JPH0935308A - Information recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify assembling adjustment when a laser light source is exchanged and to improve excellently reproducibility in an optical axis and a beam shape of an outgoing beam. SOLUTION: An outgoing beam A from the laser light source 1 is led to a beam adjustment optical system 10 arranged on the prestage of an irradiation optical system 2 and capable of adjusting the beam shape and the optical axis. Thus, the shaping of the beam shape and the optical axis adjustment of the outgoing angle/outgoing position of the outgoing beam A are performed precisely without performing the assembling adjustment in the laser light source 1 and the irradiation optical system 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information recording device used as an optical disk master exposure device or the like.

[0002]

2. Description of the Related Art FIG. 10 (a) is a block diagram showing the structure of a conventional general information recording apparatus. The emission beam A emitted from the laser light source 1 is condensed by the objective lens 3 via the irradiation optical system 2 and is irradiated onto the surface of the optical disc (optical information recording medium) 4 in the form of a minute light spot. As a result, information is recorded at the desired recording position. In this case, when an optical disk master exposure device is taken as an example of the information recording device, a beam A emitted from the laser light source 1
Is digitally modulated by the exposure optical system (irradiation optical system 2) and is irradiated onto the surface of the optical disk master (optical disk 4) to create pits (about 1 μm) or grooves having a desired shape, and thereby information of Recording is done.

[0003]

The life of the laser light source 1 (Ar, Kr laser, He-Cd laser, etc.) used as a light source for recording such information is generally 2000-.
It is 3000 hours, and regular replacement is performed. However, since the optical characteristics of the laser light source 1 (divergence angle of emitted beam, beam diameter, Gaussian distribution shape, etc.) are often different depending on each light source, the emission position and the emission angle of the laser light source 1 are changed at each periodical replacement. The optical axis adjustment and the assembly adjustment of the irradiation optical system 2 have to be performed, resulting in poor work efficiency. In particular, in the case of an optical disk master exposure device, since the laser light source 1 is often a large heavy object (around 40 kg), it takes time to adjust its movement, and the same beam state is applied even in the assembly adjustment of the irradiation optical system 2. Is very difficult to reproduce. In addition, if the optical axis is automatically adjusted inside the irradiation optical system 2, the number of parts increases, which increases the size of the optical system and increases the cost.

In order to simplify such optical axis adjustment, an optical axis correction unit 5 is provided between the laser light source 1 and the irradiation optical system 2 as shown in FIG. 10 (b). There are some (see Japanese Patent Publication No. 6-95174). FIG. 11 shows a configuration example of the optical axis correction unit 5, in which the optical axes are adjusted using the servo mirrors 6 and 7. That is, a part of the outgoing beam A is divided into four light receiving elements 8
And the rotation of the servo mirrors 6 and 7 is controlled by the motor 9 to adjust the optical axis of the outgoing beam A (correct the outgoing position and outgoing angle, etc.).

However, the optical axis correction unit 5 adjusts the optical axis of the outgoing beam A and does not perform beam shaping of the beam shape (correction of astigmatism etc.).
Therefore, if the optical axis correction unit 5 that does not have such a function of adjusting the optical axis is used for an optical disk master exposure device that requires particularly fine pits (for example, a diameter of 1 μm or less), It is difficult to satisfactorily reproduce the desired beam shape every time the laser light source 1 is replaced, and the groove shape cannot be stably formed.

[0006]

According to the first aspect of the invention, the beam emitted from the laser light source is guided to the beam adjusting optical system to adjust not only the emission position and the emission angle of the emitted beam, but also the beam. The shape is shaped. The emission beam adjusted in this way is guided to the irradiation optical system and subjected to modulation control, and then is condensed by the objective lens to become a desired minute light spot, and this light spot is irradiated to the optical information recording medium. The information is recorded.

According to the second aspect of the present invention, the outgoing beam from the laser light source is guided to the beam diameter regulating member, whereby an outgoing beam having a constant beam diameter is created.
The outgoing beam having a constant beam diameter is applied to the optical information recording medium via the beam adjusting optical system.

According to the third aspect of the invention, the beam emitted from the laser light source is guided to the pair of cylindrical lenses and moved in the direction in which the lens curvature is formed, whereby the beam can be shaped in one direction. Becomes

According to another aspect of the present invention, the beams emitted from the laser light source are guided to the cylindrical lenses in which the directions in which the lens curvatures of each set are formed are orthogonal to each other, so that different beam shaping in two directions is performed simultaneously. It becomes possible.

