JPS63157340A - Magneto-optical recording/reproducing device - Google Patents

Abstract

PURPOSE:To check data in a simple constitution by performing the recording/ erasing jobs of a magnetic disk with the 0-degree light separated by a diffraction grating and reproducing signals with the diffracted light following the 0-degree light out of the + or -1-degree light. CONSTITUTION:The light delivered from a laser light source 1 is turned into parallel luminous fluxes by a collimator lens 2 and made incident on a disk via a diffraction grating 17 and an objective lens 6. The reflected light sent from the disk is led to a 6-split photodetector 13 via a beam splitter 4 and an astigmatic optical system 11. The laser flux is separated into the 0-degree light and the + or -1-degree light by the grating 17. The 0-degree light 15 is used for recording/erasing jobs and the signals are reproduced by the diffracted light 16b following the 0-degree light out of + or -1-degree beams 16a and 16b. Thus data can easily be checked in real time.

Description

[Detailed Description of the Invention] [Summary] This is a magneto-optical recording and reproducing device that records and reproduces light from a central spot by dividing light from a single light source with a diffraction grating.
Data can be checked in real time by performing erasing and reproducing with the one of the ±1st order beams located after the recording/erasing spot.

[Industrial application field]

The present invention relates to a so-called magneto-optical recording/reproducing device that optically records information on a magneto-optical medium.

A magneto-optical recording/reproducing device has a large capacity storage,
In addition to its features of non-contact recording and medium exchange, it is also rewritable, so the market is rapidly expanding from the field of recording and reproducing image information to those capable of recording and reproducing code information for computers. For this reason, research and
Development is happening everywhere.

[Prior art]

A conventional magneto-optical recording device is shown in FIG. To explain with reference to the figure, the diverging light from the semiconductor laser 1 becomes a parallel light beam by the collimating lens 2, passes through the circular correction prism 3 and the first beam splitter 4, and enters the objective lens 6 by the reflecting mirror 5. In order to irradiate a minute focused spot onto a predetermined track on a magneto-optical disk (not shown in this figure), the objective lens is usually controllable in two axes: focus and track direction. The reflected light from the magneto-optical disk travels in the same optical path as the incident light and reaches the first beam splitter 4. The light beam reflected by the first beam splitter is separated by the second beam splitter 7 into transmitted light and reflected light.

The transmitted light of the second beam splitter passes through, for example, an astigmatism optical system 11 and enters a photodetector 12 for detecting focus and tracking error signals.

The focus, error signal detection method, and track error signal detection method are an astigmatism method and a push-pull method, respectively, but they are both well-known methods and are not particularly illustrated because they are not directly related to this case.

The light beam reflected by the second beam splitter 7 is used for magneto-optical signal detection by rotating its polarization direction by 456 degrees by a 1/2λ plate 8, and then passes through the condenser lens 10 to the polarization beam splitter 7.
The transmitted light and the reflected light are separated by the filter 9 and enter the respective detectors 13a and 13b. The magneto-optical signal is detected from the differential outputs of the two photodetectors 13a and 13b.

[Problem that the invention seeks to solve]

In the above-mentioned conventional magneto-optical recording device, recording, reproduction, and erasing are all performed in one spot. Therefore, in fields where higher error rates are required, such as in the case of external storage devices for computers, the performance There was a problem of decline. This is because, as with optical discs in general, there are many defects in the medium itself, and it is necessary to check the recorded data after recording.

The conventional configuration required two rotations, one rotation for recording and one rotation for checking. To solve this problem, a so-called two-beam optical head, which has two beams for recording/erasing and reproducing, has been considered, but this has problems such as the accuracy of positional deviation between the two spots and an increase in the number of optical components. It arises.

The present invention was created in view of the above points, and an object of the present invention is to provide a magneto-optical recording and reproducing apparatus that is simple in structure without a cost amplifier and is capable of real-time data checking.

[Means for solving problems]

FIG. 1 is a principle diagram of the present invention, 15.16a.

16b is the spot when the light beam separated by the diffraction grating is focused on the magneto-optical disk by the objective lens, and 15 is the spot of O.
The order lights 16a and 16b are ±1st-order diffracted lights.

Here, spot 15 becomes a recording/erasing spot, and in the case of the disk traveling direction as shown in FIG. 1, the latter spot 16b becomes a reproducing spot.

However, 14 indicates a guide groove on the disk.

[For production]

In the present invention, since the light beam from one light source is separated into one for recording/erasing and one for reproduction using a diffraction grating, problems such as positional deviation between each spot and an increase in the number of optical parts do not occur. This enables stable recording and playback.

〔Example〕 FIG. 2 is a diagram showing an embodiment of the present invention.

