JP3406338B2 - Disk recording medium manufacturing equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention irradiates a resist film formed on a circular substrate with a light beam which is modulated based on recording data to form a data pattern based on the recording data input to an optical modulator. The present invention relates to a disk-shaped recording medium manufacturing apparatus for manufacturing a master of a disk-shaped recording medium by exposing and recording.

[0002]

2. Description of the Related Art Recently, an optical recording device using laser light, that is, a so-called laser cutting device is generally used in manufacturing a master of an optical recording medium (optical disk, magneto-optical disk, etc.).

A conventional laser cutting device will be described, for example, mainly for producing a master of an optical disk. For example, as shown in FIG. 13, a gas laser light source 51 using a gas as an amplifying medium and a laser emitted from the gas laser light source 51. A mirror 52 that guides the light L to an optical system in the subsequent stage, an optical modulator that modulates the intensity of the laser light L guided through the mirror 52 according to a recording signal, and an intensity modulator that modulates the intensity of the laser light L. The mirror 5 that guides the laser light L to the objective lens 54
5 and 56. The objective lens 54 and the mirror 56 are arranged on the photoresist film 58 formed on the circular substrate 57 so as to face each other at a predetermined interval, and are moved in the radial direction of the circular substrate 57 by a known moving mechanism.

When an acousto-optical modulator (Acousto Optic Modulator; hereinafter simply referred to as AOM) 60 is used as the optical modulator, as shown in FIG.
The beam reduction lens 61 is arranged in front of the AOM 60.
A beam expanding lens 62 is arranged in the subsequent stage of 60.

A laser beam L of a parallel light flux emitted from a laser light source 51 is reduced in beam diameter by a beam reduction lens 61 and is incident on an AOM 60.
At 60, the light intensity is modulated according to the supplied ultrasonic wave (which is modulated based on the recording signal). The laser beam L intensity-modulated by the AOM 60 has its beam diameter restored by the beam expanding lens 62 in the subsequent stage to become parallel light, and thereafter is reflected on the photoresist film 58 via the mirrors 55 and 56 and the objective lens 54. Is irradiated.

The circular substrate is rotatively driven by a CAV system, for example, by a rotary drive system (not shown), and the photoresist film 58 is irradiated with the laser light L whose intensity is modulated based on a recording signal. A recording pattern corresponding to the recording signal is drawn on the resist film 58 along the concentric circles of the circular substrate 57 or along the spiral shape.

That is, the photoresist film 58 is exposed along the drawn recording pattern, and the exposed portion is dissolved by the developing solution in the next developing step. Therefore, in the subsequent developing process, the exposed portion is removed and a mask made of the photoresist film 58 is formed. After that, electroless plating, nickel plating, a cleaning process, and the like are performed, so that a master for an optical disk is manufactured.

[0008]

By the way, the size of pits and grooves of an optical disc varies depending on its specifications (for example, size and purpose). Conventionally, regarding the pit, for example, in order to set its shape, the beam diameter of the laser light L is changed by a beam expander composed of a beam reduction lens 61 and a beam expansion lens 62, and the mirrors 55 and 56. By changing the effective pupil diameter with respect to the entrance pupil diameter of the objective lens 54 by the lens element 63 installed between them to change the NA on the exit side of the objective lens, the pit shape according to various specifications can be obtained. I'm trying to make a decision.

This is also realized by changing the focal length of the lens element 63. That is, as shown in FIG. 14, the lens element 63 condenses the laser light L at the optimum condensing position Pf on the optical characteristics of the objective lens 54,
The beam shape at the objective lens condensing surface PB is determined by the beam shape due to the condensing ability and the change in the area ratio that fills the pupil surface of the objective lens 54 after passing the condensing position Pf.

In practice, the beam reduction lens 61, the beam expansion lens 62, and the lens element 63 themselves are changed / replaced according to various specifications, thereby realizing a pit shape, that is, a light beam diameter according to various specifications. I am trying.

However, it is not easy to change or replace the beam reducing lens 61, the beam expanding lens 62, and the lens element 63, which are individual optical elements, and it is necessary to reset the entire optical system from the initial state each time it is changed. However, there is an inconvenience that the fine adjustment accompanying this resetting becomes complicated and very troublesome.

Further, although the signal characteristics (pit modulation degree, groove condition, etc.) differ according to various specifications, in order to optimize the signal characteristics, the above-mentioned resetting is performed several times while setting the conditions. There is the hassle of having to do it. Moreover, there is a limit to the range in which the pit shape can be changed by changing or replacing the single optical element, that is, the degree of freedom with respect to the pit shape of the single optical element is limited. The current situation is that

As described above, in the conventional laser cutting apparatus, much time is spent for resetting the optical system and optimizing the conditions in accordance with various specifications of the optical disc, so that an efficient optical disc The master cannot be made.

