JP2001312830A - Optical pickup, optical disk device and focus adjusting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately record or reproduce signals even by using proximity light. SOLUTION: The optical pickup 1 is equipped with an SIL2 which is arranged closely to an optical disk 200 and which write and/or reads signals for the optical disk 200 by means of light entering from a light source (optical fiber 9) and with a focus adjusting means 6 for varying the parallelism of the light entering into the SIL 2. The focus adjusting means 6 is provided with a lens 7 freely movable on the optical axis and with a lens position moving means 8 for displacing the position of the movable lens 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup for writing and / or reading signals to and from a signal recording medium, and an optical disk for recording and / or reproducing signals to and from a signal recording medium using such an optical pickup. The present invention relates to an apparatus and a focus adjustment method for adjusting focus.

[0002]

2. Description of the Related Art In recent years, there has been proposed a technique for recording and reproducing signals on and from an optical disk by using near-field light in order to cope with an increase in the density of an optical disk. For example, there is a technique of performing signal writing (near-field recording) on an optical disk by using light bleeding, so-called evanescent light, in a near field. Incidentally, the objective lens used in such a case usually has a numerical aperture NA.
Is one or more, and is mounted on an optical pickup or the like.

FIGS. 10 and 11 show an objective lens capable of storing and reproducing in near-field light.

A lens 100 shown in FIG. 10 is a so-called SIL (Solid Immersion Lens) including a first lens 101 and a second lens 102 and configured as a combined lens.

The first lens 101 has convex surfaces on both sides, a first surface 101a as a light incident surface, and a second surface 101b as a light exit surface for the second lens 102. I have.

[0006] The second lens 102 is
A third surface 10 whose surface facing 1 is a substantially spherical convex surface
2a, the fourth surface 102 having the other surface substantially flat.
b. The fourth surface 102b is the optical disk 20
0, and the distance between the fourth surface 102b and the optical disc 200 is 100 nm or less (for example, 50 nm).
nm) so that the SIL 100 is
00.

In such an SIL 100, a laser beam L from a light source (not shown) is first applied to a first lens 101.
Incident on the first surface 101a of the first lens 1
01, and is emitted from the second surface 101b toward the second lens 102. The laser light L from the light source is emitted as convergent light toward the second lens 52 by being transmitted through the first lens 101 in this manner.

The laser light L emitted from the second surface 101b of the first lens 101 is applied to the third lens 101 of the second lens 102.
From the surface 102a of the optical disk 200 and is focused on the fourth surface 102b facing the optical disc 200. And the fourth
A signal can be written to or read from the optical disc 200 by so-called bleeding of the laser beam focused on the surface 102b.

[0009] As described above, the SIL 100 is configured as a group lens, and utilizes the near-field light to generate an optical disc 20.
Writing and reading of a signal with respect to 0 are enabled.

On the other hand, the lens 110 shown in FIG. 11 is a so-called SIM (Solid Immersion Mirror) in which the same performance as the SIL 100 is realized by a single lens configuration. This SIM 110 is also called a catadioptric lens.

The SIM 110 includes a first surface 110a having a concave spherical or aspherical shape, a second surface 110b having a planar shape, and a third surface 110c having a convex spherical or aspherical shape. Have.

Then, the second surface 110b and the third surface 1
On 10c, reflection films 111 and 112 are formed.
Thereby, the second surface 110b functions as a plane mirror surface for the light incident on the SIM 110, and the third surface 110c has a concave shape for the light incident on the SIM 110. Functions as a mirror surface of The reflection films 111 and 112 are formed of, for example, an Al film or the like.

The SIM 110 has a second surface 110.
A convex surface 110d having a convex shape is formed substantially at the center of b. The convex surface 110d is a condensing surface for laser light.

In such a SIM 110, a laser beam L from a light source first enters from a first surface 110a, is reflected by a second surface 110b, and then reflected by a third surface 11a.
The light is further reflected at 0c. Then, the laser light L reflected by the third surface 110c is focused on the convex surface 110d facing the optical disc 200. The so-called bleeding of the laser light condensed on the convex surface 110d enables writing and reading of signals to and from the optical disc 200.

The SIL 100 and SIM 11 as described above
0 is proposed as a lens that enables high-density recording on the optical disc 200.

[0016]

However, in the recording / reproducing technique using near-field light as described above, there is a problem how to reliably concentrate light energy on the surface of a signal recording medium. That is, the recording / reproducing technique using near-field light also has a problem of achieving just focus. For example, when the precision of an optical system in an optical pickup or the like that writes a signal to an optical disk with near-field light or the like is low, just focus becomes difficult.

In a system which has a numerical aperture NA of about 0.6 and a wavelength λ of about 650 nm, such as a so-called DVD, which is currently in practical use, the depth of focus of the objective lens is about ± 0.9 μm, and the far field is large. Since the focus servo is applied, such a problem does not occur.

