JPH03230333A - 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, film thickness of a light-absorbing layer in a land area and depth of a pregroove. CONSTITUTION:The pregroove and light-absorbing layer are formed so as to satisfy the relations expressed by formulae II, III and IV. 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, 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 4 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] The present invention relates to an optical information recording medium and a method of recording optical information on the optical information recording medium, and particularly relates to an optical information recording medium having translucency and forming a pregroove. an optical information recording medium that is optically writable and readable and has a light-absorbing layer provided on the substrate and made of a dye, and a light-reflecting layer provided on the light-absorbing layer and made of a metal film. The present invention also relates to a method for recording optical information on this tip f[l 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.

Further, JP-A-59-135640 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 conventional write-once type optical information recording medium that uses a dye as a light absorption layer, 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 that is generally widely used for playback-only CDs.

Therefore, in order to play back a CD on a commercially available CD player, it is necessary to obtain a playback signal 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, and there must be no change in the reproduction signal. ! 1w1 width modulation degree I11/Itop is 0.
6 or more, and the modulation degree I 3 / I top of the modulation amplitude in the reproduced signal is 0. 3-0. 7, the block error rate must be 3.0XIO-2 or less, and the push-pull value when using the push-pull method for bit tracking is 0.04.
~0.07 is required.

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 can be applied not only to optical information recording media that have already been recorded, but also to optical information recording media that have not yet been recorded.

The CD standard defines these push-pull values as (II-I2
)/IO. However, IO is the intensity of reflected light,
Il and E2 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.

[Problem to be solved by the invention 51 The present invention has been made in view of the above-mentioned problems, and provides an optical information recording medium that can easily obtain a reproduction signal specified in the CD standard, and an optical information recording medium that can easily obtain a reproduction signal specified in the CD standard. An object of the present invention is to provide a method for recording optical information on a 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 111g as described above.

caig] In other words, the 51st light of No.-51 is a substrate having a translucent property and in which a pregroove is formed, a pre-groove layer provided on this substrate and made of a dye, and a layer that is made of a dye, and An optical information recording medium having a light reflection layer provided on an absorption layer and made of a metal film, wherein from the layer boundary between the light absorption layer and the substrate in 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 light reflection layer in the land portion to the bottom of the layer boundary in the pregroove portion is defined as dsub. Let the depth of the bottom of the substrate be dabs, and the real part of the complex refractive index of the substrate be n5
ub, and the real part of the complex refractive index of the light absorption layer is n a
bs, 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 ΔS =
2 dsub (r+sub -rtabs (1-
(] abs/ d 5ub) ) /λ, and further, the film 1 da in the land portion of the light absorption layer is dl
When n, -0,4≦ΔS≦-0,04,90r
t m≦den≦35 Orlm, and dsub≧4
This is an optical information recording medium characterized by being Or+m.

In addition, the average lit! of the light absorption layer mentioned above! Let the thickness be dav and p
When = nabs-d av/λ, 0.05≦
It is desirable that ρ≦1.6.

Furthermore, kab
It is desirable that kabs≦0.3, where s.

In addition, the second invention provides a substrate having translucency and a pregroove formed therein, a light absorption layer provided on this substrate and composed of a dye, and a metal film formed on the light absorption layer. An optical information recording method for an optical information recording medium, characterized in that recording is performed by irradiating an IC (recording) from the substrate side using an optical information recording medium having a light reflecting layer composed of Using the optical information recording medium according to the first invention, that is, when the phase difference ΔS is negative, bits are formed on the lands of the optical information recording medium, and the optical information recording medium is characterized in that bits are formed on the lands of the optical information recording medium. This is a recording method.

Note that it is desirable to form a double bit by irradiating recording light from the substrate side to deform the light absorption layer side of the substrate.

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 longitudinal cross-sectional view of a main part of the optical information recording medium 1 before recording, and FIG. 3 is a partial cutaway perspective view of the optical information recording medium 1 according to the present invention. FIG. 2 is a vertical cross-sectional view of a main part of the medium 1 after recording.

