JPH11288537A - Magneto-optical head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magneto-optical head capable of reproducing a ultra high densely recorded fine magnetic domain with high resolution and high sensitivity. SOLUTION: A floating type magneto-optical head 100 is provided with a solid immersion lens 10 and a magnetic coil 4 on a slider 2. A magnetic domain magnify-reproduced film 61 is formed on the bottom surface of the lens 10. At the time of reproducing information, evanescent beams are exuded from the bottom surface of the lens to heat the fine area of the reproduced film 61 to deteriorate coercive force. The magnetic domain 55a of a recording layer is transferred to the heated fine area of the film 61 by leaked magnetic field from the magnetic domain 55a of a recording layer 55 existing under the head 100. A magnified magnetic domain is formed on the film 61 at the time of applying an external magnetic field of the same polarity as the magnetic domain of the recording layer by the coil 4. Thus, it is possible to distinguish the fine magnetic domain of the recording layer from another fine magnetic domain and to amplify the intensity of a reproduced signal to reproduced it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical head for recording or reproducing a magneto-optical recording medium at the time of recording or reproducing, and more particularly to recording on a high-density magneto-optical recording medium using a solid immersion lens. The present invention relates to a magneto-optical head for reproducing.

[0002]

2. Description of the Related Art In recent years, a magneto-optical recording medium capable of recording and reproducing a large amount of data corresponding to multimedia has been receiving attention. For example, recording on an overwritable magneto-optical recording medium is performed by irradiating the magneto-optical recording medium with laser light and applying a magnetic field corresponding to input information to the irradiation position of the laser light. At the time of reproduction of the magneto-optical recording medium, information is irradiated by irradiating the magneto-optical recording medium with laser light that is weaker than at the time of recording, and detecting the polarization angle of reflected light that depends on the recording magnetization direction of the return light of the laser light. Will be played. According to the recording / reproducing principle of such a magneto-optical recording medium, a recording / reproducing apparatus includes an optical element for condensing a laser beam in a spot shape on the magneto-optical recording medium and a magnetic element for applying a magnetic field to the magneto-optical recording medium. A coil is required. When a recording / reproducing apparatus is configured using these optical elements and magnetic coils, a magneto-optical head combining an optical element and a floating magnetic head is known in order to reduce the size of the apparatus.

As a magneto-optical head of such a magneto-optical recording / reproducing apparatus, for example, Japanese Patent Application Laid-Open No. Sho 58-118826 and Japanese Patent Publication No. Hei 3-38662 disclose a slider provided with a light-transmitting portion, A magneto-optical head in which a focusing lens is provided and a recording coil is provided in a slider portion which does not overlap the optical path is disclosed. JP-A-1-62850 discloses that
There is disclosed a magneto-optical head in which a specific slider is provided so as to face an objective lens, and a magnetic field applying coil is mounted on the slider. Also, JP-A-2-14440 discloses that
In order to control the position of the magneto-optical head, an objective lens position detecting circuit is provided, and the floating position of the slider on which the objective lens and the magnetic field generating coil are mounted is detected by the objective lens position detecting circuit, thereby driving the magneto-optical head. Discloses a magneto-optical disk drive for controlling an actuator for use. Further, Japanese Patent Application Laid-Open No. 3-241551 discloses that a magnetic head and an optical head disposed above the magnetic head are provided on both sides of a magneto-optical disk, and laser light is passed through the center of the coil to a recording medium. An irradiating magneto-optical recording device is disclosed.
The prior art aims to reduce the size of the device and perform highly accurate position control of the magneto-optical head. When recording information on a magneto-optical recording medium using the above-described magneto-optical head, it is desired to record information at a higher density.

[0004] Near-field optical recording using a solid immersion lens has attracted attention in order to enable higher density recording on a magneto-optical recording medium than before. The solid immersion lens cuts a part of a sphere made of a material having a refractive index higher than that of a vacuum, for example, glass having a high refractive index, so that the cut surface is parallel to the recording surface of the magneto-optical recording medium. These lenses are arranged, and the diffraction limit can be reduced by increasing the NA of the optical system. This is because the spot diameter at the time of recording can be made smaller than the minimum spot diameter in air by condensing the light incident on the lens in the solid immersion lens. By using a solid immersion lens to increase the NA of the optical system to greater than 1, and to obtain a spot diameter smaller than the minimum spot diameter in vacuum, BDTerris et al.
ical data storage using a solid immersion lens ”,
Applied Physics Letters, vol.65 pp.388-390 (1994)
In the report. As reported, the NA can be increased to n with respect to the refractive index n of the solid immersion lens, and can be increased to n ² times as large as the NA of the incident light. / N ² . If a blue laser is used, 125
The possibility of realizing a spot diameter of nm arises, in which case the recording density can be as high as about 40 gigabit square inches. B.
The report by D. Terris et al. Did not include a detailed description of the application of an external magnetic field, and that information was recorded using standard magneto-optical recording methods except when a solid immersion lens was used. Is described.

