JP2002133698A - Manufacture method of information recording and reproducing apparatus optical element for information recording and reproducing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacture method of small and high efficiency information recording and reproducing apparatus narrow in interval between an optical element for an information recording and reproducing, and an information recording medium, and the optical element for the information recording and reproducing apparatus. SOLUTION: In the information recording and reproducing apparatus 100, a roughly hemispherical shape a convex spherical lens 113 is arranged between an object lens 112 and the transparent protective layer of an information recording medium 105. Both operations of a focusing operation stabilizing the interval between the convex spherical lens 113 and the transparent protective layer and a tracking operation moving the optical axis of the object lens 112 and the convex spherical lens 113 along the information track provided on the information recording medium 105 are minutely performed with a jogging actuator 104 and the focusing operation and the tracking operation are roughly performed with a coarse actuator 101. Therefore a high-density record and reproduction can be conducted and the efficiency of light can be enhanced and it is equipped for higher accuracy of the amount of shift caused from the higher density and higher NA of an optical information recording medium 105.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an information recording / reproducing apparatus and a method for manufacturing an optical element for an information recording / reproducing apparatus. More specifically, the distance between the information recording / reproducing optical element and the information recording medium is small, small, and high. The present invention relates to an efficient information recording / reproducing apparatus and a method for manufacturing an optical element for an information recording / reproducing apparatus.

[0002]

2. Description of the Related Art Conventionally, an optical pickup for an optical memory has
As shown in FIG. 23, the semiconductor laser 1 includes a linearly polarized semiconductor laser 1, a collimator lens 2, a polarizing beam splitter 3, a quarter-wave plate 4, an objective lens 5, a condenser lens 6, a photodiode 7, and the like. The light having a polarization parallel to the plane of FIG. 23 emitted from the laser 1 is converted into a parallel light by the collimator lens 2 and is incident on the polarization beam splitter 3.

The parallel light incident on the polarizing beam splitter 3 is converted from linearly polarized light into circularly polarized light by an optical isolator 8 composed of the polarizing beam splitter 3 and the quarter-wave plate 4, and is incident on the objective lens 5. Then, the light is focused as a spot on the recording surface of the optical disk 9 by the objective lens 5.

When the light incident on the optical disk 9 is reflected on the recording surface, the direction of rotation of the circularly polarized light changes and is incident on the quarter-wave plate 4 via the objective lens 5, When passing through the wave plate 4, the light is converted into light perpendicular to the plane of FIG. 23 and is incident on the polarization beam splitter 3. The light incident on the polarization beam splitter 3 is reflected by the polarization beam splitter 3 and is incident on the condenser lens 6, is condensed by the condenser lens 6, and is incident on the photodiode 7.
Although the optical pickup is actually provided with optical components for focus detection and track detection, it is omitted here. That is, the optical disc 9 records information by a difference in reflectance.

In the optical pickup having the above-described configuration, the spot size of the light focused on the optical disk 9 can be obtained only up to the wavelength of the light due to the diffraction limit of the light.
This spot size W can be expressed as follows.

W∝λ / sin θ ′ (1) Here, θ ′ is the exit angle of the objective lens 5, and has a relationship of NA = sin θ ′ with the NA (numerical aperture) of the objective lens 5. . Λ is the wavelength of light.

Therefore, conventionally, as described in Japanese Patent Application Laid-Open No. 5-189796, a hemispherical lens (solid immersion lens) is provided between an objective lens and a recording medium as in a liquid immersion method of a microscope. In order to increase the effective NA, a configuration in which a hemispherical lens (solid immersion lens) is inserted between an objective lens and a recording medium has been proposed for the purpose of increasing the effective NA. .

In this configuration, as shown in FIG. 24, the solid immersion lens 11 is disposed between the objective lens 12 and the recording medium 13 and the solid immersion lens 11 is disposed below the recording medium 13 with respect to the wavelength of light or less. It is arranged close to. This utilizes that the spot size of the light condensed on the end surface of the solid immersion lens 11 on the recording medium 13 side is proportional to the reciprocal of the refractive index of the solid immersion lens 11. In this case, the spot size W ′ is given by the following equation, where n is the refractive index of the solid immersion lens 11.

W′∝λ / nsin θ ′ (2) That is, the one described in Japanese Patent Application Laid-Open No. Hei 5-189796 has a solid immersion lens (hemispherical lens) 11
The reproduction is performed using near-field light by setting the distance between the optical disc and the recording medium 13 to be about the wavelength of light or less.

However, in the conventional general information recording / reproducing apparatus, the distance between the recording medium and the lens closest to the recording medium has a value larger than the wavelength of light. This is due to problems such as dust and dust and the problem of the removable nature of the recording medium.
(Numerical aperture) of about 0.8 to 0.9, and an interval of several tens
This is because the configuration is about μm or more. Therefore, such a general information recording / reproducing apparatus does not change the configuration of an objective lens and another lens, but uses normal propagation light for recording / reproducing information without using near-field light. I have.

[0011]

However, in such a conventional technique, the effective NA is increased,
In order to perform high-density recording / reproduction by reducing the spot size and to achieve miniaturization and high efficiency, there is still a need for improvement.

That is, in the information recording / reproducing apparatus,
During information recording / reproducing, the distance between the lens and the information recording medium must always be kept within the focal depth range of the lens. Therefore, it is necessary to perform so-called focusing control in which the actuator is controlled at a predetermined interval using an actuator. In addition, it is necessary to perform so-called tracking control for controlling the lens to always follow the information track on the information recording medium. Further, since the information recording medium is sometimes taken in and out of the information recording / reproducing apparatus, a coarse movement actuator for retracting the swing arm to a position where the information recording medium is not hindered is required.

When the recording density of the information recording medium is increased, the depth of focus of the lens is reduced and the track width is also reduced. Therefore, it is necessary to perform focusing control and tracking control more precisely.

[0014] However, the above-mentioned conventional technique cannot appropriately respond to these demands, and needs to be improved.

Therefore, according to the first aspect of the present invention, a light beam emitted from a light source is irradiated through a transparent protective layer of an information recording medium by an objective lens provided at the tip of a swing arm to transfer information to the recording layer. When performing recording / reproducing, a substantially hemispherical convex spherical lens is provided between the objective lens and the transparent protective layer of the information recording medium, and a focusing operation for keeping the distance between the convex spherical lens and the transparent protective layer constant, The fine movement actuator performs both the tracking operation of moving the optical axis of the lens and the convex spherical lens along the information track provided on the information recording medium finely, and the focusing operation and the tracking operation are roughly performed by the coarse movement actuator. By doing so, high-density recording / reproduction can be performed, light use efficiency can be improved, and optical information recording media can be made denser and higher NA. And its object is to provide an information recording and reproducing apparatus capable of corresponding to the high accuracy of the rotation amount.

According to a second aspect of the present invention, the objective lens and the convex spherical lens are formed as an integral optical element, thereby making it unnecessary to align the two lenses.
It is an object of the present invention to provide an information recording / reproducing apparatus which can reduce the size and thickness of the apparatus.

According to a third aspect of the present invention, at least one of an optical path separating means for separating an optical path and a condensing means for condensing a light beam with respect to an objective lens or an optical element in which the objective lens and the convex spherical lens are integrated. An object of the present invention is to provide an information recording / reproducing apparatus which can eliminate the need for alignment by providing one of them integrally, and can reduce the size and thickness of the apparatus.

According to a fourth aspect of the present invention, the surface of the convex spherical lens through which light passes on the information recording medium side is formed as a concave or convex surface, and the peripheral portion of the surface through which the light passes is formed as a flat or curved surface. By doing so, even if the convex spherical lens side and the information recording medium come into contact with each other due to the mechanical characteristics of the information recording medium itself or an external impact, it is possible to prevent the convex spherical lens itself from being damaged, It is an object of the present invention to provide an information recording / reproducing apparatus which can protect an entire mechanism including a fine actuator and a coarse actuator by reducing an impact.