This optical information recording medium 1 includes a transparent substrate 2 and a transparent substrate 2.
A light absorbing layer 3 formed above, a light reflecting layer 4 formed on this light absorbing layer 3, and a protective layer 4 formed on this light reflecting layer 4.
f15. Note that an intermediate N (not shown) may be provided between the substrate 2 and the light absorption layer 3 and between the light absorption layer N3 and the light reflection layer 4, if necessary.

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 absorption layer 3 are in contact with each other through a first layer boundary 8. The light absorbing layer N3 and the light reflecting layer 4 are in contact with each other through a second layer boundary 9. The light reflecting layer 4 and the protective NI 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 recording light (recording laser light) Ll, the light absorption layer 3 absorbs the energy of this laser light L1 and generates heat, and the substrate 2 Thermal deformation occurs on the side, forming pits 11. 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 fake located on the substrate 2 side from the first layer boundary 8 (if these fakes have 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 n abs be the real part of the complex refractive index of the light absorption layer 3.

The t'Tl average film thickness of the light absorption layer 3 is set to dav. Note that the average film thickness dav here is (volume of light absorption layer 3)/(
(area of the region where the light absorption N3 is formed).

The film thickness at the pregroove 6 portion of the light absorption layer 3 is dg
Let it be r.

Let dln be the film thickness of the light absorption layer 3 at the land 7 portion.

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

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

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, the second layer boundary 9 in the land 7 portion is determined based on the first layer boundary 8 on the substrate 2 side of the light absorption layer 3 in the pregroove 6. The optical distance to is represented by n5ub-dsub+nabsΦdln.

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= {nsub-dsub+nabs-dln)-
nabso dgr =: n5ub1dsub-nabs (dzr-dln
).

At this time, dgr+dabs=dln+dsub, that is, dgr-d1n=dsub-dabs. Therefore, ND=: n5ubIIdsub −nabs (ds
ub-dabs).

Therefore, when the reproduction light L2 is irradiated from the substrate 2 side,
Optical phase difference ΔS of reproduction light 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(L-dabs/dsub)}/λ.

As shown in FIG. 4, ΔS is −0, 5≦ΔS≦0. 5
When changing within the range of Δ
It becomes maximum at S=O, and ΔS=±0. It becomes minimum at 5.

From the results of experiments and simulations, the present inventors found that ΔS≦0. It has been found that it is possible to obtain a reproduced signal that complies with the CD standard within the range of 3.

Note that from the viewpoint of manufacturing requirements, ie, uniformity of the coating film and formability of the substrate 2, -0.4≦ΔS≦0. 3 is desirable.

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>O), 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, the surface of the layer on the substrate 2 side of the light absorption layer 3 deforms as the substrate 2 deforms. Because of the deformation, the optical distance of the recording section corresponding to bit 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 The difference in push-pull (change amount of push-pull △P, P, ) between Put it away.

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, when ΔS>0, it is desirable to record in the pregroove 6. By doing this, the fluctuation of the push-pull signal between the bit part and the non-bit part of the push-pull signal is small, and there is no reversal of the push-pull phase between the bit part 11 and the non-bit part. Stable recording and playback can be performed.

Note that when recording is performed on the land 7 portion in the case of ΔS>0, 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 is likely 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
0.03~0. It has been found that by setting the range of 3, it is possible to provide an optical information recording medium 1 capable of stable tracking on the pregroove 6. When ΔS is smaller than 0.03, 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 is O, 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 layer on the substrate 2 side of the light absorption N3 is deformed, the optical distance of the recording portion corresponding to the bit 11 is shortened. Accordingly, as shown in FIG. The amount of change in pull △p, p, ) disappears, but the amount of change 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 perform recording 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-bit part, and no phase reversal between the bit 11 part and the non-bit 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
S is -0. If it is smaller than '4, the reflectance in the recording section becomes small, making it difficult to satisfy the reflectance of 70% or more stipulated in the CD standard.

Next, the depth d sub in the pregroove 6 part
I will explain about it.

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 d and r in the pregroove 6 portion will be explained.

