JPH04182945A - Optical information recording medium and recording method thereof - Google Patents

Abstract

PURPOSE:To allow the execution of recording at the uniformized width and edges of pits by specifying the ratio between the width and depth of pregrooves and forming the pregrooves deep and narrow. CONSTITUTION:When the depth from the layer boundary between the light absorption layer in the land parts positioned on the right and left of the pregrooves and a substrate to the extreme bottom part of the layer boundary of the parts of the pregrooves is designated as dsub, and the width of the pregrooves is designated as wsub, wsub/dsub<=6.5 is specified. The ratio of the depth to the width of the pits 11 formed by the deformation of the substrate 2 or the decomposition, etc., of the dyes of the light absorption layer 3 is made smaller than a prescribed value in this way. The fine pits 11 having the good edges are formed in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical information recording medium and a recording method thereof, and in particular, by setting the ratio of the depth and width of a pregroove to a predetermined value range. The present invention relates to an optical information recording medium with improved reproduction signal characteristics such as jitter and cocoon talk, and a recording method thereof.

[Prior Art] This type of optical information recording medium includes a light-transmitting substrate on which a pre-groove is formed as a spiral guide groove, a light-absorbing layer provided on the substrate and containing an organic dye, and a light-transmitting layer formed on the substrate and containing an organic dye. Optical information recording that has a light reflective layer provided on an absorption layer and a protective layer further provided on this light reflective layer, allows information to be written and read optically, and whose reproduced signal satisfies the CD standard. The shape of the pre-group of the conventionally known optical information recording medium is such that the track pitch is 1.5 to 1.5 mm. 7μm,
@ is about 0.3 to 0.7 μm, depth is 60 to 1100
It is about n. This optical information recording medium has a recording power of 6 to 9.
Optical pits were formed in the pregroove portions by irradiating mW laser light to deform the substrate by about 30 to 40 nm, thereby recording optical information.

Therefore, optical information can be transmitted under certain conditions (under optimal conditions).
Jitter and block error rate after recording are CD
Although this is sufficient to meet the standards, jitter may increase depending on the recording conditions. Furthermore, even if the jitter is low, the power margin (allowable power for recording) is narrow. Also, when comparing our products, crosstalk is also larger. Note that jitter is the fluctuation or fluctuation of a digital signal in the time axis direction, and crosstalk is a parameter that indicates the influence of signals from adjacent tracks. It is expressed as the ratio of the amplitude of the HF signal in the non-track area).

In other words, the laser power of the recording light differs depending on each recording device, so depending on the recording device used, recording may be performed with a power stronger than the optimum power for a certain optical information recording medium, and the If the pregroove is formed shallowly, the optical bits formed by the recording light will extend to the lands on both the left and right sides of the pregroove, making the pit shape uneven and resulting in a reproduction waveform. In other words, the jitter becomes large.

Furthermore, the optical bits extending to the land portion cause the pits to expand in the width direction relative to the recorded pit depth, resulting in a problem of increased crosstalk in the reproduced waveform.

[Invention tries to solve! l! ! g] The present invention was made in view of the above-mentioned problems, and is an optical information recording medium that uses a light absorption layer and records optical information by deforming a substrate etc. with recording light. It is an object of the present invention to provide an optical information recording medium and a recording method thereof that can clearly obtain a reproduced signal even when recording is performed with high power.

In particular, the purpose of sg is to provide an optical information recording medium and a recording method thereof that can reduce jitter to 40 ns or less in an optical information recording medium that can satisfy the CD standard.

[Means for Solving the Problems] That is, the first invention includes a light-transmitting substrate having a pregroove formed on one main surface, and a material for absorbing recording light provided on the substrate. an optical information recording medium that records information by irradiating the recording light onto the light absorption layer, the light absorption layer in land portions located on the left and right sides of the pregroove; When the depth from the layer boundary between the layer and the substrate to the bottom of the layer boundary in the pregroove portion is dsub, and the width of the pregroove is wsub, wsub
The optical information recording medium is characterized in that /dsub≦6.5.