However, a near-field (near-field) system,
For example, the effective numerical aperture is NA = 1.5, and the wavelength λ is 400 nm.
In the case of, the depth of focus is about ± 0.18 μm. Here, for example, in an optical system of an optical pickup used for writing a signal to a DVD or the like, the accuracy is ± 0.9 u.
m. For this reason, when using an optical system of an optical pickup such as that used for a DVD,
Its precision is much larger than the required depth of focus of ± 0.18 μm in the near field, and it can be said that just focusing is difficult.

On the other hand, it is difficult to manufacture an optical system having such an extremely high precision. Further, such an optical system cannot be said to be excellent in mass productivity. Therefore, it is desirable to improve the near-field technology with the processing accuracy and the assembly accuracy of the components currently mass-produced.

FIG. 12 shows an optical system currently proposed for near-field recording and reproduction. Such an optical system is configured in an optical pickup.

As shown in FIG. 12, the optical system 120 includes an SIL 100 serving as an objective lens, a mirror 121, a collimator lens 122, and an optical fiber 123.
Note that the above-described SIM 110 can be employed as the objective lens.

In such an optical system 120, at the time of reproduction, light emitted as diffused light from the optical fiber 123 is incident on the collimator lens 122, is converted into a parallel light beam by the collimator lens 122, and is emitted toward the mirror 121. You. In the mirror 121, the collimating lens 122
From the SIL 100 toward the SIL 100
At 0, the incident light is condensed on the fourth surface 102b of the second lens 102 via the first lens 101 and the second lens 102 as described above.

Then, the return light enters the optical fiber 123 from the SIL 100 via the mirror 121 and the collimating lens 122.

Such an optical system 120 has been proposed, and it is desired that near-field recording and reproduction can be performed with high accuracy even by using such an optical system that can be mass-produced.

Accordingly, the present invention has been made in view of the above-mentioned circumstances, and an optical pickup, an optical disk device, and a device capable of accurately recording and reproducing signals even in a near field.
And a focus adjustment method.

[0026]

An optical pickup according to the present invention is an optical pickup for writing and / or reading a signal to / from a signal recording medium using near-field light in order to solve the above-mentioned problems. And an objective lens which is disposed close to the signal recording medium and which writes and / or reads a signal to and from the signal recording medium by light incident from the light source, and changes parallelism of light incident on the objective lens. Adjustment means for causing the adjustment to be performed.

In the optical pickup having such a configuration, the focus is adjusted by adjusting the parallelism of light incident on the objective lens configured to be applied to the near field by the adjusting means.

According to another aspect of the present invention, there is provided an optical disc apparatus for recording and / or reproducing signals on a signal recording medium using near-field light. An objective lens which is arranged close to the medium and which writes and / or reads out a signal on and from a signal recording medium which is rotated by the rotary operation means by light incident from the light source; An optical pickup provided with adjusting means for changing the parallelism.

The optical disk device having such a configuration adjusts the focus by adjusting the parallelism of the light incident on the objective lens configured to be applied to the near field by the adjusting means.

Further, in order to solve the above-mentioned problems, a focus adjustment method according to the present invention is arranged close to a signal recording medium, and writes and / or reads a signal to and from the signal recording medium using near-field light. The present invention relates to a focus adjustment method for adjusting a focus in an objective lens, wherein the light incident from a light source is used to write and / or read out a signal from / to a signal recording medium. Adjust the focus by changing the degree.

With such a focus adjustment method, the focus is adjusted by adjusting the parallelism of light incident on an objective lens configured to be applied to a near field.

[0032]

Embodiments of the present invention will be described below in detail with reference to the drawings. In this embodiment, the present invention is applied to an optical pickup for writing and / or reading signals to and from an optical disk. The optical pickup according to the present embodiment is configured to be able to write and read signals to and from an optical disk by using near-field light.

Hereinafter, optical pickups according to first to third embodiments to which the present invention is applied will be described. In addition,
The difference between the optical pickups in the first to third embodiments is the difference in the configuration of the adjusting means for performing the focus adjustment.

First, the optical pickup according to the first embodiment has a so-called first lens 3 as shown in FIG.
And a so-called SIL (Solid Im
mersion lens) 2, mirror 5, focus adjusting means 6, and optical fiber 9.

In such an optical pickup 1,
The SIL 2 is disposed close to the optical disc 200, functions as an objective lens for writing and / or reading signals to and from the optical disc 200 by light incident from a light source (optical fiber 9), and
Functions as adjusting means for changing the parallelism of light incident on the SIL 2.

In the optical pickup 1 configured as described above, light emitted as diffused light from the optical fiber 9 is incident on the lens 7 of the focus adjusting means 6.

