WO2006088136A1

WO2006088136A1 - Recording medium

Info

Publication number: WO2006088136A1
Application number: PCT/JP2006/302836
Authority: WO
Inventors: Eiji Muramatsu; Kazuo Kuroda; Akira Imamura
Original assignee: Pioneer Corporation
Priority date: 2005-02-18
Filing date: 2006-02-17
Publication date: 2006-08-24
Also published as: JPWO2006088136A1

Abstract

A recording medium (100) includes: (i) a first recording layer (101) holding a recording sensitivity capable of forming a recording mark by a first laser light (405 nm) and having a first light absorption ratio indicating the ratio for absorbing the first laser light (blue) greater than the light absorption ratio for absorbing a second laser light (650 nm); (ii) an intermediate layer (103) having a light reflection ratio for the first laser light greater than the light reflection ratio for the second laser light; and (iii) a second recording layer (102) holding a recording sensitivity capable of forming a recording mark by the second laser light. These components are arranged in this order viewed from the side of the recording medium (100) where light is applied.

Description

recoding media

Technical field

TECHNICAL FIELD [0001] The present invention relates to a technical field of a multilayer recording medium such as a two-layer optical disk, for example.

[0002] Information recording media such as optical discs such as CD-ROM (Compact Disc-Read Only Memory), CD-R (Compact Disc Recordable), and DVD-ROM are described in Patent Documents 1 and 2, etc. As described above, a multilayer type, double layer type, or multiple layer type optical disc in which a plurality of recording layers are laminated on the same substrate has been developed. More specifically, the two-layer type optical disc is positioned as the first layer on the most front side (that is, the side closer to the optical pickup) in view of the irradiation side force of the laser beam when recording with the information recording apparatus. The first recording layer is provided, and a transflective film is further provided on the back side (that is, the side far from the optical pickup force). The second layer has a second recording layer located on the back side of the transflective film via an intermediate layer such as an adhesive layer, and further has a reflective film located on the back side. In an information recording apparatus such as a CD recorder that records such a two-layer type optical disc, the recording laser beam is focused on the first recording layer, so that the first recording layer is focused. Information is recorded by the irreversible change recording method or rewritable method by heating, etc., and the laser light is focused on the second recording layer, so that the information is irreversibly changed by heating to the second recording layer. Recording is performed by a recording method or a rewritable method.

[0003] In particular, as disclosed in Patent Document 3, a recording medium such as a two-layer type optical disk having recording layers that can be recorded at two different wavelengths is relatively short. The so-called intermediate layer (hereinafter referred to as “intermediate layer”) that retains the wavelength selectivity, that is, the reflectance of the laser light of a relatively long wavelength is relatively high and the reflectance of the laser light of other wavelengths is relatively low. A method of inserting a “wavelength selection layer” between two layers has been proposed. Therefore, since the recording medium can be reproduced by either a reproducing apparatus that emits laser light of one wavelength or a reproducing apparatus that emits laser light of another wavelength, it is possible to maintain reproduction compatibility. The

[0004] Patent Document 1: Japanese Unexamined Patent Publication No. 2000-311346

Patent Document 2: Japanese Patent Laid-Open No. 2001-23237

Patent Document 3: Japanese Patent Laid-Open No. 9-237438

Disclosure of the invention

Problems to be solved by the invention

However, in Patent Document 3, for example, when recording is performed with a recording laser beam, for example, on a recording medium such as a two-layer type optical disc having recording layers capable of recording at two different wavelengths. However, it is difficult to reduce the influence between the first recording layer and the second recording layer (hereinafter referred to as “interlayer interference” as appropriate). The

More specifically, as shown in FIG. 7, in Patent Document 3, a transflective film is inserted as an intermediate layer over a recording medium such as a two-layer recording type DVD. Interlayer interference occurs due to the laser beam (recording laser beam) that has the same recording power as in the case of squeezing. FIG. 7 is an enlarged cross-sectional view schematically showing a vertical cross section of the recording layer irradiated with the laser light in the optical disc 300 according to one comparative example.

