is open and V. 13. The method of manufacturing an optical element according to claim 12, wherein the optical element is provided on a surface of a mold.  [14] In addition to the deflection surface, the surface on which the groove is open, and the surface opposite to the surface on which the groove is open, the gate has any of the surfaces on which the groove is open! / 14. The method for manufacturing an optical element according to claim 13, wherein the optical element is provided on the surface of the mold forming the surface. [15] The thickness of the resin forming the bottom of the groove is less at the other end than at the one end. 15. The method of manufacturing an optical element according to any one of claims 12 to 14, characterized by:  16. The method for manufacturing an optical element according to any one of claims 12 to 15, wherein the depth of the groove is shallower on the other end side than on the one end side. [17] The method according to any one of claims 12 to 16, wherein the thickness of the optical element is not less than 0.1 mm and not more than lmm and satisfies the following conditional expression: The manufacturing method of the optical element of description.  b <L ≤ kXb  c <W ≤ kXc  However,  k = 2: coefficient  b: Length of the slider on which the optical element is placed in the same direction as the slider moves  c: Width of the slider on which the optical element is placed in the direction perpendicular to the direction in which the slider moves  Length of optical element in the same direction as L: b  W: Width of optical element in the same direction as c