According to the fifth aspect of the present invention, the amount of fluctuation of the light quantity can be reduced to 1 / m by guiding the beam emitted from the laser light source to the beam expander.

According to the sixth aspect of the present invention, it is possible to monitor the beam adjustment in each direction by guiding the outgoing beam adjusted by the cylindrical lens to the beam extraction means and extracting it as sample light. .
Further, by using, for example, a dichroic mirror as the beam extracting means, it is possible to maintain the polarization direction of the main beam for recording which is not extracted.

In the invention described in claim 7, by guiding the extracted sample light to the polarization separation means, it is possible to form two beams of P-polarized light and S-polarized light from the one sample light. Become.

According to the present invention, the position adjusting light receiving means can be used to monitor the optical axis position of the outgoing beam, and the angle / beam shape adjusting light receiving means can be used to output the outgoing angle of the outgoing beam or The beam shape can be monitored.

In the ninth aspect of the invention, a plurality of sample lights extracted by the beam extracting means are guided to one light receiving means for adjusting the angle / beam shape so that different beam spots are formed on the same monitor surface. The position can be adjusted at the same time.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. Incidentally, here, as the information recording apparatus, the above-mentioned optical disk master exposure device (see FIG. 10) is used.
The same reference numerals are used for the same portions.

FIG. 1 shows the structure of an optical disk master exposure device. This master exposure apparatus is roughly divided into a laser light source 1, a beam shaping unit 10 as a beam adjusting optical system, and an exposure optical system 2 as an irradiation optical system. In this case, the laser light source 1 and the exposure optical system 2 are composed of known members. For example, the laser light source 1 is composed of an ion laser (Ar laser, He-Cd laser, etc.). The irradiation optical system 2 includes an analog modulator 11 and a digital modulator 12
, A deflector 13, and a pair of beam expanders 14a,
14b and.

The configuration of the beam shaping unit 10 will be described here. As shown in FIG. 2, a pinhole plate 1 as a beam diameter regulating member is provided on the emission optical path of the laser light source 1.
5 are arranged. At the center of the pinhole plate 15, a pinhole 15a having a diameter smaller than the beam diameter of the outgoing beam A is formed. This pinhole plate 15
A pair of cylindrical lenses 16a and 16b are arranged on the optical path whose beam diameter is restricted by. The direction in which the curvatures of the cylindrical lenses 16a and 16b change is set in the X direction (horizontal direction) orthogonal to the optical axis direction Y.

Further, the cylindrical lenses 16a, 16
A dichroic mirror 17 as a beam extraction means is arranged in the subsequent stage of b in order to separate a part of the outgoing beam A to produce the sample light B. A pair of cylindrical lenses 1 is provided at the rear stage of the dichroic mirror 17.
8a and 18b are arranged. The direction in which the curvatures of the cylindrical lenses 18a and 18b change is set to the vertical direction Z in the vertical plane orthogonal to the optical axis direction Y.
Thereby, the cylindrical lenses 18a and 18b,
Cylindrical lenses 16a, 1 arranged in the preceding stage
6b is arranged such that the directions in which the curvature is formed are orthogonal to each other. In this case, as shown in FIG. 3, the cylindrical lenses 16b and 18b are respectively configured as beam expanders having a beam expander ratio of m times (m> 1) with respect to the cylindrical lenses 16a and 18a. In addition, such a cylindrical lens 18
The dichroic mirror 17 is provided after the a and 18b.
A dichroic mirror 19 is disposed as a beam extraction means having a separation function similar to.

On the optical path of the sample light B separated by the dichroic mirror 17, a λ / 2 plate 20 and
A polarization beam splitter 21 is arranged. The λ / 2 plate 20 and the polarization beam splitter 21 constitute a polarization separation means for separating the sample light B into two directions (S polarization and P polarization). A CCD 22 is arranged on the optical path reflected by the polarization beam splitter 21, and the CCD 22 is connected to a monitor 23. On the other hand, a two-divided light receiving element (or PSD: Position Sensi) is provided on the optical path that has passed through the polarization beam splitter 21.
A tive device 24 is arranged. The two-divided light receiving element 24 is connected to the display 25. In addition, CCD
The monitor 22 and the monitor 23 constitute a light receiving means for adjusting the angle / beam shape, and the two-divided light receiving element 24 and the display 25 constitute a light receiving means for position adjustment.

