JPH03120625A - Information recording and reproducing device - Google Patents

Abstract

PURPOSE:To improve a recording speed, to make the device into mass storage and to easily address to an arbitrary position by detecting and compensating defocusing when reference light and recording light, both of which are obtained by means of separating light flux from a laser, are converged in a recording means. CONSTITUTION:When reflected scattered light 119a is made incident on a four division photodetector 124b and a focusing position is shifted, it becomes oblong and the output of the detector 124b does not become mean. Thus, a difference with a focusing state is detected. The detected difference is amplification- processed in a focus detection device 127 (125), and a control signal is generated from a focus control lens driving control signal generation device 128a (126). Thus, a focus control lens driving device 128b (106) is controlled and focusing is attained on a recording medium 114 by moving a condenser lens 129 (mirror 105). Consequently, the diameter of a recording part 116 can be reduced, and laser light can accurately be held in a track part. Thus, recording can be speed ed up and addressing to the arbitrary position is facilitated, whereby the device can be made into mass storage.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an information recording/reproducing device, and in particular to an information recording/reproducing device that reversibly optically records an ultra-large amount of information using a recording medium containing polymeric liquid crystal, and easily records an extremely large amount of information. The present invention relates to an information recording and reproducing device that can reproduce information.

(Prior Art) Optical storage systems are currently in practical use as they have a large capacity and are excellent in random access. There are many different ways to do this, and for playback only, digital audio discs (C
D) and laser video discs (LD) have been put into practical use. Write-once optical discs (
WO), optical cards (OC) are known, and some use phase change of a metal thin film and others use bit formation of an organic dye.

Furthermore, research on rewritable optical discs is progressing.
Efforts are being made to put into practical use those that use the magneto-optical effect and those that use phase change. Among them, polymer liquid crystals have also been proposed as information recording media (Japanese Patent Laid-Open Nos. 59-10930, 59-35989, 62-154).
Publication No. 340). Among them, a recording method has been proposed in which the light reflectance is multivalued by changing the helical pitch length of cholesteric polymer liquid crystal or by forming non-oriented bits (Japanese Patent Laid-Open No. 62-10
7448, Kaimei 62-12937). In addition to information recording media, display devices using polymer liquid crystals have also been proposed (Japanese Unexamined Patent Publication No. 62-278529,
Publication No. 62-278530).

These proposed devices are capable of recording a relatively large amount of information and have excellent characteristics. However, in view of the current situation where the recording wavelength of magnetic recording can be down to about 0.1 μm, it cannot necessarily be said that the capacity is sufficiently large.

Holographic memory has been proposed as a device capable of ultra-large capacity recording using optical recording (P, J, va
n Horden, Appl, Gptics 2
．． 393 (1963)).

This method was difficult to put into practical use because at that time there were no reversible photosensitive materials for recording holograms.

However, recently, a reversible photosensitive material suitable for such purposes using a photoisomerization reaction of polymer liquid crystals has been proposed (Japanese Patent Laid-Open Nos. 87626-1987 and 191826-1982). ).

(Problems to be Solved by the Invention) In conventional information recording and reproducing devices, the diameter of pits recorded by holograms is large, making it difficult to increase capacity, and the recording speed is slow due to insufficient laser output. .

Furthermore, it is difficult to address an arbitrary position on the recording medium, and the area of the non-recording portion becomes large, making it difficult to increase the capacity.

The object of the present invention is to provide a precision information recording device that can increase the recording speed, increase the capacity, and easily address any position by appropriately setting the recording method and recording material.

(Means for Solving the Problems) The information recording and reproducing apparatus of the present invention separates the light beam from a laser into two light beams, a reference beam and a recording beam, by a light beam l! + stage, information imparting means for imparting information consisting of intensity modulation to the recording light;
A recording means and stage made of a polymeric liquid crystal recording material that interferes with the reference light and the recording light and records the interference, and detects diffracted light containing the information generated when the recording means is irradiated with the reference light. In an information recording and reproducing apparatus having a reproducing means having a photodetector, a focus detecting means detecting a shift in focus when the reference light and the recording light are focused on the recording means, and an output from the focus detecting means. The present invention is characterized in that it is provided with a focus correction means for correcting a focus shift based on a signal.

