JPH09326132A - Optical pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical pickup device capable of recording/reproducing an information signal on plural kinds of optical disks with different thickness of transparent substrates. SOLUTION: A luminous flux emitted from a light source 2 is made incident on an objective lens 4 through an aperture optical element 11 that one side surface is made an aperture diaphragm surface whose peripheral part is made a tapered surface 12 and the other side surface is made an aberration corrective surface (aspherical surface). The numerical aperture(NA) of the objective lens 4 is changed by moving and operating the aperture optical element 11 in the optical axial direction according to the thickness of the transparent substrates of the optical disks 6a, 6b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of an optical pickup device for writing and reading information signals on an optical recording medium such as an optical disk.

[0002]

2. Description of the Related Art Conventionally, optical recording media such as optical disks and optical cards have been proposed as recording media for information signals.
An optical pickup device for writing and reading information signals to and from such an optical recording medium has been proposed.

Such an optical recording medium has a transparent substrate made of a transparent material such as polycarbonate and a signal recording layer formed on one main surface of the transparent substrate.

The above optical pickup device includes a semiconductor laser as a light source, a beam splitter into which a light beam emitted from this semiconductor laser is incident, an objective lens into which the light beam passing through this beam splitter is incident, and a photodetector. Have The beam splitter is disposed such that the reflection surface has a 45 ° inclination with respect to the optical axis of the light beam from the semiconductor laser.

[0005] The light beam incident on the objective lens is condensed and irradiated on the signal recording surface of the optical recording medium by the objective lens. At this time, this luminous flux is
The optical recording medium is irradiated with light from the transparent substrate side of the optical recording medium, passes through the transparent substrate, and is focused on the signal recording surface, which is the surface of the signal recording layer. The objective lens is always supported by a biaxial actuator and operated to move so that the light beam is always focused on a portion (recording track) where the information signal is recorded on the signal recording surface.

In the optical recording medium, a light beam having passed through the objective lens is condensed and irradiated, so that an information signal is recorded at a position irradiated with the light beam.

[0007] The light beam radiated on the signal recording surface has a light amount, a light amount, in accordance with an information signal recorded on the signal recording surface.
Alternatively, the polarization direction is modulated, reflected by the signal recording surface, and returned to the objective lens.

[0008] The light beam reflected by the signal recording surface passes through the objective lens and reaches the beam splitter. The reflected light beam is branched by the beam splitter into a path returning to the semiconductor laser, and travels toward the photodetector.

The photodetector is a light receiving element such as a photodiode, and receives the light beam having passed through the beam splitter and converts the light beam into an electric signal. The information signal recorded on the optical recording medium is reproduced based on the electric signal output from the photodetector.

[0010]

By the way, in an optical recording medium such as an optical disc as described above, an information signal is recorded for use as an auxiliary storage device for a computer and as a recording medium for audio and image signals. Higher density is being promoted.

In order to record and reproduce information signals on an optical recording medium having a high recording density,
It is necessary that the objective lens has a larger numerical aperture (NA) and the beam spot formed by condensing the light beam on the optical recording medium is smaller.

However, when the numerical aperture of the objective lens increases, the inclination of the optical recording medium, the thickness unevenness of the transparent substrate of the optical recording medium, and the defocus (defocus) of the light beam on the optical recording medium. And the recording and reproduction of the information signal on the optical recording medium becomes difficult.

For example, when an inclination (skew) of the optical recording medium with respect to the optical axis of the objective lens occurs, a wavefront aberration occurs in a light beam condensed on the signal recording surface,
The electric signal (RF output) output from the photodetector is affected.

The wavefront aberration is dominated by tertiary coma which occurs in proportion to the cube of the numerical aperture of the objective lens and about the square of the tilt angle (skew angle) of the optical recording medium. Therefore, the permissible value for the tilt of the optical recording medium is inversely proportional to the cube of the numerical aperture of the objective lens, that is, it decreases as the numerical aperture increases.

Thickness 1.2 mm, diameter 80 mm or 12
An optical disk (such as a so-called “compact disk”), which has a transparent substrate formed of a 0 mm disk-shaped polycarbonate and is widely used at present, has a tilt angle of ± 0.5 ° or more. A tilt of ± 1 ° may occur.

In such an optical disk, the above-described wavefront aberration occurs in the light beam irradiated on the optical disk, the beam spot on the optical disk has an asymmetric shape, and intersymbol interference occurs remarkably, so that accurate signal reproduction is performed. Becomes difficult.

The amount of such third-order coma is proportional to the thickness of the transparent substrate of the optical disk. Therefore, by reducing the thickness of the transparent substrate (for example, to 0.6 mm), third-order coma can be reduced by half. When the coma aberration is to be reduced in this way, as the optical disk, a transparent substrate having a thickness of 1.2 mm and a transparent substrate having a thickness of 0.6 mm are used in combination. The Rukoto.

When a plane-parallel plate having a thickness of t is inserted into the optical path of the convergent light beam converged by the objective lens, t is related to the thickness t and the numerical aperture NA of the objective lens. × (NA) Spherical aberration proportional to ⁴ occurs.

The objective lens is designed so that the spherical aberration is corrected. That is, since the amount of spherical aberration that occurs when the thickness of the transparent substrate varies, the objective lens is designed to be adapted to the predetermined thickness of the transparent substrate.

An optical disk having a transparent substrate having a thickness of 1.2 mm (for example, a "compact disk") is formed by using an objective lens designed and adapted to an optical disk having a transparent substrate having a thickness of 0.6 mm. When recording and reproducing information signals to and from a write-once optical disk and a magneto-optical disk, the difference in the thickness of these transparent substrates (0.6 mm) is due to the transparency that the optical pickup device can handle. This greatly exceeds the allowable range of the error in the thickness of the substrate. In this case, the objective lens cannot correct the spherical aberration generated due to the difference in the thickness of the transparent substrate, and cannot record and reproduce information signals satisfactorily.

Here, it is conceivable to change the numerical aperture of the objective lens according to the thickness of the transparent substrate of the optical recording medium by using a mechanical diaphragm. However, providing a mechanical diaphragm causes the configuration and the size of the optical pickup device to be complicated and large.

Accordingly, the present invention has been proposed in view of the above situation, and has been proposed for an optical recording medium having different thicknesses of transparent substrates without complicating the device configuration and increasing its size. Another object of the present invention is to solve the problem of providing an optical pickup device capable of satisfactorily recording and reproducing information signals.