[0005]

As the density of a magneto-optical recording medium is increased, control of magnetic flux passing through a slider of a magneto-optical head becomes very important.
However, as recording density is increased with a magneto-optical head having a solid immersion lens mounted on a flying type slider, it becomes difficult to control the magnetic flux of an external magnetic field passing through the inside of the slider. For this reason, it is difficult to apply a stable external magnetic field to the spot portion of the laser beam irradiated on the magneto-optical recording medium, which hinders the increase in the density of the magneto-optical recording medium.

Further, when reproducing a magneto-optical recording medium, it is necessary to detect a tracking signal in order for the reproducing light to follow the track of the magneto-optical recording medium. This tracking signal is performed by detecting a guide groove or a servo pit using a reproduction light. However, if a hemispherical solid immersion lens is used to reproduce an ultra-high-density recording medium, a very small light is condensed at the center of the track, which causes a problem that a tracking signal is not detected.

Further, even if a minute magnetic domain or a minute mark can be detected using a solid immersion lens, there is a problem that the S / N is low because the intensity of a detection signal is extremely small.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an external recording device at a desired recording position when performing magneto-optical recording with a magneto-optical head using a solid immersion lens. An object of the present invention is to provide a magneto-optical head that can efficiently apply a magnetic field.

Another object of the present invention is to provide a magneto-optical head capable of detecting a guide groove or a servo pit using reproduction light and performing good tracking control even when a solid immersion lens is used. Is to provide.

Another object of the present invention is to provide a magneto-optical head capable of individually detecting minute recording marks with a sufficient reproduction signal intensity even when a solid immersion lens is used. is there.

[0011]

[Means for Solving the Problems]

According to a first aspect of the present invention, in a magneto-optical head for reproducing information from a magneto-optical recording medium having an information recording layer, the reproducing light is focused on the magneto-optical recording medium and irradiated. A magneto-optical head, comprising: a solid immersion lens for performing the above operation; and an information reproducing magnetic film fixed to a light exit surface of the solid immersion lens.

The magneto-optical head of the present invention includes a solid immersion lens as an optical element for converging and irradiating the magneto-optical recording medium with reproduction light. First, the principle of using a solid immersion lens to make the spot diameter of a laser beam applied to a recording medium smaller than the diffraction limit will be described with reference to FIG. Generally, the spot diameter S condensed through the optical element is represented by the following equation (1).

S = λ / (2NA) = λ / (2n · sin θmax) (1)

As shown in FIG. 6, the wavelength of the laser beam incident on the optical element 1 is λ, the numerical aperture of the optical element 1 is NA, the refractive index of the optical element 1 is n, and the outermost light beam of the incident light beam (FIG. (Solid line) and the optical axis (incident angle) is θmax.
When the wavelength λ of the laser beam is fixed, it can be seen from the above equation (1) that the spot diameter S can be reduced by increasing the NA. Since NA is defined by NA = n sin θmax, to obtain a large NA, the refractive index n and the angle θmax must be increased. Therefore, when a material having a high refractive index is used for the optical element 1, the wavelength of light incident on the inside of the optical element 1 is shortened. Further, when the incident light is refracted on the surface of the optical element 1 and collected on the bottom surface (light exit surface) 1a of the optical element 1, the incident angle θmax to the bottom surface in the optical element 1, that is, Incident angle θmax to the placed object
Can be made larger than the angle of incidence on the spherical surface of the optical element 1.

