JP2003123318A - Optical recording medium - Google Patents
Optical recording mediumInfo
- Publication number
- JP2003123318A JP2003123318A JP2001317177A JP2001317177A JP2003123318A JP 2003123318 A JP2003123318 A JP 2003123318A JP 2001317177 A JP2001317177 A JP 2001317177A JP 2001317177 A JP2001317177 A JP 2001317177A JP 2003123318 A JP2003123318 A JP 2003123318A
- Authority
- JP
- Japan
- Prior art keywords
- film
- type super
- resolution
- aperture
- recording medium
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
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- Optical Record Carriers And Manufacture Thereof (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、再生ビーム光を照
射して情報の再生を行う再生専用型の光記録媒体に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a read-only optical recording medium that reproduces information by irradiating a reproduction beam of light.
【０００２】[0002]
【従来の技術】一般に、再生ビーム光の照射により情報
の再生を行う光ディスク等の光記録媒体は、高度情報社
会における記録媒体の中心的役割の担い手として特に注
目されている。この光記録媒体は、音声、映像、コンピ
ューターデータ等の情報の蓄積に利用され、さらなる高
度情報化と共に、その高密度化、大容量化が期待されて
いる。光ディスクシステムにおける情報の高密度化技術
としては、半導体レーザ光の短波長化、対物レンズの高
ＮＡ（開口数）化と共に媒体の改良を行う超解像技術が
挙げられる。この超解像技術は当初、光磁気ディスク特
有の技術として提案されたが、その後、再生ビームのス
ポット内に生じる温度分布を利用し、実効的に再生ビー
ム径より小さな光学的開口を形成できる超解像膜を用い
再生専用型ディスクや相変化型光ディスク等での提案が
なされ、様々なディスクに適用可能であることが明らか
になった。現在提案されている超解像膜にはサーモクロ
ミック膜、相変化材料膜、Sb膜、フォトクロミック膜等
があるが、繰り返し再生での安定性や開口サイズの制御
性など種々の課題があり、実用されるまでには至ってい
ない。2. Description of the Related Art In general, an optical recording medium such as an optical disk which reproduces information by irradiating a reproducing beam of light is particularly attracting attention as a key player of the recording medium in the advanced information society. This optical recording medium is used for accumulating information such as voice, video, computer data, etc., and it is expected that the density and capacity of the optical recording medium will be increased as the information becomes more sophisticated. As a technique for increasing the information density in the optical disc system, there is a super-resolution technique for improving the medium while shortening the wavelength of the semiconductor laser light and increasing the NA (numerical aperture) of the objective lens. This super-resolution technology was originally proposed as a technology peculiar to a magneto-optical disk, but after that, by utilizing the temperature distribution generated within the spot of the reproduction beam, it is possible to effectively form an optical aperture smaller than the reproduction beam diameter. Proposals have been made for read-only discs and phase-change optical discs using a resolution film, and it has been clarified that it can be applied to various discs. Currently proposed super-resolution films include thermochromic film, phase change material film, Sb film, photochromic film, etc., but they have various problems such as stability in repeated reproduction and controllability of aperture size, It has not reached the point.
【０００３】一方、このような開口型の超解像膜とは別
に、微小開口を用いず超解像効果を得ることができる技
術が提案された（T.Kikuwa et al.: Jpn.J.Appl.Phys.
40(2001)1624）。この技術はSuper-ROMとよばれ、再生
専用型ディスクの反射膜に、従来用いられてきたAlやA
ｕの代わりにMo、W、Si、Ge等を用いることにより、開
口型の超解像膜を用いることなく従来の光学系では再生
できなかった回折限界以下の微小な記録ピットの再生が
可能となるものである。以下の説明においては、上記の
様に微小開口を用いてレーザスポットを実効的に小さく
することなく、回折限界以下の記録信号を読み出すこと
が可能な膜を非開口型の超解像膜と定義する。この詳細
な再生メカニズムは検討中であるが、回折限界以下の記
録ピットでも再生信号が得られ、今後の高密度化の要求
に応えることのできる可能性がある技術である。また、
この開口型の超解像膜での課題のひとつであった繰り返
し再生での安定性は非常に高く、実用的な特性も期待で
きる技術である。On the other hand, in addition to such an aperture-type super-resolution film, a technique has been proposed which can obtain a super-resolution effect without using a minute aperture (T. Kikuwa et al .: Jpn. J. Appl.Phys.