When the optical phase difference ΔS>0 and recording is performed in the pregroove 6, good recording with less waveform distortion and jitter is performed when the film thickness dzr in the pregroove 6 portion is 90 to 350 nm. I can do it.

In particular, when the dgr is 150 to 300 nrn, the degree of modulation is large, before and after recording.

Optimal recording can be performed with almost no push-pull changes. When dgr 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. Furthermore, if dgr is greater than 350 nm, jitter and waveform distortion become large, making it impossible for block error rays (BI, ER) to satisfy the CD standard.

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

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

In particular, when the wavelength is 80 to 350 nm, the degree of modulation is large, and 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, dln
When B is larger than 350 nm, jitter and waveform distortion become large, and the block error rate (B
Next, the 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. That is, in the optical information recording medium 1 having a structure in which the light absorption layer N3 and the light reflection layer 4 are provided on the substrate 2, the reflectance specified in the CD standard is 7.
0% or more and I 11/ I expressed as modulation degree
top is 60% or more, and modulation depth I 3 / I to
In order to obtain an output signal with p of 0.3 to 0.7, the real part n abs of the complex refractive index of the light absorption layer 3, the film thickness dgr of the pregroove 6 part, and the film thickness dln of the land 7 part are ρ=nabs-dav/λ given by the average film thickness or the average film thickness dav and the wavelength λ of the reproduction light is 0.
It has been found that by setting the reflectance within the range of 05≦ρ≦1.6, it is possible to easily increase the reflectance to 70% or more, which conforms to the CD standard.

If the above ρ is smaller than 0.05, light absorption/W3
The film thickness dav must be considerably thinned to 0.05 μm or less, which is not practical for manufacturing.

Therefore, in the range of 0.05≦ρ≦0.6,
The range of 0.30≦ρ≦0.6 is practical, and in order to obtain a sufficient degree of modulation, the range of 0.1 or more is desirable, and in order to obtain stable recording characteristics with a large degree of modulation, 0. .45
It can be said that the range of ±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, and always in the range of 0.6<ρ<1.10. 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 with parameters such as the complex refractive index of the optical edge f[the fake constituting the recording medium 1, the film thickness, and their homogeneity. 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 k of the complex refractive index of the light absorption layer 3.
It is also known that it is expressed by an exponential function with abs and dav as parameters, and as shown in FIG. 9, as kabs becomes larger, the attenuation of the reflectance of the entire graph becomes larger.

The light absorption layer 3 is homogeneous, and the real part of its complex refractive index n a
The inventors have found through simulations that unless there is non-uniform distribution in bs and film thickness dav, there is no change in the period of the points showing the peaks 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 below.

In order to obtain high reflectance, this k abs should be 0. It must be 3 or less.

The present inventors have discovered that the numerical setting of kabs is an important parameter. That is, this k abs is 0. If it is 3 or less, the reflectance improves as it approaches 0. Therefore, this range is the most desirable. However, the closer it gets to O, the worse the recording sensitivity becomes.
It needs to be bigger.

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

The above ρ is 0.05 to 0. 6, the imaginary part k abs of the complex refractive index of the same layer is 0.6. It is desirable that it is 3 or less. Also, ρ is 0. In the range of 6 to 1.6, kabs 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 layer 1 (for example, an enhancement layer such as 5i02, a subbing 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, and the light absorption layer 3 may be treated as a part of the substrate 2. /I between absorption N3 and light reflection layer 4
When I (for example, adhesive layer, hard layer, etc.) is provided,
Considering these layers as the second light absorption layer 3, ρ=(nl
・d1+n2・n2}/λ, and when there are 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 real part of the complex refractive index of each layer. average 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 for laser light.
Items mainly made of resin that have excellent W impact resistance, such as glass plates and acrylic plates.

Use epoxy board etc. Further, the substrate 2 may be coated with another layer, 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 set to comply with the CD standard. 1mm~1
．． 5mm 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 5.0XIO-' to 7.0XIO-'
(cm/°C) is desirable.

