JPS60179959A - Photomagnetic disk device - Google Patents

Abstract

PURPOSE:To improve S/N of a data signal by rotating slightly the polarizing direction of the light projected to a photomagnetic disk from a light source toward the polarizing direction of the light going toward a servo sensor and therefore eliminating the interference between the data signal and the servo signal. CONSTITUTION:Laser light given from a laser light source 1 is projected to a photoelectric disk 6 through a half mirror 3, and this reflected light is rotated with its polarized surface by a Kerr revolving angle +thetak or -thetak according to the magnetizing direction of the disk 6. Then the reflected light is reflected by the mirror 3 and separated by a polarized beam splitter 13. Then the P polarized component is made incident on a data sensor 12 with the S polarized component projected to a servo sensor 10 respectively. In such a way, no interference occurs between the data and servo signals since both signals are separated from each other. Furthermore a large output is obtained for the servo signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to improving the writing and reading characteristics of an optical head of a magneto-optical disk device.

[Conventional example]

In conventional magneto-optical disk drives, focus, track, and king servo signals are obtained by inputting light that has passed through an analyzer into a sensor. This type of device has a problem in that the data signal interferes with the servo signal, and also has the disadvantage that the servo light intensity is low. As an improvement on this, there is a device that uses a half mirror to separate data light and servo light, as shown in FIG.

In the figure, 1 is a laser light source, 2 is a polarizer, 3 is a half mirror, 14 is a mirror, 5 is a lens, 6 is a magneto-optical disk, 7 is a half mirror, 18 is a collimator lens, 9 is a cylindrical lens, 1o is a servo sensor , 11 is an analyzer, and 12 is a data sensor.

In such a device, the laser beam #1 is polarized by a polarizer 2, transmitted through a half mirror 3, bent by a mirror 4, condensed by a lens 5, and then directed to a magneto-optical 14 disk 6. Projected. After the reflected light from the magneto-optical disk 6 returns along the same path as the projected light, it is reflected by the half mirror 5, and the light is split into two by the half mirror 7. One of the two halves of the light passes through a collimator lens 8 and a cylindrical lens 9, and is projected onto a servo sensor 10. The other light is
It passes through the analyzer 11 and is projected onto the data sensor 121C.

As described above, the data signal and the servo signal are obtained separately, and there is no possibility that the data signal will interfere with the servo signal.

However, in such a device, since the light is doubled, the data signal becomes smaller and the S/N ratio deteriorates. Another disadvantage is that the optical system becomes complicated.

The present invention solves this problem.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a magneto-optical disk device that can obtain a servo signal that does not interfere with a data signal and a data signal with a simple optical system configuration, and can also provide a data signal with a good signal-to-noise ratio.

[Structure of the invention]

To achieve this purpose, we use a magneto-optical disk whose tip is projected from a sharp light source, a polarized beam currant that separates the light from the magneto-optical disk into light directed to the servo sensor and light directed to the data sensor. A magneto-optical disk device is constructed in which the polarization direction of light projected from the light source onto the magneto-optical disk is slightly rotated from the polarization direction of light directed toward the servo sensor.

Examples will be described below.

〔Example〕

FIG. 2 is an explanatory diagram of the configuration of an embodiment of the present invention.

In the figure, the same symbols as in FIG. 1 indicate the same functions.

Hereinafter, only the different parts of FIG. 1 will be explained.

13 is a servo sensor 10 that detects the light from the half mirror 3.
and a polarizing beam splitter that doubles the data sensor 12. 14 is a servo amplifier that amplifies the signal of the servo sensor, and the amplified signal is sent to the tracking actuator 15 and the tracking actuator 16 attached to the condenser lens 5. This is a data preamplifier that amplifies the signal.The laser tip of the laser light source 1, the polarized beam splitter, and the
It is composed of parallel light having a polarization direction rotated by Δθ8 from the S-polarization direction with respect to the reflecting surface.

In the above configuration, the laser beam of Le Kogen 1 is as follows:
The light passes through the half mirror 3, is focused by the condenser lens 5, and is projected onto the magneto-optical desk 6. The light reflected and returned from the magneto-optical disk 6 has a plane of polarization of Kerr rotator 〇 or -θK (for example, 0) depending on the magnetization direction K of the magneto-optical disk (leftward or rightward in FIG. .3°) is rotating. The reflected light is reflected by the half mirror 3 and projected onto the polarizing beam splitter 13. In the polarizing beam splitter 13, most of the P-polarized light is transmitted and the S-polarized light is transmitted.
Since the polarized light is reflected, the P-polarized light component is incident on the data sensor 12, and the S-polarized light component is projected on the servo sensor IOK. The electric field directions of the laser light from the laser light source 1 and the light incident on the polarized beam splitter 13 are as shown in Figure 3.