This is because, as the current technology, a setting method using a single optical element is used to change the beam shape of the laser beam L. In order to change the beam shape, the single optical element is used. This is because element replacement and setting adjustment are required each time. In addition, it is virtually impossible to arbitrarily select the focal length of a single optical element, and there is a problem in that optimization of signal characteristics is difficult.

The present invention has been made in view of the above problems, and an object of the present invention is to arbitrarily and easily change the luminous flux diameter of a light beam according to various specifications of a disk-shaped recording medium. It is therefore an object of the present invention to provide a disk-shaped recording medium manufacturing apparatus capable of easily manufacturing a master of a disk-shaped recording medium according to various specifications.

Further, according to the present invention, the optimization of signal characteristics according to various specifications and the setting of conditions necessary for manufacturing can be performed very easily, and the disc-shaped recording medium can be efficiently developed. An object is to provide an apparatus for manufacturing a disc-shaped recording medium.

[0017]

The present invention proposed to achieve the above object is to irradiate a resist film formed on a circular substrate with a light beam modulated based on recording data. In a disk-shaped recording medium manufacturing apparatus for producing a master of a disk-shaped recording medium by exposing and recording a data pattern based on the recording data, an optical system for modulating the light beam with a recording signal, and the optical system A beam diameter conversion optical system that changes the diameter of the beam, and a converging lens element that changes the focal length of the laser light incident from the polarization beam splitter are provided. Here, the optical system that modulates the light beam with the recording signal includes a beam reducing lens that narrows the beam of the laser light through a half mirror, and a beam reducing lens based on the ultrasonic wave that is modulated with the recording signal. It is composed of an acousto-optic modulator that intensity-modulates the laser light, and a beam expansion lens that converts the intensity-modulated laser light from the acousto-optic modulator into a parallel light beam and restores the original beam diameter.

In this case, the light beam diameter converting optical system is constructed by a lens group in which at least a first converging lens, a diverging lens and a second converging lens are arranged in this order along the traveling direction of the light beam. , The change in the luminous flux diameter of the light beam incident on this lens group between the first distance between the first converging lens and the diverging lens and the second distance between the diverging lens and the second converging lens. The structure is made variable according to.

In this case, the beam diameter converting optical system is composed of a lens group in which at least a first converging lens, a diverging lens and a second converging lens are arranged in this order along the traveling direction of the light beam. , The beam diameter of the light beam incident on this lens group is transferred to the fixed first converging lens.
A structure for varying in response to changes in a second distance between the rotatably and has been first distance and the diverging lens movable and have been the second converging lens between the diverging lens.

Alternatively, the light beam diameter converting optical system is installed immediately before the objective lens in which the light beam is a parallel light beam, and at least a first converging lens and a diverging lens are provided along the traveling direction of the light beam. The first converging lens is composed of a lens group in which a lens and a second converging lens are arranged in this order, and the luminous flux diameter of a light beam incident on the lens group is movable. A first distance between the divergent lenses that is movable and a second distance fixed to the divergent lenses.
Variable according to the change of the second distance between the converging lenses of
The structure is such that the same focal point has different focal lengths.

[0021]

In the disk-shaped recording medium manufacturing apparatus according to the present invention, the diameter of the light beam is changed by the light beam diameter converting optical system and the resist film is irradiated with the light beam. Therefore, by setting the variable amount of the beam diameter by the light beam diameter conversion optical system according to various specifications, it is possible to easily manufacture a master of a disk-shaped recording medium according to various specifications.

Specifically, regarding one invention,
Since the light beam diameter converting optical system is configured by the lens group in which at least the first converging lens, the diverging lens and the second converging lens are arranged in this order along the traveling direction of the light beam, Between the converging and diverging lenses of
And the second distance between the diverging lens and the second converging lens based on various specifications, the light beam diameter of the light beam incident on the lens group changes according to various specifications. .

Further, according to another invention, the light beam diameter converting optical system is installed in the non-parallel light beam immediately after the light beam in the optical modulator for modulating the light beam based on the recording data, and the light beam diameter conversion is performed. An optical system is arranged at the rear of the second converging lens, and a lens group in which at least a first converging lens, a diverging lens and a second converging lens are arranged in this order along the traveling direction of the light beam. Since it is composed of a shifter for optical axis correction, the first distance between the first converging lens and the diverging lens and the second distance between the diverging lens and the second converging lens can be set to various specifications. By changing based on this, the luminous flux diameter of the light beam incident on the lens group changes according to various specifications. In particular, the optical axis of the light beam that has passed through the second converging lens is displaced, but the optical axis is corrected by the shifter for correcting the optical axis in the subsequent stage. No deviation of the optical axis occurs in the emitted light beam.

