JPS60106031A - Preprocessor of optical recording medium - Google Patents

Abstract

PURPOSE:To change at a high speed the entire surface of an optical disk into a state of a high optical constant by using an optical system which leads the light radiated from a light source onto an optical recording medium in a fixed form and then shifting the irradiating position of the light on the recording medium. CONSTITUTION:The light is dispersed in both the tangent and radius directions of a disk by means of cylindrical lenses 7 and 8. The dispersed light having a diameter larger than the aperture diameter of an objective lens 9 is obtained in the radius direction of the disk, and the peripheral light is cut off by the aperture of the lens 9. While the dispersed light of the tangent direction of the disk has a diameter smaller than the aperture diameter of the lens 9. For the distance between the lens 9 and the disk 5, the focus servo is applied by a control means 10 so that the recordingsurface of the disk is set at the focal position of parallel beams. It is possible to vary the sizes and distribution of the spots on the disk by changing both the focal distance and the focal position of the lenses 7 and 8.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is a method for recording or recording by changing optical constants before and after recording.
The present invention relates to a preprocessing device for setting the initial reflectance or initial transmittance of an optical disc to a certain level in advance in an erasing type optical recording medium (optical disc).

Conventional Structures and Problems There are two main types of optical disks that have been developed so far: those that change the reflectance by forming holes or bubbles in the recording medium by irradiating it with laser light, etc.; There are two types of recording media, one in which the optical constants such as n and ni are changed while the shape of the recording medium is unchanged, and the resulting change in reflectance or transmittance is utilized.

Among these, optical disk recording media that belong to the latter category include those that utilize phase transformation between an amorphous state and a crystalline state, such as a chalcogen-based glass thin film, or Teox (
It is well known that changes in the crystallinity and particle size of small crystalline particles in a thin film, such as a thin film centered on 0(x(2)), are caused by changes in the optical constant from large to small. ,
Alternatively, any direction from the small state to the large state can be used as an information recording means or erasing means.

However, in general, when forming these thin films,
Since it is a state in which the optical constant is relatively small, when using a change in the optical constant from a dog state to a small state as the recording direction, it is necessary to first change the optical constant of the thin film to a dog state. is necessary. Changing the optical constant from a small state to a large state is done by heating a thin film and gradually cooling it. The optical constant can be changed from a large state to a small state by heating the thin film and rapidly cooling it.

Therefore, when recording and erasing is performed using a player on a thin film that can be recorded and erased, the laser beam is focused on a small spot P of about 1 μm as shown in Fig. 1, and the thin film is The optical constants of thin films can be reduced by heating and rapidly cooling them in a shorter time.

Information is recorded on a long and narrow spot P with a length of about 10 μm.
' can be erased by increasing the optical constant of the thin film by heating and slowly cooling it for a longer time.

By the way, when forming a thin film, it is possible to change the optical constant from a small state to a dog state in advance by using the above-mentioned elongated spot (called an erasing spot), but this can only process one track at a time. It is time consuming and not very productive.

However, if the thin film is placed in the open with the substrate and heated, problems such as deformation of the substrate will occur.

Purpose of the Invention The present invention is a pretreatment device for bringing optical recording media, especially erasable recording media, from a state where the optical constants are small when forming them to a state where the optical constants are large enough to enable recording. The purpose of this invention is to obtain a pretreatment device for optical recording media that can rapidly change the entire surface of an optical disk to a state with high optical constants by irradiating a wide range of high-power, continuous-output laser beams onto the disk. do.

Structure of the Invention In order to achieve the above object, the present invention provides a radiation light source, an optical system that guides the radiation light from the radiation light source in a fixed shape onto an optical recording medium, and a radiation position of the radiation light on the recording medium. ,
This is a preprocessing device for an optical recording medium, which includes a recording medium or a moving means for relatively moving the recording medium by moving the radiation light.