As shown in FIG. 7, when the recording laser light is irradiated onto the first recording layer 301 disposed on the near side as viewed from the side irradiated with the recording laser light, the recording laser light is irradiated. The laser beam for use affects the second recording layer 302 disposed on the back side through the intermediate layer 303 which is a semi-transmissive reflection film, and inter-layer interference occurs. On the other hand, when the recording laser beam is irradiated onto the second recording layer 302, the recording laser beam affects the first recording layer 301 via the intermediate layer 303, resulting in interlayer interference. .

The present invention has been made in view of, for example, the conventional problems described above. For example, in a recording medium such as a two-layer optical disk, a recording medium capable of reducing interlayer interference due to laser light is provided. The issue is to provide.

Means for solving the problem

[0009] (Recording medium)

In order to solve the above problems, the recording medium of the present invention maintains recording sensitivity capable of forming a recording mark with a first laser beam having a first wavelength (blue LD (Laser Diode)), and the first record. The first light absorptance indicating the ratio of absorbing the one light (blue LD) is the light absorptance to absorb the second laser light (red LD (Laser Diode)) having the second wavelength longer than the first wavelength. Compared to the first recording layer (HD-DVD), which is relatively large, and the light reflectance indicating the ratio of reflecting the first laser light (blue LD), the light reflectance for the second laser light (red LD) And a second recording layer (DVD) that retains recording sensitivity capable of forming the recording mark by the second laser light (red LD), and the first recording layer (HD- (DVD), the intermediate layer, and the second recording layer (DVD) are the first recording layer, the intermediate layer, and the second recording layer as viewed from the side irradiated with the first and second laser beams. Arranged in the order of 2 recording layers.

[0010] According to the recording medium of the present invention, for example, a first recording layer such as HD DVD (High Definition DVD) forms a recording mark with a first laser beam such as a blue LD having a relatively short wavelength. It is set to hold the first absorption rate corresponding to the possible recording sensitivity. In particular, in the present invention, the sum of the light reflectance, the light transmittance, and the light absorption rate in a predetermined layer is configured to be equal to 1.

[0011] Similarly, the second recording layer such as a DVD is set so as to maintain a recording sensitivity capable of forming a recording mark by a second laser beam such as a red semiconductor laser having a relatively long wavelength. Has been.

[0012] The first recording layer is set so that the recording mark can be hardly or completely formed by the second laser light having a relatively long wavelength based on the first absorption rate. And

In addition, the reflectance to the first laser beam (blue LD) is relatively high, so that the reflectance to the second laser beam (red LD) is relatively low, so-called wavelength selectivity is maintained. An intermediate layer is inserted between the first recording layer and the second recording layer. In order to arrange a recording layer with a high recording density on the front side, also considering the side force irradiated with the laser beam, the first recording layer, the intermediate layer, and the second recording layer are arranged in this order from the front side. You may make it do.

[0014] If the intermediate layer is not inserted, the following problems occur. That is, the second recording layer retains recording sensitivity capable of forming a recording mark with the first laser beam (blue LD). Therefore, when the first laser beam is irradiated onto the first recording layer, the first laser beam is irradiated. Light passes through a semi-transmissive reflective layer that does not retain wavelength selectivity and affects the second recording layer, resulting in inter-layer interference. On the other hand, according to the present invention, the first recording layer is set so that the recording mark cannot be formed by the second laser beam, and the intermediate layer is inserted. Therefore, in a recording medium such as a two-layer type optical disc that can be recorded at two different wavelengths, it is possible to further reduce interlayer interference due to, for example, a recording laser beam. That is, when recording laser light such as blue LD is applied to the first recording layer, the recording laser light hardly or completely passes through the wavelength selection layer, so that the recording laser light is directed to the second recording layer. It is possible to further reduce the influence of this, that is, inter-layer interference. In other words, it is possible to further reduce interlayer interference regardless of whether the second recording layer retains or does not retain the recording sensitivity capable of forming a recording mark with blue LD.

