JPH08203079A - Write test method and optical information recording device - Google Patents

Abstract

(57) [Abstract] [Purpose] Even if the recording power is controlled by multilevel control, it is possible to set the recording power to an optimum value simply and accurately. A write test method for performing test recording on a magneto-optical disc 1 and setting a recording power of a light beam to an optimum value, which is a low process power level PL and a high process power pre-recorded on the disc 1. Level P
H, and a step of reading the degree Oth of the thermal interference degree, a step of obtaining the level of the multilevel control signal of the light beam based on the read information, and calculating a ratio of these multilevel control signals, While keeping the ratio constant, the recording power of the light beam is changed to record a predetermined test writing pattern on the disc 1, and each time the test writing pattern is recorded, the test writing pattern is reproduced to detect the asymmetry of the reproduction signal. , Determining the optimum power of the light beam based on the detection result of the asymmetry.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a write test method and an optical information recording apparatus for performing test recording on an optical information recording medium to adjust the recording power of a light beam to an optimum value.

[0002]

2. Description of the Related Art Conventionally, a magneto-optical memory has been known as an optical memory capable of erasing recorded information, and an information recording / reproducing apparatus using the magneto-optical memory has been put into practical use at present.
When recording information in such a magneto-optical memory, it is possible not only to perform high-density recording as compared with the recording method to the magnetic memory, but also to record and reproduce information without contacting the information recording surface. Has an advantage. However, on the other hand, the information is recorded by heating the recording layer of the recording medium by irradiating it with a light beam and changing the magnetization of the heated portion. It is necessary to uniformly magnetize in one direction. Therefore, in order to record information in the magneto-optical memory, two processes, an erasing process and a recording process, are required, and there is a problem that the recording speed becomes slow.

In order to solve such a problem, there is a method in which erasing and recording are shared by separate optical heads and carried out at the same time, but with this method, the scale of the apparatus becomes large and the cost becomes high. . Therefore, there is a so-called overwriting recording method in which new information is overwritten on previously recorded old information without passing through an erasing process. As one of the overwrite methods, there is known a light modulation overwrite method in which a magneto-optical recording medium made of an exchange-coupling laminated film is used, and the power of an irradiation light beam is changed according to recording information to perform overwrite. There is. In such an optical modulation overwrite method, two types of laser powers P _H and P _L are used for overwriting recording.
Is used, the erasing process is performed by the relatively low laser power P _L , and the recording process (domain wall formation) is performed by the relatively high laser power P _H.

Further, recently, in addition to such an increase in information recording speed, there is a great demand for a higher density for increasing the amount of information. Therefore, in order to meet such demands, a track pitch of a recording medium is narrowed, recording pits are shortened, and a pit edge recording method is considered as a method of recording information. However, for that purpose, a laser control technique for controlling a semiconductor laser used as a light source with high accuracy is required, and at present, recording power is controlled by three-value and four-value laser power control. Further, since the stability of the recording pits changes due to the fluctuation of the device temperature and the variation of the medium sensitivity, and the recording performance of the device also changes, it is necessary to perform a write test (test writing) to adjust the laser power.

[0005]

As described above, when recording information at a high density by pit edge recording or the like, it is important to adjust the recording power by the write test in order to secure the recording performance. However, in the currently valid three-value and four-value laser power control, when adjusting the three-value and four-value laser powers, since the adjustments are made independently, the write test becomes complicated. was there.

The present invention has been made in view of the above-mentioned conventional problems. An object of the present invention is to set the recording power to an optimum value simply and accurately even if the recording power is controlled by multi-valued control. An object of the present invention is to provide a write test method and an optical information recording device which can be performed.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is a write test method for performing test recording on an optical information recording medium and setting the recording power of a light beam to an optimum value, which is previously recorded on the recording medium. The low process power level, the high process power level, and the degree of thermal interference are read, and the level of the multilevel control signal of the light beam is obtained based on the read information. A step of calculating the ratio of the value control signals, and recording a predetermined test writing pattern on the recording medium by changing the recording power of the light beam while keeping this ratio constant, and each time the test writing pattern is recorded. Reproducing the test writing pattern, detecting the asymmetry of the reproduction signal, and determining the optimum power of the light beam based on the detection result of the asymmetry. It is accomplished by write test method according to claim and.