According to a fifth aspect of the present invention, a projection is formed on a portion of the convex spherical lens on the information recording medium side where light does not pass, so as to protrude higher on the information recording medium side than a portion on which light passes.
By giving the projections a shock absorbing function, even if the convex spherical lens side and the information recording medium come into contact with each other due to the mechanical characteristics of the information recording medium itself or an external impact, the convex spherical lens itself will be damaged. It is an object of the present invention to provide an information recording / reproducing apparatus capable of suppressing the influence of these collisions and of protecting the entire mechanism including the fine movement actuator and the coarse movement actuator.

According to a sixth aspect of the present invention, at least one surface of the objective lens and the convex spherical lens is aspherical.
Provided is an information recording / reproducing apparatus which can prevent the convex spherical lens itself from being damaged even when the convex spherical lens side comes into contact with the information recording medium due to mechanical characteristics of the information recording medium itself or an external impact. It is intended to be.

According to the present invention, the objective lens and the convex spherical lens can be formed by a lens processing method using a semiconductor by forming the diameters of the objective lens and the convex spherical lens smaller than 1 mm. It is an object of the present invention to provide an information recording / reproducing apparatus which is small and thin and which is inexpensive.

According to an eighth aspect of the present invention, the coarse movement actuator performs a coarse movement operation by rotating the swing arm, and the fine movement actuator moves along the information track while rotating to correct the skew of the information track. By operating in this way, more accurate tracking is possible, suppressing signal errors, and more appropriately responding to the higher precision of the movement amount due to the higher density and higher NA of optical information recording media. It is an object of the present invention to provide an information recording / reproducing apparatus capable of performing the following.

According to a ninth aspect of the present invention, an inexpensive and small-sized information recording / reproducing apparatus is provided by using an electrostatic, piezoelectric, electromagnetic induction or ultrasonic actuator as a fine movement actuator. It is an object.

According to a tenth aspect of the present invention, the distance between the convex spherical lens and the information recording medium is set to several tens μm or more so that the information recording medium can be easily and easily inserted into and out of the information recording and reproducing apparatus. Another object of the present invention is to provide an information recording / reproducing apparatus capable of suppressing a signal error due to dust and dirt.

According to an eleventh aspect of the present invention, a small-sized actuator according to any one of the first to tenth aspects and optical components such as an objective lens and a convex spherical lens are manufactured by using a photolithography and an etching technique, so that a small-sized actuator is provided. An object of the present invention is to provide a method for manufacturing an optical element for an information recording / reproducing apparatus, which can easily manufacture an optical element and highly accurately align a lens group and can manufacture a large number of optical elements at once at low cost. And

[0026]

According to a first aspect of the present invention, there is provided an information recording / reproducing apparatus for irradiating a light beam emitted from a light source through a transparent protective layer of an information recording medium with an objective lens provided at a tip of a swing arm. An information recording / reproducing apparatus for recording / reproducing information on / from the recording layer, wherein a substantially hemispherical convex spherical lens provided between the objective lens and the transparent protective layer of the information recording medium; Both a focusing operation for keeping the distance between the convex spherical lens and the transparent protective layer constant, and a tracking operation for moving the optical axes of the objective lens and the convex spherical lens along the information track provided on the information recording medium. By providing a fine movement actuator that performs the operation finely, and a coarse movement actuator that roughly performs the focusing operation and the tracking operation, We have achieved the target.

According to the above construction, the light beam emitted from the light source is radiated through the transparent protective layer of the information recording medium by the objective lens provided at the tip of the swing arm to record and reproduce information on the recording layer. In performing this, a substantially hemispherical convex spherical lens is provided between the objective lens and the transparent protective layer of the information recording medium, and a focusing operation for maintaining a constant distance between the convex spherical lens and the transparent protective layer; Since both operations of the tracking operation for moving the optical axis of the lens along the information track provided on the information recording medium are finely performed by the fine movement actuator, and the focusing operation and the tracking operation are roughly performed by the coarse movement actuator, While being able to perform high density recording and reproduction,
The light use efficiency can be improved, and it is possible to cope with higher precision of the movement amount due to the higher density and higher NA of the optical information recording medium.

In this case, for example, the objective lens and the convex spherical lens may be formed as an integrated optical element.

According to the above configuration, since the objective lens and the convex spherical lens are formed as an integrated optical element, it is not necessary to align the two lenses, and the apparatus is made small and thin. be able to.

Further, for example, as described in claim 3, the information recording / reproducing apparatus is arranged such that the optical path passes through the objective lens or the optical element in which the objective lens and the convex spherical lens are integrated. At least one of the light path separating means for separating light and the light collecting means for collecting the light beam may be integrally provided.

According to the above arrangement, at least one of the optical path separating means for separating the optical path and the light collecting means for condensing the light beam with respect to the objective lens or the optical element in which the objective lens and the convex spherical lens are integrated. Since one of them is provided integrally, the alignment can be made unnecessary and the device can be made small and thin.

Further, for example, in the convex spherical lens, the surface of the convex surface of the information recording medium through which light passes is formed as a concave surface or a convex surface, and the surface through which the light passes. May be formed as a flat surface or a curved surface.

According to the above configuration, the surface of the convex spherical lens through which light on the information recording medium side passes is formed as a concave or convex surface, and the periphery of the surface through which the light passes is formed as a flat surface or a curved surface. Therefore, even if the convex spherical lens side and the information recording medium come into contact with each other due to the mechanical characteristics of the information recording medium itself or an external impact, it is possible to prevent the convex spherical lens itself from being damaged, The entire mechanism including the fine actuator and the coarse actuator can be protected by reducing the impact due to the collision.

For example, as described in claim 5, the convex spherical lens protrudes to a portion of the information recording medium through which light does not pass so as to be higher toward the information recording medium than a portion through which light passes. The projection may be formed, and the projection may have a shock absorbing function.

According to the above arrangement, a projection is formed on a portion of the convex spherical lens on the side of the information recording medium through which light does not pass, so as to protrude higher on the information recording medium side than on a portion through which light passes. The absorption function prevents the convex spherical lens itself from being damaged even if the convex spherical lens side comes into contact with the information recording medium due to the mechanical characteristics of the information recording medium itself or an external impact. In addition, the impact caused by these collisions can be reduced to protect the entire mechanism including the fine actuator and the coarse actuator.

Further, for example, the objective lens and the convex spherical lens may have at least one aspheric surface.

According to the above configuration, at least one surface of the objective lens and the convex spherical lens is aspherical, so that the convex spherical lens side and the information recording medium come into contact with each other due to mechanical characteristics of the information recording medium itself or an external impact. Even in this case, it is possible to prevent the convex spherical lens itself from being damaged.

For example, the objective lens and the convex spherical lens may be formed such that the diameter of the lens is smaller than 1 mm.

According to the above configuration, since the diameters of the objective lens and the convex spherical lens are smaller than 1 mm, the objective lens and the convex spherical lens can be formed by a lens processing method using a semiconductor. In addition, the optical system can be made small and thin, and inexpensive.

Further, for example, as set forth in claim 8, the coarse movement actuator performs the coarse movement by rotating the swing arm, and the fine movement actuator performs a rotation movement to rotate the information track. It may operate so as to follow the information track while correcting the skew.

According to the above configuration, the coarse movement actuator performs the coarse movement operation by rotating the swing arm, and the fine movement actuator performs the rotational movement so as to follow the information track while correcting the skew of the information track. Since it operates, it enables more accurate tracking, suppresses signal errors, and responds more appropriately to higher-precision moving distances by increasing the density of optical information recording media and increasing NA. Can be.

Further, for example, the fine movement actuator may be an electrostatic actuator, a piezoelectric actuator, an electromagnetic induction actuator, or an ultrasonic actuator.