[0023]

In order to solve the above-mentioned problems, an optical pickup device according to the present invention comprises a light source and an objective for converging a light beam emitted from the light source on a signal recording surface of an optical recording medium. A lens, a light detecting means for detecting the reflected light of the light flux from the signal recording surface, and a surface disposed on the diverging optical path between the light source and the objective lens, one surface being an aperture stop surface and the other being It is provided with an aperture optical element whose surface is a light transmitting surface over the entire surface, and a moving operation means for operating the aperture optical element in the optical axis direction of the light flux.

Further, according to the present invention, in the above optical pickup device, the aperture stop surface of the aperture optical element has a conical taper surface portion on the peripheral edge side, and an inner side portion surrounded by the taper surface portion is open. It is supposed to correspond to the section.

Further, according to the present invention, in the above optical pickup device, the aperture optical element is centered and positioned by supporting the tapered surface portion from the peripheral side.

In the optical pickup device of the present invention, the aperture stop surface of the aperture optical element has a light shielding processing portion on the peripheral side, and an inner portion surrounded by the light shielding processing portion has an opening portion. It is supposed to correspond to.

Further, according to the present invention, in the above optical pickup device, the peripheral edge side portion of the aperture stop surface of the aperture optical element is a curved surface portion, and the inner side portion surrounded by the curved surface portion corresponds to the opening portion. It was decided to do.

Further, according to the present invention, in the above optical pickup device, the light transmitting surface, which is the other surface of the aperture optical element, is an aspherical surface for correcting aberration occurring in the transparent substrate of the optical recording medium. I decided to stay.

Further, according to the present invention, in the above optical pickup device, a lateral movement operating means for moving the aperture optical element in a direction perpendicular to the optical axis of the light beam is provided.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, the optical pickup device according to the present invention is applied to an optical recording medium in which a transparent substrate has a thickness of 0.6 mm and a first optical disk which is an optical recording medium and a transparent substrate has a thickness of 1.2 mm. It is configured as an optical pickup device capable of recording and reproducing an information signal with respect to both the second optical disc which is a medium.

[1] Regarding First and Second Optical Discs The first optical disc is, as shown in FIGS. 1 to 3,
The transparent substrate is formed of a disc-shaped polycarbonate having a thickness D ₁ (0.6 mm) and a diameter of 120 mm, and a signal recording layer formed on one main surface of the transparent substrate. The first optical disc 6a is a disc body (so-called double-sided disc or multi-layer disc) having a thickness of 1.2 mm in which the two first optical discs 6a are bonded to each other on the signal recording layer sides. There is.

The wavelength of the first optical disk 6a is 63
A 5 nm laser light beam is used to record and reproduce information signals through an objective lens having a numerical aperture (NA) of 0.6.

The one that corresponds to such a first optical disk 6a is, for example, a so-called "SD", or
A "Digital Video Disc (DVD)" has been proposed.

The second optical disk 6b is shown in FIGS.
And as shown in FIG. 4, a transparent substrate formed of a disc-shaped polycarbonate having a thickness D ₂ (1.2 mm) and a diameter of 80 mm or 120 mm, and a signal recording layer formed on one main surface portion of the transparent substrate. And is configured.

The wavelength of the second optical disk 6b is 78
A 0 nm laser beam is used to record and reproduce information signals via an objective lens having a numerical aperture of 0.45.

For example, a so-called "compact disc (CD)" has been proposed as a device corresponding to the second optical disc 6b.

[2] Constitution of Optical Pickup Device The optical pickup device according to the present invention has a semiconductor laser 2 as a light source, as shown in FIG.
The semiconductor laser 2 emits a laser beam which is linearly polarized coherent light. This laser beam is a divergent beam. The wavelength of this laser beam is 635 nm.

The above laser beam passes through the aperture optical element 11 and reaches the beam splitter 3. As shown in FIGS. 5 and 6, the aperture optical element 11 has one surface serving as an aperture stop surface and the other surface serving as a light transmitting surface 7 over the entire surface, and injection molding using a synthetic resin material. It is formed by means or glass mold. The aperture stop surface of the aperture optical element 11 has a conical tapered surface portion 12 on the peripheral side portion, and an inner side portion surrounded by the tapered surface portion 12 corresponds to the circular opening portion 8. A circular boundary line 9 between the tapered surface portion 12 and the opening 8 corresponds to a diaphragm. The tapered surface portion 12 is formed so as to thicken the outer peripheral edge side of the aperture optical element 11. The light transmitting surface 7 is a flat surface. The light transmitting surface 7 is an incident surface of the laser light from the semiconductor laser 2 on the aperture optical element 11 and is perpendicular to the optical axis of the laser light.

The aperture optical element 11 is moved by a moving operation mechanism described later along the optical axis of the laser beam from the semiconductor laser 2 as shown by an arrow M in FIG. The movement operation is performed during the period 3.

The beam splitter 3 is formed in a flat plate shape, and its main surface portion is arranged with an inclination angle of 45 ° with respect to the optical axis of the laser beam from the semiconductor laser 2. The beam splitter 3 reflects the laser light flux from the semiconductor laser 2 by the main surface portion on the semiconductor laser 2 side and deflects it by 90 °.

The laser beam reflected by the beam splitter 3 is incident on the objective lens 4.

The aperture optical element 11 changes the ratio of the cross-sectional area of the light flux to be transmitted to the cross-sectional area of the laser light flux from the semiconductor laser 2 depending on the position between the semiconductor laser 2 and the beam splitter 3. .

That is, the above-mentioned aperture optical element 11 is shown in FIG.
As shown in FIG. 2, when the semiconductor laser 2 (or the integrated element 27 described later) is in the first position, the laser beam emitted from the semiconductor laser 2 is almost entirely emitted from the opening 8 when the laser beam is emitted. It is transmitted as Ra. Further, as shown in FIG. 4, the aperture optical element 11 includes the semiconductor laser 2 (or an integrated element 2 described later).
7) In the second position apart from 7), only the central portion of the laser beam emitted by the semiconductor laser 2 is transmitted through the opening 8 as the laser beam Rb. In the aperture optical element 11, the tapered surface portion 1
As shown in FIGS. 4 and 7, the light flux passing through 2 is refracted in a direction away from the optical axis of the laser light flux, and is deflected as a laser light flux Rc in a direction away from the laser light flux Rb.

The position of the aperture optical element 11 can be any position between the first position and the second position.

The laser light flux (laser light flux Ra or laser light flux R that has passed through the opening 8 of the aperture optical element 11 is described.
b) is incident on the objective lens 4. This objective lens 4
Are supported by a lens frame (not shown). The objective lens 4 focuses the laser beam emitted from the semiconductor laser 2 on the signal recording surface of each of the optical discs 6a and 6b. That is, the laser light flux incident on the objective lens 4 is condensed by the objective lens 4 onto the signal recording surface of each of the optical discs 6a and 6b and irradiated.

