JPS628347A - Optomagnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To attain miniaturization by using a polarized beam splitter comprising a triangle prism, a collimated plate or a wedge plate, a polarized film and a full reflection film as an analyzer. CONSTITUTION:The polarized film 12 of a polarized beam splitter 9 is a vapor- deposition film reflecting abnormal polarized light and transmitting a normal polarized light and the full reflection film 14 is a vapor-deposition film reflecting the normal polarized light. Through the constitution above, the plate thickness of the collimated plate 13 is brought into a prescribed thickness to provide a prescribed separation width to the abnormally polarized light and the normal polarized light for separation. In this example, a right angle prism 11 is used but a triangle prism with an optional angle (not necessarily right angle) is used to change the irradiation direction and the edge of the triangle prism at which no light is transmitted can be cut off. Further, the wedge plate is used in place of the collimated plate 13 to change the separation width between the abnormally polarized light and the normally polarized light.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to magneto-optical recording and reproducing in which information is recorded, reproduced, and erased by irradiating an rIfi thin film recording medium with a light beam such as a laser beam. It is related to the device.

[Conventional technology]

2. Description of the Related Art Recently, magneto-optical recording and reproducing devices that use a magnetic thin film as a recording medium and use laser light to record, reproduce, and erase information have been actively developed.

FIG. 4 is a configuration diagram illustrating a conventional magneto-optical recording/reproducing apparatus of this type. In the figure, 1 is a laser light source, 2 is a collimating lens, 3 is a polarizer, 4 is a half mirror, 15 is an objective lens, 6 is a recording medium, 7 is a 1/2 wavelength plate, 21 is an analyzer,
22 is a lens, and 23 is a detector.

Light from a laser light source 1 is made into a parallel beam through a collimating lens 2, linearly polarized by a polarizer 3 such as a polarizing beam splitter, and incident on a half mirror 4, and further focused by an objective lens 5 to be directed onto a recording medium 6. irradiate. The light reflected by the recording medium 6 is focused by the objective lens 5, reflected by the half mirror 4, passes through the 1/2 wavelength plate 7, and passes through the analyzer 21, which is a cube-shaped polarizing beam splitter.
The light is separated into two directions, each focused by a lens 22, and incident on each detector 23.

The plane of polarization of the reflected light of the linearly polarized laser beam irradiated onto the recording medium 6 rotates due to the Kerr effect according to the direction of magnetization, so the output of the detector 23 changes depending on the direction of magnetization. . This circuit can read information from the recording medium 6 by using two detectors 23 in a differential configuration to cancel medium noise.

[Problem that the invention seeks to solve]

The above-mentioned conventional magneto-optical recording/reproducing device uses a cube-shaped polarizing beam splitter (21) as an analyzer to separate the beam in a 90° direction, focuses the separated ends with a lens, and sends the beam to the detector 23. Since the light is incident, the optical system becomes large and the number of parts increases, which is a drawback.

An object of the present invention is to provide a magneto-optical recording/reproducing device which eliminates such drawbacks and has a simplified and compact configuration.

[Means for solving the problem j] The configuration of the present invention is such that a linearly polarized light beam is irradiated onto a magneto-optical recording medium, and the linearly polarized light reflected from the recording medium is incident on an objective lens and then passed through an analyzer. In the magneto-optical recording/reproducing device, the analyzer is composed of a triangular prism and a parallel plane plate or a wedge plate attached to the slope of the triangular prism. a polarizing film provided on the interface between the triangular prism and the plate to reflect abnormally polarized light and transmit normally open light; and a total reflection film provided on the other surface of the plate to reflect normally open light. It is characterized by consisting of a polarizing beam splitter with a

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of a magneto-optical recording/reproducing apparatus according to an embodiment of the present invention. In the figure, 1 is a laser light source, 2 is a collimating lens, 3 is a polarizer, 4 is a half mirror, 15 is an objective lens,
6 is a recording medium, 7 is a 1,72 wave plate, 8 is a lens, 9 is a polarizing beam splitter, and 10 is a two-split detection company. In this embodiment, one polarizing beam splitter and a lens 8 are used instead of the conventional cube-shaped polarizing beam splitter 21 and two lenses 22, and two lenses are used instead of the detector 23.
A divided detector 10 is used.

