JPH11273080A - Optical recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct a high speed and high density recording and reproducing without mechanical fine precision by converging laser beams at plural different positions on a recording surface corresponding to the driving current of a semiconductor laser and conducting the recording and the reproducing of information at the plural positions simultaneously. SOLUTION: The driving signals of the semiconductor laser are constituted of the pulse current in which two kinds of pulse trains are superimposed. The first pulse train emits the laser light beams having a peak output power of 100 mW, a duty ratio of 30%, a frequency of 70 MHz and an average output power of 30 mW and the beams are used for the writing on an optical disk. The second pulse train emits the laser light beams having a peak output power of 50 mW, a duty ratio of 10%, a frequency of 50 MHz and an average output power of 5 mW. The optical output powers as well as the beam emitting positions are varied by the operating current of the semiconductor laser and thus these beams converge at different points on the disk. Thus, converging points are arranged on a same track and a writing and a reading are simultaneously conducted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording / reproducing apparatus, and more particularly, to an optical recording / reproducing apparatus capable of simultaneously scanning a plurality of tracks formed on a recording medium.

[0002]

2. Description of the Related Art A recording track (an area in which pits holding information are formed one-dimensionally, hereinafter referred to as a track) formed on an optical recording medium known as an optical disk is formed by a plurality of laser beams. The scanning technique is described in, for example, Japanese Patent Application Laid-Open No. 8-190728.

The optical recording / reproducing apparatus described in this publication is
As shown in FIG. 14, a multi-beam semiconductor laser 501 (the figure discloses a two-beam laser), a collimator lens for converting a plurality of laser beams emitted from the laser beam into parallel light beams
503, a beam forming prism 504 for shaping each of the plurality of parallel light beams into a circular beam, and an objective lens 505 for condensing the plurality of parallel light beams formed into the circular beam as a plurality of spots on a recording medium (optical disk) 506. It has an optical system. The optical disk 506 is arranged so that its periphery is irradiated with the laser beam from the optical system, and a rotating device (not shown) provided at the center of the optical disk 506 causes the laser spot from the optical system to appear as if the periphery of the laser beam is emitted from the optical system. The optical disk is rotated so as to go around the optical disk (FIG. 14 shows the optical disk viewed from the side). The laser beam is circularly polarized and the recording medium
The laser beam radiated to 506 and reflected by the recording medium enters the beam forming prism 504 while maintaining the polarization state, is converted into linearly polarized light here, and then is partially polarized beam splitter provided therein. The light is guided by 507 to a side having a light receiving element (not shown).

The laser beams emitted from the black circle portion and the white circle portion of the end face of the multi-beam semiconductor laser 501 are separately applied to tracks (not shown) formed on the recording medium 506 via the optical system. . The irradiation mode of the laser light is such that the optical system and the rotating device of the recording medium 506 are arranged such that the laser light from the black circle is irradiated with the laser light from the white circle after a predetermined time. The method of recording information on the recording medium 506 by irradiation of the data and reproducing the recorded information by the irradiation of the latter (simultaneous writing with the leading beam and confirmation of the writing content with the succeeding beam), At the same time, there is a variation in that information is recorded or reproduced at high speed by simultaneously irradiating the laser beam. In addition, the tilt (tilt) / spacer 502 provided on the multi-beam semiconductor laser 501 is used for a collimator lens 5 of a plurality of laser beams.
The relative focus position with respect to 03 is corrected by slightly moving the end face position of the multi-beam semiconductor laser 501.

[0005]

In the above prior art, the only means for separating signals of different tracks read out by two laser beams is spatial separation of the detecting elements. For example, a quadrant light receiving element (QPD, Quadrant Photodiode) used in a conventional optical information recording / reproducing apparatus is used.
Even if ode) is used, the purpose is to detect a focus error from one light source in the first place.
It is extremely difficult to separate and detect light emitted in parallel on the order of m.

For this reason, control of the beam condensing position with respect to the optical element for detection requires control of about the stripe interval of the multi-beam semiconductor laser, and a high degree of adjustment is required when detecting the laser beam. In order to reduce the cost of the optical recording / reproducing apparatus, a simpler method that does not require such adjustment is desired.