40 (2001) 1624). This technology is called Super-ROM and is used for the reflective film of read-only discs, such as Al and A
By using Mo, W, Si, Ge, etc. instead of u, it is possible to reproduce minute recording pits below the diffraction limit, which could not be reproduced by conventional optical systems, without using an aperture type super-resolution film. It will be. In the following description, a film capable of reading a recording signal below the diffraction limit without effectively reducing the laser spot by using the minute aperture as described above is defined as a non-aperture type super-resolution film. To do. This detailed reproduction mechanism is under study, but it is a technology that can obtain a reproduction signal even in recording pits below the diffraction limit and can meet the demand for higher density in the future. Also,
This is a technology that has extremely high stability in repeated reproduction, which was one of the problems with this aperture-type super-resolution film, and can be expected to have practical characteristics.
【０００４】[0004]
【発明が解決しようとする課題】しかしながら、現在の
ところ上記した非開口型の超解像膜を用いた記録媒体で
は、回折限界以下の微小ピットでの再生出力は実用的に
十分な値が得られておらず、更なる信号強度の増大が必
要である。そこで、本発明は以上のような問題点に着目
し、これを有効に解決すべく創案されたものであり、そ
の目的は、非開口型の超解像膜を用い回折限界以下の微
小ピットでの信号強度を増大させることが可能な光記録
媒体を提供することにある。However, at present, in the recording medium using the above-mentioned non-aperture type super-resolution film, the reproduction output in the minute pits below the diffraction limit is practically sufficient. However, further signal strength increase is required. Therefore, the present invention focused on the above problems and was devised to effectively solve the problems, and its purpose is to use a non-aperture type super-resolution film in a minute pit below the diffraction limit. It is an object of the present invention to provide an optical recording medium capable of increasing the signal strength of.
【０００５】[0005]
【課題を解決するための手段】請求項１に規定する発明
は、再生ビーム光に対する反射率の変化により信号を読
み出すことができるようにした光記録媒体において、光
透過性の基板上に非開口型の超解像膜と開口型の超解像
膜とをこの順に積層したことを特徴とする光記録媒体で
ある。請求項２に規定する発明は、再生ビーム光に対す
る反射率の変化により信号を読み出すことができるよう
にした光記録媒体において、光透過性の基板上に非開口
型の超解像膜と金属微小散乱体を含む微小散乱体膜とを
積層されていることを特徴とする光記録媒体である。According to the invention defined in claim 1, in an optical recording medium in which a signal can be read by a change in reflectance with respect to a reproducing beam light, a non-aperture is formed on a light transmissive substrate. An optical recording medium is characterized in that a type super-resolution film and an aperture type super-resolution film are laminated in this order. The invention defined in claim 2 is an optical recording medium in which a signal can be read by a change in reflectance with respect to a reproducing beam light, and a non-aperture type super-resolution film and a metal microscopic film are provided on a light-transmissive substrate. An optical recording medium is characterized in that a minute scatterer film including a scatterer is laminated.
【０００６】この場合、例えば請求項３に規定するよう
に、前記開口型の超解像膜は、サーモクロミック膜で形
成されている。また、例えば請求項４に規定するよう
に、前記微小散乱体は、誘電体膜中に非固溶な金属の微
粒子を分散させている。In this case, for example, as defined in claim 3, the aperture type super-resolution film is formed of a thermochromic film. Further, for example, as defined in claim 4, the fine scatterer has fine particles of non-solid solution metal dispersed in the dielectric film.