The lens 7 is, for example, a biconvex lens and functions as, for example, a collimating lens. The lens 7 emits the light emitted from the optical fiber 9 to the mirror 5 as a parallel light beam.

The lens 7 and the lens position moving means 8 constitute the focus adjusting means 6. The lens 7 is arranged on the optical axis, and can be displaced along the optical axis direction by the lens position adjusting means 8.
The lens position adjusting means 8 makes the lens 7 movable by a stepping motor, for example. The focus is adjusted by displacing the lens 7 by the lens position adjusting means 8. The principle will be described later in detail.

The light emitted from the lens 7 is reflected by the mirror 5 and enters the SIL 2.

In the SIL 2, light enters from the first surface 3 a of the first lens 3, passes through the first lens 3, and travels from the second surface 3 b toward the second lens 4. And is emitted. By being transmitted through the first lens 3 in this manner, the incident light is emitted as convergent light toward the second lens 4.

The light emitted from the second surface 3b of the first lens 3 is incident on the third surface 4a of the second lens 4 and is incident on the fourth surface 4b facing the optical disc 200. It is collected. Optical disc 200 facing fourth surface 4b
Is less than 100 nm (for example, about 50 nm)
The writing and reading of signals to and from the optical disc 200 are performed by so-called bleeding of the light collected on the fourth surface 4b.

As described above, the optical pickup 1 can write and read signals to and from the optical disk 200 using near-field light by the optical system configured as described above.

The optical pickup 1 has a lens 7
The focus adjustment unit 6 including the lens position adjustment unit 8 adjusts the focus of the light condensed on the fourth surface 4b. The adjustment principle will be described with reference to FIG.

For example, as shown in FIG. 2A, light is focused by the objective lens 9 to form a spot. At this time, when the light incident on the objective lens 9 is parallel light, a diffraction-limited spot is formed at a design point (design position).

Therefore, as shown in FIG. 2B, when the light incident on the objective lens 9 is divergent light, the light is converged on the objective lens 9 at a position farther from the design point, and The spot at the point becomes larger. Also, as shown in FIG. 2C, when the light incident on the objective lens 9 is convergent light, the light is condensed at a position closer to the objective lens 9 than the design point. The spot at the point becomes larger.

Here, when the objective lens 9 is considered to be replaced with the first lens 3 of the SIL 2, the following is obtained.

If the SIL 2 is also designed on the assumption that parallel light is incident on the first lens 3, if the parallel light is incident on the first lens 3, as shown in FIG. As shown in (A), the fourth lens 4
Spots are formed on the surface 4a.

When the divergent light is incident on the first lens 3, as shown in FIG. 2B, the condensing position is farther from the design point and the fourth lens 4 Only a spot larger than the diffraction-limited spot is formed on the surface 4a. In this case, a near-field light that forms a diffraction-limited spot on the fourth surface 4a and writes or reads a signal to or from an optical disc degrades a signal to be written or read.

Further, when the convergent light is incident on the first lens 3, as shown in FIG. 2C, the condensing position is closer to the design point, and also in this case, the second lens Only the spot larger than the diffraction-limited spot is formed on the fourth surface 4a of No. 4. Similarly, a signal to be written or read deteriorates.

In view of the above, by providing means for ensuring that the light incident on the first lens 3 is always parallel light, that is, the divergent light which is the incident light ((B) in FIG. 2) Means to make parallel light),
By providing means for converting convergent light (state shown in FIG. 2C) as incident light into parallel light, a diffraction-limited spot is always formed on the fourth surface 4a of the second lens 4. Will be done. If this is generalized, a diffraction-limited spot can be formed on the fourth surface 4a in any case if the luminous flux of the light incident on the SIL 2 can be adjusted. is there.

For example, if there is some error due to the accuracy of the components in the optical system of the optical pickup,
Since the deviation from the original design occurs,
As shown in (B) and (C) in FIG. 2, since the incident light does not become parallel light, a diffraction-limited spot is not formed on the fourth surface 4a. If adjusted, a diffraction-limited spot can be formed on the fourth surface 4a.

The adjustment principle is as described above. The adjustment means constituted by the lens 7 and the lens position adjustment means 8 adjusts light based on the above-described adjustment principle.
The adjustment by the focus adjustment means 6 is specifically as follows.

The lens position adjusting means 8 (not shown) is
As shown in (A), a lens (hereinafter, referred to as the moving lens.) 7 is positioned at a distance L ₁₁ from the end surface 9a of the optical fiber 9. At this time, the light emitted by the moving lens 7 becomes parallel light.

[0054] Further, the lens position adjusting means 8, as shown in FIG. 3 (B), the and the distance to move the lens 7 from the end surface 9a of the optical fiber 9 and closer than the distance L ₁₁ shown in FIG. 3 (A) It is positioned at a distance L _12. Thereby, the moving lens 7
The light emitted from the light becomes divergent light.

