JPH03273538A - Apparatus for producing optical master disk - Google Patents

Abstract

PURPOSE:To allow the easy and well formation of guide grooves or address pits of a relatively broad width by recording the guide grooves or address pits by respectively two beams. CONSTITUTION:The laser beam from a laser beam source 1 is split to 1st, 2nd beams 3, 4 by a beam splitter 2. The 1st beam 3 is shaped to collimated beams of light by 1st, 2nd lenses 7, 8 and the 2nd beam 4 is made incident through an optical modulator 6 to an acoustooptical type optical modulator 9. The 2nd beam is split to a 3rd beam 10 and a 4th beam 11. The two beam spots can be arrayed on a straight line forming an angle with the rotating direction of a recording medium 16 if the direction diffracted by the acoustooptical type optical modulator 9 is adequately set at this time. The guide grooves or address pits are recorded by the two beam spots in such a manner, by which the recording at the width thereof varied freely is executed without making laborious optical axis adjustment. In addition, the efficient utilization of the laser beam necessary for recording.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical disc master manufacturing apparatus for manufacturing an optical disc master having a guide groove and an address focus, on which information can be recorded and reproduced optically, and which can also be erased. .

Conventional optical discs have guide grooves for optically guiding irradiated light and address pits having header information such as track addresses and sector addresses. Recording takes place in the guide groove. In order to record and reproduce information with high reliability, the width of the guide groove needs to be wider than the width of the address pit.

The configuration of a conventional optical disc master manufacturing apparatus will be described below with reference to FIG.

As shown in the figure, a laser beam emitted from a laser light source 1 is split into a first beam 3 and a second beam 4 by a beam splitter 2, each of which is intensity-modulated by optical modulators 5 and 6, and a lens 7. After passing through .8 and lenses 12 and 13, the beams are combined by a beam nuplitter 14 and irradiated onto the recording surface of a recording medium 16 through a recording lens 15 to record information. The configuration is such that the position of the second beam relative to the first beam 3 on the recording surface can be adjusted by changing the position at which the second beam 3 enters the lens 13. A similar configuration is proposed in, for example, Japanese Patent Laid-Open No. 60-50733.

Problem to be Solved by the Invention In such a conventional method, when changing the width of the guide groove or address hint, the lens 7.8 or the lens 12.13
This was done by changing the combination of focal lengths of the laser beams to increase the beam diameter of the laser beam incident on the recording lens 15, and by changing the diameter of the beam spot focused on the recording surface by the recording lens 15. For example, in order to form a wide guide groove, as shown in FIG.
6 is made thicker and the beam spot 25 is made smaller to form a narrower address hint.

However, in the above configuration, the width of the guide groove or address pit is determined by the combination of lenses 12 and 13 or lenses T and 8, so when changing the width, it is necessary to replace the lens, and the resulting light I had to make an axis adjustment. Furthermore, when increasing the width, the beam intensity per unit area decreases by increasing the diameter of the beam spot, so there is a drawback that the intensity of the laser beam required for recording increases.

Means for Solving the Problems In order to solve the above problems, the optical DENUK master disc manufacturing apparatus of the present invention splits an intensity-modulated laser beam into two, and directs all of the divided laser beams onto the recording surface. The configuration is such that it can be placed on a straight line that is perpendicular to the rotation direction of the recording medium.

Effect of the present invention With the above-described configuration, by recording a guide groove or address pit with two beam spots, recording can be performed by freely changing the width of the guide groove or address pit without making troublesome optical axis adjustment. The intensity of the laser beam can be used efficiently.

EXAMPLE Below, an optical disc master manufacturing apparatus according to an example of the present invention will be described with reference to the drawings.

Referring to FIG. 1, 1 is a laser light source, and 2 is a beam splitter, which splits the laser beam emitted from the laser light source 1 into a first beam 3 and a second beam 4.

5 and 6 are optical modulators that modulate the intensity of the first beam 3 and the second beam 4, respectively. 7 and 8 are a first lens and a second lens; the first beam 3 is focused by the first lens 7, and shaped into a parallel beam with a desired beam diameter by the second lens. Reference numeral 9 denotes an acousto-optic optical modulator that divides the second beam 4 into a third beam 10 that is 0th-order diffracted light and a fourth beam 11 that is 1st-order diffracted light. 12 and 13 are a third lens and a fourth lens; the third beam 1o and the fourth beam 11 are narrowed down by the third lens, and shaped into parallel beams with a desired beam diameter by the fourth lens. A beam splitter 14 combines the first beam 3, the third beam 10, and the fourth beam 11. A recording lens 15 focuses and irradiates the combined beam onto the recording surface of the recording medium 16.