Another object of the present invention is an optical information recording apparatus for recording information by controlling the recording power of a light beam on an optical information recording medium by multilevel control, which is pre-recorded on the information recording medium. Low process power level,
A means for obtaining the level value of the multilevel control signal of the light beam based on the power level of the high process and the degree of thermal interference, and a means for calculating the ratio of this multilevel control signal, and keeping this ratio constant. Means for recording a predetermined test writing pattern on the recording medium by changing the recording power of the light beam, means for detecting the asymmetry of the reproduced signal of the recorded test writing pattern, and the light based on the detection result of the asymmetry. And a means for setting the optimum power of the beam.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the optical information recording apparatus of the present invention. In FIG. 1, reference numeral 1 denotes a magneto-optical disk which is an information recording medium, and is rotated at a predetermined speed by driving a spindle motor 2. A bias magnet 3 for applying a bias magnetic field is disposed on the upper surface of the magneto-optical disk 1, and a magneto-optical disk 1 is irradiated with a light beam facing the bias magnet 3 on the lower surface. An optical head 4 for detecting the reflected light of is provided.

A semiconductor laser 5 as a light source is provided in the optical head 4, and a light beam emitted from this laser 5 is reflected by a polarization beam splitter 6 and enters an objective lens 7. Then, the light beam is focused by the objective lens 7,
An image is formed on the magneto-optical disk 1 as a minute light spot. A part of the light applied to the magneto-optical disk 1 is reflected by the disk surface, passes through the objective lens 7 again, passes through the polarization beam splitter 6, and enters the polarization beam splitter 9. This incident light is split into an S-polarized component and a P-polarized component by the polarization beam splitter 9, and the split light is detected by the optical sensors 10 and 11, respectively. Optical sensor 10, 11
The differential detection signal is detected by the differential amplifier 12 and reproduced as a magneto-optical signal.

An actuator 8 for driving the objective lens 7 in the tracking direction and the focus direction is provided in the optical head 4. Further, in the present embodiment, although not shown in FIG. 1, an error signal generation circuit for detecting a tracking error signal of a light beam and a focus error signal, and a servo control circuit for performing tracking control and focus control are provided. It is provided. The error signal generation circuit generates a tracking error signal and a focus error signal based on the reflected light from the magneto-optical disk 1, and the servo control circuit operates the actuator 8 based on the tracking error signal and the focus error signal obtained. To drive. As a result, the objective lens 7 is driven in the tracking direction and the focus direction, and the light beam from the semiconductor laser 5 with which the magneto-optical disc 1 is irradiated is focused on the disc surface so as to follow the information track for scanning. Controlled as. In this way, tracking control and focus control are performed.

The reproduced signal obtained by the differential amplifier 12 is sent to the signal processing circuit 17 and subjected to predetermined signal processing to generate reproduced data. The asymmetry detection circuit 13 is a circuit for detecting the asymmetry of the reproduction signal. As will be described later in detail, the asymmetry detection circuit 13 detects the degree of asymmetry of the reproduction signal of the test writing pattern during the write test, and based on that, the semiconductor The optimum power of the laser 5 is adjusted. C
The PU 16 constitutes a main control circuit of the optical information recording apparatus of this embodiment, and controls the semiconductor laser drive circuit 14 and the bias magnet drive circuit 15. The semiconductor laser drive circuit 14 supplies a drive current to the semiconductor laser 5 under the control of the CPU 16, and the bias magnet drive circuit 15 supplies a drive current to the bias magnet 3 under the control of the CPU 16. In this way, the CPU 16 controls recording / reproduction of information by controlling each unit. As will be described later in detail, the CPU 16 controls each part to perform a write test when the magneto-optical disk 1 is exchanged, etc., and performs control to set the recording power of the semiconductor laser 5 to the optimum power.

Next, an embodiment of the write test method of the present invention will be described. First, in this embodiment, when the write test is performed, the semiconductor laser 5 is turned on with a waveform as shown in FIG. 2A shows a recording signal, and FIG.
2B shows a PH1 control signal, FIG. 2C shows a PH2 control signal, and FIG. 2D shows a cutoff level control signal. Figure 2
The recording signal (a) is a signal supplied from the CPU 16 to the semiconductor laser drive circuit 14. When the recording signal is supplied to the semiconductor laser drive circuit 14, FIG.
PH1, PH2 and the cutoff level control signals as shown in (c) and (d) are supplied to the semiconductor laser 5,
Lights up with the power as shown in FIG. Therefore, in this embodiment, the semiconductor laser 5 is controlled by four values of PH1, PH2, PL1 and Pr. The value of Pr is constant.