[0016] One aspect of the recording medium of the present invention is that the light absorptance in the first recording layer (HD-DVD) and the second recording layer (DVD) varies continuously with the wavelength as a parameter. The first peak wavelength, which is the wavelength at which the light absorption rate in the first recording layer (HD-DVD) is maximum, and the second wavelength, which is the wavelength at which the light absorption rate in the second recording layer (DVD) is maximum. Different from peak wavelength.

[0017] According to this aspect, on the basis of the absorptance of the first recording layer, the first recording layer can be easily set so that the recording mark cannot be formed almost or completely by the second laser beam.

[0018] In the aspect relating to the light absorption rate, the first peak wavelength may be configured to be smaller than the second peak wavelength.

With this configuration, the first recording layer can be set more easily so that the recording mark cannot be formed almost or completely by the second laser beam based on the absorption rate of the first recording layer. It is.

[0020] Further, in the aspect relating to the light absorptance, the first peak wavelength has a length that is larger or smaller by an error amount than 380 nm (nanometers), and the second peak wavelength is greater than 500 nm. You may comprise so that it may be large or small length by the said error amount.

[0021] With this configuration, the first recording layer can be more easily configured so that the recording mark cannot be formed almost or completely by the second laser beam based on the absorption rate of the first recording layer. Can be set. The “error amount” according to the present invention means a constant or variable amount indicating the magnitude of various optical, physical, and mechanical errors. This error amount is, for example, actual Can be determined unambiguously by empirical, empirical, theoretical or simulation

[0022] In another aspect of the recording medium of the present invention, the first recording layer (HD-DVD) cannot form the recording mark by the second laser light (red LED)! /.

[0023] According to this aspect, it is possible to further reduce the interlayer interference due to the second laser light.

[0024] In this aspect relating to the light absorptance, the light absorptance for absorbing the second laser light (red LED) in the first recording layer (HD-DVD) is configured to be zero. Anyway!

[0025] With this configuration, it is possible to further reduce interlayer interference due to the second laser light.

In another aspect of the recording medium of the present invention, the first light absorptance and the second recording layer (DV

The second light absorptance indicating the ratio of absorbing the second laser light (red LED) in D) is set to be smaller than the maximum value.

[0027] According to this aspect, it is possible to increase the light reflectivity with respect to the first laser light and the second laser light having the reproduction power, so that the reproduction quality is improved in addition to the recording quality of the recording medium. Is possible.

[0028] In the aspect related to the light absorption rate, the first light absorption rate and the second light absorption rate are:

It may be configured to be close to 1 to 0.3.

[0029] With this configuration, it is possible to further improve the reproduction quality in addition to the recording quality of the recording medium.

[0030] In another aspect of the recording medium of the present invention, a light reflectance of the intermediate layer with respect to the first laser light (blue LD) is close to 0.4 to 0.8. The light reflectivity for laser light (red LED) is approaching 0.1 to 0.3.

[0031] According to this aspect, it is possible to further improve the reproduction quality in addition to the recording quality of the recording medium.

In another aspect of the recording medium of the present invention, the first wavelength is close to 405 nm (nanometer), and the second wavelength is close to 650 nm.

[0033] According to this aspect, the first laser light has a relatively short wavelength, such as a blue LD. Laser light can be applied, and as the second laser light, for example, a relatively long and wavelength laser light such as a red semiconductor laser can be applied.

In another aspect of the recording medium of the present invention, the first recording layer (HD-DVD) and the second recording layer (DVD) contain a cyanine organic dye.

According to this aspect, the first recording layer that retains the first light absorptance described above can be realized relatively easily.

In another aspect of the recording medium of the present invention, the recording mark holds predetermined recording information.

[0037] According to this aspect, it is possible to record the recording information with the recording mark having improved recording quality. In addition, it becomes possible to record predetermined recording information on the first recording layer and the second recording layer with the density of the recording mark determined based on the size of the wavelength, that is, the recording density. .

