JP4498429B2 - Near-field optical head - Google Patents

Description

  The present invention relates to a near-field optical head. More specifically, the near-field optical head has been devised so that the resolution can be increased and the mechanical strength can be increased, and the evanescent field scattering efficiency can be increased easily. The present invention relates to a field optical head.

Currently, read-only information reproducing devices represented by CDs and CD-ROMs are widely used. In these information reproducing devices, information recorded on the optical disk is reproduced using light. For example, in a CD, pits having a size of about the wavelength of a laser beam used for reproduction and a depth of about a quarter of the wavelength are recorded on the surface as uneven information. The optical interference phenomenon is used to reproduce the image. When the spot of the laser beam is irradiated onto the pit, the depth of the pit is a quarter wavelength, so that the reflected light reflected on the bottom surface of the pit and the reflected light reflected on the surface outside the pit The optical path difference is a half wavelength of the irradiated laser light. For this reason, the reflected light obtained compared with the case where the spot of a laser beam is irradiated on the surface outside a pit becomes weak. In this way, the presence or absence of pits is determined by detecting the intensity of reflected light, and reproduction of information recorded on the optical disk is achieved.

  A lens optical system used in a conventional optical microscope is used for the laser light irradiation system and the detection system described above. However, the spot size of the laser beam cannot be reduced to a half wavelength or less because of the diffraction limit of light. On the other hand, in order to increase the information recording density of the optical disc, the pit size must be reduced and the track pitch must be reduced. For this reason, if the information recording unit has a size smaller than the wavelength of the laser beam, the conventional information reproducing apparatus cannot cope.

  In view of such problems, an optical memory using a near-field optical microscope technique has been proposed in recent years. The near-field optical microscope uses, for example, a probe having a microscopic aperture having a diameter equal to or smaller than the wavelength of laser light to be irradiated, for example, about 1/10 of the wavelength. The non-propagating component (evanescent field) of the light existing in the light is observed to observe the minute surface structure and optical characteristic distribution of the sample. In such a near-field optical microscope, the near-field light is generated by irradiating propagation light from the back of the sample to generate near-field light on the sample surface and bringing the probe micro-aperture and the sample surface close to the diameter of the probe micro-opening. Is scattered as a propagating light from the minute aperture. Near-field light generated on the sample surface is accompanied by intensity and phase reflecting the fine structure and optical property distribution of the sample surface. By processing this extracted propagation light with a photodetector, a conventional optical microscope is used. Enables observations with resolutions that could not be achieved.

  In the field of the near-field optical microscope, a method using an AFM cantilever whose tip has been sharpened is often used. Literature "Hulst et al., Appl. Phys. Lett. (1993) Vol. 62, p461", literature "Hulst et al., SPIE (1992) Vol. 1639, p36", JP-A-6-160719, and PCT International Application Publication No. WO95 / 03561 describes a technique for forming a light-transmitting tip at the tip of an AFM cantilever. In addition, the literature “Zenhausern et al., Appl. Phys. Lett. (1994) Vol. 65, p1623”, the literature “Bachelot et al., Ultramicroscopy (1995) Vol. 61, p111”, and the near-field optics research group. In the preliminary report (Preparation for the 4th Research Discussion Meeting of Near Field Optics Research Group "Reflective near-field optical microscope using a metal probe and observation of a semiconductor sample having a fine structure" 1995, p53), a chip that does not transmit light is used for AFM. Techniques for forming cantilevers are described.

  By applying the near-field optical technology as described above to an optical memory, information can be detected from an optical disk configured with information recording units equal to or less than the wavelength of the laser beam.

  However, in the above method for forming a microscopic aperture, it is difficult to form a microscopic aperture, and since there is a limit to the size of the aperture, it is difficult to improve the resolution to several tens of nm or less. there were. On the other hand, the method using the AFM cantilever has a problem that since the tip is sharpened, the mechanical strength is weak and the reliability is low for use as a head. For example, the chip is easily damaged by dust on the media surface or vibration of the media. In addition, a lot of sharpening processes are required to form a chip, and assuming that this chip is formed on a flying head, it is difficult to match the height of the flying head and the tip of the chip. There was a point. Furthermore, since the surface area of the chip is small, there is a problem that the scattering efficiency of the evanescent field is lowered.