[0055] Further, the lens position adjusting means 8, as shown in FIG. 3 (C), the and the distance to move the lens 7 from the end surface 9a of the optical fiber 9 is farther than the distance L ₁₁ shown in FIG. 3 (A) It is positioned at a distance L _13. Thereby, the moving lens 7
The light emitted from is a convergent light.

As described above, the movable lens 7 is moved by the lens position adjusting means 8 to adjust the outgoing light, so that a diffraction-limited spot can always be formed on the fourth surface 4a. Specifically, it is as follows.

In the case where the divergent light is incident on the first lens 3 as shown in FIG. 2B, the light is further transmitted from the optical fiber 9 as shown in FIG. The focus adjustment lens 7 is displaced to a far position. That is,
The light emitted from the moving lens 7 is defined as convergent light. Here, as shown in FIG. 2B, the case where the light incident on the first lens 3 becomes divergent light means, for example, the case where it occurs due to the accuracy of the components of the optical system of the optical pickup 1. No.

By such an operation, the light incident on the first lens 3 is changed into parallel light as shown in FIG. 2A as a result of the cancellation, and the fourth surface 4a
A diffraction-limited spot is formed thereon. That is, incident light having a desired form as designed is incident on the first lens 3.

In the case where convergent light is incident on the first lens 3 as shown in FIG. 2C, as shown in FIG. On the other hand, the moving lens 7 is displaced to a closer position. That is, light emitted from the moving lens 7 is divergent light.

As a result, the light incident on the first lens 3 is changed to parallel light as shown in FIG.
A diffraction-limited spot is formed on the fourth surface 4a.

When parallel light is originally input to the first lens 3 as shown in FIG. 2A, as shown in FIG. The movable lens 7 is located at a position where parallel light is emitted from the lens.

As described above, the focus is adjusted by the movable lens 7, and the adjustment timing is, for example, the adjustment before shipment. Needless to say, the adjustment time is not limited to this.

As described above, the optical pickup 1 can always form a diffraction-limited spot on the fourth surface 4a by displacing the moving lens 7 by the lens position adjusting means 8. . Thus, even if some errors occur due to the accuracy of the components in the optical system of the optical pickup 1, the
A signal can be written or read with respect to 0 without deterioration.

The optical pickup 1 according to the first embodiment has been described above. Next, an optical pickup according to a second embodiment will be described. As shown in FIG. 4, the optical pickup 1 according to the second embodiment has basically the same configuration as the optical pickup 1 according to the above-described first embodiment except for the configuration of the focus adjustment unit 10. Become.

That is, in the optical pickup 1 of the second embodiment, the light emitted as the diffused light from the optical fiber 9 is incident on the focus adjusting means 10. The focus adjustment unit 10 adjusts the incident light so that the light is focused on the fourth surface 4b of the second lens 4 of the SIL 2. The processing in the focus adjustment unit 10 will be described later in detail.

The light adjusted and emitted from the focus adjusting means 10 is reflected by the mirror 5 and enters the SIL 2. In SIL2, as described above, incident light is
The first lens 3 condenses the light as convergent light on the fourth surface 4b of the second lens 4.

As described above, the optical pickup 1 according to the second embodiment uses the near-field light to transmit a signal to the optical disc 200, similarly to the optical pickup 1 according to the above-described first embodiment. Writing and reading can be performed.

Next, the focus adjusting means 10 provided in the second optical pickup 1 will be specifically described.

The focus adjusting means 10 includes three first to third biconvex lenses 11, 12, and 13, and a lens position moving means for moving a lens position.

Although the lens position moving means is not shown, it may be the lens position adjusting means 8 of the focus adjusting means 6 provided in the optical pickup 1 of the first embodiment. For example, the lens position moving means is configured to move the lens by a stepping motor or the like.

Three first to third biconvex lenses 11, 1
Reference numerals 2 and 13 denote lenses having convex surfaces on both sides. The first biconvex lenses 11, 12, and 13 are arranged on the optical path between the optical fiber 9 and the mirror 5 from the optical fiber 9 side. The first to third lenses 11, 12, 13
Functions as a collimating lens as a whole.

In such a configuration, basically, the lens position moving means (not shown) moves any one of the first to third biconvex lenses 11, 12, and 13.
In the present embodiment, a case where a lens moving unit is attached to the third biconvex lens 13 arranged on the mirror 5 side will be described. In this case, the first and second biconvex lenses 11 and 12 are fixed, and the third biconvex lens 13
Are movable along the optical axis direction. Next, a detailed description will be given with reference to FIG.