Further, regarding still another invention, the light beam diameter converting optical system is installed immediately before the objective lens in which the light beam is a parallel light beam, and the light beam diameter converting optical system is
Since the lens group is composed of at least a first converging lens, a diverging lens, and a second converging lens arranged in this order along the traveling direction of the light beam, the light beam incident on this lens group Is changed in accordance with a change in a first distance between the first converging lens and the diverging lens and a second distance between the diverging lens and the second converging lens, and further the same focus is achieved. Focusing with different focal lengths is performed. As a result, the light beam diameter of the light beam incident on the lens group changes according to various specifications.

[0025]

EXAMPLE An example in which the disk-shaped recording medium manufacturing apparatus according to the present invention is applied to a laser cutting apparatus used in manufacturing an optical disk master (hereinafter, simply referred to as a laser cutting apparatus according to the example) Some of these will be described with reference to FIGS.

First, in the laser cutting apparatus according to the first embodiment, as shown in FIG. 1, a gas laser light source 1 using a gas as an amplification medium and a laser light L emitted from the gas laser light source 1 are divided into two light beams. Half mirror H divided into components
M, an optical system for drawing a groove (hereinafter referred to as a groove optical system) G on which one light component L1 reflected by the half mirror HM is incident, and the other light component transmitted through the half mirror HM. Optical system for pit drawing in which L2 is incident through the mirror M1 (hereinafter referred to as pit optical system)
P, a polarization beam splitter PBS from which the laser beams L1 and L2 from the groove optical system G and the pit optical system P are respectively incident to guide the laser beams L1 and L2 to one optical path, and the polarization beam splitter PBS from this polarization beam splitter PBS. Mirror M for guiding laser light (L1, L2) to objective lens OB
It consists of 2 and.

Two mirrors M3 and M4 for guiding the laser beam L1 from the groove optical system G to the polarizing beam splitter PBS are arranged between the groove optical system G and the polarizing beam splitter PBS, and The laser beam L2 from the pit optical system P is polarized beam splitter P between the pit optical system P and the polarization beam splitter PBS.
One mirror M5 leading to the BS is arranged.

The objective lens OB and the mirror M2 are arranged on the photoresist film 3 formed on the circular substrate 2 so as to face each other with a predetermined gap, and are moved in the radial direction of the circular substrate 2 by a known moving mechanism. . Here, when the photosensitive material of the photoresist film 3 is a positive type, the laser light L having an oscillation wavelength of 458 nm for Ar laser and 442 nm for He-Cd laser is selected. Incidentally, recently, a Kr laser having an oscillation wavelength near 400 nm may also be used. Also, these gas lasers
It is emitted as linearly polarized laser light L through the Brewster window.

The groove optical system G is based on a beam reduction lens GB1 for narrowing the beam diameter of the laser light (parallel light flux) L1 reflected by the half mirror HM, and an ultrasonic wave modulated by the groove recording signal. , An acousto-optical modulator (Acousto Optic Modulator) for intensity-modulating the laser beam L1 from the beam reduction lens GB1;
GA) and a beam expanding lens GB2 for converting the intensity-modulated laser beam (diffused beam) from the AOM (GA) into a parallel beam and returning it to the original beam diameter.

Further, the pit optical system P has a mirror M1.
The beam reducing lens PB1 for narrowing the beam diameter of the laser beam (parallel light beam) L2 reflected by the beam reducing lens PB1 is based on the ultrasonic wave modulated by the pit recording signal.
AOM (PA) for intensity-modulating the laser beam L2 from
It is composed of a beam expanding lens PB2 for converting the intensity-modulated laser beam (diffused beam) from the AOM (PA) into a parallel beam and returning it to the original beam diameter.

Further, a converging lens element LE for varying the focal length of the laser beams (L1, L2) incident from the polarization beam splitter PBS is arranged between the polarization beam splitter PBS and the mirror M2. That is, this converging lens element LE, as shown in FIG.
A laser beam (L1, L1,
L2) is condensed, and the beam shape at the objective lens condensing surface PB is determined by the beam shape due to the condensing ability and the change in the area ratio that fills the pupil surface of the objective lens OB after passing the condensing position Pf. It is a thing.