  Therefore, the present invention has been made in view of the above, and provides a near-field optical head that can increase the resolution and mechanical strength, is easy to manufacture, and has high evanescent field scattering efficiency. Objective.

  In order to achieve the above-described object, the near-field optical head having the first feature of the present invention has a head end portion that is close to the medium at a distance equal to or smaller than the light wavelength and irradiates the medium with light. In the near-field optical head for reproducing the information recorded on the medium based on the scattered light intensity of the evanescent field generated at the head, the head tip is formed in an edge shape intersecting two planes.

  A near-field optical head having the second feature of the present invention is the near-field optical head, wherein one of the two surfaces is the bottom surface of the slider.

  A near-field optical head having the third feature of the present invention is the above-described near-field optical head, further comprising a light receiving element disposed above the head.

  The near-field optical head having the fourth feature of the present invention is the near-field optical head described above, wherein a light receiving element is provided in the vicinity of the head among the sliders having the head.

  The near-field optical head having the fifth feature of the present invention is the above-mentioned near-field optical head, wherein a waveguide is provided in the vicinity of the head of the slider having the head, and a light receiving element is provided in the waveguide. It is a thing.

  In the near-field optical head having the sixth feature of the present invention, in the near-field optical head, a metal film is further provided on all or part of the bottom surface of the slider, and the edge portion is formed by the metal film. Is.

  A near-field optical head having a seventh feature of the present invention is the near-field optical head described above, wherein the slider having the head is made of a light-transmitting material, and the light source is arranged on the slider side with respect to the medium. It is.

  The near-field optical head having the eighth feature of the present invention is the above-mentioned near-field optical head, wherein the slider having the head is made of a light-transmitting material, and a light source is provided on the slider.

  The near-field optical head having the ninth feature of the present invention is the above-mentioned near-field optical head, wherein a slider having the head is provided with a light source and a waveguide for transmitting light from the light source.

  As described above, according to the near-field optical head having the first feature of the present invention, the head tip has an edge shape intersecting two planes, so that the mechanical strength of the head is improved and the head Increased reliability.

  Further, according to the near-field optical head having the second feature of the present invention, since one of the two surfaces forming the edge is the bottom surface of the slider, the chip and the slider as in the case where the chip is formed on the slider are used. No height adjustment is required. In addition, the sharpening process is not required, and the edge portion can be formed by etching, so that manufacturing is easy.

  Further, according to the near-field optical head having the third feature of the present invention, since the light receiving element is arranged above the head, the head becomes compact.

  According to the near-field optical head having the fourth feature of the present invention, since the light receiving element is provided in the vicinity of the head among the sliders having the head, the head becomes compact, and the light receiving efficiency of scattered light is improved. improves.

  According to the near-field optical head having the fifth feature of the present invention, a waveguide is provided in the vicinity of the head of the slider having the head, and the light receiving element is provided in the waveguide. Since only the scattered light can be selectively guided to the light receiving element, the S / N ratio is improved.

  According to the near-field optical head having the sixth feature of the present invention, a metal film is provided on all or part of the bottom surface of the slider, and the edge portion is formed of the metal film. Since light can be reflected at the bottom of the slider, stray light can be reduced. In addition, since the edge is formed of the metal film, the scattering efficiency is improved.

  Further, according to the near-field optical head having the seventh feature of the present invention, the slider having the head is made of a light-transmitting material, and the light source is arranged on the slider side with respect to the medium. Become.

  According to the near-field optical head having the eighth feature of the present invention, the slider having the head is made of a light-transmitting material, and the light source is provided on the slider. Also suitable for mass production.

  According to the near-field optical head having the ninth feature of the present invention, the slider having the head is provided with the light source and the waveguide for transmitting the light of the light source, so that stray light entering the light receiving element can be reduced. Therefore, the S / N ratio is improved.

