JPH02304752A - Magneto-optical recording medium and magneto-optical information reproducing device - Google Patents

Abstract

PURPOSE:To reduce the degradation of signal quality when a medium and a device are used at a high temperature by changing a ratio N1/N2 for the length of a main axis in a substrate according to a specified condition with the rise of the temperature. CONSTITUTION:One main axis N3 of the main axes in the refraction factor elliptical body of a substrate 1 is almost vertical to the surface of the substrate and other two main axes N1 and N2 are almost parallel to the surface of the substrate. Then, the main axis closed to a polarizing surface 21 for the linear polarized light of incident light is defined as the N1 and the remained main axis is defined as the N2. At such a time, when the rotating direction of the polarizing surface 21 by a magneto-optical effect in a recording layer 3 is coincident with the rotating direction of elliptical polarized light for emissive light, the N1/N2 is increased with the rise of the temperature and the N1/N2 is decreased in an opposite case. Accordingly, the elliptical polarized light of the emissive light is decreased to be elliptical with the rise of the temperature. Thus, when the medium and device are used at the high temperature, the degradation of the signal quality can be reduce.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical recording medium and a magneto-optical information reproducing apparatus using the magneto-optical recording medium.

[Background Art] In recent years, with the development of information technology, optical information recording and reproducing devices have attracted attention as mass storage devices.

Among these optical information recording and reproducing devices, the magneto-optical recording method is attracting attention because it is rewritable.

In this magneto-optical recording, a magnetic thin film having perpendicular magnetic anisotropy is formed on a transparent substrate by sputtering etc. as a recording medium, and information is recorded by forming pits with different magnetization directions in the magnetic thin film. .

FIG. 9 shows an example of a cross section of a magneto-optical disk which is the recording medium. This magneto-optical disk has a dielectric thin film 21 for protection on a polycarbonate substrate 1, and a magnetic thin film 3 made of, for example, a rare earth transition metal alloy thin film. and a dielectric thin film 4 for protection are sequentially formed. A laser beam 5 for recording and reproducing is transmitted through the polycarbonate substrate 1 and focused on the magnetic thin film 3. Before forming recording pits in this magnetic thin film 3, after aligning the magnetization direction of the magnetic thin film 3 in one direction, a high power laser beam is applied as shown in FIG. 9 while applying an external magnetic field. Then, the light is focused on the magnetic thin film 3, and the magnetic thin film 3 is heated to a temperature close to one point. As the coercive force of the heated part decreases, the magnetization reverses in the direction of the external magnetic field.
As shown in FIG. 10, pits 6 are formed as magnetization reversal domains. Moving the recording medium - 1 In other words, while rotating the magneto-optical disk, the power of the laser beam is increased in pulses as soon as the pits 6 are formed, as shown in Figure 10, information is recorded. will be done.

When reading the information recorded by the recording pits 6, a magneto-optical effect called a magneto-optical effect is used as much as possible. However, as shown in FIG. 11, due to the magnetization direction of the magnetic thin film 3, the plane of polarization of the incident linearly polarized light is slightly rotated and reflected. Since the direction of rotation of the plane of polarization is reversed depending on the direction of magnetization, this plane of polarization can be extracted as an electrical signal using a known differential magneto-optical pickup. Incidentally, the differential magneto-optical pickup includes, for example, a magnetic a-film 3
The reflected light whose polarization plane has been rotated is separated into two mutually orthogonal polarization components by a polarizing beam splitter, and the light intensity of these two polarization components is photoelectrically converted by two photodetectors. The information signal is obtained by taking the differential of the detector.

[Problems to be Solved by the Invention] FIG. 12 is a diagram showing the rotation of the plane of polarization due to the Kerr effect, viewed along the traveling direction of light. As shown in this figure, with respect to the direction 16 of the incident linearly polarized light, the plane of polarization of the reflected light is rotated by θ to the right or left depending on the magnetization direction of the magnetic thin film 3. However, in the actual magnetic thin film 3, in addition to the rotation of the plane of polarization due to the Kerr effect, due to the Kerr ellipse effect,
As shown in FIG. 13, linearly polarized light becomes elliptical (polarized). The rotation direction of this elliptically polarized light is determined by the composition of the magnetic thin film 3 and the optical design including the dielectric thin film, etc., as shown in Fig. 13 (a).
), (b), there may be some that cause rotation in the opposite direction. What is shown in Figure 13(a) is that when the rotation of the plane of polarization due to Kerr rotation is clockwise, the rotation direction of elliptically polarized light is clockwise, and when the rotation of the plane of polarization due to Kerr rotation is counterclockwise, the rotation direction of elliptically polarized light is clockwise. This is the case where the rotation direction is counterclockwise, and the 13th
What is shown in Figure (b) is that when the rotation of the plane of polarization due to Kerr rotation is clockwise, the rotation direction of elliptically polarized light is counterclockwise, and when the rotation of the plane of polarization due to Kerr rotation is counterclockwise, the rotation direction of elliptically polarized light is clockwise. This is the case when it is around.