According to the above configuration, since the actuator of the electrostatic type, the piezoelectric type, the electromagnetic induction type, or the ultrasonic type is used as the fine movement actuator, the information recording / reproducing apparatus can be made more inexpensive and smaller. Can be.

Further, for example, in the information recording / reproducing apparatus, an interval between the convex spherical lens and the information recording medium may be several tens μm or more.

According to the above arrangement, since the distance between the convex spherical lens and the information recording medium is set to several tens μm or more, it is possible to easily and easily put the information recording medium in and out of the information recording / reproducing apparatus. In addition, it is possible to suppress signal errors due to dust and dirt.

The method for producing an optical element for an information recording / reproducing apparatus according to the invention of claim 11 is the method for producing an optical element for an information recording / reproduction apparatus according to any one of claims 1 to 10.
The above object is achieved by manufacturing the fine movement actuator and the optical components such as the objective lens and the convex spherical lens described above, using photolithography and an etching technique.

According to the above configuration, the present invention is characterized in that:
Since the micro-movement actuator and the optical components such as the objective lens and the convex spherical lens described in No. 0 are manufactured by using the photolithography and the etching technology, it is easy to manufacture a small optical element and to precisely align the lens groups. In addition to this, a large number of optical elements can be manufactured at once at a low cost.

[0048]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferable limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.

FIGS. 1 to 3 show the first embodiment of the information recording / reproducing apparatus of the present invention. FIG. 1 shows the first embodiment of the information recording / reproducing apparatus of the present invention. 1 is a perspective view of a main part of an information recording / reproducing apparatus 100 according to the first embodiment.

In FIG. 1, an information recording / reproducing apparatus 100
Is a swing arm 102
Is mounted, and a pickup optical system 103 is mounted at the tip of the swing arm 102. As shown in FIGS. 2 and 3, a fine movement actuator 104 is attached to the pickup optical system 103, and an information recording medium 105 is disposed below the pickup optical system 103.

Although the layer structure of the information recording medium 105 is not shown, it is generally a protective layer / dielectric layer / recording layer / dielectric layer / reflective layer / substrate from the light incident side. The layer configuration of the information recording medium 105 to be recorded / reproduced in the form is not limited to the above-described layer structure. The information recording medium 105 is generally provided with a track groove for recording and reproducing information, but need not be a groove. The recording layer of the information recording medium 105 may be of a rewritable phase change type, may be of a type that can be written only once, or may be of a type in which a mark has already been written, such as a ROM. There may be. When a magneto-optical material is used as the rewritable material of the information recording medium 105, it can be coped with by adopting a configuration capable of applying a magnetic field when irradiating light. This can be dealt with by approaching from the back surface of the substrate of the information recording medium 105 or by forming a coil that generates magnetism on the surface of the pickup optical system 103 including the convex spherical lens 113 described later.

The information recording medium 105 is rotated at a constant rotational speed by a drive motor (not shown), and information is recorded and reproduced on the rotated information recording medium 105 by the pickup optical system 103.

The coarse movement actuator 101 includes a voice coil motor (not shown) that roughly moves the swing arm 102 in a direction crossing the track of the information recording medium 105, as shown by a double arrow in FIG. A piezoelectric element (not shown) for roughly controlling the pickup optical system 103 at an appropriate interval.

Although the coarse actuator 101 in the focus direction uses a piezoelectric element near the voice coil motor, it may be provided on the swing arm 102, and may be an electromagnetic induction type actuator instead of a piezoelectric element. An ultrasonic actuator may be used, and an actuator in consideration of restrictions such as the size of the entire element can be selected.

As shown in FIGS. 2 and 3, the fine movement actuator 104 performs fine movements of tracking and focusing at the position where the pickup optical system 103 is located.

Of the fine movement actuators 104, a pair of fine movement actuators 104 indicated by squares in FIG.
Is an actuator that slightly moves in the focus direction,
A pair of fine movement actuators 104 shown as rectangles
Is an actuator that slightly moves in the tracking direction. As the fine movement actuator 104, a piezoelectric element is used. The piezoelectric element has a configuration in which thin ceramic substrates are stacked, and the length of the piezoelectric element changes when a voltage is applied to each ceramic substrate. .
Piezoelectric elements change in the direction in which they are stacked when a voltage is applied.Therefore, a piezoelectric element for focusing is an element stacked in the optical axis direction, and a piezoelectric element for tracking is an optical axis. The elements are stacked in a direction perpendicular to the vertical direction.

In this embodiment, the shape of the piezoelectric element used in the fine actuator 104 is square and rectangular. However, the shape of the piezoelectric element is not limited to square or rectangular. For example, it may be cylindrical.

Then, the fine movement actuator 104 operates so as to balance the two piezoelectric elements in the focus direction so that the two piezoelectric elements do not shift in the optical axis direction, and similarly operates the two piezoelectric elements in the tracking direction. The piezoelectric element operates to balance.

In the present embodiment, the piezoelectric element used as the fine movement actuator 104 is of a laminated type, but may be of a bimorph type or of another type. .

Further, the fine movement actuator 104 is not limited to the piezoelectric element, but may be, for example, a piezoelectric element other than the piezoelectric element, an electromagnetic induction type actuator, or an ultrasonic actuator.

Further, an electrostatic actuator manufactured using a semiconductor process is suitable for small size and thin type, and can be manufactured by a manufacturing process similar to a microlens manufacturing process described later.

The pickup optical system 103 includes a semiconductor laser as a light source (not shown), a lens (not shown) for collimating light from the semiconductor laser, and a collimated light linearly polarized by the collimator lens.
A polarization beam splitter 110 that reflects light in a direction 12 and transmits linearly polarized light in a direction orthogonal to the linearly polarized light;
A quarter-wave plate 111, an objective lens 112, a convex spherical lens (solid immersion lens) 113, a spacer 114 inserted between the objective lens 112 and the convex spherical lens 113, a condenser lens and a light receiving element (not shown). It has.

That is, the pickup optical system 103
An objective lens 112 and a convex spherical lens 113 are provided via a hollow spacer 114.
Determines the distance between the objective lens 112 and the convex spherical lens 113 so that the focal position of the objective lens 112 is
13 are arranged. The convex spherical lens 113 and the information recording medium 105 are close to each other at a wavelength equal to or shorter than the wavelength of a semiconductor laser as a light source. A fine movement actuator 104 is arranged on the objective lens 112, and the fine movement actuator 104 is installed on the swing arm 102. On the swing arm 102, a polarizing beam splitter 110 is provided, and collimated light emitted from a semiconductor laser, which is a light source, and linearly polarized by a collimating lens, as shown in FIG.
Incident. Around the optical axis, no light blocking member such as the fine movement actuator 104 is arranged.

The light collimated by the collimating lens enters a polarizing beam splitter 110, is deflected by the polarizing beam splitter 110 to the lower side in FIG. 2, and enters an objective lens 112. The objective lens 112 causes the incident light to enter the convex spherical lens 113 as converged light and converge it on the bottom surface of the convex spherical lens 113. Then, the convex spherical lens 113 and the information recording medium 105 are, as described above,
Since it is close to the wavelength of the laser beam emitted by the semiconductor laser or less, the information recording medium 105 is irradiated with near-field light.
Record / reproduce.

Next, the operation of the present embodiment will be described. When the information recording / reproducing apparatus 100 takes the information recording medium 105 into the information recording / reproducing apparatus 1 and installs the information recording medium 105 at the center of the rotating mechanism, the swing arm 102 retracted to a position where it does not interfere with the installation of the information recording medium 105 is roughly moved. The actuator 101 sets the information recording medium 105 in the initial state by approaching the rotating information recording medium 105 in both the track direction and the focus direction.

At this time, the fine movement actuator 104 starts operating, and performs fine control of both tracking and focusing.