Hereinafter, the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.
(Embodiment 1)
1 is a schematic perspective view showing a near-field optical head according to Embodiment 1 of the present invention. FIG. 2 is an enlarged side view showing the tip of the head shown in FIG. The near-field optical head 100 includes a convex head 2 positioned opposite to the disk 1 and a light receiving element 3 disposed above the head tip. The head 2 has a beam portion 21, and the tip portion 22 has an edge shape. The edge portion 23 of the distal end portion 22 is constituted by a side 26 where the bottom surface 24 and the side surface 25 of the head 2 intersect. The bottom surface 24 and the side surface 25 intersect substantially perpendicularly. When the edge portion 23 is viewed microscopically (nm level), the edge portion 23 has a curved surface. The curvature radius Rt corresponds to the reproducible bit size, and the smaller the curvature radius Rt (the sharper), the higher the density recording can be performed. The edge portion 23 can be formed at an angle determined by the crystal plane if it is formed by using anisotropic etching of Si. Further, even with materials other than Si, considerable sharpness can be realized by accurately setting the etching conditions (no matter of wet etching and dry etching).

  Moreover, the edge part 23 is formed when two planes cross | intersect and an intersection angle is not ask | required. For example, the edge portion may be formed by intersecting two planes at an angle of 30 degrees or 60 degrees. Assuming that the cross-section is a plane in which sides formed by two planes intersect vertically, the edge portion 23 has the same curvature radius Rt regardless of the cross-section. On the other hand, if a plane including a side formed by the two planes is taken as a cross section, the curvature becomes zero. On the other hand, in the above-described conventional chip, the apex of any of a needle shape, a cone shape, and a pyramid shape is hemispherical when viewed microscopically. For this reason, if the plane including the apex and the sphere center is a cross section, any cross section has a curvature.

  The radius of curvature Rt of the edge portion 23 must be about the shortest bit length formed on the disk 1 or smaller. When the curvature radius Rt of the edge portion 23 is larger than the bit length, the presence / absence of the bit 11 cannot be read with good S / N. For example, if the bit length is 100 nm, the radius of curvature Rt of the edge portion 23 must be about 100 nm or less.

  Next, the width W1 of the edge portion 23 may be larger than the bit width on the disk 1, but it does not have to be on the adjacent track 12. In addition, the convex wide portion 27 (width W2) may be applied to the adjacent track 12, but in this case, the length L of the beam portion 21 should be ensured to prevent crosstalk from the adjacent track 12. Good.

Moreover, as shown in FIG. 3, the edge part 23 itself may have a curvature (curvature radius Rn). In this case, the bottom surface 24 becomes a curved surface, and the bottom surface 24 and the side surface 25 intersect to form the edge portion 23. The edge portion 23 also has the same radius of curvature Rt as in FIG. 2 when viewed microscopically. Since the near-field optical head 100 cannot completely track the bit 11, the deviation in the track orthogonal direction is corrected by feedback control. Here, if the radius of curvature Rn in the track orthogonal direction is about the bit width, the signal (presence / absence of bits) by the feedback control in the track orthogonal direction becomes too large to cause noise, and the presence / absence of bits in the track direction is used as a signal. Cannot read. Therefore, for practical use, even if this noise is reduced by a filter from the feedback frequency, it is preferable to make it smaller by about two digits than the signal of the presence / absence of bits in the track direction. Also, in view of the current practical technical level (DVD and the like), the noise level needs to be 4 digits or more smaller than the signal level. From the above, it is appropriate that the radius of curvature Rn in the track orthogonal direction is infinite, but it is considered that there is no practical problem if it is increased by about 5 times or more, preferably 50 times or more the bit width.

  Returning to FIG. 2, the distance d between the edge portion 23 and the disk 1 is controlled to be equal to or less than the light wavelength. For controlling the distance d, a flying head of a so-called hard disk drive (HDD) is used, and the near-field optical head 100 is floated by air film lubrication. When the flying head technology is used, it is necessary to provide a tapered surface on the near-field optical head 100 to form a wedge-shaped channel. According to the head flying technique, the distance d can be controlled to about 50 nm. Further, as in the case of an AFM cantilever, distance detection may be performed and feedback control may be performed using a piezo element or the like. Further, it may be realized by a contact state in which a thin lubricating film (such as oil or water) of about several nm is interposed, or may be a complete contact state.

  When light 4 is irradiated from the light source (not shown) to the back surface of the disk 1 at an incident angle that satisfies the total reflection condition, an evanescent field 41 is generated on the disk surface. By inserting the edge portion 23 into this, scattered light 42 is generated. The light intensity of the scattered light 42 changes depending on the presence / absence of the bit 11. The generated scattered light 42 is received by the light receiving element 3. The light receiving element 3 performs photoelectric conversion according to the light intensity of the scattered light 42. Thereby, the information on the disc 1 can be reproduced.