As shown in FIG. 5A, a lens position adjusting means (not shown) moves the third lens (hereinafter, referred to as a moving lens) 13 to the moving lens 13 and a first biconvex lens (hereinafter, referred to as a moving lens). that the first fixed lens.) 11 second biconvex lens is arranged between the 12 (hereinafter, is positioned a distance L ₂₂ from that.) the second fixed lens. At this time, the light emitted from the moving lens 13 is parallel light.
Note that the first fixed lens 11 and the second fixed lens 12 is a distance L _21, there is a constant (fixed).

[0074] Further, the lens position adjusting means, as shown in FIG. 3 (B), the moving lens 13, is positioned from the second fixed lens 12 at a distance L _23. As a result, the light emitted from the moving lens 13 becomes divergent light.

[0075] Further, the lens position adjusting means, as shown in FIG. 3 (C), the moving lens 13, is positioned from the second fixed lens 12 at a distance L _22. Thereby, the light emitted from the moving lens 13 becomes convergent light.

As described above, the movable lens 13 is moved by the lens position adjusting means to adjust the light, so that the movable lens 13 is always on the fourth surface 4a as in the case of the optical pickup 1 of the first embodiment. Thus, a diffraction-limited spot can be formed.

Specifically, the first lens 3 shown in FIG.
In the case where the divergent light is incident as shown in FIG. 5B, the second fixed lens 12 as shown in FIG.
Then, the focus adjustment lens 13 is displaced to a farther position. That is, light emitted from the moving lens 13 is set as convergent light.

As a result, the light incident on the first lens 3 is changed into parallel light as shown in FIG. 2A as a result of the cancellation, and the diffraction limit is formed on the fourth surface 4a. Spots are formed.

In the case where convergent light is incident on the first lens 3 as shown in FIG. 2C, as shown in FIG. Lens 12
, The moving lens 13 is displaced closer to the position. That is, the light emitted from the moving lens 13 is divergent light.

Thus, the light incident on the first lens 3 is changed into parallel light, and a diffraction-limited spot is formed on the fourth surface 4a as shown in FIG.

Originally, as shown in FIG. 2A, when parallel light is input to the first lens 3, as shown in FIG. The movable lens 13 is located at a position where parallel light is emitted from the movable lens 13.
Position.

As described above, the optical pickup 1 of the second embodiment always forms a diffraction-limited spot on the fourth surface 4a by displacing the moving lens 13 by the lens position adjusting means 10. Will be able to Accordingly, even when a slight error occurs due to the component accuracy in the optical system of the optical pickup 1, it is possible to write and read signals to and from the optical disc 200 without deterioration.

In the above-described second embodiment, the description has been given of the case where the focus is adjusted by moving the position of the third biconvex lens 13 disposed on the mirror 5 side. However, the present invention is not limited to this. Not something. For example, the focus can also be adjusted by moving the first or second biconvex lenses 11, 12.

The optical pickup 1 according to the second embodiment has been described. Next, an optical pickup according to a third embodiment will be described. As shown in FIG. 6, the optical pickup 1 according to the third embodiment is basically the same as the optical pickup 1 according to the above-described first or second embodiment except for the configuration of the focus adjustment unit 20. Configuration.

That is, in the optical pickup 1 of the third embodiment, the light emitted as the diffused light from the optical fiber 9 is incident on the focus adjusting means 20. The focus adjustment unit 20 adjusts the incident light so that the light is focused on the fourth surface 4b of the second lens 4 of the SIL 2. The processing in the focus adjustment means 20 will be described later in detail.

The light adjusted and emitted from the focus adjusting means 20 is reflected by the mirror 5 and enters the SIL 2. In SIL2, as described above, incident light is
The first lens 3 condenses the light as convergent light on the fourth surface 4b of the second lens 4.

As described above, the optical pickup 1 according to the third embodiment is similar to the optical pickup 1 according to the above-described first or second embodiment, and utilizes the near-field light to produce the optical disc 200. Signals can be written to or read from the.

Next, the focus adjusting means 20 provided in the third optical pickup 1 will be specifically described.

The focus adjusting means 20 comprises two first and second biconvex lenses 21, 22 and a biconcave lens 23,
A lens moving means for moving the biconcave lens 23 is provided. For example, the first and second biconvex lenses 21 and 22
The biconcave lens 23 functions as a collimator lens as a whole.

The first and biconvex lenses 21 and 22 are lenses having convex surfaces on both sides. And the biconcave lens 23
Is a lens whose both surfaces are concave. A first biconvex lens 21, a second biconvex lens 22, and a biconcave lens 23 are provided on the optical path between the optical fiber 9 and the mirror 5.
They are arranged in order from the side. Here, the first and second biconvex lenses 21 and 22 are fixed, and the biconcave lens 23 is
It is movable along the optical axis direction.

The lens position moving means is not shown, but may be the lens position adjusting means 8 of the focus adjusting means 6 provided in the optical pickup 1 of the first embodiment. For example, the lens position moving means is configured to move the lens by a stepping motor or the like.