The difference between these two types can be understood as a difference in response to circularly polarized light. That is, linearly polarized light is represented by a combination of two circularly polarized lights that rotate in opposite directions. Then, as the phase of one of the two circularly polarized lights advances relative to the other, the plane of polarization rotates. Then, when the right-handed circularly polarized light and the left-handed circularly polarized light are reflected by the recording multilayer film,
When the reflectance of the circularly polarized light that is reflected with an advanced phase is higher than the reflectance of the other circularly polarized light, it will be as shown in Figure 13 (a), and conversely, when it is low, it will be as shown in (b). Become.

It is known that when the reflected light from such a recording medium is reproduced by a magneto-optical pickup as described above, the carrier level of the reproduced signal changes due to the phase difference of the pickup itself. Note that the phase difference of the pickup itself is caused by a reflection prism or the like in the optical system of the pickup.

FIG. 14 shows changes in the carrier level and the polarization state of the reflected light due to the phase difference of the optical system of the pickup when reflected light as shown in FIGS. 13(a) and 13(b) is obtained. If the ellipticalization of the reflected light from the medium is O or small, the change in carrier level with respect to the phase difference of the pickup optical system is approximately CO, where the phase difference is δ.
The curve is Sδ, but the reflected light (
Hereinafter, this will be referred to as type (a) reflected light. ), the carrier level characteristics are such that the peak shifts in the negative direction as shown in FIG. 14(a), and the reflected light (
Hereinafter, this will be referred to as type (b) reflected light. ), the peak of the carrier level characteristic shifts in the positive direction as shown in FIG. 14(b). In Fig. 14, the phase difference of the pickup optical system is the phase difference between the incident linearly polarized light direction and the direction perpendicular to it, and when the phase in the incident linearly polarized direction leads the phase in the direction perpendicular to this. is correct.

For the reflected wave of the type (a), as shown in Fig. 14(a)
As shown in , when the optical system of the pickup has a negative phase difference, the elliptically polarized light approaches linearly polarized light, the effective Kerr rotation angle increases, and the carrier level reaches its maximum accordingly. In this case, the direction shown by reference numeral 17 in Fig. 14 (a>) is the fast axis with respect to the direction 16 of the incident linearly polarized light.On the other hand, in the case of reflected light of type (b), the direction shown by reference numeral 17 in Fig. 14 (b)
As shown in , the carrier level is maximum when the optical system of the pickup has a positive phase difference. In this case, the first
The direction indicated by reference numeral 18 in FIG. 4(b) is the slow axis with respect to the direction 16 of the incident linearly polarized light.

In an actual pickup, the phase difference of the optical system is designed in the vicinity of O, so that only a carrier level lower than the maximum gear level can be obtained, as shown by the circle in FIG. In FIG. 14, reference numeral 20 indicates the range of variation in the phase difference of the pickup.

Furthermore, in general, as the temperature of a magneto-optical disk medium increases, its magneto-optic effect decreases and the Kerr rotation angle decreases, so at high temperatures the carrier level decreases and signal quality deteriorates. FIG. 15 shows a temperature change in the carrier level of a recording medium having characteristics as shown in FIG. 14(a). In this figure, T1. T2 and T3 are temperatures, and T
The relationship is l < T2 < T3.

In this way, in addition to a decrease in carrier level due to ellipse, the carrier level also decreases due to high temperature. Conventionally, recording media with large ellipse have a problem of deterioration of signal quality when used at high temperatures. Ta.

The present invention has been made in view of the above circumstances, and provides a magneto-optical recording medium that can reduce deterioration of signal quality when used at high temperatures, and a magneto-optical information reproducing device using this magneto-optical recording medium. It is intended to.