  Further, the tip portion 22 of the head may have a sword shape as shown in FIG. 4 in addition to the strip shape as shown in FIG. Further, it may be circular as shown in FIG. As a recording state on the disk 1, bits may be recorded based on a difference in transmittance or reflectance, or may be recorded as unevenness. The near-field light includes far-field light.

As described above, according to the near-field optical head 100, the edge portion 23 is superior in mechanical strength as compared with a conventional tip subjected to sharpening processing, and thus the reliability of the head is increased. Next, the chip formation requires many sharpening processes, and it is difficult to manufacture the chip tip and the slider at the same height. On the other hand, the edge portion 23 can be relatively easily formed on a part of the head slider by an etching process, and the height adjustment with the bottom surface of the head slider is unnecessary. Furthermore, since the area where the edge portion 23 scatters the evanescent field 41 is larger than that of the chip, the intensity of the scattered light obtained is increased.
(Embodiment 2)
FIG. 6 is a schematic configuration diagram showing the structure of a near-field optical head according to Embodiment 2 of the present invention. This near-field optical head 200 is a more specific configuration of the near-field optical head 100 of the first embodiment. In the near-field optical head 200, the edge portion 202 (see FIG. 2) is formed on the bottom surface of the head slider 201. A tapered surface 203 is provided on the opposite side of the edge portion 202. The tapered surface 203 and the disk 204 form a wedge-shaped channel. The edge portion 202 is formed by an etching process. The near-field optical head 200 is supported by a suspension arm (not shown) and is driven by a voice coil motor (not shown). In addition, a lens 205 that collects scattered light and a light receiving element 206 are disposed obliquely above the head slider 201.

  When light 207 is irradiated from a light source (not shown) to the back surface of the disk 204 at an incident angle that satisfies the total reflection condition, an evanescent field 208 is generated on the disk surface. Since the head slider 201 floats obliquely, the edge portion 202 approaches the disk surface and scatters light. The light intensity of the scattered light 209 changes depending on the presence or absence of the bit 210. The generated scattered light 209 is collected by the lens 205. A light receiving element 206 is disposed at the condensing destination, and the scattered light 209 is received by the light receiving element 206. The light receiving element 206 performs photoelectric conversion according to the light intensity of the scattered light 209. As a result, information on the disc 204 is reproduced.

According to the near-field optical head 200, the distance between the edge portion 202 and the disk 204 can be easily controlled by performing the head floating technique. Further, since it is only necessary to form the edge portion 202 on the head slider 201, the head slider 201 is more compact than a general magnetic head and the cost is reduced.
(Embodiment 3)
FIG. 7 is a schematic configuration diagram showing the structure of a near-field optical head according to Embodiment 3 of the present invention. This near-field optical head 300 is a more specific configuration of the near-field optical head 100 of the first embodiment. In the near-field optical head 300, the edge portion 302 (see FIG. 2) is formed on the bottom surface of the head slider 301. A step portion 303 is formed in the vicinity of the edge portion 302 in the head slider 301. The step portion 303 is provided with a light receiving element 304. A tapered surface 305 is provided on the opposite side of the edge portion 302. The tapered surface 305 and the disk 306 form a wedge-shaped channel. The edge portion 302 is formed by an etching process. The near-field optical head 300 is supported by a suspension arm (not shown) and is driven by a voice coil motor (not shown).

  When light 307 is irradiated from a light source (not shown) to the back surface of the disk 306 at an incident angle that satisfies the total reflection condition, an evanescent field 308 is generated on the disk surface. Since the head slider 301 floats obliquely, the edge portion 302 approaches the disk surface and scatters light. The light intensity of the scattered light 309 changes depending on the presence or absence of the bit 310. The generated scattered light 309 is received by a light receiving element 304 provided in the vicinity of the edge portion 302 in the head slider 301. The light receiving element 304 performs photoelectric conversion according to the light intensity of the scattered light 309. As a result, information on the disk 306 is reproduced.