[0092] (not shown) the lens position adjusting means, as shown in FIG. 7 (A), a biconcave lens (hereinafter, referred to as movable lens.) 23, is positioned from the second biconvex lens 22 at a distance L _31. At this time, the light emitted from the moving lens 23 is parallel light. In addition, the first biconvex lens 21 and the second
The distance between them is a predetermined distance,
It is fixed (fixed).

[0093] Further, the lens position adjusting means, as shown in FIG. 7 (B), the movable lens 23, a second biconvex lens (hereinafter, referred to as a second fixed lens.) 22 located at a distance L ₃₂ from Let it. Thereby, the light emitted from the moving lens 23 becomes divergent light.

[0094] Further, the lens position adjusting means, as shown in FIG. 7 (C), the moving lens 23, is positioned from the second fixed lens 22 at a distance L _33. Thereby, the light emitted from the moving lens 23 becomes convergent light.

As described above, the movable lens 23 is moved by the lens position adjusting means to adjust the light, so that the fourth lens is always moved in the same manner as in the optical pickup 1 of the first or second embodiment. A diffraction-limited spot can be formed on the surface 4a.

Specifically, the first lens 3 shown in FIG.
In the case where divergent light is incident as shown in FIG. 7B, as shown in FIG.
, The movable lens 23 is displaced to a farther position. That is, light emitted from the moving lens 23 is set as convergent light.

As a result, the light incident on the first lens 3 is changed into parallel light as shown in FIG. 2A as a result of the cancellation, and the light is diffracted on the fourth surface 4a. Spots are formed.

In the case where convergent light is incident on the first lens 3 as shown in FIG. 2C, as shown in FIG. Lens 22
The movable lens 23 is displaced closer to the position. That is, light emitted from the moving lens 23 is divergent light.

As a result, the light incident on the first lens 3 is changed to parallel light, and a diffraction-limited spot is formed on the fourth surface 4a as shown in FIG.

Originally, as shown in FIG. 2A, when parallel light is input to the first lens 3, as shown in FIG. The movable lens 23 is located at a position where parallel light is emitted from the movable lens 23.

As described above, the optical pickup 1 of the third embodiment always forms a diffraction-limited spot on the fourth surface 4a by displacing the moving lens 23 by the lens position adjusting means 20. Will be able to Accordingly, even when a slight error occurs due to the component accuracy in the optical system of the optical pickup 1, signal writing and reading can be performed on the optical disc 200 without deterioration.

In the above-described embodiment, the optical element is arranged at the subsequent stage of the optical fiber 9 and the optical element is moved to change the parallelism of light. However, the present invention is not limited to this. Not something. For example, by moving the optical fiber 9 along the optical axis direction, the parallelism of light can be changed. In this case, it is necessary to provide an optical fiber position moving means for moving the optical fiber 9 in the optical axis direction.

Next, an optical disk device having such an optical pickup 1 as an optical system will be described.

As shown in FIG.
The optical disk 200 as a signal recording medium is attached to a spindle motor (not shown) provided inside the housing 31, and is fixed by a clamper 32. The optical disc 200 is rotated at a predetermined number of revolutions in accordance with the rotation of a spindle motor driven and controlled by a control circuit.

A voice coil motor 34 for driving, for example, the arm 33 is provided inside the housing 31. Specifically, the arm 33 is rotated by driving the voice coil motor 34. And arm 3
A head support spring 35 is provided integrally with the optical pickup 3, and the optical pickup 1 as described above is attached to the tip of the head support spring 35.

The voice coil motor 34 is composed of, for example, a voice coil attached to the arm 33 and a pair of magnets disposed so as to sandwich the voice coil. An external current is supplied to the voice coil. As a result, a driving force is generated by the current flowing through the voice coil and the magnetic field of the magnet, and the arm 33 and the head support spring 35 are pivoted about the support shaft 36.
Rotate.

Further, light is guided from the optical switching module 37 into the optical pickup 1 via the optical fiber 38 (optical fiber 9), whereby a signal of the optical pickup 1 to the optical disk 200 is transmitted. Writing and reading are performed. The signal processing of a signal written or read by the optical pickup 1 is performed by a signal processing unit (not shown). For example, the signal processing unit
It is composed of an amplifier section, a compression section, a decoding section and the like.

FIGS. 9A to 9C show details of the head support spring 35 and the optical pickup 1. FIG. FIG.
As shown in (A) to (C), an optical pickup (optical head) 1 is attached to one end of a head support spring 35. The optical pickup 1 shown in this example is the one described as the first embodiment described above, in which one biconvex lens 6 is arranged between the mirror 5 and the optical fiber 9 and is moved. Focus adjustment.

The head support spring 35 is formed in a substantially flat plate shape, and is configured to have elasticity in a direction facing the optical disc 200. The optical pickup 1 is attached to the tip (free end) of the head support spring 35.