[0007]

According to the present invention, there is provided a semiconductor laser having a function of condensing laser light at a plurality of different positions on a recording surface by a method of driving a semiconductor laser. The laser light applied to each laser light condensing position should be pulsed light of different frequencies sufficiently higher than the following speed of the recording medium, and the pulsed light should not be irradiated in time overlap. It is devised to drive an optical recording / reproducing device.

As one of means for changing the light emitting position, a semiconductor laser having a function of changing the light emitting position according to the amount of injected current is used, and a pulse current having a peak value corresponding to each recording position is optimized for recording and reproducing information. It has been devised that recording and reproduction are performed by energizing at a duty ratio that becomes an average energy density.

[0009] Not only semiconductor lasers having such special functions but also ordinary array-type semiconductor lasers, if the duty ratio of the pulse current is set to 10% or less, are arrays whose emission positions are sufficiently close to each other. However, the present inventors have also devised that an optical recording / reproducing apparatus having a high speed and a high recording density can be provided without causing a problem of thermal mutual interference. Thermal interference of the semiconductor laser is caused by an increase in threshold current due to a temperature rise due to heat generated by energization of the semiconductor laser. When the semiconductor laser is driven by a low-duty, high-output pulse, the energy conversion efficiency of the semiconductor laser increases as the output increases, so that the amount of heat generated for obtaining the same average power decreases. In addition, the change in the optical output-current characteristics of the semiconductor laser due to temperature is mainly an increase in the threshold current, which also has the effect of reducing the change in the differential luminous efficiency. Low duty pulse driving has a great effect in preventing crosstalk. Have. In this optical recording / reproducing apparatus, reproduced signals from different light condensing points are detected by the same light receiving element and are separated by a frequency filter circuit to reproduce information. Therefore, signals need to be spatially separated as in the prior art. And an inexpensive device configuration was possible.

Based on the above discussion, the present invention provides a semiconductor laser, which is a light source for oscillating a plurality of laser beams, means for supplying a drive current to the semiconductor laser, a recording medium having an optical recording surface, An optical recording / reproducing apparatus having an optical system for condensing a plurality of laser beams emitted from a laser on an optical recording surface, respectively, and recording medium holding means for holding the recording medium and controlling its position with respect to the optical system. And a function of condensing laser light on a plurality of different positions on the recording surface by a driving current supplied to the semiconductor laser from the driving current supply means, and simultaneously recording information on the plurality of positions. Optical recording / reproducing device (also referred to as optical information processing device) having a basic feature of performing and reproducing
I will provide a. As a desirable mode, each of the plurality of laser beams irradiated to the plurality of laser beam condensing positions is a pulse beam of a different frequency sufficiently higher than the following speed of the recording medium, and the pulse beams are temporally different. It is recommended to avoid overlapping irradiation.

As an example of a desirable embodiment, the semiconductor laser has a function of changing a light emission position (oscillation position of laser light) according to an injection current amount, and supplies a pulse current having a peak value corresponding to each recording position. Recording and reproduction are performed by energizing at a duty ratio that provides an optimum average energy density for recording and reproduction of information. In this case, it is recommended that the pulse current supplied as the drive current to the semiconductor laser has a duty ratio of 10% or less.

[0012] Further, combinations of the constituent elements desirable for realizing the above-mentioned optical recording / reproducing apparatus are as follows.

The first point is that the reproduced signals from the different condensing points on the recording medium are detected by the same light receiving element and separated by a frequency filter circuit to reproduce information.

The second point is that the plurality of laser light irradiation positions are set one after another on the same track of the optical disk, and the laser light preceding the disk rotation is used for writing information.
The laser light output of the former is set higher than that of the latter so that the succeeding laser beam is used to confirm the written information.

The third point is that the plurality of laser beams are oscillated as three laser beams modulated at three different frequencies, and the three laser beams extend in the axial direction of the tracks of the optical disk with the rotation of the optical disk. By arranging to scan on the line of the interval and detecting the signal of each spot by frequency, the two spots at both ends of the line of the equal interval are detected.
The control is performed so that the center line coincides with the center line of the track using the book signal.

The entire contents of the optical recording / reproducing apparatus of the present invention described above will be clearly described in the following embodiments of the present invention.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of an optical recording / reproducing apparatus according to the present invention will be described with reference to the following Examples 1 to 3 and respective related drawings.

<Embodiment 1> An optical recording / reproducing method according to a first embodiment of the present invention will be described with reference to FIGS. First, the structure of the semiconductor laser used in this embodiment is shown in FIGS. Reference numeral 101 denotes a GaAs substrate.
The substrate 101 may be (100) just or (100)
Having a plane orientation inclined in the [011] direction from the
1 μm thick made of n _0.5 (Ga _0.3 Al _0.7 ) _0.5 P
A degree of n-type cladding layer 102 is deposited. This n
The undoped In _0.5 (Ga
An active layer 104 sandwiched between light guide layers 103 made of _0.3 Al _0.7 ) _0.5 P is provided. The active layer 104 may be any light emitting layer, for example, a structure having a uniform structure such as a double hetero structure or a structure having energy modulation such as an MQW structure can be used. is there.

On the light guide layer 103, p-type In0.5
A p-type cladding layer 105 made of (Ga _1-x Al _x ) _0.5 P and having a thickness of about 1 μm and a p-type In _0.5 Ga _0.5 P cap layer 1
06 is provided. The central portion of the p-type cladding layer 105 is formed in a ridge (ridge) 107. The p-type cladding layer 105 of such a ridge structure 107 can be formed by using a normal etching technique, and confine light in a horizontal direction by the ridge structure. On the upper surface of the ridge structure 107, there is provided an energized region 108 whose axis is shifted from the ridge structure by about 2 μm.
Type current block layer 109.

On the n-type current block layer 109 and the p-type cap layer 106, a p-side electrode 111 made of an Au—Zn alloy is provided via a p-type contact layer 110 made of p-type GaAs. Further, on the back surface of the GaAs substrate 1, an n-side electrode 112 made of an Au.Ge alloy is provided. Each of the above semiconductor layers is grown and formed by using a CVD method such as the MOCVD method. Further, as shown in FIG. 2, the current injection region 10 whose center axis is shifted from the ridge structure 107 is formed.
8 can be easily manufactured by forming a photoresist mask for forming a ridge and a silicon oxide mask for forming a current injection region in a self-aligned manner by using side etching of silicon oxide. A wafer having such a structure was cleaved to a length of about 600 μm to form a laser chip. When the current flowing in the current-carrying region is changed, the refractive index at this portion becomes asymmetric with respect to the waveguide having the ridge structure, so that the beam is bent according to the current injection amount. Operating current is 50 mA,
The distribution of the laser beam intensity at 65 mA and 80 mA was as shown in FIG. 3. As the operating current increased, the light emitting position moved to the right and the light output increased almost in proportion to the current. .

Next, the configuration of an optical recording / reproducing apparatus using the present semiconductor laser will be described with reference to FIGS.
As shown in FIG. 4, in the optical recording / reproducing apparatus of this embodiment, a laser beam 102 emitted from a semiconductor laser 101 is used.
(Wavelength 630 nm) is converted into parallel rays by the collimator lens 115 and the elliptic correction prism 116 and the beam splitter 1
After passing through optical components such as 17, 1/4 wavelength plate 118,
The light is focused on the recording medium by the focusing lens 119. The optical recording medium has a structure in which land portions (convex portions) 121 and groove portions (concave portions) 122 repeat at intervals of 0.6 μm as shown in FIG. 5, and information is recorded on both the land portions and the groove portions. . The optical recording medium 120 was rotated at 1800 rpm, condensed by a condenser lens 119 (aperture ratio: 0.55), and irradiated onto the optical recording layer.

The drive signal of the semiconductor laser is composed of a pulse current (pulse train 1 + 2) obtained by stacking two types of pulse trains (pulse trains 1 and 2) as shown in FIG. The first pulse train has a peak output of 100 mW and a duty ratio of 30.
%, A frequency of 70 MHz and an average output of 30 mW are used for writing on an optical disk. The second pulse train was irradiated with laser light having a peak output of 50 mW, a duty ratio of 10%, a frequency of 50 MHz, and an average output of 5 mW. These beams are condensed at different points on the disk because not only the light output but also the beam emission position changes depending on the operating current of the semiconductor laser. In this embodiment, the semiconductor lasers are arranged so that the beam with the average output of 30 mW and the beam with the average output of 5 mW are irradiated on the same track so that the beam of 30 mW precedes.

The signal processing for recording and reproduction by this apparatus was performed as follows. The recording information 123 is first stored in the code conversion circuit 1.
24, code-converted and converted into digital information. The digital information is converted by the modulation circuit 125 into a pulsed laser drive signal synchronized with the 70 MHz clock signal generated by the clock generation circuit 126. On the other hand, the read pulse train is
The pulsed laser drive signal synchronized with the 50 MHz clock signal generated in step 6 is superimposed on the write signal. The laser drive circuit 127 drives the laser according to the laser drive signal thus obtained. At the time of signal detection, it is necessary to read the read signal separately from the write signal, and in the present embodiment, the signal separation was performed using the difference between the modulation frequencies of the parents. The read signal detected by the detector 128 is amplified by the detection circuit 129, and the detection signal is amplified by the band-pass filter 13 synchronized with the reproduction pulse.
The reproduced signal is separated by 0. The reproduction signal is binarized by each reproduction circuit 131, becomes reproduction digital information, is sent to a code conversion circuit 132, and is code-converted. The outputs of both reproduction circuit systems are combined to obtain final reproduction information 133. Get

<Embodiment 2> As a second embodiment of the present invention, an example in which tracking of an optical disk is performed using the semiconductor laser of the present invention will be described with reference to FIGS.

The semiconductor laser structure used in the optical recording / reproducing apparatus of this embodiment has a structure substantially similar to that used in the first embodiment. Operating current of this semiconductor laser is 50
FIG. 7 shows the distribution of the laser beam intensity when driven at mA, 65 mA, and 80 mA. The light emitting position moves to the right and the light output increases almost in proportion to the current as the operating current increases. Was obtained.

As shown in FIG. 8, such a semiconductor laser is
90MHz, peak power 50mW, duty ratio 10%
(Pulse train 1), 70 MHz, peak output 6
A pulse (pulse train 2) with 5 mW and a duty ratio of 8%;
Pulses of three different frequencies, that is, a pulse (pulse train 3) having a frequency of 50 MHz, a peak output of 80 mW, and a duty ratio of 6% were driven by pulse currents accumulated in the same manner as in the first embodiment. The waveform is not shown). As a result, the laser light is condensed for each frequency at three slightly shifted points on the optical disk as shown in FIG.

The outline of the optical recording / reproducing apparatus of this embodiment is shown in FIG.
As shown in FIG. 0, it is almost similar to that of the first embodiment (see FIG. 4) (therefore, the description of the components common to the first embodiment is omitted). However, there is a major difference in the usage (function) from the first embodiment.

As shown in the schematic diagram of FIG. 10, the laser light reflected from the optical disk is converted into an electric signal by a photodetector, and this electric signal is subjected to a frequency filter synchronized with the clock frequency as in the first embodiment. And separated for each frequency. Of the separated signals, 90 MHz and 50 MHz signals are used as tracking error detection signals, and 70 MHz signals are used as read signals.

Further, in this embodiment, a function of finely adjusting the tracking by optimizing the peak output and the duty ratio of the 70 MHz signal is added. As the recording density of optical discs has increased, the spacing between tracks on which information has been recorded has become narrower. As a result, conventional optical discs required two position control mechanisms for rough position control and precise position control. According to the embodiment, only a rough mechanical position control mechanism is required, so that the cost can be reduced, and the time response of position control is also faster than in the past. Furthermore, according to this device, the position of the light beam for obtaining the tracking signal can be controlled not by the characteristics of the components such as the beam splitter but by the electric signal, so that the optical disc of the old specification in which the track interval is set to various values is used. On the other hand, there is also an advantage that an optimum tracking beam interval can be obtained by appropriately setting the pulse peak output and the duty ratio. Further, according to this method, it is possible to vibrate the beam irradiation position on the track and use this vibration as a tracking position detection signal.

<Embodiment 3> As a third embodiment of the present invention, a plurality of semiconductor laser light sources are used in an optical recording / reproducing apparatus using a pulse-modulated semiconductor laser as in the first embodiment. An example in which higher-speed information reproduction is made possible by changing the frequency of the data.

FIG. 11 shows the structure of the semiconductor laser used in the present invention. In this structure, a GaN buffer layer 302 is grown on a sapphire substrate (C-plane) 301 to a thickness of about 200 Å, and an n-type GaN layer 303 and an n-type Ga
_0.8 Al _0.2 N clad layer 304, n-type GaN optical guide layer 30
5, InGaN active layer 306, p-type GaN light guide layer 3
07, p-type Ga _0.8 Al _0.2 N cladding layer 308, p-type GaN
The cap layer 309 was sequentially grown. Next, this p-type G
A stripe-shaped SiO ₂ mask is formed on the surface of the aN layer 309 by using ordinary gas phase chemical deposition and photolithography, and p-type Ga _0.8 Al _0.2 N is formed by reactive ion etching using the SiO ₂ as a mask. The cladding layer 308 is removed. Next, the p-type Ga remaining in the ridge shape
_The layer above the _0.8 Al _0.2 N cladding layer 308 is buried with an AlN film 310 formed by magnetron sputtering and a polyimide resin 311, and the ridge tip is exposed by etch-back of the polyimide resin to form an AlN film 310 again.
Was etched by reactive ion etching to form a waveguide and a current path in a self-aligned manner. Next, in order to take out the anode electrode, etching is performed to reach the GaN layer 303 in a part of the wafer other than the light emitting region, and the n-GaN layer 303 and the p-type GaN cap layer 30 are formed.
9, a tungsten electrode 312 was formed on the surface, and a vertical end face was formed by a reactive ion beam etching method to obtain a semiconductor laser structure. Further, when an AlN coating film 313 is formed on this vertical end face by reactive ion beam evaporation, a good window structure can be formed by the mixed crystal of nitrogen-based semiconductors at the end face part. No phenomena were seen.
Thus, the present semiconductor laser was able to perform a pulse operation up to an optical output of 500 mW. In the semiconductor laser of this example, such a semiconductor laser having a stripe shape was formed with a stripe width of 2 μm and a stripe interval of 6 μm. One of the stripes of the present semiconductor laser is set to 50 MHz and the light output is set to 300 m.
W, driven by pulse light of duty ratio 2.0%, the other one is 30MHz, light output 450mW, duty ratio 1.7%
And the same optical recording as in Example 1 was performed. In the case of the present embodiment, the duty ratio was 10% and 6.7% even during writing because the output of the semiconductor laser was large, and 2% and 1.3% during reading.

The outline of the optical recording / reproducing apparatus of this embodiment is shown in FIG.
As shown in FIG. 2, the arrangement of a plurality of laser beam irradiation positions on the optical disk is substantially the same as in the first and second embodiments,
The difference is that the angle is changed by about 90 °. That is, when the laser light emitted from the semiconductor laser is condensed on the optical disk by the optical system having the structure shown in the schematic diagram of FIG. 12, the difference in the position of the light emitting point in the semiconductor laser causes the difference in the position of the optical disk as shown in FIG. Appear radially, so that the laser light is focused on separate tracks on the optical disc. The reflected light from each track is separated into signals by frequency by the signal processing circuit shown in FIG. 12 in the same manner as in the first and second embodiments to obtain reproduction information.

Since the energy conversion efficiency of the semiconductor laser increases as the output increases, and the characteristic change of the semiconductor laser due to the temperature change mainly appears in the threshold current, the output fluctuation rate due to the temperature change decreases as the output increases. Works advantageously to suppress the thermal interaction between the stripes, and even if the interval between the stripes is only 6 μm, there is almost no thermal interaction between the stripes at the time of reading and writing, and good recording and reproducing characteristics can be obtained. Was.

[0034]

According to the present invention, a high-speed and high-density optical recording / reproducing apparatus can be formed without requiring precise mechanical precision.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of a semiconductor laser according to a first embodiment of the present invention.

FIG. 2 is a top structural view of the semiconductor laser according to the first embodiment of the present invention.

FIG. 3 is a spectrum diagram showing a shift of an injection current and a light emission position (horizontal axis) in the semiconductor laser according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram of an optical recording / reproducing apparatus according to a first embodiment of the present invention.

FIG. 5 is a schematic diagram showing a manner of irradiating an optical disc (recording medium) with laser light according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram of a drive current pulse supplied to the semiconductor laser according to the first embodiment of the present invention. The actually supplied current is a pulse train 1 + 2 in which pulse trains 1 and 2 are superimposed. The horizontal axis indicates time.

FIG. 7 is a spectrum diagram showing a shift of an injection current and a light emission position (horizontal axis) in a semiconductor laser according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram of a drive current pulse supplied to a semiconductor laser according to a second embodiment of the present invention. A drive current obtained by superimposing the illustrated pulse trains 1, 2, and 3 is supplied to the semiconductor laser. The horizontal axis indicates time.

FIG. 9 is a schematic diagram showing a manner of irradiating an optical disc (recording medium) with laser light according to a second embodiment of the present invention.

FIG. 10 is a schematic diagram of an optical recording / reproducing apparatus according to a second embodiment of the present invention.

FIG. 11 is a sectional structural view of a semiconductor laser according to a third embodiment of the present invention.

FIG. 12 is a schematic diagram of an optical recording / reproducing apparatus according to a third embodiment of the present invention.

FIG. 13 is a schematic view showing a manner of irradiating an optical disc (recording medium) with laser light according to a second embodiment of the present invention.

FIG. 14 is a schematic diagram of an optical system of a conventional optical recording / reproducing apparatus.

[Explanation of symbols]

101: Multi-beam semiconductor laser, 102: Laser beam, 103: Collimator lens, 104: Elliptical correction prism, 105: Beam splitter, 106: 1/4 wavelength plate, 107: Condensing lens, 108: Polycarbonate substrate, 109 ... on a recording medium, 110 ... recording information, 111 ...
Code conversion circuit, 112 laser driving circuit, 113 detector, 114 detection circuit, 115 code conversion circuit, 1
16 ... reproduction information 117 ... GaAs substrate 118 ... n-type In0.5 (Ga0.3 Al0.7) 0.5P cladding layer 11
9: Undoped In0.5 (Ga0.3 Al0.7) 0.5 P light guide layer, 120: active layer, 121: p-type In0.5 (G
a1-x Alx) 0.5 P cladding layer, 122 ... p-type GaAs
s cap layer, 123 ridge structure, 124 energized region, 125 n-type current block layer, 126 p-type contact layer, 127 p-side electrode, 128 n-side electrode, 129
... Clock circuit, 130 modulation circuit, 131 low-pass filter, 132 reproduction circuit, 201 sapphire substrate (C plane), 202 GaN buffer layer, 203 n-type GaN layer, 204 n-type Ga0.8Al0 .2N cladding layer, 20
5 ... n-type GaN light guide layer, 206 ... InGaN active layer,
207: p-type GaN optical guide layer, 208: p-type Ga0.8Al
0.2N clad layer, 209 ... p-type GaN cap layer, 21
0: AlN film, 211: polyimide resin, 212: tungsten electrode.

Claims (7)

[Claims] An optical recording / reproducing apparatus having a semiconductor laser as a light source, means for supplying a drive current to the semiconductor laser, and an optical system for condensing laser light emitted from the semiconductor laser on an optical recording surface. The semiconductor laser has a function of condensing laser light at a plurality of different positions on the recording surface by a driving current of the semiconductor laser, and simultaneously records and reproduces information on the plurality of positions. Optical recording and reproducing device. 2. The laser light applied to the plurality of laser light condensing positions is pulsed light of different frequencies sufficiently higher than the following speed of a recording medium, and the pulsed light is irradiated overlapping in time. An optical recording / reproducing apparatus characterized by not being performed. 3. The semiconductor laser according to claim 1, wherein a light emitting position has a function of changing according to an injection current amount, and a pulse current having a peak value corresponding to each recording position is converted into an average energy optimum for recording and reproducing information. An optical recording / reproducing apparatus which performs recording and reproduction by energizing at a duty ratio which becomes a density. 4. An optical recording / reproducing apparatus according to claim 2, wherein the pulse current has a duty ratio of 10% or less. 5. The optical recording / reproducing apparatus according to claim 1, wherein the reproduced signals from the converging points are detected by the same light receiving element and separated by a frequency filter circuit. An optical recording / reproducing apparatus for reproducing information. 6. An optical recording / reproducing apparatus according to claim 1, wherein said plurality of laser beam irradiation positions are set successively on the same track of a light disk.
An optical recording / reproducing apparatus, wherein a laser beam preceding a disk rotation is used for writing information, and a subsequent laser beam is used for confirming the written information. 7. An optical recording / reproducing apparatus according to claim 1, wherein three laser beams modulated at three different frequencies extend in the axial direction of the track as the optical disk rotates. It is arranged to scan on the line of the interval, and by detecting the signal of each spot by frequency, the center line coincides with the center line of the track using the two signals at both ends of the line of the equal interval An optical recording / reproducing apparatus characterized in that the optical recording / reproducing apparatus is controlled so as to perform