The light reflected by the recording medium 6 is focused by the objective lens 5, reflected by the half mirror 4, passes through the 1/2 wavelength plate 7, is focused by the lens 8, and is polarized by the polarizing beam splitter 9 (S) (
The light is separated into shoulder light and normal (P) light, each reflected and incident on the two-split detector 10. Recording medium 6
The reflected light of the linearly polarized laser beam irradiated with the polarization plane rotates due to the Kerr effect in the direction of magnetization, so the amount of light of the abnormally polarized light and the normally open light reflected by the polarizing beam splitter changes, resulting in two-split detection. The output of each side of the device 10 changes. Furthermore, by making this two-divided detector 10 into a differential configuration, it is possible to cancel the medium noise and read the information on the recording medium 6.

2 and 3 are cross-sectional views of two examples of the polarizing beam splitter 9 of FIG. 1. In the figure, 11 is a right angle prism, 12
1 is a polarizing film, 13 is a parallel plane plate, and 14 is a total reflection film. The polarizing film 12 is a deposited film that reflects abnormally polarized light and transmits normally open light, and the total reflection film 14 is a deposited film that reflects normally open light. With this configuration, by setting the parallel plane plate 13 to a predetermined thickness, abnormal light leakage and normally open light can be separated by giving a predetermined separation width. In this example, right angle prism 1
1, the output direction may be changed using a triangular prism having an arbitrary angle instead of a right angle, or the edge portion of the triangular prism on the side through which light does not pass may be shaved off. Further, by using a wedge plate instead of the parallel plane plate 13, the separation width between the extraordinary polarized light and the ordinary polarized light can be changed.

In another polarizing beam splitter 9 shown in FIG. 3, a lens 15 and a 1/'2 wavelength plate 16 are added to the polarizing beam splitter shown in FIG. are glued together in this order to make it smaller.

〔Effect of the invention〕

As explained above, the present invention uses a single polarizing beam splitter as an analyzer, which is composed of a triangular prism, a parallel plane plate or a wedge plate, a polarizing film, and a total reflection film, instead of a conventional cube-shaped polarizing beam splitter. By using a printer, it is possible to make the optical system smaller and reduce the number of parts, which has the effect of making the magneto-optical recording and reproducing device more compact.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magneto-optical recording/reproducing apparatus according to an embodiment of the present invention, FIGS. 2 and 3 are cross-sectional views of two examples of the polarizing beam splitter shown in FIG. 1, and FIG. FIG. 1 is a configuration diagram of a magnetic recording/reproducing device. In the figure, 1 is a laser light source, 2 is a collineau 1 to lens, 3 is a dimmer, and 4 is a half mirror 15.
is an objective lens, 6 is a recording medium, 7.16 is a half-wave plate, 8, 15.22 are lenses, 9 is a polarizing beam splitter, 10 is a two-split detector, 11 is a right-angle prism, 12 is 1
13 is a parallel plane plate, 14 is a total reflection model, 4th
figure

Claims (1)

[Claims] A linearly polarized light beam is irradiated onto a magneto-optical recording medium, and the linearly polarized light reflected from the recording medium is incident on an objective lens.
In a magneto-optical recording and reproducing device that reads information recorded on the recording medium by guiding the information to a detector via an analyzer, the analyzer includes a triangular prism and a parallel plane plate or a wedge plate joined to the slope of the triangular prism. a polarizing film provided on the joint surface of the triangular prism and the plate to reflect abnormally polarized light and transmit ordinary polarized light, and a total reflection film provided on the other surface of the plate to reflect ordinary polarized light. 1. A magneto-optical recording and reproducing device comprising a polarizing beam splitter.