AOM (GA, PA) is, for example, TeO ₂
It is composed of a crystal and uses the phase diffraction grating due to the change in the refractive index generated in the crystal by the supply of ultrasonic waves from the ultrasonic wave generation circuit, and uses the first-order diffracted light of the Bragg diffraction for signal recording. . The intensity of the diffracted light is determined by the ultrasonic power, and the diffraction direction is determined by the carrier frequency.

In the laser cutting apparatus according to the first embodiment, the beam diameter converting optical systems GPO and PPO are respectively provided between the groove optical system G and the mirror M3 and between the pit optical system P and the mirror M5. Are arranged.

The respective light beam diameter conversion optical systems GPO and PPO are
It is composed of 3 elements in 3 groups. For example, as shown in FIG.
The first converging lens La, the diverging lens Lb, and the second converging lens Lc are arranged along the traveling direction of the laser light L1 (L2).
And the luminous flux diameter φ of the laser light L1 (L2) that is made incident on this lens group 11.
D is the first between the first converging lens La and the diverging lens Lb.
Distance S1, the diverging lens Lb and the second converging lens Lc
The structure is variable according to the change of the second distance S2 between them. That is, the optical system is capable of arbitrarily changing the effective NA on the exit side of the objective lens.

First, the laser beam (parallel light flux) L1 (L2) emitted from the beam expanding lens GB2 (PB2) is
It is converted into a convergent light beam by the first converging lens La and is incident on the diverging lens Lb at the next stage. The convergent light beam incident on the diverging lens Lb has its light beam diameter φD reduced according to the first distance S1. The laser light L1 (L2) that has entered the diverging lens Lb is converted into a divergent light beam, and then enters the second converging lens Lc in the next stage and converted into a parallel light beam. That is, the laser beam L1 (L2) emitted from the second converging lens Lc is converted into a parallel light beam having the same diameter as the light beam diameter when entering the second converging lens Lc. In this case, the first converging lens La is fixed,
The first and second distances S1 and S2 are changed by moving the diverging lens Lb and the second converging lens Lc.

Diameter φ of the parallel light flux in this lens group 11
The rate of change (magnification) of D is shown in the characteristic diagrams of FIGS. 4 and 5 and Tables 1 to 7. For example, as shown in FIG. 3, the diameter of the emitted parallel light flux is 0.
8 times, that is, when the magnification is 0.8, the first distance S1
Is 27.36140 mm, and the second distance S2 is 53.
55102 mm. When the magnification is 1.0, the first distance S1 is 25.35423 mm and the second distance S1 is
The distance S2 is set to 71.39696 mm. When the magnification is 1.6, the first distance S1 is 19.332.
70 mm and the second distance S2 is 98.16587 mm
To When the magnification is 2.1, the first distance S1 is 14.31477 mm and the second distance S2 is 1.
It is set to 08.788846 mm.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

[0041]

[Table 5]

[0042]

[Table 6]

[0043]

[Table 7]

The lens group 11 has an optical design for suppressing the occurrence of the wavefront aberration of the laser beams L1 and L2 at each magnification. Below, lens group 1
A specific configuration example of the first converging lens La, the diverging lens Lb, and the second converging lens Lc that configure No. 1 will be described.

As shown in FIG. 6A, the first converging lens La has an entrance side curvature radius Rai of 79.594 mm, an exit side curvature radius Rao of 57.591 mm, and a diameter φMa of 2.
The convex lens has a diameter of 0 mm (effective pupil diameter φda = 15 mm) and a maximum thickness ta of 3.0 mm, and its attributes are as follows.

NR: R1 = 3 R2 = 3 ・ AS: R1 = 0.5 R2 = 0.5 ・ Eccentricity δ = 30 "・ Material BK7 (nd = 1.51680) ・ MgF ₂ coating (λ = 441) R at 0.6 nm
<0.2%) f = 63.99 (λ = 441.6 nm)

As shown in FIG. 6B, the diverging lens Lb has an entrance side curvature radius Rbi of 40.561 mm, an exit side curvature radius Rbo of 30.282 mm, and a diameter φMb of 20 mm.
(Effective pupil diameter φdb = 15 mm), minimum thickness tb is 2.0
It is a concave lens of mm, and its attributes are as follows.