That is, by reducing the ratio of the width to the depth of the pregroove portion, the area where the pit is formed is limited.

Note that the imaginary part of the complex refractive index of the light absorption layer is kabs, the real part thereof is nabs, the thickness of the light absorption layer is dav, the wavelength of the reproduction light is λ, and ρ
When = nabs-dav/λ, 0.05≦ρ≦
1.6. and k abs≦0.3.

A second invention is an optical information recording medium according to the first invention, characterized in that optical information is recorded by irradiating the recording light from the substrate side onto the light absorption layer. This is a recording method for an information recording medium.

Note that the depth dsub of the pregroove in the present invention
In other words, it is the difference between the deepest part and the top part of the pregroove when the horizontal plane of the board is taken as a reference, and @wsub of the pregroove is the half width (
This refers to the width value at a depth of 1/2 of the depth dsub.
By setting the value of the ratio wsub to 6.5 or less, that is, by making the depth deeper and the width narrower, the absorption effect of the recording light by the light absorption layer is enhanced and the deformation of the substrate, that is, the formation of pits, can be prevented. This is an attempt to make it more clear.

Next, the present invention will be explained in more detail based on FIGS. 1 to 5.

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 1 includes a transparent substrate 2 and a transparent substrate 2.
It has a light absorbing layer N3 formed on top, a light reflecting layer 7W4 formed on this light absorbing layer 3, and a protective layer 5 formed on this light reflecting layer 4. 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 #4.

A spiral pregroove 6 is formed in the substrate 2 as a guide groove. On the left and right of this pregroove 6,
A portion other than the pregroove 6, that is, a land 7 is located.

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 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 protection I'w5 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 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.
Let d sub be the depth to the bottom of the first layer boundary 8 in the pregroove 6 portion.

As mentioned above, the pregroove @wsub and the depth d s
By setting the value of the ratio to ub to 6.5 or less, making the depth deeper and the width narrower, the absorption effect of the recording light L1 by the light absorption layer 3 is enhanced, and the deformation of the substrate 2, that is, the pit 11 This makes the formation more clear.

From the second layer boundary 9 in the land 7 portion to the bottommost depth of the second layer boundary 9 in the pregroove 6 portion (from the surface of the light absorption layer 3 in the land 7 portion to the pregroove 6 The depth of the bottom of the surface at the portion of d abs is defined as d abs.

Let kabs be the imaginary part of the complex refractive index of the light absorption layer 3, and let nabs be the real part.

Let dav be the average film thickness of the light absorbing Nll3. Note that the average film thickness dav here is (volume of light absorption N13)/(
It is represented by the plane 'N' of the region where the light absorption layer 3 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 at the land 7 portion of light absorption #3.

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

Note that the real part nabs of the complex refractive index of the light absorption layer 3,
Film thickness dgr at the pregroove 6 portion of the light absorption layer 3
, the film thickness d1 at the land 7 portion. n, and the optical parameter ΔC defined by the wavelength λ of the reproduction light (reproduction laser beam) r72, ΔC=nabs (dzr
-dln)/λ, it is desirable that 0.12≦△C≦0.75.

That is, the film thickness dgr of the pregroove 6 portion and the land 7
The difference between # and the film thickness din is made larger than before, so that the pregroove 6 portion can absorb more light. Therefore, bits 11 are likely to be formed due to deformation of the substrate 3 or decomposition of the dye, and the land 7 portions do not absorb much light due to their thin film thickness, making it difficult to form bits 11. i.e. bit 11
The bit 11 can be clearly formed without spreading to the land 7 portion.

Furthermore, even when recording with a power stronger than the optimum power, excess heat is absorbed by the optical absorption N3 in the pregroove 6! 17. It is possible to prevent the bit 11 from reaching the land 7 portion.