When the information recording / reproducing apparatus 100 finishes reading (reproducing) or writing (recording) data from the information recording medium 105 and takes out the information recording medium 105 from the information recording / reproducing apparatus 1, Arm 102
By operating the coarse motion actuator 101 in the track direction and the focus direction, it is retracted to a position where it does not come into contact with the information recording medium 105.

At this time, the information recording medium 105 may be contained in a cartridge to take measures against dust. In such a case, the cartridge is provided with a shutter, and the shutter is opened and closed in the information recording / reproducing apparatus 100.

As described above, the information recording / reproducing apparatus 1 collimates the light emitted from the semiconductor laser, which is the light source, with the collimating lens, makes the collimating light enter the objective lens 112 with the deflection beam splitter 110, The light is focused on the bottom surface of the spherical lens 113. Since the convex spherical lens 113 and the information recording medium 105 are close to each other at a wavelength equal to or less than the wavelength of the light emitted from the semiconductor laser, recording / reproduction of the information recording medium 105 is performed by near-field light.

That is, at the time of reproduction, the information recording / reproducing apparatus 1 transmits the reflected light from the information recording medium 105 through the convex spherical lens 113, the objective lens 112, the quarter-wave plate 111 and the polarizing beam splitter 110, and The light is condensed on a light receiving element (not shown) by a light collecting element (not shown) arranged on the beam splitter 110, and a light signal of the light receiving element is incident. At this time, the information recording / reproducing apparatus 1 performs focusing detection and tracking detection using a combination of a condenser lens and a light receiving element.

As described above, in the information recording / reproducing apparatus 100 of the present embodiment, the light beam emitted from the semiconductor laser as the light source is transmitted through the objective lens 112 provided at the tip of the swing arm 102 so that the information recording medium 105 is transparent. When recording and reproducing information on the recording layer by irradiating through the protective layer, a substantially hemispherical convex spherical lens 113 is provided between the objective lens 112 and the transparent protective layer of the information recording medium 105,
Both a focusing operation for keeping the distance between the convex spherical lens 113 and the transparent protective layer constant, and a tracking operation for moving the optical axis of the objective lens 112 and the convex spherical lens 113 along the information track provided on the information recording medium 105. The operation is finely performed by the fine movement actuator 104, and the focusing operation and the tracking operation are roughly performed by the coarse movement actuator 101.

Therefore, high-density recording / reproduction can be performed, and the light use efficiency can be improved, and the optical information recording medium 105 can be moved with high density and high NA so that the movement amount can be increased. can do.

FIG. 4 and FIG. 5 are diagrams showing a second embodiment of the information recording / reproducing apparatus of the present invention.

The present embodiment is applied to an information recording / reproducing apparatus similar to the information recording / reproducing apparatus 100 of the first embodiment, and in the description of the present embodiment, the first embodiment will be described. The same components as those in the embodiment are denoted by the same reference numerals, and the portions not shown in the drawings will be described using the reference numerals used in the first embodiment as needed.

FIG. 4 shows a second embodiment of the information recording / reproducing apparatus of the present invention.
FIG. 5 is an enlarged front view of a pickup optical system 121 of an information recording / reproducing apparatus 120 to which the embodiment of FIG.
3 is a bottom view of the pickup optical system 121 of FIG.

4 and 5, in the pickup optical system 121, an objective lens 122 and a convex spherical lens 123 are arranged on one substrate 124.
The fine movement actuator 104 is arranged on a substrate 124 including a lens 22 and a convex spherical lens 123. That is, the objective lens 122 and the convex spherical lens 123 are formed as an integrated optical element.

A quarter wave plate 124 and a polarization hologram (light condensing means, light path separating means) 12 having a condensing function are provided on the side of the objective lens 122 on the side of the fine movement actuator 104 on the substrate 124
5 are arranged. The polarization hologram 125 transmits linearly polarized light in a certain direction as it is, diffracts linearly polarized light in a direction orthogonal to the linearly polarized light, and the diffracted light becomes light to be collected by the light collecting function. This is a hologram (diffraction grating) having an optical path separating function and a light collecting function. The polarization hologram 125 is, specifically, an element in which birefringent materials are arranged in a lattice pattern with a pitch of several μm.

A fine movement actuator 104 and a mirror 126 are disposed on the swing arm 102. The fine movement actuator 104 is the same as the fine movement actuator 104 of the first embodiment.

The pickup optical system 121 includes a semiconductor laser as a light source, a collimating lens, a light receiving element, and the like (not shown) in addition to the above.

Unlike the first embodiment, the focal position of the lens group composed of the objective lens 122 and the convex spherical lens 123 is not on the bottom surface of the convex spherical lens 123 but on the recording layer of the information recording medium 105. , The convex spherical lens 123 and the information recording medium 105 have an interval of about several tens of μm.

The NA of the lens group is a value not exceeding “1” at the maximum. Information recording medium 10 of convex spherical lens 123
The surface on the 5 side has a configuration with a gentle curvature,
On the surface of the convex spherical lens 123, a protective layer 127 made of, for example, diamond-like carbon is provided. The information recording medium 105 of the convex spherical lens 123
The surface on the side may be provided with an antireflection film.

The optical pickup optical system 121 converts the linearly polarized light emitted from the semiconductor laser and collimated by the collimating lens into an optical axis as shown by a broken line in FIG.
Polarization hologram 1 located at the bottom of FIG.
The light is reflected in 25 directions, passes through the polarization hologram 125 and the quarter-wave plate 124, and is incident on the objective lens 122.
The objective lens 122 makes the incident light incident on the convex spherical lens 123 as converging light, and condenses it on the recording layer of the information recording medium 105.

At the time of reproduction, the information recording / reproducing apparatus 120 transmits the reflected light from the information recording medium 105 to the convex spherical lens 1.
23, through the objective lens 122, the ４ wavelength plate 1
At 24, the light becomes a polarized light orthogonal to the light incident on the information recording medium 105, is diffracted by the polarization hologram 125, and becomes condensed light. The information recording / reproducing device 120 makes the condensed light after diffraction pass outside the mirror 126 and enter a light receiving element (not shown) as an optical signal. At this time, the information recording / reproducing apparatus 120 performs focusing detection and tracking detection using a combination of the polarization hologram 125 and the light receiving element.

As described above, the information recording / reproducing apparatus 120 of the present embodiment includes the objective lens 122 and the convex spherical lens 123
Are formed on one substrate 124 as an integrated optical element.

Therefore, it is not necessary to align the two lenses, and the concession recording / reproducing apparatus 1
20 can be made small and thin.

The information recording / reproducing apparatus 1 of the present embodiment
Reference numeral 20 denotes a surface of the convex spherical lens 123 on the information recording medium 105 side having a curvature, and a protective layer 1 on the surface.
23, the convex spherical lens 123 should be used.
Is in contact with the information recording medium 105, the convex spherical lens 12
3 can be prevented from being scratched or partially chipped.

In this embodiment, the convex spherical lens 1
23 has a convex shape whose surface on the information recording medium 105 side protrudes toward the information recording medium 105, but only the lens portion of the convex spherical lens 130 on the information recording medium 105 side as shown in FIG. It may be concave. Also in this case, the protective layer 127 is provided on the entire surface.

In a configuration in which an objective lens and a convex spherical lens are arranged on both surfaces of one substrate, the objective lens has two curved surfaces, and one substrate has one curved surface of the objective lens and the other substrate has one curved surface. May have a configuration including two substrates on which a second curved surface and a convex spherical lens are formed.

FIG. 7 and FIG. 8 are diagrams showing a third embodiment of the information recording / reproducing apparatus of the present invention.

This embodiment is applied to an information recording / reproducing apparatus similar to the information recording / reproducing apparatus 100 of the first embodiment, and in the description of the present embodiment, the first embodiment will be described. The same components as those in the embodiment are denoted by the same reference numerals, and the portions not shown in the drawings will be described using the reference numerals used in the first embodiment as needed.