The optical element 1 is a hemispherical lens (solid immersion lens) formed by cutting a part of a sphere having a radius r. The cut surface of the optical element 1, that is, the exit surface 1a of the optical element 1 is cut perpendicular to the optical axis of the incident light. The cutting position of the optical element 1 is at r / n from the center of the sphere. When the magneto-optical head on which the optical element 1 is mounted is levitated, the exit surface 1a of the optical element 1 is made parallel to the surface 3a of the recording medium 3. As shown in FIG. 1, when the incident light is made to enter the optical element 1 such that the extension line (the broken line in the figure) of the incident light intersects at a position nr below the center of the optical element 1, the incident light becomes The light is condensed on the bottom surface 1a of the optical element. Here, when the recording medium 3 is arranged at a position within the attenuation distance 102 of the evanescent light from the bottom surface of the optical element, the optical element 1 forms a minute spot of light on the recording medium 3 via an evanescent field (gap of air). I do. The optical element 1 has a wavelength λ of the incident light in the optical element 1 as described above.
Θma due to shortening of the wavelength of light and refraction of the optical element 1 on the spherical surface
The NA can be increased up to n ² times by increasing x. In other words, the spot diameter of the laser beam can be reduced theoretically to 1 / n ² . Thereby, the optical element 1 makes the spot formed on the recording medium 3 smaller than the minimum spot obtained in vacuum.

In the present invention, a solid immersion lens according to the above principle is used for a magneto-optical head. The bottom surface of the solid immersion lens of the magneto-optical head according to the present invention, that is, the light emitting surface, is provided with an information reproducing magnetic layer onto which the magnetization information of the recording layer of the magneto-optical recording medium is transferred (see FIG. 1). At the time of reproducing information, evanescent light exudes from the bottom surface of the solid immersion lens to the information reproducing magnetic layer, and irradiates and heats an extremely narrow region of the information reproducing magnetic film. The temperature in this region rises and the coercive force of the magnetic film decreases,
Due to the leakage magnetic field from the magnetic domain of the information recording layer below this area, the magnetization information of the magnetic domain of the information recording layer is transferred to the reproducing magnetic film. The information on the information recording layer can be reproduced by reading out the transferred magnetization information of the magnetic domain with evanescent light. In the present invention, since a solid immersion lens is used, even if extremely minute magnetic domains are recorded in the information recording layer, the minute magnetic domains can be transferred to the reproducing magnetic film while being distinguished from other minute magnetic domains. This is extremely effective for reproducing a magneto-optical recording medium on which high-density recording has been performed.

It is preferable to apply the MAMMOS (Magnetic Amplified Magneto-Optical System) disclosed in WO98 / 02878 by the present applicant to the magneto-optical head of the present invention. That is, the information reproducing magnetic film can be a magnetic domain expansion reproducing film capable of expanding magnetic domains under an external field such as an external magnetic field and / or a reproduction light whose light intensity is modulated. MAMM
By applying OS reproduction, it is possible to independently extract the minute magnetic domains recorded in the information recording layer into the information reproducing layer, and expand the extracted (transferred) magnetic domains to amplify the reproduction signal intensity. Therefore, by using the magneto-optical head of the present invention, it is possible to reproduce a minute magnetic domain recorded at high density with high resolution and high sensitivity.

In the magneto-optical head of the present invention, a magnetic coil may be formed on the light exit surface of the solid immersion lens. By incorporating the magnetic coil into the solid immersion lens in this way, the magneto-optical recording / reproducing apparatus can be made compact, and a magnetic field can be applied to the magneto-optical recording medium with high efficiency during magneto-optical recording. .
Further, when performing MAMMOS reproduction, a magnetic field for magnetic domain expansion reproduction can be generated from a magnetic coil mounted on the light exit surface of the solid immersion lens.

According to a second aspect of the present invention, in a magneto-optical head for reproducing information from a magneto-optical recording medium having an information recording layer, a reproducing beam is focused on the magneto-optical recording medium and irradiated. A solid-state immersion lens is used to provide a magneto-optical head characterized in that the curved surface of the solid-state immersion lens includes its optical axis and has different radii of curvature r1 and r2 in lens cross sections orthogonal to each other.

It is known that when light is condensed using a hemispherical solid immersion lens, the light can be condensed within an extremely small range by its NA. However, usually, when reproducing a magneto-optical recording medium, it is necessary to detect a tracking signal in order to make the reproducing light follow a track of the magneto-optical recording medium. This tracking signal is performed by detecting a guide groove or a servo pit using a reproduction light. However, when a hemispherical solid immersion lens is used to reproduce an ultra-high-density recording medium, the light is condensed extremely small at the track center.
There is a disadvantage that the tracking signal is not detected. Therefore, in the magneto-optical head according to the second aspect of the present invention, the solid immersion lens is not a complete hemispherical type,
The curved surface of the lens has different radii of curvature r1 and r2 in the lens sections including the optical axis and orthogonal to each other, so that signals from servo pits and guide grooves that are offset from the track center can be detected. I have to. That is, the solid immersion lens can be arranged with respect to the magneto-optical recording medium such that the radius of curvature in the track direction of the magneto-optical recording medium is small, so that the light spot becomes substantially elliptical and the major axis of the ellipse is large. Is in the track width direction of the magneto-optical recording medium.