Furthermore, since the bit 11 is defined as the product of the complex refractive index of the light absorption N3 with respect to the difference between the film thickness dgr of the pregroove 6 portion and the film thickness din of the land 7 portion, the light absorption layer 3 The larger the complex refractive index of the refractive index, the wider the diffraction angle of the diffracted light during reproduction, making it possible to form an ideal bit 1].

In particular, the above-mentioned ΔC=nabs(dgr-din)/λ, 0.12≦
By satisfying the relationship ΔC≦0.75, even if the laser power of the recording light is stronger than the optimum power, the jitter specified in the CD standard can be kept to 40 ns or less. Furthermore,
Modulation degree specified in the CD standard.

Push-pull and crosstalk etc. can also make these better.

In other words, when ΔC is larger than 0.75, the optical phase difference between the land 7 portion and the pregroove 6 becomes too large, making it impossible to reduce the jitter to 40 ns or less, and the modulation depth also increases. It becomes difficult to increase the size. Also, since the contrast in the radial direction increases, tracking becomes difficult, and even if the optical parameter ρ=nabs-dav/λ, which will be explained below, is set to a value within a predetermined range, the reflectance within the pregroove 6 It becomes difficult to increase the ratio to 70% or more.

As a result of the study, it was found that ΔC is preferably 0.4 or less for manufacturing reasons (the difference in film thickness increases and variations tend to occur) or to increase the reflectance.

When 8C is smaller than 0.12, the difference in film thickness between the land 7 portion and the pregroove 6 becomes smaller;
Even if recorded in pregroove 6, bit 11- tends to spread to land 7, resulting in large crosstalk and jitter, and a narrow power window (power margin).

Note that by setting ΔC to 0.15 or more, the jitter can be further improved, specifically, to 30 ns or less.

Next, the optical parameter defined by ρ'' nabs-dav/λ will be explained.

From the results of experiments and simulations by the present inventors, this ρ=nabs-da regarding the film thickness of the light absorption layer 3
We focused on the fact that v/λ is a very important parameter.

That is, in the optical information recording medium 1 having a structure in which a light absorption layer 3 and a light reflection layer N4 are provided on a substrate 2, the reflectance specified in the CD standard is 70% or more, and the modulation of m amplitude in the reproduced signal is performed. r 11/I expressed as degrees
top is 0. 6 or more, and the modulation depth I 3 / I t
op is 0. In order to obtain an output signal of 3 to 0.7, the real part n abs of the complex refractive index of the optical coating layer 3, the film thickness dgr of the pregroove 6 part, and the film thickness di of the land 7 part are required.
p = nabs-dav/ given by the average film thickness with n or the average film thickness dav and the wavelength λ of the reproduction light
It has been found that by setting λ within the range of 0.05≦ρ≦1.6, it is possible to easily increase the reflectance to 70% or more, which conforms to the CD standard.

If ρ is smaller than 0.05, the film thickness dav of the light absorption layer 3 must be made considerably thinner, which is not practical in terms of manufacturing.

Therefore, 0.05≦ρ≦0. In the range of 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.
0.4 to obtain stable recording characteristics with a large degree of modulation.
5±0. It can be said that the range of 1 is the most desirable range.

Furthermore, as shown in Figure 4, 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. 'io
<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.

A graph showing the relationship between ρ and reflectance is expressed as a combined function of an exponential function and 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 counterfeit material on the side where light enters from the light absorption layer 3 is small, the reflectance of the graph 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. 5, the thicker kabs becomes, the greater the attenuation of the reflectance of the entire graph becomes.

Light absorption #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.

Depending on the conditions, it is possible to increase the reflectance at the bottom point of the graph in figure j1!4 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 kabs will also be mentioned.

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

Note that the present inventors have discovered that the numerical setting of kabs is an important parameter. In other words, 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, since recording sensitivity deteriorates as the value approaches O, it is necessary that the value be larger than O.