The optical pickup 1 has a configuration in which a moving lens (focus adjusting lens) 6 and a mirror 5 are housed in a lens barrel 41 having a substantially cylindrical shape, and a first and a second lens constituting the SIL 2. The lenses 3 and 4 are mounted outside the lens barrel 41.

The lens barrel 41 has a substantially cylindrical shape, and is disposed on the free end side of the support spring 35 such that the longitudinal direction substantially coincides with the center axis direction formed by the free end and the support end of the head support spring 35. Installed. The optical fiber 9 is attached to one end of the lens barrel 41, and the mirror 5 is attached to the other end. The movable lens 6 is movably mounted on the optical path of the light emitted from the optical fiber 9 in the lens barrel 41.

Specifically, the tip of the optical fiber 9 is inserted into a fiber folder (fiber top) 42,
The fiber folder 42 is inserted into the lens barrel 41, and the fiber folder 42 is fixed to the lens barrel 41. For example, an adhesive injection hole 41a is provided,
After the fiber folder 42 has been inserted into the housing 1, the lens barrel 41 and the fiber folder 42 are fixed to each other by the adhesive 43 injected from the adhesive injection hole 41 a.

The moving lens 6 is arranged on the optical path between the mirror 5 and the optical fiber 9 arranged in the lens barrel as described above. The movable lens 6 is movable on the optical path, and is displaceable by lens position moving means. For example, although not shown, the lens position moving means is constituted by, for example, a stepping motor or the like. The present invention is not limited to this. For example, the lens position moving unit may be a unit that simply fixes the movable lens 6 that is movable at a predetermined position, for example, a screwing unit. Is also good. Thereby, the lens position moving means can be configured more easily.

The mirror 5 is disposed in the lens barrel 41 at a position facing the optical fiber 9.
The SIL 2 is arranged at a position where the light from the optical fiber 9 reflected by the optical fiber 9 enters through the opening 41 b of the lens barrel 41.

The SIL 2 is attached to the tip of the head support spring 35, and includes the first and second lenses 3 and 4 as described above. For example, SIL
Reference numeral 2 denotes a position where the first and second lenses 3 and 4 are integrated with a so-called slider member 44 and located at the distal end of the head support spring 35.

The slider member 44 is configured to float on the optical disk by using an air flow generated between the slider member 44 and an optical disk (not shown). By utilizing the floating of the slider member 44, the distance between the fourth surface 4b of the second lens 4 of the SIL 2 attached to the slider member 44 and the optical disk is set to 50n.
m can be kept constant.

The optical pickup 1 as described above is attached to the tip of the head support spring 35. As shown in FIG. 8, the optical disc device 30 records and reproduces signals on the optical disc 200 by using the optical pickup 1. Can be.

The optical pickup 1 can write and read signals to and from the optical disc 200 without deterioration even if a slight error occurs due to the accuracy of the components in the optical system. The device 30 can record and reproduce signals without deterioration.

Although the above-described optical disk device 30 has been described as including the optical pickup 1 of the first embodiment, the present invention is not limited to this. For example, the optical disc device 30 may be configured to include the optical pickup 1 according to the second or third embodiment, or may be configured to include the optical pickup 1 whose focus can be adjusted by moving the optical fiber 9. There may be.

[0120]

The optical pickup according to the present invention is disposed close to a signal recording medium, and writes and / or reads a signal to and from the signal recording medium by light incident from a light source. Adjusting means for changing the parallelism of the light incident on the lens, thereby adjusting the parallelism of the light incident on the objective lens configured to be applied to the near field by the adjusting means, thereby adjusting the focus. Can be.

Further, the optical disk device according to the present invention is arranged close to a signal recording medium, and writes and / or reads out a signal from and to a signal recording medium which is rotated by a rotating operation means by light incident from a light source. And an optical pickup including an adjusting means for changing the parallelism of the light incident on the objective lens, so that the light incident on the objective lens configured to be applied to the near field is provided. The focus can be adjusted by adjusting the parallelism by the adjusting means.

Further, according to the focus adjustment method of the present invention, the parallelism of the light incident on the objective lens of the objective lens for writing and / or reading signals to / from the signal recording medium by the light incident from the light source is described. Can be adjusted to change the focus.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an optical pickup according to a first embodiment of the present invention.

FIG. 2 is a diagram used to explain the principle of the present invention.

FIG. 3 is a block diagram illustrating details of a focus adjustment unit of the optical pickup according to the first embodiment.

FIG. 4 is a block diagram illustrating a configuration of an optical pickup according to a second embodiment of the present invention.

FIG. 5 is a block diagram illustrating details of a focus adjustment unit of the optical pickup according to the second embodiment.