NR: R1 = 3 R2 = 3 AS: R1 = 0.5 R2 = 0.5 eccentricity δ = 30 ″ Material F2 (nd = 1.62004) MgF ₂ coating (λ = 441) R at 0.6 nm
<0.2%) f = −26.76 (λ = 441.6 nm)

As shown in FIG. 6C, the second converging lens Lc has an incident side radius of curvature Rci of 287.826 mm,
Radius of curvature Rco is 130.036 mm, diameter φMc
Is 20 mm (effective pupil diameter φdc = 15 mm), maximum thickness t
c is a 3.0 mm convex lens, and its attributes are as follows.

NR: R1 = 3 R2 = 3 AS: R1 = 0.5 R2 = 0.5 eccentricity δ = 30 ″ Material BK7 (nd = 1.51680) MgF ₂ coating (λ = 441) R at 0.6 nm
<0.2%) f = 170.67 (λ = 441.6 nm)

As described above, the beam diameter of the laser beam (parallel beam) emitted from the second converging lens Lc is continuously expanded as the magnification of the lens group 11 is increased, and the beam shape is, for example, as shown in FIG. As shown in FIG. 7A, the shape becomes wide, and the ratio of filling the pupil plane OBa of the objective lens OB continuously increases (see FIG. 7B). With the increase of the ratio, the condensing ability by the objective lens OB is improved, and the shape of the condensed beam with which the photoresist film 3 is irradiated is continuously narrowed (see FIG. 7C).

Therefore, by appropriately selecting the first distance S1 and the second distance S2 in the lens group 11 according to various specifications, it is possible to obtain pit shapes and groove shapes according to various specifications. That is, as shown in FIG. 8, normally, only the signal characteristic on one change curve can be set as shown by the curve a, but in the first embodiment, the range shown by the curve a and the curve b is set. It is possible to freely set the signal characteristics within (indicated by diagonal lines), and it is possible to easily perform optimization study of the signal characteristics according to various specifications.

As described above, the AOM (GA) in the groove optical system G and the AOM in the pit optical system P are set.
The laser beams L1 and L2 each intensity-modulated by (PA) are converted into light beam diameters in accordance with the specifications in the light beam diameter conversion optical systems GPO and PPO in the subsequent stage, and are incident on the polarization beam splitter PBS in the subsequent stage. become. The laser light L1 from the groove optical system G is reflected by the polarization plane of the polarization beam splitter PBS and guided to the objective lens OB side, and the laser light L2 from the pit optical system P changes the polarization plane of the polarization beam splitter PBS. It is transmitted as it is and guided to the objective lens OB side. Each laser beam L1 and L2
Is finally collected by this objective lens OB,
The photoresist film 3 is irradiated.

The circular substrate 2 is rotationally controlled in one direction by, for example, a CAV method by a spindle motor (not shown), and the mirror M2 and the objective lens OB are moved in the radial direction of the circular substrate 2 by a known moving mechanism. Therefore, for example, by supplying the groove recording signal and the pit recording signal for the optical disk to the input terminals of the ultrasonic wave generation circuits in each AOM (GA) and (PA), the photoresist film 3 on the circular substrate 2 is supplied with the groove recording signal and the pit recording signal. A recording pattern based on the signal is drawn along the concentric circles of the circular substrate 2 or along the spiral shape.

The photoresist film 3 is exposed along the drawn recording pattern, and the exposed portion is dissolved by the developing solution in the next developing step. Therefore, in the subsequent developing process, the exposed portion is removed and a mask made of the photoresist film 3 is formed. After that, electroless plating, nickel plating, a cleaning step, and the like are performed on the basis of a normal master manufacturing process to manufacture a master for an optical disc.

As described above, in the laser cutting apparatus according to the first embodiment, the light beam diameter conversion optical system GPO is used.
Since the diameters of the laser beams L1 and L2 are changed by PPO and PPO and irradiated on the photoresist film 3, the variable amount of the beam diameter by the light beam diameter conversion optical systems GPO and PPO should be set according to various specifications. Thus, it is possible to easily manufacture a master disc of an optical disc according to various specifications.

That is, in the above example, the laser beam L1
Along the traveling direction of (L2), the first converging lens La,
In the lens group 11 arranged in order of the diverging lens Lb and the second converging lens Lc, the light beam diameter conversion optical system GPO (PP
O), the first distance S1 between the first converging lens La and the diverging lens Lb and the diverging lens Lb.
By changing the second distance S2 between the second converging lens Lc and the second converging lens Lc based on various specifications, the luminous flux diameter φD of the laser light L1 (L2) incident on the lens group 11 changes according to various specifications. Becomes

Therefore, it is possible to easily manufacture a master disk of an optical disk according to various specifications, and it is possible to very easily perform optimization of signal characteristics according to various specifications and setting of conditions necessary for manufacturing. Therefore, the optical disc can be efficiently developed.