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. Also, ρ is 0. In the range of 6 to 1.6,
kabs is 0. It is desirable that it is 2 or less.

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. In addition,
It is desirable to mold resin such as polycarbonate by injection molding. Also, other layers on the substrate 2, such as 5i0
It may be coated with a solvent-resistant layer or an enhancement layer such as No. 2.

These materials are processed by means such as injection molding.

Make a mold. The thickness of the substrate 2 is set to comply with the CD standard.
1.1 mm to 1.5 mm is desirable.

As the tracking guide means formed on the surface of the substrate 2 on the light absorption N3 side, it is desirable to use the pregroove 6 (FIGS. 2 and 3) formed in a spiral shape. The pregroove 6 is used to guide tracking when recording a data signal. The pregroove 6 is not limited to a spiral shape, but may be meandering.

The distance between the pregroove 6 and the adjacent pregroove 6, so-called track pitch, is preferably 1.6 μm.

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 layer 3
is preferably a layer containing a light-absorbing organic dye such as a cyanine dye. That is, 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 by means such as a spin coating method.

Next, the light reflection NI4 is formed as necessary and is a metal film, for example, made of gold, copper, aluminum, or an alloy containing these by means of vapor deposition, sputtering, etc. Form. Since it is necessary to have a reflectance of 70% or more, a metal film mainly made of gold or an alloy containing gold is desirable.

In addition, in order to prevent oxidation of the light reflective layer 4, the light reflective NJ4
Other layers such as an oxidation-resistant layer may be provided thereon.

Next, the aforementioned Hot! Similarly, #5 is formed as required, and is made 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.

[Function] Recording can be performed on the optical information recording medium according to the present invention using a known optical information recording device. 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. While this optical information recording medium 1 is rotated by a spindle motor, a laser spot modulated into a signal compliant with the CD standard is tracked by a pickup from the substrate 2 side of the optical information recording medium 1 while tracking according to the tracking guide means. By irradiating the light absorption layer 3, the light absorption layer generates heat, which deforms the substrate 2, thereby forming the bit 11.

Note that during recording, it is desirable to irradiate a laser spot with a wavelength λ of around 780 nm. Further, in relation to the CD standard, the linear velocity must be 1°2 to 1.4 m/sec, and the recording power may be approximately 6 to 9 mW.

In the present invention, the shape of the pregroove 6 is such that the ratio of its @wsub to its depth dsub is 6.5 or less, which is smaller than that of the prior art. In other words, bits 1 are formed due to deformation of the substrate 2 or decomposition of the dye in the light absorption layer 3.
1. The ratio of depth to width of is smaller than a predetermined value. Therefore, a large amount of light-absorbing material is accommodated in the narrow and deep pre-groove 6, and even if recording is performed with a power stronger than the optimum power, excess heat is absorbed by the light-absorbing layer 3 in the pre-groove 6. This can prevent the bit 11 from reaching the land 7 portion.

The heat thus absorbed is trapped here, making it possible to create a clean bit 11 with good edges.

That is, the heat generated by the absorption of the recording laser beam L1 by the light absorption layer 3 is confined within the pregroove 6 with a suppressed rate of diffusion to the outside, and a clear deformed portion (
bit 11).

In general, the thicker the light absorption layer 3 is, the higher the sensitivity is, so the inside of the pregroove 6 has higher sensitivity than the inside of the land 7. Therefore, the recorded pits 11 are difficult to spread over an area wider than the width of the pregroove 6, and it becomes easy to form a clear and large deformed portion on the surface of the substrate 2, physically in a direction perpendicular to the pregroove 6 (optical information Since the radial direction of the recording medium 1 or the width direction of the pregroove 6) is partitioned, the width of the pit 11 does not increase, making it possible to suppress the causes of crosstalk and jitter in the reproduced signal, and to reduce these values. can.