A tracking guide means is provided on the surface of the substrate 2 on the light absorption N3 side. As this tracking guide means, address pits consisting of pits formed at predetermined intervals, so-called sample servos, may be used, but pre-grooves 6 formed in a spiral shape (Figs. 2 and 3) may be used.
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 1 m is preferred, more preferably 60 to 1 m.
A depth of 80 nm is desirable. Further, the width of the pregroove 6 is preferably 0.3 to 1.3 μm.

The distance between pregroove 6, the so-called tracking pitch, is . 6 μm is desirable.

Further, the tracking means such as the pregroove 6 includes time code information (ATIP: Absolute
Time In Pregroove) may be placed at the edge of the pregroove 6.

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). may be manufactured.

Next, the light-absorbing layer 3 is a layer made of a light-absorbing substance 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 N/
3, for example, cyanine dye etc. dissolved with a solvent,
This is formed by uniformly coating the surface of the substrate 2 by means such as a spin code method.

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 absorption 7W3 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.

Examples of cellulose derivatives include carboxymethyl cellulose, nitrocellulose, RPC (hydroxypropyl cellulose), HEC (hydroxyethyl cellulose),
MC (methylcellulose).

Examples include EC (ethylcellulose), EIIEC (ethylhydroxyethylcellulose), and 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 method, LB method, spin code method, etc., but by adjusting the concentration, viscosity, drying speed of the solvent, etc. of the light absorption layer 3,
A spin-coding method that allows control of layer thickness is desirable.

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 dissolving them using multiple types of solvents. Examples include a method of performing spin coding using a light-absorbing material, or a method of performing spin coding using a high boiling point substance.

Next, the light reflection N4 is a metal film, and is formed of, for example, gold, copper, copper, aluminum, or an alloy containing these by means of vapor deposition, sputtering, or the like.

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.

Further, in order to prevent the light reflection layer 4 from being oxidized, another layer such as a tit oxide layer may be provided on the light reflection layer 4.

Next, the protection NI 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 resins, acrylic resins, silicone hard coat resins, 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 reaction agent and a reaction catalyst, apply a liquid mixture of these, and crosslink by irradiating with ultraviolet rays or electron beams.

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

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, imide bonds , polysulfone containing a sulfone bond, polysulfide containing a sulfide bond, and the like. It may be a copolymer compound containing two or more of these bonds, or it may be a Pronk 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-reflecting IW4, the side chain may contain a hydroxyl group, carboxyl group, acrylic group, amine group, vinyl acetate group, etc., or the main chain or side chain may contain a basic acid. may be included.

When forming the retainer layer 5, resin and its reactant,
In addition to the reaction initiator and the like, a solvent and a diluent may be included in order to improve coating properties. In addition, in order to stabilize the coating film, leveling agents, plasticizers, antioxidants,
An antistatic agent, etc. may also be included. Further, if necessary, it may be colored with a pigment or dye.

The stiffness of the resin can be changed depending on the crosslinking density of the crosslinked structure or the concentration of reactive Accoyl, 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, the layers behind the light absorbing layer 3, such as the light reflecting layer 4 and the protective layer 5, are heated to a higher temperature than the layer on which the bits 11 are formed. It is desirable to use a material that has a high deformation temperature and high hardness. 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
℃~70℃, by setting the hardness of the protective layer 5 to 211 or more in terms of pencil hardness, light absorption WJ3
The deformation of the second layer boundary 9 on the light reflective layer 4 side can be suppressed to a small level. As a result, waveform distortion can be suppressed,
Good recording with small B L E R can be performed. 11 As the hardness of R5 decreases, BL
ER tends to increase.

The thermal expansion coefficient α of the protection N5 is set at the operating environment temperature of −15°C.
Within the range of ~70℃. 5×10-5~9.0XI
By keeping it within the range of O-', this maintenance #! Since 1w5 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.

When α is less than 1.5X10-', the substrate 2 expands more greatly due to expansion during heating, so the optical information recording medium 1 warps toward the preservation ffrII5 side, and tensile tension is generated in each layer of the substrate 2. This causes an increase in jitter in the recording pits 11.