In addition, the present invention provides a displacement detection means for detecting a positional displacement between a focal point when the reference beam and the recording beam are condensed onto a recording medium of the recording means and a track provided on the recording medium. ,
The present invention is characterized in that it includes a displacement correction means for correcting the positional displacement based on an output signal from the displacement detection means.

(Example) FIG. 1(A) is a schematic diagram of a main part of an embodiment of the present invention.

In the figure, 101 is a laser driving device, and the laser 1
The output intensity and pulse width of 02 are controlled to perform optical modulation for recording or reproduction. As the laser 102, for example, a semiconductor laser is most suitable because it can easily perform such optical modulation, has a long coherence length, and has a single transverse mode.

A collimator lens 103 converts the light beam from the laser 102 into a parallel light beam. Reference numeral 104 denotes a beam separating means, which consists of a half mirror, etc., and includes a collimator lens 1.
The parallel light beam from 03 is separated into a transmitted recording beam 119 and a reflected reference beam 120.

At this time, the recording light 119 is subjected to intensity modulation by the shutter array 112 based on human input information. That is, a drive signal for driving the shutter array 112 is generated from the shutter array drive circuit 111 in response to a manual data signal generated by the input data transfer device 110 for information recording, and the recording light 119 is emitted according to the density change of the shutter array 112 at this time. Based on human resources information.

As the shutter array 112, for example, ferroelectric crystals, ferroelectric ceramics such as PLZT, liquid crystals, ferroelectric liquid crystals, etc. can be used. In particular, shutter arrays using surface-stabilized ferroelectric liquid crystals have the advantage of being able to be driven at high speed and outputting extremely large amounts of data (information) using their memory properties.

The recording light 119 that has been intensity (density) modulated by the shutter array 112 passes through the half mirror 121b, is reflected by the mirror 113, and is focused by the condenser lens 129 on a recording medium made of a polymeric liquid crystal composition that constitutes the recording means 116.
The light is focused on a photoreceptor (114). Note that 115 is a transparent substrate.

On the other hand, the reference beam 120 reflected by the beam separating means 104 passes through the half mirror 121a and the λ/4 plate 122, is reflected by the movable mirror 105, and is incident on the recording medium 114 of the recording means 116 by the condensing lens 108 as the recording beam 119. The light is focused at the same position.

The focused recording light 119 and reference light 120 interfere with each other, and holographically record interference fringes as a change in refractive index on the oriented polymer liquid crystal composition of the recording medium 114.

In this way, information based on the input data from the input data transfer device 110 is recorded on the recording medium 104 of the recording means 116.

In this embodiment, the polymeric liquid crystal composition serving as the recording medium (photoreceptor) 114 of the recording means 116 is composed of a polymeric liquid crystal and a light absorbing agent, as will be described later, and is coated on the surface of the transparent substrate 115 and then aligned. It is obtained through processing.

In this embodiment, a movable mirror 105 is driven by a multiplex recording mirror XYθ drive control device 106 to drive a mirror XYθ drive device 107, and by changing the position, inclination angle, etc., the reference beam 120 is directed to the recording means 116 at various angles.
It is input to.

By changing the data content of the recording beam 119 at each angle of incidence of the reference beam 120 in this way, multiplexed recording is possible by manually recording holographic data at each angle in the same recording bit, resulting in ultra-high capacity information. It makes recording easy.

Next, in this embodiment, the information recorded in the recording means 116 is reproduced as follows.

That is, as shown in the figure, only the reference beam 120 is irradiated onto the recording means 116 from the same direction as in the case of recording, and at this time, based on the interference fringes (hologram) recorded on the recording medium (photoreceptor) 114, The diffracted light beam is read by a photodetector (photodetector array) 117 and a reproduced signal is obtained by a photodetector signal processing device 118.

In this embodiment, the photodetector 117 and the photodetector signal processing device 118 constitute a reproducing means.

Note that the photodetector 117 is a Cds line sensor, a
-5i line sensor, CCD (chargecou
pled device), M OS (meta
l oxide semic.

nductor), Sachicon, Vidicon, CPD (
Charde priming device) etc. can be used.