Furthermore, the pits 11 of the optical information recording medium 1 according to the present invention
Because the ratio between the pit depth and the bit width is large, the diffraction angle of the diffracted light (reading laser light) during reproduction is widened.
Ideal pits 11 with small push-pull after recording, large modulation degree, and little jitter are formed. Furthermore, when the refractive index n abs is large, the optical shape of the pits 11 can be made good.

Especially in optical information recording media that can obtain reproduction signals that satisfy the CD standard, d sub/w sub≦6.
．． By satisfying the relationship 5, the jitter can be reduced to 30n.
m or less and which satisfies the CD standard, it is possible to ensure stable playback performance with a normal CD player (see FIG. 6).

Furthermore, the crosstalk specified in the CD standard can also be made good.

Furthermore, the parameter ρ=n regarding the film thickness of light absorption #3
abs-dav/λ is set in the range of 0.05 to 1.6, and the imaginary part kabs of the complex refractive index of the light absorption layer is set to 0.05 to 1.6.
By setting it to 3 or less, an optical information recording medium that satisfies the CD standard and has a low block error rate and low jitter can be obtained.

[Embodiments] Next, embodiments of the optical information recording medium according to the present invention will be described below.

(Example 1) ltllwsub is 390 nm and depth d su
30 parts by weight of cyanine dye No. 1 shown in FIG. 7, 50 parts by weight of cyanine dye N002 shown in FIG. 4-nitroso-
A solution of 4'-iododiphenylamine dissolved in diacetone alcohol at a concentration of 70 g/liter was applied, and a light reflective layer made of gold film was formed, and a UV-cured protective layer was formed on top of that. Then, it was made into a CD.

wsub/dsub=390/130=3.00 and nabs=2. 5. dgr=194 nm,
and d ln=123 nm, and ΔC=0.
It is 23.

Under these conditions, the optimal power is 6, 5 mw, 7,
Recordings were made at 5 mw and 8.5 mw. The respective jitters and crosstalks are shown in the table of FIG. From this table, it can be seen that jitter and crosstalk are small at optimal power, and even if the power is further increased, these increases are small.

Note that the jitter in the pit portion and non-pit portion shown in Figure 9 and the JILO diagram is the total value of the variation in the signal length of the pit portion and non-pit portion when the signal length of 3T and 11T is used as the standard. This is what is shown.

(Comparative example) @wsub is 620 nm and depth d sub is 7
A light absorption layer, a light reflection layer, and a protective layer were formed in the same manner as in Example 1 above on a disc-shaped polycarbonate substrate on which a 0 nm spiral pregroove was formed, and a CD
And so.

wsub/dsub=620/70=8.86,
nabs=2. 5, dgr=151.4nm, and dln=116.4nm, and ΔG=0. 11
It is.

Under these conditions, the optimal power is 7, 0 mw, 8,
Recordings were made at 9.0 mw. The respective jitters and crosstalks are shown in the table of FIG. From this table, it can be seen that at the optimum power, jitter and crosstalk are larger than those of Example 1, and even if the power is further increased, these increasing trends become more pronounced.

(Example 2) A light absorption layer was formed in the same manner as in Example 1 above on a disc-shaped polycarbonate substrate in which a spiral pregroove with a width w sub of 500 nm and a depth d sub of 77 nm was formed. Form a light reflective layer and a protective layer, and
It was set as D.

wsub/dsub==500/77=6.49 and nabs=2. 5, dgr=162nm, and d
ln=115 nm and ΔC=0.15.

For such COD, the recording light wavelength is 770 to 810 nm.
m, and recording was performed at an optimal power of 6.8 mw to 7.8 mw. This jitter is 30nsec at the rise of 3T (T is reference time @), 25nsec at the fall, 11T
The rising time was 23 nsec, the falling time was 20 nsec, and the crosstalk was 0.30.

It can be seen that jitter and crosstalk are small as in Example 1, and even if the power is further increased, their increase is small.