On the magneto-optical disk 1, PL1, P
It is unlikely that the values of H1 and PH2 change independently of each other, except for the control error of the semiconductor laser drive circuit 14.
The control error of this drive circuit is negligible.
Therefore, the change of the power of the semiconductor laser 5 on the magneto-optical disk 1 is due to the temperature change in the apparatus, the dirt of the objective lens, and the like, and PL1, PH1, and PH2 have a constant ratio (PL
It may be considered that the values change in conjunction with keeping 1: PH1: PH2).

Therefore, the inventor of the present application has made PL1: PH1: P
An experiment was conducted to measure the window margin and the degree of asymmetry by changing the recording power (Pw) of the semiconductor laser 5 while keeping the ratio of H2 constant.
The results shown in FIG. 3 were obtained. In FIG. 3, asymmetry indicates the symmetry of the reproduction signal, and the asymmetry of 0 is the optimum power. Further, when the recording power is changed, the window margin changes as shown in FIG. 3, and it can be seen that the recording power at which the window margin becomes maximum coincides with the recording power at which the asymmetry becomes zero. That is, it is possible to find the optimum value of the recording power by measuring the asymmetry of the reproduction signal. Therefore, in this embodiment, the recording power of the semiconductor laser 5 is set to the optimum power based on the asymmetry of the reproduction signal based on such an idea.

Next, a specific method of setting the recording power in the write test to the optimum value will be described. FIG.
3 is a flow chart showing the flow of processing during a write test. The write test may be performed every time the magneto-optical disk 1 is replaced, may be performed before recording information, or may be performed periodically at regular intervals. In FIG. 4, when performing a write test,
The CPU 16 uses the optical head 4 to access the medium information area (track in which the medium control information is recorded) of the magneto-optical disk 1 (S1), and the low level power (PL) and high level recorded in advance in the medium information area. Power (PH) of
The value of the degree of thermal interference (Oth) is read (S2). These pieces of information are reproduced by the signal processing circuit 17 and taken into the CPU 16.

Here, the values of PL, PH, and Oth described above are recorded in advance in each medium information area for each disk, but it is desirable to determine these values as follows. First, for PL, a 2T continuous signal is recorded with the optimum recording power obtained from the sensitivity curve of the disc, and then the laser beam is irradiated in DC to determine the power at which the 2T signal is completely erased as PL. . It can be observed with a spectrum analyzer whether it has been completely erased.

Regarding the PH, a signal having a frequency sufficiently slower than the normal recording signal, for example, a frequency of about 500 KHz and a duty of about 90% (mostly DC irradiation) was recorded on the disk, and the carrier started. Alternatively, the power at which the recording noise starts to increase is determined as PH.

Finally, regarding Oth (degree of thermal interference),
It is determined by the following formula determined by the standard.

Oth = 100 · (| L ₈ −L ₄ −4T |) / T (%) (1) L _{8 in the} equation (1) is the length of 8T of the reproduced signal, and L ₄ is 4T of the reproduced signal. The length of 4T is an ideal length of 4T. In this way, the 8T and 4T signals are recorded, and the 8
Oth is determined by measuring the lengths of T and 4T and calculating from the obtained results using the formula (1).

The test patterns at this time are 2T (M), 2T (S), 2T (M), 2T.
(S), 2T (M), 2T (S), 2T (M), 2T
(S), 2T (M), 8T (S), 4T (M), 8T
(S), 8T (M), 8T (S) may be used. M is a mark and S is a space. However, when recording a mark, all recording should be performed by shortening by 0.5T. Specifically, 2T is 1.5T, 4T is 3.5T, and 8T is 7.5T.
And record it. Furthermore, when reproducing the test pattern and measuring the lengths of 4T and 8T of the reproduced signal,
The slice level is set to an intermediate value between the peak level and the bottom level of the reproduction signal, and when recording the test pattern, the power at which the length of 4T is ideal is set as the recording power. In this way, PL and P for each disc
The values of H and Oth are obtained and recorded in the respective medium information areas.