[Means for Solving the Problems] The magneto-optical recording medium of the present invention includes a substrate and a recording layer formed on the substrate, in which three main axes Nl and N2 of the index ellipsoid of the substrate.

One of the principal axes N3 out of N3 is substantially perpendicular to the substrate surface, and the principal axis near the polarization plane of the incident linearly polarized light is N1, and the remaining principal axes are N2, then the principal axes N1 . N
The length ratio Nl/N2 of 2 changes as follows with respect to temperature changes, at least in the inner circumference side region of the magneto-optical recording medium.

(A) When the direction of rotation of the plane of polarization due to the magneto-optic effect in the recording layer and the direction of rotation of the elliptically polarized light of the light emitted from the magneto-optical recording medium match, as the temperature rises, Nl/N2
increases.

(B) When the direction of rotation of the plane of polarization due to the magneto-optic effect in the recording layer is opposite to the direction of rotation of the elliptically polarized light of the light emitted from the magneto-optical recording medium, Nl/N2 decreases as the temperature rises.

The magneto-optical information reproducing device of the present invention is a magneto-optical recording medium having a substrate and a recording layer formed on the substrate, the magneto-optical recording medium having three main axes N1, . N2
, N3, one of the principal axes N3 is substantially perpendicular to the substrate surface, and the other principal axes are N1 . When N2, at least in the inner region of the magneto-optical recording medium,
(A) When the direction of rotation of the plane of polarization due to the magneto-optic effect in the recording layer and the direction of rotation of the elliptically polarized light of the light emitted from the magneto-optical recording medium match, the principal axis Nz,
The length ratio Nl/N2 of N2 increases, and (B) the rotation direction of the plane of polarization and light due to the magneto-optic effect in the recording layer!
! When the rotation direction of the elliptically polarized light emitted from the optical recording medium is opposite, linearly polarized light is irradiated onto the magneto-optical recording medium whose Nl/N2 decreases as the temperature rises to perform the magneto-optical recording. A device that receives return light from a medium and reproduces information recorded on the magneto-optical recording medium, wherein the plane of polarization of the linearly polarized light irradiated onto the magneto-optical recording medium is set to one of the principal axes Nl and N2. The direction is close to N1.

[Function] In the magneto-optical recording medium of the present invention, as the temperature rises, Nl
By changing /N2 under the above-mentioned conditions, the ellipticalization of the elliptically polarized light emitted from the magneto-optical recording medium is reduced.

Further, in the magneto-optical information reproducing apparatus of the present invention, the polarization plane of the linearly polarized light irradiated onto the magneto-optical recording medium exhibiting a predetermined change in N1/N2 is set to the main lNlN1 of the substrate of the magneto-optical recording medium.
By setting the direction close to N1 of N2, the change in N1/N2 acts to reduce the ellipticalization of the elliptically polarized light of the light emitted from the magneto-optical recording medium as the temperature rises.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

1 to 8 relate to one embodiment of the present invention, in which FIG. 1 is an explanatory diagram showing the relationship between the principal axis of the substrate and incident linearly polarized light, and FIG.
The figure is a cross-sectional view of a magneto-optical disk, Figure 3 is an explanatory diagram showing the configuration of a magneto-optical pickup, Figure 4 is an explanatory diagram showing the direction of the main axis of the substrate, and Figure 5 is the ratio of the length of the main axis of the substrate. A characteristic diagram showing the temperature characteristics of the carrier level. Figure 6 is a characteristic diagram showing the dependence of the carrier level on the phase difference of the pickup optical system at different temperatures when using a substrate with the characteristics shown in Figure 5. Figure 7 is a characteristic diagram showing the dependence of the carrier level on the phase difference of the pickup optical system at different temperatures. A characteristic diagram showing the ratio of the main axis length of the substrate and the temperature characteristic of the carrier level, which has different characteristics from FIG. 5,
FIG. 8 is a characteristic diagram showing the dependence of the carrier level on the phase difference of the pickup optical system at different temperatures when a substrate having the characteristics shown in FIG. 7 is used.

Before explaining the specific configuration of this embodiment, an overview of this embodiment will be explained.

It has become clear that the ellipticalization of reflected light from a magneto-optical recording medium is not determined only by the magnetic film or dielectric layer, but is also affected by the birefringence of the substrate.