Further, these photodetectors are selected depending on the wavelength of the reproduced light. By varying the incident angle of the reference beam 120, each piece of information multiplexed on the recording medium 114 is reproduced.

In this embodiment, the input information (data) provided by the shutter array 112 is directly detected by the photodetector 117 to obtain a reproduced signal, so that high-speed input information can be read.

In this embodiment, linearly polarized light may be used as the reproduction light, and in this case, it is desirable to adjust the polarization direction so that the reproduction S/N ratio is maximized.

In this embodiment, the content recorded on the recording medium 114 is erased by, for example, heating the entire recording medium and reorienting the recorded information portion.

It is also possible to partially reorient the recording portion by irradiating the recording portion with a laser beam of lower power for a longer time than during recording. In this embodiment, reorientation may be promoted by an electric field, a magnetic field, or the like during erasing.

FIG. 2 is a schematic cross-sectional view of one embodiment of the recording medium 114 used in the present invention.

In this embodiment, an ITO transparent electrode 202a is placed on a disk-shaped glass substrate 201a with a diameter of 130 mm and a thickness of 1.2 mm.
IR absorption dye (soluble naphthalocyanine, manufactured by Yamamoto Gosei Co., Ltd., IRD) is added to the following polymer compound (1).
After adding 0.5 wt % of 1001), the solution dissolved in cyflohexane was coated using a spinner, and after drying, a recording layer 205 containing polymer liquid crystal having a thickness of 5 μm was formed.

+C)l-C112τ C-0(I) a +CH2-)T o()coo()cN Next, UV hardening type exfoliant was applied to the disk-shaped glass substrate 201b on which the same ITO transparent electrode was formed. The 14th layer was applied by applying quinacrylate resin (manufactured by Mitsubishi Kasei, MP-121) and forming a spiral structure using a transfer method using a stamper.
A substrate with a groove shape in cross section as shown in the figure was created. The groove shape in this example has a lateral depth a = 0.08 μm.
, 41 width b = 20 μm, '(4 land width c = 5 μm
It is m.

Next, Au was deposited to a thickness of 100 nm using an electron beam to obtain a substrate having tracks.

A recording medium according to the present invention was formed by heat-pressing the substrate provided with the recording layer containing polymer liquid crystal and the substrate having tracks at 1200C.

Further, while applying a voltage of 100 V to the ITO electrodes provided above and below, the sample was cooled from 120° to room temperature to obtain an oriented sample.

Recording was performed on this recording medium using the storage recording/reproducing apparatus shown in FIG. 1(A) with an 830 nm, 40 mW semiconductor laser while rotating the recording medium. At this time, there was almost no shift in focus, and the size of the recording area was constant and stable at a diameter of 5 μm. Also, the track could be addressed without coming off.

When the information was reproduced using a reference light of 1 mW and the storage medium was rotated at 300 rpm, the information could be reproduced with an S/N of 35 dB. Also, during playback, the focus and tracking were stable and a good signal was obtained.

As the polymer liquid crystal compound used as the recording medium of the recording means according to the present invention, nematic polymer liquid crystal, chiral nematic polymer liquid crystal, smectic polymer liquid crystal, chiral smectic polymer liquid crystal, etc. are used, and main chain type polymer Either liquid crystal or side chain polymer liquid crystal may be used.

In addition, when using a polymeric liquid crystal having a nematic phase or a chiral nematic phase, it is desirable that the glass transition temperature is higher than room temperature.

The aforementioned polymeric liquid crystal compound can be used in combination with a low molecular weight liquid crystal in order to adjust its phase transition temperature and the like.

As the low molecular liquid crystal, nematic liquid crystal, smectic liquid crystal, chiral nematic liquid crystal, chiral smectic liquid crystal, and discotic liquid crystal are used.