When α is larger than 9.0 Delamination occurs between the reflective layer 4 and the protective layer 5.

Note that by setting the shrinkage rate of the protective layer 5 to 12% or less, no cracks will occur in the protective layer Iw5 even when a heat cycle test is performed so that no distortion of the resin remains after curing the protective layer 5. Considering mechanical strength, this shrinkage rate is desirably 10% or less.

Furthermore, the light reflecting layer 4 and the t! An oxidation-resistant layer for preventing oxidation of the light-reflecting layer 4 may be interposed between the first layer 5 and the light-reflecting layer 4 .

[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 absorbed by the optical pickup 1'.
Bit 11 is formed by irradiating W3.

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, due to the relationship with the CD standard, the linear velocity is . 2-1.
It needs to be 4m/sec, and the recording power is 6 to 9m.
W 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.

In this case, when the land 7 between the pregrooves 6 is optically bright due to the thickness of the light absorption layer 3 as described above, the laser is irradiated into the pregroove 6. Preferably, bit 11 is formed.

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

By forming the bit 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 N3 may cause an optical change, thereby forming the bit 11.Furthermore, the components melted and decomposed by the irradiation with the laser beam L1 are diffused into the softened substrate 2. is partially mixed and combined with the components forming the light absorption layer 3.
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 of the bit 11 portion and the reflected light of the portion 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 rg3 is formed only in the storable area outside of the bits.

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 light absorption NI3, there is no possibility of accidental erasure or erroneous recording of other data. There is no risk of recording. Furthermore, user-specific data can be arbitrarily recorded in the area having light absorption M3. Since this recorded data can be reproduced using a signal conforming to the CD standard, it can be reproduced by a commercially available CD player in the same way as the ROMfA information.

[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. .

(Example 1) Width 0.5μm, depth 1100n, and pitch 1.6μm
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 mrn, 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 nm, the a-element refraction 44 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 0.48.

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.

A film with a thickness of 60 nm was deposited on the entire surface of this disk by vacuum evaporation.
An Au film of m thickness was formed. Furthermore, an ultraviolet curable resin (Subinko 1-L) was applied on top of the light reflecting layer, and this 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 Tl m at a linear velocity of 4 rn/see, the optimum power was 7.2 mW. With this power, the EFM 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 reproduced with XR-V73, a laser with a reproduction light 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 reproduction signal. / I top is 0
．． 73, I3/I op is 0.42, block error rate is 1.6 x 10-3, push-pull value is 0.0
It was 67.

This fully satisfies 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 rn/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 0.019. 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 10 cc of diacetone alcohol solvent, and the rotation speed was appropriately changed using the spin cord method. I applied it while letting it work. 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 n abs 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 thickness d of the light absorption layer in the pregroove is 290n.
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 top of this light reflective layer, and was cured by irradiating ultraviolet rays to form a protective FJ# 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/sec, the Nt suitable recording power was 5.2 tnW. When the EFM signal with this power was recorded in the pregroove portion of an optical information recording medium and the recorded portion was reproduced in the same manner as in Example 1, the reflectance was 73.2%, and the I of the reproduced signal was
11/I top is 0°85, I3/It, op is 0
．． 45, the block error rate was 2.2X10-3 and the push-pull value was 0.053. This fully satisfies the standards set by the CD standard.

(Comparative Example 2) A semiconductor laser with a wavelength of 780 nm was used on the land portion of the unrecorded area of the optical information recording medium prepared in Example 2, and a linear velocity of 1. Recording was performed at 4rrt/sec using the optimum recording power. When this recorded portion was reproduced in the same manner as in Example 1, the block error rate was 7.
．． Push-pull during 8X1'O-2 regeneration was 0.022. None of these satisfy the CD standard.

(Example 3) @0.7μm, depth 1100n, and pitch 1.6μm
Thickness: 1.m with spiral pregroove 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.

0.70 g of 1,1'-dibutyl 3 as cyanine dye
．． 3. 3'3'Tetramethyl4,5゜4'
By dissolving 52-dibenzoindodicarbocyanine verchlorate (manufactured by Nippon Kanko Shiki Co., Ltd., NK-3219) in 10 ml of diacetone alcohol, and spin-coding it on the above substrate while changing the rotation speed appropriately. 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.