【０００７】[0007]
【発明の実施の形態】以下に、本発明に係る光記録媒体
の一実施例を添付図面に基づいて詳述する。図１は本発
明に係る光記録媒体を示す断面図であり、図１（Ａ）は
本発明の第１の実施例の断面図を示し、図１（Ｂ）は本
発明の第２の実施例の断面図を示す。また、ここでは光
記録媒体として光ディスクを例にとって説明する。図１
（Ａ）に示す第１の実施例において、１はポリカーボネ
ート樹脂等よりなる光透過性の基板であり、この基板１
上に非開口型の超解像膜２，開口型の超解像膜３、誘電
体膜４，保護膜５が順次積層させて形成されている。そ
して、再生ビーム光Ｌは基板１側から入射され、この再
生ビーム光Ｌは、先に非開口型の超解像膜２に照射さ
れ、その後、開口型の超解像膜３に照射される構成とな
っている。そのため再生ビーム光Ｌが開口型の超解像膜
３まで到達するように非開口型の超解像膜２の透過率が
調整されていることが望ましい。BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an optical recording medium according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a sectional view showing an optical recording medium according to the present invention, FIG. 1 (A) shows a sectional view of a first embodiment of the present invention, and FIG. 1 (B) shows a second embodiment of the present invention. A cross-sectional view of an example is shown. An optical disc will be described as an example of the optical recording medium. Figure 1
In the first embodiment shown in (A), 1 is a light-transmissive substrate made of polycarbonate resin or the like.
A non-aperture type super-resolution film 2, an aperture type super-resolution film 3, a dielectric film 4, and a protective film 5 are sequentially laminated on top of this. Then, the reproduction beam light L is incident from the substrate 1 side, and the reproduction beam light L is first irradiated on the non-aperture type super-resolution film 2 and then on the opening type super-resolution film 3. It is composed. Therefore, it is desirable that the transmittance of the non-aperture type super-resolution film 2 be adjusted so that the reproduction beam light L reaches the aperture-type super-resolution film 3.
【０００８】ここで、上記非開口型の超解像膜２として
は、例えばＳｉ膜が用いられ、上記開口型の超解像膜３
としては例えばサーモクロミック膜が用いられ、上記誘
電体膜４としては例えばＺｎＳ−ＳｉＯ2 膜が用いら
れ、また、上記保護膜５としては例えば紫外線硬化樹脂
が用いられる。従来から提案されている開口型の超解像
膜のみを用いた場合、膜の積層順は、一般に再生ビーム
光の入射側に超解像膜が配置されており、記録膜、或い
は反射膜はその奥に配置される。この時、開口型の超解
像膜は微小開口を形成することによりビーム径を絞り、
超解像効果を起こす役割を担っている。これに対して、
本発明における超解像効果は非開口型の超解像膜が担っ
ており、再生ビーム光の絞り込みがない。この非開口型
の超解像膜の再生原理はまだ明確になっていないが、記
録ピット周辺の電磁気特性（プラズモン等）と電磁場の
振動との相互作用が関連していると推測されている。例
えば、その推測は以下のようである。一般に波長以下の
微小開口や微小散乱体に光を照射することにより電磁場
（エバネッセント場）が生成されることが知られてい
る。本発明の第１の実施例においても、開口型の超解像
膜がつくる微小開口の存在により新たに電磁場が形成さ
れる。この新たに形成された電磁場と非開口型の超解像
膜の電磁場が相互作用することにより回折限界以下の信
号強度の増大がはかられる。Here, for example, a Si film is used as the non-aperture type super-resolution film 2, and the aperture type super-resolution film 3 is used.
For example, a thermochromic film is used as the dielectric film 4, a ZnS—SiO 2 film is used as the dielectric film 4, and an ultraviolet curable resin is used as the protective film 5. When only the aperture-type super-resolution film proposed in the past is used, the film stacking order is generally such that the super-resolution film is arranged on the incident side of the reproduction beam light, and the recording film or the reflection film is It is placed in the back. At this time, the aperture-type super-resolution film narrows the beam diameter by forming a minute aperture,
It plays a role in producing the super-resolution effect. On the contrary,
The non-aperture type super-resolution film bears the super-resolution effect in the present invention, and the reproduction beam light is not narrowed down. Although the reproducing principle of this non-aperture type super-resolution film has not been clarified yet, it is presumed that the interaction between the electromagnetic characteristics (plasmon etc.) around the recording pit and the vibration of the electromagnetic field is related. For example, the speculation is as follows. It is generally known that an electromagnetic field (evanescent field) is generated by irradiating light to a minute aperture or a minute scatterer having a wavelength or less. Also in the first embodiment of the present invention, an electromagnetic field is newly formed due to the existence of the minute aperture formed by the aperture type super-resolution film. The newly formed electromagnetic field interacts with the electromagnetic field of the non-aperture type super-resolution film to increase the signal intensity below the diffraction limit.