[Effects of the Invention] As described above, according to the present invention, the ratio of the width to the depth of the pregroove is set to a predetermined value of 6.5 or less, and the pregroove is formed deeper and narrower than the conventional one, so that the substrate and light When recording is performed with deformation of the absorbing layer, the deformation of the substrate is limited to the pregroove, so recording can be performed with uniform bit widths and edges. Therefore, it is possible to provide an optical information recording medium that complies with the current CD standard, and in particular can satisfy the standard value of jitter (40 ns or less) defined in the CD standard.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view of an optical information recording medium 1 according to the present invention, and FIG. FIG. 3 is a longitudinal sectional view of the main part of the same, with the bit]-1 formed in the pregroove 6. Fig. 4 is a graph of the relationship between p (=nabs-dav/λ) and reflectance, Fig. 5 is a graph of the relationship between complex refractive index kabS of light absorption N3 and reflectance, and Fig. 6 is a graph of d sub/ Graph showing the relationship between w sub and jitter, Figure 7 is a diagram showing the structural formula of cyanine dye No. 2, Figure 8 is a diagram showing the structural formula of cyanine dye No. 2, and Figure 9 is a diagram showing the implementation of the present invention. FIG. 10 is a table showing the results of Example 1- and FIG. 10 is a table showing the results of Comparative Example 1. 1. Optical information recording medium 2. Transparent substrate 3. Light absorption layer 4. Light reflection layer 5. Protective layer 6, Pre-groove (guide groove) 7,...
, Land 8 , L- layer boundary 9 , Second layer boundary 10 , Third layer boundary 11 , Bit dsuF3. ,. 1. From the first layer boundary 8 between the light absorption layer 3 and the substrate 2 in the land 7 portion to the bottommost depth of the first layer boundary 8 in the pregroove 6 portion d abs of the land 7 Light absorption N
3 and the second layer boundary 9 between the light-reflecting layer 4, the depth nabs of the bottom of the second layer boundary 9 in the pre-groove 6 portion, ---0 real number of the complex refractive index of the light-absorbing layer 3 part k
abs, , , imaginary part da of the complex refractive index of the light absorption layer 3
v,,,,. , average film thickness d gr of light absorption layer 3, ,,,
, , Thickness d In of the light absorption layer 3 at the pregroove 6 portion , , , Thickness wsub of the light absorption layer 3 at the land 7 portion , , Width λ of the pregroove 6 λ208801
6. Wavelength of reproduction light

Claims (1)

[Claims] (1) A light-transmitting substrate with a pregroove formed on one main surface, and a light-absorbing layer provided on the substrate and containing a light-absorbing material that absorbs recording light. and an optical information recording medium in which information is recorded by irradiating the light absorption layer with the recording light, the layer boundary between the light absorption layer and the substrate in land portions located on the left and right sides of the pregroove. , when the depth to the bottom of the layer boundary in the pregroove part is dsub, and the width of the pregroove is wsub, wsu
An optical information recording medium characterized in that b/dsub≦6.5. (2) The imaginary part of the complex refractive index of the light absorption layer is kabs, the real part thereof is nabs, the thickness of the light absorption layer is dav, the wavelength of the reproduction light is λ, and ρ=nabs. - The optical information recording medium according to claim 1, characterized in that, when dav/λ, 0.05≦ρ≦1.6 and kabs≦0.3. (3) A light-transmitting substrate with a pregroove formed on one main surface, and a light-absorbing layer provided on the substrate and containing a light-absorbing substance that absorbs recording light, the light-absorbing layer An optical information recording method for recording information by irradiating the recording light onto the pregroove, the method comprising recording information on the pregroove 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. When the depth to the bottom of the layer boundary in the part is dsub, and the width of the pregroove is wsub, then wsu
A recording method for an optical information recording medium, characterized in that b/dsub≦6.5 and optical information recording is performed by irradiating the recording light onto the light absorption layer from the substrate side.