[0038] These effects and other advantages of the present invention will become more apparent from the embodiments described below.

[0039] As described above, according to the recording medium of the present invention, the first recording layer, the intermediate layer, and the second recording layer are provided when viewed from the side irradiated with the laser beam. Therefore, in a recording medium such as a two-layer type optical disc that can be recorded at two different wavelengths, it is possible to further reduce interlayer interference due to recording laser light, for example.

Brief Description of Drawings

FIG. 1 is a schematic plan view (FIG. 1 (a)) showing a basic configuration of an optical disc 100 according to an embodiment of a recording medium of the present invention, and a schematic cross section of the optical disc at a cutting plane “X”. It is a diagram (Fig. 1 (b)).

FIG. 2 is an enlarged cross-sectional view schematically showing a vertical cross section of a recording layer irradiated with laser light in an optical disc 100 according to an embodiment of a recording medium of the present invention.

FIG. 3 is a graph showing the light absorptance, which is the ratio of absorbing light, with the wavelength as a parameter, in the first recording layer and the second recording layer constituting the embodiment of the recording medium of the present invention.

[FIG. 4] A specific example of the organic dye constituting the first recording layer and the second recording layer constituting the embodiment of the recording medium of the present invention (FIG. 4 (a) and FIG. 4 (b)). It is a chemical formula shown. FIG. 5 is a graph showing light reflectance, which is a ratio of reflecting light, using wavelength as a parameter, in an intermediate layer constituting an embodiment of the recording medium of the present invention.

FIG. 6 is an enlarged cross-sectional view schematically showing a vertical cross section of a recording layer irradiated with laser light in an optical disc 200 according to another comparative example.

FIG. 7 is an enlarged cross-sectional view schematically showing a vertical cross section of a recording layer irradiated with laser light in an optical disc 300 according to a comparative example of FIG.

Explanation of symbols

[0041] 100 optical disc

101 1st recording layer

102 Second recording layer

103 Middle layer

104 and 105 polycarbonate layers

LB1 laser light (blue semiconductor laser)

LB2 laser light (red semiconductor laser)

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the best mode for carrying out the present invention will be described in each embodiment in order with reference to the drawings.

(1) Recording medium of the present invention

Hereinafter, with reference to FIG. 1 to FIG. 5, description will be given on embodiments of the recording medium of the present invention.

[0043] (1— 1) Basic configuration

First, an outline of the basic configuration of an optical disc according to an embodiment of the recording medium of the present invention will be described with reference to FIG. Here, FIG. 1 (a) is a schematic plan view showing the basic configuration of the optical disk 100 according to the embodiment of the recording medium of the present invention, and FIG. It is a schematic sectional drawing of an optical disk.

As shown in FIG. 1 (a), the optical disc 100 has a disk shape having a center hole 10 and a diameter of about 12 cm, for example, like a DVD. However, it goes without saying that this shape and size are not limited to this, and various sizes and shapes may be adopted. Nor.

As shown in FIG. 1 (b), the optical disc 100 is a multilayer type recording medium in which a plurality of recording layers such as a two-layer type are stacked.

Specifically, for example, when viewed from the side irradiated with two types of laser beams LB1 and LB2 (the lower side in FIG. 1 (b)), the first recording of the polycarbonate layer 104, for example, an HD-DVD or the like. The layer 101 includes an intermediate layer 103 that retains wavelength selectivity, for example, a second recording layer 102 such as a DVD, and a polycarbonate layer 105.

[0047] More specifically, the first recording layer 101 is a recording layer that retains recording sensitivity capable of forming a recording mark by the laser beam LB1. Here, the laser beam LB1 according to the present embodiment is a laser beam having a relatively short wavelength such as a blue LD having a wavelength of 405 nm. Note that the first recording layer 101 has a light absorptivity (see FIG. 3 to be described later) capable of forming a recording mark by the laser beam LB1 holding the recording power. At the same time, it may be configured to have a light reflectivity capable of reflecting the laser beam LB1 holding the reproduction power.