【０００９】また、図１（Ｂ）に示す第２の実施例にお
いては、同じく光透過性の基板１上に、非開口型の超解
像膜２、金属微小散乱体を含む微小散乱体膜６及び保護
層５が順次積層されている。尚、図１（Ａ）に示す部材
と同一部材については同一符号を付している。このよう
に、第２の実施例の特徴は、金属微小散乱体を含む微小
散乱体膜６を非開口型の超解像膜２と積層する点にあ
る。ここで用いる金属微小散乱体は光の照射により表面
プラズモンを生成する。この表面プラズモンの励起によ
り、非開口型の超解像膜の電磁場が増強されると推定さ
れる。この時の金属微小散乱体を形成する金属微粒子の
粒径、密度が増強の度合いに影響を与えるため、実際の
光ディスクシステムにおいては、記録信号に見合った粒
径、密度を適宜調整する必要がある。この微小散乱体膜
６としては、例えば金属微粒子が分散された誘電体膜が
用いられる。Further, in the second embodiment shown in FIG. 1B, a non-aperture type super-resolution film 2 and a minute scatterer film containing a metal minute scatterer are also formed on a substrate 1 which is also transparent to light. 6 and the protective layer 5 are sequentially stacked. The same members as those shown in FIG. 1A are designated by the same reference numerals. As described above, the feature of the second embodiment is that the fine scatterer film 6 containing the metal fine scatterer is laminated with the non-aperture type super-resolution film 2. The metal microscatterer used here generates surface plasmons by irradiation with light. It is estimated that the excitation of this surface plasmon enhances the electromagnetic field of the non-aperture type super-resolution film. At this time, since the particle size and density of the metal fine particles forming the metal microscattering body affect the degree of enhancement, it is necessary to appropriately adjust the particle size and density corresponding to the recording signal in the actual optical disc system. . As the fine scatterer film 6, for example, a dielectric film in which fine metal particles are dispersed is used.
【００１０】そして、上記第１及び第２の実施例の技術
的構成をより明確にするため、微小開口や金属微小散乱
体を持たない膜（例えばAu、Ag等の金属膜）と非開口型
の超解像膜とを積層した光ディスクを作成して再生を行
うと信号強度はむしろ低下する傾向が見られる。これら
のことより、非開口型の超解像膜と開口型の超解像膜と
を組み合わせる事を特徴とする前述の第１の実施例にお
いて、開口型の超解像膜の役割は、従来なされている提
案の様に微小開口を形成してビームを絞る事ではなく、
波長以下の微小開口を形成して電磁気的相互作用を生じ
させる事である。そして、その電磁気的相互作用を生じ
させるためには、ビームに対する積層順が重要になる。
先に開口型の超解像膜に再生ビーム光が当たると非開口
型の超解像効果が発生しないか、発生しても微弱なた
め、開口型の超解像効果のみの作用となる。従って、光
透過性の基板１上のビーム入射側に非開口型の超解像膜
２が配置され、その上に開口型の超解像膜３が積層され
ていることが必要となる。In order to clarify the technical structures of the first and second embodiments, a film (for example, a metal film of Au, Ag, etc.) having no fine aperture or metal fine scatterer and a non-aperture type When an optical disc in which the super-resolution film of (1) is laminated and reproduced, the signal strength tends to decrease. From these facts, in the above-described first embodiment, which is characterized in that the non-aperture type super-resolution film and the aperture type super-resolution film are combined, the role of the aperture type super-resolution film is the conventional one. Rather than narrowing the beam by forming a minute aperture like the proposal made,
The purpose is to form a micro-aperture below the wavelength to cause electromagnetic interaction. Then, in order to cause the electromagnetic interaction, the stacking order for the beam is important.
When the reproducing beam light strikes the aperture-type super-resolution film first, the non-aperture-type super-resolution effect does not occur, or even if it occurs, it is weak, so that only the aperture-type super-resolution effect acts. Therefore, it is necessary that the non-aperture type super-resolution film 2 is arranged on the beam incident side on the light-transmissive substrate 1, and the aperture-type super-resolution film 3 is laminated thereon.