At this time, this laser beam is transmitted from the transparent substrate side of each of the optical discs 6a and 6b.
The a and 6b are irradiated, transmitted through the transparent substrate, and focused on the signal recording surface which is the surface portion of the signal recording layer. The objective lens 4 is supported by a biaxial actuator (not shown) via the lens frame, and is moved and operated in the optical axis direction and the direction orthogonal to the optical axis as shown by arrows F and T in FIG. As a result, the laser light flux is always focused on the portion (recording track) where the information signal is recorded on the signal recording surface.

The objective lens 4 has a numerical aperture (NA) of 0.6. The objective lens 4 has a spherical aberration generated in proportion to t × (NA) ⁴ when a plane parallel plate having a thickness t is inserted in the optical path of the convergent light beam condensed by the objective lens 4. Designed to be compensated. That is, the objective lens 4 is designed as an optical recording medium having a transparent substrate with a thickness of 0.6 mm.

In each of the above optical disks 6a and 6b,
By collecting and irradiating the laser light flux that has passed through the objective lens 4, an information signal is recorded at the position where the laser light flux is radiated.

Further, the laser light flux irradiated on the signal recording surface is modulated in the amount of light or the polarization direction according to the information signal recorded on the signal recording surface and is reflected by the signal recording surface. , And returns to the objective lens 4.

When the aperture optical element 11 is in the first position, as shown in FIG. 3, the semiconductor laser 2 is
Almost all of the laser light flux emitted by the laser light is transmitted through the opening 8 as a laser light flux Ra, and at this time, the numerical aperture (NA) of the objective lens 4 is 0.6.

Further, when the aperture optical element 11 is in the second position as shown in FIG. 4, only the central portion of the laser light flux emitted by the semiconductor laser 2 serves as the laser light flux Rb. 8 and the objective lens 4 has a numerical aperture of 0.37.

The position of the aperture optical element 11 is the same as that of the first optical element.
, And the second position, the numerical aperture of the objective lens 4 is such that the numerical aperture optical element 11 is in the first position (NA = 0.
From 6), the aperture optical element 11 can be changed steplessly over the state (NA = 0.37) in the second position.

The optical pickup device has a photodetector 5 which serves as a photodetecting means for detecting the reflected light beams of the laser light beams Ra and Rb from the signal recording surface.

That is, the reflected light beam reflected by the signal recording surface reaches the beam splitter 3 via the objective lens 4. This reflected light flux is transmitted through the beam splitter 3 and is branched to the path returning to the semiconductor laser 2 to the photodetector 5.

The photodetector 5 is a light receiving element such as a photodiode, receives the reflected light flux passing through the beam splitter 3, and converts it into an electric signal. This photo detector 5
The information signal recorded on each of the optical discs 6a and 6b is reproduced based on the electric signal output from the optical disc.

In this optical pickup device, when recording and reproducing an information signal on the first optical disk 6a, the aperture optical element 11 is set to the first position as shown in FIG. Substantially all of the laser light flux from the semiconductor laser 2 passes through the aperture 8 of the aperture optical element 11, and the numerical aperture of the objective lens 4 is 0.6.
Becomes

In this case, the first optical disk 6a
The original condition for recording and reproducing the information signal with respect to (1), that is, the condition that the numerical aperture of the objective lens 4 is 0.6 and the wavelength of the laser beam is 635 nm is satisfied, and is recorded on the first optical disc 6a. Sufficient spatial frequency characteristics (Modulation transfer function; MT) for all signals (3T to 11T (T is a channel bit))
F) is obtained, and good recording and reproduction are possible.

Further, in this optical pickup device, when recording and reproducing an information signal with respect to the second optical disk 6b, the aperture optical element 11 is set to the second position as shown in FIG. Only the central portion of the laser beam from the semiconductor laser 2 passes through the aperture 8 of the aperture optical element 11, and the substantial numerical aperture of the objective lens 4 becomes 0.37.

The numerical aperture of the objective lens 4 at this time is the original condition for recording and reproducing the information signal with respect to the second optical disc 6b, that is, the numerical aperture of the objective lens 4 is 0.45 and the laser light flux is Is 0.45 × (635/780) so that a beam spot having a diameter substantially the same as the beam spot diameter on the signal recording surface of the laser light flux under the condition that the wavelength is 780 nm is obtained. It is about 37.

At this time, the spherical aberration generated in relation to the thickness t of the transparent substrate and the numerical aperture (NA) of the objective lens 4, that is, in proportion to t × (NA) ⁴ , is Since the numerical aperture is small, it can be suppressed, and good recording and reproduction on the second optical disc 6b can be realized. That is, in this case, the second optical disc 6
Sufficient spatial frequency characteristics (Modulation transfer function; MTF) are obtained for all signals (3T to 11T (T is a channel bit)) recorded in b,
Good recording and reproduction is possible.

In this optical pickup device, the numerical aperture of the objective lens 4 is selected when it is known which one of the first and second optical disks 6a and 6b is mounted. This can be done by moving the aperture optical element 11 according to the type of optical disc.

The first and second optical disks 6 are also provided.
When either a or 6b is mounted, the numerical aperture of the objective lens 4 is set to 0.3, the signal of the optical disk mounted in this state is read, and the mounted optical disk is determined from the contents of this signal. It may be possible to determine which of the first and second optical disks 6a and 6b it is. That is, the numerical aperture of the objective lens 4 is 0.
Even in the state of No. 3, some of the signals recorded on the first optical disc 6a can be read, so that the loaded optical disc is the first optical disc 6a based on the read signal. It can be determined.

This optical pickup device is a recording / reproducing device constructed by using this optical pickup device, as shown in FIG.
The objective lens 4 is disposed so as to face the signal recording surface of the optical discs 6a and 6b which is rotated by 8, and the optical discs 6a and 6b are moved over the inner and outer peripheries thereof.
The optical pickup device can write and read information signals over the entire signal recording surfaces of the optical discs 6a and 6b.

A disc-shaped disk table 19 is attached to the drive shaft of the spindle motor 18. The optical discs 6a and 6b are held at their central portions by the disc table 19 and rotated by the spindle motor 18.

