JPH03230331A - Optical information recording medium and method for recording optical information thereon - Google Patents

Abstract

PURPOSE:To obtain a medium which satisfies the push-pull value, reflectance and modulation degree specified by CD standards by specifying an optical phase difference and film thickness of a light-absorbing layer in a land area. CONSTITUTION:The pregrooves and light-absorbing layer are formed so as to satisfy the relations expressed by formulae II and III. In these formulae, dsub is the distance from the interface 8 between the light-absorbing layer 3 and a substrate 2 in a land area 7 formed on both sides of the pregroove 6 to the bottom of the interface 8 in the pregroove 6, dabs is the distance from the interface 9 between the light-absorbing layer 3 and light-reflecting layer 4 in the land area 7 to the bottom of the interface 9 in the pregroove 6. nsub is the real part of the complex refractive index of the substrate 2, nabs is the real part of the complex refractive index of the light-absorbing layer 3, is the wavelength of reproducing light L2, DELTAS expressed by formula I is the optical phase difference in reproducing light L2 reflected by the light-reflecting layer in the pregroove 6 and in the land area 7, and dln is film thickness of the light- absorbing layer 3 in the land area 7.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical information recording medium and a method for recording optical information on this optical information recording medium, and particularly relates to an optical information recording medium that has translucency and has a pregroove formed therein. An optical information recording medium that is optically writable and readable and has a substrate, a light absorption layer provided on the substrate and made of a dye, and a light reflection layer provided on the light absorption layer and made of a metal film. This invention relates to a method for recording optical information on an optical information recording medium.

[Prior Art] This type of optical information recording medium is produced by forming pits in advance on the above-mentioned light-transmitting substrate using means such as a press, and then coating the surface on which the pits are formed with a metal reflective film. Compact discs (hereinafter referred to as rCDJs) have been put into practical use as playback-only optical information recording media and are widely used.

In addition, optical information recording media are being considered that go beyond such read-only media and allow the user to record information by irradiating the substrate with a laser beam as necessary.

For example, Japanese Patent Application Laid-Open No. 54-89605 has at least a light-transmitting substrate, a light-absorbing layer provided on the substrate and containing a dye, and a light-reflecting layer provided on the light-absorbing layer, An optical information recording medium on which information can be optically written and read is disclosed.

Also, JP-A-58-189851 or JP-A-59-
No. 171,689 and others disclose a method of recording on such an optical information recording medium by deforming a layer adjacent to a light absorption layer.

Furthermore, JP-A-59 No. 135640 or JP-A-59
No. 210546, etc. discloses a method of flattening the light reflective layer side of a light absorbing layer provided on a substrate with pregrooves (hereinafter referred to as "leveling") in order to improve the contrast of reproduced signals obtained from an optical information recording medium. ”) is disclosed.

Furthermore, Japanese Patent Laid-Open No. 63-257931 and the like specify the depth of prepits in optical information recording media having prepits.

However, when using a so-called recordable conventional optical information recording medium that uses dye as the leading plate, a dedicated CD player is required to reproduce the signals recorded on this optical information recording medium. There is a problem in that a new and separate CD player is required and cannot be played on a commercially available CD player, which is generally widely used for playback-only CDs.

Therefore, in order to play a CD on a commercially available CD player, it is necessary to obtain playback (No. A) that complies with the CD standard, which is a globally unified standard.

In order to comply with this CD standard, the reflectance of the light reflecting layer must be 70% or more, the degree of modulation I11/It,op of the variable vR amplitude in the reproduced signal must be 0,
The modulation degree of the modulation amplitude in the reproduced signal must be 6 or more,
The block error rate is 3.0X10~2 or less, and when the push-pull method is used for pit tracking, the push-pull value is 0.04~0.
．． It needs to be 07.

This push-pull value will be described below. For so-called write-once CDs, recording is performed at the same time as reproduction as a premise of obtaining a reproduction signal that satisfies the above-mentioned CD standard. Therefore, in order to record signals specified in the CD standard so that they can be reproduced, it is necessary to enable good tracking even if the CD is in an unrecorded state.

In general, the so-called tracking method, in which the irradiation position of the laser pickup is accurately positioned on the pit row on the CD so that the recording and playback laser beams can accurately track the CD tracks, is the three-beam method, the push The pull method etc. are known.

This push-pull method divides the beam for tracking into two, and accurately guides the laser pickup onto the track while comparing the amount of reflected light from each section irradiated by each beam. Such tracking is not limited to optical information recording media that have already been recorded.

Even an unrecorded optical information recording medium can be used.

In the CI) standard, such push-pull 1α is defined as (II
−12)/10. However, To is the intensity of reflected light,
11 and I2 are the intensities of the left and right reflected lights, respectively.

The current CD standard already defines the push-pull value in the recorded state, and according to this CD standard, the push-pull value must be 0.04 to 0.07 as described above.

However, when recording a playback signal conforming to the CD standard in a write-once manner, push-pull is also required when recording as described above. It is desirable that the push-pull before and after recording be as close as possible.

However, for conventional optical information recording media in which a light absorption layer containing a dye is provided on a substrate with pregrooves formed thereon, and a light reflection layer is further provided on this light absorption layer, the above-mentioned push-pull standards are not met. Of course, there is nothing that indicates the optimum conditions for the substrate and light absorption layer to satisfy the various conditions according to the above-mentioned CD standard.

The present invention has been made in view of the above-mentioned problems, and provides an optical information recording medium and optical information recording medium that can easily obtain reproduction signals specified in the CD standard. LIN provides a method for recording optical information on an optical information recording medium.

Specifically, the first objective is to provide an optical information recording medium that allows stable tracking during recording and whose push-pull signal satisfies the CD standard during playback.

A second object is to provide an optical information recording medium whose reflectance and modulation degree satisfy the CD standard during reproduction.

Thirdly, it is an object of the present invention to provide a method for recording optical information on an optical information recording medium to achieve the above-mentioned problems.