[0048] The second recording layer 102 is a recording layer that maintains a recording sensitivity with which a recording mark can be formed by the laser beam LB2. Here, the laser beam LB2 according to the present embodiment is a laser beam having a relatively long wavelength such as a red laser beam having a wavelength of 650 ηm, for example. Note that the second recording layer 102 has a light absorptivity (see FIG. 3 described later) by which a recording mark can be formed by the laser beam LB2 that retains the recording power. At the same time, a total reflection film capable of reflecting the laser beam LB2 holding the reproduction power may be laminated.

[0049] The intermediate layer (wavelength selection layer) 103 has a characteristic that the reflectance with respect to laser light of one wavelength is relatively high and the reflectance with respect to laser light of another wavelength is relatively low. Long selectivity is maintained.

[0050] The polycarbonate layers 104 and 105 may be configured to have a thickness of 0.6 mm, for example.

[0051] (1 2) Recording characteristics

Next, with reference to FIGS. 2 to 5, the recording characteristics of the optical disc according to the embodiment of the recording medium of the present invention will be described. FIG. 2 is an enlarged view schematically showing a vertical section of a recording layer irradiated with laser light in the optical disc 100 according to the embodiment of the recording medium of the present invention. It is sectional drawing. FIG. 3 is a graph showing the light absorptance, which is the ratio of absorbing light, with the wavelength as a parameter, in the first recording layer and the second recording layer constituting the embodiment of the recording medium of the present invention. FIG. 4 shows one specific example (FIG. 4 (a) and FIG. 4 (b)) of the organic dye constituting the first recording layer and the second recording layer constituting the embodiment of the recording medium of the present invention. It is a chemical formula. FIG. 5 is a graph showing the light reflectance, which is the ratio of reflecting light, with the wavelength as a parameter, in the intermediate layer constituting the embodiment of the recording medium of the present invention. In FIG. 3, the vertical axis indicates the light absorptance, and the horizontal axis indicates the wavelength. In addition, the vertical axis in FIG. 5 indicates the light reflectance, and the horizontal axis indicates the wavelength.

As shown in FIG. 2, when the first recording layer 101 is irradiated with the laser beam LB1, a recording mark can be formed based on the recording sensitivity of the first recording layer 101. is there. Specifically, as indicated by “point A” in FIG. 3, the first recording layer 101 retains recording sensitivity corresponding to the light absorption rate “A1” for the laser beam LB1 having a wavelength of 405 nm. More specifically, the first recording layer 101 is composed of a cyanine organic dye as shown in FIG. 4 (a). According to the research by the present inventor, it has been found that the light absorption rate of the first recording layer 101 composed of such an organic dye exhibits a maximum value with respect to a laser beam having a wavelength of about 380 nm. Yes. The first recording layer 101 can absorb light having a wavelength of approximately 80 nm to 600 nm. The light absorptance with the wavelength of the first recording layer 101 as a parameter is indicated by a dotted parabola in FIG.

As described above, the intermediate layer 103 (“wavelength selection layer”) that retains wavelength selectivity is inserted between the first recording layer and the second recording layer. This intermediate layer 103 has a characteristic that the reflectivity with respect to laser light of one wavelength is relatively high, and the reflectivity with respect to laser light of other wavelengths is relatively low. is doing. Specifically, as indicated by “point B” in FIG. 5, the light reflectivity of the intermediate layer 103 with respect to the laser beam LB1 having a wavelength of 405 nm is set to be relatively large. Accordingly, since the intermediate layer 103 reflects the laser beam LB1, the laser beam LB1 cannot reach the second recording layer 102.

As a result, when the first recording layer 101 is irradiated with the recording laser beam LB1 such as blue LD, the recording laser beam hardly or completely passes through the intermediate layer 103. No. 2 It is possible to further reduce the influence on the recording layer 102, that is, interlayer interference.