According to the near-field optical head 300, since the light receiving element 304 is directly provided on the head slider 301, the head becomes compact. In addition, the light receiving efficiency is improved by providing the light receiving element 304 in the vicinity of the edge portion 302.
(Embodiment 4)
FIG. 8 is a schematic configuration diagram showing the structure of a near-field optical head according to Embodiment 4 of the present invention. This near-field optical head 400 is a more specific configuration of the near-field optical head 100 of the first embodiment. In the near-field optical head 400, the edge portion 402 (see FIG. 2) is formed on the bottom surface of the head slider 401. Further, a step portion 403 is formed in the vicinity of the edge portion 402 in the head slider 401. The step 403 is provided with a light receiving element 404. A metal film 405 is formed on the bottom surface of the head slider 401. The edge portion 402 is formed by this metal film 405. This is because the metal edge has higher scattering efficiency than the dielectric edge. Further, the metal film may be formed only on the edge portion 402 instead of the entire bottom surface of the head slider 401. A tapered surface 406 is provided on the opposite side of the edge portion 402. The tapered surface 406 and the disk 407 form a wedge-shaped channel. The edge portion 402 is formed by an etching process. The near-field optical head 400 is supported by a suspension arm (not shown) and is driven by a voice coil motor (not shown).

  In the portion where the head slider 401 does not exist, the light 408 is incident on the disk 407 under the total reflection condition, and thus is totally reflected. In a portion where the head slider 401 is present at a distance equal to or smaller than the wavelength from the disk 407 (other than the edge portion), the distance between the head slider 401 and the disk 407 is not equal, so the light 408 passes through the disk surface. The transmitted light (not shown) is reflected by the metal film 406 on the bottom surface of the head slider 401. Alternatively, in the case where the metal film 406 is partially formed, light is reflected at a portion where the metal film 406 is provided. Thus, stray light entering the light receiving element 404 is reduced by forming the metal film 405 on the bottom surface of the head slider 401 and reflecting the light. An absorption film may be formed instead of the reflection film. However, it is not preferable to form the edge portion 402 with an absorption film.

The information reproduction principle is the same as in the third embodiment. That is, the edge portion 402 of the flying head slider 401 enters the evanescent field 409 on the disk surface to scatter light. The light intensity of the scattered light 410 changes depending on the presence or absence of the bit 411. The generated scattered light 410 is received by a light receiving element 404 provided in the vicinity of the edge portion 402 of the head slider 401. The light receiving element 404 performs photoelectric conversion according to the light intensity of the scattered light 410. As a result, information on the disk 407 is reproduced.
(Embodiment 5)
FIG. 9 is a schematic configuration diagram showing the structure of a near-field optical head according to Embodiment 5 of the present invention. The near-field optical head 500 has substantially the same configuration as the near-field optical head 400 of the fourth embodiment, except that a waveguide is formed in the light receiving element. In the near-field optical head 500, the edge portion 502 (see FIG. 2) is formed on the bottom surface of the head slider 501. Further, a step portion 503 is formed in the vicinity of the edge portion 502 in the head slider 501. The step portion 503 is provided with a light receiving element 504 and a waveguide 505. A metal film 506 is formed on the bottom surface of the head slider 501. The edge portion 502 is formed by this metal film 506. This is because the metal edge has higher scattering efficiency than the dielectric edge. Further, the metal film 506 may be formed only on the edge portion 502 instead of the entire bottom surface of the head slider 501. A tapered surface 507 is provided on the opposite side of the edge portion 502. The tapered surface 507 and the disk 508 form a wedge-shaped channel. The edge portion 502 is formed by an etching process. The near-field optical head 500 is supported by a suspension arm (not shown) and is driven by a voice coil motor (not shown).

  When light 509 is irradiated from a light source (not shown) to the back surface of the disk 508 at an incident angle that satisfies the total reflection condition, an evanescent field 510 is generated on the disk surface. Since the head slider 501 floats obliquely, the edge portion 502 approaches the disk surface and scatters light. The light intensity of the scattered light 511 varies depending on the presence / absence of the bit 512. The generated scattered light 511 passes through the waveguide 505 provided in the vicinity of the edge portion 502 in the head slider 501 and is received by the light receiving element 504. The light receiving element 504 performs photoelectric conversion according to the light intensity of the scattered light 511. As a result, information on the disk 508 is reproduced.