The curved surfaces of the lenses have different radii of curvature r in the lens sections including the optical axis and orthogonal to each other.
When it has 1 and r2, it may include a case where one r is infinite, that is, a semi-cylindrical (kamaboko-shaped) lens.

According to a third aspect of the present invention, in a magneto-optical head for reproducing information from a magneto-optical recording medium having an information recording layer, the reproducing light is focused on the magneto-optical recording medium and irradiated. A solid-state immersion lens, a coil for generating a magnetic field, and a yoke for guiding the magnetic field generated from the coil, the yoke being disposed between the light incident surface and the light exit point of the solid-state immersion lens. A magneto-optical head is provided, wherein

In the magneto-optical head of the present invention, the electromagnet is provided immediately above the solid immersion lens, and a yoke is formed inside the solid immersion lens along the optical axis, so that the magnetic flux generated from the electromagnet can be transferred to the solid immersion lens. Can be guided to a recording medium immediately below the recording medium. If the solid immersion lens having the yoke is mounted on the magneto-optical head, an external magnetic field can be generated without forming a magnetic coil in the slider, so that the magneto-optical head can be further miniaturized. it can.
Further, in the present invention, a predetermined distance is provided between the bottom surface and the yoke so that the laser light can be focused on the center of the bottom surface of the solid immersion lens, and the diameter of the yoke is increased from the light incident surface toward the light exit point. It is preferable to make the shape such that the diameter becomes thinner. The solid immersion lens having such a structure is
For example, a yoke portion is inserted in advance during molding, or a yoke is inserted after molding, or a hole for inserting a yoke is formed in a central portion of a hemispherical lens, and a yoke is inserted into the hole. It can be formed by a method such as insertion. In order to generate a stronger external magnetic field from the yoke, it is preferable to dispose a coil on the bottom surface of the solid immersion lens. The polarity of the external magnetic field is controlled by controlling the polarity of the current flowing through the electromagnet.

According to a fourth aspect of the present invention, in a magneto-optical head for reproducing information from a magneto-optical recording medium having an information recording layer, reproduction light is focused on the magneto-optical recording medium and irradiated. A solid magnetic immersion lens, a coil for generating a magnetic field, and a linear magnetic material made of a soft magnetic material for guiding the magnetic field generated from the coil, wherein the linear magnetic material is A magneto-optical head is provided, which is formed on the optical axis of an immersion lens.

In the magneto-optical head of the present invention, a linear magnetic material is formed on the solid immersion lens along the optical axis, and a coil is wound around the linear magnetic material to flow an electric current to generate an external magnetic field. Can be generated. In this case, it is preferable that the coil is arranged at a position that does not block the optical path of the laser light. With this configuration, since an external magnetic field is applied with a small magnetic flux, it can be used as an external magnetic field for high-density recording. Also, since less power is consumed, an external magnetic field can be efficiently applied to the recording medium. When recording information on an optical recording medium, it is necessary to switch the polarity of the external magnetic field at high speed in accordance with the recorded information. Therefore, a linear magnetic material has a soft magnetic property in which the spin direction is switched at high speed. A material is preferable, and for example, a permalloy or an amorphous soft magnetic material is preferable.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments and examples of a magneto-optical head and a magneto-optical recording / reproducing apparatus according to the present invention will be described with reference to the drawings.

Embodiment 1 FIG. 1 shows a specific example of a flying type magneto-optical head 100 according to the present invention. The flying type magneto-optical head 100 includes a solid immersion lens 10 and a magnetic coil 4 for applying an external magnetic field on a slider 2. The slider 2 has a through hole 2a having substantially the same diameter as the outer periphery of the solid immersion lens 10, and the solid immersion lens 10 is fitted in the through hole 2a. The magnetic coil 4 extends through the through hole 2 a of the slider 2 so as to surround the outer periphery of the solid immersion lens 10.
It is buried above. The slider 2 is connected to an actuator of a magneto-optical recording / reproducing apparatus described later via a support mechanism using a leaf spring (not shown). With such a support mechanism, the solid immersion lens 10
Are arranged so that the bottom surface of the solid-state immersion lens 10 extends parallel to the magneto-optical recording medium 3 and the leakage magnetic field from the magneto-optical recording medium 3 reaches the bottom surface of the solid immersion lens 10.