DESCRIPTION OF EMBODIMENTS The present invention will be described in detail below with reference to the drawings. In FIG. 2, 1 is an Ar laser with an output of 1W to 4W. Depending on the lens 2, the diameter of the laser beam is 30 μηl to 60 μηl.
The rotating disk 6 is irradiated with an aperture of .mu.nl.

Reference numeral 4 denotes a moving stage that moves the irradiation position on the radius of the disk. The disk 5 is rotated by a motor 6.

Due to the heat irradiated onto the disk by the laser beam, the recording thin film on the disk changes from a state where the optical constant is small to a state where the optical constant is small. In order to keep the irradiation conditions constant on the inner and outer circumferences of the disk, it is necessary to keep the linear velocity of one rotation and the feed pinch constant. For this purpose, the rotation speed and feed rate of the motor were made inversely proportional to the radius of the irradiation position on the disk. The reason for this will be explained below. Let V be the linear velocity and ω be the rotational angular velocity.

v = rω. Here, r is the radius of the irradiation position on the disk. Therefore, in order to keep the linear velocity V constant, it is sufficient to make ω-E and the rotational angular velocity of the motor inversely proportional to r. Similarly, the feed pitch p is p-Σ1; where the feed speed is U and the motor rotation speed is 2πω. ω=
7, so it becomes "" 2yrv, which becomes u-□.

Therefore, in order to keep V and p constant, the feed rate U should be made inversely proportional to r.

When the linear velocity of rotation is IQm/B, the particle density of the irradiated light is on the order of 1 mVY/μm'. Therefore, the diameter is 60μ? When irradiating +1 spots,
The total power required is 60μ in diameter? Assuming a uniform power distribution within the IZ circle, a total laser power of approximately 3.6 W is required.

By the way, in the method of the first embodiment, the shape of the spot on the disk is circular, and the intensity distribution is a Gaussian distribution with the maximum power at the center. Therefore.

Unevenness in optical constants may occur on the disk.

This problem was solved by the method of the second embodiment, in which the shape of the irradiated light was configured to have a relatively uniform intensity distribution in the radial direction of the disk. As shown in FIG. 3, the cylindrical lens 8 generates diverging light in the radial and tangential directions of the disk. In the radial direction of the disk, the divergent light is larger than the aperture diameter of the objective lens 9, and the aperture of the objective lens 9 blocks out peripheral light. In the tangential direction of the disk, the aperture can be made smaller than the aperture of the objective lens 9. Therefore, the intensity distribution of the incident light on the objective lens 9 is as shown in FIG. On the other hand, focus servo is applied to the distance between the objective lens 9 and the disk 5 by the control means 1° so that the recording surface on the disk is at the focal point of the parallel light, as shown in FIG. Then, the incident light that has become diverging light due to the cylindrical lens is condensed at a location far from the disk 5, so that it becomes an optical image of a constant size on the disk. At this time, the intensity distribution of the light on the disk is approximately uniform in the radial direction and has a Gaussian distribution in the tangential direction, as shown in FIG. By changing the focal length and position of the cylindrical lens used, the size and distribution of the spot on the disk can be changed. The shape of the spot can also be changed by changing the distance between the objective lens and the disk.

In order to determine the optimal spot shape, it is necessary to consider many parameters. One parameter is the characteristics of the recording medium. As a recording medium, temperature changes in optical constants,
There are various factors such as rate of change and thermal conductivity, and the optimal one differs depending on the use of the final product. In other words, even if we consider the necessary linear velocity for recording and reproduction, real-time recording of digital video information requires a linear velocity of about 25 m/s.
For data recording, etc., there are speeds of about 2 m/s. Other parameters include disk size, S/N, required processing time, etc.

The optimum size of the spot in the tangential direction is when the linear speed is 10 m.
/s, it varies from about 5 μm to 60 μm depending on the difficulty of changing the optical constants of the recording medium. Also, the larger the spot size in the radial direction, the larger the feed pitch can be, and therefore the faster the processing time, but depending on the relationship between the required power density and laser power, it is possible to have a spot size of about 6 μm to 100 μm. Also, the shorter the feed pitch is compared to the size of the spot in the radial direction, the more uniformly the optical constant can be made over the entire area, but this also has to do with the processing time.