【００１１】一方、第２の実施例においては、金属微小
散乱体を含む微小散乱体膜６それ自体はビーム径を絞る
効果を持たないため、非開口型の超解像膜２との積層順
は特に制限されるものではなく、どちらが上でも下でも
構わない。
＜実施例＞以下に、本発明の光記録媒体を実施例１、２
として実際に作成してその評価を行ったので、その評価
結果を比較例１〜４と共に説明する。
（実施例１）図１（Ａ）に示すように、凹凸により情報
が記録されたポリカーボネート樹脂よりなる光透過性の
基板１上に、非開口型の超解像膜２としてSi膜をスパッ
タリングで15nmの厚さで形成し、その後、開口型の超解
像膜３としてサーモクロミック膜を積層した。このサー
モクロミック膜は呈色材と顕色材の２成分からなる材料
を使用し、２元蒸着機を用い重量％で略１：２の割合で
260nmの厚さで成膜した。その上にサーモクロミック膜
である開口型の超解像膜３と紫外線硬化樹脂の保護膜５
との混合を防ぐための誘電体膜４としてZnS-SiO2膜をス
パッタリングで20nmの厚さで形成した。その後、、保護
膜５として紫外線硬化樹脂を塗布した。On the other hand, in the second embodiment, since the fine scatterer film 6 including the metal fine scatterer itself does not have the effect of narrowing the beam diameter, the stacking order with the non-aperture type super-resolution film 2 is increased. Is not particularly limited, and either may be above or below. <Example> Hereinafter, the optical recording medium of the present invention will be described in Examples 1 and 2.
Since it was actually created and evaluated, the evaluation results will be described together with Comparative Examples 1 to 4. (Example 1) As shown in FIG. 1A, a Si film was sputtered as a non-aperture type super-resolution film 2 on a light-transmissive substrate 1 made of a polycarbonate resin on which information was recorded by unevenness. It was formed to a thickness of 15 nm, and then a thermochromic film was laminated as an aperture type super-resolution film 3. This thermochromic film uses a material consisting of two components, a coloring material and a developing material, and uses a two-source vapor deposition machine at a weight ratio of about 1: 2.
The film was formed to a thickness of 260 nm. An opening-type super-resolution film 3 which is a thermochromic film and a protective film 5 of an ultraviolet-curing resin are formed on it.
A ZnS—SiO 2 film was formed as the dielectric film 4 to prevent the mixture with the film by sputtering to a thickness of 20 nm. After that, an ultraviolet curable resin was applied as the protective film 5.
【００１２】（実施例２）図１（Ｂ）に示すように、凹
凸により情報が記録されたポリカーボネート樹脂よりな
る光透過性の基板１上に、非開口型の超解像膜２として
Si膜をスパッタリングで15nmの厚さで形成し、その後、
金属微小散乱体を含む微小散乱体膜（超解像膜）６とし
て金属微粒子が分散された誘電体膜（以下、グラニュラ
ー膜とも称す）を積層した。本実施例でのグラニュラー
膜は、SiO2にAg微粒子を分散させた膜を用いた。このグ
ラニュラー膜は、スパッタリングで形成し、SiO2ターゲ
ット上にAgチップを置いたスパッタリングで形成し、Ag
チップの数で微粒子の粒径を約10nmに調整した。この膜
厚は20nmとした。その上に保護膜５として紫外線硬化樹
脂を塗布した。Example 2 As shown in FIG. 1B, a non-aperture type super-resolution film 2 was formed on a light-transmissive substrate 1 made of a polycarbonate resin on which information was recorded by unevenness.
A Si film is formed with a thickness of 15 nm by sputtering, and then
As the fine scatterer film (super-resolution film) 6 containing the metal fine scatterer, a dielectric film (hereinafter also referred to as a granular film) in which fine metal particles were dispersed was laminated. As the granular film in this example, a film in which Ag particles were dispersed in SiO 2 was used. This granular film was formed by sputtering, and the Ag chip was placed on a SiO 2 target to form Ag.
The particle size of the fine particles was adjusted to about 10 nm by adjusting the number of chips. This film thickness was 20 nm. An ultraviolet curable resin was applied as a protective film 5 thereon.