As shown in FIG. 1A, on the bottom surface of the solid immersion lens 10, a reproducing film 61, which is a perpendicular magnetization film made of GdFeCo, is formed with a thickness of about 20 to 30 nm. The magnetization of the reproducing film 61 is set in advance in the erasing direction (↓).
Has been initialized to be. The lower surface of the reproduction film 61 matches the height of the bottom surface of the slider 4. The magneto-optical recording medium 3 has a structure suitable for reproduction by the magneto-optical head 100 of the present invention, and a SiN dielectric layer 53 and a T
bFeCo recording layer 55 and SiN dielectric layer (protective layer) 5
7 is provided. It is assumed that information is recorded in the recording layer 55 in advance by a magnetic field modulation recording method or the like. Note that SiN
A carbon protective layer or a lubricant may be provided on the dielectric layer (protective layer) 57. However, the total film thickness on the recording layer 55 is preferably set to about 10 nm so that the leakage magnetic field from the recording layer 55 can reach the reproducing film 61.

The principle and operation of reproduction using the magneto-optical head 100 having the above structure will be described below. A laser beam for reproduction is irradiated from above the solid immersion lens 10 and is focused on the bottom surface of the solid immersion lens 10. Evanescent light is generated from the bottom surface of the solid immersion lens 10, and heats an extremely narrow region 61a of the reproducing layer 61 as shown in FIG. In the heated region, particularly in the central high-temperature portion irradiated with the evanescent light, the coercive force of GdFeCo decreases, and the magnetization is reversed by the leakage magnetic field from the magnetic domain 55a of the recording layer 55 immediately below. Magnetic domains 61a are generated. This magnetic domain 61a can be regarded as a transfer of the magnetic domain 55a of the recording layer 55. This transferred magnetic domain 61a
Is detected by evanescent light generated from the bottom surface of the solid immersion lens 10. Thereby, the recording layer 5
Five extremely small magnetic domains 55 a can be independently reproduced through the reproduction layer 61.

Further, according to the present invention, the reproducing layer 61 has a MAM
A function as a MOS layer can be provided. That is, when a magnetic field in the same direction as the magnetization direction of the magnetic domain 55a of the recording layer is applied by the magnetic coil 4, the magnetic domain 61a transferred to the reproducing layer 61 becomes the reproducing layer 61 as shown in FIG.
The enlarged magnetic domain 61a is formed by enlarging in the plane of FIG. By reading out the expanded magnetic domain 61b with evanescent light, an increased reproduction signal can be obtained.

Although the magneto-optical head 100 shown in FIG. 1 has the magnetic coil 4, a thin-film magnetic coil may be mounted on the light exit surface of the solid immersion lens 10. The thin-film magnetic coil can be formed by exposing and developing a photoresist in a predetermined pattern using photolithography, and depositing a metal layer. After the thin-film magnetic coil is formed on the light exit surface of the solid immersion lens 10, the reproducing layer 61 can be formed by sputtering or vapor deposition.

Embodiment 2 FIG. 2A shows a specific example of a solid immersion lens used in the magneto-optical head of the present invention. Although this solid immersion lens 60 is substantially hemispherical, the radius of curvature r2 in the X-axis direction is larger than the radius of curvature r1 in the Y-axis direction in the figure. That is, the center of curvature Oy of the lens cross section cut along a plane including the Y axis and the Z axis (optical axis of the lens) is located at a position where the Z axis intersects the bottom surface of the lens, while a plane including the X axis and the Z axis. The center of curvature Ox of the cut lens cross section exists below Oy on the Z axis. Solid immersion lens 6 of this shape
The bottom surface of 0 is flat, the radius of the short axis is r1, and the radius of the long axis (r3) is slightly shorter than r2.

Such a solid immersion lens 60
Is conceptually shown in FIG. 2B in the case where is disposed on the magneto-optical recording medium 3. As shown in the drawing, the solid immersion lens 60 is arranged such that the short axis side of the elliptical bottom surface is parallel to the track. And the optical axis O of the lens
Is located at the center of the track 64 of the magneto-optical recording medium 3. The radius r1 in the minor axis direction of the bottom surface of the lens is substantially half of the track pitch, but the radius r1 in the major axis direction is
Since 3 is longer than that, the long side portion of the lens bottom surface protrudes in the track width direction. Here, reproduction light having a spot size (diameter) substantially equal to the track pitch is applied from above the lens along the Z axis to the solid immersion lens 6.
When the light is incident on 0, this light is collected on the bottom surface of the lens. However, since the curvature of the lens is different between the X direction and the Y direction, a spot LS elongated in the track width direction is formed as shown by a broken line in FIG. The spot LS passes on guide grooves 64 a and 64 b defining both ends of the track 64. Accordingly, a tracking signal can be obtained by detecting the reflected light from the spot LS. Although not shown, even when wobble pits exist on both sides of the center of the track, wobble pits can be detected from the spot LS.