According to the near-field optical head 500, since the waveguide 505 is formed on the light receiving element 504, the scattered light 511 from the edge portion 502 can be selectively guided to the light receiving element 504. For this reason, since the scattered light from the other does not enter into the light receiving element 504, the S / N ratio is improved. A lens may be provided at the tip of the waveguide 505. Further, since the light receiving element 504 is directly provided on the head slider 501, the head becomes compact. Further, by providing the light receiving element 504 in the vicinity of the edge portion 502, the light receiving efficiency is improved. Further, the light transmitted through the disk surface is reflected by the metal film 506 formed on the bottom surface of the head slider 501. For this reason, stray light entering the waveguide 505 is reduced. In addition, scattered light due to small scratches or irregularities other than the bits on the disk 508, light transmitted through the head slider 501 and the like become stray light. Hateful.
(Embodiment 6)
FIG. 10 is a schematic configuration diagram showing the structure of a near-field optical head according to Embodiment 6 of the present invention. This near-field optical head 600 is not a system that totally reflects light on the disk surface, but a system that irradiates light from above the head slider. In the near-field optical head 600, the head slider 601 is made of a light transmissive material, and the edge portion 602 (see FIG. 2) is formed on the bottom surface of the head slider 601. A step portion 603 is formed in the vicinity of the edge portion 602 in the head slider 601. The step portion 603 is provided with a light receiving element 604 and a waveguide 605. A light source 606 and a lens 607 are disposed obliquely above the head slider 601. A tapered surface 608 is provided on the opposite side of the edge portion 602. The tapered surface 608 and the disk 609 form a wedge-shaped channel. The edge portion 602 is formed by an etching process. The near-field optical head 600 is supported by a suspension arm (not shown) and is driven by a voice coil motor (not shown).

Light 610 from the light source 606 is collected by the lens 607 and passes through the head slider 601 to illuminate the edge portion 602. As a result, an evanescent field 611 is generated on the surface of the edge portion 602. Since the head slider 601 floats obliquely, the edge portion 602 approaches the disk surface and scatters light. The light intensity of the scattered light 612 varies depending on the presence / absence of the bit 613. The generated scattered light 612 is received by the light receiving element 604 through the waveguide 605 provided in the vicinity of the edge portion 602 in the head slider 601. The light receiving element 604 performs photoelectric conversion according to the light intensity of the scattered light 612. As a result, information on the disk 609 is reproduced. According to the near-field optical head 600, since the light source 606 is disposed on the same side as the head, the apparatus can be made compact.
(Embodiment 7)
FIG. 11 is a schematic configuration diagram showing the structure of a near-field optical head according to Embodiment 7 of the present invention. In the near-field optical head 700, the head slider 701 is made of a light transmissive material, and the edge portion 702 (see FIG. 2) is formed on the bottom surface of the head slider 701. A light receiving element 703 and a waveguide 704 are provided in the vicinity of the edge portion 702 of the head slider 701. Further, a light source 705 and a lens 706 are incorporated in the head slider 701. A tapered surface 707 is provided on the opposite side of the edge portion 702. The tapered surface 707 and the disk 708 form a wedge-shaped channel. The edge portion 702 is formed by an etching process. The near-field optical head 700 is supported by a suspension arm (not shown), and is a voice coil motor (not shown).
Driven by.

Light 709 from the light source 705 is collected by the lens 706 and passes through the head slider 701 to illuminate the edge portion 702. As a result, an evanescent field 710 is generated on the surface of the edge portion 702. Since the head slider 701 floats obliquely, the edge portion 702 approaches the disk surface and scatters light. The light intensity of the scattered light 711 varies depending on the presence / absence of the bit 712. The generated scattered light 711 passes through the waveguide 704 provided in the vicinity of the edge portion 702 of the head slider 701 and is received by the light receiving element 703. The light receiving element 703 performs photoelectric conversion according to the light intensity of the scattered light 711. As a result, information on the disc 708 is reproduced. According to the near-field optical head 700, since the light source 705 and the lens 706 are incorporated in the head slider 701, the size becomes compact. Also suitable for mass production.
(Embodiment 8)
FIG. 12 is a schematic configuration diagram showing the structure of a near-field optical head according to Embodiment 8 of the present invention. In the near-field optical head 800, the edge portion 802 (see FIG. 2) is formed on the bottom surface of the head slider 801. A light receiving element 803 and a waveguide 804 are provided in the vicinity of the edge portion 802 of the head slider 801. Further, a light source 805 and a waveguide 806 are incorporated in the head slider 801. A tapered surface 807 is provided on the opposite side of the edge portion 802. The tapered surface 807 and the disk 808 form a wedge-shaped channel. The edge portion 802 is formed by an etching process. The near-field optical head 800 is supported by a suspension arm (not shown) and is driven by a voice coil motor (not shown).

  Light 809 from the light source 805 passes through the waveguide 806 and illuminates the edge portion 802. As a result, an evanescent field 810 is generated on the surface of the edge portion 802. Since the head slider 801 floats obliquely, the edge portion 802 approaches the disk surface and scatters light. The light intensity of the scattered light 811 changes depending on the presence or absence of the bit 812. The generated scattered light 811 is received by the light receiving element 803 through the waveguide 804 provided in the vicinity of the edge portion 802 of the head slider 801. The light receiving element 803 performs photoelectric conversion according to the light intensity of the scattered light 811. As a result, information on the disk 808 is reproduced. According to the near-field optical head 800, only the edge portion 802 can be illuminated by the waveguide 806, so that stray light entering the light receiving element 803 can be reduced. Further, since the light source 805 is incorporated in the head slider 801, the size is reduced. Also suitable for mass production. A lens may be disposed at the tip of the waveguide 806.

  In the above-described embodiment, various means, members, or structures have been described in a limited manner, but can be appropriately modified within a range that can be designed by those skilled in the art.

1 is a schematic perspective view showing a near-field optical head according to Embodiment 1 of the present invention. FIG. 2 is an enlarged side view showing a head tip portion shown in FIG. 1. FIG. 2 is an enlarged front view showing a head tip portion shown in FIG. 1. It is a schematic perspective view which shows the modification of the near-field optical head shown in FIG. It is a schematic perspective view which shows the modification of the near-field optical head shown in FIG. It is a schematic block diagram which shows the structure of the near-field optical head which concerns on Embodiment 2 of this invention. It is a schematic block diagram which shows the structure of the near-field optical head which concerns on Embodiment 3 of this invention. It is a schematic block diagram which shows the structure of the near-field optical head based on Embodiment 4 of this invention. It is a schematic block diagram which shows the structure of the near-field optical head based on Embodiment 5 of this invention. It is a schematic block diagram which shows the structure of the near-field optical head based on Embodiment 6 of this invention. It is a schematic block diagram which shows the structure of the near-field optical head based on Embodiment 7 of this invention. It is a schematic block diagram which shows the structure of the near-field optical head based on Embodiment 8 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Near-field optical head 1 Disk 11 Bit 12 Track 2 Head 21 Beam part 22 Tip part 23 Edge part 24 Bottom face 25 Side face 26 Side 27 Wide part 3 Light receiving element 4 Light 41 Evanescent field 42 Scattered light

Claims (8)

Has a beam,
Based on the scattered light intensity of the evanescent field generated when the head tip formed at the tip of the beam part is brought close to the medium at a distance equal to or smaller than the light wavelength and the medium is irradiated with light. In a near-field optical head that reproduces recorded bit information,
In a longitudinal section that is perpendicular to the media and is along the track direction of the media of the beam portion,
A first surface facing the media;
A second surface that intersects the first surface and is provided at the tip of the head,
A near-field optical head, wherein a radius of curvature along the track direction of the medium of an edge shape at an intersection of the first surface and the second surface is equal to or less than the shortest bit length.   The near-field optical head according to claim 1, wherein a light receiving element is disposed above the head.   The near-field optical head according to claim 1, wherein a light receiving element is provided in the vicinity of the head of the slider having the head.   The near-field optical head according to claim 1, wherein a waveguide having a waveguide is provided in the vicinity of the head of the slider having the head, and a light receiving element is provided in the waveguide.   5. The near-field optical head according to claim 1, wherein a metal film is provided on all or part of the bottom surface of the slider, and the head tip is formed of the metal film.   6. The near-field optical head according to claim 1, wherein a slider having the head is made of a light-transmitting material, and a light source is disposed above the slider.   6. The near-field optical head according to claim 1, wherein a slider having the head is made of a light-transmitting material, and a light source is provided in addition to the slider bottom surface of the slider.   6. The near-field optical head according to claim 1, wherein a slider having the head is provided with a light source and a waveguide that transmits light from the light source to the tip of the head.

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