Here, as a modification of the laser cutting apparatus according to the first embodiment, as shown in FIG.
The laser beams L1 and L2 whose light intensity is modulated by the OM (GA) and (PA) do not pass through the beam expanding lenses GB2 and PB2, respectively, but the light beam diameter converting optical systems GPO and PPO directly.
You may make it inject into. In this case, AOM (G
Since the light diffracted by A) and (PA) is used as an exposure beam, as shown in FIG.
The optical axis of the laser beam L1 (L2) emitted from PO (PPO) is slightly deviated. Therefore, for example, the shift of the optical axis can be corrected by disposing the shifter S that corrects the shift of the optical axis in the subsequent stage of the light beam diameter conversion optical system GPO (PPO).

According to this modification, the beam expanding lens G
Since B2 and PB2 can be omitted, the structure of the entire optical system of the laser cutting device can be simplified.

Next, the laser cutting apparatus according to the second embodiment will be sequentially described with reference to FIGS. The same reference numerals are given to those corresponding to those in FIGS.

As shown in FIGS. 10 and 11, the laser cutting apparatus according to the second embodiment has substantially the same structure as that of the first embodiment, but is arranged between the polarization beam splitter PBS and the mirror M2. The optical component to be converted is not the convergent lens element LE but the light beam diameter conversion optical system ZP.
O is different.

A light beam diameter converting optical system Z arranged at this position
As the PO, it is necessary to focus the laser beams L1 and L2 emitted from the optical system ZPO at the focusing position Pf even when the zoom magnification changes. That is, a zoom function that changes the focal length f without changing the focal position Pf is required. Further, an optical system in which wavefront aberration is favorably corrected for all magnifications is required.

Therefore, in the second embodiment, as the light beam diameter converting optical system ZPO satisfying the above conditions, as shown in FIG. 12, along the traveling direction of the laser beam L1 (L2),
The first converging lens La, the diverging lens Lb, and the second converging lens Lc are arranged in this order in the lens group 12,
The light beam diameter φD of the laser light L1 (L2) incident on the lens group 12 is converted to the first converging lens La and the diverging lens Lb.
A structure for varying the first distance S1 between them and the second distance S2 between the diverging lens Lb and the second converging lens Lc to condense different focal lengths f on the same focal point Pf. I am trying. That is, by fixing the second converging lens Lc and moving the first converging lens La and the diverging lens Lb, the first and second distances S1 and S2 are obtained.
Is to be changed.

From this, the polarization beam splitter PB
The laser light (parallel light flux) L1 (L2) from S is
It is converted into a convergent light beam by the first converging lens La and is incident on the diverging lens Lb at the next stage. The convergent light flux incident on the diverging lens Lb has its diameter reduced according to the first distance S1. The laser beam L1 (L2) incident on the diverging lens Lb is converted into a divergent light beam, is then incident on the second converging lens Lc in the next stage, and is converted into a convergent light beam. In this case, since the second converging lens Lc is fixed, the incident diffused light flux is converted into a convergent light flux and is condensed at the optimum condensing position Pf on the optical characteristics of the objective lens OB. Become.

FIG. 12 shows that the focal length f is 80 mm.
(See FIG. 12A), 100 mm (see FIG. 12B), 12
The figures show the cases of 0 mm (see FIG. 12C) and 140 mm (see FIG. 12D). When the focal length f is shortened, the focused beam shape at the optimum focusing position Pf becomes narrower, and the objective lens OB The diameter of the light beam that fills the pupil surface increases. Along with that, finally the objective lens focusing surface PB
The shape of the focused beam at becomes narrower.

Therefore, in the light beam diameter converting optical system ZPO, the light collecting ability and the light collecting position Pf at the optimum light collecting position Pf.
The amount of light flux that fills the pupil plane of the objective lens OB after passing can be changed arbitrarily and continuously to freely set the beam shape on the objective lens condensing surface PB.

As described above, also in the laser cutting apparatus according to the second embodiment, the first converging lens La, the diverging lens Lb and the second converging lens Lc are arranged along the traveling direction of the laser beam L1 (L2). Since the lens group 12 arranged in this order constitutes the light beam diameter conversion optical system ZPO, it is the first lens between the first converging lens La and the diverging lens Lb.
Distance S1, the diverging lens Lb and the second converging lens Lc
By changing the second distance S2 between them based on various specifications, the laser light L1 (L2
) The light flux diameter will change according to various specifications.