On the other hand, since the reproducing light spot LS is sufficiently focused in the track direction (linear direction), even when the recording density in the linear direction becomes extremely high, the recording magnetic domain is irradiated separately. The reproduction signal can be extracted therefrom. That is, even in the case of an optical recording medium such as a magneto-optical recording medium recorded at an extremely high density, it is possible to individually detect recording marks such as recording domain axes while detecting a tracking signal.

Further, by mounting the reproducing layer of the first embodiment on the bottom surface of the solid immersion lens 60 of the present embodiment, it is possible to detect a recording mark recorded at a high density in the linear direction with an amplified signal intensity. .

Further, as a modified example of the solid immersion lens 60, it is possible to use a semi-cylindrical lens as shown in FIG. 2C. In this case, the radius of curvature of the lens section cut along a plane including the Y axis and the Z axis is infinite.

Embodiment 3 Next, an example of the configuration of a magneto-optical recording / reproducing apparatus in which the solid immersion lens of the present invention is mounted on a floating type magneto-optical head will be described with reference to FIG. The magneto-optical recording / reproducing apparatus mainly includes a floating magneto-optical head 11, an objective lens 12,
First polarizing beam splitter (hereinafter referred to as PBS) 1
3, laser generator 14, phase plate 15, λ / 2 plate 16, second PBS 17, photodetectors 18, 19, MO signal detection unit 20, head position control unit 21, external magnetic field application control unit 22
It consists of. The solid-state immersion lens 10 of the present invention having a yoke is mounted on the flying type magneto-optical head 11. FIG. 4 shows a schematic configuration of the solid immersion lens 10 in which the yoke 33 is formed. Yoke 33
Is formed along the optical axis of the solid immersion lens 10 and has a shape narrowed down from the light incident surface to the light exit surface of the solid immersion lens 10. The solid immersion lens 10 is obtained by previously inserting a yoke having the above-mentioned shape during molding. An electromagnet 31 for generating a magnetic field is disposed immediately above the solid immersion lens 10, and a circular coil 35 for further increasing the magnetic field from the yoke 33 is formed on the bottom surface of the solid immersion lens 10. The center of the coil 35 is the solid immersion lens 10
Coincides with the center of the bottom surface. Electromagnet 31 and coil 3
The magnetic flux generated by applying a current to 5 is guided by the yoke and generates an external magnetic field in the vertical direction. The polarity of the external magnetic field is controlled by the external magnet
And the polarity of the current flowing through the coil 35 is controlled.

The magneto-optical recording / reproducing apparatus configured as described above records information on the magneto-optical recording medium 30 as follows. The magneto-optical recording medium 30 mounted on a turntable (not shown) is rotated, and the floating type magneto-optical head 11 and the objective lens 12 are moved to a desired data recording area of the magneto-optical recording medium 30 by the head position control unit 21. Let it. Next, a pulsed laser beam is emitted from the laser generator 14 to the magneto-optical recording medium 30 in accordance with a drive signal from a laser drive unit (not shown). The emitted laser light is the first P
The light passes through the solid immersion lens 10 of the flying type magneto-optical head 11 through the BS 13 and the objective lens 12 and is irradiated onto the data recording area of the magneto-optical recording medium 30. By using the solid immersion lens 10, the spot diameter on the magneto-optical recording medium 30 can be made smaller than the minimum spot obtained in the air. By this laser beam irradiation, the recording layer in the data recording area of the magneto-optical recording medium 30 is heated to a Curie temperature at which the magnetization can be reversed by an external magnetic field. The external magnetic field application control unit 2 is synchronized with the laser beam irradiation timing.
By controlling the current flowing through the electromagnet 31 and the coil 35 in accordance with the recording information in step 2, an external magnetic field corresponding to the recording information is generated from the yoke 33 and applied to the magneto-optical recording medium 30.

The magneto-optical recording / reproducing apparatus reflects the irradiated laser beam on the magneto-optical recording medium 30 and returns the reflected laser beam to the first PBS 13 via the objective lens 12. The return light is directed to the phase plate 15 by the first PBS 13.
The return light passes through the phase plate 15 and the λ / 2 plate 16 and is then split by the second PBS 17 in the direction of the photodetectors 18 and 19. The photodetectors 18 and 19 convert the amount of the divided light into an electric signal. Detection signals from the detectors 18 and 19 are supplied to a head position control unit 21. Head position control unit 21
Supplies a control signal for the position of the flying magneto-optical head 11 to an actuator (not shown). The actuator moves the flying magneto-optical head 11 to a desired position while finely adjusting it in accordance with the control signal.