As shown in FIG. 2, this embodiment includes a semiconductor laser 1 as a light source, a collimating lens 2 that converts the light emitted from the semiconductor laser 1 into a parallel light beam, and a collimator lens 2 that converts the parallel light beam into zero-order light and ±first-order light. A diffraction grating 17 that separates the light, a circular correction prism 3, a beam splinter 4, a mirror 5 that guides the light to a magneto-optical disk (not shown), an objective lens 6, and a photodetector for the reflected light from the magneto-optical disk. 4< 1/2 wavelength plate 11a
, a convex lens Ilb, and a cylindrical lens Ilc.
6-divided photodetector 13b.

In this way, this embodiment is the same as the conventional example in that the light emitted from the semiconductor laser 1 is made into a parallel beam and goes to the tunamono lens through the beam splinter after correcting the circularity, but the difference is that the collimating lens 2 and the parallel beam Diffraction grating 1 between circular correction prisms 3
7 has been inserted. This diffraction grating separates the light beam from the semiconductor laser into 0th-order light and ±1st-order light.

Further, the separated reflected light from the beam splitter 4 directly passes through the astigmatism optical system 11 and the polarizing beam splitter 9, and enters each of the photodetectors 13a and 13b, so that the optical system can be made into a series. ing.

In this configuration, servo signals and information are reproduced from the same photodetector output. This situation is shown in FIG.

The output of each photodetector is divided into four parts by a differential amplifier 18.
A focus error signal is obtained by passing through the differential amplifier 19, a track error signal is obtained from the difference between both sides by the differential amplifier 19, and a magneto-optical information signal is obtained by passing the output of the rear spot through the differential amplifier 20. Also, as can be seen from the figure, since the difference between each output is taken as an information signal, the waveform during recording becomes an in-phase component and is removed, and only the change in polarization state is output from the amplifier 20 as a magneto-optical signal. Detected.

〔Effect of the invention〕

As described above, according to the present invention, the light beam from one light source is divided by a diffraction grating to obtain a spot for recording/erasing and a spot for reproducing, thereby configuring an apparatus capable of checking data in real time. However, it is possible to provide a magneto-optical recording and reproducing apparatus that does not cause problems such as positional deviation between spots and cost increases due to an increase in the number of optical elements, and is extremely useful in practice.

[Brief explanation of the drawing]

Fig. 1 is a diagram for explaining the principle of the magneto-optical recording/reproducing device of the present invention, Fig. 2 is a diagram showing an embodiment of the invention, and Fig. 3 is a servo signal by a photodetector in an embodiment of the present invention. FIG. 4 is a diagram showing a conventional magneto-optical recording and reproducing apparatus. 1 and 2, 1 is a semiconductor laser, 2 is a collimating lens, 3 is a circular correction prism, 4 is a beam splitter, 5 is a mirror, 6 is an objective lens, 9 is a polarizing beam splitter, and 11 is a polarizing beam splitter. Astigmatism optical system, 13a and 13b are photodetectors, 14 is a disk guide groove, 15 is 0th order light separated by a diffraction grating, 16a and 16b are ±1st order lights separated by a diffraction grating, 17
is a diffraction grating, and 18, 19, and 20 are differential amplifiers. FIG. 15 for explaining the principle of the magneto-optical recording and reproducing device of the present invention...O-order light 16a and 16b separated by a diffraction grating
...±1st-order light separated by a diffraction grating Figure 2 shows an embodiment of the present invention.

Claims (1)

[Claims] 1. A magneto-optical recording and reproducing device for optically recording and reproducing information, comprising: a semiconductor laser (1) as a light source; and a divergent beam emitted from the semiconductor laser (1) into a parallel beam. a diffraction grating (17) that separates the parallel light beam into 0th-order light and ±1st-order light; and an objective lens (6) that focuses the light beam onto a magneto-optical disk.
), and a beam splitter () disposed between the objective lens (6) and the diffraction grating (17), which separates the light flux from the light source toward the magneto-optical disk and the reflected light from the magneto-optical disk to a signal detection system. 4), an astigmatism optical system (11) that transmits the reflected light from the beam splitter (4), and 1/2λ that rotates the direction of the polarization plane of the reflected light by 45°.
plate (8), and the reflected light is divided into 2
a polarizing beam splitter (9) that separates into two photodetectors; a first six-split photodetector (13a) that receives transmitted light from the polarized beam splitter (9); and a second photodetector that receives reflected light. It is equipped with a 6-split photodetector (13b), and records and erases using the 0th order light separated by the diffraction grating 17,
A magneto-optical recording and reproducing device characterized in that a signal is reproduced using diffracted light disposed after the 0th-order light of the ±1st-order light.