Further, when writing and erasing are performed using a laser beam, it is preferable to add a laser-absorbing compound to the recording layer of a storage medium containing a polymeric liquid crystal because sensitivity is improved. Compounds used at this time include azo compounds, tetrabenzoporphyrin compounds,
Naphthoquinone compounds, aminium salt compounds, anthraquinone compounds, diimonium salt compounds, phthalocyanine compounds, metal chelate compounds, naphthalocyanine compounds, cyanine compounds, dioxazine compounds, merocyanine compounds, triphuedithiazine compounds compounds, xanthine-based compounds, crouniram-based compounds, triphenylmethane-based compounds, azulene-based compounds, lylium-based compounds, triphenylamine-based compounds, etc.

Polymer liquid crystals can be used in combination with several different types of polymer liquid crystals. It is also possible to use a mixture of a polymer liquid crystal and a low molecular liquid crystal, in which case the weight ratio is preferably 5 or less to 1 polymer liquid crystal.

Polymer liquid crystals may contain ordinary polymers (e.g. olefin resins, acrylic resins, polystyrene resins, polyester resins, polyurethane resins, polycarbonate resins), oligomers, various plasticizers, various stabilizers, quenchers, etc., as necessary. etc. may be contained.

For making the polymeric liquid crystal composition into a thin film, for example, the liquid crystal material may be sandwiched between a pair of disk substrates made of glass or plastic and then heated and pressure molded, or the liquid crystal material may be heated to an appropriate viscosity. There are methods of applying the material onto the disk substrate by spin code, dipping, bar code, roll coating, etc., and methods of applying the material in a monomer state and then polymerizing it to form a polymer liquid crystal.

The thickness of the polymer liquid crystal composition used in this example is 0.0
The thickness is 5 to 100 μm, and if it is less than 0.05 μm, sufficient resolution as a hologram cannot be obtained, and if it is more than 100 μm, it becomes difficult to perform uniform recording and reproduction in the thickness direction.

Preferably it is within the range of 0.1 to 80 μm.

FIGS. 3(A) and 3(CB) show an embodiment of the recording medium of the present invention. FIG. 3(A) is a plan view of a recording medium according to the present invention, and FIG. 3(B) is a sectional view taken along line AA'.

The cell structure 300 shown in FIGS. 3(A) and 3(B) consists of a pair of substrates 301 made of glass plates, plastic plates, etc.
a and 301b are held at a predetermined distance by a spacer 304, and an adhesive 306 is applied to seal the pair of substrates.
It has a cell structure bonded with a substrate 301a.
A transparent electrode 302a is formed in a predetermined pattern on top of the transparent electrode 302a.

An electrode consisting of a transparent electrode 302b facing the aforementioned transparent electrode 302a is formed on the substrate 301b.

The substrate 301b provided with such a transparent electrode 302b may contain, for example, silicon oxide, silicon dioxide, aluminum oxide,
Inorganic insulating materials such as zirconia, magnesium fluoride, cerium oxide, cerium fluoride, silicon nitride, silicon carbide, boron nitride, polyvinyl alcohol, polyimide, polyamideimide, polyesterimide, polyvaraxylerin, polyester, polycarbonate,
polyvinyl acetal, polyvinyl chloride, polyamide,
It is possible to provide an orientation control TI#A305 film formed using an organic insulating material such as polystyrene, cellulose resin, melamine resin, urea resin, or acrylic resin.

The orientation control film 305 is obtained by forming a film of an inorganic insulating material or an organic insulating material as described above, and then rubbing the surface of the film in one direction with velvet, cloth, or paper.

In another preferred embodiment of the present invention, the alignment control film 305 can be obtained by forming a film of an inorganic insulating material such as SiO or 5in2 on the substrate 301b by oblique vapor deposition.

In another specific example, after forming a film of the above-mentioned inorganic insulating material or organic insulating material on the surface of the substrate 301b made of glass or plastic or on the substrate 301b, the surface of the film is etched by an oblique etching method. Accordingly, an orientation control effect can be imparted to the surface.

It is preferable that the above-mentioned alignment control film 305 also functions as an insulating film, and for this purpose, the alignment control film 305
The film thickness of No. 5 can be generally set in the range of 100 to 1μ, preferably 500 to 5000. This insulating film also has the advantage of being able to prevent the generation of current caused by trace amounts of impurities contained in the liquid crystal layer 303, and therefore does not deteriorate the liquid crystal compound even if the operation is repeated.

Further, in the recording medium according to the present invention, the above-mentioned orientation control film 305
Something similar to this can be provided on the other substrate 301.

To ensure molecular alignment, stretching methods such as -axial stretching, two-wheel stretching, and inflation stretching, and rearrangement by shearing are preferred. For those that do not have film properties and are difficult to stretch when used alone, they can be co-stretched by sandwiching them into a film to obtain a desired orientation.

The polymeric liquid crystal composition according to the present invention is used in an oriented state, and the holographic recording method uses heating of the polymeric liquid crystal composition using the intensity of interference generated by a writing laser beam. Recording is performed by heating to more than the equal phase and rapidly cooling to fix it in the isokyoshi phase, or by disrupting the orientation when it returns to the liquid crystal phase. If it returns to the liquid crystal phase even when heated below the equal phase or above the equal phase,
By applying an electric field, a magnetic field, etc., the alignment direction of the polymer liquid crystal can be changed and recording can be performed.

Next, a description will be given of a method for detecting a shift in focus when the reference light 120 and recording light 119 are focused on the recording means 116 in this embodiment, and a method for correcting the amount of shift at that time.

As shown in FIG. 1(A), the recording light beams 1 to 9 focused on the photoreceptor 114 are reflected and scattered by the photoreceptor 114, return to the original optical path, and are focused by the condenser lens 129, and then the mirror 113 and the half mirror.
121b, and is focused by a condenser lens 123b onto a four-split detector 124b as a light beam 119a.

The same applies to the reference light 120, which is reflected and scattered by the photoreceptor 114, returns to the original optical path, is focused by the condenser lens 108, is reflected by the mirror 105 and half mirror 120a, and is divided into four parts by the condenser lens 123a. Luminous flux 12 to 124a
The light is focused as 0a.

FIGS. 1(B), (C), and (D) show the four-split photodetector 124 for the recording light 119 in this embodiment.
FIG. 4 is an explanatory diagram showing a convergence state when a light beam 119a is incident on the light beam 119b, taking the light beam 119b as an example.

In this embodiment, when the reflected and scattered light 119a is incident on the 4-split photodetector 124b, when the reflected and scattered light is in focus, it is equally focused on each detector as a perfect circle as shown in FIG. 1(B). It looks like this. Due to the shift of the focal point position, the condensed state becomes as shown in Fig. 1 (C) and (D
), and the output of the detector 124b is no longer uniform, so the difference from the in-focus state is detected from this.

The difference detected by the four-segment photodetector 124b is
The focus detection device 127 (125) amplifies the signal, and the focus control lens drive control signal generator 128a (
126) to control the focus control lens drive device 128b (106) and move the condensing lens 129 (mirror 105) to move the recording medium 11.
It becomes possible to focus on 4.

At this time, the same applies to the 4-split photodetector 124a for the reference beam 120, but in this case, the movable mirror 105 is rotated to focus on the recording medium 114.

The following method can be applied as a focus position detection control method in this shrub embodiment.

FIG. 4 shows the off-axis optical method, in which the irradiation beam 31 is incident on the condensing lens 32 while being shifted from the optical axis, and the light beam reflected by the recording medium 34 is divided into two parts according to the focal state. It is arranged to move in the vertical direction of the dividing line of the container 35. Figure 5 shows the configuration of the detector at this time and detector A.

The output signal obtained from B is shown. When the focus matches, the output becomes 0.

FIG. 6 shows a method for detecting a focal position shift using an asymmetric detection method. In this method, a light shielding plate is installed in the path of the reflected light of the irradiation beam, and a part of the light entering the two-split photodetector 35 is blocked depending on the shift in the focal position, thereby detecting the difference in the output of the detector. It is.

FIG. 7 shows a method for detecting a focal position shift using the astigmatism method, and corresponds to a detailed diagram of the method used in FIG. 1(A). By installing a cylindrical lens in the path of the reflected light, if the focal position shifts, it becomes elliptical light, which is detected by a 4-split detector.

FIG. 8 shows a critical angle detection method that applies total reflection of light on a prism surface, and when the focus coincides, the output signals from detectors A and B become equal and the control output becomes 0.

In this embodiment, the positional deviation between the focal point of the reference beam and the recording beam on the recording medium and the track provided on the recording medium,
That is, tracking errors are also detected in the same manner using the configuration shown in FIG. 1(A).

In this embodiment, a recorded portion and a non-recorded portion on the surface of the recording medium are separated and tracks are formed to enable high-speed addressing and further increase in density and capacity.

In this embodiment, tracking error detection methods include, for example, a three-spot method, a push-pull method, a differential push-pull method, and a sample servo method, each of which is used as appropriate depending on the recording medium.

Next, an outline of these detection methods will be explained.

In the three-spot method, as shown in FIG. 9, three laser spots A, B, and C are irradiated onto a recording medium with a phase difference or a difference in light reflectance between recording tracks and non-recording tracks.
Tracking errors are detected by determining the difference in output from the photodetector between laser spots A and C.

In the push-pull method, as shown in Figure 10, the amount of deviation of the laser spot L from the recording track on the recording medium surface is reduced by 2.
A tracking error is detected by obtaining a difference signal (push-pull signal AB) from a two-part photodetector consisting of two photodetectors A and B.

In the differential push-pull method, as shown in FIG. 11(A), three laser spots are created using a grating from the light beam from the laser. Then, each laser spot is arranged so that both side spots on the disk are shifted from the main spot by half the track pitch P in the radial direction, as shown in FIG. The tracking error is detected by detecting the push-pull signal and taking the difference.

As shown in Figure 12, the sample servo method uses 1/4 of the track pitch with different phases or reflectances on the recording medium.
A pair of pits (wobble bits) are used that are radially shifted by a certain amount. Since the signal obtained by sampling the amount of returned light when passing through each dot corresponds to the signal from the side spot of the three-spot method described above, the tracking error is detected by taking the difference between them.

Next, FIGS. 13(A) to 13(D) show an example of the configuration of the recording medium of the recording means according to this embodiment. The figure shows an example of the track shape of a recording medium containing a polymer liquid crystal provided on a transparent substrate.

Further, FIG. 14 shows a schematic diagram of the track shape.

In this example, when the depth of the groove is a, the width of the groove is C, and the width of the land portion of the groove is C, a=0.05 μm to 1 μm% b=
0.5μm~lOOμm, c=0.5μm~100μm
It is said that Especially in this example, a=0.1μm
~0.2μm, b=0.5μm~50μm−, c=1μ
m to 50 μm is preferable.

In addition, in this embodiment, the above three conditions a.

Even if all the values regarding b and c are not satisfied, the predetermined effect can be obtained as long as the depth a of the groove is set within the above range at least within the above conditions. It was also confirmed that the shape of Kiyoshi does not have much influence.

When a recording medium is obtained using the above-mentioned specific disk substrate,
If the polymer liquid crystal layer sandwiched between the substrates is heated to a temperature above the isotropic liquid temperature and slowly cooled for orientation, it is possible to obtain a recording medium that is uniformly oriented in the direction of spiral or concentric grooves. .

FIGS. 15(^) and 15(B) are schematic diagrams of an example of the configuration of a disk according to the present invention. Even in the structure where the recording layer 3 is sandwiched between the grooved substrate 5 on one side and the flat plate 1 on the other side as shown in the cross-sectional views shown in Figures (A) and (B) (see Figure (A)), both sides are grooved. A structure in which the substrate 5 is sandwiched (see FIG. 5B) may be used. As long as at least one of them has the groove shape of the present invention, a recording layer containing well-oriented polymer liquid crystal can be obtained.

Further, the grooves can be formed by a transfer method or injection molding using a stamper. Also, Figure 16 (^).

A disk configuration is also used which allows the application of an electric field as shown in (B). As an example, Figure 16 (
In A), a conductive film 6 such as an ITO vapor deposited film is placed on the flat plate l.
a substrate on which a film 5 having a groove structure is formed;
It has a cross-sectional structure in which a liquid crystal layer 3 is placed between another substrate provided with a conductive film (reflective film) 4. In addition, as another example, in FIG. 16(B), a conductive film is formed on a substrate 5 in which a groove is formed, and a liquid crystal layer is placed between the substrate on which the conductive film is provided as in FIG. 16(A). It has a cross-sectional structure in which 3 are arranged.