FIG. 7 shows a third embodiment of the information recording / reproducing apparatus of the present invention.
FIG. 8 is an enlarged front view of a pickup optical system 141 of an information recording / reproducing apparatus 140 to which the embodiment of FIG.
3 is a bottom view of the pickup optical system 141 of FIG.

In FIG. 7 and FIG. 8, the pickup optical system 141 has an objective lens 142 and a convex spherical lens 143 arranged on one substrate 144.
The fine movement actuator 104 is arranged on a substrate 144 including the convex lens 42 and the convex spherical lens 143.

A quarter-wave plate 145 and a polarization hologram 146 having a light condensing function are arranged on the substrate 144 on the side of the fine movement actuator 104 of the objective lens 142. The polarization hologram 146 transmits linearly polarized light in a certain direction as it is, diffracts linearly polarized light in a direction orthogonal to the linear polarized light, and the diffracted light becomes light to be collected by the light collecting function. This is a hologram (diffraction grating) having an optical path separating function and a light collecting function. Polarization hologram 1
Specifically, reference numeral 46 denotes an element in which birefringent materials are arranged in a lattice pattern with a pitch of several μm. Note that the polarization hologram 146 may not have a condensing function, and in this case, a lens having a condensing function is separately provided.

A fine movement actuator 104 and a mirror 147 are arranged on the swing arm 102. The fine movement actuator 104 is the same as the fine movement actuator 104 of the first embodiment.

The pickup optical system 141 includes a semiconductor laser as a light source, a collimator lens, a light receiving element, and the like (not shown) in addition to the above.

The focal position of the lens group composed of the objective lens 142 and the convex spherical lens 143 is the position of the recording layer of the information recording medium 105 as in the second embodiment. Information recording medium 105
It has an interval of about um. The NA of the lens group is a value that does not exceed “1” at the maximum. On the surface of the substrate 144 provided with the convex spherical lens 143 on the information recording medium 105 side, three projections 148 are provided.
8 is formed in the shape of a truncated cone. The protrusion 148
May be arranged at four corners of the surface of the substrate 144 on the information recording medium 105 side. Note that an antireflection film may be applied to the surface of the convex spherical lens 143 on the information recording medium 105 side.

The projection 148 is formed of a material that absorbs impact, and a protective layer 149 is provided on the surface of the projection 148. As a material for absorbing the impact of the projection 148, for example, an elastic body such as rubber, a gel-like substance, or the like can be used. The projection 148 has a structurally absorbing impact, for example, a nanometer order. One projection 148 may be formed by a group of minute projections. Protective layer 14
For 9, for example, a material such as diamond-like carbon can be used. The projection 148 is a convex spherical lens 14.
3, the surface of the convex spherical lens 143 can be prevented from directly contacting the information recording medium 105.

In the configuration in which the objective lens and the convex spherical lens are arranged on both surfaces of one substrate, the objective lens has two curved surfaces, as in the second embodiment, and the objective lens is provided on one substrate. One curved surface of the other substrate,
A configuration including two substrates on which a second curved surface and a convex spherical lens are formed may be employed.

The optical pickup optical system 141 converts the linearly polarized light emitted from the semiconductor laser and collimated by the collimating lens into an optical axis as shown by a broken line in FIG.
Polarization hologram 1 located below mirror 147 in FIG.
The light is reflected in the 46 direction, passes through the polarization hologram 146 and the quarter-wave plate 145, and is incident on the objective lens 142.
The objective lens 142 makes the incident light incident on the convex spherical lens 143 as converging light, and condenses it on the recording layer of the information recording medium 105.

The information recording / reproducing apparatus 140 transmits the reflected light from the information recording medium 105 to the convex spherical lens 1 during reproduction.
43, through the objective lens 142, the 1/4 wavelength plate 1
At 45, the light becomes a light in a polarization state orthogonal to the light incident on the information recording medium 105, and is diffracted by the polarization hologram 146 to be condensed light. The information recording / reproducing device 140 causes the condensed light after diffraction to enter a light receiving element (not shown) as an optical signal through the outside of the mirror 147. At this time, the information recording / reproducing apparatus 140 performs the focusing detection and the tracking detection with the combination of the polarization hologram 146 and the light receiving element.

In the information recording / reproducing apparatus 140, a projection 148 protruding from the convex spherical lens 143 toward the information recording medium 105 is provided on the surface of the substrate 144 on the information recording medium 105 side where the convex spherical lens 143 is provided. Even if the information recording medium 105 and the pickup optical system 141 come into contact with each other, the convex spherical lens 143 does not come into contact with the information recording medium 105, so that the convex spherical lens 143 is scratched, Can be prevented from being chipped, and the impact at the time of collision with the information recording medium 105 is absorbed by the projection 148, and the fine movement actuator 104 is prevented.
And other impacts can be reduced.

FIG. 9 to FIG. 11 are diagrams showing a fourth embodiment of the information recording / reproducing apparatus of the present invention.

This embodiment is applied to an information recording / reproducing apparatus similar to the information recording / reproducing apparatus 100 of the first embodiment, and in the description of the present embodiment, the first embodiment will be described. The same components as those in the embodiment are denoted by the same reference numerals, and the portions not shown in the drawings will be described using the reference numerals used in the first embodiment as needed.

FIG. 9 shows a fourth embodiment of the information recording / reproducing apparatus according to the present invention.
9 is an enlarged front view of the pickup optical system 151 of the information recording / reproducing apparatus 150 to which the embodiment is applied, FIG. 10 is a bottom view of the pickup optical system 151 of FIG. 9, and FIG. 11 is a view of the pickup optical system 151 of FIG. It is a bottom view which shows an actuator operation state.

9 and 10, the pickup optical system 151 includes an objective lens 152 and a convex spherical lens 153.
Are arranged on one substrate 154, and a focusing fine movement actuator 155 is arranged on the substrate 154 including the objective lens 152 and the convex spherical lens 153.

A quarter-wave plate 1 is provided on the side of the objective lens 152 of the substrate 154 on the side of the focusing fine actuator 155.
56 and a polarization hologram 157 having a condensing function are arranged. The polarization hologram 157 transmits linearly polarized light in a certain direction as it is, diffracts linearly polarized light in a direction orthogonal to the linear polarized light, and the diffracted light becomes light to be collected by the light collecting function. This is a hologram (diffraction grating) having an optical path separating function and a light collecting function.
The polarization hologram 157 is, specifically, an element in which birefringent materials are arranged in a lattice pattern with a pitch of several μm. Note that the polarization hologram 157 may not have a condensing function, and in this case, a lens having a condensing function is separately provided.

[0107] Focusing fine movement actuator 15
The 5 and 1/4 wavelength plate 156 and the polarization hologram 157 having a light condensing function are attached to the lower surface of the swing arm 102, and a fine movement actuator 158 for tracking is arranged on the upper surface of the swing arm 102. A substrate 159 is mounted on the upper surface of the tracking fine movement actuator 158, and on the upper surface of the substrate 159,
A mirror 160 is provided.

That is, the fine movement actuator 155 for focusing and the fine movement actuator 155 for tracking
Numeral 8 is disposed on both sides of the swing arm 102, and a pair of rectangles shown in FIG. 10 is a fine movement actuator 158 for tracking.
What is indicated by a pair of squares in FIG. 10 is the focusing fine movement actuator 155. The pair of tracking fine movement actuators 158 have different fine movement amounts and are different from each other, and the fine movement of each tracking fine movement actuator 158 causes the lens group to move the lens group of the tracking fine movement actuator 158 shown in FIG.
Makes a rotational motion about the rotational center of. And FIG.
The center of the optical axis is shifted from the rotation center of the tracking fine movement actuator 158 so that the center of the optical axis is shown at 0, and the position of the optical axis is indicated by a double arrow in FIG. As shown in the figure, fine movement is performed so as to draw an arc around the center of the optical axis.