[3] Configuration of Optical Pickup Device Using Integrated Element Then, the optical pickup device according to the present invention may be configured by using an integrated device (so-called laser coupler) 27 as shown in FIG. Good. The integrated device 27 is configured by forming a semiconductor laser (laser chip) 22 serving as a light source and a plurality of photodetection units 25 and 26 on a silicon transparent substrate 21. Then, the plurality of light detection units 25, 2
A beam splitter prism 23 is arranged on the surface 6.

In this integrated device 27, the laser beam emitted from the semiconductor laser 22 is reflected by the inclined surface portion 24 having an inclination of 45 °, which is one end portion of the beam splitter prism 23, and is directed to the silicon transparent substrate 21. It is fired vertically. The laser light flux emitted from the integrated element 27 in this manner is the aperture optical element 1 described above.
After passing through 1, the light enters the objective lens 4.

The laser light beam focused on the signal recording surface of each of the optical disks 6a and 6b by the objective lens 4 is reflected by the signal recording surface, passes through the objective lens 4 and the aperture optical element 11, and Returning to the slope portion 24. The reflected light flux returned to the slope portion 24 is the slope portion 2
The light enters the beam splitter prism 23 while being refracted at 4. This beam splitter prism 2
The light flux incident on the inside of 3 is applied to each of the photodetectors 25 and 26. Each of the photodetectors 25 and 26 outputs an electric signal according to the irradiated luminous flux.

[4] Constitution of Optical Pickup Device Using Collimator Lens In the above-described embodiment of the optical pickup device according to the present invention, a laser light beam which is a divergent light beam (diffused light beam) from the semiconductor lasers 2 and 22 is used. Adopts a so-called finite optical system which is incident on the objective lens 4. However, the optical pickup device according to the present invention is not limited to the one that employs such a finite optical system, and FIGS.
As shown in FIG. 9, a so-called infinite optical system may be adopted in which a laser light beam, which is a divergent light beam from the semiconductor lasers 2 and 22, is incident on the objective lens 4 as a parallel light beam by the collimator lens 10.

When an infinite optical system is adopted in this optical pickup device, the semiconductor laser 2,
The laser light beams Ra and Rb, which are divergent light beams emitted from the light emitting point 2a of 22, are incident on the collimator lens 10 after passing through the aperture optical element 11. The laser beam R
The light beams a and Rb are made into parallel light beams by passing through the collimator lens 10. The laser light beams Ra and Rb thus formed into parallel light beams are incident on the objective lens 4 via the beam splitter 3, the deflection mirror 13, or directly.
The objective lens 4 in this case is designed to focus the incident parallel light flux on the signal recording layers of the optical discs 6a and 6b.

[5] Another Example of Shape of Aperture Optical Element In this optical pickup device, as shown in FIG. 8, in the aperture optical element 11, the tapered surface portion 12 causes the aperture optical element 11 to open the aperture optical element 11. The optical element 11 may be formed as a tapered surface that becomes thinner toward the outer peripheral edge side. In this case, the laser light flux Rc that has passed through the tapered surface portion 12 is deflected in a direction approaching the optical axis of the laser light flux Rb that has passed through the opening portion 8 and is incident on the objective lens 4. However, it is not condensed on the signal recording surfaces of the optical discs 6a and 6b. Therefore, also in this case, the aperture optical element 11
The effective numerical aperture of the objective lens 4 can be varied by moving the lens along the optical axis of the laser beam from the semiconductor laser 2.

As described above, when the tapered surface portion 12 is formed into a tapered surface such that the aperture optical element 11 becomes thinner toward the outer peripheral edge side of the aperture optical element 11, the aperture optical element 11 is closer to the peripheral side than the peripheral side. By supporting the tapered surface portion 12, it is possible to perform alignment and position.

Further, in this optical pickup device, the aperture optical element 11 has the entire surface of the light transmitting surface 7 as shown in FIG. 9 when the optical system of the optical pickup device requires aberration correction. May be formed as the aberration correction surface 7a which is an aspherical surface for performing aberration correction.

In this way, when the light transmitting surface 7 is formed as the aberration correcting surface 7a, the aperture optical element 1 is
When 1 is brought close to the semiconductor lasers 2 and 22,
The laser light flux from the semiconductor lasers 2 and 22 can be transmitted through only the narrow central portion of the aberration correction surface 7a. In this case, the aberration correction surface 7a is approximate to a flat surface for the laser light flux, and the laser light flux is less affected by the wavefront due to transmission through the aberration correction surface 7a. Then, in the case where the light transmitting surface 7 is the aberration correcting surface 7a, when the aperture optical element 11 is separated from the semiconductor lasers 2 and 22, the laser light flux from the semiconductor lasers 2 and 22 is The entire surface of the aberration correction surface 7a is transmitted. In this case, the laser light flux is greatly affected by the wave front by passing through the aberration correction surface 7a, and the aberration is corrected.

That is, in this optical pickup device, the occurrence of aberration is small when the aperture optical element 11 is in the first position (that is, when the numerical aperture of the objective lens 4 is 0.6). If the optical elements such as the objective lens 4 are designed so that when the aperture optical element 11 reaches the second position (that is, the numerical aperture of the objective lens 4 becomes 0.37). The aberration that occurs when the above) can be corrected by the aberration correction surface 7a.

Further, in the case where the light transmitting surface 7 is the aberration correcting surface 7a, the change of the inclination of the signal recording surface of the optical discs 6a and 6b with respect to the optical axis of the objective lens 4 is made to follow the changes shown in FIGS. As indicated by an arrow N in FIG. 2, by operating the aperture optical element 11 in a direction orthogonal to the optical axis of the laser beam from the semiconductor laser 2 by a lateral movement operating means (not shown), so-called disc skew occurs. A servo mechanism that corrects the generated coma aberration can be configured. The lateral movement operation means uses the driving force from a driving source such as a motor in accordance with the inclination of the signal recording surface of the optical discs 6a and 6b with respect to the optical axis of the objective lens 4 detected by a skew sensor to open the aperture optical system. It is configured to move the element 11.

Further, in this optical pickup device, the aperture optical element 11 has the light transmitting surface 7 as shown in FIG. 10 when the optical pickup device requires aberration correction and focus position correction. The aberration correction surface 7b may be formed as an aspherical surface for correcting the aberration and having power (degree).

Also in this case, in this optical pickup device, when the aperture optical element 11 is at the first position (that is, the numerical aperture of the objective lens 4 is 0.
If the optical elements such as the objective lens 4 are designed so that the aberration and the focus movement are reduced when the aperture optical element 11 reaches the second position (that is, The aberration and the focus movement that occur when the numerical aperture of the objective lens 4 becomes 0.37) can be corrected by the aberration correction surface 7b.