In this example, a 4W argon laser was used as the radiation light source. Also, the focus servo is He −
The Ne laser beam is incident on the objective lens at a position shifted from the optical axis, and a two-split photodetector detects that a change in the distance between the recording surface and the objective lens results in a shift in the optical path of the reflected light, and an error signal is detected. And so. This is exactly the same as the well-known focus servo in that this error signal is amplified and the phase compensated signal is applied to a focus actuator that moves the objective lens up and down.

In this example, the reflected light of the He-Ne laser,
Alternatively, the intensity of the transmitted light is detected with a photodetector, and this He-N
o The reflectance and transmittance of the recording surface were measured by measuring the ratio to the intensity of the reflected light from the beam splitter attached to the emission part of the laser. Since the power drift of the He-N@laser itself is used as the denominator, it does not become an error in the measurement of reflectance or transmittance.

For recording media, it is better to use a laser beam to first reduce the optical constants and then increase the optical constants, rather than simply increasing the optical constants using a laser beam after vapor deposition. There are some things that are good, and some things that it is better to repeat changing the optical constant from a large state to a small state several times.

For this purpose, as shown in Figure 6, before spot b, which is used to make the optical constant large, is heated and rapidly cooled in a short and tangential direction to make the optical constant small. You can add spots where you can.

FIG. 7 is a block diagram of the main optical system in the third embodiment of the present invention, and shows an optical system that can obtain a spot shape as shown in FIG. 6. Spora) a is obtained by making a parallel beam enter the objective lens 9 only in the tangential direction of the track, and placing the recording medium at the focal point of the objective lens.

The cylindrical lenses 13 and 16 provide wide parallel light. The cylindrical lens 14 causes the light to diverge in the radial direction of the track. 12 is a λ/2 plate which rotates the polarization direction of the light from the Ar laser 1 by 90 degrees and combines the two lights by a polarizing prism 16. 17 is a dichroic mirror, H
It reflects the +333 rlm wavelength of the e-N e laser and transmits the 470-530 nm wavelength light of the Ax laser.

By making the two lights of the Ar laser and the light of the He-N e laser enter the objective lens 9 at an angle, the spot positions can be separated as shown in FIG. The distance between each spot is represented by the product of the inclination angle of their respective incident optical axes and the focal length of the objective lens 9.

By adopting the arrangement as shown in FIG. 6, it becomes possible to measure the reflectance and transmittance after processing to increase the optical constant using the He--Ne laser beam.

FIG. 8 shows a spot shape monitoring optical system, in which a small portion of the light incident on the objective lens and the reflected light from the recording medium 6 are separated by a beam splitter 18, and the spot shape can be monitored by a microscope 21. Also, when a part of the reflected light from the recording medium 5 is reflected by the mirror 19 and monitored, the focus state is adjusted by adjusting the focus position so that the reflected light from the spot 7)a is also narrowed down to a small extent in the tangential direction of the track. can be matched correctly.

Effects of the Invention According to the present invention, in the process of bringing an optical disk recording medium, especially an erasable recording medium, from a state of low optical constants during formation to a state of high optical constants that allows recording, It is possible to obtain an optical recording medium preprocessing device that can perform high-speed and uniform processing, and its industrial utility value is large.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the shape of a spot during recording and erasing of an erasable optical disc, and FIGS. 2 and 3 are configuration diagrams of the first and second embodiments of the preprocessing apparatus of the present invention, respectively. , FIGS. 4 and 6 are explanatory diagrams of the second and third embodiments of the present invention,
FIG. 6, FIG. 7, and FIG. 8 are configuration diagrams of a third embodiment of the present invention. 1... Argon laser, 2... Lens, 3.19... Mirror, 4... Moving table, 5... Recording medium, 6... Motor,
7, 8, 13, 14, 16... Cylindrical lens, 9
...Objective lens, 10...Focus actuator, 11.18...Heams 9
liter, 12...λ/2 plate, 16...
Polarizing prism, 17... Dichroic mirror, 20... Objective lens for monitor, 21...
...Monitoring microscope. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Plane P' Fig. 2 Ogi'43 Cause 5 Fig. 6 Fig. 7 Fig. 8