The pickup optical system 151 includes a semiconductor laser as a light source, a collimating lens, a light receiving element, and the like (not shown) in addition to the above.

The focal position of the lens group composed of the objective lens 152 and the convex spherical lens 153 is the position of the recording layer of the information recording medium 105 as in the second embodiment. Information recording medium 105
It has an interval of about um. The NA of the lens group is a value that does not exceed “1” at the maximum. Three protrusions 161 are provided on the surface of the substrate 154 on which the convex spherical lens 153 is provided on the information recording medium 105 side.
1 is formed in a truncated cone shape. The protrusion 161
May be arranged at four corners of the surface of the substrate 154 on the information recording medium 105 side. Note that an anti-reflection film may be applied to the surface of the convex spherical lens 153 on the information recording medium 105 side.

The projection 161 is formed of a material that absorbs impact, and a protective layer 162 is provided on the surface of the projection 161. As a material for absorbing the impact of the projection 161, for example, an elastic body such as rubber, a gel-like substance, or the like can be used. The projection 161 has a structurally absorbing impact, for example, a nanometer-order structure. One protrusion 161 may be formed by a group of minute protrusions. Protective layer 16
For 2, a material such as diamond-like carbon can be used, for example. The protrusion 161 is provided on the convex spherical lens 15.
3, the surface of the convex spherical lens 153 can be prevented from directly contacting the information recording medium 105.

In the configuration in which the objective lens and the convex spherical lens are arranged on both sides of one substrate, the objective lens has two curved surfaces, as in the second embodiment, and the objective lens is provided on one substrate. One curved surface of the other substrate,
A configuration including two substrates on which a second curved surface and a convex spherical lens are formed may be employed.

The optical pickup optical system 151 is attached to the tip of the swing arm 102, and the information recording medium 105 includes, as described in the first embodiment,
The track groove is formed, and the optical pickup optical system 1
The reference numeral 51 normally moves the optical axis along the track groove, but as shown in FIGS. 1 and 11, the swing arm 102 moves in an arc.

Therefore, as shown in FIG. 11, a so-called skew occurs in which the angle between the tangential direction of the track groove and the swing arm 102 changes depending on the radius position of the information recording medium 105, which affects the tracking error signal. There is. For example, when performing tracking detection by the push-pull method, the phase ratio of light reflected from different heights of the track grooves is used to detect the left / right area ratio (light intensity ratio) of a weak light intensity and a strong light intensity. However, the skew rotates the left-right symmetry, and the detection signal is disturbed.

Therefore, in the pickup optical system 151 of the present embodiment, as shown by a double arrow in FIG.
The fine movement actuator 158 for tracking changes so that the angle formed between the tangential direction of the track groove and the swing arm falls within a certain range so that the left-right symmetry of the signal light from the optical disk 05 is maintained. FIG. 9 shows a state in which the tracking fine movement actuator 158 fluctuates and follows the track B.

FIGS. 12 to 22 are views showing a fifth embodiment of the method of manufacturing an optical element for an information recording / reproducing apparatus according to the present invention.

In the present embodiment, a microlens is manufactured by using the objective lens and the convex spherical lens of the optical pickup optical system shown in FIG. 9 on one substrate by using a photolithography technique and a dry etching technique. The fine movement actuator is an electrostatic actuator manufactured by finely processing a Si substrate.

First, an objective lens is formed on one side of the substrate 200 shown in FIG. 12 in the following procedure. That is, FIG.
As shown in (1), a photosensitive material 201 is applied on a substrate 200. As the substrate 200, BK7 (wavelength 768.2n)
The index of refraction at m is 1.5115).
Is set to a length at which the minimum spot size can be obtained on the information recording medium with the optical pickup optical system to be formed. The thickness of the photosensitive material 201 is determined by the height of the objective lens formed on the substrate 200 and the ratio (selectivity) of the etching rate of the substrate material to which the photosensitive material 201 is to be later etched and the etching rate of the resist. Set by. For example, when both etching rates are equal (selection ratio 1), the height of the resist is made substantially equal to the height of the objective lens to be formed. When the etching rate of the substrate material is twice as large as the etching rate of the resist (selectivity 2)
First, the height of the resist is set to １ ／ of the height of the objective lens. As the photosensitive material 201 applied on the substrate 200, a photoresist or a photosensitive dry film used in normal semiconductor manufacturing can be used. Specifically, OFPR-800 (positive resist), OMR
-85 (negative resist) or the like can be used. The shape of the photomask used in the step of transferring the shape to the resist (photolithography step) changes depending on the selection of the positive type or the negative type, but the basic forming procedure does not change. In this embodiment mode, a case where a positive resist is used will be described.

The resin is irradiated with light through a mask in which the transmittance distribution is set so that the same shape as the objective lens (in the case of a selection ratio of 1) can be formed on the resist formed on the substrate 200. When exposed and then developed,
As shown in FIG. 13, the resin in which the concave portion 202 having the same shape as the objective lens (in the case of the selection ratio of 1) is formed on the substrate 200 remains.

Using the concave lens-shaped resin 201 thus formed as a mask, the substrate glass 200 is
Etching (anisotropic etching) is performed in a direction perpendicular to the direction of FIG. 2 to form a concave lens-shaped portion 203 serving as an objective lens on the substrate 200 as shown in FIG.

In this case, the etching is performed by using a semiconductor
Use dry etching commonly used in process
Specifically, reactive ion etching (RI
E), electron cyclotron resonance etching (ECR)
Etc. can be used. Also for dry etching
The selected gas depends on the substrate material.
When the plate material is glass, CF_Four , CHF_Three Using
Can be Adjustment of etching rate and selectivity
In order to perform the etching properly, the etching gas _Two , O
_Two , Ar or the like may be mixed.

Next, the concave lens shape portion 20 of the substrate 200
3, a material having a higher refractive index than the substrate 200, for example, L
aF2 (refractive index at a wavelength of 768.2 nm: 1.7335)
Or SFS1 (refractive index 1.8 at a wavelength of 768.2 nm)
927) is buried by a sputtering method. That is, as shown in FIG. 15, a sputtered film 204 is formed on the surface of the substrate 200 on which the concave lens shape 203 is formed by a sputtering method using a material having a desired refractive index as a target. By backing and flattening, as shown in FIG. 16, the sputtered film 204 is selectively left on the concave lens-shaped portion 203 to form the objective lens 205 having an aspherical shape.

In addition to the above method, a resin material having a high refractive index is embedded in the concave lens-shaped portion 203, a transparent flat substrate is bonded thereon, and then polished to a desired height to form the objective lens 205. May be.

Next, a convex spherical lens is formed on the opposite side of the substrate 200 on which the objective lens 205 is formed by the following procedure. The formation of the convex spherical lens is basically the same as the formation of the objective lens 205 described above. The procedure is as follows.

That is, the objective lens 205 of the substrate 200
As shown in FIG. 17, a photosensitive material 206 is applied to a surface on which a convex spherical lens is formed, which is a surface on the opposite side to the surface on which is formed, and then a positive resist is applied. A resist is formed thereon such that a concave portion 207 having a convex spherical lens shape is formed after etching.

Next, by the same etching method as described above,
As shown in FIG. 18, a concave lens shape portion 208 serving as a convex spherical lens is formed on a substrate 200.

Next, the concave lens shape portion 20 of the substrate 200
8, a material having a higher refractive index than the substrate 200, for example, La
F2 (refractive index at a wavelength of 768.2 nm: 1.7335) or SFS1 (refractive index at a wavelength of 768.2 nm: 1.89)
27) is embedded to form a convex spherical lens 209.
This convex spherical lens 209 has a hemispherical shape. Also in this case, the concave lens shape portion 20 in the case of the objective lens 205 is used.
Similarly to the method of embedding No. 3, it can be manufactured by a sputtering method, and if necessary, etch back is performed to make the surface of the convex spherical lens 209 flat.