At the time of reproducing information, the objective lens 12 is roughly moved to a position near a desired address while rotating the magneto-optical recording medium 30. Thereafter, the laser generator 14 emits a laser beam, which is weaker than the intensity of the laser beam irradiated during recording, to the magneto-optical recording medium 30. The laser beam emitted from the laser generator 14 to the magneto-optical recording medium 30 forms the above-mentioned small spot on the magneto-optical recording medium 30 and the reflected light from the magneto-optical recording medium 30 emits the second PBS 1 in the same manner as during recording.
7 is supplied. The second PBS 17 splits the reflected light into two according to the direction of the recorded magnetic field. The reflected light is subjected to photoelectric conversion by the photodetectors 18 and 19, and the amount of reflected light is detected. Detection signals from the photodetectors 18 and 19 are supplied to an MO signal detection unit 20 and a head position control unit 21. The head position control unit 21 outputs a position control signal of the flying type magneto-optical head 11 to the actuator in the same manner as during recording. Further, the MO signal detection unit 20 includes the photodetector 18,
MO obtained by performing an operation based on the detection signal at step 19.
Output the playback signal.

Embodiment 4 In the magneto-optical recording apparatus of Embodiment 3, instead of the solid immersion lens having a yoke formed therein, a solid immersion lens having a linear magnetic material as shown in FIG. 5 formed therein is used. It can be used for a floating type magneto-optical head.
FIG. 5 is a schematic configuration diagram of a solid immersion lens having a linear magnetic body 41 formed therein. The linear magnetic body 41 is
It is made of permalloy and is formed along the optical axis of the solid immersion lens 10. Linear magnetic body 4
A coil 43 is wound around 1, and a magnetic field is generated by passing a current through the coil 43. Linear magnetic body 4
The coil 43 for magnetizing 1 is arranged at a position that does not block incident light. The current flowing through the coil 43 is controlled by the external magnetic field application controller 22 according to the recorded information. By using the magneto-optical head having such a configuration, a minute recording magnetic domain can be formed.

Although the present invention has been described with reference to the embodiment, the present invention is not limited to the above-described embodiment. In the above embodiment, the case of high-density recording / reproducing on the magneto-optical recording medium using the magneto-optical field modulation method has been described. However, the present invention is not limited to this. And a light modulation method of changing the light intensity according to input information. In the magneto-optical recording / reproducing apparatus shown in FIG. 3, the flying magneto-optical head shown in the first and second embodiments can be used. In the third and fourth embodiments, the external magnetic field generated from the yoke or the linear magnetic material is, for example, MS
It may be used as an external magnetic field for reproduction for reproducing a magneto-optical recording medium of R or MAMMOS.

[0044]

According to the magneto-optical head of the present invention, since the reproducing layer is provided on the bottom surface of the solid immersion lens disposed on the slider, even if extremely small magnetic domains are recorded on the information recording layer. In addition, the minute magnetic domains can be transferred to the reproducing layer while being distinguished from other minute magnetic domains, and good reproduction can be performed even in a magneto-optical recording medium on which ultra-high density recording is performed. In addition, by using a magnetic domain expansion reproduction film for MAMMOS reproduction as a reproduction layer formed on the bottom surface of the solid immersion lens, the minute magnetic domain recorded in the information recording layer is expanded by the magnetic domain expansion reproduction film, and the magnetic domain expansion reproduction film is enlarged. To obtain an amplified reproduction signal. As a result, it is possible to reproduce minute magnetic domains recorded at high density with high resolution and high sensitivity.

Further, in the magneto-optical head of the present invention, the solid immersion lens is not a perfect hemisphere, and the curved surface of the lens has different radii of curvature r1 and r2 in a lens cross section including the optical axis and orthogonal to each other. With such a configuration, it is possible to detect signals from servo pits and guide grooves located at positions deviated from the track center.