【００１３】（比較例１）ポリカーボネート樹脂よりな
る光透過性の基板１上に、非開口型の超解像膜２として
Si膜をスパッタリングで15nmの厚さで形成し、その上に
紫外線硬化樹脂からなる保護膜５を形成した。
（比較例２）ポリカーボネート樹脂よりなる光透過性の
基板１上に、開口型の超解像膜３としてサーモクロミッ
ク膜を積層し、その上にAl反射膜、紫外線硬化樹脂より
なる保護膜５を順次積層した。上記サーモクロミック膜
は、実施例１と同様に呈色材と顕色材の２成分からなる
材料を使用し、２元蒸着機を用い重量％で略１：２の割
合で260nmの厚さで成膜した。Comparative Example 1 A non-aperture type super-resolution film 2 was formed on a light-transmissive substrate 1 made of polycarbonate resin.
A Si film was formed with a thickness of 15 nm by sputtering, and a protective film 5 made of an ultraviolet curable resin was formed thereon. (Comparative Example 2) A thermochromic film was laminated as an aperture type super-resolution film 3 on a light-transmissive substrate 1 made of a polycarbonate resin, and an Al reflection film and a protective film 5 made of an ultraviolet curable resin were formed thereon. The layers were sequentially laminated. The thermochromic film uses a material composed of two components, a color material and a color developing material, as in Example 1, and a binary vapor deposition machine is used to form a thermochromic film having a thickness of 260 nm at a weight ratio of about 1: 2. A film was formed.
【００１４】（比較例３）光透過性の基板１上に、超解
像効果を示さない膜としてAg膜をスパッタリングで15nm
の厚さで形成し、その後、開口型の超解像膜3としてサ
ーモクロミック膜を積層した。このサーモクロミック膜
は実施例１と同様の方法で成膜した。その上にサーモク
ロミック膜３と紫外線硬化樹脂の保護膜５との混合を防
ぐための誘電体膜４としてZnS-SiO2膜をスパッタリング
で20nmの厚さで形成した後、保護膜５として紫外線硬化
樹脂を塗布した。
（比較例４）光透過性の基板１上に、超解像効果を示さ
ない膜としてAgをスパッタリングで15nmの厚さで形成
し、その後、微小散乱体型の超解像膜として、実施例２
と同様にSiO2にAg微粒子を分散させた膜を20nmの厚さで
積層し、その上に紫外線硬化樹脂からなる保護膜５を形
成した。(Comparative Example 3) An Ag film as a film having no super-resolution effect was formed on a light-transmitting substrate 1 by sputtering to have a thickness of 15 nm.
Then, a thermochromic film was laminated as the aperture-type super-resolution film 3. This thermochromic film was formed by the same method as in Example 1. A ZnS-SiO 2 film having a thickness of 20 nm is formed thereon as a dielectric film 4 for preventing mixing of the thermochromic film 3 and the protective film 5 of an ultraviolet curable resin by sputtering, and then the protective film 5 is ultraviolet cured. The resin was applied. (Comparative Example 4) On a light-transmissive substrate 1, Ag having a thickness of 15 nm was formed as a film having no super-resolution effect by sputtering, and then as a microscatterer type super-resolution film, Example 2 was used.
Similarly to the above, a film in which Ag particles were dispersed in SiO 2 was laminated to a thickness of 20 nm, and a protective film 5 made of an ultraviolet curable resin was formed thereon.
【００１５】図２は実施例１と比較例１、２の光ディス
クにおける再生信号のＣＮＲ（ＣＮ比）のピット長依存
性を示すグラフである。この時の測定は、再生ビーム光
のレーザ波長が635nm、ＮＡが0.6、線速度が6m/sec、再
生ビーム光パワーが４mWの条件で行った。この光学系で
の再生限界は0.27μmであり、通常それ以下の記録ピッ
トの再生は不可能である。このグラフから分かるよう
に、実施例１及び比較例１、２のいずれの場合でも再生
限界以下のピット長の再生信号が確認できる。しかし、
そのＣＮＲは異なり、実施例１では非開口型の超解像膜
のみを用いた比較例１よりもピット長0.2μm において
７dB程度、0.25μmにおいて3dB程度大きな再生信号が得
られており、本発明の実施例１の有効性が確認できた。FIG. 2 is a graph showing the pit length dependence of the CNR (CN ratio) of the reproduced signal on the optical disks of Example 1 and Comparative Examples 1 and 2. The measurement at this time was performed under the conditions that the laser wavelength of the reproduction beam light was 635 nm, the NA was 0.6, the linear velocity was 6 m / sec, and the reproduction beam light power was 4 mW. The reproduction limit of this optical system is 0.27 μm, and it is usually impossible to reproduce recording pits smaller than that. As can be seen from this graph, in both cases of Example 1 and Comparative Examples 1 and 2, a reproduced signal having a pit length equal to or shorter than the reproduction limit can be confirmed. But,
The CNR is different, and in Example 1, a reproduction signal of about 7 dB at a pit length of 0.2 μm and about 3 dB at a pit length of 0.25 μm was obtained as compared with Comparative Example 1 using only a non-aperture type super-resolution film. The effectiveness of Example 1 was confirmed.