Further, in this optical pickup device, as shown in FIG. 11, in the aperture optical element 11, a peripheral portion of the aperture stop surface serves as a light shielding processing portion 12a and is surrounded by the light shielding processing portion 12a. The inner side portion may be formed as the opening 8. As the light-shielding treatment performed on the light-shielding processing unit 12a, so-called satin treatment (sanding treatment) can be used. In this case, the laser light flux incident on the light shielding processing section 12a is diffusely reflected and diffused, and is hardly incident on the objective lens 4.

Further, in this optical pickup device, as shown in FIG. 12, in the aperture optical element 11, the inner side portion surrounded by the tapered surface portion 12 is an elliptical (oval) opening portion 8. It may be formed by.

In this case, an elliptical opening is formed by moving the aperture optical element 11 in a direction away from the semiconductor laser 2, and on the signal recording surface, on the signal recording surface. Optical disc 6
It is possible to form beam spots having different diameters in the radial direction of a and 6b (direction along the recording track) and the tangential direction (direction orthogonal to the recording track). For example, in this case, the beam spot diameter in the radial direction is formed by an objective lens having a numerical aperture of 0.37, and the beam spot diameter in the tangential direction has a numerical aperture of about 0.2 to 0.
It can be formed by about 5 objective lenses.

In this optical pickup device, as shown in FIG. 13, the aperture optical element 11 has a curved surface portion (toric surface portion) at the peripheral edge portion of the aperture stop surface.
12b, and the inner side portion surrounded by the curved surface portion 12b may be formed as the opening 8.
In this case, the laser light flux incident on the curved surface portion 12b is converged or diffused in the vicinity of the aperture optical element 11, and is hardly incident on the objective lens 4. It

In this optical pickup device, the aperture optical element 11 may be used also as an optical element for correcting astigmatism and coma by tilting it with respect to the optical axis of the objective lens 4. .

Further, in the above-described embodiment, the aperture optical element 11 receives the laser beam from the semiconductor laser 2 from the light transmitting surface 7 side and emits the laser beam from the aperture stop surface. However, in the optical pickup device according to the present invention, conversely, in the aperture optical element 11, the laser light flux from the semiconductor laser 2 is incident from the aperture stop surface side and the laser light flux is emitted from the light transmitting surface 7. It may be ejected.

Further, in this optical pickup device, the optical disc 6 is emitted from the objective lens 4.
The return light from the optical discs 6a and 6b of the light fluxes radiated on the a and 6b is transferred to the tapered surface portion 12 of the aperture optical element 11.
It may be detected through.

In this optical pickup device, the laser power Rc transmitted through the taper portion 12 can be used to execute the automatic power control (APC) of the semiconductor laser 2. That is, the light amount of the laser beam Rc that has passed through the tapered portion 12 and is off the optical path toward the objective lens 4 is detected by the light receiving element, and the light emission output of the semiconductor laser 2 is controlled based on the detection result. It is possible to realize automatic power control (APC) for keeping the light emission output of the semiconductor laser 2 constant.

[6] Constitution of Moving Operation Mechanism In the optical pickup device according to the present invention, a moving operation mechanism for moving the aperture optical element 11 between the first position and the second position. As shown in FIG.
As shown in FIG. 3, it is conceivable that a substantially rod-shaped contact rod 15 is attached to a support frame that supports the aperture optical element 11, and the contact rod 15 is extended to the outer side of the optical pickup device. .

That is, in this moving operation mechanism,
The contact rod 15 is connected to the aperture optical element 11 at the central portion, and both ends of the contact rod 15 are connected to the optical disc 6a,
It is directed to the outer peripheral side and the inner side of 6b. In this optical pickup device, the optical path from the semiconductor laser 2 to the collimator lens 10 (or the objective lens 4) is set in the radial direction of the optical discs 6a and 6b (direction from the outer peripheral side toward the inner peripheral side). There is. An inner peripheral contact block 17 is fixedly provided on the inner peripheral sides of the optical disks 6a and 6b, that is, in the vicinity of the spindle motor 18, facing one end of the contact rod 15. There is. An outer peripheral contact block 16 is fixedly provided on the outer peripheral sides of the optical disks 6a and 6b so as to face the other end of the contact rod 15.

When the optical pickup device is moved further toward the inner peripheral side of the optical discs 6a, 6b than the position corresponding to the innermost peripheral position of the optical discs 6a, 6b, one end of the contact rod 15 is moved. Comes into contact with the inner peripheral side contact block 17, and the contact rod 15 is moved and operated with respect to the optical pickup device to bring the aperture optical element 11 to the first position. When the optical pickup device is moved further toward the outer peripheral side of the optical discs 6a, 6b than the position corresponding to the outermost peripheral position of the optical discs 6a, 6b, the other end of the contact rod 15 is moved to the above-mentioned position. The contact rod 15 contacts the outer peripheral contact block 16, and the contact rod 15
The aperture optical element 11 is moved to the second position by moving the optical pickup device.

In this case, the position of the aperture optical element 11 is set to the first position or the second position by controlling the position of the optical pickup device with respect to the contact blocks 16 and 17. It can be any position in between.

Further, a rotary lever 34 rotatably supported via a support shaft 33 is provided for a fixed portion at a position corresponding to substantially the central portion of the contact rod 15. By connecting 34 to the corresponding connecting rod 15 and attaching the tension coil spring 32 to the rotating lever 34, the corresponding connecting rod 15 does not stop at a position midway between the first position and the second position. You can

That is, a linking pin 35 is provided on the tip end side of the rotating lever 34, and the linking pin 35 is provided.
Is linked to a linking claw 36 provided on the contact rod 15. When the contact rod 15 is operated to move between the first position and the second position, the rotation lever 34
Is rotated about 180 °. The tension coil spring 32 is located at a position further distant from the center of an approximately semicircular arc drawn by the linking pin 35 and a movement locus of the linking pin 35 associated with the turning of the turning lever 34. It is stretched between a hooking pin 31 provided and is extended most when the turning lever 34 reaches the center of the turning range.

That is, the tension coil spring 32 is
As shown by an arrow C in FIG. 14, by pulling the linkage pin 35 toward the latch pin 31 side, the rotation lever 34 is moved to one side of the center of the rotation range of the rotation lever 34. When the rotation lever 34 is on the other side of the center of the rotation range of the rotation lever 34, the rotation lever 34 is urged to rotate on the other side.

Therefore, when the aperture optical element 11 is located closer to the first position than the central position between the first position and the second position, it is moved to the first position side. When it is biased and is located closer to the second position than the central position between the first position and the second position, it is biased to move toward the second position.

As shown in FIG. 15, the moving operation mechanism may be constructed by combining an electromagnetic drive mechanism such as a so-called plunger and a biasing spring 29. The plunger has a coil 30 and an iron core 31. In this plunger, when a drive current is supplied to the coil 30, the iron core 31
As shown by the arrow B in FIG. 15, it is urged in one direction and moved. The iron core 31 is attached to a support frame that supports the aperture optical element 11. Then, the biasing spring 29 biases the iron core 31 in a direction opposite to the biasing direction when a drive current is supplied to the coil 30, as shown by an arrow A in FIG. There is. And
The direction in which the iron core 31 is biased when a drive current is supplied to the coil 30 and the biasing direction by the biasing spring 29 are the optical axis of the laser light flux from the semiconductor laser 2 in the optical pickup device. The direction is made.

In the optical pickup device having this movement operation mechanism, when no drive current is supplied to the coil 30, the aperture optical element 11 is moved to the first position by the urging force of the urging spring 29. (Or the second position described above). Then, in this optical pickup device, when a drive current is supplied to the coil 30, the aperture optical element 11 is moved to the second position (or the first position) by the urging force of the plunger. Positioned.

Further, as shown in FIG. 16, the moving operation mechanism is provided with an annular cam groove 37 on the optical pickup device, and a copying pin on the moving block 39 connected to the aperture optical element 11. 41 may be provided, and the mechanism for positioning the aperture optical element 11 at the first position or the second position by moving the copying pin 41 following the cam groove 37.

That is, as shown in FIG. 16 and FIG. 17, the cam groove 37 is a cam groove formed in a substantially oval shape, and one end side of the oval shape in the major axis direction is the aperture optical. It corresponds to the first position of the element 11, and the other end side corresponds to the second position of the aperture optical element 11. On the other end side of the cam groove 37, as shown in FIGS. 17 and 18, a trap portion 44 bent toward the inner side of the ellipse formed by the cam groove 37 is provided. Also, this cam groove 3
The bottom surface of 7 has a pair of step portions 42 having the same directivity with respect to one direction of rotation along the cam groove 37.
43 are provided. These step portions 42 and 43 are located in front of one end portion of the cam groove 37 and in the trap portion 4 with respect to one direction of rotation along the cam groove 37.
It is provided in front of 4.

The copying pin 41 provided on the moving block 39 is movably supported in the support groove 40 provided on the moving block 39, and the cam groove 37 is supported with respect to the moving block 39. It is possible to move by a distance corresponding to the short diameter of an oval made by. That is, the moving block 39 causes the aperture optical element 11 to move.
Is moved to the first position and the aperture optical element 11 is moved to the second position, the copying pin 41 moves the moving block 39 in the support groove 40. By being moved relative to the cam groove 37, the cam groove 37 can be moved following the cam groove 37. The copying pin 41 is pressed against the bottom surface of the cam groove 37 by a biasing spring 45, as shown by an arrow P in FIG. Therefore, as shown by F in FIG. 16, the copying pin 41 is located in the one end side portion of the cam groove 37 (when the aperture optical element 11 is in the first position), the moving block. When 39 is moved toward the other end side of the cam groove 37, it is blocked by the step portion 42, so that FIG. 16 and FIG.
As indicated by the middle arrow J, the cam groove 37 can be moved in only one direction.

When the moving block 39 reaches the other end portion of the cam groove 37, the copying pin 41 is used.
Moves along the cam groove 37 as shown by an arrow J in FIGS. Then, the moving block 3
When 9 reaches the other end side of the cam groove 37, as shown by H in FIG.
When the movable block 39 reaches the other end of the cam groove 37 and then slightly returns to the one end side of the cam groove 37, the copying pin 41 is indicated by an arrow Q in FIG. 18 as indicated by G in FIG. As shown, the trap portion 44 passes through the step portion 43.
Reach inside. At this time, the aperture optical element 11 is in the second position.

Next, when the moving block 39 moves again toward the other end side of the cam groove 37, the copying pin 41 is moved.
Is restricted in the moving direction by the stepped portion 43, as shown in FIG.
8 As indicated by a middle arrow K, the head moves along the cam groove 37 in a direction away from the step 43. When the moving block 39 reaches the most other end side of the cam groove 37, as shown by H in FIG.
1 also reaches the other end of the cam groove 37, and when the moving block 39 returns to the one end side direction of the cam groove 37,
As shown by the arrow K in FIGS. 16 and 17, the copying pin 4
1 moves in the one end side direction of the cam groove 37 along the cam groove 37. When the moving block 39 reaches the one end side portion of the cam groove 37, the copying pin 41 is formed.
16 reaches the one end side portion of the cam groove 37 as indicated by F in FIG.

The moving block 39 is urged to move toward the one end side of the cam groove 37 by the tension coil spring 38, as shown by an arrow E in FIG. Therefore, when the aperture optical element 11 is in the first position, the moving block 39 resists the biasing force of the tension coil spring 38 and the copying pin 41 is indicated by H in FIG. When the moving operation for the moving block 39 is released, the copying pin 41 is stopped at the trap portion 44, and the aperture optical element 11 is moved to the second end side. Stop at position. Then, when the aperture optical element 11 is in the second position, the moving block 39 resists the biasing force of the tension coil spring 38, and the copying pin 41 shows the cam groove 37 shown by H in FIG. When the moving operation for the moving block 39 is released, the copying pin 41 moves to the one end side portion of the cam groove 37 and stops, and the opening is stopped. The optical element 11 is stopped at the first position.

That is, in this moving operation mechanism,
Regardless of whether the aperture optical element 11 is in the first position or the second position, the moving block 39 extends until the copying pin 41 reaches the most other end side portion of the cam groove 37 shown by H in FIG. Is moved against the biasing force of the tension coil spring 38, so that the aperture optical element 1
1 can be moved to the first position or the second position.

The moving block 39 is moved against the biasing force of the tension coil spring 38 to move the copying pin 4
The operation of bringing 1 to the most other end side portion of the cam groove 37 is performed by the optical disc 6a of the optical pickup device,
It can be made to interlock with the movement of the inner and outer circumferences of 6b. For example, when the optical pickup device is moved further toward the outer peripheral side of the optical discs 6a and 6b than the position corresponding to the outermost peripheral positions of the optical discs 6a and 6b, a part of the moving block 39 is fixed. The movable block 39 can be configured to be moved to a predetermined position with respect to the optical pickup device by abutting on a block arranged as a unit.

[0105]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The objective lens 4 is formed from a light emitting point 2a of a semiconductor laser 2 which is a main part of an optical pickup device according to the present invention.
We designed the optical system up to. That is, as shown in FIG. 19, the focal length fc of the collimator lens 10 is set to 25.5504 mm, and the light emitting point 2 is set.
When the distance from a to the incident surface (light transmitting surface 7) of the aperture optical element 11 at the first position (Position 1) is L ₁ , the numerical aperture (NA) of the objective lens 4 at this time is 0.6. And Further, the distance from the light emitting point 2a to the incident surface (light transmitting surface 7) of the aperture optical element 11 at the second position (Position 2) is L ₂ , and the numerical aperture (NA) of the objective lens 4 at this time is NA. ) Is 0.37. Under this condition, the following 6 designs and aberrations were calculated.

(1) L ₁ = 5 mm, L ₂ = 10 mm (however, numerical aperture is only 0.37) (2) L ₁ = 5 mm, L ₂ = 10 mm (3) L ₁ = 4 mm , L ₂ = 10 mm (4) L ₁ = 3 mm, L ₂ = 10 mm (5) L ₁ = 1 mm, L ₂ = 10 mm (6) L ₁ = 1 mm, L ₂ = 3 mm As shown in the following [Table 1], the axial wavefront aberration (λ _RMS value) for each of these is 0.002 in (1).
To 0.070, (2) 0.012 to 0.010,
0.003 to 0.007 in (3), 0.00 in (4)
2 to 0.004, 0.002 to 0.00 in (5)
0 and (6) were 0.003 to 0.005.

[0107]

[Table 1]

Specific examples (design examples) of the above (1) to (6) will be shown below. The refractive index of the glass material used in this example is as shown in [Table 2] below.

[0109]

[Table 2]

(1) When L ₁ = 5 mm and L ₂ = 10 mm (however, the numerical aperture is only 0.37) In this case, when the aperture optical element 11 is at the first position (Position 1). As shown in FIGS. 20, 21, and 25, L ₁ is 5 mm, and the numerical aperture (NA) of the objective lens 4 is 0.37. Also,
The aperture optical element 11 has the second position (Position 2).
26, 27 and 29, L ₂ is 10 mm, and the numerical aperture (NA) of the objective lens 4 is 0.37. The lens data in this case are as shown in [Table 3] to [Table 5] below.

[0111]

[Table 3]

[0112]

[Table 4]

[0113]

[Table 5]

(2) When L ₁ = 5 mm and L ₂ = 10 mm In this case, when the aperture optical element 11 is at the first position (Position 1), as shown in FIG.
L ₁ is 5 mm, and the numerical aperture (NA) of the objective lens 4 is 0.6. In addition, the aperture optical element 11
2 is in the second position (Position 2), as shown in FIG.
As shown in FIG. 7, L ₂ is 10 mm, and the numerical aperture (NA) of the objective lens 4 is 0.37. The lens data in this case is as shown in the following [Table 6] to [Table 8].

[0115]

[Table 6]

[0116]

[Table 7]

[0117]

[Table 8]

(3) When L ₁ = 4 mm and L ₂ = 10 mm In this case, when the aperture optical element 11 is at the first position (Position 1), as shown in FIG.
L ₁ is 4 mm, and the numerical aperture (NA) of the objective lens 4 is 0.6. In addition, the aperture optical element 11
2 is in the second position (Position 2), as shown in FIG.
As shown in FIG. 7, L ₂ is 10 mm, and the numerical aperture (NA) of the objective lens 4 is 0.37. The lens data in this case is as shown in the following [Table 9] to [Table 11].

[0119]

[Table 9]

[0120]

[Table 10]

[0121]

[Table 11]

(4) When L ₁ = 3 mm and L ₂ = 10 mm In this case, when the aperture optical element 11 is at the first position (Position 1), as shown in FIG.
L ₁ is 3 mm, and the numerical aperture (NA) of the objective lens 4 is 0.6. In addition, the aperture optical element 11
2 is in the second position (Position 2), as shown in FIG.
As shown in FIG. 7, L ₂ is 10 mm, and the numerical aperture (NA) of the objective lens 4 is 0.37. The lens data in this case is as follows [Table 12] to [Table 14]
As shown in.

[0123]

[Table 12]

[0124]

[Table 13]

[0125]

[Table 14]

(5) L ₁ = 1 mm and L ₂ = 10 mm In this case, when the aperture optical element 11 is at the first position (Position 1), as shown in FIG.
L ₁ is 1 mm, and the numerical aperture (NA) of the objective lens 4 is 0.6. In addition, the aperture optical element 11
2 is in the second position (Position 2), as shown in FIG.
As shown in FIG. 7, L ₂ is 10 mm, and the numerical aperture (NA) of the objective lens 4 is 0.37. The lens data in this case are as follows [Table 15] to [Table 17]
As shown in.

[0127]

[Table 15]

[0128]

[Table 16]

[0129]

[Table 17]

(6) When L ₁ = 1 mm and L ₂ = 3 mm In this case, when the aperture optical element 11 is at the first position (Position 1), as shown in FIG.
L ₁ is 1 mm, and the numerical aperture (NA) of the objective lens 4 is 0.6. In addition, the aperture optical element 11
2 is in the second position (Position 2), as shown in FIG.
As shown in FIG. 8, L ₂ is 3 mm and the numerical aperture (NA) of the objective lens 4 is 0.37. The lens data in this case is as shown in [Table 18] to [Table 20] below.

[0131]

[Table 18]

[0132]

[Table 19]

[0133]

[Table 20]

[0134]

As described above, in the optical pickup device according to the present invention, one surface is arranged on the divergent optical path between the light source and the objective lens and the other surface is the entire surface. The numerical aperture of the objective lens can be changed by moving the aperture optical element, which is formed as a light transmitting surface, in the optical axis direction of the light beam incident on the objective lens.

Therefore, in this optical pickup device, the numerical aperture of the objective lens can be changed to a value corresponding to the thickness of each transparent substrate of a plurality of types of optical recording media in which the thickness of the transparent substrate is different.

The light transmitting surface, which is the other surface of the aperture optical element, may be an aspherical surface for correcting the aberration generated in the transparent substrate of the optical recording medium.

That is, according to the present invention, the device configuration is complicated,
It is possible to provide an optical pickup device capable of favorably recording and reproducing information signals on optical recording media having different transparent substrate thicknesses without causing an increase in size.

[Brief description of drawings]

FIG. 1 is a perspective view showing a main part of an optical pickup device according to the present invention.

FIG. 2 is a side view showing a configuration of a main part of an optical pickup device according to the present invention configured by using a laser coupler.