In the magneto-optical head of the present invention, since a linear magnetic material or yoke made of a soft magnetic material is formed inside the solid immersion lens, it is generated from an electromagnet or coil for applying an external magnetic field. By guiding the magnetic field to the surface of the magneto-optical recording medium through a yoke or a linear magnetic material, it is easy to control the magnetic flux passing through the spot portion of the laser beam, which is important for high-density recording, and to apply the magnetic flux stably. Can be. By controlling the magnetic flux and irradiating the recording laser beam, input information can be accurately recorded on the recording medium even if the recording density of the recording medium is increased.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams illustrating a magneto-optical head used in Embodiment 1 of the present invention and a principle of reproduction by the magneto-optical head. FIG. 1A shows a state in which magnetization information of a recording layer is transferred to a reproduction magnetic layer.
(B) shows how magnetic domain expansion reproduction is performed using MAMMOS.

FIGS. 2A and 2B are diagrams showing a solid immersion lens of a magneto-optical head used in Embodiment 2 of the present invention, wherein FIG.
(B) shows how tracking and information reproduction are performed using a solid immersion lens, and (C) shows another embodiment of the solid immersion lens according to the present invention.

FIG. 3 is a schematic configuration diagram of a magneto-optical recording / reproducing apparatus provided with the magneto-optical head of the present invention.

FIG. 4 is a schematic configuration diagram of a solid immersion lens provided with a yoke according to the present invention.

FIG. 5 is a schematic configuration diagram of a solid immersion lens provided with a linear magnetic body made of a soft magnetic material of the present invention.

FIG. 6 is a conceptual diagram illustrating an image forming principle of an optical element used in a magneto-optical head according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 optical element 2 slider 3 magneto-optical recording medium 4 magnetic coil 10 solid immersion lens 33 yoke 55 recording layer 61 reproducing layer

Continued on the front page (72) Inventor Norio Ota 1-88 Ushitora, Ibaraki City, Osaka Prefecture Inside Hitachi Maxell Co., Ltd. (72) Inventor Akiyoshi Ito 123-1 Kotani, Matsudo-shi, Chiba Prefecture (72) Inventor: Oki Nakagawa II 603 Higashi Koiwa, Higashi Koiwa 6-chome, Edogawa-ku, Tokyo

Claims (11)

[Claims] 1. A magneto-optical head for reproducing information from a magneto-optical recording medium having an information recording layer, comprising: a solid immersion lens for converging and irradiating the magneto-optical recording medium with reproduction light; A magneto-optical head comprising: an information reproducing magnetic film fixed to a light exit surface of a solid immersion lens. 2. The magneto-optical head according to claim 1, wherein the information reproducing magnetic film is a magnetic domain expansion reproducing film capable of expanding a magnetic domain under an external field. 3. The magneto-optical head according to claim 1, wherein a magnetic coil is formed on a light exit surface of the solid immersion lens. 4. The information reproducing apparatus according to claim 3, wherein at the time of reproducing information, the recording magnetic domain of the information recording layer is transferred to the information reproducing magnetic film, and the transferred magnetic domain is enlarged by a magnetic field generated from the magnetic coil. The magneto-optical head as described in the above. 5. A magneto-optical head for reproducing information from a magneto-optical recording medium having an information recording layer, wherein a solid immersion lens for condensing and irradiating the magneto-optical recording medium with reproduction light is used. A magneto-optical head, wherein a curved surface of the solid immersion lens has different radii of curvature r1 and r2 in lens cross sections including the optical axis and orthogonal to each other. 6. The magneto-optical head according to claim 5, wherein the solid immersion lens is disposed with respect to the magneto-optical recording medium such that a radius of curvature in the track direction of the magneto-optical recording medium is reduced. . 7. A light spot irradiated on a magneto-optical recording medium by a solid immersion lens is elliptical, and a major axis of the ellipse is in a track width direction of the magneto-optical recording medium. 3. The magneto-optical head according to claim 1. 8. A magneto-optical head for reproducing information from a magneto-optical recording medium provided with an information recording layer, comprising: a solid immersion lens for converging and irradiating the magneto-optical recording medium with reproduction light; And a yoke for guiding a magnetic field generated from the coil, wherein the yoke is formed between a light incident surface and a light exit point of the solid immersion lens. Magneto-optical head. 9. The magneto-optical head according to claim 8, wherein the diameter of the bottom surface of the yoke is smaller than the diameter of the upper surface. 10. The magneto-optical head according to claim 8, wherein a bottom surface of the yoke is included in a solid immersion lens. 11. A magneto-optical head for reproducing information from a magneto-optical recording medium having an information recording layer, comprising: a solid immersion lens for converging and irradiating the magneto-optical recording medium with reproduction light; And a linear magnetic body made of a soft magnetic material for guiding a magnetic field generated from the coil. The linear magnetic body is formed on the optical axis of the solid immersion lens. 1. A magneto-optical head, comprising: