JPH01287825A - Optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To detect a defect at the information recording time by forming a reproducing signal by operating the respective reflection light of the 2nd beam following the non-recording part of the information recording medium preceding from a 1st beam and the 3rd beam following the information recording medium of after recording by succeeding from the 1st beam and comparing the recording signal and reproducing signal. CONSTITUTION:The dividing means 31 for dividing the beam 30 of a semiconductor laser 29 into the 1st beam 32 having the optical strength of a recording level, the 2nd beam 33 and 3rd beam 34 located before and behind the last beam for the information recording direction of the above of an information recording medium 9 and having a low enough optical strength more than this 1st beam 32 is provided. The 1st, 2nd and 3rd respective beam reflected by the information recording medium 9 is individually detected by the optical detector 40 having plural light receiving faces, a reproducing signal is obtd. by operating the output signal obtd. from the respective light receiving face 40e, 40f detecting the 2nd beam 33 and 3rd beam 34 by reproducing signal generating means 45, 23A and is compared with a recording signal. The detection reliability of the recording defect is thus increased economically by using an ordinary one beam semiconductor laser 29.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical recording and reproducing device that detects defects during information recording, and particularly relates to an optical recording and reproducing device that is economical and has excellent recording defect detection reliability. It is something.

[Prior Art] Optical recording and reproducing apparatuses that use optical means such as laser beams to concentrically or spirally record and reproduce information on a rotating disk-shaped information recording medium are well known. This type of device has the advantage that it is capable of high-density recording and has a large recording capacity compared to magnetic disk devices. However, on the other hand, since information recording media have more defects than magnetic disks, they require a function to ensure the reliability of recorded information.

For this reason, one possible method is to rotate the information recording medium on which information is recorded once and detect the reproduced signal to determine the presence or absence of an information recording defect, but this method has the disadvantage that it takes the time equivalent to one rotation to detect the defect. be. To prevent this, in recent years, optical recording and reproducing devices that can detect reproduced signals in real time have been considered.

FIG. 7 is an optical path diagram showing a conventional optical recording/reproducing device, which is described, for example, on pages 108 to 112 of the collection of papers of "Optical Memory Symposium '85".

In the figure, (1) is a two-beam semiconductor laser that has two light sources, and as shown in Figure 8, it emits a recording beam (2) and a reproduction beam (3) that are parallel to each other. It has become. Although an array-type two-beam semiconductor laser (1) having two active regions in the -device is shown here, any device that can drive each beam (2) and (3) independently may be used. , a structure in which two normal elements each having one active region are arranged in parallel may be used.

(4) is a collimator lens placed on the beam output side of the two-beam semiconductor laser (1), and (5) is a collimator lens (N beam splitter) placed to receive the beam that has passed through the collimator lens (4). , (6) are reflecting mirrors for directing the beam transmitted through the extinction beam splitter (5) upward.

(7) is a quarter-wave plate, (8) is an objective lens, and (ku) is an information recording medium placed close to the objective lens (8). 8) is placed between the reflecting mirror (6) and the information recording medium (9). (io) is a guide groove formed along the information recording direction of the information recording medium (9), and (11) and (12) are each beam (2) and (12) irradiated along the guide groove (10).
These are the recording spot and the reproduction spot formed by 3).

(13) is a half prism that splits the beam reflected by the polarizing beam splitter (5) into reflected light and transmitted light;
14) is a two-split photodetector that has two light receiving surfaces (14a) and (14b) and receives the beam transmitted through the half prism (13).

(15) is a convex lens that converges the beam reflected by the half prism (13), and (16) is a pin that has a pinhole (17) that allows only the reproduction beam (3) to pass among the beams from the convex lens (15). Hall mirror, (18)
is a half prism that splits the reproduction beam (3) that has passed through the pinhole (17), and (19) is a half prism (
(18) is a knife placed on the optical path of the reproduction beam (3) that has passed through, (20) is the two light-receiving surfaces (ZQa)
and (20b), and is a two-split photodetector that receives the reproduction beam (3) via the knife (19).

(21) is a photodetector that receives the recording beam (2) reflected by the pinhole mirror (16), and (22) is a photodetector that receives the reproduction beam (3) reflected by the half prism (18). A photodetector (23) that generates a reproduced output C is a reproduced signal detection circuit for obtaining a reproduced signal from the reproduced output C from the photodetector (22).

(24) is a recording signal generation circuit that outputs the recording signal A as a pulse train, and (25) is a driver circuit that drives the two-beam semiconductor laser (1) based on the recording signal A.

(26) is a differential amplifier that detects the output signal of the two-split photodetector (14), and each light receiving surface (14a) and (14b
) is being input. (27) is a differential amplifier that detects the output signal of the two-split photodetector (20), into which the output signals from each of the light receiving surfaces (20a) and (20b) are input.

The two-split photodetector (14) and the differential amplifier (26) constitute a well-known tracking error detection optical system called a push-pull method. The dynamic amplifier (27) constitutes a well-known focusing error detection optical system called the Knifezi method.

FIG. 9 shows a recording spot (11) on an information recording medium (9).
) and a reproduction spot (12) in detail. Here, we have shown a case in which recording and reproduction is performed by irradiating the spots (11) and (12) between the guide grooves (10), but recording and reproduction by irradiating them onto the guide grooves (10) is also shown. In Figure 9, l is the distance between the recording spot (11) and the following reproduction spot (12), the arrow is the direction of rotational movement of the information recording medium (9), and (28) is the recording spot ( 11) on the information recording medium (9).

Next, the operation of the conventional optical recording/reproducing apparatus shown in FIGS. 7 to 9 will be described with reference to the timing chart shown in FIG.

First, when a recording signal A as shown in FIG. 10 is generated,
Based on this recording signal A, the 2-beam semiconductor laser (1)
is driven. The recording beam (2) and reproduction beam (3) emitted from the 2-beam semiconductor laser (1) are turned into parallel beams by a collimator lens (4), and then passed through a polarizing beam splitter (5) and a reflecting mirror (6). , an information recording medium (
9), and a recording spot (
11) and a reproduction spot (12).

The recording spot (11) contains recording information (for example, pulse width) of the recording signal A, and pits (28) having a shape B corresponding to this are sequentially formed on the information recording medium (9).

On the other hand, the reproducing spot (12), which follows the recording spot (11) by the distance pH, is driven with a constant light intensity, and the reproducing spot (12) is driven with a constant light intensity, and the written pit (28) is (several microseconds) later, it will start playing.

That is, the recording spot (11) is reflected at the same time as the pit (28) is formed, and the reproduction spot (12) is reflected at the pit (28) after writing. Information recording medium (
The recording beam (2) and the reproduction beam (3) reflected by the objective lens (8) and the quarter-wave plate (7)
), but since the polarization direction is rotated by 90° by reciprocating through the quarter-wave plate (7), it is reflected by the polarizing beam splitter (5).

Subsequently, each beam (2) and (3) is connected to a half prism (
13), but some of it is reflected by the half prism (13).
3) and is input to the tracking error detection optical system, where it is used to correct the tracking error of the beam irradiated onto the information recording medium (9).

Each beam (2) and (3) reflected by the half prism (13) is converged by a convex lens <15), and then the recording beam (2) is reflected by a pinhole mirror (17),
The reproduction beam (3) passes through the pinhole (16) and is reflected by the half prism (18). At this time, a part of the reproduction beam (3) passes through the half prism (18) and is input to the focusing error detection optical system, and is used to correct the focusing error of the beam irradiated onto the information recording medium (9). used.

The recording beam (
2) is received by the photodetector (21) and detected as a pulse waveform corresponding to the recording signal A, and the information recording medium (9)
It is also used to determine the presence or absence of obstacles such as optical paths.

On the other hand, the reproduction beam (3) reflected by the half prism (18) is received by the photodetector (22) and detected as reproduction output C corresponding to pit shape B as shown in FIG. The reproduced signal is subjected to waveform processing by the reproduced signal detection circuit (23) and detected as a pulse train-shaped reproduced signal. The reproduced signal thus obtained is compared with the recorded signal A and used to determine whether there is a defect in the information recording.

Here, a case has been shown in which the reflectance of the information recording medium (9) decreases due to the formation of pits (28), but the reflectance of the information recording medium (9) increases due to the pits (28).
), the information recording state can be determined in the same way.

Note that although the reproduced signal A is delayed by a time t1 with respect to the recorded signal A, since the time t1 is on the order of several microseconds, it is considered that the presence or absence of a recording defect can be determined almost in real time.

When reproducing information recorded on the information recording medium (9), a reproduction beam (3) is emitted from the 2-beam semiconductor laser (1).
) only needs to be emitted and detected by the reproduction signal detection circuit (23).

[Problems to be Solved by the Invention] As described above, conventional optical recording and reproducing devices have problems with information recording media (
Since the reflected beam from the recording beam (3) was separated and detected as the reproduction beam (3), the optical system was complex and required a large number of optical components, and strict placement accuracy was required for each optical component. Since it is necessary to use a 2-beam semiconductor laser (1) that can independently drive the (2) and reproduction beam (3), it is required to have uniform optical characteristics such as oscillation wavelength and radiation shape. There was a problem that it was not only economical but also that the detection reliability deteriorated.

This invention was made to solve the above-mentioned problems, and aims to provide an optical recording/reproducing device that is economical and highly reliable in detecting recording defects.

[Means for Solving the Problems] An optical recording/reproducing apparatus according to the present invention includes a semiconductor laser that emits one beam modulated by a recording signal, and a first beam having a recording level optical intensity. , a dividing means for dividing into a second beam and a third beam having a sufficiently lower light intensity than the first beam and located before and after the first beam with respect to the information recording direction on the information recording medium; and an information recording medium. A photodetector having a plurality of light-receiving surfaces for individually detecting the first beam, second beam, and third beam reflected by A reproduced signal generating means for calculating an output signal to obtain a reproduced signal is provided.

Further, an optical recording/reproducing apparatus according to another aspect of the present invention includes a semiconductor laser that emits one beam modulated by a recording signal, a first beam having a recording level optical intensity, and a first beam having a recording level optical intensity. a second beam whose light intensity is sufficiently lower than that of the first beam and which precedes the first beam with respect to the information recording direction on the information recording medium; and a first beam reflected by the information recording medium and a second beam; A photodetector having a plurality of light-receiving surfaces for individually detecting beams, a matching means for matching each output signal obtained from the light-receiving surface, and calculating each output signal after matching to obtain a reproduced signal. A reproduced signal generating means is provided.

[Operation] In the present invention, a second beam precedes the first beam and follows the unrecorded portion of the information recording medium, and a third beam follows the first beam and follows the recorded information recording medium. A reproduction signal is generated by calculating each reflected light beam, and the recording signal and reproduction signal are compared to detect defects during information recording.

Further, in another aspect of the present invention, a reproduction signal is generated by calculating each reflected light of a first beam and a second beam that precedes the first beam and follows an unrecorded portion of the information recording medium. Then, the recorded signal and the reproduced signal are compared to detect defects during information recording.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings. 1st
The figure is an optical path diagram showing one embodiment of this invention.
) and (25^) correspond to the reproduced signal detection circuit (23) and the driver circuit (25), and (4) to (10) and (24) are the same as described above.

(29) is a semiconductor laser that emits one beam (30). (31) is a diffraction grating placed on the beam output side of the semiconductor laser (29), and is a dividing means for dividing the beam (30) along the direction of the guide groove (10) of the information recording medium (9). It consists of Although the drawing shows a case where the diffraction grating (31) is placed between the collimator lens (4) and the polarizing beam splitter (5), the diffraction grating (31) is placed between the semiconductor laser (29) and the collimator lens (4). May be placed.

(32) to (34) are the first to third beams divided by the diffraction grating (31), the first beam (32) located in the center is the 0th-order beam with high light intensity, and the beams located on both sides The second beam (33) and the third beam (34) are
The +1st order beam and the -1st order beam have low light intensities and are equal to each other. In addition, the first beam (32) and the second beam (
33) and the third beam (34) can be arbitrarily set depending on the design of the diffraction grating (31).

(35) to (3)) are the first spots formed on the information recording medium (9) by each beam (32) to (34).
As shown in Fig. 2, the second spot (36) and the third spot (37) are located on both sides of the first spot (35) at an equal distance l. ing. Therefore, the second spot (36) has a distance of 1l11
only the first spot (35) precedes the third spot (35), and the third spot (35)
37) is behind the first spot (35) by a distance.

<38) is reflected by the information recording medium (9), and each beam (
A lens for converging the beams (32) to (34), and (39) each beam (32) to (34) that has passed through the lens (38).
It is a cylindrical lens that converges in one direction.

(40) is a six-segment photodetector having six light-receiving surfaces (40a) to (40f), and the first beam (
32) is incident on the first light receiving surface (40e), a second beam (33) is made incident on the second light receiving surface (40f), and a third beam (34) is made incident on the second light receiving surface (40f).

(41) is an adder for calculating the sum of each output signal a to d from the four light receiving surfaces (40a) to (40d).

(42) is the difference (a+c) between the sum signal (a+e) of output signals a and C and the sum signal (b+d) of output signals S and d.
The output FS of this operational amplifier (42) is used as a focusing error detection signal based on the astigmatism method.

(43) is the difference (a + d - b) between the sum signal (a + d) of output signals a and d and the sum signal (b + c) of output signals S and C.
-c), and this operational amplifier (
The output TS of 43) is used as a tracking error detection signal using the push-pull method.

(45) is a divider that divides the output signal f of the second light receiving surface (40f) by the output signal e of the first light receiving surface (40e),
The output signal G (=f/e) of this divider (45) is input to the reproduced signal detection circuit (23A). The divider (45) and the reproduced signal detection circuit (23A) constitute reproduced signal generating means for generating the reproduced signal H by calculating the output signals e and f.

Next, while referring to the timing chart diagram in Figure 3,
The operation of the embodiment of the present invention shown in FIGS. 1 and 2 will be described.

When reproducing information that has already been recorded, the semiconductor laser (29) is driven at a constant reproduction level A0, and the first
A first spot (35) of the beam is irradiated onto the bit (28).

The first beam (
32) to the four light receiving surfaces (4) of the six-segment photodetector (40).
0a) to (40d), and the output E of the adder (41)
is the playback signal.

When newly recording information, a beam (30) modulated according to the recording signal A is emitted from the semiconductor laser (29). This beam (30) is split by a diffraction grating (31) at a predetermined ratio of light intensity, and is divided into a first beam (32>
, a second beam (33) and a third beam (34).

Among these, the pulse train of the first beam (32) at the center with high light intensity is represented by the recording output A', and includes a modulation pulse portion at the recording level A and a reproduction level A. (see Figure 3), while the second beam (3
3) and the pulse train of the third beam (34) have a recording output A
', and is always at playback level A. Therefore, the first spot (35) forms the bit (28) on the information recording medium (9), and is sufficiently low to the extent that it does not impede the formation of the bit (28). The second spot (36), which precedes the spot (35) by a distance l, always follows the unrecorded part of the information recording medium (9), and also follows the unrecorded part of the information recording medium (9).
- The third spot (37) is a distance l behind (35).
) tracks on the recorded bit (28).

When the first spot (35) is irradiated onto the information recording medium (9), a pulse train of recording level A sequentially forms bits (28) of shape B shown with diagonal lines in FIG.

Furthermore, since the second spot (36) receives the same light intensity modulation as the first spot (35), the first light receiving surface (40
The level of the output signal e in e) is similar to that of the recording output A'.

On the other hand, the third spot (37) is the recorded bit (2
8) In order to track the top, the level of the output signal f of the second light receiving surface (40f) is set to
It fluctuates as shown in the figure.

That is, since the reflectance of the bit (28) is low, the reflected light intensity of the third beam (34) decreases when the third spot (3)) is located at the recording part of the bit (28).
), it becomes the same level as the output signal e. In this way, the light intensity change corresponding to the shape B of the bit (28) is superimposed on the output signal f of the second light receiving surface (40f) that detects the reflected third beam (34). At this time, the timing at which the third spot (37) irradiates the bit (28) is delayed by a time t1 corresponding to the distance l from the first spot (35).

The divider (45) normalizes the output signal f by dividing it by the output signal e, and extracts only the modulated signal portion of the bit (28) included in the output signal f to obtain the output signal G.

Finally, the reproduced signal detection circuit (23^) is connected to the divider (45).
) is subjected to waveform processing and a reproduced signal H consisting of a pulse train is output. As is clear from FIG. 3, this reproduced signal H matches the recorded signal A before time tX if there is no defect in the information recording.

Thereafter, by comparing the recorded signal A and the reproduced signal H in the same way as described above, it is possible to determine whether or not information is correctly recorded on the information recording medium (9).

In this way, by using a normal semiconductor laser (29) and dividing one beam (30) into multiple beams (32) to (34) using a diffraction grating (31), it is possible to Parts are no longer needed.

In the above embodiment, the reproduced signal generating means was constituted by the divider (45) and the reproduced signal detection circuit (23A).
As shown in FIG. 4A, a differential amplifier (46) that takes the difference between the output signals e and r is inserted on the input side of the divider (45), and the difference signal (e-f) between the output signals e and r is obtained. It is also possible to divide by the output signal e.

In this case, the output signal G of the divider (45) is G,
= (e-f)/e = 1-f/e = 1-G, resulting in the waveform shown in Fig. 4B. Therefore, like the output signal G described above, the output signal G1 is obtained by extracting only the modulated signal component based on the bit (28) included in the output signal f. If this output signal G1 is waveform-shaped by a reproduction signal detection circuit (23A), a reproduction signal H similar to that described above is obtained, and it can be determined from this whether information recording is being performed correctly.

Next, without using the third beam (34), the first beam (32) and the second beam (33) are used to generate the reproduced signal H.
An embodiment of another invention of the present invention will be described.

FIG. 5 is an optical path diagram showing an embodiment of another invention of the present invention, in which (4) to (10), (23A L(24),
(25A), (29) to (39), (41) to (43
) and (45) are the same as above. In addition, each spot (35) to (3) formed on the information recording medium (9)
The positional relationship of 7) is as shown in the second section.

(50) is a three-part photodetector having five light-receiving surfaces (50a) to (50e), and the first beam ( 3
2) is incident, and a second beam (33
) is set to be incident.

44) is an amplifier for amplifying the output signal e of the light receiving surface (50e), and constitutes matching means for matching the level of the output signal F of this amplifier (44) with the output signal E of addition 3 (41). are doing. The output signal F of the amplifier (44) is input to a divider (45), which divides and normalizes the output signal E of the adder (41).

Further, the amplifier (44), together with the divider (45) and the reproduced signal detection circuit (23A>), includes a reproduced signal generating means for calculating the output signals E and F whose levels match each other to generate the reproduced signal H. It consists of

Next, the operation of another embodiment of the present invention shown in FIG. 5 will be described with reference to the timing chart of FIG. 6 and FIG. 2.

Similarly to the above, the first beam (32) is connected to the information recording medium (9).
), information is reproduced and recorded, but the detailed operations will not be explained here because they are redundant.

When recording information, the first spot 35) forms a bit (28) on the information recording medium (9), and the first spot 35) forms a bit (28) on the information recording medium (9).
The second spot (36
) always follows the unrecorded part of the information recording medium (9), and
The third spot (37) follows on the recorded bit (28) (see FIG. 2).

When the first spot (35) is irradiated onto the information recording medium (9), bits (28) of shape B shown by diagonal lines in FIG. 6 are sequentially formed by a pulse train of recording level A+. Therefore, the level of the output signal E of the adder (41) corresponding to the reflected light intensity of the first beam (32) varies depending on the shape B of the bin (28).

That is, since the reflectance of the bit (28) is low, the reflected light intensity of the first beam (32) gradually decreases as the bit (28) is formed, and furthermore, when one recording pulse ends, the recording level Even if the playback level becomes A0 from A, while the first spot (35) is irradiating a part of the bit (28), the reflected light intensity decreases to below the playback level AO.
When the bit (28) is completely passed, the playback level is A.

becomes.

On the other hand, since the second beam (33) is also subjected to light intensity modulation like the first beam (32), the level of the output signal e of the light receiving surface (50e) that detects the reflected light of the second beam (33) is is similar to the recording output A'.

Here, the amplifier (44) amplifies the output signal e with a pre-adjusted amplification degree, and makes the output signal F the same level as the recording output A'. As a result, the level of the output signal F matches the level of the output signal E of the adder (41).

The divider (45) normalizes the output signal E of the adder (41) by dividing it by the output signal F of the amplifier (44), and divides only the modulated signal due to the bit (28) included in the output signal E. The output signal G2 (=E/F) is obtained by extraction.

Finally, the reproduced signal detection circuit (23A) includes a divider (45
) is subjected to waveform processing and a reproduced signal H consisting of a pulse train similar to that described above is output. Thereafter, by similarly comparing the recorded signal A and the reproduced signal H, it is determined whether the information is correctly recorded on the information recording medium (9).

In this case, the second spot (36) that follows the unrecorded area precedes the first spot (35) for recording, and the aforementioned delay time tρ is used to detect the recording state at the same time as the bit (28) is formed. This eliminates the need for real-time defect detection.

It goes without saying that in this embodiment as well, a differential amplifier (46) similar to that shown in FIG. 4A can be inserted on the input side of the divider (45), and a similar reproduced signal H can be obtained.

Furthermore, as a matching means, an amplifier (44) for amplifying the output signal e was used, but an attenuator (not shown) for attenuating the output signal E of the adder (44) was inserted, and the output of the attenuator The signal may be divided by the output signal e.

Furthermore, in each of the above embodiments, an example was shown in which the astigmatism method was used as the focusing error detection optical system and the push-pull method was used as the tracking error detection optical system, but it is also possible to apply to other detection means. Needless to say, in this case, depending on the detection means, the first beam (3
2) The shape of the light receiving surface of the photodetector that detects the second beam (33) and the third beam (34) may be changed.

Furthermore, an information recording medium (
Although the case 9) has been described, the same effect can be achieved even if the information recording medium is of a type in which the reflectance increases.

[Effects of the Invention] As described above, according to the present invention, there is provided a semiconductor laser that emits one beam modulated by a recording signal, a first beam having a recording level optical intensity, and a semiconductor laser that emits one beam modulated by a recording signal.
a splitting means for splitting the beam into a second beam and a third beam whose light intensity is sufficiently lower than that of the beam and which are located before and after the first beam with respect to the information recording direction on the information recording medium; A photodetector has a plurality of light-receiving surfaces for individually detecting the first beam, the second beam, and the third beam, and calculates output signals obtained from each light-receiving surface for detecting the second and third beams. Since a reproduction signal generating means for obtaining a reproduction signal is provided, an ordinary 1-beam semiconductor laser can be used, and an optical recording and reproduction apparatus that is economical and highly reliable in detecting recording defects can be obtained. There is.

According to another aspect of the present invention, there is a first beam having a recording level optical intensity, and a first beam having a sufficiently lower optical intensity than the first beam and preceding the first beam with respect to the information writing direction on the information recording medium. a photodetector having a plurality of light-receiving surfaces for individually detecting the first beam and the second beam reflected by the information recording medium; and a light-receiving surface. A matching means for matching each output signal obtained from the 1st beam and a reproduction signal generating means for calculating each output signal after matching to obtain a reproduction signal are provided. Since the reproduction signal is generated based on the respective reflected lights of the second beam and the first beam that follow the unrecorded area of the recording medium, a normal 1-beam semiconductor laser can be used, which is economical. Moreover, there is an effect that an optical recording/reproducing apparatus with high accuracy in detecting recording defects can be obtained.

[Brief explanation of the drawing]

Fig. 1 is an optical path diagram showing one embodiment of the present invention, Fig. 2 is an explanatory diagram showing the position of each spot in Fig. 1, and Fig. 3 is an optical path diagram showing an embodiment of the present invention.
Timing chart diagram for explaining the operation of the figure, No. 4
8 and 4B are block diagrams showing other embodiments of the reproduced signal generating means in FIG. 1 and timing charts showing its operation, and FIG. 5 shows another embodiment of the present invention. 6 is a timing chart for explaining the operation of FIG. 5, FIG. 7 is an optical path diagram showing a conventional optical recording/reproducing device, and FIG. 8 is a 2-beam semiconductor in FIG. 7. FIG. 9 is an explanatory diagram showing the irradiation position of each spot in FIG. 7, and FIG. 10 is a timing chart diagram for explaining the operation of FIG. 7. (9) Information recording medium (23A) Reproduction signal detection circuit (29) Semiconductor laser (30) Beam (31) Diffraction grating (splitting means) (32) ...First beam (33)...Second beam <34)...Third beam (40)...Six-segment photodetector (40a) to (40f>-light receiving surface (44)... Amplifier (matching means) (45)...Divider (50)...Five division photodetector (50a) to <50e)...Light receiving surface A...Record signal H...Reproduction signal fl
1! ! 9: Info record chant body 29: Inscription stick - sign 30: Hime 31: Lu FT grade' + (Kai Liu Yodan) 32: Kiku 1 Hime 33: Fuji 2 Beam 34: 3rd Heem 4o : Hole 5T split light inspection gain 40a~40f: Light receiving surface No. 251 No. 3! ! Figure 6 at the end of Figure 4A: 1 Figure 7 ■ Figures 8 and 9 Figure 10

Claims (1)

[Claims] (1) A semiconductor laser that emits one beam modulated by a recording signal; A first beam having a recording level optical intensity; dividing means for dividing into a second beam located before the first beam and a third beam located after the first beam with respect to the information recording direction of the information recording medium; a photodetector having a plurality of light receiving surfaces for individually detecting the first beam, the second beam and the third beam; and a photodetector having a plurality of light receiving surfaces for individually detecting the first beam, the second beam and the third beam; an optical recording/reproducing apparatus, comprising: reproduction signal generating means for calculating an output signal of and obtaining a reproduction signal, and detecting a defect during information recording based on the recording signal and the reproduction signal. (2) a semiconductor laser that emits a single beam modulated by a recording signal; a second beam preceding the first beam with respect to the information recording direction; and a dividing means for individually detecting the first beam and the second beam reflected by the information recording medium. a photodetector having a plurality of light-receiving surfaces, a matching means for matching each output signal obtained from the light-receiving surface, and a reproduced signal generating means for calculating each of the matched output signals to obtain a reproduced signal. An optical recording/reproducing apparatus, comprising: detecting defects during information recording based on the recording signal and the reproduction signal.