In addition to the above method, a resin material having a high refractive index is embedded in the concave lens-shaped portion 208, a transparent flat substrate is adhered thereon, and polished to a desired height. May be formed.

Next, on the surface of the substrate 200 on which the convex spherical lens 209 is formed, a projection 210 is formed in a planar shape by the following procedure.

A photolithography step is performed again on the surface of the substrate 200 on which the convex spherical lens 209 is formed, a projection-like resist is formed, and dry etching is performed to form the projection 210. In addition to the above-described method, the protrusion 210 may be directly formed as the protrusion 210 by photolithography of a rubber-based resist material.

Further, on the surface of the projection 210, FIG.
As shown in FIG. 9, the protective layer 211 is formed by sputtering.

Next, as shown in FIG. 20, a quarter wavelength plate 2 is formed on the surface of the substrate 200 on which the objective lens 205 is formed.
12 is formed. The 波長 wavelength plate 212 may be formed by laminating a thin sheet-like member, or may be formed by deposition by vapor deposition.

Further, on the 波長 wavelength plate 212, FIG.
As shown in FIG. 1, a polarization hologram 21 having a condensing function
3 is manufactured. The polarization hologram 213 is formed by forming a lattice with a birefringent material on the substrate 200, and diffracts according to the direction of linearly polarized light or transmits without diffracting. The angle at which the polarization hologram 213 diffracts depends on the pitch of the grating. In the optical pickup optical system 151 shown in FIG. 9, the diffracted light avoids the polarization hologram 157, that is, the mirror 160 on the polarization hologram 213. Such a pitch. Furthermore, the polarization hologram 21
In No. 3, since it is necessary to have a light condensing function, the grating is not a linear shape but a grating pattern having a certain curvature. The lattice pattern of the polarization hologram 213 is obtained by calculating the shape of the polarization hologram 213 according to the position of light collection and the like, and the polarization hologram 213 is manufactured by photolithography and dry etching based on the calculated lattice pattern.

As shown in FIG. 21, the manufactured polarization hologram 213 is bonded to a substrate 200 having an objective lens and a convex spherical lens integrated with a quarter-wave plate 212. At the time of bonding, if alignment marks are provided to each other so that alignment can be performed accurately, positioning can be performed accurately.

Finally, a fine movement actuator is manufactured in the following procedure. The fine movement actuator is an electrostatic fine movement actuator, and is formed on a Si substrate by a semiconductor manufacturing process such as photolithography and wet / dry etching.

That is, as shown in FIG. 22, a Si substrate 214 is used as a swing arm, and the substrate 214 is finely processed to produce a focusing fine movement actuator 215 and a tracking fine movement actuator 216 as fine movement actuators. The manufactured fine movement actuator 215 for focusing and fine movement actuator 216 for tracking are mounted on the substrate 20 as shown in FIG.
The polarization hologram 213 on the substrate 0 is disposed at a portion through which light does not pass, or a through portion through which light passes is formed on the Si substrate 214, and the through portion is disposed at a portion through which the light passes through the polarization hologram 213, and polarization is performed. The connection on the hologram 213 completes the creation of the optical pickup optical system 217. The connection of the Si substrate 214 on which the focusing fine movement actuator 215 and the tracking fine movement actuator 216 are formed onto the polarization hologram 213 may be performed by bonding, or the polarization hologram 213 is made of glass, and glass and Si May be performed by anodic bonding. Further, the Si substrate 2 on which the fine movement actuator 215 for focusing and the fine movement actuator 216 for tracking on the polarization hologram 213 are formed.
14 is aligned with the polarization hologram 213 and 1 /
As in the case of the alignment with the four-wavelength plate 212, the alignment can be accurately performed by providing the alignment mark.

It should be noted that, in practice, since a large number of elements are formed in an array on the substrate 200, they are cut into individual elements.

As described above, the invention made by the inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to the above, and various modifications can be made without departing from the gist of the invention. It goes without saying that it is possible.

[0139]

According to the information recording / reproducing apparatus of the first aspect of the present invention, the light beam emitted from the light source is irradiated through the transparent protective layer of the information recording medium by the objective lens provided at the tip of the swing arm. When recording and reproducing information on the recording layer, a substantially hemispherical convex spherical lens is provided between the objective lens and the transparent protective layer of the information recording medium, and the distance between the convex spherical lens and the transparent protective layer is fixed. Focusing operation and tracking operation for moving the optical axis of the objective lens and convex spherical lens along the information track provided on the information recording medium are finely performed by the fine movement actuator, and the focusing operation and tracking operation are performed. Is roughly performed by the coarse actuator, so that high-density recording / reproduction can be performed, and the light use efficiency can be improved. It may correspond to the precision of the movement amount by density and NA of the recording medium.

According to the information recording / reproducing apparatus according to the second aspect of the present invention, since the objective lens and the convex spherical lens are formed as an integrated optical element, it is not necessary to align the two lenses. At the same time, the device can be made small and thin.

According to the information recording / reproducing apparatus according to the third aspect of the present invention, the optical path separating means for separating the optical path and the light beam are focused on the objective lens or the optical element in which the objective lens and the convex spherical lens are integrated. Since at least one of the light condensing means is integrally provided, the alignment can be omitted, and the device can be reduced in size and thickness.

According to the information recording / reproducing apparatus of the fourth aspect, the surface of the convex spherical lens through which light on the information recording medium side passes is formed as a concave surface or a convex surface, and the peripheral portion of the surface through which the light passes is formed. Is formed on a flat or curved surface, so that even if the convex spherical lens side and the information recording medium come into contact with each other due to the mechanical characteristics of the information recording medium itself or an external impact, the convex spherical lens itself may be damaged. It is possible to suppress the impact caused by these collisions, and to protect the entire mechanism including the fine actuator and the coarse actuator.

According to the information recording / reproducing apparatus of the present invention, the projection of the convex spherical lens on the information recording medium side where the light does not pass is higher than the projection of the light passing side on the information recording medium side. Is formed, and the projection has an impact absorbing function. Therefore, even if the convex spherical lens side and the information recording medium come into contact with each other due to mechanical characteristics of the information recording medium itself or an external impact, the convex spherical lens itself is formed. Can be suppressed, and the impact caused by these collisions can be reduced to protect the entire mechanism including the fine actuator and the coarse actuator.

According to the information recording / reproducing apparatus of the present invention, since at least one of the objective lens and the convex spherical lens is aspherical, the convexity of the information recording medium itself due to the mechanical characteristics of the information recording medium itself or an external impact. Even if the lens side contacts the information recording medium, it is possible to prevent the convex spherical lens itself from being damaged.

According to the information recording / reproducing apparatus of the present invention, since the diameters of the objective lens and the convex spherical lens are smaller than 1 mm, the objective lens and the convex spherical lens are formed by a lens processing method using a semiconductor. A lens can be made, and the optical system can be made small and thin, and inexpensive.

According to the information recording / reproducing apparatus of the present invention, the coarse motion actuator performs a coarse motion by rotating the swing arm, and the fine motion actuator performs a rotary motion to reduce the skew of the information track. It operates along the information track while correcting it, enabling more accurate tracking, suppressing signal errors, and increasing the amount of movement due to the high density and high NA of the optical information recording medium. More appropriate measures can be taken by improving the accuracy.

According to the information recording / reproducing apparatus of the ninth aspect of the present invention, as the fine movement actuator, an electrostatic type, a piezoelectric type,
Since an electromagnetic induction type or ultrasonic type actuator is used, the information recording / reproducing apparatus can be made cheaper and smaller.

According to the information recording / reproducing apparatus of the present invention, since the distance between the convex spherical lens and the information recording medium is set to several tens μm or more, it is easy to put the information recording medium into and out of the information recording / reproducing apparatus. In addition to being able to carry out easily, signal errors due to dust and dirt can be suppressed.