[Means for Solving the Problems] That is, the first invention provides a substrate having translucency and having pregrooves formed therein, a light absorption layer provided on the substrate and made of a dye, and this light absorption layer. 1. An optical information recording medium having a light reflecting layer formed of a metal film and provided thereon, the layer boundary between the light distribution absorbing layer and the substrate "in the land portions located on the left and right sides of the pregroove described in 1." , the depth to the bottom of the layer boundary in the pregroove portion is defined as dsul), and the layer boundary between the light absorption layer and the light reflection layer in the land portion is defined as the depth to the bottom of the layer boundary in the pregroove portion. The depth of the bottom of the layer boundary is dabs, and the real part of the complex refractive index of the L substrate is r+
sub, and the real part of the complex refractive index of the light absorption layer is rl.
abs, and the wavelength of the reproduction light is λ, and the optical phase difference between the pregroove portion and the land portion of the reproduction light reflected by the light reflection layer is Δ5=
2dsub {nsub-r+abs (1-d ab
s/d 5ub) ) /λ, and further, if the film thickness of the light absorption layer at the land portion is dln, -0.4≦△S≦-0,04, and 90nm: 5
The optical information recording medium is characterized in that idln≦350 nm.

Note that the average thickness of the light absorption layer is dav, and p = n
When abs-dav/λ, 0.05≦ρ≦1.6
It is desirable to do so.

Furthermore, the imaginary part of the complex refractive index of the light absorption layer is k abs
It is desirable that k abs≦0.3.

Further, the second invention provides a substrate having translucency and having pregrooves formed therein, a light absorption layer provided on the substrate and made of a dye, and a light absorption layer provided on the light absorption layer and made of a metal film. An optical information recording method for an optical information recording medium, characterized in that recording is performed by irradiating recording light from the substrate side using an optical information recording medium having a light reflective layer, the method according to the first invention described above. A method for recording optical information on an optical information recording medium, characterized in that bits are formed on the lands of the optical information recording medium using an optical information recording medium according to the present invention, that is, when the phase difference ΔS is negative. .

Note that it is desirable to form the bits by deforming the light absorption layer side of the substrate by irradiating recording light from the substrate side.

Next, the present invention will be explained in more detail based on FIGS. 1 to 9.

FIG. 1 is a partially cutaway perspective view of an optical information recording medium 1 according to the present invention, FIG. 2 is a vertical cross-sectional view of a main part of the optical information recording medium 1 before recording, and FIG. 3 is a longitudinal sectional view of the optical information recording medium 1 before recording. FIG. 1 is a vertical cross-sectional view of a main part after recording No. 1;

This optical information recording medium l includes a transparent substrate 2, and this substrate 2.
It has a light absorption layer 3 formed above, a light reflection layer 4 formed on this light absorption layer 3, and a protective layer 5 formed on this light reflection layer N4. Note that, if necessary, an intermediate layer (not shown) may be provided between the substrate 2 and the light absorption layer 3 and between the light absorption layer 3 and the light reflection layer 1w4.

A pregroove 6 is formed in the substrate 2 in a spiral shape. A portion other than the pregroove 6, that is, a land 7 is located on the left and right sides of the pregroove 6.

Note that the substrate 2 and the light absorbing rgI 3 are in contact with each other via the first layer boundary 8. The light absorption layer 3 and the light reflection layer 4 are in contact with each other through a second layer boundary 9. The light reflecting layer 4 and the protective layer 5 are in contact with each other through a third layer boundary 10.

As shown in FIG. 3, when the optical information recording medium 1 is irradiated with the recording light (recording laser light) LL, the light absorption layer 3 absorbs the energy of the laser light L1 and generates heat, and the substrate 2 A bit 11 is formed by thermal deformation on the side. In some cases, optical changes may occur in the light absorption layer 3.

In particular, as shown in FIG. 2, the depth from the first layer boundary 8 in the land 7 portions located on the left and right sides of the pregroove 6 to the bottom of the first layer boundary 8 in the pregroove 6 portion. Let d sub be.

The depth from the second layer boundary 9 in the land 7 portion to the bottom of the second layer boundary 9 in the pregroove 6 portion is defined as d abs.

The real part of the complex refractive index of the substrate 2, that is, the real part of the complex refractive index of the layer located on the substrate 2 side from the first layer boundary 8 (when there are multiple layers including the substrate 2, the real part of the complex refractive index of each layer The real part of the synthesized complex refractive index) is defined as n sub.

Let nabs be the real part of the complex refractive index of the light absorption layer 3.

Let dav be the average film thickness of light absorption M3. Note that the average film thickness dav here is expressed by (volume of light absorbing FJ3)/(area of region in which light absorbing layer 3 is formed).

The film thickness at the pregroove 6 portion of light absorption N3 is dg
Let it be r.

Let din be the film thickness of the light absorption lW3 at the land 7 portion.

Let kabs be the imaginary part of the complex refractive index of the light absorption layer 3.

Further, it is assumed that λ is the wavelength of the reproduction light (laser light for reproduction) L2.

Further, the optical phase difference between the pregroove 6 portion and the land 7 portion of the reproduction light L2 irradiated from the substrate 2 side and reflected by the light reflection layer 4 is assumed to be ΔS. below,
This optical phase difference ΔS will be described.

First, when light is irradiated from the substrate 2 side, up to the second layer boundary 9 in the land 7 portion when the first layer boundary 8 on the substrate 2 side of the light absorption rgI3 in the pregroove 6 is taken as a reference. The optical distance of is represented by n5ub1dsub+nabs0din.

Furthermore, the optical distance from the first layer boundary 8 on the substrate 2 side of the light absorption layer 3 in the pregroove 6 to the second layer boundary 9 in the pregroove 6 is expressed by nabsodgr. be done.

Therefore, if the optical distance difference is ND, then ND= {nsubedsub+nabs・dln)−
nabsψdzr =nsub-dsub-nabs (dgr-din)
It is.

At this time, d gr + d abs = d ln + d sub, that is, d gr - d ln = d sub - d abs. Therefore, ND= n5ub・dsub − nabs (dsub
-dabs).

Therefore, when the reproduction light L2 is irradiated from the substrate 2 side,
Optical phase difference ΔS of the reproduction destination L2 between the pregroove 6 portion and the land 7 portion reflected by the light reflection layer 4 =
2 ND/λ is 2 dsub {nsub −na
bs (1-d abs/ d 5ub) }/λ.

As shown in Fig. 4, when ΔS is changed within the range of -0.5≦ΔS≦0.5, the reflected light changes to ΔS due to the interference effect.
It is maximum at =O and minimum at ΔS=±0.5.

From the results of experiments and simulations, the present inventors have found that it is possible to obtain a reproduced signal that complies with the CD standard within the range of ΔS≦0.3.

Note that from the viewpoint of manufacturing requirements, ie, uniformity of the coating film and formability of the substrate 2, it is desirable that -0.4≦△S≦0.3.

Here, in particular, the tracking error signal, ie, the push-pull signal, depends on this optical phase difference ΔS.

For example, when ΔS is a positive number (ΔS>0), the optical distance of the land 7 portion is longer than that of the pregroove 6.

In a recording method that involves deformation of the substrate 2 at the first layer boundary 8 between the substrate 2 and the light absorption layer 3, this substrate 2
As the surface of the layer on the substrate 2 side of the light absorbing rW3 is deformed due to the deformation, the optical distance of the recording portion corresponding to the pit 11 becomes shorter. Therefore, as shown in FIG. 5, when the optical distance, that is, the amount of change ΔLd in the product of the refractive index and the optical path length, is λ/4 (the optical path difference is λ/2), the recording part and Although the push-pull difference (the amount of change in push-pull Δp, p, ) with the unrecorded portion disappears, if the amount of change ΔLd is less than λ/4, the push-pull in the recorded portion becomes large.

In this case, if recording is performed in the pregroove 6, the push-pull during recording is always positive as shown in FIG. 6, that is, the phase does not reverse, and sufficient tracking becomes possible.

Therefore, in the case of ΔS>0, it is desirable to record in the pregroove 6. By doing this, the fluctuation of the push-pull signal between the focused part and the non-bit part is small, and there is no reversal of the phase of the push-pull between the bit 11 part and the non-pit part, making it stable. can be recorded and played back.

Note that when recording is performed on land 7 in the case of ΔS>O, there is a possibility that the push-pull level becomes O during recording, as shown in FIG. When the push-pull level becomes O, tracking during recording becomes unstable, which tends to cause track jumps and jitter in recorded bits.

As a result of study, the present inventors determined that the optical phase difference ΔS is
It has been found that by setting the value in the range of 0.03 to 0.3, it is possible to provide the optical information recording medium 1 that allows stable tracking on the pregroove 6. △S is 0
．． If it is smaller than 03, the push-pull signal at the recording section is too small, making stable tracking difficult.

Furthermore, if ΔS is larger than 0.3, the reflectance in the recording portion becomes small, making it difficult to satisfy the reflectance of 70% or more stipulated in the CD standard.

Next, when ΔS<0, the optical distance of the pregroove 6 portion is longer than that of the land 7 portion.

As described above in the case of ΔS>O, in a recording method that involves deformation of the substrate 2 at the first layer boundary 8 between the substrate 2 and the light absorption layer 3, the deformation of the substrate 2 causes Since the surface of the counterfeit light absorption layer 3 on the substrate 2 side is deformed, the optical distance of the recording portion corresponding to the bit 11 is shortened. Therefore, as shown in FIG. 5, when the amount of change ΔLd in the optical distance is λ/4 (the optical path difference is λ/2),
The push-pull difference between the recorded part and the unrecorded part (push-pull change amount △p, p, > disappears, but the change amount ΔL
When d is less than λ/4, the push-pull of the recording section becomes large.

In this case, if recording is performed on the land 7, the push-pull during recording is always positive as shown in FIG. 6, that is, the phase is not reversed, and sufficient tracking becomes possible.

Therefore, in the case of ΔS×O, it is desirable to record on land 7. By doing this, stable recording is possible with small fluctuations in the push-pull signal between the bit part and the non-pit part, and no phase reversal between the bit 11 part and the non-pit part. and can be played.

Note that when recording is performed in the pregroove 6 portion in the case of ΔS<O, there is a possibility that the push-pull level becomes O at the time of recording, as shown in FIG. When the push-pull level becomes O, tracking during recording becomes unstable, which tends to cause track jumps and jitter in recorded bits.

As a result of study, the present inventors determined that the optical phase difference ΔS is
It has been found that by setting the value in the range of -0.04 to -0.4, it is possible to provide an optical information recording medium 1 capable of stable tracking. When ΔS is larger than −0.04, the push-pull signal at the recording section is too small, making stable tracking difficult. Also, this Δ
If S is smaller than -0.4, the reflectance in the recording section will be small, so the reflectance 7 specified in the CD standard will be reduced.
It is difficult to satisfy 0% or more.

Next, the depth dsub in the pregroove 6 will be explained.

This d sub is 40 nm or more, more preferably 60 nm or more.
By setting the thickness to be at least nm, it is possible to obtain an optical information recording medium 1 that has a large modulation degree, has little waveform distortion and jitter, and is capable of outputting a reproduction signal compliant with the CD standard.

Next, the film thickness dgr in the pregroove 6 portion will be explained.

When the optical phase difference ΔS>O and recording is performed in the pregroove 6, good recording with less waveform distortion and jitter can be achieved when the film thickness dgr in the pregroove 6 portion is 90 to 350 nm. It can be carried out.

In particular, when dgr is 150 to 300 nm,
The degree of modulation is also large, before and after recording.

Optimal recording can be performed with almost no push-pull changes. If d(r is smaller than 90 nm, the optical phase difference before and after recording or between the recorded part and the unrecorded part is too small, so sufficient modulation cannot be obtained. Also, if dgr is 350 nm) If it is larger than this, jitter and waveform distortion will increase, and the block error rate (BLER) will no longer satisfy the CD standard.

Next, the film thickness din at the land 7 portion will be explained.

When the optical phase difference ΔS is 0 and recording is performed on the land 7, the film thickness din at the land 7 portion is 90~90.
Good recording can be performed at 350 nm with less waveform distortion and less jitter.

In particular, when the wavelength is 180 to 350 nm, the degree of modulation is large, before and after recording. Optimal recording can be performed with almost no push-pull changes. When dln is smaller than 90 nm, sufficient modulation cannot be obtained because the optical phase difference before and after recording or between a recorded portion and an unrecorded portion is too small. Also, din
If the wavelength is larger than 350 nm, jitter and waveform distortion will increase, resulting in block error (
BLER) will no longer be able to satisfy the CD standard.

Next, optical parameters defined by ρ=nabs-dav/λ will be explained.

From the results of experiments and simulations conducted by the present inventors, it has been noted that ρ=nabs-dav/λ is a very important parameter. In other words, in the optical information recording medium 1 having a structure in which a light absorption layer 3 and a light reflection layer 4 are provided on a substrate 2, the reflectance specified in the CD standard is 70% or more and the modulation degree is I 11/I shown
top is 60% or more, and modulation depth I 3 / I t
In order to obtain an output signal with an op of 0.3 to 0.7,
Sakiboard Lll! The real part nabs of the complex refractive index of M3, the film thickness dgr of the pregroove 6 part, and the film thickness c of the land 7 part
The average film thickness with lln or its average film thickness dav,
p = nabs-dav given by the wavelength λ of the reproduction light
By setting /λ within the range of 0.05≦ρ≦1.6, the reflectance can be easily reduced to 70%, which meets the CD standard.
It is known that it is possible to do more than that.

If ρ is smaller than 0.05, the thickness dav of the light absorption layer 3 must be 0.05 μm or less, which is not practical in terms of manufacturing.

Therefore, 0.05≦ρ≦0. In the range of 6, 0.30≦ρ≦0. The range of 6 is practical, and in order to obtain a sufficient modulation depth, the range of 0.6 is practical. A range of 1 or more is desirable, and in order to obtain stable recording characteristics with a large degree of modulation, the range is 0.
．． It can be said that the range of 45±0.1 is the most desirable range.

Furthermore, as shown in Figure 8, even if ρ is in the range of 0.6 or more, if it is at the peak point on the graph, the reflectance will be 70.
It is possible to exceed %.

In the range of 0.6<ρ<1.6, there are two peak points, always in the range of 0.6<ρ<1.10 and 1.10<
ρ<1.6, and it is known that high reflectance can be obtained at these peak points.

When ρ>1.6, the film thickness becomes thick, making it difficult to control the film thickness, which is not practical in terms of manufacturing.

The graph showing the relationship between this ρ and reflectance is an exponential function,
It is expressed as a function combined with a periodic function, and as ρ increases, the amplitude of the periodic function increases.

The amplitude of such a periodic function changes using parameters such as the complex refractive index, film thickness, and homogeneity of the layers constituting the optical information recording medium 1. For example, if the refractive index of the layer on the side where light enters from the light absorption layer 3 is small, the reflectance as a whole shifts in the direction of increasing the reflectance.

Also, this graph shows the imaginary part ka of the complex refractive index of the light absorption layer 3.
It is also known that it is expressed by an exponential function with bs and dav as parameters, and as shown in FIG. 9, the larger k abs becomes, the greater the attenuation of reflectance across the graph becomes.

The light absorption layer 3 is homogeneous, and the real part of its complex refractive index nab
The inventors' simulations have shown that unless there is an uneven distribution in s and gfidav, there is no change in the period of the peak points in the above graph.

Note that depending on the conditions, it is possible to increase the reflectance at the bottom point of the graph in FIG. 8 by controlling the above parameter conditions, but if ρ is set near the bottom point, It is difficult to obtain a large degree of modulation, and in some cases, the reflectance may increase compared to before recording. Therefore, it is desirable to set ρ near the peak point.

The above k abs will also be mentioned.

In order to obtain a high reflectance, it is necessary that this kabs be 0.3 or less.

Note that the present inventors have discovered that the numerical setting of k abs is an important parameter. In other words, this k
If abs is 0.3 or less, the reflectance improves as it approaches 0. Therefore, this range is the most desirable.

However, the closer it gets to 0, the worse the recording sensitivity becomes, so it needs to be larger than 0.

Specifically, a range of 0.01 or more is desirable, and actually around 0.05 is desirable.

When ρ is in the range of 0.05 to 0.6, the imaginary part k abs of the complex refractive index of the same layer is 0. It is desirable that it is 3 or less. Moreover, in the range of ρ from 0.6 to 1.6, k
abs is 0. It is desirable that it is 2 or less.

Note that the content of the present invention is applicable even when there are other layers. For example, if a transparent /w (for example, an enhancement layer such as 5i02, an undercoat layer, etc.) is provided between the substrate 2 and the light absorption layer 3, this layer may be treated as a part of the substrate 2, When a layer (for example, an adhesive layer, a hard layer, etc.) is provided between the light absorption layer 3 and the light reflection layer 14, these layers are considered as the second light absorption layer 3, and ρ=(nl・
d1+n2・nl}/λ, and in the case of multiple layers, ρ=Σ(ni-di}/λ (where, i is an integer, ni is the real part of the complex refractive index of each layer, and di is the average of each layer. (film thickness), it can be handled in the same way even if there are multiple layers.

In addition, the composite complex refractive index expressed as the average of kabs can be calculated as K = Σdi-ki/Σdi (where ki is the imaginary part of the complex refractive index of each layer) and can be treated in the same way as for a single layer. can.

Next, the materials and physical properties of each layer will be explained.

First, the transparent substrate 2 is made of a highly transparent material with a refractive index in the range of 1.4 to 1.6 with respect to laser light, and is mainly made of resin with excellent impact resistance, such as a glass plate, Use acrylic board, epoxy board, etc. Also,
The substrate 2 may be coated with other layers, such as a solvent-resistant layer such as Si2 or an enhancement layer.

These materials are molded by means such as injection molding. The thickness of the substrate 2 is 1.1 to comply with the CD standard.
mm to 1.5 mm is desirable.

Note that, in order to fully obtain the effects of the present invention, the material of the substrate 2 is desirably polycarbonate. Further, the value of the thermal expansion coefficient α of the substrate 2 is 5.0X10-5 to 7. OX10
-'(cm/'C) is desirable.

A tracking guide means is provided on the surface of the substrate 2 on the light absorption layer 3 side. This tracking guide means may be address pits formed at predetermined intervals, so-called sample servo, or a pre-groove 6 formed in a spiral shape (tlTZ diagram, Figure 3).
Figure) is desirable.

The spiral pregroove 6 is used to guide tracking when recording a data signal.

The depth of the pre-groove 6 may be any depth as long as it satisfies normally considered conditions, but may be 30 to 250 nm.
A depth of 60 to 18 is preferable, more preferably 60 to 18
A depth of Q n rn is desirable. Also, the width of PriGlue Pro is 0. A thickness of 3 to 1.3 μm is desirable.

The distance between the pregrooves 6, the so-called tracking pitch, is preferably 1.6 μm.

Further, the tracking means such as the pregroove 6 includes time code information (ATIP: Absolute Tim).
e In Pregroove) to Pregroove 6
You can also put it in the edge of

These pregrooves 6 are usually formed by pressing a stamper during injection molding of the substrate 2, but they can also be formed by laser cutting or the 2P method (Photo-Polymer method). good.

Next, the light absorbing layer 3 is a fake layer made of a light absorbing material formed on the tracking guide means of the substrate 2, and is a layer that generates heat, melts, sublimates, deforms, or denatures when irradiated with a laser. It is. This light absorption #3
For example, it is formed by uniformly coating the surface of the substrate 2 with a cyanine dye or the like dissolved in a solvent using a spin coating method or the like.

As long as the material used for the light absorption layer 3 is a known optical recording material, it is possible to obtain the effects of the present invention, but a light-absorbing organic dye is preferable. Specifically, polymethine dyes, triarylmethane dyes, biryllium dyes, phenanthrene dyes, tetradehydrocholine dyes, triarylamine dyes, squarylium dyes, croconic methine dyes, merocyanine dyes, etc. Examples include light-absorbing organic dyes, but the invention is not limited thereto, and the effects of the present invention can be obtained as long as the material is a known optical recording material.

Note that the light-absorbing NI3 may contain other dyes, resins (for example, thermoplastic resins such as nitrocellulose, thermoplastic elastomers), liquid rubber, and the like.

Specifically, isobutylene, maleic anhydride copolymer,
Ethylene vinegar picopolymer chlorinated polypropylene, polyethylene oxide, polyamide, nylon, coumaron resin, ketone resin, vinyl acetate, polystyrene, PVA
(polyvinyl alcohol), PVE (polyvinyl ester), and the like.

As cellulose derivatives, carboxymethyl cellulose, nitrocellulose, HI'C (hydroxypropyl cellulose), HEC (hydroxyethyl cellulose)
, MC (methyl cellulose), EC (ethyl cellulose), EHEC (ethyl hydroxyethyl cellulose),
Examples include CMEC (carboxymethylethylcellulose).

Examples of the oligomer include oligostyrene and methylstyrene oligomer.

Examples of the elastomer rubber include styrene block copolymers, urethane thermoplastic elastomers, and the like.

The light absorption layer 3 is made by dissolving the above dye and any additives using a known organic solvent (for example, ketone alcohol, acetylacetone, methylcellosolve, toluene, etc.) and adding it to the substrate 2 on which pregrooves 6 are formed. the upper surface,
Alternatively, further layers on the substrate 2 may be formed on the coated surface.

Formation methods in this case include vapor deposition, LB method, or spin code method, but the thickness of one layer can be controlled by adjusting the concentration, viscosity, drying speed of the solvent, etc. of the light absorption layer 3. A spin code method that allows for

Specifically, the thickness of the light absorption layer 3 can be adjusted by changing the rotation speed of the spin code, by performing spin code by mixing substances with different viscosities, and by using multiple types of solvents for dissolution. Examples include a method of performing spin coding using a light-absorbing substance that has been mixed with a high boiling point substance, or a method of performing spin coding using a high boiling point substance.

Next, the light reflecting layer 4 is a metal film, and is formed of, for example, gold, silver, copper, aluminum, or an alloy containing these by means such as vapor deposition or sputtering.

Since it is necessary to have a reflectance of 70% or more, a metal film mainly composed of gold or an alloy containing gold is desirable among these.

In addition, in order to prevent oxidation of the light reflection layer 4, the light reflection layer 4 is
Other layers such as an oxidation-resistant layer may be provided on top of 4.

Next, the insulating layer 5 is formed of a resin having excellent impact resistance similar to that of the substrate 2. For example, it is formed by applying an ultraviolet curable resin by a spin code method and curing it by irradiating it with ultraviolet rays. In addition, epoxy resin, acrylic resin, silicone hard coat resin, etc. may also be used.

The protective layer 5 can generally be obtained by applying a monomer or oligomer of an organic compound that can be polymerized to become a polymer, and then subjecting it to a crosslinking reaction. However, the material is not limited to organic compounds, and inorganic materials may be formed by known means such as sputtering or vapor deposition.

In addition, when obtaining this as an organic polymer by crosslinking reaction, from the viewpoint of workability, a mixture of monomers and oligomers of organic heavy compounds having one or more reactive acryloyl groups (-CH=CiI2) in the molecule is used to initiate the reaction. An advantageous method is to add a small amount of a reaction agent or a reaction catalyst, apply a liquid mixture of these, and irradiate it with ultraviolet rays or electron beams to effect crosslinking.

However, the crosslinking method is not limited to this; crosslinking may proceed with heat, such as with epoxy or urethane, or with air, such as with dialkoxysilane coupling agents. The polymerization reaction may proceed with the moisture contained therein.

The main chain and side chain of the crosslinked product thus obtained may be a saturated or unsaturated linear hydrocarbon, or may contain a cyclic compound such as melamine or bisphenol. In addition, polyethers containing one or more ether bonds in the main chain or side chain of this crosslinked product, polyesters containing ester bonds, polyurethanes containing urethane bonds, iomers containing ionic bonds, polyamides containing amide bonds, and imide bonds. Other bonds may be included, such as polyimide containing sulfone bonds, polysulfone containing sulfone bonds, polysulfide containing sulfide bonds, and the like. It may be a copolymer compound containing two or more of these bonds, or it may be a block polymer.

Further, in order to improve the moisture resistance of these crosslinked products, a fluorocarbon or the like may be included in the side chain, and an epoxy resin may be included in order to prevent deterioration due to hydrogen halide.

In addition, in order to improve the adhesion with the light reflective layer 4, the side chain may contain a hydroxyl group, a carboxyl group, an acrylic group, an amino group, a vinyl acetate group, etc., or a main chain or a side chain may contain a base. May contain acid.

When forming the protective layer 5, in addition to tM resin, its reactant, reaction initiator, etc. during coating, in order to improve coating properties,
A solvent and a diluent may be included. Further, in order to stabilize the coating film, a leveling agent, a plasticizer, an antioxidant, an antistatic agent, etc. may be included. Further, if necessary, it may be colored with a pigment or dye.

The curing of the resin can be changed depending on the crosslinking density of the crosslinked structure or the concentration of reactive acroyl, and it also changes depending on the degree of freedom of molecular rotation of the oligomer itself, which can become the main chain.

Furthermore, in the optical information recording medium 1 according to the present invention, layers behind the light absorption layer 3 with respect to the substrate 2, such as light reflection 7W4 and protection iI! /W5 etc. are desirably made of a material having a higher thermal deformation temperature and higher hardness than the counterfeit material on which the bit 11 is formed. Forming the rear layer using a layer with high hardness is effective in reducing the block error rate of recording signals specified in the CD standard.

Within the usage environment temperature specified in the CD standard, that is, -15
In the temperature range from ℃ to 70℃, by setting the hardness of the protective layer 5 to 2 parts or more in terms of pencil hardness, deformation of the second layer boundary 9 on the light reflection y#4 side of the light absorption 13 can be suppressed to a small value. I can do it. As a result, waveform distortion can be suppressed, and B
Good recording with small LER can be performed. As the hardness of the protective layer 5 decreases, the BLER tends to increase.

The thermal expansion coefficient α of the protection rgI5 is set as the operating environment temperature −1
Within the range of 5°C to 70°C, 1.5 x 10-5 to
By keeping it within the range of 9.0XIO-5, this protection 1
Since the layer 5 exhibits the same thermal volume change as the substrate 2, the optical information recording medium 1 as a whole is less likely to warp even when heat is applied.

α is 1. In the case of 5x, to-' grooves, the substrate 2 expands more greatly due to expansion during heating, so the optical information recording medium 1 warps toward the storage PIN 5 side, and tensile force is generated in each layer of the substrate 2, causing the recording This causes jitter in the pit 11 to increase.

If α is larger than 9.0
#5 sag, causing delamination between the light absorbing layer NI3 and the light reflecting layer N4 and between the light reflecting layer 4 and the protective layer 5.

In addition, by setting the shrinkage rate of Protective 11j #5 to 12% or less, no cracks will occur in the protective layer 5 even when a heat cycle test is performed so that no distortion of the resin remains after it is cured. . Considering mechanical strength, this shrinkage rate is desirably 10% or less.

Additionally, a light reflective layer 4 is provided between the light reflective layer 4 and the protective layer 5.
An oxidation-resistant layer can also be interposed to prevent oxidation.

[Function] Recording can be performed on the optical information recording medium according to the present invention using a known optical information recording device. An overview is given below. That is, the optical information recording medium 1 is arranged so that the surface of the transparent substrate 2 faces the side on which the laser irradiation means, that is, the pickup of the optical information recording apparatus is provided. This optical information recording medium 1
While being rotated by a spindle motor, a laser spot modulated into a signal compliant with the CD standard is tracked by the tracking guide means, and the optical information recording medium 1 is tracked by a pickup.
By irradiating w3, pits 11 are formed.

In the optical information recording method according to the present invention, the wavelength λ is 78
It is desirable to irradiate with a laser spot around 0 nm. Also, in relation to the CD standard, the linear velocity is 1.2~
It needs to be 1.4m/sec, and the recording power is 6~
Approximately 9 mW is sufficient.

That is, recording can be performed in a commercially available CD player by increasing its recording power to a level greater than that used during playback.

Note that during this recording, if the land 7 portion between the pregrooves 6 is optically bright due to conditions such as the film thickness of the light absorption layer 3 as described above, the laser is irradiated into the pregroove 6 to form the pit 11. It is desirable to form

Conversely, when the pregroove 6 is optically bright, it is desirable to form the pit 11 in the land 7 portion.

By forming the pits 11 under these conditions, the difference in brightness of the reflected light of the reproduction laser during reproduction becomes clear, and a high degree of modulation can be obtained.

In this way, it is possible to easily create an optical information recording medium 1 that can obtain a reproduced signal that satisfies the CD standard.

Note that in the optical information recording medium 1 according to the present invention, as shown in FIG. 3, a recording laser beam L1 is applied to the light absorption layer 3 from the substrate 2 side.
When irradiated with the laser beam L1, the light absorption layer 3 absorbs the laser beam L1 and generates heat, and the surface of the substrate 2 is locally deformed, so that bits 11 are preferably formed on the surface of the substrate 2.

Alternatively, the light absorption layer 3 may undergo an optical change, thereby forming the bit 11.

Furthermore, the components melted and decomposed by the irradiation with the laser beam L1 diffuse into the softened substrate 2, partially mix and combine with the components forming the substrate 2, and the light absorption N3
The bit 11 may also be formed by producing a portion optically different from other portions of the substrate 2.

The recorded signal is reproduced using a reproduction laser beam L2 from the substrate 2 side.
This is done by reading the difference in brightness of the optical phase difference ΔS between the reflected light at the focus 11 part and the reflected light at parts other than the bit 11.

Further, in the present invention, in addition to the optical information recording medium 1 in which the light absorption layer 3 is formed on almost the entire surface of the substrate 2, a part of the substrate 2 is a recordable area having the light absorption layer 3, and the other part is a CD.
RO whose format signal has reproducible bit 11
It is also applicable to optical information recording media in the M area. Such an optical information recording medium is, for example, RO on the surface of the substrate 2.
Bits for signal reproduction are previously formed in the M area using a stamper or the like, and light absorbing Nj3 is formed only in the storable area outside of the bit.

In such optical information recording media, a large amount of uniform data can be recorded in advance in the ROM area by pressing, etc., and since there is no optical absorption /w3, it can be easily erased by mistake, or if other data is There is no risk of erroneous recording. Further, in the area having the light absorption layer 3, user's own data can be arbitrarily recorded. Since this recorded data can be reproduced with a signal conforming to the CD standard, it can be reproduced by a commercially available CIT player in the same way as the information in the ROM area.

[Example] Next, examples of the optical information recording medium and the method of recording optical information on the optical information recording medium according to the present invention will be described below. Note that Examples 1 and 2 illustrate the case where the optical phase difference ΔS between the unrecorded pregroove 6 and the land 7 is positive, and Examples 3 and 4 illustrate the case where ΔS is negative. There is.

(Example 1) @0.5μm, depth 1100n, and pinch 1.6μ
A spiral pregroove 6 with a thickness of 1.m is formed.
A polycarbonate substrate having a diameter of 2 mm, an outer diameter of 120 mm, and an inner diameter of 15 mm was molded by injection molding.

0.65 g of 1,1' dibutyl as cyanine dye3.
3. 3'3'Tetramethyl4,5゜4'
By dissolving 5'-dibenzoindodicarbocyanine perchlorate (manufactured by Nippon Kanko Shiki Co., Ltd., NK-3219) in 10 ml of diacetone alcohol, and spin-coding it onto the above substrate while changing the rotation speed appropriately. A light absorption layer having an average thickness dav of 140 nm was formed.

Depth d abs of this light absorption layer in pregroove 6
is 49 n rn, and the complex refractive index rsabs is 2.7
Since the wavelength λ of the reproduction light is 780 nm, the optical parameter ρ at this time is 0.48.

Also, the refractive index of polycarbonate, which is the material of the substrate, n s
Since ub is 1.58, the optical phase difference ΔS between the unrecorded pregroove and the land is 0°052.

Also, from the above results, the film thickness dgr of the pregroove 6 is 1
It is 75 nm.

An Au film with a thickness of 60 nm was formed on the entire surface of this disk by vacuum evaporation. Further, an ultraviolet curable resin was spin-coded on the light reflecting layer, and was cured by irradiating ultraviolet rays to form a 10 μm thick protective TII layer.

When recording was performed on the thus obtained optical information recording medium using a semiconductor laser with a wavelength of 780 nm at a linear velocity of 1.4 m/sec,
The optimum power was 7.2 mW. EFM with this power
The signal is recorded in the pregroove section, and the optical information recording medium at that time is transferred to a commercially available CD player (Au
When the optical information recording medium was reproduced using a laser with a wavelength of 780 nm and a reproduction power of 0.5 mW, the reflectance of the optical information recording medium was 77.3%, and the modulation degree I 11 determined from the eye pattern of the reproduced signal was / I top is 0.
73, I3/1top is 0.42, block error rate is 1.6 x 10-, push-pull value is 0.067
Met.

This sufficiently meets the standards set by the CD standard.

(Comparative Example 1) Recording was performed on the land portion of the unrecorded area of the optical information recording medium prepared in Example 1 using a semiconductor laser with a wavelength of 780 nm at a linear velocity of 1.4 m/sec and an optimum recording power. When this recorded portion was reproduced in the same manner as in Example 1, the block error rate was 5.0XIO-
2. Push-pull during playback was 0.01.9. None of these satisfy the CD standard.

(Example 2) On a polycarbonate substrate molded in the same manner as in Example 1 above, 0.78 g of the same cyanine dye as in Example 1 was dissolved in 1.0 cc of diacetone alcohol solvent, and the rotation speed was adjusted to an appropriate number using a spin cord method. It was applied while changing.

The film thickness dav after film formation was 260 nm.

The depth dsub in the pregroove of this light absorption layer is 57
nm, and the complex refractive index nabs is 2.7.

The wavelength of the reproduction light is 780 nm, and the optical parameter ρ at this time is 0.90.

Further, ΔS in the unrecorded state at this time was 0.11.

The film J'Xdgr of the light absorption layer in the pregroove is 29
It becomes 0 nm.

An Au film with a thickness of 60 nm was formed on the entire surface of this disk by vacuum evaporation. Further, an ultraviolet curable resin was spin-coded on top of this light reflective layer, and was cured by irradiating ultraviolet rays to form a protective layer with a thickness of 10 μm.

The optical information recording medium thus obtained was coated with a wavelength of 7 as in Example 1.
When recording was performed using an 80 nm semiconductor laser at a linear velocity of 1°4 rn/see, the optimum recording power was 5.2 mW. The EFM signal with this power was recorded in the pregroove portion of the optical information recording medium, and the recorded portion was reproduced in the same manner as in Example 1.

Reflectance is 73.2%, I 11/I sio of reproduced signal
p is 0°85, I3/I top is 0.45, and block error rate is 2. The 2xto-3 push-pull value was 0.053. This fully satisfies the standards set by the CD standard.

(Comparative Example 2) Recording was performed on the land portion of the unrecorded area of the optical information recording medium prepared in Example 2 using a semiconductor laser with a wavelength of 780 nm at a linear velocity of 1.4 m/sec and an optimum recording power. When this recorded portion was reproduced in the same manner as in Example 1, the block error rate was 7.8X10-
2 Push-pull during playback was 0.022. None of these satisfy the CD standard.

(Example 3) Radiation 0.1 pm, depth 100 nm, and pitch 1.
Thickness 1 with 6μm spiral pregroove formed
．． A polycarbonate substrate having a diameter of 2 nm, an outer diameter of 120 mm, and an inner diameter of 15 mm was molded by injection molding.

0.70 g of 1,1' dibutyl as cyanine dye3.
3. 3'3'tetramethyl4,5゜4'
5'-dibenzoindodicarbocyanine perchlorate (manufactured by Nippon Kanko Shiki Co., Ltd., NK-3219) was dissolved in 10 ml of diacetone alcohol, and placed on the above substrate with a spin code while changing the rotation speed appropriately. By doing so, a light absorption layer having an average thickness dav of 210 nm was formed.

The depth d abs in the pregroove of this light absorption layer is 12
nm, the complex refractive index n abs is 2.7, and the wavelength λ of the reproduction light is 780 nm, so the optical parameter ρ at this time is 0.73.

In addition, the refractive index n of polycarbonate, which is the material of the substrate
Since sub is 1.58, the optical phase difference ΔS between the unrecorded pregroove and the land is −0.20.

Also, from the above results, the film thickness din at the land is 172n
It is m.

An Au film with a thickness of 60 nm was formed on the entire surface of this disk by vacuum evaporation. Further, an ultraviolet curable resin was spin-coded on this light reflective layer, and was cured by irradiating ultraviolet rays to form a 10 μm thick adhesive #IN.

When recording was performed on the thus obtained optical information recording medium using a semiconductor laser with a wavelength of 780 nm at a linear velocity of 1.4 m/sec,
The optimum power was 6.5rnW. EF with this power
The M signal was recorded on the land. At that time, the reflectance of the optical information recording medium is 74.5%, the value obtained from the eye pattern of the reproduced signal is 11/I t, op is 0.82, and I 3
/ I top is 0.42, block error rate is 1
．． The 8X10 push-pull value was 0.048.

This fully satisfies the standards set by the CD standard.

(Comparative Example 3) Recording was performed on the pregroove portion of the unrecorded area of the optical information recording medium prepared in Example 3 using a semiconductor laser with a wavelength of 780 nm at a linear velocity of 1.4 m/sec and an optimum recording power. When this recorded portion was reproduced in the same manner as in Example 3, the block error rate was 8.5.
X10-' The push-pull during playback was 0.009. None of these satisfy the CD standard.

(Example 4) On a polycarbonate substrate molded in the same manner as in Example 3 above, 0.85 g of the same cyanine dye as in Example 3 was dissolved in 10 cc of diacetone alcohol solvent, and the rotation speed was changed appropriately using the spin cord method. I applied it while letting it work. The film J-Idav after film formation was 240 nm.

The depth d sub in the pregroove of this light absorption layer is 10
nm, and the complex refractive index n abs is 2.7.

The wavelength of the reproduction light is 780 nm, and the optical parameter ρ at this time is 0.83. Further, ΔS in the unrecorded state at this time was −0.22.

Further, the film thickness d1n of the light absorption layer on the land at this time is 201 nm.

An Au film with a thickness of 60 nm was formed on the entire surface of this disk by vacuum evaporation. Further, an ultraviolet curable resin was spin-coded on top of this light reflective layer, and was cured by irradiating ultraviolet rays to form a protective layer with a thickness of 10 μm.

When recording was performed on the optical information recording medium thus obtained using a semiconductor laser having a wavelength of 780 nm at a linear velocity of 1°4 m/sec in the same manner as in Example 3, the optimum recording power was 6.0 mW. When the °EFM signal with this power was recorded in the pregroove section of an optical information recording medium and the recorded section was reproduced in the same manner as in Example 3, the reflectance was 72.1%, and the I 1 of the reproduced signal was
1/I top is 0°84, I3/I top is o, 42, block error rate is 1.9X10-3,
The push-pull value was 0.052. Moreover, the push-pull of the unrecorded portion was also <0.052. This is C
It fully satisfies the criteria set forth in the D standard.

(Comparative Example 4) Recording was performed on the pregroove portion of the unrecorded area of the optical information recording medium prepared in Example 4 using a semiconductor laser with a wavelength of 780 nm at a linear velocity of 1.4 m/sec and an optimum recording power. When this recorded portion was reproduced in the same manner as in Example 3, the block error rate was 8.0X.
IO-', push-pull during playback was 0.012. None of these satisfy the CD standard.

[Effects of the Invention] As described above, according to the present invention, by setting the optical retardation ΔS and the film thickness at the land portion of the light absorption layer to predetermined values, a disc that complies with the current CD standard can be obtained In particular, it is possible to provide an optical information recording medium that can satisfy the push-pull value specified in the CD standard, as well as standard values for reflectance and modulation degree, and a method for recording on this optical information recording medium.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of an optical information recording medium 1 according to the present invention. FIG. 2 is a vertical cross-sectional view of the main part for explaining the optical information recording medium 1 and the optical information recording method on this ZUM information recording medium 1, and FIG. A vertical cross-sectional view of the main part of the state, Figure 4 is a graph of the relationship between the yC phase difference ΔS and the amount of reflected light, and Figure 5 is the amount of change in optical distance ΔL before and after recording.
d and the amount of push-pull change △P before and after recording,
Figure 6 is a graph showing the change in push-pull before and after recording, and fIS7 is a graph showing the change in push-pull before and after recording. A graph showing the case where the positive and negative are reversed. Figure 8 is a graph of the relationship between p (=nabs-dav/λ) and reflectance. Figure 9 is a graph of the relationship between complex refractive index kabs of the light absorption layer 3 and reflectance. It is a graph. i, Optical information recording medium 2, Transparent substrate 3, Light absorbing layer 4, Light reflecting layer 5... Protective layer 6 , Pre-groove 7 , Land 8 , First layer boundary 9 , Second layer boundary i o , , third layer boundary 11 , , , , bit dsub , , , light absorption layer 3 in land 7 portion
From the first layer boundary 8 between the substrate 2 and the substrate 2, the depth dabs of the bottom of the first layer boundary 8 in the pregroove 6 portion, ..., the light absorption layer 3 in the land 7 portion
From the second layer boundary 9 between the light-absorbing layer 3 and the substrate 2, the bottom depth n5ub of the second layer boundary 9 in the pre-groove 6 portion is: The real part nabs of the complex refractive index of the layer located on the substrate 2 side from the layer boundary 8 of , , , the real part k of the complex refractive index of the light absorption M3
abs, , , imaginary part d of the complex refractive index of the light absorption layer 3
av, , , average film thickness dgr of light absorption layer 3 , , ,
, , Thickness d ln of the light absorption layer 3 at the pregroove 6 part , , Thickness λ of the light absorption layer 3 at the land 7 part . . . Wavelength of reproduction light

Claims (1)

[Scope of Claims] (1) A substrate having translucency and having pregrooves formed therein; A light-absorbing layer provided on the substrate and made of a dye; A light-absorbing layer provided on the light-absorbing layer and made of a metal film. an optical information recording medium having a light reflecting layer, the layer boundary between the light absorbing layer and the substrate in land portions located on the left and right sides of the pregroove to the layer boundary in the pregroove portion; dsu depth to bottom
b, the depth from the layer boundary between the light absorption layer and the light reflection layer in the land portion to the bottom of the layer boundary in the pregroove portion is dabs, and the real number of the complex refractive index of the substrate nsub is the real part of the complex refractive index of the light absorption layer, nabs is the wavelength of the reproduction light, and the pregroove part of the reproduction light reflected by the light reflection layer and the land ΔS=2dsub{nsub-nabs(1-dabs
/dsub)}/λ, and further, when the film thickness at the land portion of the light absorption layer is dln, -0.4≦ΔS≦-0.04 and 90nm≦dln≦350nm. Characteristic optical information recording media. (2) The average thickness of the light absorption layer is dav, and ρ=na
A claim characterized in that, when bs・dav/λ, 0.05≦ρ≦1.6 (
1) The optical information recording medium described above. (3) Claim (2) characterized in that kabs≦0.3, where kabs is the imaginary part of the complex refractive index of the light absorption layer.
The optical information recording medium described above. (4) A substrate that is translucent and has a pregroove formed thereon, a light absorption layer provided on this substrate and made of a dye, and a light reflection layer provided on this light absorption layer and made of a metal film. 1. An optical information recording method for an optical information recording medium, characterized in that recording is performed by irradiating recording light from the substrate side using an optical information recording medium having land portions located on the left and right sides of the pregroove. The depth from the layer boundary between the light absorption layer and the substrate in , to the bottom of the layer boundary in the pregroove portion is dsu
b, the depth from the layer boundary between the light absorption layer and the light reflection layer in the land portion to the bottom of the layer boundary in the pregroove portion is dabs, and the real number of the complex refractive index of the substrate nsub is the real part of the complex refractive index of the light absorption layer, nabs is the wavelength of the reproduction light, and the pregroove part of the reproduction light reflected by the light reflection layer and the land ΔS=2dsub{nsub-nabs(1-dabs
/dsub)}/λ, and further, when the film thickness at the land portion of the light absorption layer is dln, -0.4≦ΔS≦-0.04 and 90nm≦dln≦350nm. A method for recording optical information on an optical information recording medium, characterized in that pits are formed in the lands of the optical information recording medium. (5) The method for recording optical information on an optical information recording medium according to claim 4, characterized in that the light absorption layer side of the substrate is deformed by irradiating recording light from the substrate side.