Returning to FIG. The CPU 16 sets P based on the values of PL, PH, and Oth read from the magneto-optical disk 1.
L1, PH1, and PH2 are calculated (S3). These values can be uniquely determined by the thermal structure of the disk, the linear velocity, and the recording laser lighting pattern. That is, PL1 = f ₁ (PL, PH, Oth) PH1 = g ₁ (PL, PH, Oth) PH2 = h ₁ (PL, PH, Oth) can be obtained as a function. More concretely expressing this function, PL1 = m (PH-PL) PH1 = nPH-PL1 PH2 = (1 + L · Oth) PH1. However, 0 <m <1. Also, n and L differ depending on the laser lighting pattern. Therefore, by obtaining this function at the time of designing the device, it is possible to obtain appropriate values of PL1, PH1, and PH2 according to the combination of the device and the disk from the information of PL, PH, and Oth.

Next, in the CPU 16, PL1, PH1, P
PL when calculating the ratio of H2 and starting the light test
Initial values of 1, PH1 and PH2 are set (S4). This initial value is set to a low power, for example, and then gradually increased by a predetermined amount. Thus, the preparation for the write test is completed, and the process for searching the optimum power is subsequently performed. In order to search for the optimum power, a trial writing pattern is recorded in a predetermined area of the magneto-optical disk 1 with the initial values of PL1, PH1 and PH2 set previously (S5), and then the trial writing pattern is reproduced to reproduce the reproduction signal. Whether or not the recording power is the optimum power is determined according to the degree of asymmetry (S6). That is, the asymmetry detection circuit 13
Detect the asymmetry of the playback signal with
Output to U16.

The CPU 16 determines whether or not the degree of asymmetry is 0. If the asymmetry is not 0, it is determined that the recording power is not the optimum value, and PL1, PH
While keeping the ratio of 1 and PH2 constant, the recording power is increased by one step to update the recording power (S7). Then, a test writing pattern is recorded again in a predetermined area of the magneto-optical disk 1 with the updated recording power (S5), and then the test writing pattern is reproduced and asymmetry of the reproduction signal determines whether the recording power is optimum. Is performed (S6). In this way, the processes of S5 to S7 are repeated, and PL1, PH
The recording power is increased stepwise while keeping the ratio of 1 and PH2 constant. Then, the asymmetry detection circuit 13
PL1, PH1, PH2 when the detection result of is 0
The value of is determined as the optimum power (S8). As described above, the optimum power is determined by the write test, and thereafter information is recorded on the disc with the obtained recording power.

Here, when the write test is performed, the test writing pattern is, for example, n × (8) as shown in FIG.
When the T-2T) -8T-8T-nx (2T-8T) pattern is used, asymmetry can be easily measured. FIG. 5 shows a reproduction signal when such a test writing pattern is reproduced, FIG. 5A shows a reproduction signal when the recording power is underpower than the optimum value, and FIG. 5B shows a recording power. The reproduction signal when the recording power is the optimum power, and FIG. 5C shows the reproduction signal when the recording power is the overpower than the optimum value. Also, paying attention to the 2T signal in the figure,
As is clear from a comparison with FIG. 7, the laser is turned on below the center line and 2T pits are recorded on the medium.

When the recording power is an under power rather than the optimum value, comparing the amplitudes of 2T, the amplitude on the side where the 2T pit exists (recording side) is large as shown in FIG. The amplitude on the nonexistent side becomes smaller. Further, if the recording power is the optimum value, the amplitude of 2T on the side where the pit exists and the amplitude on the side where the pit does not exist become equal, as shown in FIG. Further, when the recording power is overpower than the optimum power, the amplitude of 2T on the side where pits exist is small and the amplitude of 2T on the side where no pits exist is large as shown in FIG. 5C. Therefore, it is necessary to record such a test writing pattern on a disc, detect the amplitude of 2T on the side where the 2T pit does not exist in the reproduction signal, and detect the amplitude of 2T on the side where the 2T pit exists and compare them. It is possible to detect the asymmetry of the reproduction signal.

FIG. 6 shows a specific example of the asymmetry detection circuit 13 that can be applied when the test writing pattern as described above is used. In FIG. 6, an AGC (auto gain controller) 20 is a circuit for making the amplitude level of the reproduction signal constant, a peak hold circuit 21 is a circuit for detecting the peak level of the reproduction signal, and a bottom hold circuit 22 is the bottom of the reproduction signal. This is a circuit that detects the level. When the output signals of the peak hold circuit 21 and the bottom hold circuit 22 are input to the differential amplifier 23 and differentially detected, the amplitude value of the reproduction signal can be obtained. The output signal of the differential amplifier 23 is output to the A / D converter 24, and the A / D converter 24 is configured to digitize the amplitude value of the reproduction signal at the timing of the sampling clock.