For example, in a substrate using plastic, as shown in FIG. 1, one of the principal axes N3 of the index ellipsoid of the substrate 1 is approximately perpendicular to the substrate surface, and the other two principal axes N1
．． Although N2 is approximately parallel to the substrate surface, for example, as shown in FIG.
If one of the principal axes of in-plane birefringence, for example N1, substantially coincides with each other, the ellipticity of the reflected wave increases or decreases depending on the magnitude relationship between the principal axes N2 and N1. Figure 13 (a
), the type shown in Figure 14(a), that is, when the rotation of the plane of polarization due to Kerr rotation is clockwise, the rotation direction of the elliptically polarized light is clockwise, and when the rotation of the plane of polarization due to Kerr rotation is counterclockwise, it is elliptically polarized light. For a type of medium in which the direction of rotation is counterclockwise (type (a)), if N2 is smaller than N1,
As the ovalization becomes smaller, the effective Kerr rotation angle 19, which is the deflection angle of the principal axis of the elliptically polarized light, increases, and the carrier level increases. This shows that in the (a) type, the rotation direction of elliptically polarized light is such that the phase in the entrance polarization direction is ahead of the phase in the direction perpendicular to this, but N1 is higher than N1.
This is because when 2 is small, the incident linearly polarized direction coincides with the slow axis, resulting in a small phase difference. On the other hand, Fig. 13 (b
), the type shown in Figure 14(b), that is, when the rotation of the plane of polarization due to Kerr rotation is clockwise, the rotation direction of the elliptically polarized light is counterclockwise, and when the rotation of the plane of polarization due to Kerr rotation is counterclockwise, it is elliptically polarized light. In a type of medium in which the direction of rotation is clockwise (type (b)), on the contrary, when N2 is larger than N1, a similar effect is produced.

The birefringence of the substrate 1 changes depending on the temperature, but as mentioned above, in the (a>type), as the temperature rises, Nl
By selecting a substrate that increases /N2, it is possible to reduce the decrease in carrier level due to temperature rise. In addition, in type (b), as the temperature rises, Nl/
By selecting a substrate that reduces N2, it is possible to reduce the decrease in carrier level due to temperature rise.

Next, the magneto-optical disk of this embodiment will be explained.

The magneto-optical disk 100 has a dielectric thin film 22 for protection on a polycarbonate substrate 1, and a magnetic thin film 3 made of, for example, a TbFeCo alloy. and Aj! The alloy reflective films 22 are laminated in order.

A light beam for recording and reproducing is transmitted through a polycarbonate substrate 1 and focused on a magnetic thin film 3.

The magneto-optical pickup 200 for reproducing information recorded on the magneto-optical disk 100 is configured, for example, as shown in FIG. Linearly polarized light emitted from the semiconductor laser 10 is collimated by a collimator lens 9, transmitted through a beam splitter 8, and focused onto the magnetic thin film 3 of the magneto-optical disk 100 by an objective lens 7. It has become. In the figure, reference numeral 15 indicates the linear polarization direction of the incident light. The light reflected by the magnetic thin film 3 undergoes Kerr rotation according to the magnetization direction of the magnetic 1g 83, passes through the objective lens 7, is reflected by the beam splitter 8, and enters the 1/2 wavelength plate 11. This one
The /2 wavelength plate 11 has an azimuth angle set to 22.5° so as to rotate the plane of polarization by 45°. The light that has passed through the 1/2 wavelength plate 11 enters the polarizing beam splitter 12, where it is separated into two polarized components orthogonal to each other. These two polarized light components are transmitted through the condensing lens 138.
The light is focused at point b and received by photodiodes 14a and 14b. Then, an information signal is obtained by using a differential amplifier 30 to calculate the difference between the outputs of the photodiodes 14a and 14b.

Incidentally, in this embodiment, it is assumed that the characteristics of the reflected light on the magneto-optical disk 100 are as shown in type (a). On the other hand, the magneto-optical pickup 2
00 uses a laser beam having a polarization plane 21 parallel to the circumferential direction of the magneto-optical disk 100, as shown in FIG.