Therefore, as in the above-described embodiment, the diameter of the laser beam L1 (L2) is changed by the light beam diameter conversion optical system ZPO and the photoresist film 3 is irradiated with the light beam diameter conversion optical system ZPO. By setting the variable amount of the beam diameter according to various specifications, it is possible to easily manufacture a master disc of an optical disk according to various specifications. Moreover, the optimization of signal characteristics according to various specifications and the setting of conditions necessary for manufacturing can be performed very easily, and the development of an optical disk can be efficiently performed.

In the second embodiment, the beam diameter converting optical systems GPO and PPO and ZPO are installed between the beam expanding lenses GB2 and PB2 and the mirrors M3 and M5 and between the polarizing beam splitter PBS and the mirror M2, respectively. However, the beam expanding lenses GB2 and PB
Optical system GPO for converting the light beam diameter between the mirror 2 and the mirrors M3 and M5
And PPO may be omitted.

The light beam diameter converting optical systems GPO (PPO) and ZPO according to the first and second examples are as follows.
It may be mounted on an optical head of a recording and / or reproducing apparatus for recording and / or reproducing information signals on the optical disc. In this case, the optimization of the signal characteristics according to various specifications and the setting of the conditions necessary for manufacturing can be performed very easily, and the optical disc can be efficiently developed. In addition, it is possible to record and / or reproduce information signals on various types of optical disks or magneto-optical disks with one recording and / or reproducing apparatus.

In the first and second embodiments described above, the optical disk is mainly used as the disk-shaped recording medium. However, in addition to this, a step is formed between the magneto-optical disk and the recording area and the non-recording area. It can also be applied to the formed so-called discrete type magnetic disk.

[0073]

As described above, according to the disk-shaped recording medium manufacturing apparatus of the present invention, the resist film formed on the circular substrate is irradiated with the light beam modulated based on the recording data, In a disk-shaped recording medium manufacturing apparatus for manufacturing a disk-shaped recording medium master by exposing and recording a data pattern based on the recording data, a light beam diameter conversion optical system for varying the diameter of the light beam is provided. Therefore, it is possible to arbitrarily and easily change the light beam diameter of the light beam according to various specifications of the disk-shaped recording medium, and it is possible to easily manufacture the master disk of the disk-shaped recording medium according to the various specifications. it can. Further, it is possible to very easily optimize the signal characteristics according to various specifications and set the conditions necessary for manufacturing, and it is possible to efficiently develop the disk-shaped recording medium.

[Brief description of drawings]

FIG. 1 is a first embodiment in which a disk-shaped recording medium manufacturing apparatus according to the present invention is applied to a laser cutting apparatus used in manufacturing an optical disk master (hereinafter, simply referred to as a laser cutting apparatus according to the first embodiment). It is a block diagram showing).

FIG. 2 is a configuration diagram of a main part of the laser cutting apparatus according to the first embodiment.

FIG. 3 is an explanatory diagram showing a configuration and an operation of a light beam diameter conversion optical system arranged in a subsequent stage of the groove optical system and the pit optical system of the laser cutting apparatus according to the first example.

FIG. 4 is a characteristic diagram showing a light beam diameter conversion characteristic of the light beam diameter conversion optical system according to the first example, in particular, a conversion characteristic of a light beam diameter magnification according to a first distance between a first converging lens and a diverging lens. Is.

FIG. 5 is a characteristic diagram showing a light beam diameter conversion characteristic of the light beam diameter conversion optical system according to the first example, in particular, a conversion characteristic of a light beam diameter magnification according to a second distance between a diverging lens and a second converging lens. Is.

FIG. 6 is a side view showing a configuration of a lens group constituting a light beam diameter conversion optical system, FIG. 6A shows a configuration of a first converging lens, FIG. 6B shows a configuration of a diverging lens, and FIG. C is second
The structure of the converging lens of is shown.

FIG. 7 is an explanatory diagram showing a change state of a laser beam diameter emitted from the beam diameter converting optical system in each optical system.
Shows the intensity distribution of the beam shape of the laser beam emitted from the beam diameter conversion optical system, B in the figure shows the ratio that fills the pupil plane of the objective lens, and C in the figure shows the focused beam with which the photoresist film is irradiated. The intensity distribution of the shape is shown.

FIG. 8 is a characteristic diagram showing a setting range of signal characteristics in the laser cutting apparatus according to the first embodiment.

FIG. 9 is a configuration diagram showing a main part of a laser cutting device according to a modification of the first embodiment.

FIG. 10 is a second example in which the disk-shaped recording medium manufacturing apparatus according to the present invention is applied to a laser cutting apparatus used when manufacturing a master for an optical disc (hereinafter, simply referred to as a laser cutting apparatus according to the second example. It is a block diagram showing).