【００１６】一方、再生限界以上（0.27μm以上）の長
いピットにおいて、通常の開口型の超解像である比較例
２では実質的に再生ビーム光が絞られているためＣＮＲ
は一定の値以上、例えば50dB程度以上に向上しないが、
非開口型の超解像効果のある実施例１では、ピット長が
再生限界よりも長くなると信号強度が増大している。従
って、実施例１は、比較例１、２よりも優れた特性を有
することが確認できた。図３は実施例１と比較例３のピ
ット長0.26μmにおける再生信号のＣＮＲの再生ビーム
光パワー依存性を示すグラフである。この時の測定条件
は、再生ビーム光の再生パワーを変えて測定している点
以外は上記図２の場合と同様である。ここでは反射膜が
超解像効果を示さないAg膜である比較例３に対し、非開
口型の超解像膜であるSi膜を用いた実施例１では、ＣＮ
Ｒはより大きくなる事が確認できた。On the other hand, in the comparative example 2 which is a normal aperture type super-resolution, the reproduction beam light is substantially narrowed in the long pit which is equal to or more than the reproduction limit (0.27 μm or more).
Does not improve above a certain value, for example, above 50 dB,
In Example 1 having a non-aperture type super-resolution effect, the signal intensity increases when the pit length becomes longer than the reproduction limit. Therefore, it was confirmed that Example 1 had better characteristics than Comparative Examples 1 and 2. FIG. 3 is a graph showing the dependence of the CNR of the reproduction signal on the reproduction beam light power at the pit length of 0.26 μm in Example 1 and Comparative Example 3. The measurement conditions at this time are the same as those in the case of FIG. 2 above except that the reproduction power of the reproduction beam light is changed. Here, in Comparative Example 3 in which the reflective film is an Ag film that does not exhibit a super-resolution effect, in Example 1 in which the Si film that is a non-aperture type super-resolution film is used, CN
It was confirmed that R becomes larger.
【００１７】同様に図４は実施例２と比較例１及び比較
例４のピット長0.26μmにおける再生信号のＣＮＲの再
生ビーム光パワー依存性を示すグラフである。ここでは
単層で超解像効果を示す比較例１、超解像効果を示さな
い膜と微小散乱体型の超解像膜（微小散乱体膜）の組み
合わせである比較例４に対し、超解像効果を示す膜（非
開口型の超解像膜）と微小散乱体型の超解像膜（微小散
乱体膜）の組み合わせである実施例２では、ＣＮＲの増
大が認められ、この第２実施例の特性が良好であること
が確認できた。Similarly, FIG. 4 is a graph showing the dependence of the CNR of the reproduction signal on the reproduction beam light power at the pit length of 0.26 μm in Example 2 and Comparative Examples 1 and 4. In contrast to Comparative Example 1 in which a single layer exhibits a super-resolution effect and Comparative Example 4 in which a film not exhibiting a super-resolution effect and a micro-scatterer type super-resolution film (micro-scatterer film) are combined, In Example 2, which is a combination of a film exhibiting an image effect (a non-aperture type super-resolution film) and a microscatterer type super-resolution film (microscatterer film), an increase in CNR was observed. It was confirmed that the characteristics of the example were good.