According to the method of manufacturing an optical element for an information recording / reproducing apparatus according to the present invention, it is preferable that the optical recording medium be manufactured in the following manner.
Since the micro-movement actuator and the optical components such as the objective lens and the convex spherical lens described in No. 0 are manufactured by using the photolithography and the etching technology, it is easy to manufacture a small optical element and to precisely align the lens groups. In addition to this, a large number of optical elements can be manufactured at once at a low cost.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of an information recording / reproducing apparatus to which an information recording / reproducing apparatus according to a first embodiment of the present invention is applied.

FIG. 2 is an enlarged front view of an optical pickup part of the information recording / reproducing apparatus of FIG.

FIG. 3 is a bottom view of the optical pickup of FIG. 2;

FIG. 4 is an enlarged front view of an optical pickup part of the information recording / reproducing apparatus to which the second embodiment of the information recording / reproducing apparatus of the present invention is applied.

FIG. 5 is a bottom view of the optical pickup of FIG. 4;

FIG. 6 is an enlarged front view showing another example of the optical pickup of FIG. 4;

FIG. 7 is an enlarged front view of an optical pickup portion of an information recording / reproducing apparatus to which a third embodiment of the information recording / reproducing apparatus of the present invention is applied.

FIG. 8 is a bottom view of the optical pickup of FIG. 7;

FIG. 9 is an enlarged front view of an optical pickup part of an information recording / reproducing apparatus to which an information recording / reproducing apparatus according to a fourth embodiment of the present invention is applied.

FIG. 10 is a bottom view of the optical pickup of FIG. 9;

FIG. 11 is a bottom view showing the operation state of the actuator of the optical pickup of FIG. 9;

FIG. 12 is a front view of a state in which a photosensitive material is applied on a substrate as a procedure of a method of manufacturing an optical pickup optical system to which the fifth embodiment of the method of manufacturing an optical element for an information recording / reproducing apparatus according to the present invention is applied. FIG.

FIG. 13 is a front view showing a state where a concave portion having the same shape as an objective lens is formed in the photosensitive material of FIG. 12;

FIG. 14 is a front view showing a state where a concave lens shape portion is formed by etching the substrate of FIG. 13;

FIG. 15 is a front view showing a state where an objective lens material is applied on the substrate of FIG. 14;

FIG. 16 is a front view of the substrate in a state where an objective lens is formed by removing an objective lens material other than the concave lens shape portion of FIG. 15;

17 is a front view of a state in which a photosensitive material is applied to the surface of the substrate of FIG. 16 opposite to the objective lens, and a concave portion having the same shape as the convex spherical lens is formed in the photosensitive material.

FIG. 18 is a front view showing a state where a concave lens shape portion is formed by etching the substrate of FIG. 17;

FIG. 19 is a front view showing a state in which a convex spherical lens is formed by embedding a convex spherical lens material in the concave lens shape portion of FIG. 18 and then a projection is formed to form a protective layer.

20 is a front view of a state in which a quarter-wave plate is formed on the surface of the substrate of FIG. 19 on the objective lens side.

FIG. 21 is a front view of a state where a polarization hologram is formed on a 波長 wavelength plate of the substrate of FIG. 20;

FIG. 22 is a front view showing a state in which a fine movement actuator is connected on the polarization hologram of the substrate of FIG. 21;

FIG. 23 is a schematic configuration diagram of a conventional optical pickup.

FIG. 24 is a schematic configuration diagram of a conventional optical element in which a solid immersion lens is provided between an objective lens and a recording medium.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 100 Information recording / reproducing apparatus 101 Coarse movement actuator 102 Swing arm 103 Pickup optical system 104 Fine movement actuator 105 Information recording medium 110 Polarization beam splitter 111 1/4
Wave plate 112 Objective lens 113 Convex spherical lens 114 Spacer 120 Information recording / reproducing device 121 Pickup optical system 122 Objective lens 123 Convex spherical lens 124 Substrate 125 Polarization hologram 126 Mirror 130 Convex spherical lens 140 Information recording / reproducing device 141 Pickup optical system 142 Objective lens 143 convex spherical lens 144 substrate 145 波長 wavelength plate 146 polarization hologram 147 mirror 148 projection 149 protective layer 150 information recording / reproducing device 151 pickup optical system 152 objective lens 153 convex spherical lens 154 substrate 155 focusing fine movement actuator 156 ４ wavelength Plate 157 Polarization hologram 158 Tracking micro-movement actuator 159 Substrate 160 Mirror 161 Projection 162 Protective layer 200 Substrate 2 DESCRIPTION OF SYMBOLS 1 Photosensitive material 202 Concave part 203 Concave lens shape part 204 Sputtered film 205 Objective lens 206 Photosensitive material 207 Concave part 208 Concave lens shape part 209 Convex spherical lens 210 Projection 211 Protective layer 212 Quarter wave plate 213 Polarization hologram 214 Si substrate 215 Focusing Fine actuator 216 Fine actuator for tracking 217 Optical pickup optical system

Claims (11)

[Claims] An information recording / reproducing device for irradiating a light beam emitted from a light source through a transparent protective layer of an information recording medium with an objective lens provided at a tip of a swing arm to record / reproduce information on / from the recording layer. In the apparatus, a substantially hemispherical convex spherical lens provided between the objective lens and the transparent protective layer of the information recording medium, and a focusing operation for keeping a distance between the convex spherical lens and the transparent protective layer constant A fine movement actuator that finely performs both operations of a tracking operation of moving the optical axes of the objective lens and the convex spherical lens along an information track provided on the information recording medium; and performing the focusing operation and the tracking operation. An information recording / reproducing apparatus, comprising: a coarse motion actuator for performing a rough motion. 2. An information recording / reproducing apparatus according to claim 1, wherein said objective lens and said convex spherical lens are formed as an integral optical element. 3. An information recording / reproducing apparatus, comprising: an optical path separating means for separating the optical path and the light beam to the objective lens or the optical element in which the objective lens and the convex spherical lens are integrated. 3. An information recording / reproducing apparatus according to claim 1, wherein at least one of said light collecting means is provided integrally. 4. A surface of the convex spherical lens through which light on the information recording medium side passes is formed as a concave surface or a convex surface, and a peripheral portion of the surface through which the light passes is formed as a flat surface or a curved surface. 4. The method according to claim 1, wherein
An information recording / reproducing device according to any one of the above. 5. The convex spherical lens has a projection formed on a portion of the information recording medium through which light does not pass, the projection protruding higher toward the information recording medium than a portion through which light passes.
The information recording / reproducing apparatus according to any one of claims 1 to 4, wherein the projection has a shock absorbing function. 6. The objective lens and the convex spherical lens according to claim 1, wherein at least one surface is an aspheric surface.
An information recording / reproducing apparatus according to any one of claims 1 to 5. 7. The information recording / reproducing apparatus according to claim 1, wherein the objective lens and the convex spherical lens have a lens diameter smaller than 1 mm. 8. The coarse motion actuator performs the coarse motion by rotating the swing arm, and the fine motion actuator rotates along the information track while correcting the skew of the information track. The information recording / reproducing apparatus according to any one of claims 1 to 7, which operates. 9. The information recording / reproducing apparatus according to claim 1, wherein said fine movement actuator is an electrostatic type, a piezoelectric type, an electromagnetic induction type, or an ultrasonic type actuator. apparatus. 10. The information according to claim 1, wherein in the information recording / reproducing apparatus, an interval between the convex spherical lens and the information recording medium is several tens μm or more. Recording and playback device. 11. An information recording apparatus according to claim 1, wherein said fine movement actuator and optical parts such as said objective lens and said convex spherical lens are manufactured by using photolithography and etching techniques. A method for manufacturing an optical element for a reproducing apparatus.