The operation of the optical disc master manufacturing apparatus configured as described above will be described below with reference to FIGS. 1 and 2.

A laser beam emitted from a laser light source 1 is split into a first beam 3 and a second beam 4 by a beam splitter 2. The first beam 3 is intensity-modulated by the optical modulator 5 according to the header signal, and then shaped by the first lens 7 and the second lens 8 into a parallel beam having a desired beam diameter. On the other hand, the second
The beam 4 is intensity-modulated by the optical modulator 6 according to the signal of the guide groove, and then enters the acousto-optic optical modulator 9 . Here, the second beam is split into 0th-order diffracted light (third beam 10) and first-order diffracted light (fourth beam 11) by Puwogg diffraction. The third beam 10 and the fourth beam 11 are shaped into parallel beams with desired beam diameters by the third lens 12 and the fourth lens 13, respectively.

The shaped first beam 3, third beam 10, and fourth beam 11 are combined by a beam splitter 14, then enter a recording lens 15, and are focused and irradiated onto the recording surface of a recording medium 16. .

At this time, beam spots 18 and 19 formed by the third beam 1o and the fourth beam 11 being respectively focused on the recording lens 15 are determined by the angle formed by the two beams incident on the recording lens and the focal distance of the recording lens. They are separated by a certain distance, but their direction depends on the direction of the beam incident on the recording lens. Therefore, by appropriately setting the direction of diffraction of the acousto-optic light modulator 9, two beam spots can be formed on the recording surface in the rotational direction 20 of the recording medium 16 (i.e., in the track direction) as shown in FIG. ) are arranged on a straight line making a right angle to Further, the relative positions of the focused beam spot 17 of the first beam 3 and the focused beam spots 18 and 19 of the third beam 10 and the fourth beam 11 are such that the second lens 8 is perpendicular to the traveling direction of the laser beam. Adjustment can be made by moving the beam spot 17 between the beam spots 18 and 19.

By recording guide grooves and address pits using the three beams arranged as shown in Figure 2, relatively wide guide grooves and relatively narrow address pits can be easily and well formed. can. Further, the width of the guide groove can be freely changed by changing the interval between the beam spots 18 and 19, and the diameter of the beam spot can be changed by changing the combination of the focal lengths of the third lens 12 and the fourth lens 13 as necessary. You can change it. The interval between the beam spots 18 and 19 can be easily changed by changing the frequency of the ultrasonic waves that drive the acousto-optic light modulator 9 and by changing the separation angle between the third beam 10 and the fourth beam 11.

The ratio of the intensities of the beam spots 18 and 19 can be changed by changing the amplitude of the ultrasonic waves that drive the acousto-optic optical modulator 9.

Moreover, since the beam spot is relatively small, the light intensity per unit area can be increased, and the intensity of the laser beam can be used efficiently.

Similarly to the second beam 4, an acousto-optic optical modulator is installed after the optical modulator 5 on the optical path of the first beam 3, and the first beam is split into two and incident on the recording lens 15. By doing so, the address pit may be recorded with two beam spots. In this case, the same effect as the guide groove can be obtained for the address pit as well.

Effects of the Invention As described above, according to the optical disc master manufacturing apparatus of the present invention, by recording guide grooves or address pits with two beams each, relatively wide guide grooves or address pits can be easily formed in good condition. can be formed. Further, the width can be changed simply by electrically changing the drive signal of the acousto-optic optical modulator, and there is no need for troublesome optical axis adjustment.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an optical disk master manufacturing apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing the arrangement of beam spots on the same recording surface, and FIG. 3 is a block diagram showing the configuration of a conventional optical disk master manufacturing apparatus. The block diagram shown in FIG. 4 is a diagram showing the arrangement of beam spots on the same recording surface. 1... Laser light source, 5, 6... Light modulator, 9... Acousto-optic optical modulator, 1o...
...○-order diffracted light, 11...1st-order diffracted light, 15.
...recording lens, 16...recording medium, 2
1.22, 23, 24.25...mirror

Claims (2)

[Claims] (1) In an optical disk master production device that focuses a laser beam emitted from a laser light source onto the recording surface of a recording medium, records information, and produces an optical disk master, the laser beam emitted from the laser light source is split into two. a means for dividing the laser beam; a means for independently modulating the intensity of each of the divided laser beams;
means for splitting at least one of the intensity-modulated laser beams into two; and means for arranging all of the resulting laser beams on a recording surface in a straight line perpendicular to the rotational direction of the recording medium. An optical disc master production device comprising: (2) The optical disc master manufacturing apparatus according to claim 1, characterized in that an acousto-optic element that utilizes Plagg diffraction is used as a means for splitting the intensity-modulated laser beam.