JP2001236680A - Optical pickup device, and coupling lens for optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coupling lens for an optical pickup device and optical pickup device capable of information recording/reproducing well at the time of using a laser light source unit such as a 2 laser 1 package. SOLUTION: Since a collimator 130 has a diffraction pattern which compensates chromatic aberration of a luminous flux from a laser light source 11 with a wavelength λ1, and a luminous flux from a laser light source 112 with a wavelength λ2 on at least one surface, the laser light sources 111 and 112 are unitized, even when a position is fixed so that the two light sources cannot move in a direction along with an optical axis of a condensing optical system separately, by the diffraction effect of the diffraction pattern, the chromatic aberration compensating can be performed, and, thereby, information can be recorded/ reproduced well.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coupling lens for an optical pickup device including a two-laser one-package light source in which two lasers are unitized, and an optical pickup device.

2. Description of the Related Art In recent years, with the practical use of a short-wavelength red semiconductor laser, a DVD (digital versatile disk), which is a high-density optical disk whose size is about the same as that of a conventional optical disk, CD (compact disk), has a large capacity. ) Is under development. In the optical system of an optical information recording / reproducing apparatus using an optical disk or the like as such an optical information recording medium, the spot focused by the objective lens on the recording medium must be reduced in order to increase the recording signal density. Is required. For this reason, the actual situation is that the wavelength of the laser as the light source is shortened and the NA of the objective lens is increased. For example, in an optical pickup device that records and / or reproduces information on a DVD, 635 nm
When the short wavelength semiconductor laser is used as a light source, the numerical aperture NA of the objective lens for condensing the laser light on the optical disk side is set to about 0.6. In addition to CDs and DVDs, optical disks of various standards, for example, CD-Rs (write-once compact disks), MDs (mini disks), and the like have been commercialized and spread. On the other hand, in an optical pickup device that records and / or reproduces information on a CD-R, the wavelength λ of the light source needs to be 780 nm, but in other optical disks, a wavelength other than the specific light source wavelength is used. A light source can be used, and in such a case, the required numerical aperture NA changes according to the light source wavelength λ used. For example, in the case of a CD, the required numerical aperture NA = λ
(Μm) /1.73, required numerical aperture NA for DVD =
It is approximated by λ (μm) /1.06. The numerical aperture (required numerical aperture) referred to in this specification is the numerical aperture of the light-converging optical system viewed from the optical disk side, and the required numerical aperture is the spot size d required on the recording surface of the optical disk and the usage. A numerical aperture calculated from the wavelength λ, and generally NA = 0.8
3 × λ ÷ d.

As described above, there are various optical disks having different thicknesses of transparent substrates, recording densities, operating wavelengths, and the like on the market, but recording and / or reproducing information on each optical disk. Purchasing a dedicated information recording / reproducing device that can perform the above operation places a heavy burden on the user. Therefore, an information recording / reproducing apparatus including a compatible optical pickup device capable of supporting various optical disks has been proposed. As such an optical pickup device, there has been proposed an optical pickup device provided with a focusing optical system corresponding to each of different optical disks, and switching the focusing optical system depending on the optical disk to be reproduced. However,
In this optical pickup device, a plurality of condensing optical systems are required, so that the configuration is complicated and the cost is high, which is not preferable. Therefore, an optical pickup device for reproducing a plurality of optical disks by using one condensing optical system has been proposed.
By the way, as described above, recording information on a CD /
In order to perform reproduction, a laser light source having a wavelength of 780 nm is generally used. On the other hand, in order to record / reproduce information on a DVD, it is necessary to use a laser light source having a wavelength of 635 nm. Here, since a single laser light source for irradiating laser beams of different wavelengths has not been put to practical use yet, it is necessary to provide two laser light sources of different wavelengths in the above-described optical pickup device. When irradiating each laser beam onto an optical disk from two laser light sources via a single condensing optical system, as one mode, by using a beam splitter, two laser sources arranged at different positions are used.
Laser light beams from the two laser light sources can be irradiated onto the optical disk along the optical axis of the focusing optical system. However, in such an embodiment, it is necessary to insert the beam splitter into the optical path, which causes a problem that the optical pickup device becomes large. On the other hand, if the two lasers are arranged in parallel, there is no need to provide a beam splitter, and the optical pickup device can be simplified and reduced in cost. However, when one of the laser beams from the laser light sources arranged in parallel is irradiated along the optical axis of the condensing optical system, the other passes outside the optical axis of the condensing optical system or is collected. The light is obliquely incident on the optical axis of the optical optical system. When the laser light is incident on the condensing optical system in such an abnormal manner, problems such as deterioration of aberration occur. However, if each laser light source is independent, it can be moved separately, so that the position can be optimized and finely adjusted so that aberration performance is good for each laser light source. On the other hand, a so-called two-laser one-package laser light source in which two laser light sources arranged in parallel are integrated into one package has also been developed. By using such a laser light source unit, the optical pickup device can be further simplified and the cost can be reduced. However, in a laser light source unit in which two lasers are packaged in one package, the distance between the individual laser light sources is fixed, so that the laser light source units are separately positioned not only in the direction perpendicular to the optical axis but also in the direction along the optical axis. Adjustment cannot be performed. SUMMARY OF THE INVENTION An object of the present invention is to provide a coupling lens and an optical pickup device for an optical pickup device capable of excellently recording / reproducing information even when a laser light source unit such as a two-laser one-package is used.

An optical pick-up according to claim 1 is provided.
The coupling device comprises a first light source having a wavelength λ1 and a first light source having a wavelength λ2.
Coupling for converting the divergent state of the light beam from the second light source
Optical information recording of glens and the divergent light beam
An objective lens for focusing on the recording surface of the medium;
An optical system, and reflected light and / or transmitted light from the recording surface.
With a detector for detecting, the thickness of the transparent substrate is different
Recording and recording of information on the first and second optical information recording media
And / or optical pickup for information recording and reproduction
In the apparatus, the first light source and the second light source are united.
And the coupling lens has the wavelength λ1.
Color of light flux from light source and light flux from light source of wavelength λ2
Form a diffraction pattern on at least one surface to correct aberrations
It is characterized by doing. The coupling
A lens from the light source of the wavelength λ1 and the wavelength
Diffraction pattern to correct chromatic aberration with light flux from λ2 light source
At least on one side, the first light
A light source and the second light source are unitized, and two light sources
The source can be moved separately in a direction along the optical axis of the collection optics
Even if the position is fixed so that
Chromatic aberration correction can be performed by the diffraction effect of the pattern.
Recording and reproduction of good information.
You. In addition, the unitization means, for example, the first light source and the
The second light source is fixedly stored in one package.
However, the present invention is not limited to this.
It broadly includes the state where it is fixed so as not to be correct.
You. The light source of the first wavelength and the light source of the second wavelength of the present invention
Various types such as blue laser light source and red laser light source
It is possible. Also, there are three light sources having different wavelengths.
If two of the light sources have the above relationship,
Is enough. As a coupling lens, a single lens
Others, such as a diffraction lens that has almost no power with a normal lens
A two-lens combination with a turn-formed plate member,
A cemented lens and a hybrid lens are also conceivable. Mosquito
Glass can also be considered as a material for the coupling lens
However, a resin is preferable for forming a diffraction pattern. Focusing
Some optical systems have mirrors as well as lenses.
Including. The optical pickup device according to claim 2 has a wavelength λ.
Of the luminous flux from the first light source 1 and the second light source having the wavelength λ2.
Coupling lens for changing divergence state, and divergence state
Focuses the converted light beam on the recording surface of the optical information recording medium
A focusing optical system including an objective lens for
A detector for detecting reflected light and / or transmitted light from
And first and second optical information recording devices having different transparent substrate thicknesses.
Information that can be recorded and / or reproduced on a recording medium
In the optical pickup device for information recording and reproduction,
A pulling lens, the first light source or the second light source
Of the light beams emitted from the optical axis of the focusing optical system
The principal ray of the light beam incident from an oblique direction is almost parallel to the optical axis.
It is characterized in that the light is emitted in the direction.
In this specification, the optical axis of the condensing optical system is a cup.
It means the axis passing through the center of the ring lens. Focusing optics
If you have a mirror, etc., the angle of the optical axis according to the reflection angle
Because it changes. The chief ray is defined by the aperture
It means the ray at the center of the restricted beam. The coupling
Lens from the first light source or the second light source
Of the emitted light beam, the light beam is inclined with respect to the optical axis of the focusing optical system.
The principal ray of the light beam incident from
So that one of the light sources
The position where the light beam is not irradiated in the direction along the optical axis of the focusing optical system
Even if the light source is located at
As is on the optical axis of the condensing optical system,
Better information recording / reproduction is possible because the light beam can be irradiated.
It works. The optical pickup device according to claim 3,
The coupling lens has at least one diffraction pattern.
Diffraction effect of such a diffraction pattern because it is formed on the surface
As a result, the light is incident obliquely with respect to the optical axis of the focusing optical system.
The principal ray of the emitted light beam in a direction substantially parallel to the optical axis.
Can be. The optical pickup device according to claim 4,
From a first light source of wavelength λ1 and a second light source of wavelength λ2.
A coupling lens for converting a divergent state of a light beam;
The scattered light flux is collected on the recording surface of the optical information recording medium.
A focusing optical system including an objective lens for emitting light;
A detection method for detecting reflected light and / or transmitted light from the recording surface
And a first light and a second light having different thicknesses of the transparent substrate.
Allows recording and / or reproduction of information on information recording media
Optical pickup device for information recording and reproduction
The coupling lens may be the first light source or the second light source.
Of the light beams emitted from the light source of
Of the light beam obliquely incident on
Have off-axis characteristics to correct off-axis coma
It is characterized by the following. Note that coma is
It is the standard deviation value. Originally, due to the assembly accuracy
Of the condensing optical system in case an axis misalignment occurs.
Off-axis optical properties should be as close as possible to on-axis optical properties.
Design is preferred. However, if the light source is off-axis,
In this case, the principal ray of the luminous flux emitted from the coupling
The lens and the transparent substrate.
This causes a predetermined coma aberration. That
To eliminate this coma with the coupling lens
If the opposite coma can be given,
Light incident obliquely to the optical axis of the optical system
Effectively reduce coma throughout the collection optics
And good information recording / reproduction becomes possible.
The optical pickup device according to claim 5, wherein the first light
If the light source and the second light source are unitized, the structure is
This is preferable because the structure can be simplified and the cost can be reduced.
The optical pickup device according to claim 6 is the optical pickup device having the wavelength λ1.
Divergence of luminous flux from the first light source and the second light source of wavelength λ2
Coupling lens that converts the state
To focus the focused light beam on the recording surface of the optical information recording medium.
A condensing optical system including an objective lens, and a reflection optical system from the recording surface.
And a detector for detecting emitted light and / or transmitted light.
And first and second optical information recording media having different transparent substrate thicknesses.
Information recordable and / or reproducible information on the body
In the optical pickup device for recording / reproducing, the first light
Unitizing the light source and the second light source,
The lens has a light beam from the light source having the wavelength λ1 and a light beam having the wavelength λ2.
Diffraction pattern to correct chromatic aberration with light flux from light source,
The coupling lens is formed on at least one surface.
Is emitted from the first light source or the second light source.
Of the light beam, it enters obliquely with respect to the optical axis of the focusing optical system.
The principal ray of the emitted light beam is emitted in a direction substantially parallel to the optical axis.
It is characterized in that it is. The coupling
The lens is formed by a light beam from the light source having the wavelength λ1 and a wavelength λ2.
Pattern to correct chromatic aberration with light flux from different light sources
Is provided on at least one surface of the first light source.
And the second light source are unitized, and two light sources
Separately move in the direction along the optical axis of the focusing optical system.
Even if the position is fixed so that
Chromatic aberration correction can be performed by the diffraction effect of the pattern.
Recording and reproduction of good information.
You. In addition, the coupling lens may be the first light source or
Is the condensed light of the light flux emitted from the second light source
The chief ray of the light beam that enters obliquely with respect to the optical axis of the
So that it is emitted in a direction that is almost parallel to the axis.
In one of the light sources, the direction along the optical axis of the focusing optical system
Even if it is placed in a position where it does not emit light
The light source is as if on the optical axis of the focusing optics
As described above, since the light beam can be irradiated in the direction of the optical axis,
Good information recording / reproduction becomes possible. The light according to claim 7.
In the pickup device, the coupling lens is a single lens.
Characteristic. An optical pick according to claim 8.
In the up device, the coupling lens is provided only on one surface.
It has a diffraction pattern, and further has a diffraction effect of the diffraction pattern.
Depending on the result, the light enters the optical axis of the condensing optical system obliquely.
The principal ray of the emitted light beam is emitted in a direction substantially parallel to the optical axis.
It is characterized in that it is. Claim 9
In the optical pickup device, the coupling lens is:
Has a diffraction pattern on both sides, the diffraction pattern on both sides
The chromatic aberration is corrected by the diffraction effect, and the light is condensed.
The principal ray of the light beam that enters obliquely with respect to the optical axis of the optical system
The light should be emitted in a direction substantially parallel to the optical axis.
And features. The optical pickup device according to claim 10.
The coupling lens has a diffraction pattern on both sides.
Due to the diffraction effect of the diffraction pattern on one side.
Chromatic aberration correction and diffraction on the other surface
Due to the diffraction effect of the pattern,
In contrast, the principal ray of the light beam obliquely incident is almost parallel to the optical axis
In a different direction.
You. The optical pickup device according to claim 11, wherein the wavelength λ
Of the luminous flux from the first light source 1 and the second light source having the wavelength λ2.
Coupling lens for changing divergence state, and divergence state
Focuses the converted light beam on the recording surface of the optical information recording medium
A focusing optical system including an objective lens for
A detector for detecting reflected light and / or transmitted light from
And first and second optical information recording devices having different transparent substrate thicknesses.
Information that can be recorded and / or reproduced on a recording medium
In the optical pickup device for information recording / reproduction, the first
Light source and the second light source are unitized,
The coupling lens is a light beam from the light source of the wavelength λ1.
Chromatic aberration between the light beam from the light source of wavelength λ2 and
A diffraction pattern is formed on at least one surface, and
The coupling lens is provided for the first light source or the second light source.
Of the luminous flux emitted from the light source,
On the other hand, in the light-collecting optical system of the light beam incident obliquely,
Having an off-axis characteristic that corrects off-axis coma
Features. The coupling lens is used for the wavelength λ1
Of the luminous flux from the light source having the wavelength λ2
Diffraction pattern for correcting chromatic aberration is provided on at least one surface.
Therefore, the first light source and the second light source are united.
And the two light sources are separated from each other by the condensing optical system.
Position is fixed so that it cannot move in the direction along the optical
The diffraction effect of the diffraction pattern
Chromatic aberration correction, thereby providing good information.
Information can be recorded / reproduced. In addition, the coupling
Emits light from the first light source or the second light source.
Out of the luminous flux from the oblique direction with respect to the optical axis of the focusing optical system.
The chief ray of the incident light beam is emitted in a direction substantially parallel to the optical axis.
So that one of the light sources
Arranged at a position where light flux is not irradiated in the direction along the optical axis of the science system
Even if the light source is
The light flux is directed in the direction of the optical axis as if it were on the optical axis of the optical system.
Irradiation enables better information recording / reproduction.
You. In addition, for off-axis light that produces a constant image height, the objective lens
And a certain coma aberration is generated by passing through a transparent substrate.
This coma aberration is reduced by the coupling lens.
If you can give the opposite coma aberration,
For the light beam incident obliquely with respect to the optical axis of the condensing optical system
Effectively reduce coma throughout the collection optics
And good information recording / reproduction is possible.
Become. The optical pickup device according to claim 12, wherein
The wavelength λ1 and the wavelength λ2 have a relationship of λ1 <λ2.
Then, the thickness of the transparent substrate of the first optical information recording medium is set to t1.
And the thickness of the transparent substrate of the second optical information recording medium is t
2 that the relationship t1 <t2 holds.
Characteristic, for example, different recording of CD, DVD, etc.
It is possible to record / reproduce information on a medium.
You. The optical pickup device according to claim 13, wherein
The light beam emitted from the light source 2 is directed to the optical axis of the condensing optical system.
On the other hand, light is incident obliquely. Claim 14
The optical pickup device according to the above, wherein the coupling lens
The divergent light beam incident on the optical axis into a light beam almost parallel to the optical axis.
The collimator is characterized in that Claim 15
The coupling lens for the optical pickup device described
Light from a first light source of length λ1 and a second light source of wavelength λ2
A coupling lens for changing the divergence state of the bundle, and the divergence
Focuses the converted state light beam on the recording surface of the optical information recording medium
A focusing optical system including an objective lens for performing
Detection for detecting reflected light and / or transmitted light from a surface
And second optical information having different thicknesses of the transparent substrate.
Information can be recorded and / or reproduced on the information recording medium
For optical pickup device for reliable information recording and reproduction
In the lens, the coupling lens is the first lens.
Of the luminous flux emitted from the light source or the second light source,
The main part of the light beam incident obliquely with respect to the optical axis of the focusing optical system
Light rays are emitted in a direction almost parallel to the optical axis
It is characterized by being. The coupling lens is in front
The light flux emitted from the first light source or the second light source
That is, light incident obliquely with respect to the optical axis of the condensing optical system.
So that the chief ray of the bundle is emitted in a direction almost parallel to the optical axis
So that one of the light sources is
It is located in a position that does not emit light in the direction along
Even in such a case, such a light source may
Light can be emitted in the direction of the optical axis as if it were on the axis
Therefore, better information recording / reproduction becomes possible. Claim
16. The coupling lens for an optical pickup device according to item 16.
Means that the coupling lens reduces the diffraction pattern.
Since both are formed on one surface, the diffraction pattern
Due to the folding effect, from the oblique direction to the optical axis of the condensing optical system
The chief ray of the incident light beam is emitted in a direction substantially parallel to the optical axis.
I can make it. The optical pickup according to claim 17.
The device coupling lens includes a first light source having a wavelength λ1 and a first light source having a wavelength λ1.
And the divergence state of the luminous flux from the second light source having the wavelength λ2
Coupling lens and the divergent light beam
Objective lens for focusing light on the recording surface of an optical information recording medium
And a condensing optical system comprising: a light reflected from the recording surface;
Or a detector for detecting transmitted light, and a transparent substrate
For the first and second optical information recording media having different thicknesses,
Information recording / reproducing light capable of recording and / or reproducing information
In coupling lenses for pickup devices,
The coupling lens may be the first light source or the second light source.
Of the light beams emitted from the light source
The light beam incident obliquely with respect to the axis is
Have an off-axis characteristic to correct off-axis coma
And features. Originally due to assembly accuracy
The axis of the condensing optical system is prepared in case an axis misalignment occurs.
Make the external optical characteristics as close as possible to the on-axis optical characteristics.
Design is preferred. However, if the light source is off-axis,
In this case, the principal ray of the luminous flux emitted from the coupling
The lens and the transparent substrate.
This causes a predetermined coma aberration. That
To eliminate this coma with the coupling lens
If the opposite coma can be given,
Light incident obliquely to the optical axis of the optical system
Effectively reduce coma throughout the collection optics
And good information recording / reproduction becomes possible.
19. The coupling for an optical pickup device according to claim 18.
The lens includes the first light source and the second light source as a unit.
If it is, the configuration can be simplified and the cost can be reduced
It is also preferable because it can be achieved. The optical picker according to claim 19.
The coupling lens for the coupling device is the first light of wavelength λ1.
The divergence state of the light flux from the light source and the second light source of wavelength λ2.
Coupling lens and the divergent state is converted
Objective for focusing the light beam on the recording surface of the optical information recording medium
A condensing optical system including a lens, and a light reflected from the recording surface.
And / or a detector for detecting transmitted light.
For the first and second optical information recording media having different substrate thicknesses
For recording and / or reproducing information that can record and / or reproduce information
Coupling lens for optical pickup device
And the first light source and the second light source are unitized.
And the coupling lens emits light of the wavelength λ1.
Color collection of the light flux from the source and the light flux from the light source of the wavelength λ2
Form a diffraction pattern on at least one side to correct the difference
And the coupling lens includes the first light source or the first light source.
Is the condensed light of the light flux emitted from the second light source
The chief ray of the light beam that enters obliquely with respect to the optical axis of the
Light should be emitted in a direction substantially parallel to the axis
It is characterized by. The coupling lens has the wavelength λ.
Color of light flux from light source 1 and light flux from light source of wavelength λ2
Has a diffraction pattern on at least one surface to correct aberration
The first light source and the second light source are unitary.
And the two light sources are separately provided to the condensing optical system.
Position is fixed so that it cannot move in the direction along the optical
The diffraction effect of the diffraction pattern
Chromatic aberration correction, thereby providing good information.
Information can be recorded / reproduced. In addition, the coupling
Emits light from the first light source or the second light source.
Out of the luminous flux from the oblique direction with respect to the optical axis of the focusing optical system.
The chief ray of the incident light beam is emitted in a direction substantially parallel to the optical axis.
So that one of the light sources
Arranged at a position where light flux is not irradiated in the direction along the optical axis of the science system
Even if the light source is
The light flux is directed in the direction of the optical axis as if it were on the optical axis of the optical system.
Irradiation enables better information recording / reproduction.
You. 21. The coupling lens according to claim 20, wherein the coupling lens is a single lens.
It is characterized by being. The optical pick according to claim 21.
The coupling lens for the up device is the coupling
The lens has a diffraction pattern on only one surface, and the diffraction pattern
Due to the diffraction effect of the turn, the light of the focusing optical system is further increased.
The principal ray of the light beam that enters obliquely with respect to the axis
It is characterized by emitting in parallel directions
I do. 23. The cup for an optical pickup device according to claim 22.
In the ring lens, the coupling lens is turned on both sides.
Having a folded pattern, the diffraction effect of the diffraction pattern on both sides
With this, chromatic aberration is corrected, and the focusing optical system is
The principal ray of the light beam that enters obliquely with respect to the optical axis is referred to as the optical axis.
It is characterized by emitting light in a direction substantially parallel
And An optical pickup device bracket according to claim 23.
The coupling lens has the coupling lens on both sides.
It has a diffraction pattern and the diffraction pattern on one side
The chromatic aberration is corrected by the diffraction effect, and the other surface is
Due to the diffraction effect of the diffraction pattern at
The chief ray of the light beam that enters obliquely with respect to the optical axis of the
Light should be emitted in a direction substantially parallel to the axis
It is characterized by. An optical pickup device according to claim 24.
Coupling lens comprises a first light source of wavelength λ1 and a wavelength
A light source for converting the divergence state of the light beam from the second light source
A coupling lens and the divergent light beam
An objective lens for focusing light on the recording surface of the information recording medium
A condensing optical system, and light reflected from the recording surface and / or
Having a detector for detecting transmitted light, and a transparent substrate thickness
For the first and second optical information recording media having different
Optical pickup for information recording / reproduction that can record and / or reproduce
A coupling lens for a pickup device,
The first light source and the second light source are unitized.
The coupling lens emits light from the light source having the wavelength λ1.
Chromatic aberration between the light beam and the light beam from the light source having the wavelength λ2 is corrected.
Diffraction pattern is formed on at least one surface, and
The coupling lens may be the first light source or the second light source.
Of the light beams emitted from the light source
Of the light beam obliquely incident on
Have off-axis characteristics to correct off-axis coma
It is characterized by. The coupling lens has the wavelength λ.
1 and a light beam from the light source having the wavelength λ2.
Diffraction pattern to correct chromatic aberration of at least one surface
The first light source and the second light source are
The two light sources are separately separated by the focusing optics
Fixed position so that it cannot move in the direction along the optical axis of the system
Even when the diffraction pattern is
As a result, chromatic aberration can be corrected,
Recording / reproduction of information becomes possible. Also, the coupling
A lens emits from the first light source or the second light source
Out of the luminous flux that is oblique to the optical axis of the focusing optical system.
The principal ray of the light beam incident from it is emitted in a direction almost parallel to the optical axis
So that one of the light sources
Arrange at a position where the light beam is not irradiated in the direction along the optical axis of the optical system.
Even if it is located, such a light source
The luminous flux in such an optical axis direction is on the optical axis of the optical optical system.
Irradiation enables better information recording / reproduction.
Become. In addition, off-axis light that produces a constant image height is
And a certain amount of coma aberration
This coma aberration is reduced by the coupling lens.
Can give the opposite coma aberration to cancel out
For example, light incident obliquely with respect to the optical axis of the condensing optical system
Coma is effectively reduced throughout the collection optics for the bundle
And good information recording / reproduction is possible.
It works. An optical pickup device according to claim 25.
The pulling lens has the wavelength λ1 and the wavelength λ2,
λ1 <λ2, wherein the first optical information recording medium
The thickness of the transparent substrate of the second optical information recording medium is defined as t1.
When the thickness of the body transparent substrate is t2, t1 <t2
Is characterized by the fact that the relationship
Recording / reproduction of information on different recording media such as DVD
Can be performed. An optical pick according to claim 26.
The coupling lens for the up device is the second light source.
The light beam emitted from the light source is oblique to the optical axis of the focusing optical system.
, And is incident. The light according to claim 27.
The coupling lens for the pickup device is
The divergent light beam incident on the ring lens is almost
It is a collimator for converting a parallel light beam. Contract
The coupling lens according to claim 28, wherein the coupling lens has a divergent shape
In a coupling lens for converting a state, the cup
The main part of the light beam incident obliquely to the optical axis of the ring lens
The beam is directed in a direction substantially parallel to the optical axis of the coupling lens.
Is emitted. The coupling wrench
Is the principal ray of the light beam obliquely incident on the optical axis.
Is emitted in a direction substantially parallel to the optical axis.
So that the light source was along the optical axis of the coupling lens
In a position where the light beam is not emitted in the direction
Also, such a light source is as if the coupling lens
A light beam can be emitted in the direction of the optical axis as if it were on the optical axis.
Therefore, better information recording in the optical pickup device
Recording / reproduction becomes possible. A coupling agent according to claim 29.
Glenns form a diffraction pattern on at least one surface
It is characterized by being. 31. The cuprin according to claim 30.
The lens is a coupling lens that converts the divergent state of the luminous flux.
From light sources of at least two different wavelengths
Diffraction pattern to correct chromatic aberration in light beam
Are formed on one surface, and the at least two different
The coupling lens of each light flux of the wavelength
The principal ray of the light beam incident obliquely to the optical axis of
The light exits in a direction substantially parallel to the optical axis of the
And features. The coupling lens has different waves
Diffraction pattern to correct chromatic aberration of light beam from long light source
At least on one side, so that the two light sources
Each in the direction along the optical axis of the coupling lens.
Even if the position is fixed so that it cannot move,
Chromatic aberration can be corrected by the diffraction effect of the diffraction pattern.
And that good information can be recorded / reproduced.
Become. In addition, the coupling lens may have different wavelengths of light.
Of the light flux emitted from the source,
The principal ray of the light beam that enters obliquely with respect to the optical axis is referred to as the optical axis.
It is designed to emit light in a roughly parallel direction,
Light source emits a light beam in a direction along the optical axis of the focusing optical system.
Such a light source, even if it is placed in a non-irradiating position
As if on the optical axis of the focusing optics,
Light can be emitted in the direction of the optical axis to provide better information
Recording / reproduction becomes possible. A coupling according to claim 31.
The lens is a single lens. Claim
The coupling lens described in No. 32 has a diffraction pattern on only one surface.
Having a turn, by the diffraction effect of the diffraction pattern,
Further, from an oblique direction with respect to the optical axis of the coupling lens.
The principal ray of the incident light beam is converted to the optical axis of the coupling lens.
The light is emitted in a direction substantially parallel to. Claim
The coupling lens described in No. 33 has a diffraction pattern on both sides.
Chromatic aberration compensation by the diffraction patterns on both sides.
Positive and the diffraction effect of the diffraction pattern on both sides
Therefore, it is oblique to the optical axis of the coupling lens.
From the coupling lens
The light is emitted in a direction substantially parallel to the axis. Claim
Item 34. The coupling lens described in Item 34 has a diffraction pattern on both surfaces.
Effect of the diffraction pattern on one side
The chromatic aberration is corrected, and the other surface
Due to the diffraction effect of the diffraction pattern, the coupling loss
Forward the chief ray of the light beam incident obliquely to the optical axis of the lens
The light exits in a direction approximately parallel to the optical axis of the coupling lens.
It is characterized by that. Diffraction patterns used in this specification
(Or diffractive surface) refers to the surface of an optical element,
A relief is provided on the surface, and the angle of the light beam is diffracted.
A form (or surface) that has the effect of changing
Where there are areas where diffraction occurs and areas where no diffraction occurs on two optical surfaces
In this case, it refers to a region where diffraction occurs. As the shape of the relief
Is, for example, on the surface of an optical element,
It is formed as a concentric annular zone, and its section is
When viewed from the surface, each annular zone is known to have a saw-tooth shape
Include such a shape. In this specification
In a narrow sense, a coupling lens is an optical pickup.
Divergent light from the light source into almost parallel light flux
The lens or lens group to be converted, but is not limited to this
Not. In this specification, an optical information recording medium (optical
Discs), for example, CD-R, CD-RW, CD-Video, CD-
Various CDs such as ROM, DVD-ROM, DVD-RAM, DVD-R, DVD + RW,
Various DVDs such as DVD-RW, DVD-Video, etc.
Disc-shaped current optical information recording media and next-generation recording media
Also included. On the information recording surface of many optical information recording media
Has a transparent substrate. However, the thickness of the transparent substrate
Is almost zero or there is no transparent substrate
Something exists or has been proposed. For convenience of explanation, the book
It may be described as "through a transparent substrate" in the specification
However, such a transparent substrate has a thickness of zero, that is, it is transparent.
This includes the case where there is no substrate at all. In this specification
Therefore, recording and reproduction of information are information recording as described above.
Recording information on the information recording surface of a recording medium, information recording
Reproducing information recorded on a surface. The present invention
The optical pickup device performs only recording or only reproduction
May be used for recording,
It may be used to perform both raw.
In addition, recording is performed on a certain information recording medium, and other information is recorded.
What is used to reproduce information recording media
May be recorded on a certain information recording medium.
Or playback, recording and recording on another information recording medium.
It may be used for performing reproduction. What
Note that reproduction here includes simply reading information.
It is a thing. The optical pickup device of the present invention
Player or drive, etc., or incorporate them
Audio and AV equipment, personal computers, and other information terminals
And / or image recording and / or playback equipment.
Can be