FIG. 3 is a side view schematically showing the operation principle when the numerical aperture of the objective lens is increased in the optical pickup device.

FIG. 4 is a side view schematically showing the operation principle when the numerical aperture of the objective lens is reduced in the optical pickup device.

FIG. 5 is a trihedral view showing the shape of an aperture optical element that constitutes the above optical pickup device, in which the peripheral edge portion of the aperture stop surface is a conical tapered surface portion.

FIG. 6 is a vertical cross-sectional view showing the shape of the aperture optical element.

FIG. 7 is a vertical cross-sectional view illustrating the operation of the aperture optical element.

FIG. 8 is a vertical cross-sectional view showing another example of the shape of the aperture optical element.

FIG. 9 is a vertical cross-sectional view showing a shape when an aberration correction surface is provided in the aperture optical element.

FIG. 10 is a vertical cross-sectional view showing a shape when power is applied to an aberration correction surface in the aperture optical element.

FIG. 11 is a vertical cross-sectional view showing the shape of an aperture optical element that constitutes the above optical pickup device, in which the peripheral edge portion of the aperture stop surface serves as a light shielding processing portion.

FIG. 12 is a trihedral view showing the shape of an aperture optical element that constitutes the above optical pickup device, in which the aperture on the aperture stop surface is elliptical.

FIG. 13 is a trihedral view showing the shape of an aperture optical element that constitutes the above optical pickup device, in which the peripheral edge portion of the aperture stop surface is a toric surface portion.

FIG. 14 is a side view showing a first example of a mechanism for moving and operating the aperture optical element in the optical pickup device.

FIG. 15 is a side view showing a second example of a mechanism for moving and operating the aperture optical element in the optical pickup device.

FIG. 16 is a side view showing a third example of a mechanism for moving and operating the aperture optical element in the optical pickup device.

FIG. 17 is a perspective view showing a shape of a cam groove which is a main part of a third example of a mechanism for moving and operating the aperture optical element in the optical pickup device.

FIG. 18 is an enlarged perspective view of an essential part showing the shape of the essential part of the cam groove.

FIG. 19 is a side view showing a configuration of a portion from the light source to the collimator lens when the aperture optical element is arranged between the light source and the collimator lens in the optical pickup device.

FIG. 20 is an optical pickup device in the case where the aperture optical element is arranged between the light source and the collimator lens and at a position (L ₁ , NA large) 5 mm from the light source, the light source reaches the objective lens. It is a side view which shows the structure of a part.

FIG. 21 is a diagram showing the optical pickup device in the case where the aperture optical element is arranged between the light source and the collimator lens and at a position (L ₁ , NA large) 5 mm from the light source, the light source reaches the collimator lens. It is a side view which shows the structure of a part.

FIG. 22 is a view from the light source to the collimator lens when the aperture optical element is arranged between the light source and the collimator lens and at a position 4 mm (L ₁ , NA large) from the light source in the optical pickup device. It is a side view which shows the structure of a part.

FIG. 23 is an optical pickup device of the present invention, in which the aperture optical element is arranged between the light source and the collimator lens and at a position 3 mm (L ₁ , NA large) from the light source, the light source reaches the collimator lens. It is a side view which shows the structure of a part.

FIG. 24 is a view from the light source to the collimator lens when the aperture optical element is arranged at a position (L ₁ , NA large) between the light source and the collimator lens and 1 mm from the light source in the optical pickup device. It is a side view which shows the structure of a part.

FIG. 25 is a side view showing the configuration (NA size) in the vicinity of the objective lens when the aperture optical element is arranged between the light source and the collimator lens in the optical pickup device.

FIG. 26 is a view from the light source to the objective lens in the case where the aperture optical element is arranged between the light source and the collimator lens and at a position (L ₂ , NA small) 10 mm from the light source in the optical pickup device. It is a side view which shows the structure of a part.

FIG. 27 is a view from the light source to the collimator lens when the aperture optical element is arranged between the light source and the collimator lens and at a position (L ₂ , NA small) 10 mm from the light source in the optical pickup device. It is a side view which shows the structure of a part.

FIG. 28 is a diagram showing the optical pickup device in the case where the aperture optical element is disposed between the light source and the collimator lens at a position (L ₂ , NA small) 3 mm from the light source, the light source reaches the collimator lens. It is a side view which shows the structure of a part.

FIG. 29 is a side view showing a configuration (small NA) in the vicinity of the objective lens when the aperture optical element is arranged between the light source and the collimator lens in the optical pickup device.

[Explanation of symbols]

2 semiconductor laser, 2a, 22 laser chip (light source), 3 beam splitter, 4 objective lens, 5 photodetector, 6a 1st optical disk, 6b 2nd optical disk, 7 light transmitting surface, 7a aberration correction surface, 7b power Aberration correction surface, 8 apertures, 11 aperture optical elements, 12
Tapered surface portion, 12a light shielding processing portion, 23 beam splitter prism, 25 light detecting portion, 27 integrated element (laser coupler)

Claims (7)

[Claims] 1. A light source, an objective lens for condensing a light beam emitted from the light source on a signal recording surface of an optical recording medium, and a light detecting means for detecting reflected light of the light beam from the signal recording surface. An aperture optical element disposed on a divergent optical path between the light source and the objective lens, one surface of which is an aperture stop surface and the other surface of which is a light transmission surface over the entire surface; An optical pickup device, comprising: a moving operation means for moving the element in the optical axis direction of the light flux. 2. The aperture stop surface of the aperture optical element is such that a peripheral side portion is a conical tapered surface portion, and an inner side portion surrounded by the tapered surface portion corresponds to the opening portion. Item 1. The optical pickup device according to item 1. 3. The optical pickup device according to claim 2, wherein the aperture optical element is aligned and positioned by supporting the tapered surface portion from the peripheral side. 4. The aperture stop surface of the aperture optical element is configured such that a peripheral side portion is a light shielding processing portion, and an inner side portion surrounded by the light shielding processing portion corresponds to the opening portion. 1. The optical pickup device described in 1. 5. The aperture stop surface of the aperture optical element is configured such that a peripheral side portion thereof is a curved surface portion, and an inner side portion surrounded by the curved surface portion corresponds to the opening portion. Optical pickup device. 6. The optical pickup device according to claim 1, wherein a light transmitting surface, which is the other surface of the aperture optical element, is an aspherical surface for correcting aberration occurring in the transparent substrate of the optical recording medium. 7. The optical pickup device according to claim 6, further comprising a lateral movement operating means for moving the aperture optical element in a direction perpendicular to the optical axis of the light beam.