JPH0752524B2 - Optical disc master making device - Google Patents

Description

The present invention relates to an apparatus for producing an optical disk master.

(Prior Art) An optical disk master (hereinafter simply referred to as a master) has a substrate such as glass whose surface is polished coated with a photoresist (hereinafter simply referred to as a resist), and the intensity of which is modulated by an information signal to be recorded. A laser beam is used for photosensitization, and information recording corresponding to the photosensitivity is formed on the master.

FIG. 9 shows the configuration of such a conventional master forming apparatus, mainly the laser light irradiation configuration. A substrate 1 coated with a resist is rotatably driven by a spindle 2 and is uniaxially transferred. The platform 3 transfers the substrate 1 in the radial direction. Laser light emitted from the Ar (argon) laser 4 passes through a mirror 5 and an intensity modulator (referred to as an E-O modulator).
Intensity modulation according to the signal intensity to be recorded is carried out by 6, and the substrate 1 is irradiated by a lens actuator (hereinafter simply referred to as actuator) 10 via mirrors 7, 8 and a filter mirror 9. He-Ne (helium neon) laser
The laser light from 11 is applied to the substrate 1, and the returned light is sent to the photodetector 13 via the half mirror 12, and the actuator 10 focuses the laser light of the Ar laser 4 on the substrate 1 by the detection output. Control to tie. The resist of the substrate 1 is a resist that is sensitive to Ar laser light and is not sensitive to He-Ne laser light.

(Problems to be Solved by the Invention) Since the conventional optical disk master is created as described above,
A laser device that oscillates two laser lights for recording and focus adjustment control (abbreviated as recording light and control light, respectively) (Ar laser device, He-Ne laser device in the above example)
Two pieces are required, so that the size of the master forming device becomes large, and the laser beam whose intensity is modulated by the recording signal of the substrate provided with the track groove (hereinafter referred to as the recording groove or groove) is irradiated while performing the tracking control. In this case, there is a defect that the focal spots of the recording light and the control light are relatively displaced.

It is an object of the present invention to provide a device for producing an optical disc master that eliminates the above drawbacks.

(Means for Solving the Problems) The present invention has the above-mentioned object by providing one laser device that simultaneously oscillates at two or more wavelengths, and uses one of the oscillated laser beams as recording light to increase the intensity. This is achieved by modulating and using for recording a signal, and using another oscillating laser light as control light for adjusting and controlling the focus of recording light or the like.

(Operation) Since the present invention supplies both recording and control laser light from a single laser device, the device can be constructed in a small size.
Since the relative positions of the spots of the laser light for recording and controlling do not easily collapse, it is possible to create an excellent master of an optical disc.

(Examples) Hereinafter, the present invention will be described in detail with reference to Examples.

FIG. 1 is a diagram showing a configuration of an optical disc master making apparatus according to an embodiment of the present invention. Reference numerals not described below are based on the explanations up to the previous figure, and other reference numeral 14 is a dual wavelength capable of oscillating two wavelengths. It is an oscillating Ar laser, the oscillating light of which is a filter mirror 15
Is divided into two by one, and the laser light of one is E-
The O modulator 6 modulates the intensity according to the signal to be recorded, and the substrate 10 coated with the resist by the actuator 10 is used as recording light for exposing the resist for irradiating the laser beam spot (focus). Of the laser light is radiated to the substrate 1 through the actuator 10, and the return light reflected by the substrate 1 is detected by the photodetector 13 through the filter mirror 9 and the half mirror 12, and the detection output signal includes the actuator 10 and the substrate 1. Since a change is obtained depending on the distance between and, it is used for controlling the actuator 10 that can form the spot of the recording light on the substrate 1.

Astigmatism method, knife edge method and the like are known as methods for forming such control light. For example, in the knife edge method,
A return light from the substrate is converged by a lens or the like, a knife edge is arranged in the convergent optical path between the lens and the focal plane to block half of the optical path, and a photodetector divided into two is placed on the focal plane. In this way, the output difference of the photodetector divided into two is obtained according to the distance between the substrate and the actuator, and this can be used as a signal for focus control of the actuator. In the present invention, such photodetectors capable of focus control are collectively referred to as a photodetector.

The substrate 1 is rotationally driven by the spindle 2 and is transferred in the radial direction of the substrate 1 by the uniaxial transfer table 3 as in the conventional case.

The two-wavelength oscillating Ar laser 14 can be constructed by using a mirror of a laser resonator having a high reflectance at two specific wavelengths of the oscillating wavelength, and the intensity ratio of the two oscillating laser beams is the same. It can be realized by adjusting the difference in the reflectance of the resonator, and the oscillation wavelength can be, for example, 457.9 nm for recording light and 514.5 nm for control.

In addition to Ar laser, krypton laser and He laser can be used as the two-wavelength oscillation laser, and the resist having high sensitivity for recording light and low sensitivity for control light can be arbitrarily selected. Since the sensitivity of the resist is higher for laser light of shorter wavelength than long wavelength,
It is advantageous to use long-wavelength laser light for control. Further, the substrate 1 is generally a glass plate whose surface is polished, but this may be another plate such as a copper plate.

FIG. 2 shows an embodiment in which laser light of two wavelengths is produced from an Ar laser of multimode oscillation. The same reference numerals as those in the previous figures not described below have the same or equivalent functions, and 16 indicates a multi-mode. By using a mode-oscillating Ar laser, one of a plurality of oscillating laser beams is selected as a control beam through the filter mirror 15, and another laser beam is selected as a recording beam by the filter mirror 17. The signal can be recorded on the substrate 1 in exactly the same manner as in FIG. As the multimode oscillation 16, a krypton laser or a He-Ne laser can be used in addition to the Ar laser.