Also, on the optical path of the sample light B separated by the dichroic mirror 19, the same optical system as on the optical path separated by the dichroic mirror 17, that is, the λ / 2 plate 26, the polarization beam splitters 27, 2 is used. The divided light receiving elements 28 are sequentially arranged. However, here, the light reflected by the polarization beam splitter 27 is
The light is guided to the CCD 22 via the λ / 2 plate 29 and the polarization beam splitter 21 in the preceding stage, and also the two-divided light receiving element 24.
Is connected to the above-mentioned display 25.

The operation of the present apparatus having such a configuration will be described. The outgoing beam A from the laser light source 1 is guided to the exposure optical system 2 via the beam shaping unit 10 in FIG. In the exposure optical system 2, the outgoing beam A is converted into an optimum light amount by the analog modulator 11, converted into pulsed light according to the information signal by the digital modulator 12, and further, via the deflector 13, the beam extractor. Panda 1
It is converted into a predetermined beam diameter by 4a and 14b. The outgoing beam A thus converted is condensed by the objective lens 3 to form a minute light spot, which is exposed on the surface of the optical disc master 4 which is rotationally controlled by the slide turntable 4a, whereby a desired shape is obtained. Information is recorded by forming pits and grooves.

At this time, if it is assumed that the laser light source 1 has been replaced due to its service life, the following adjustment is performed using the beam shaping unit 10. First, the emission beam A emitted from the laser light source 1 is guided to the pinhole 15a. As a result, as shown in FIG. 4, the XY plane and the Y-
The beam diameter can be shaped to be constant with respect to the Z plane, and the installation position of the laser light source 1 can be easily confirmed. Then, the outgoing beam A whose beam diameter is shaped in this manner enters the cylindrical lenses 16a and 16b as shown in FIG. By moving each of the cylindrical lenses 16a and 16b in the curvature direction X, it is possible to adjust the emission angle and the emission axis of the emission beam A with respect to the curvature direction X. Also, the cylindrical lenses 16a, 1
By moving 6b in the optical axis direction Y, the beam parallelization can be shaped. In this way, the cylindrical lenses 16a and 16b are moved in the curvature direction X,
By moving in the optical axis direction Y, the optical axis of the outgoing beam A and the beam shaping of the beam shape can be easily performed. Note that the shaping in the vertical direction Z is not performed here.

In this way, the cylindrical lens 16
The outgoing beam A, which has been beam-shaped in only one direction by a and 16b, is guided through the dichroic mirror 17 to the cylindrical lenses 18a and 18b in the subsequent stage. In the cylindrical lenses 18a and 18b, as shown in FIG.
As shown in, the emission angle and the emission position are adjusted with respect to the curvature in the vertical direction Z orthogonal to the X direction. Thereby, the beam divergence angles in the X and Z directions can be equalized to form the outgoing beam A having a beam shape without astigmatism. Thus, the cylindrical lenses 16a and 16b and the cylindrical lens 18 whose curvature directions are orthogonal to each other.
The combination of a and 18b can improve the accuracy of beam shaping. In addition, since the outgoing beam A can be adjusted independently in the X and Z directions in this way, one beam shaping does not affect the other beam shaping, and the adjustment can be performed accurately and accurately. Easy to do.

In addition, the cylindrical lens 16 in the previous stage
a, 16b and the subsequent cylindrical lenses 18a, 1
8b, the beam expander ratio is m times as shown in FIG. As a result, when the optical axis variation of the outgoing beam A is, for example, θ ₀ , the cylindrical lens 16
The optical axis fluctuation amount after passing through a and 16b is θ ₁ = θ ₀ / m. Further, the outgoing beam A whose optical axis fluctuation amount is set to θ ₁ passes through the cylindrical lenses 18a and 18b, so that the optical axis fluctuation amount becomes θ ₂ = θ ₁ / m. Even if the optical axis of the laser light source 1 itself fluctuates in this way, the amount of optical axis fluctuation can be reduced to 1 / m in each beam expander. Since there are two sets here, the beam shaping unit The optical axis variation after passing 10 is 1
It can be significantly reduced to / m ² . This allows
It is possible to prevent the beam shape from changing in the exposure optical system 2 in the subsequent stage, and it is possible to accurately form the groove shape formed in the optical disc master 4.

