JPS6066338A - Method and apparatus for recording or reproducing information - Google Patents

Abstract

PURPOSE:To speed up positional adjustment of focused light on a recording medium and attain precise focus adjustment by focusing polarized light on the surface of the recording medium by using the 0-order diffracted light at the diffraction. CONSTITUTION:The 0-order diffracted light 29 and a polarized light 30 projected from a polarizer using an elastic surface wave form an image on the recording medium 27 through a beam splitter 22 and an objective lens 24. The reflected light based upon the polarized light 30 is used for the recording and reproducing of information and the reflected light due to the 0-order diffracted light 29 is guided to a two-divided phtodetector 26 and used for the control of a focus 31. Since the surface of the photodetector 26 has a conjugate relation to the surface of the recording medium 27, focus adjusting signal light is not oscillated on the surface of the detector 26 even if the polarized light is polarized in any direction, so that always precise focus control is attained and the positional adjustment of the fucused light can be speeded up.

Description

[Detailed description of the invention] The present invention relates to an information recording or reproducing method and apparatus.

In recent years, with the development of the information society, information recording or 413 recording devices such as optical disk devices and magneto-optical disk devices that record or reproduce information by focusing light on the surface of a recording medium have been attracting attention. In this type of 1-hour information recording or reproducing apparatus, focus adjustment and position adjustment of the focused light on the surface of the recording medium are lacking. Conventionally, mechanical deflection means such as a galvano mirror has been used for the position adjustment, but this has the drawback of slow scanning speed. Therefore, in place of the mechanical deflection means,
It is conceivable to use an optical deflector that utilizes diffraction, as proposed in No. 7217. An information recording or reproducing device using such an optical deflector uses a high-speed position f ('fJ4
Although it has an excellent property of being able to adjust the focus, a problem arose in signal detection for focus adjustment.

This example will be explained using FIG. 1(E) [F]).

In FIG. 1(c), l is an optical deflector that utilizes light diffraction by elastic surface waves, 2 is a beam splitter, 3 is an objective lens drive means, 4 is an objective lens, 5 is a condenser lens, 6
7 is a detector, and 7 is a recording medium.

Here, the optical deflector 1 is configured as shown in FIG. 1, for example. A sub-wavelength layer 12 having a higher refractive index than the substrate 11 is formed on the substrate 11, and incident light 15 is transmitted into the sub-wavelength layer 12 via a prism coupler 14. and 4
A portion of the incident light passing through the wave path is reflected by the surface acoustic wave 18 generated by the comb tooth-shaped electrode 13 and becomes polarized light 16. By this polarized light 16 and surface acoustic wave 18,
The zero-order beam 17 that is not deflected is ejected out of the waveguide through the prism coupler 19.

In FIG. 1, the deflected light 8 emitted from the optical deflector l is transmitted through the beam splinter 2, and is transmitted through the objective lens 3.
It is focused on the recording medium 7. The polarized light reflected by the recording medium is guided toward the photodetector 6 by the beam splitter 2, and is imaged on the photodetector 6 by the condenser lens 5. The objective lens driving device 3 is driven in accordance with the signal detected by the photodetector 6, and the objective lens 4 is moved so that the focus of the deflected light coincides with the surface of the recording medium.

However, in the above-mentioned information recording or recording apparatus, the recording medium 7 surface and the photodetector 6
Since the surfaces are in a conjugate relationship, the focus adjustment signal light 9 is scanned by the optical deflector IK, and the optical detector 6 is scanned by the optical deflector IK.
Full movement on the surface, precise movement (the disadvantage is that it is difficult to control one point).

The object of the invention is to focus light on a recording medium (1) and to provide information recording in which the position of the light on the recording medium (7) can be adjusted at high speed and the focus can be adjusted accurately when recording or reproducing information. Alternatively, it is possible to provide a regeneration method and an O-device.

In the present invention, light deflected by diffraction is recorded.

In an information recording or reproducing method and apparatus for recording or reproducing information by focusing on a body surface, the above object is achieved by controlling the focus of the polarized light on the recording medium surface using the 0th order diffracted light in the diffraction. It is something.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic diagram showing a first embodiment of the information recording or reproducing apparatus of the present invention. In the figure,
22 is a beam splitter, 23 is an objective lens driving device, 24 is an objective lens, 25 is a condensing lens, 26 is a two-split photodetector, 27 is a recording medium, and 28 is a light shielding plate. In the case of such an optical deflector using surface acoustic waves, the recording light and reproduction light are +1st order diffracted light or -1st order diffracted light.
First-order diffracted light is used, but since the diffraction efficiency of surface acoustic waves is usually less than 100 degrees, zero-order diffracted light is generated. In the present invention, the O-th new party is used privately to adjust the focus. That is, as shown in FIG. 2, the 0th-order diffraction source 29 and the deflected light 30U emitted from the optical deflector 11
, pass through the beam splitter 22, and are both imaged onto the recording medium 27 by the objective lens 24.