FIG. 7 shows the timings of the trial writing pattern and the sampling clock. The trial writing pattern is described as a pattern in which asymmetry can be easily measured as described above. N × (8T-2T) -8T-8T-n ×
It is a (2T-8T) pattern. This corresponds to FIG. 5 and corresponds to the side from the beginning 8T to 2T, 8T, 2T, 8T where there is no 2T pit in FIG. 5, and the subsequent 8T,
2T, 8T, 2T, and 8T correspond to the side where the 2T pit exists in FIG. When such a test writing pattern is used, 2T is generated on the side where the 2T pit exists and the side where the 2T pit does not exist.
Since it is only necessary to detect the amplitude of, the sampling clock may be output at a timing of 10T × n + 8T. Therefore, if the sampling clock is output as shown in FIG.
2 on the side where the 2T pit exists from the A / D converter 24
The amplitude of T and the amplitude of 2T on the side where there is no 2T pit can be obtained, and the asymmetry of the reproduction signal can be detected by the ratio of the obtained amplitudes.

When the inventor of the present application conducted an experiment in which information was recorded with the optimum power obtained by the method of FIG. 4 by using the four-valued laser control signal as described in FIG. 2, a good result was obtained. I was able to get it. That is, the rotation speed of the magneto-optical disk is 3600 rpm, and the recording position is the innermost circumference (r = 2
4.0 mm), PL1 = 4.5 mW, PH1 =
When recording was performed with a recording power of 11.0 mW and PH2 = 12.0 mW, stable recording with a minimum pit length of 0.75 μm could be performed. The wavelength of the semiconductor laser is 7
The NA of the objective lens was 80 nm and was 0.55. Also,
At this time, the window margin was 50% or more under the assumption of an error rate of 10 ⁻⁵ , and a good result was obtained.

Since the value of the recording power and the width of the cutoff pulse are determined by the medium structure of the magneto-optical disk, the compatibility between the mediums can be ensured by deciding the parameters by performing the test recording. .

Next, a second embodiment of the present invention will be described. FIG. 8 shows a laser control pattern of this embodiment. The level of the PH1 control signal in FIG. 8B and the pattern of the PH2 control signal in FIG. 8C are different from those in the first embodiment, and the optical output of the semiconductor laser 5 is correspondingly different from that in FIG.
The recording power is as shown in (e). In this embodiment, since the laser lighting pattern changes, PL1, P
The values of H1 and PH2 naturally change. Specifically, a function from the values of PL, PH, and Oth read from the disk, PL1 = f ₂ (PL, PH, Oth) PH1 = g ₂ (PL, PH, Oth) PH2 = h ₂ (PL, PH , Oth). The rest is the same as in the first embodiment, and the optimum power may be found in the flowchart of FIG.

Also in this embodiment, when the inventor of the present application conducted a recording experiment with the optimum power by the above write test, good results could be obtained. That is, PL1 = 4.5 mW and PH1 = 1 at the recording position of the innermost circumference (r = 24.0 mm) at a disk rotation speed of 3600 rpm.
When recording was performed with a recording power of 1.0 mW and PH2 = 10.0 mW, stable recording with a minimum pit length of 0.75 μm could be performed. In this embodiment, the first
The recording power may be slightly smaller than that in the embodiment.

Next, a third embodiment of the present invention will be described. FIG. 9 is a diagram showing a laser lighting pattern of this embodiment. The cutoff level control signal of FIG. 9D is different from that of the first embodiment, and accordingly the recording power of the semiconductor laser is different as shown in FIG. 9E. In this embodiment,
As is apparent from FIG. 9D, since the cutoff pulse is inserted before and after the recording signal, the power level of the low process is raised, and thereby the recording power can be lowered.

In this embodiment, P recorded on the disc is used.
A function, PL1 = f ₃ (PL, PH, Oth) PH1 = g ₃ (PL, PH, Oth) PH2 = h ₃ (PL, PH, Oth) may be obtained from the values of L, PH, and Oth. The rest is the same as in the first and second embodiments.
Find the optimum power in the flowchart.

Also in the present embodiment, according to the experimental result of the inventor of the present application, the optimum power (PL1 = PL1 =
6.0 mW, PH1 = 10.0 mW, PH2 = 10.5
It was confirmed that stable recording with a minimum pit length of 0.75 μm can be performed under the conditions of mW), disk rotation speed of 3600 rpm, and recording position at the innermost circumference (r = 24.0 mm) of the disk.