Therefore, in this example, as shown in FIG. 4, in-plane birefringence is such that the principal axis N3 is approximately perpendicular to the substrate surface, the principal axis N1 is oriented in the circumferential direction, and the principal axis N2 is oriented in the radial direction. 5, the length ratio Nt/N2 increases as the temperature rises, as shown in FIG. There is.

As a result, as described above, it is possible to realize the magneto-optical disk 100 in which the carrier level hardly decreases, as shown in FIG. 5, even in a high-temperature environment.

Here, the carrier level at 25°C and 50°C,
FIG. 6 shows the dependence of the pickup optical system on the phase difference. As shown in this figure, the carrier level is 23 at 25°C, while the carrier level is 24 at 50°C.
The level of N1/N1 decreases as the magneto-optic effect decreases and the Kerr rotation angle decreases, but as the temperature rises, N1/
As N2 increases, the peak shifts in the positive direction due to decreased ovalization. Therefore, if a magneto-optical pickup 200 with zero phase difference is used, the carrier level hardly changes even if the temperature rises, as shown by the circle in FIG. In addition, the curve shown by the dashed line in FIG. 6 shows the carrier level at 50° C. when Nl/N2 does not change, and it can be seen that in this case, the carrier level decreases.

Note that the actual magneto-optical pickup 200 has variations in phase difference, as shown by reference numeral 20 in FIG. be able to.

Furthermore, the characteristics of the reflected light on the magneto-optical disk 100 are as follows:
(b) type, the magneto-optical pickup 200 uses a laser beam with a polarization plane parallel to the circumferential direction of the magneto-optical disk 100, as shown in FIG. A substrate 1 is used in which /N2 decreases as the temperature increases, as shown in FIG. 7, at least in the inner peripheral region of the magneto-optical disk 100.

As a result, as in the type (a), it is possible to realize a magneto-optical disk 100 in which the carrier level hardly decreases even in a high temperature environment, as shown in FIG.

Figure 8 shows the temperature at 25°C when using a substrate with the characteristics shown in Figure 7.
and the dependence of the carrier level at 50° C. on the phase difference of the pickup optical system. As shown in this figure, for a carrier level of 23 at 25°C, 50
The carrier level 24 at .degree. C. decreases, but as the temperature increases, Nl/N2 decreases and ovalization decreases, so the peak shifts in the negative direction. Therefore, when a magneto-optical pickup 200 with a phase difference of O is used, the carrier level hardly changes even if the temperature rises, as shown by the circle in FIG. still,
The curve shown by the dashed line in FIG. 8 shows the carrier level at 50° C. when Nl/N2 does not change.

In this way, according to this embodiment, as the temperature rises, Nl/N2 of the substrate 1 changes under predetermined conditions, so that
Since the ellipticalization of the elliptically polarized light of the light emitted from the magneto-optical disk 100 is reduced, it is possible to reduce the decrease in the carrier level of the reproduced signal due to the magneto-optic effect of the magneto-optical disk 100 decreasing with the upper temperature limit. This reduces deterioration in signal quality when used at high temperatures.

It should be noted that the present invention is not limited to the above-mentioned embodiments. For example, the present invention is not limited to the above embodiments. For example, N
Films in which l/N2 changes under the conditions described above may be stacked.

[Effects of the Invention] As explained above, in the magneto-optical recording medium of the present invention, as the temperature rises, the ratio N1/N2 of the main axis length of the substrate changes under predetermined conditions. In addition, in the magneto-optical information reproducing apparatus of the present invention, the polarization plane of the linearly polarized light irradiated onto the magneto-optical recording medium exhibits a predetermined change in Nl/N2 of the substrate. of,
By setting the direction close to N1 of the main axes N1 and N2, the change in N1/N2 acts to reduce the ellipticalization of the elliptically polarized light of the light emitted from the magneto-optical recording medium as the temperature rises. . Therefore, both inventions have the effect of reducing deterioration in signal quality when used at high temperatures.