FIG. 6 is a block diagram illustrating a configuration of an optical pickup according to a third embodiment of the present invention.

FIG. 7 is a block diagram illustrating details of a focus adjustment unit of the optical pickup according to the second embodiment.

FIG. 8 is a perspective view showing an optical disk device according to an embodiment of the present invention.

FIG. 9 is a plan view, a side view, and a front view showing details of the configuration of a head support spring and an optical pickup in the optical disk device described above.

FIG. 10 is a block diagram illustrating a configuration of an SIL (Solid Immersion Lens).

FIG. 11 is a diagram showing a configuration of a SIM (Solid Immersion Mirror).

FIG. 12 is a block diagram illustrating a configuration of a conventional optical pickup.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Optical pickup, 2 SIL, 6 Focus adjustment means, 7 Moving lens, 8 Lens position moving means

Claims (20)

[Claims] 1. An optical pickup for writing and / or reading a signal to / from a signal recording medium using near-field light, wherein the optical pickup is disposed in proximity to the signal recording medium and receives light incident from a light source. An optical pickup comprising: an objective lens for writing and / or reading a signal to and from the signal recording medium; and an adjusting unit for changing a degree of parallelism of the light incident on the objective lens. 2. The apparatus according to claim 1, wherein the adjusting unit includes an optical element disposed on an optical path of the light emitted from the light source, and a position adjusting unit for adjusting a position of the optical element on the optical path. The optical pickup according to claim 1. 3. The optical pickup according to claim 2, wherein said optical element is a collimating lens. 4. The optical pickup according to claim 2, wherein said optical element comprises a set of biconvex lenses, and said position adjusting means adjusts the position of at least one biconvex lens. 5. The optical element according to claim 2, wherein the optical element comprises a pair of a biconvex lens and a biconcave lens, and the position adjusting means adjusts at least one of the biconvex lens and the biconcave lens. Optical pickup. 6. Between the light source and the objective lens,
A plurality of optical members for guiding light from the light source to the objective lens, wherein the optical element is disposed downstream of the light source without the optical member. 2. The optical pickup according to 2. 7. The optical pickup according to claim 1, wherein the light source is movably provided, and the adjusting means adjusts a position of the light source. 8. The optical pickup according to claim 1, wherein the objective lens is a solid immersion lens (SIL) configured as a set lens. 9. The optical pickup according to claim 1, wherein the objective lens is a SIM (Solid Immersion Mirror) configured as a single lens. 10. An optical disc device for recording and / or reproducing signals on a signal recording medium using near-field light, comprising: a rotation operation unit for rotating the signal recording medium; An objective lens that is arranged and writes and / or reads a signal on and from a signal recording medium that is rotated by the rotation operation means by light incident from the light source; and a parallel light source that is incident on the objective lens. An optical pickup provided with an adjusting means for changing the degree, and processing an optical signal transmitted and received between the optical pickup and the optical pickup to record and / or record a signal on the signal recording medium.
An optical disc device comprising a signal processing unit for performing reproduction. 11. The apparatus according to claim 1, wherein the adjusting unit includes an optical element disposed on an optical path of the light emitted from the light source, and a position adjusting unit for adjusting a position of the optical element on the optical path. 11. The optical disk device according to claim 10, wherein: 12. The optical disk device according to claim 11, wherein said optical element is a collimating lens. 13. The optical disk apparatus according to claim 11, wherein said optical element comprises a set of biconvex lenses, and said position adjusting means adjusts the position of at least one biconvex lens. 14. The optical device according to claim 11, wherein the optical element comprises a set of a biconvex lens and a biconcave lens, and the position adjusting means adjusts at least one of the biconvex lens and the biconcave lens. Optical disk device. 15. An optical system comprising: a plurality of optical members for guiding light between the light source and the objective lens between the light source and the objective lens; wherein the optical element does not pass through the optical member. 12. The light source according to claim 11, wherein the light source is disposed after the light source.
An optical disk device as described in the above. 16. The optical disk device according to claim 10, wherein said light source is provided movably, and said adjusting means adjusts the position of said light source. 17. The optical disk device according to claim 10, wherein the objective lens is a solid immersion lens (SIL) configured as a set lens. 18. The optical disk device according to claim 10, wherein the objective lens is a SIM (Solid Immersion Mirror) configured as a single lens. 19. A focus adjustment method for adjusting a focus in an objective lens which is disposed close to a signal recording medium and writes and / or reads out a signal on and from a signal recording medium using near-field light. Of the objective lens for writing and / or reading signals to and from the signal recording medium by the light thus emitted,
By changing the parallelism of the light incident on the objective lens,
A focus adjustment method comprising adjusting focus. 20. The parallelism of light incident on the objective lens is changed by adjusting the position on the optical path of an optical element arranged on the optical path of light emitted from the light source. The focus adjustment method according to claim 19, wherein