The polarized light 30 is modulated according to the recording signal and records information on the recording medium. Or, it enters the recording medium without modulation,
A detector (not shown) receives reflected light from the recording medium to reproduce information recorded on the recording medium. See you next time 290
The reflected light is guided by the beam splinter 22 to the two-split photodetector 26.

In the case of the first embodiment, as in the conventional example, the deflection angle is 30
There is a conjugate relationship between the original inspection surface and the recording medium surface, but since the 0th order new element is used for focus detection, no matter how the deflected light is deflected, it will not be reflected on the detector surface. signal light for focus adjustment (light reflected by the recording medium of 0th order diffraction block C)
never sways. In this way, the No. 1 objective lens driving device obtained by the two-split photodetector is accelerated so that the focal point 13 of the 0th-order lens 11 coincides with the surface of the recording medium 70.

In the above method, as shown in FIG. 2, if the focal point 31 of the 0th-order objective lens 24 coincides with the recording medium surface, the focal point 32 of the deflected light 30 with the condensing lens 24 also coincides with the recording medium surface. The entire premise is that
If the image plane position of the deflected light 30 is different from that of the zero-order diffracted light 29, such positional displacement is corrected and the objective lens In! II! I cultivated.

23 should be driven.

Next, the matching fish signal detection method of the above embodiment is shown in Fig. 3 (4) @
This will be explained using 0. This goldfish signal detection method is
For example, this method has been proposed in JP-A-54-155832, and the present invention is not limited to this method. Figure 3 (4) ■ (0 represents the state of reflected light from the recording medium surface of the 0th new party due to the difference in position between the objective lens 24 and the recording medium surface, and 33 represents the state of reflected light from the 0th time new party's surface. 34 is the medium surface when the recording medium is in front of the focusing male of the objective lens 24, 34 is the medium surface when the recording medium is at the focal position of the O-th order diffracted light, and 35 is the focus of the 0-th order new party. This shows the medium surface when there is a recording medium behind the position.As shown in Figure 3 (A), when the recording medium surface is also in front of the focal position of the zero-order objective lens. , the reflected light 38 from the medium passes through the objective lens 24 and becomes a diverging light flux, which enters the beam splitter 22.The beam splitter 22 bends the divergent light flux to the detector side, and half of the divergent light flux passes through the light shielding plate. As a result, the remaining light beam 39 is focused by the condensing lens 25.
The two halves are placed on one side 37 of the detector.

On the other hand, as shown in FIG. The light beam P enters the beam splitter 22.

The beam splitter 22Vc bends the parallel light flux toward the detector, and half of the parallel light flux is deflected by the light shielding plate 10 to 1l-1.As a result, the remaining light flux 41(1, condenser lens 25, an image is formed in the middle of the two-split photodetectors 36 and 37.

On the other hand, as shown in FIG. 3C), when the recording medium surface is located behind the 0th-order focal point position determined by the objective lens 24, the reflected light 42 from the medium is reflected by the objective lens 24.
Therefore, the convergent light beam becomes p, and the half of the two-split photodetector f! Enter lI 36.

Therefore, if the objective lens drive unit FIT 23 is driven so that the difference between the signals obtained from both 36 and 37 of the two-split photodetector is always zero, the 0th-order diffraction -)C condenser lens 24 The focus coincides with the recording surface.

Next, a second embodiment of the information recording or reproducing apparatus of the present invention will be described using FIG. 4. 51 is an optical deflector using elastic cinnabar waves, 63 is a one-wavelength plate, 64 and 65 are polarizing beam splitters, 52 is a beam splinter, 66 is a photodetector, 53 is an objective lens drive device, and 54 is an objective lens,
55 is a condenser lens, 56 is a two-split source detector, and 60 is a light shielding plate.

As explained in the section 51 of the optical deflector 51 (in Figure 1), since the planar optical waveguide is made of AIY structure, the polarized state of the light emitted from the optical deflector is box polarization. When the mode of the guided light is 'zTE mode, the oscillation direction of the electric field of both the zero-order element 61 and the deflected light 62 emitted from the deflector is within the plane of FIG. 4. On the other hand, the zero-order directed light 61 is converted into linearly polarized light orthogonal to the polarized light by the two-wavelength plate 63, and enters the polarized beam splitter 64 as it is.