Claims (1)

[Claims] (1) Information is recorded by changing the reflectance from R1 to R2 or the transmittance from T to T2 by irradiating synchrotron radiation with a higher intensity than the level, and Reflectance R05 or transmittance T is the initial state at the time of formation of an optical recording medium that can be irradiated with very low radiation light and read information from changes in the intensity of reflected or transmitted light. , the reflectance R
1, or a pre-processing device for making the transmittance T1, which comprises a radiation source, an optical system that guides the first radiation from the radiation source onto the optical recording medium, and a radiation source for the first radiation. moving means for moving the irradiation position on the optical recording medium relatively by moving the optical recording medium or the first radiation light, in the direction of the relative movement of the first radiation light; A preprocessing device for an optical recording medium having a length of 5 μm or more in full width at half maximum, and a length in a direction perpendicular to the direction of relative movement of 6 μm or more in full width at half maximum. (2) The preprocessing device for an optical recording medium according to claim 1, wherein the moving linear velocity of the optical recording medium at the irradiation position of the first radiation light is substantially constant. (3) The preprocessing device for an optical recording medium according to claim 1, wherein the feeding pitch of the optical recording medium at the irradiation position of the first radiation light is substantially constant. (4) Pretreatment of the optical recording body according to claim 1, in which the feeding pitch of the recording medium is made smaller than the length in the direction perpendicular to the relative movement direction at the irradiation position of the first radiation light. Device. (6) In an orthogonal coordinate system x-y-z with the optical axis direction of the first synchrotron radiation as the Z axis, the first synchrotron radiation is a first unidirectional lens that has a lens action only in the X direction, 2. The preprocessing device for an optical recording medium according to claim 1, wherein the light passes through a second unidirectional lens having a lens action in only one direction, and is focused onto the optical recording medium by a third lens. (6) Part of the first radiation light is separated, or the second radiation light from another radiation source is passed through a third lens and irradiated onto the optical recording medium, and this reflected light is extracted from the a focus error signal detection means for keeping the distance between the third lens and the optical recording medium constant; an electromagnetic driving means for moving the third lens in a direction substantially perpendicular to the optical recording medium; 2. The optical recording medium preprocessing device according to claim 1, further comprising a servo circuit for driving said electromagnetic drive means based on a focus error signal. (7) The light according to claim 1, which detects the intensity of the emitted light or the reflected light or transmitted light of the second emitted light, and makes it possible to measure the reflectance or transmittance of the optical recording medium. Pre-processing device for recording media. (8) The length in the relative movement direction at the irradiation position is 3η
The pre-processing device for an optical recording medium according to claim 1, which has a third emitted light of Lμ or less. (9) The preprocessing device for an optical recording medium according to claim 1, wherein the length of the third radiation light in the direction perpendicular to the relative moving direction at the irradiation position is 5 μm or more. (10) A unidirectional beam expander system placed so that the third synchrotron radiation becomes parallel light with a constant beam diameter only in the X direction, and a fourth unidirectional beam expander system in the Y direction. 2. The preprocessing device for an optical recording medium according to claim 1, wherein the optical recording medium is positioned at the focal point of the parallel light that passes through a lens and is focused by the third lens. (11) first and second synchrotron radiation, or first 9M2,
2. The preprocessing device for an optical recording medium according to claim 1, wherein the third radiation light and the third emitted light are arranged in a column in a direction of movement relative to each other on the optical recording medium. (12) A beam splitter placed in the path of any one of the first, second, and third emitted light to partially separate the incident light or the reflected light from the optical recording medium; and the beam splitter. By light separated by. 2. The optical recording medium preprocessing apparatus according to claim 1, further comprising means for monitoring the shape of the emitted light on the optical recording medium.