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. Each lens constituting the optical system for an optical pickup according to the present embodiment has an aspherical surface represented by the following [Equation 1] on at least one optical surface. Here, Z is the axis in the optical axis direction, h is the axis perpendicular to the optical axis, the traveling direction of light is positive, r is the paraxial radius of curvature, κ is the conic coefficient, Ai is the aspherical coefficient, and Pi is the aspherical surface. It is a power number.

(Equation 1) The diffractive surface has a shape represented by a polynomial whose shape is rotationally symmetric with respect to the optical axis, and a shape represented by a polynomial of two axes (X, Y) perpendicular to the optical axis and orthogonal to each other. A diffraction surface represented by a polynomial rotationally symmetric with respect to the optical axis is represented by [Equation 2] as an optical path difference function, and a diffraction surface represented by a polynomial of an axis (X, Y) perpendicular to the optical axis is represented by an optical path. The unit is expressed as mm in accordance with [Equation 3] as the difference function.
However, X, Y, and Z are right-handed rectangular coordinate systems, and the design wavelength of the optical path difference function is 780 nm. FIG. 1 shows such a coordinate system.

(Equation 2)

(Equation 3) (Embodiment 1) [Table 1] shows data relating to the condensing optical system for an optical pickup device including an objective lens and a coupling lens optical system in Embodiment 1. In the lens data shown below, a power of 10 (for example, 2.5 × 10−3) is replaced by E (for example, 2.5 × E−
3). In addition, primary light due to diffraction of a diffraction pattern represented by a rotationally symmetric polynomial means light whose angle changes in a direction converging after diffraction.

[Table 1] The objective lens is composed of a plurality of annular zones (first, second, and third annular zones) in which the surface on the collimator side is concentrically divided, and each annular zone utilizes a plurality of light sources having different wavelengths by using its spherical aberration. The first and third zones are corrected for aberrations within a diffraction limit for a short substrate and the thin substrate for a transparent substrate having a different thickness, and the second zone is diffracted for a thick substrate at a long wavelength. This is a special objective lens whose aberration has been corrected within the limit. Second
D 'of the orbicular zone indicates a distance on the optical axis between the intersection with the optical axis when the shape of the second orbicular zone is extended to the optical axis according to the aspherical shape equation and the surface of the objective lens on the transparent substrate side. ing. This objective lens is designed to maintain good performance when parallel light is incident from the surface on the light source side. As the coupling lens, a HOE collimator made of an olefin-based resin was used. On the surface of the collimator on the objective lens side, a sawtooth-shaped diffraction pattern is provided substantially concentrically with the optical axis. The refractive index of such a material is shown in [Table 2].

[Table 2] FIG. 2 is a graph illustrating the chromatic aberration of the collimator alone according to the first embodiment. FIG. 2 shows that the back focus does not move regardless of the wavelength. 2 of different wavelength
In the case of an optical pickup device using a unit in which the light source is packaged in one package (for example, two lasers in one package),
If a collimator having axial chromatic aberration is used when light sources having different wavelengths have the same position in the optical axis direction, light from at least one light source does not become parallel light after exiting the collimator, and the performance of the entire optical pickup optical system is reduced. Although worse, when the collimator of this embodiment is used, parallel light is emitted from the collimator at both of two different wavelengths, and the performance of the entire optical pickup optical system is kept good. (Embodiment 2) When using light sources of a plurality of wavelengths without using an optical element such as a beam splitter, at least one light source must be installed at a position away from the optical axis. When a conventional collimator is used, the light beam emitted from off-axis becomes a light beam having an inclination with respect to the optical axis after the collimator is emitted,
When the light passes through the objective lens and the transparent substrate, coma aberration is generated, and the performance of the entire condensing optical system is deteriorated. Table 3 shows data related to the collimator of the second embodiment. The collimator has a diffraction grating on the light source side surface. In the collimator of the present embodiment, a light source having a wavelength of 650 nm is installed on the optical axis,
When used in an optical pickup optical system in which a light source having a wavelength of 780 nm is installed at a distance of 0.1 mm from the optical axis, the light from the light source having a wavelength of 650 nm is a zero-order light and a wavelength of 7
By using primary light for a light source of 80 nm, light from both light sources is converted into light parallel to the optical axis after exiting the collimator.

[Table 3] (Example 3) [Table 4] shows data relating to the collimator of Example 3. The collimator has a diffraction pattern represented by a (X, Y) polynomial on the light source side surface. Example 2
As in the case of the collimator described above, the zero-order light is used for a light source with a wavelength of 650 nm on the optical axis, and the primary light is used for a light source with a wavelength of 780 nm 0.1 mm away from the optical axis. Light from the light source can also be emitted as light parallel to the optical axis. Parallel light having a wavelength of 780 nm is emitted from the surface of the collimator opposite to the light source at a diameter of 5 mm.
When the wavefront aberration is calculated and the collimator having the diffraction grating of Example 2 has a standard deviation of 0.1.
Although a coma aberration of 010λ is generated, the collimator of the third embodiment is corrected to 0.000λ by using a diffraction pattern represented by a (X, Y) polynomial instead of the diffraction grating.

[Table 4] (Example 4) [Table 5] shows data related to the collimator of Example 4. The collimator has a diffraction pattern represented by a (X, Y) polynomial on a light source side surface, and has a diffraction pattern represented by a rotationally symmetric polynomial on an optical axis on an opposite surface. ing. By using the first-order diffracted light by the diffraction pattern provided on the surface on the side opposite to the light source, even if the position of the light source of wavelength 650 nm and the light source of wavelength 780 nm are the same in the optical axis direction, the light is emitted from the collimator with respect to the optical axis Parallel light is obtained. The first-order diffracted light by the diffraction pattern provided on the surface on the light source side is 0.1 mm from the optical axis.
It has a function of converting a principal ray of a light beam from a light source having a wavelength of 780 nm installed at a distant position into a ray parallel to the optical axis. Therefore, the collimator of the present embodiment is set at a wavelength of 650 nm.
A light source with a wavelength of 780 nm and a light source with a wavelength of 780 nm are installed in parallel at an interval of 0.1 mm. After the light is emitted, it is converted into light parallel to the optical axis.

[Table 5] Fifth Embodiment [Table 6] shows data relating to the optical pickup optical system of the fifth embodiment. When a conventional collimator is used, the light emitted from the off-axis light source is emitted from the collimator,
When the light beam becomes inclined with respect to the optical axis and passes through the objective lens and the transparent substrate, coma aberration is generated, and the performance of the entire condensing optical system is deteriorated. In the collimator of the present embodiment, the collimator has an off-axis characteristic that corrects coma generated by the objective lens and the transparent substrate when an off-axis light source is used. Light source of wavelength 780nm is 0.1m from optical axis
In an optical pickup optical system installed at a distance of m, the aperture limit is set such that the NA of the transparent substrate becomes 0.45, and the wavefront aberration of the entire optical system is calculated.
Coma is corrected to a standard deviation of 0.001λ or less.

[Table 6] The collimator has a diffraction pattern on only one surface, and chromatic aberration is corrected by the diffraction effect of the diffraction pattern.
And / or the principal ray of the light beam obliquely incident on the optical axis of the condensing optical system may be emitted in a direction substantially parallel to the optical axis, or a diffraction pattern may be formed on both sides of the collimator. Chromatic aberration is corrected by a diffraction effect of the diffraction patterns on both surfaces, and / or a principal ray of a light beam incident obliquely with respect to the optical axis of the condensing optical system is directed in a direction substantially parallel to the optical axis. The collimator may have a diffraction pattern on both surfaces, and the chromatic aberration may be corrected by the diffraction effect of the diffraction pattern on one surface, and the diffraction effect of the diffraction pattern on the other surface. Thereby, the principal ray of the light beam incident obliquely with respect to the optical axis of the condensing optical system may be incident in a direction substantially parallel to the optical axis. FIG. 3 is a schematic diagram showing the optical pickup device of the present embodiment.
In the optical pickup device 100 shown in FIG. 3, the first semiconductor laser 111 and the second
The semiconductor laser 112 is fixed in parallel to form a unit. The collimator 130 can use the first to fifth embodiments. First optical disk (for example, DVD)
Is reproduced, the luminous flux (wavelength 635 or 650 nm) emitted from the first semiconductor laser 111 serving as a light source disposed on the optical axis of the collimator (coupling lens) 130 and the objective lens 160 that constitute the condensing optical system Is transmitted through the beam splitter 230 and the collimator 130 to become a parallel light beam. Further, the aperture is stopped down by the stop 170, and the transparent substrate 2 of the first optical disc 200 is stopped by the objective lens 160.
The light is condensed on the information recording surface 220 via. And
The light flux modulated and reflected by the information pits on the information recording surface 220 passes through the collimator 130 again through the objective lens 160 and the diaphragm 170, and is transmitted to the beam splitter 23.
The light is reflected at 0, is incident on the photodetector 300 via the sensor lens 310, and a read signal of information recorded on the first optical disc 200 is obtained using the output signal. Further, a change in the shape of the spot on the photodetector 300,
A change in light amount due to a change in position is detected, focus detection and track detection are performed, and the objective lens 160 can be moved by the two-dimensional actuator 150 for focusing and tracking. The first semiconductor laser 111 and the second semiconductor laser 112, which are two-laser one package, are fixed and unitized in parallel, and the two light sources cannot move separately in the direction along the optical axis of the condensing optical system. Even when the position is fixed as described above, the chromatic aberration can be corrected. When reproducing a second optical disc (for example, a CD), a light beam (wavelength 780) emitted from the second semiconductor laser 112 as a light source disposed off-axis of the focusing optical system
nm) enters obliquely so as to be substantially coaxial with the optical axis of the collimator 130, and further passes through the collimator 130 to become a substantially parallel light beam. Further, aperture 170, objective lens 160
Is focused on the information recording surface 220 ′ via the transparent substrate 210 of the second optical disc 200. The light flux modulated and reflected by the information pits on the information recording surface 220 ′ passes through the collimator 130 again through the objective lens 160 and the stop 170, is reflected by the beam splitter 230, and enters the photodetector 300. Then, a read signal of information recorded on the second optical disc 200 is obtained using the output signal. Further, by detecting a change in the shape of a spot on the photodetector 300 and a change in the amount of light due to a change in position,
Focus detection and track detection are performed.
The objective lens 160 can be moved by the dimensional actuator 150 for focusing and tracking.
As in the present embodiment, the laser light for DVD to be converged with higher accuracy for information recording is arranged on the optical axis of the condensing optical system by disposing the first semiconductor laser 111 on the optical axis. The CD is not required to converge as accurately as a DVD for recording information, by irradiating in the direction along which the best optical characteristics of the condensing optical system can be exhibited.
Laser light from the second semiconductor laser 112 is obliquely incident on the optical axis of the collimator 130 and then converted into parallel light. When the laser beam from the second semiconductor laser 112 is obliquely incident on the optical axis from outside the axis of the collimator 130, the objective lens 16
If coma is generated in the laser light from the second semiconductor laser 112 that has passed through the collimator 130 so as to cancel out the coma generated when the light passes through 0, the coma can be improved in the entire condensing optical system. Can be corrected.

According to the present invention, even when a laser light source unit such as two lasers and one package is used,
It is possible to provide a coupling lens and an optical pickup device for an optical pickup device capable of excellently recording / reproducing information.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a coordinate system related to an optical path difference function of a diffraction surface of a collimator.

FIG. 2 is a graph showing chromatic aberration of the collimator alone of Example 1.

FIG. 3 is a schematic diagram showing an optical pickup device of the present embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 optical pickup device 111 first semiconductor laser 112 second semiconductor laser 130 collimator 160 objective lens 170 aperture stop 200 first optical disk or second optical disk 300 photodetector

Claims (34)

[Claims] 1. A coupling lens for converting a divergence state of a light beam from a first light source having a wavelength λ1 and a second light source having a wavelength λ2, and a light beam having the divergence state converted is recorded on a recording surface of an optical information recording medium. A light collecting optical system including an objective lens for collecting light, and a detector for detecting reflected light and / or transmitted light from the recording surface; An information recording / reproducing optical pickup device capable of recording and / or reproducing information on / from a second optical information recording medium, wherein the first light source and the second light source are unitized, and the coupling lens is provided. In an optical pickup device, a diffraction pattern for correcting chromatic aberration between a light beam from the light source having the wavelength λ1 and a light beam from the light source having the wavelength λ2 is formed on at least one surface. 2. A coupling lens for converting a divergence state of light beams from a first light source having a wavelength λ1 and a second light source having a wavelength λ2, and a light beam having the divergence state converted to a recording surface of an optical information recording medium. A light collecting optical system including an objective lens for collecting light, and a detector for detecting reflected light and / or transmitted light from the recording surface; In an optical pickup device for information recording and reproduction capable of recording and / or reproducing information on and from a second optical information recording medium, the coupling lens emits light from the first light source or the second light source. An optical pickup device, wherein a principal ray of a light beam incident obliquely with respect to the optical axis of the condensing optical system is emitted in a direction substantially parallel to the optical axis. 3. The optical pickup device according to claim 2, wherein the coupling lens has a diffraction pattern formed on at least one surface. 4. A coupling lens for converting a divergence state of a light beam from a first light source having a wavelength λ1 and a second light source having a wavelength λ2, and a light beam having the divergence state converted is recorded on a recording surface of an optical information recording medium. A light collecting optical system including an objective lens for collecting light, and a detector for detecting reflected light and / or transmitted light from the recording surface; In an optical pickup device for information recording and reproduction capable of recording and / or reproducing information on and from a second optical information recording medium, the coupling lens emits light from the first light source or the second light source. An optical pickup having an off-axis characteristic for correcting an off-axis coma aberration in the condensing optical system of a light beam incident obliquely with respect to the optical axis of the condensing optical system in the collected light beams. apparatus. 5. The optical pickup device according to claim 2, wherein the first light source and the second light source are unitized. 6. A coupling lens for converting a divergence state of a light beam from a first light source having a wavelength λ1 and a second light source having a wavelength λ2, and a recording surface of an optical information recording medium for converting the divergent light beam. A light collecting optical system including an objective lens for collecting light, and a detector for detecting reflected light and / or transmitted light from the recording surface; An information recording / reproducing optical pickup device capable of recording and / or reproducing information on / from a second optical information recording medium, wherein the first light source and the second light source are unitized, and the coupling lens is provided. Has formed on at least one surface a diffraction pattern that corrects chromatic aberration between the light beam from the light source having the wavelength λ1 and the light beam from the light source having the wavelength λ2, and the coupling lens is provided with the first light source or the second light source. From the two light sources Of the light beam, the optical pickup device characterized in that it is a principal ray of the light beam incident obliquely to emit in a direction substantially parallel to the optical axis with respect to the optical axis of the focusing optical system. 7. The optical pickup device according to claim 6, wherein the coupling lens is a single lens. 8. The coupling lens has a diffraction pattern on only one surface, and further, by a diffraction effect of the diffraction pattern, further couples a principal ray of a light beam incident obliquely with respect to an optical axis of the condensing optical system. 8. The optical pickup device according to claim 6, wherein the light is emitted in a direction substantially parallel to the optical axis. 9. The coupling lens has diffraction patterns on both surfaces, chromatic aberration is corrected by a diffraction effect of the diffraction patterns on both surfaces, and the coupling lens is incident obliquely with respect to the optical axis of the condensing optical system. The optical pickup device according to claim 7, wherein the principal ray of the light beam is emitted in a direction substantially parallel to the optical axis. 10. The coupling lens has a diffraction pattern on both surfaces, chromatic aberration is corrected by the diffraction effect of the diffraction pattern on one surface, and the light is condensed by the diffraction effect of the diffraction pattern on the other surface. 8. The optical pickup device according to claim 7, wherein a principal ray of a light beam obliquely incident on the optical axis of the optical system is emitted in a direction substantially parallel to the optical axis. 11. A coupling lens for converting a divergence state of light beams from a first light source having a wavelength λ1 and a second light source having a wavelength λ2, and a light beam having the divergence state converted is recorded on a recording surface of an optical information recording medium. A light collecting optical system including an objective lens for collecting light, and a detector for detecting reflected light and / or transmitted light from the recording surface; An optical pickup device for information recording / reproducing capable of recording and / or reproducing information on / from a second optical information recording medium, wherein the first light source and the second light source are unitized, The coupling lens has at least one surface on which a diffraction pattern for correcting chromatic aberration between a light beam from the light source having the wavelength λ1 and a light beam from the light source having the wavelength λ2 is formed. Light source or the Out of the light beams emitted from the light source, the light beam incident obliquely with respect to the optical axis of the condensing optical system has an off-axis characteristic to correct off-axis coma aberration in the condensing optical system. Optical pickup device. 12. The wavelength λ1 and the wavelength λ2 are λ1
<Λ2, where t1 is the thickness of the transparent substrate of the first optical information recording medium and t2 is the thickness of the transparent substrate of the second optical information recording medium. The optical pickup device according to any one of claims 1 to 11, wherein the following relationship is established. 13. A light beam emitted from the second light source,
13. The optical pickup device according to claim 12, wherein the light is incident obliquely with respect to the optical axis of the condensing optical system. 14. The optical pickup device according to claim 1, wherein the coupling lens is a collimator that converts the incident divergent light beam into a light beam substantially parallel to an optical axis. 15. A coupling lens for converting a divergence state of a light beam from a first light source having a wavelength λ1 and a second light source having a wavelength λ2, and a light beam having the divergence state converted is recorded on a recording surface of an optical information recording medium. A light collecting optical system including an objective lens for collecting light, and a detector for detecting reflected light and / or transmitted light from the recording surface; In a coupling lens for an optical pickup device for information recording / reproducing capable of recording and / or reproducing information on / from a second optical information recording medium, the coupling lens may be the first light source or the second light source. The light beam emitted from the second light source and the principal ray of the light beam obliquely incident on the optical axis of the condensing optical system are emitted in a direction substantially parallel to the optical axis. For optical pickup device Ngurenzu. 16. The coupling lens for an optical pickup device according to claim 15, wherein the coupling lens has a diffraction pattern formed on at least one surface. 17. A coupling lens for converting a divergence state of light beams from a first light source having a wavelength λ1 and a second light source having a wavelength λ2, and a light beam having the divergence state converted to a recording surface of an optical information recording medium. A light collecting optical system including an objective lens for collecting light, and a detector for detecting reflected light and / or transmitted light from the recording surface; In a coupling lens for an optical pickup device for information recording / reproducing capable of recording and / or reproducing information on / from a second optical information recording medium, the coupling lens may be the first light source or the second light source. Out of the light beams emitted from the second light source, the light beam incident obliquely with respect to the optical axis of the light-collecting optical system has an off-axis characteristic that corrects off-axis coma aberration in the light-collecting optical system. Optical pickup device characterized by Coupling lens use. 18. The light source according to claim 15, wherein the first light source and the second light source are unitized.
The coupling lens for an optical pickup device according to any one of the above. 19. A coupling lens for converting a divergence state of a light beam from a first light source having a wavelength λ1 and a second light source having a wavelength λ2, and a recording surface of an optical information recording medium for converting the divergent light beam. A light collecting optical system including an objective lens for collecting light, and a detector for detecting reflected light and / or transmitted light from the recording surface; In a coupling lens for an optical pickup device for information recording and reproduction capable of recording and / or reproducing information on a second optical information recording medium, the first light source and the second light source are unitized. Wherein the coupling lens is formed on at least one surface with a diffraction pattern for correcting chromatic aberration between a light beam from the light source having the wavelength λ1 and a light beam from the light source having the wavelength λ2. ,Previous Of the light beams emitted from the first light source or the second light source, the principal ray of the light beam incident obliquely to the optical axis of the light-collecting optical system is emitted in a direction substantially parallel to the optical axis. A coupling lens for an optical pickup device, comprising: 20. The coupling lens according to claim 19, wherein the coupling lens is a single lens. 21. The coupling lens has a diffraction pattern on only one surface, and further, by the diffraction effect of the diffraction pattern, further couples a principal ray of a light beam incident obliquely with respect to the optical axis of the light-collecting optical system. 21. The coupling lens for an optical pickup device according to claim 19, wherein the light is emitted in a direction substantially parallel to the optical axis. 22. The coupling lens has diffraction patterns on both surfaces, chromatic aberration is corrected by a diffraction effect of the diffraction patterns on both surfaces, and the coupling lens is incident obliquely with respect to the optical axis of the condensing optical system. The coupling lens for an optical pickup device according to claim 20, wherein the principal ray of the light beam is emitted in a direction substantially parallel to the optical axis. 23. The coupling lens has a diffraction pattern on both surfaces, chromatic aberration is corrected by the diffraction effect of the diffraction pattern on one surface, and the light is condensed by the diffraction effect of the diffraction pattern on the other surface. 21. The cup for an optical pickup device according to claim 20, wherein a principal ray of a light beam incident obliquely with respect to the optical axis of the optical system is emitted in a direction substantially parallel to the optical axis. Ring lens. 24. A coupling lens for converting a divergence state of a light beam from a first light source having a wavelength λ1 and a second light source having a wavelength λ2, and a recording surface of an optical information recording medium, the light beam having the divergence state being converted. A light collecting optical system including an objective lens for collecting light, and a detector for detecting reflected light and / or transmitted light from the recording surface; In a coupling lens for an optical pickup device for information recording and reproduction capable of recording and / or reproducing information on a second optical information recording medium, the first light source and the second light source are unitized. Wherein the coupling lens is formed on at least one surface with a diffraction pattern for correcting chromatic aberration between a light beam from the light source having the wavelength λ1 and a light beam from the light source having the wavelength λ2. ,Previous Among the light beams emitted from the first light source or the second light source, an off-axis coma aberration of the light beam incident obliquely with respect to the optical axis of the light collecting optical system in the light collecting optical system is corrected. A coupling lens for an optical pickup device having off-axis characteristics. 25. The wavelength λ1 and the wavelength λ2 are λ1
<Λ2, where t1 is the thickness of the transparent substrate of the first optical information recording medium and t2 is the thickness of the transparent substrate of the second optical information recording medium. The coupling lens according to any one of claims 15 to 24, wherein the following relationship is established. 26. A light beam emitted from the second light source,
26. The coupling lens for an optical pickup device according to claim 25, wherein the light is incident obliquely with respect to the optical axis of the condensing optical system. 27. A coupling lens for an optical pickup device according to claim 15, wherein said coupling lens is a collimator for converting an incident divergent light beam into a light beam substantially parallel to an optical axis. . 28. A coupling lens for converting a divergent state of a light beam, wherein a principal ray of the light beam incident obliquely with respect to the optical axis of the coupling lens is directed in a direction substantially parallel to the optical axis of the coupling lens. A coupling lens that emits light. 29. The coupling lens according to claim 28, wherein the coupling lens has a diffraction pattern formed on at least one surface. 30. A coupling lens for converting a divergence state of a light beam, wherein a diffraction pattern for correcting chromatic aberration in a light beam from a light source having at least two different wavelengths is formed on at least one surface,
A cup which emits a principal ray of a light beam incident obliquely with respect to the optical axis of the coupling lens among the light beams of the three wavelengths in a direction substantially parallel to the optical axis of the coupling lens. Ring lens. 31. The coupling lens according to claim 30, wherein the coupling lens is a single lens. 32. The coupling lens has a diffraction pattern on only one surface, and furthermore, due to the diffraction effect of the diffraction pattern, further reduces a principal ray of a light beam incident obliquely with respect to the optical axis of the coupling lens. The coupling lens according to claim 30, wherein the light is emitted in a direction substantially parallel to an optical axis of the coupling lens. 33. The coupling lens has a diffraction pattern on both surfaces, and the coupling lens has a diffraction pattern on both surfaces.
The chromatic aberration is corrected, and the principal ray of the light beam incident obliquely with respect to the optical axis of the coupling lens is emitted in a direction substantially parallel to the optical axis of the coupling lens due to the diffraction effect of the diffraction patterns on both surfaces. The coupling lens according to claim 31, wherein the coupling lens is used. 34. The coupling lens has diffraction patterns on both surfaces, chromatic aberration is corrected by the diffraction effect of the diffraction pattern on one surface, and the coupling lens is corrected by the diffraction effect of the diffraction pattern on the other surface. 32. The coupling lens according to claim 31, wherein a principal ray of the light beam obliquely incident on the optical axis of the lens is emitted in a direction substantially parallel to the optical axis of the coupling lens.