FIG. 11 is a configuration diagram showing a main part of a laser cutting device according to a second embodiment.

FIG. 12 is an explanatory diagram showing a configuration and an action of a light beam diameter conversion optical system arranged in front of an objective lens of a laser cutting apparatus according to a second example.

FIG. 13 is a configuration diagram showing a laser cutting device according to a conventional example.

FIG. 14 is a configuration diagram showing a main part of a laser cutting device according to a conventional example.

[Explanation of symbols]

1 laser light source 2 circular substrate 3 Photoresist film L (L1, L2) laser light HM half mirror M1 to M5 mirror G groove optical system P-pit optical system GB1, PB1 beam reduction lens GB2, PB2 beam expansion lens GA, PA AOM GPO, PPO, ZPO Luminous flux diameter conversion optical system PBS polarization beam splitter LE convergent lens element OB objective lens La first converging lens Lb divergent lens Lc Second converging lens S1 first distance S2 second distance 11,12 lens group S shifter

Claims (3)

(57) [Claims] 1. A disc-shaped recording medium is formed by exposing a resist film formed on a circular substrate with a light beam modulated based on recording data to expose and record a data pattern based on the recording data. In a disk-shaped recording medium manufacturing apparatus for producing a master, an optical system for modulating the light beam with a recording signal, a beam diameter conversion optical system for changing the diameter of the light beam, and a laser beam incident from a polarization beam splitter. An optical system that has a converging lens element that changes the focal length of light and that modulates the above-mentioned light beam with a recording signal is a beam reduction lens that narrows the beam of the laser light through a half mirror, and is modulated with the recording signal. An acousto-optic modulator that intensity-modulates the laser light from the beam reduction lens based on the ultrasonic wave, and a parallel-light intensity-modulated laser light from the acousto-optic modulator. The beam diameter conversion optical system, which is composed of a beam expanding lens that converts the light beam to the original beam diameter and changes the diameter of the light beam, includes at least a first converging lens and a diverging lens along the traveling direction of the light beam. It has a lens and a second lens group arranged in this order of the convergent lens, movably to the beam diameter of the light beam incident on the lens group, a fixed said first converging lens
And a second distance between the diverging lens and the movable second converging lens.
An apparatus for manufacturing a disk-shaped recording medium, which has a structure that can be changed in accordance with a change in the distance. 2. The light beam diameter conversion optical system is installed in a non-parallel light beam immediately after it in an optical modulator that modulates the light beam based on recording data, and at least along the traveling direction of the light beam. There is a lens group in which a first converging lens, a diverging lens, and a second converging lens are arranged in this order, and the luminous flux diameter of the light beam incident on this lens group is set between the first converging lens and the diverging lens. Of the first divergence lens and the second distance between the diverging lens and the second converging lens, and a shifter for correcting the optical axis is installed behind the second converging lens. The disk-shaped recording medium manufacturing apparatus according to claim 1, wherein the manufacturing apparatus has a structure. 3. A resist film formed on a circular substrate is irradiated with a light beam modulated based on recording data, and a data pattern based on the recording data is exposed and recorded, whereby a disc-shaped recording medium is formed. In a disk-shaped recording medium manufacturing apparatus for producing a master, an optical system for modulating the light beam with a recording signal, a beam diameter conversion optical system for changing the diameter of the light beam, and a laser beam incident from a polarization beam splitter. An optical system that has a beam diameter conversion optical system that changes the focal length of light and that modulates the above-mentioned light beam with a recording signal includes a beam reduction lens that narrows the beam of laser light through a half mirror and a recording signal. The acousto-optic modulator that intensity-modulates the laser light from the beam reduction lens based on the modulated ultrasonic wave and the intensity-modulated laser light from the acousto-optic modulator are parallel to each other. The beam diameter conversion optical system, which is composed of a beam expanding lens that converts the beam into a bundle and returns it to the original beam diameter, and that changes the diameter of the light beam is installed immediately before the objective lens in which the light beam is a parallel light beam, Along the traveling direction of the light beam, at least the first
The convergent lens has a sequentially arranged a lens group of the diverging lens and the second converging lens, move the beam diameter of the light beam incident on the lens group, and movable and have been the first converging lens The first distance between the divergent lenses enabled and the second distance between the divergent lens and the second convergent lens fixed to the divergent lens are made variable, and a set of different focal lengths are formed at the same focal point. An apparatus for manufacturing a disk-shaped recording medium having a structure for emitting light.