The outgoing beam A (main beam) is separated by the dichroic mirrors 17 and 19, whereby sample light B for monitoring is produced. That is, as shown in FIG. 7, the outgoing beam A is separated by the dichroic mirror 17 in the preceding stage, and 1% thereof is reflected to become the sample light B. By disposing this dichroic mirror 17 on the optical path, it is possible to maintain the polarization direction of the transmitted main beam (exit beam A) in the same beam state as before the disposition, so that in the exposure optical system 2 in the subsequent stage. It is possible to prevent the light amount from being lost due to the deviation of the direction.

In this way, the dichroic mirror 17
As shown in FIG. 8, the linearly polarized sample light B separated by is incident on the polarization beam splitter 21 via the λ / 2 plate 20, and is thus separated into P-polarized light and S-polarized light. Here, the transmitted light is P-polarized light and the reflected light is S-polarized light.
If it is polarized light, the sample light B composed of one of the P-polarized light
Is received by the two-divided light receiving element 24. By displaying the received signal on the display 25, the deviation of the optical axis of the outgoing beam A from the predetermined position can be easily known. By adjusting the cylindrical lenses 16a and 16b so that the displayed numerical value becomes the same value as before the replacement of the laser light source 1, the same optical axis position as before the replacement can be reproduced. On the other hand, the sample light B composed of S-polarized light reflected by the polarization beam splitter 21 is received by the CCD 22, and a beam spot is projected on the monitor 23. In this case, by adjusting the cylindrical lenses 16a and 16b so that the monitor image has the same position and the same spot size as before the replacement of the laser light source 1, the same emission angle and beam shape as before replacement can be reproduced. be able to.

Further, the sample light B separated by the dichroic mirror 19 in the subsequent stage is, as shown in FIG.
It is guided to the polarization beam splitter 27 via the / 2 plate 26 and split into two beams. Here, the S-polarized light reflected by the separation becomes P-polarized light via the λ / 2 plate 29, passes through the polarization beam splitter 21 in the preceding stage, and is CCD.
Light is received at 22. As a result, two beam spots are projected on the monitor 23. Therefore, by making these two beam spots coincide with each other, it is possible to eliminate the angular deviation generated during beam shaping. Also, 2
By matching the sizes of the individual beam spots, the beam shapes in the X and Z directions can be made equal. Further, by adjusting so that the matched beam spots have the same position and the same size as before the replacement of the laser light source 1, the same beam shape with the same position and emission angle as before the replacement is obtained. It can be reproduced.

As described above, the beam shaping unit 10
With the provision of the beam shape, not only the optical axis adjustment by the laser light source 1 and the exposure optical system 2 as in the conventional case but also the adjustment of the emission position and the emission angle of the emission beam A, and the accurate beam shaping are performed. Can be reproduced satisfactorily, and as a result, even when the laser light source 1 is replaced due to its service life, the work efficiency of the assembly adjustment can be improved.

Although the optical disk master exposure device is taken as an example of the information recording apparatus, the information recording apparatus is not limited to this, and any recording apparatus that records on a medium such as an optical disk may be used. Beam conditioning optics may be incorporated into the device.

[0030]

According to the first aspect of the present invention, since the beam adjusting optical system for adjusting the beam shape and the optical axis is provided on the optical path between the laser light source and the irradiation optical system, the laser light source is selected depending on the life. Even in the case of replacement, without adjusting the optical axis by the laser light source and irradiation optical system as in the past,
The beam shape and the emission position and the emission angle of the emission beam can be reproduced well, which can significantly reduce the work time for assembly adjustment when replacing the laser light source, and with a simple configuration. It is possible to provide an information recording device equipped with a low-cost beam adjusting mechanism.

According to the second aspect of the invention, since the beam emitted from the laser light source is guided to the beam diameter regulating member, the difference in beam diameter caused by replacement of the laser light source can be made constant. It is possible to perform beam adjustment under constant conditions.

According to the third aspect of the present invention, the beam emitted from the laser light source is guided to a pair of cylindrical lenses that are movable in the direction in which the lens curvature is formed and in the optical axis direction. It is possible to perform the optical axis adjustment of the emission angle and the emission position independently.

According to the invention described in claim 4, since two sets of cylindrical lenses are installed so that the directions in which the lens curvatures of each set are formed are orthogonal to each other, the beam shaping is performed independently in each of the two directions. As a result, the emitted beam can have the same beam shape as that before the replacement of the laser light source.