Returning to FIG. 2 again, on the other hand, when the second recording layer 102 is irradiated with the laser beam LB2, a recording mark is formed based on the recording sensitivity of the second recording layer 102. It is possible. Specifically, as indicated by “point E” in FIG. 3, the second recording layer 102 retains recording sensitivity corresponding to the light absorption rate “E1” for the laser beam LB2 having a wavelength of 650 nm. More specifically, as shown in FIG. 4 (b), the second recording layer 102 has a structure portion represented by (—CH =) in FIG. 4 (a) (− CH = CH-CH) and modified cyanine organic dyes. According to the research by the present inventor, it has been found that the light absorption rate of the second recording layer 102 composed of such an organic dye shows a maximum value for a laser beam having a wavelength of about 500 nm. is doing. The second recording layer 102 can absorb light having a wavelength of about 250 ηm to 750 nm. The optical absorptance power with the wavelength of the second recording layer 102 as a parameter is indicated by a thick parabola in FIG.

[0056] Power! Even if the laser beam LB2 passes through the first recording layer 101, no recording mark is formed based on the recording sensitivity of the first recording layer 101. Specifically, as indicated by “C” in FIG. 3, the first recording layer 101 has a light absorptance of “zero” for the laser beam LB2 having a wavelength of 650 nm. Is hardly or completely retained.

In addition, as described above, the intermediate layer 103 (“wavelength selection layer”) that retains wavelength selectivity is inserted between the first recording layer and the second recording layer. Specifically, as indicated by “point D” in FIG. 5, the light reflectance of the intermediate layer 103 with respect to the laser beam LB2 having a wavelength of 650 nm is set to be relatively small. Therefore, since the intermediate layer 103 transmits the laser beam LB2, the laser beam LB2 can reach the second recording layer 102.

As a result, for example, even if the recording laser light LB2 such as red laser light passes through the first recording layer 101 and is focused on the second recording layer 102, the first recording layer 101 is irradiated. Effect, i.e., little or no inter-layer interference.

[0059] (2) Examination of effects of the recording medium of the present invention

Subsequently, the recording medium of the present invention will be described with reference to FIGS. 1 to 5 as appropriate in addition to FIG. The effects of the embodiment will be examined. FIG. 6 is an enlarged cross-sectional view schematically showing a vertical cross section of a recording layer irradiated with laser light in an optical disk 200 according to another comparative example.

First, the operational effects of the recording medium according to the present invention will be examined based on the following three conditions (i) to (iii).

That is, in this embodiment, (i) a recording layer having a high recording density is disposed on the near side as viewed from the side irradiated with the laser light, and disposed on the near side, for example, HD. — The first recording layer 101 such as a DVD is set so as to maintain a recording sensitivity capable of forming a recording mark by a blue LD having a relatively short wavelength.

(Ii) The first recording layer 101 is set so that a recording mark cannot be formed by a red laser beam having a relatively long wavelength.

(Iii) The reflectivity for laser light of one wavelength is relatively high, and the reflectivity for laser light of another wavelength is relatively low. It is inserted between the first recording layer 101 and the second recording layer 102.

[0064] Let us consider a case where only the conditions (i) and (ii) among the above-mentioned three conditions (i) to (iii) are satisfied with reference to FIG. In this case, as shown in FIG. 6, the first recording layer 201 does not maintain recording sensitivity capable of forming a recording mark by a red laser beam having a relatively long wavelength. Therefore, for example, even if the recording laser light force such as red laser light passes through the first recording layer 201 and is focused on the second recording layer 202, the influence on the first recording layer 201, that is, interlayer interference Hardly or completely occurs.

[0065] However, since the second recording layer 202 maintains recording sensitivity capable of forming a recording mark with the blue LD, the second recording layer 202 is irradiated with the recording laser beam power of the blue LD, for example, to the first recording layer 201. In this case, the recording laser light passes through the transflective layer 203 that does not retain the wavelength selectivity, and affects the second recording layer (DVD), resulting in interlayer interference.