As can be seen from Fig. 3, the light of the S direction component is sent to the servo sensor 10, and the difference between the car rotation angles of 10 and -0 is negligible, and ■ a large signal is sent. .

On the other hand, the data sensor 12 is connected to the company car rotating inner
In contrast, light of the P-direction component whose amplitude changes greatly is sent. The light directed toward the servo sensor 1o passes through the collimator lens 8 and the cylindrical lens 9, and in this case is received by the servo sensor 1o, which is a multi-segment sensor, and is amplified by the servo amplifier 14 to generate a focus error signal and a tracking error. This becomes a signal, operates the focus actuator 15 and the tracking actuator 16, and controls the condenser lens 5.

As a result of the above, (1) the data signal and the servo signal are obtained separately, so there is no possibility that the data signal will interfere with the servo signal. (2) Also, a large output can be obtained as a servo signal. ■Polarizing beam splitter 13
Since this is used, an analyzer is not required and the configuration of the optical system is simplified.

(2) Even if the light is used separately as a servo signal, a signal without deterioration of the signal-to-noise ratio of the data signal can be obtained.

FIG. 4 is a configuration explanatory diagram of another embodiment of the present invention.

In this embodiment, the condenser lens 5 is replaced with the magneto-optical disk 6.
Mr. L installed two of these, and they were configured to be of a transparent type.

In the above embodiment, it was explained that the polarization direction of the laser light from the laser light source 1 is composed of parallel light having a polarization direction rotated by Δθ8 from the S-polarization direction. It may be composed of parallel light having a polarization direction rotated by ΔθS from P-polarized light. In this case, it is sufficient to project the transmitted light of the polarizing beam splitter 13 onto the servo sensor 10 and the reflected light onto the data sensor 12.

In addition, the polarization of the laser beam from the source 1 of the sea 4 is directed accurately toward the direction of the mirror 3 and the magneto-optical disk 60, toward the direction of the sky, or in the radial direction, and the polarizing beam splitter 13
may be rotated by Δθ8 with respect to this.

Furthermore, instead of the half mirror 70, a polarizing beam splitter 13 may be used which has a slightly poor extinction ratio for the light directed toward the sensor 10 and 12. Improved light efficiency and half mirror
In order to correct the phase shift with respect to the P-polarized light wave or the S-polarized light wave such as 7, etc., a phase adjustment element such as a plate may be inserted into the light entering the 1-polarized beam λ-splitter 13.

In the tracking error detection method according to the above, when the data sensor section 10 is multi-divided, the result is K.

In addition, when the laser light source 1 is a semiconductor laser or the like and the laser light itself has polarization, the polarizer 2 is
Of course, it is not necessary.

[Action and effect of the invention]

As explained above, the present invention includes a polarizing beam splitter that separates light from a magneto-optical disk into light directed to a servo sensor and light directed to a data sensor, and projects the light from a light source onto the magneto-optical disk. A magneto-optical disk device was constructed in which the polarization direction of light was slightly rotated from the polarization direction of light directed toward a servo sensor.

As a result, large outputs of data signals and servo signals can be obtained. ■Since a polarized beam splitter is used, an analyzer is not required and the structure of the optical system is simplified. (2) A servo signal that does not deteriorate the S/N ratio of the data signal even if the light is used separately can be obtained.

Therefore, according to the present invention, it is possible to realize a magneto-optical disk device in which a servo signal that does not interfere with a data signal can be obtained and a data signal with a good S/N ratio can be obtained with a simple optical system configuration. .

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of the configuration of a conventional example commonly used in the past, Fig. 2 is an explanatory diagram of the configuration of an embodiment of the present invention, Fig. 3 is an explanatory diagram of the operation of Fig. 2, and Fig. 4 is an explanatory diagram of the present invention. FIG. 2 is a configuration explanatory diagram of another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1...Laser light source, 2...Polarizer, 3...Half mirror-14...Mirror, 5...-Lens, 6...
Magneto-optical desk, 8... Collimator lens, 9... Cylindrical lens, 10... Servo sensor, 12
... Data sensor, 13... Beam splitter-114... Servo amplifier, 15... Focus actuator, 16... Tracking actuator, 17... Data preamplifier.

Claims (1)

[Claims] A magneto-optical disk onto which polarized light from a light source is projected, and a polarizing beam splitter that separates the light from the magneto-optical disk into light directed to a servo sensor and light directed to a data sensor.
A magneto-optical disk device comprising: a magneto-optical disk device in which the direction of polarization of light projected from the light source onto the magneto-optical disk is slightly rotated from the direction of polarization of light directed toward a servo sensor.