According to a fifth aspect of the invention, the beam emitted from the laser light source has a beam expander ratio of m times (m> 1).
Since the beam expander is guided to the beam expander, even if the light amount variation occurs in the emitted beam of the laser light source, the amount of the light amount variation can be reduced to 1 / m per pair of beam expanders. Therefore, when such a beam expander is used in, for example, an optical disk master exposure device, it is possible to always stably form the groove shape in the optical disk master.

According to the sixth aspect of the invention, since the output beam after shaping is extracted as the sample light by using the beam extraction means, the sample light is monitored further without changing the polarization direction of the output beam. You can make precise adjustments.

In the invention described in claim 7, since the extracted sample light is guided to the polarization separating means, one sample light can be separated into two beams, whereby the outgoing beam It is possible to monitor two types of states.

According to the present invention, the position adjusting light receiving means is arranged on one optical path separated by the polarization separating means, and the angle / beam shape adjusting light receiving means is arranged on the other optical path. Therefore, it is possible to simultaneously monitor the optical axis position of the outgoing beam and the two types of states of the outgoing angle or the beam shape, which allows the outgoing beam adjustment work to be performed efficiently.

According to the ninth aspect of the invention, since the plurality of sample lights extracted by the beam extracting means are guided to the light receiving means for adjusting the angle / beam shape, it is possible to easily align the different beam spots. This makes it possible to more accurately adjust the emission angle of the emitted beam.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an optical disk master exposure device that is an embodiment of the present invention.

FIG. 2 is a perspective view showing the overall configuration of a beam shaping unit.

FIG. 3 is an optical path diagram showing how an optical axis variation is reduced by a beam expander.

FIG. 4 is a perspective view showing a state in which a pinhole is arranged in front of a cylindrical lens.

FIG. 5 is a perspective view showing how beam shaping is performed using a set of cylindrical lenses.

FIG. 6 is a perspective view showing how beam shaping is performed using two sets of cylindrical lenses.

FIG. 7 is a plan view showing an optical system of a portion for extracting sample light.

FIG. 8 is a plan view showing an optical system for monitoring the position, angle, and beam shape of sample light.

FIG. 9 is a plan view showing an optical system arranged before and after monitoring an angle and a beam shape of sample light.

10A is a block diagram showing a configuration of a conventional information recording apparatus, and FIG. 10B is a block diagram showing a configuration when an optical axis correction unit is provided in FIG.

FIG. 11 is a perspective view showing a configuration example of a conventional optical axis correction unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 laser light source 2 irradiation optical system 3 objective lens 4 optical information recording medium 10 beam adjusting optical system 15 beam diameter regulating members 16a, 16b cylindrical lens 17 beam extracting means 18a, 18b cylindrical lens 19 beam extracting means 20, 21 polarization separating means 22 , 23 Angle / beam shape adjusting light receiving means 24, 25 Position adjusting light receiving means 26, 27 Polarization separating means 28 Position adjusting light receiving means

Claims (9)

[Claims] 1. Information for recording information by guiding a beam emitted from a laser light source to an objective lens through an irradiation optical system, and irradiating the beam condensed by the beam onto a surface of an optical information recording medium. In the recording apparatus, a beam adjusting optical system for adjusting a beam shape and an optical axis of the emitted beam is provided on an optical path between the laser light source and the irradiation optical system. 2. The information recording apparatus according to claim 1, wherein the beam adjusting optical system is provided with a beam diameter regulating member for regulating the beam diameter of the outgoing beam. 3. The information recording apparatus according to claim 1, wherein the beam adjusting optical system has a pair of cylindrical lenses that are movable in the direction in which the lens curvature is formed and in the optical axis direction. 4. The pair of cylindrical lenses is provided in two sets, and the pair of cylindrical lenses is installed such that the directions in which the lens curvatures of these sets are formed are orthogonal to each other. Recording device. 5. The pair of cylindrical lenses is configured as a beam expander having a beam expander ratio of m times (m> 1).
Information recording device described. 6. The information recording apparatus according to claim 4, further comprising a beam extraction unit for extracting the adjusted outgoing beam as sample light after the cylindrical lens. 7. The information recording apparatus according to claim 6, further comprising polarization splitting means for splitting the sample light extracted by the beam extracting means into two directions. 8. A light receiving means for position adjustment is arranged on one optical path separated by the polarization separating means, and a light receiving means for angle / beam shape adjustment is arranged on the other optical path. Item 7. The information recording device according to item 7. 9. The information recording apparatus according to claim 8, wherein a plurality of sample lights extracted by the beam extracting means are guided to the light receiving means for adjusting the angle / beam shape.