[0066] In contrast, according to the recording medium of the present invention, since the three conditions (i) to (iii) are satisfied, a two-layer type optical disc or the like that can be recorded with two different wavelengths respectively. In this recording medium, it is possible to further reduce interlayer interference due to the recording laser beam. That is, when the recording laser beam such as blue LD is applied to the first recording layer (HD-DVD), Since the recording laser light hardly passes or completely passes through the wavelength selection layer, the influence on the second recording layer (DVD), that is, interlayer interference can be further reduced. In other words, the second recording layer (DVD) force Blue LD can reduce the interference between layers regardless of whether or not the recording sensitivity at which recording marks can be formed is maintained.

Further, in the above-described embodiments, the power described for the optical disc 100 as an example of the recording medium is not limited to the optical disc. The present invention is not limited to the optical disc, and is applicable to various recording media compatible with high-density recording or high transfer rate. Is also applicable.

[0068] The present invention is not limited to the above-described embodiments, but can be appropriately changed within the scope of the appended claims and the entire specification without departing from the gist or philosophy of the invention which can be read. Is also included in the technical scope of the present invention.

Industrial applicability

[0069] The recording medium according to the present invention can be used for a multilayer recording medium such as a two-layer optical disk.

Claims

The scope of the claims

[1] The first light absorptance indicating the ratio of absorbing the first laser light while maintaining the recording sensitivity capable of forming a recording mark by the first laser light of the first wavelength is longer than the first wavelength. A first recording layer that is larger than the light absorptance of absorbing the second laser beam of two wavelengths,

An intermediate layer having a light reflectivity indicating a ratio of reflecting the first laser light, which is larger than a light reflectivity for the second laser light;

A second recording layer having recording sensitivity capable of forming the recording mark by the second laser beam;

With

The first recording layer, the intermediate layer, and the second recording layer are the first recording layer, the intermediate layer, and the second recording layer as viewed from the side irradiated with the first and second laser beams. A recording medium characterized by being arranged in the order of two recording layers.

[2] The light absorptance in the first recording layer and the second recording layer is a wavelength at which the light absorptance in the first recording layer changes continuously with the wavelength as a parameter and the light absorptance in the first recording layer is maximum. 2. The recording medium according to claim 1, wherein the peak wavelength is different from the second peak wavelength, which is a wavelength at which the light absorption rate in the second recording layer is maximized.

[3] The recording medium according to claim 2, wherein the first peak wavelength is smaller than the second peak wavelength.

[4] The first peak wavelength has a length that is larger or smaller by an error amount than 380 nm (nanometer), and the second peak wavelength has a length that is larger or smaller than the error amount by more than 500 nm. The recording medium according to claim 3, wherein the recording medium is a recording medium.

5. The recording medium according to claim 1, wherein the recording mark cannot be formed on the first recording layer by the second laser beam.

6. The recording medium according to claim 5, wherein the first recording layer has a light absorptance for absorbing the second laser light of zero.

[7] The first light absorptance and the second light absorptance indicating the ratio of absorbing the second laser light in the second recording layer are set to be smaller than the maximum value !, The recording medium according to claim 1, wherein the recording medium is characterized in that:

[8] The recording medium according to claim 7, wherein the first light absorptance and the second light absorptance are close to 0.1 to 0.3.

[9] The light reflectance for the first laser light in the intermediate layer is close to 0.4 to 0.8, and the light reflectance for the second laser light is 0.1 to 0.00. The recording medium according to claim 1, wherein the recording medium is close to 3.

[10] The first wavelength is close to 405 nm (nanometers), and the second wavelength is 65

The recording medium according to claim 1, wherein the recording medium is close to Onm.

[11] The recording medium according to [1], wherein the first recording layer and the second recording layer contain a cyanine organic dye.

12. The recording medium according to claim 1, wherein the recording mark holds predetermined recording information.