In order to perform good tracking using the above-mentioned track in this embodiment, it is desirable to increase the reflection on the recording layer, and for this purpose, it is preferable to provide a semi-transparent thin film (metal film) or the like. At this time, the semitransparent thin film is made of, for example, Au.
, Ag, Cu, A11, or other metals or dielectric thin films are used.

(Effects of the Invention) According to the present invention, when information is recorded by a hologram on a recording medium containing a polymeric liquid crystal, a focus detection means for detecting the focus of a reference beam and a recording beam on the recording medium surface, and correction for focus deviation. By appropriately providing a focus correction means for detecting track errors, a deviation detection means for detecting track errors, and a deviation correction means for correcting track deviations, it is possible to reduce the diameter of the recording portion, making it possible to record with low output as a light source. This makes it possible to record at higher speeds, and since the laser beam can be held accurately in the track area, the number of non-recorded areas can be reduced, resulting in high density, large capacity, and high speed addressing. A playback device can be achieved.

[Brief explanation of drawings]

FIG. 1(A) is a schematic diagram of the main part of an embodiment of the present invention, FIGS. 1(B), (C), and (D) are explanatory diagrams showing the light flux incident on the photodetector according to the present invention, 2 and 3 are explanatory diagrams of a recording medium according to the present invention, FIGS. 4 to 8 are schematic diagrams of an optical system of an embodiment of the focus detection method according to the present invention, and FIGS. 9 to 12 Each figure is a schematic diagram of an embodiment of the tracking error detection method according to the present invention, and each of FIGS. 13 to 16 is a cross-sectional schematic diagram of an embodiment of the recording medium according to the present invention. In the figure, 101 is a laser drive device, 102 is a laser 1
03 is a collimator lens, 104 is a beam separating means, 1
10 is a manual data transfer device, 111 is a shutter array drive circuit, 112 is a shutter array, 113, 105 are mirrors 129, 108 is a condensing lens, 116 is a recording means, 114 is a recording medium, 115 is a substrate, 117 is a light detection 118 is a photodetector signal processing device, 121a
, 121b is a half mirror lens 23a, 123b is a condenser lens, and 124a. 124b is a 4-split photodetector, 128b is a lens drive device, 106 is a mirror drive device, 127.125
is a focus (track) detection device.

Claims (4)

[Claims] (1) A beam separating means for separating a beam from a laser into two beams, a reference beam and a recording beam, an information imparting means for imparting information consisting of intensity modulation to the recording beam, and a means for causing the reference beam and recording beam to interfere with each other. Information recording/reproduction comprising a recording means made of a polymeric liquid crystal recording material for recording the interference, and a reproducing means having a photodetector for detecting diffracted light containing the information generated when the recording means is irradiated with a reference light. In the apparatus, a focus detection means detects a focus shift when the reference light and the recording light are focused on the recording means, and a focus correction means corrects the focus shift based on an output signal from the focus detection means. An information recording/reproducing device comprising: (2) The information recording and reproducing apparatus according to claim 1, wherein the polymer liquid crystal composition of the recording means is made of a material that has been subjected to alignment treatment and that absorbs light from the laser. . (3) A beam separating means for separating the beam from the laser into two beams, a reference beam and a recording beam, an information imparting means for imparting information consisting of intensity modulation to the recording beam, and a means for causing the reference beam and recording beam to interfere with each other. Information recording/reproduction comprising a recording means made of a polymeric liquid crystal recording material for recording the interference, and a reproducing means having a photodetector for detecting diffracted light containing the information generated when the recording means is irradiated with a reference light. In the apparatus, a displacement detection means for detecting a positional displacement between a focal point when the reference beam and the recording beam are focused on a recording medium of the recording means and a track provided on the recording medium; 1. An information recording and reproducing apparatus comprising: a displacement correction means for correcting the positional displacement based on an output signal from the detection means. (4) The information recording and reproducing apparatus according to claim 3, wherein the polymer liquid crystal composition of the recording means is made of a material that has been subjected to alignment treatment and that absorbs light from the laser. .