Next, a fourth embodiment of the present invention will be described. FIG. 10 is a diagram showing a laser lighting pattern of this embodiment. The pattern of the PH2 control signal and the pattern of the cutoff level control signal are different from those of the first embodiment as shown in FIG. 10C, and accordingly, the recording power of the semiconductor laser is different as shown in FIG. 10E. There is. In this embodiment, a function is obtained from the values of PL, PH, and Oth read from the disk: PL1 = f ₄ (PL, PH, Oth) PH1 = g ₄ (PL, PH, Oth) PH2 = h ₄ (PL, PH, Oth). Then, after that, the optimum power may be found according to the flowchart of FIG. 4 as in the previous embodiment.

Also in this embodiment, according to the experimental results of the inventor of the present application, the optimum power (PL
1 = 6.0 mW, PH1 = 9.5 mW, PH2 = 10.
0 mW), the number of rotations of the disk is 3600 rpm, and the recording position is the innermost circumference (r = 24.0 mm) of the disk,
It was confirmed that stable recording with a minimum pit length of 0.75 μm could be performed.

In the second to fourth embodiments as well, the value of the recording power and the width of the cutoff pulse are determined by the medium structure of the magneto-optical disk. Therefore, if the parameters are determined by performing the test recording, Compatibility between media can be ensured.

[0039]

As described above, according to the present invention, while the ratio of multi-valued control signals is kept constant, the recording power is changed to perform the trial writing, and the optimum power is determined based on the asymmetry of the reproduced signal. Since the determination is made, there is an effect that the optimum power can be determined easily and with high accuracy even in the recording of information in which the recording power of the light beam is controlled by multilevel control.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of an optical information recording device of the present invention.

FIG. 2 is a diagram showing a laser control signal and recording power in the embodiment of FIG.

FIG. 3 is a diagram showing a relationship between a laser recording power, a window margin, and an asymmetry of a reproduction signal.

FIG. 4 is a flowchart showing an embodiment of the write test method of the present invention.

FIG. 5 is a diagram for explaining a trial writing pattern used for a write test.

FIG. 6 is a block diagram showing a specific example of an asymmetry detection circuit.

FIG. 7 is a diagram for explaining the operation of the asymmetry detection circuit of FIG.

FIG. 8 is a diagram showing a laser control signal and recording power of a second embodiment of the present invention.

FIG. 9 is a diagram showing a laser control signal and recording power of a third embodiment of the present invention.

FIG. 10 is a diagram showing a laser control signal and recording power according to a fourth embodiment of the present invention.

[Explanation of Codes] 1 Magneto-optical disk 2 Spindle motor 3 Bias magnet 4 Optical head 5 Semiconductor laser 7 Objective lens 10, 11 Optical sensor 12 Differential amplifier 13 Asymmetry detection circuit 14 Semiconductor laser drive circuit 16 CPU 17 Signal processing circuit 21 Peak Hold circuit 22 Bottom hold circuit 24 A / D converter

Claims (2)

[Claims] 1. A write test method for performing test recording on an optical information recording medium to set the recording power of a light beam to an optimum value, wherein the power level of a low process pre-recorded on the recording medium is high. A step of reading the power level of the process and the degree of thermal interference, and a step of obtaining the level of the multilevel control signal of the light beam based on the read information and calculating the ratio of these multilevel control signals. While keeping this ratio constant, the recording power of the light beam is changed to record a predetermined test writing pattern on the recording medium, and each time the test writing pattern is recorded, the test writing pattern is reproduced to reproduce the reproduction signal. Detecting the asymmetry, and determining the optimum power of the light beam based on the detection result of the asymmetry. . 2. An optical information recording apparatus for recording information by controlling the recording power of a light beam on an optical information recording medium by multi-valued control, the low-process power level pre-recorded on the information recording medium, A means for obtaining the level value of the multilevel control signal of the light beam based on the power level of the high process and the degree of thermal interference, and a means for calculating the ratio of this multilevel control signal, and keeping this ratio constant. Means for recording a predetermined test writing pattern on the recording medium by changing the recording power of the light beam, means for detecting the asymmetry of the reproduced signal of the recorded test writing pattern, and the light based on the detection result of the asymmetry. An optical information recording apparatus comprising: means for setting an optimum power of a beam.