The polarized light 62 incident on the polarizing beam splitter 64 is totally reflected by a surface 67 inside the polarizing beam splitter and becomes a 0th-order diffraction beam.
e61 and polarized light 621'2: combined. 0th order light 6
1 and the polarized light 62, the beam splitter 22
The light is transmitted through the condenser lens 54 and condensed onto the recording medium 57 . In the second embodiment, the O-th new beam can be focused very close to the position where the deflected light is focused, and the focus of the deflected light can be aligned on the recording medium with high precision. The combined light 6B is reflected from the recording medium 57 and is incident on the p-polarized beam splitter 65 by the beam splinter 22. Reproducing light 69, which is reflected light of the polarized light by the polarizing beam splitter 65, is detected by a photodetector 66Vc, and the information recorded on the recording medium 57 is reproduced. Also O
Next time, the reflected light of the new party passes through the polarizing beam splitter 65, and a part of it is blocked by the light shielding plate 10 and enters the t7.2 split photodetector 56, as in the first embodiment, and becomes a focus detection signal.

In the above example, the information recorded on the recording medium is optically read out and reproduced. However, by using the same constituent sounds and changing the polarized light according to the total information signal and projecting it onto the recording medium, It can also be an information recording device.

Next, a third embodiment of the inventive information recording or reproducing apparatus will be described with reference to FIG. 72 is a prism coupler, 74 is a surface acoustic wave, 77 Trr is an optical waveguide, and 78 is a thin film 11 made of a material having an electrical engineering effect.
A variable focal length thin film lens 80 is formed of an M lens and a constant volume that applies an electric field to the thin film lens, and the focal length is changed using the electro-optic effect by adjusting the voltage applied to the electrode. A recording tape 81 is a pad for pressing the recording tape against the waveguide end surface 84, 82.
83 is a two-part temperature detector, 86 is a C plate, 87 is a
This is a comb tooth-shaped electrode for generating ζ surface acoustic waves. The collicated laser beam 71 is guided into a waveguide 78 by a prism coupler 72. The guided light 73 is separated into a first-order diffracted light 75 and a zero-order diffracted light 7611 by the surface acoustic wave 74 generated from the comb tooth-shaped electrode 87. ”-The first-order diffracted light 75 and the O-th order pointing light 76 are both incident on the variable focus thin film l/lens 78, and the first-order diffracted light 75 is focused on the waveguide end face 84 like the recording waveguide light 79, Recording tape 81
Record above. On the other hand, the 0th order diffracted light 76 enters a variable focus thin film lens 78 . If the focal point of the variable focus film lens 78 is inside the waveguide end face 84, the guided light 85 will be incident on the 83 side of the two-split photodetector, while the variable focus type MIi% lens 781/m
When the focal point of the waveguide is outside the waveguide end face 84, 2!
1. The wave light 85 enters the 82 side of the 2-split photodetector, so a variable focus # film is used so that the difference between the signals obtained from both 82 and 83 of the 2-split photodetector is always zero. When a voltage is applied to the electrodes of the lenses, the recording waveguide light 79 travels to the waveguide end face 154.

The third embodiment has the effect of achieving ultra-miniaturization by providing a variable focus thin film lens having no mechanically moving parts and an optical deflector on the same row and wavefront. Also,
Also in this embodiment, an information reproducing apparatus can be constructed by providing means for detecting light from the optical 1L recording tape 80.

FIG. 6 shows a fourth embodiment of the information recording or reproducing apparatus of the present invention. In FIG. 6, 91 is a bus C using surface acoustic waves.
Deflector, 93 is an objective lens driving device, 94 is an objective lens, 95 is a condenser lens, 96 is a two-split photodetector, 97 is a recording medium, 100 is a light shielding plate, 103 is a single wavelength plate, 104 is a polarizing beam splitter 105 is a photodetector. Further, 108 and 109 are half mirror surfaces. Book 4
In this embodiment, the t-beam splitter 104 polarizes the 0th-order diffracted light 101 and the polarized light 102 based on the same principle as the second embodiment.
It is synthesized in ii 06. This combined light 107 is focused onto a recording medium 97 by a focusing lens 94 . The reflected light of the above-mentioned combined light is polarized beam splitter +7.The 9.0-order light component is transmitted through the vine 104 at the surface 106, while the polarized light component is reflected at the surface 106. The above zero-order light component is
It passes through the no-f mirror surface 108 and becomes a focus detection signal to the two-split source detector, while the deflected light component is
The light passes through the nof mirror surface 109, enters the photodetector 105, and becomes a reproduced signal.

The above example shows the case where the <-r\ information recorded on the recording medium is to be read out and reproduced, but using the same configuration, the polarized light is modulated according to the information signal and the information is recorded on the recording medium. By irradiating it, it can also be used as a p1 information recording device.