FIG. 3 is a block diagram of another embodiment. Reference numeral 18 is a grooved substrate on which recording grooves are formed in advance and a resist is applied. Photo detector
Reference numeral 13 detects a tracking signal by the recording groove of the grooved substrate 18 in addition to the focus signal. A galvanometer mirror 19 is controlled by the tracking signal, enables a shake at a minute angle around an axis perpendicular to the paper surface, and tracks the recording light in the recording groove of the grooved substrate 18.

Here, the recording groove of the grooved substrate 18 may be a general groove having a U or V cross section, which can be formed by mechanical cutting.
It is difficult to cut simultaneously with address cutting. Therefore, the address is recorded using a substrate provided with a recording groove in advance,
Therefore, tracking is applied.

The control light and the recording light form a focal spot on the grooved substrate 18 by the actuator 10, and these spots may be at the same point and on the recording groove. Further, as shown in FIG. 4 (a), It may be on a straight line in the groove direction. Similarly, if the control light spot 21 is located on the groove and the recording light spot 20 is located between the grooves as shown in FIG. 6B, a signal can be recorded between the grooves.

In case of V groove, both spots of recording light and control light 20,21
May be linear in the valley in the groove direction as shown in FIG. 5 (a), or may be at the crest of the groove as shown in FIG. 5 (b). Further, both spots 20 and 21 may be at the same point and may be on the bottom or peak of the V groove, and in either case, the signal can be recorded on the bottom or peak of the V groove. Further, as shown in FIGS. 6A and 6B, the spot 21 of the control light is
Is placed on the bottom or ridge of the V-groove and the spot of the recording light is placed on the slope of the V-groove, recording can be performed on the slope, so that recording on both slopes provides an optical disc on which twice as much information as the conventional information is recorded. A master can be made.

Generally, in a device for producing an optical disk master, when the positional relationship between the spots of the recording light and the control light is not constant, the recording signal causes track deviation and crosstalk occurs during reproduction.

The main cause of the positional deviation between the two spots is the fluctuation due to the temperature of the laser resonator. However, in the present invention, since both the recording light and the control spot are created from the same laser device, there is fluctuation due to the temperature. However, their relative positions do not change, and therefore crosstalk or the like is less likely to occur. Further, even if the spot of the control light fluctuates, tracking is performed thereby, so that there is no effect on the signal recording.

FIG. 7 shows still another embodiment of the present invention in which signals are recorded on both slopes of the V groove.

The recording light is separated from the two-wavelength oscillating Ar laser 14 into two wavelengths by the filter mirror 15, and one of the laser lights to be the recording light is divided into two by the half mirror 22, and the EO modulators 6 and 6'are used. Intensity modulation according to the recording signal strength, and one side of the polarization plane is set by the half-wave plate 23.
Since they are shifted by 1/2 wavelength, one recording light is made by the PBS (polarizing beam splitter) 24, and the recording light and the control light are focused on the substrate 25 having the V groove coated with the resist through the galvano mirror 19 and the actuator 10. Beam is emitted, and the spots of the control light are placed on the ridges of the V groove as shown in FIG. 8 (a), and the spots 20 and 20 'of the two recording lights are formed on both slopes of the above ridge. Or the control light spot 21 is placed in the valley of the V-groove and the two recording light spots 20 and 20 'are placed on both slopes of the valley of the V-groove, respectively, as shown in FIG. Then, while controlling the peaks or valleys of the V groove with the control light 21, the recording light 20 and 20 'whose intensity is modulated by different signals simultaneously cause V
Signals can be recorded on both slopes of the groove.

(Effects of the Invention) As will be apparent from the detailed description given above, since the present invention obtains recording light and control light from one laser device to record a signal, the two laser devices conventionally required are used. One side can be omitted and the size can be reduced, and at the same time, the relative position between the recording light spot and the control light spot can be achieved by forming a recording groove on a substrate coated with a resist and recording a signal while tracking. Since the gap is less likely to shift, it is possible to create a master with significantly improved recording quality.

[Brief description of drawings]

1, FIG. 2, FIG. 3, and FIG. 7 are views showing an embodiment of the present invention, FIG. 4, FIG. 5, FIG. 6, FIG.
FIG. 9 is an auxiliary diagram for explaining the spots connecting the recording light and the control light of the present invention on the substrate, and FIG. 9 is an explanatory view of a conventional example. 1 ... Glass substrate, 2 ... spindle, 3 ... uniaxial transfer table, 4 ... Ar (argon) laser, 5,7,8 ... mirror,
6,6 ′ …… Intensity modulator (EO modulator), 9,15,17 …… Filter mirror, 10 …… Lens actuator (abbreviated as actuator), 11 …… He-Ne (helium neon) laser, 12,22 …… Half mirror, 13 …… Photodetector, 14 ……
Two-wavelength oscillating Ar laser, 16 …… Multimode oscillating Argon laser, 18 …… Grooved substrate, 19 …… Galvano mirror, 20, 2
0 '... recording light spot, 21 ... control light spot, 23 ...
… 1/2 wave plate, 24 …… PBS (polarizing beam splitter), 25
...... V-grooved substrate.

Claims (1)

[Claims] 1. An apparatus for producing an optical disk master recorded with a recording signal, which comprises a step of irradiating an optical disk substrate coated with a photoresist with a laser beam whose intensity is modulated by the recording signal. A laser beam and a control laser beam for controlling the formation of a focal spot of the recording laser beam on the substrate are supplied from one laser device that oscillates the laser beam at at least two or more different wavelengths. An optical disc master making device.