[Brief explanation of the drawing]

1 to 8 relate to one embodiment of the present invention, in which FIG. 1 is an explanatory diagram showing the relationship between the principal axis of the substrate and incident linearly polarized light, and FIG.
The figure is a cross-sectional view of a magneto-optical disk, Figure 3 is an explanatory diagram showing the configuration of a magneto-optical pickup, Figure 4 is an explanatory diagram showing the direction of the main axis of the substrate, and Figure 5 is the ratio of the length of the main axis of the substrate. A characteristic diagram showing the temperature characteristics of the carrier level. Figure 6 is a characteristic diagram showing the dependence of the carrier level on the phase difference of the pickup optical system at different temperatures when using a substrate with the characteristics shown in Figure 5. Figure 7 is a characteristic diagram showing the dependence of the carrier level on the phase difference of the pickup optical system at different temperatures. A characteristic diagram showing the ratio of the main axis length of the substrate and the temperature characteristic of the carrier level, which has different characteristics from FIG. 5,
Figure 8 is a characteristic diagram showing the dependence of the carrier level on the phase difference of the pickup optical system at different temperatures when a substrate with the characteristics shown in Figure 7 is used; Figure 9 is a cross-sectional view of a conventional magneto-optical disk; FIG. 10 is a perspective view showing a bit formed on a magnetic film, FIG. 11 is an explanatory diagram showing the relationship between the magnetization direction of the magnetic film and Kerr rotation, and FIG. 12 is an explanatory diagram showing the rotation of the plane of polarization due to the Kerr effect. Figure 13(a). (b) is an explanatory diagram showing the ellipticalization of linearly polarized light due to reflection on a magnetic film, and Figures 14 (a) and (b) are changes in the carrier level and polarization state of reflected light due to the phase difference of the optical system of the pickup. FIG. 15 is a characteristic diagram showing the temperature change of the carrier level of the recording medium. 1...Polycarbonate substrate 3...Magnetic thin film 10...Semiconductor laser 100...Magneto-optical disk 200...Engraving of magneto-optical pickup drawing (no change in content) Fig. 1 Fig. 2-! Fig. 3 Fig. 4 Fig. 5 Fig. 6 d) Inλ1 yota - Fig. 9 Fig. 10 ee8J eθ Fig. 12 Fig. 15 Fig. 13 Fig. 14 (G) (b) May 29, 1989 Day 2, Title of the invention: Magneto-optical recording medium and magneto-optical information reproducing device 3, Relationship with the case of the person making the amendment: Patent ratio 1

Claims (2)

[Claims] (1) In a magneto-optical recording medium having a substrate and a recording layer formed on the substrate, three main axes N_1, N_2, of the index ellipsoid of the substrate,
When one principal axis N_3 of N_3 is substantially perpendicular to the substrate surface, and the principal axis near the polarization plane of the incident linearly polarized light is N_1, and the remaining principal axes are N_2, the length of the principal axes N_1 and N_2 is A magneto-optical recording medium characterized in that the ratio N_1/N_2 changes as follows with respect to temperature changes, at least in an inner peripheral region of the magneto-optical recording medium. (A) When the direction of rotation of the plane of polarization due to the magneto-optic effect in the recording layer and the direction of rotation of the elliptically polarized light of the light emitted from the magneto-optical recording medium match, as the temperature rises, N_1/N_
2 increases. (B) If the direction of rotation of the plane of polarization due to the magneto-optic effect in the recording layer is opposite to the direction of rotation of the elliptically polarized light of the light emitted from the magneto-optical recording medium, N_1/N_2
decreases. (2) having a substrate and a recording layer formed on this substrate;
three principal axes N_1, N_2, of the index ellipsoid of the substrate;
When one of the main axes N_3 is substantially perpendicular to the substrate surface, and the other main axes are N_1 and N_2, at least in the inner circumferential region of the magneto-optical recording medium, (A) the above-mentioned When the direction of rotation of the plane of polarization due to the magneto-optic effect in the recording layer and the direction of rotation of the elliptically polarized light of the light emitted from the magneto-optical recording medium match, the principal axis N_1,
When the length ratio N_1/N_2 of N_2 increases, and (B) the direction of rotation of the plane of polarization due to the magneto-optic effect in the recording layer is opposite to the direction of rotation of the elliptically polarized light of the light emitted from the magneto-optical recording medium, As the temperature rises, the above N_1/N
Magneto-optical information reproduction in which information recorded on the magneto-optical recording medium is reproduced by irradiating linearly polarized light onto a magneto-optical recording medium in which __2 decreases and receiving return light from the magneto-optical recording medium. 1. A magneto-optical information reproducing device, characterized in that the plane of polarization of the linearly polarized light irradiated onto the magneto-optical recording medium is in a direction close to N_1 of the principal axes N_1 and N_2.