Also,! The refractive index n of polycarbonate that is the material of the s plate
Since sub is 1.58, the optical phase difference ΔS between the unrecorded pregroove and the land is −0.20.

Also, from the results of [below]], the film thickness d1n at the land is 172
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 thus obtained optical information recording medium using a semiconductor laser with a wavelength of 780 nm at a linear velocity of 1.4 m/sea,
The optimum power was 6.5 mW. EFM with this power
The signal was recorded on the land. At that time, the reflectance of the optical information recording medium was 74°5%, the I top obtained from the eye pattern of the reproduced signal was 0.82, and I 3/
I top is 0.42, block error rate is 1.
The 8X10-3 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 nrn at a linear velocity of 1.4 m/sec and optimal recording power. When this recorded portion was reproduced in the same manner as in Example 3, the block error rate was 8.
5X10-', and 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 thickness dav 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 dIn 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 μrn.

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 an 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 11 of the reproduced signal was
/I top was 0°84, I3/It, op was 0.42, block error rate was 1.9×10−, and push-pull value was 0.052. Moreover, the push-pull of the unrecorded portion was also <0.052. This is a CD
Fully satisfies the standards set forth in the 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.
0XIO-', the push-pull during playback was 0.012. None of these items meet the CD standards.

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

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view of an optical information recording medium 1 according to the present invention, and FIG. Sectional longitudinal sectional view. Figure 3 is a vertical cross-sectional view of the main part of the same state where the bit 11 is formed in the pregroove 6, Figure 4 is a graph of the relationship between the optical phase difference ΔS and the amount of reflected light, and Figure 5 is the optical view before and after recording. Amount of change in target distance ΔLd
and the push-pull change amount Δp before and after recording,
Figure 6 is a graph showing the change in push-pull before and after recording. Figure 7 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. 1. Optical information recording medium 2. Transparent substrate 3. Light absorption layer 4. Light reflection layer 5. Pre-groove 7 Land 8 First layer boundary 9 Second layer boundary 10・Third layer boundary 11 , , , , bit d sub, , , From the first layer boundary 8 between the light absorption layer 3 and the substrate 2 in the land 7 portion to the third layer boundary 8 in the pregroove 6 portion From the second layer boundary 9 between the light absorption layer 3 and the light reflection layer 4 in the land 7 portion to the second layer boundary 9 in the pregroove 6 portion The depth n5ub of the bottom of the layer boundary 9 of the light absorption layer 3 and the substrate 2, the real part nabs of the complex refractive index of the layer located on the substrate 2 side from the first layer boundary 8 of the substrate 2, . , , real part kabs of the complex refractive index of light absorption r#3, ,, imaginary part d of the complex refractive index of light absorption layer 3
av, average film thickness dgr・10 of light absorption layer 3
839. Film thickness d In of the pre-groove 6 portion of the light absorption layer 3 , ..., Film thickness λ8000000 of the land 7 portion of the light absorption layer 3 . Wavelength of reproduction light ΔS , , , Optical phase difference L l , , Recording laser beam L 2 , , ,
,,, Laser optical path diagram for reproduction Fig. 2 Fig. Fig. Anti-vr light amount Pb: Reverse t-bi 7 ~ I Shufu ru 6 + Pr
Recording 7 degrees I 15 Yufu town and repeno and Pant gathering η 7 Hesosia a-Alshishi Pe 1shi figure/'-naba- dav / Enter the diagram and put it in place.

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 when the film thickness of the land portion of the light absorption layer is dln, -0.4≦ΔS≦−0.04, 90nm≦dln≦350nm, and dsub≧40nm. An optical information recording medium characterized by: (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. 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 real part of the complex refractive index of the light absorption layer, and the wavelength of the reproduction light is λ, 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 when the film layer in the land portion of the light absorption layer is dln, −0.4≦ΔS≦−0.04, 90nm≦dln≦350nm, and dsub≧40nm. 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.