Like the second embodiment, the fourth embodiment has the advantage that it is possible to perform highly accurate focus adjustment, and the optical system is simpler than that of the second embodiment.

Next, a fifth embodiment of the information recording or reproducing apparatus of the present invention will be described using FIG. 7. While the first embodiment described above uses an acousto-optic effect in the optical deflector,
In the fifth embodiment, an electro-optic effect is used in the optical deflector. Reference numeral 111 denotes an optical waveguide formed in the same manner as in the example of FIG. is deflected by diffraction. The subsequent operation is exactly the same as in the first embodiment, and the 0th-order diffracted light 121 and the polarized ftJ122 are transmitted through the beam splitter 112 and directed onto the surface of the recording medium 117 by the objective lens 114, and information is recorded or reproduced by the polarized light. will be carried out. 0 again
A portion of the reflected light from the recording medium 117 of the next new party 121 is blocked by the light shielding plate 110, passed through the condensing lens 115, and detected by the two-split source detector IJ, 6.
A focus detection signal can be obtained using the same principle as explained in the figure. In accordance with this focus detection signal, the objective lens driving device 113 is fully driven to properly focus the deflected light 122 on the recording medium 117 surface. Based on the pitch A and the wavelength λ of the incident light, the following formula 1% (2) The pitch of the grating created this time is 8.81 mm,
7+, logarithm 1'! , 350 pairs, and the crossing width was 3 spaces.

Furthermore, in order to multiply the deflection angles, the VC may be formed by forming comb tooth-shaped electrodes with different pitches at different Bragg angles and inclinations, as shown in FIG. At h in Figure 8, 126
．． 127 and 128 are comb tooth-shaped electrodes with different pitches, 129 is the polarized light by the electrode 126, and 130 is the 12
1 of 7! Polarized light by the pole, 131 is polarized light by the electrode 128.

In the fifth embodiment, the grating tfW is formed on the optical waveguide using the electro-optic effect, and the original deflection is performed by diffraction, but the thermal beam effect can also be used. In this case, the electrodes formed on the optical waveguide similar to those in the fifth embodiment may have a ladder-shaped structure as shown in FIG. 9, and a heater material may be used as the electrode material. The relationship between the deflection angle and the pitch of the electron (1\\) is the same as when using the electro-optic effect.

The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, any optical deflector may be used as long as it deflects light using diffraction. Furthermore, the scope of application of the present invention is not limited to original disks and magneto-optical disks, but also image forming devices such as laser beam printers, display devices, etc., where image information is recorded on paper, clothing, etc. by scanning with a focused beam. It can also be applied to things.

As explained above, the present invention is an information recording or reproducing device that includes an original polarized metal that makes full use of diffraction, in which focus control is performed using the 0th-order diffraction original.
Even if the origin is deflected, it is now possible to always perform positive focus control.

[Brief explanation of the drawing]

Fig. 1 (5) [F]) is a schematic diagram showing an example of a conventional information recording or reproducing device and an optical deflector using the acoustic optical effect used therein, and Fig. 2 is an uninvented information recording or reproducing device. Schematic diagram showing the first embodiment of the device, Figure 3 (C)
40 to 7 are diagrams each showing other embodiments of the first layer recording or reproducing device of the present invention, and FIG. 8 is a diagram explaining the principle of focus detection in the first embodiment, respectively. FIG. 9 is a schematic diagram showing an example in which the deflection angles are multiplied in an optical deflector using a thermo-optic effect. FIG. 21... Optical deflector, 22... Beam splitter, 23... Objective lens drive device, 24... Objective lens, 25... Higashigen lens, 26... 2 division Original detector, 27... Q115 bodies, 28...
...Occupation source plate, 29...0th order diffraction source,
30...Polarized light, 31...Focus of 0th order diffraction source, 32...Focus of polarized light. Applicant: Canon Co., Ltd. fi mini-+ Agent: Gi Marushima -1i・1・・・、1に−・Bon・
, -~/35 -J36 R

Claims (2)

[Claims] (1) In an information recording or reproducing method in which light deflected by diffraction is focused on the surface of a recording medium to record or reproduce information, the source of the 0th-order diffraction in the diffraction is used to focus the polarized light on the surface of the recording medium. An information recording or reproducing method characterized by performing focus control. (2) an optical deflector using a light diffraction metal; a converging means for converging the polarized light from the optical deflector and the zero-order new beam onto the recording medium surface; comprising a detection means for detecting and obtaining a focus detection signal, and an adjustment means for adjusting the relative position between the focus position of the light focusing means and the recording medium surface according to the focus detection signal; An information recording or reproducing device that records or reproduces information.