【００１８】尚、以上に説明した各実施例は、単に一例
を示したに過ぎず、本発明に利用できる非開口型の超解
像膜、開口型の超解像膜、金属微小散乱体を有する微小
散乱体膜の各材料、膜厚等は上記の実施例に限られるも
のではない。例えば非開口型の超解像膜としては、プラ
ズモン効果を有する材料を用いた膜、エバネッセント効
果を有する材料を用いた膜、他にGe,Mo,W等の材料が挙
げられる。また、開口型の超解像膜には、再生ビームの
スポット内に生じる温度分布を利用し、実効的にビーム
径より小さくし、使用レーザの波長以下の光学的開口を
形成できる超解像膜であれば使用可能であり、例えばサ
ーモクロミック材料膜や、自己収束効果材料（温度変化
により、屈折率が変化する性質を有する各種色素、半導
体、無機化合物）や、Sb膜、フォトクロミック材料膜、
GeSbTe膜等の相変化材料等が挙げられる。更には、金属
微小散乱体を形成する微小散乱体膜としては、非固溶で
ある金属と誘電体の組み合わせ（例えば金属としてはA
u,Cu等、誘電体としてはAl2O3、SiN等）であれば使用可
能であり、また酸化銀などの熱化学反応により可逆的に
金属微粒子が析出する膜でも良い。そして、それぞれの
膜厚は材料に応じて適宜調整されることは勿論である。Each of the embodiments described above is merely an example, and a non-aperture type super-resolution film, an aperture type super-resolution film, and a metal microscatterer which can be used in the present invention are described. The materials, film thicknesses, and the like of the minute scatterer film that it has are not limited to those in the above embodiments. For example, the non-aperture type super-resolution film includes a film using a material having a plasmon effect, a film using a material having an evanescent effect, and other materials such as Ge, Mo, and W. The aperture-type super-resolution film is a super-resolution film that can effectively reduce the beam diameter by using the temperature distribution generated in the spot of the reproduction beam to form an optical aperture that is less than the wavelength of the laser used. If it is possible to use, for example, thermochromic material film, self-focusing effect material (various dyes, semiconductors, inorganic compounds having the property of changing the refractive index due to temperature change), Sb film, photochromic material film,
Examples include phase change materials such as GeSbTe film. Furthermore, as the fine scatterer film forming the metal fine scatterer, a combination of a non-solid solution metal and a dielectric (for example, a metal is A
It is possible to use u, Cu or the like as the dielectric if it is Al 2 O 3 , SiN or the like), or a film in which fine metal particles are reversibly precipitated by a thermochemical reaction such as silver oxide. And, it goes without saying that each film thickness is appropriately adjusted according to the material.
【００１９】[0019]
【発明の効果】以上説明したように、本発明の光記録媒
体によれば、回折限界以下の微小記録ピットの再生信号
のＣＮＲを大幅に向上させることができる。As described above, according to the optical recording medium of the present invention, the CNR of the reproduction signal of the minute recording pits below the diffraction limit can be greatly improved.
【図１】本発明に係る光記録媒体を示す断面図である。FIG. 1 is a sectional view showing an optical recording medium according to the present invention.
【図２】実施例１と比較例１、２の光ディスクにおける
再生信号のＣＮＲ（ＣＮ比）のピット長依存性を示すグ
ラフである。FIG. 2 is a graph showing the pit length dependence of the CNR (CN ratio) of the reproduced signal on the optical disks of Example 1 and Comparative Examples 1 and 2.
【図３】実施例１と比較例３のピット長0.26μmにおけ
る再生信号のＣＮＲの再生ビーム光パワー依存性を示す
グラフである。FIG. 3 is a graph showing the reproduction beam light power dependency of the CNR of the reproduction signal at a pit length of 0.26 μm in Example 1 and Comparative Example 3.
【図４】実施例２と比較例１及び比較例４のピット長0.
26μmにおける再生信号のＣＮＲの再生ビーム光パワー
依存性を示すグラフである。FIG. 4 is a pit length of 0 for Example 2 and Comparative Examples 1 and 4.
It is a graph which shows the reproduction beam light power dependence of CNR of a reproduction signal in 26 micrometers.
１…基板、２…非開口型の超解像膜、３…開口型の超解
像膜、４…誘電体膜、５…保護膜、６…微小散乱体膜、
Ｌ…再生ビーム光。DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Non-aperture type super-resolution film, 3 ... Aperture type super-resolution film, 4 ... Dielectric film, 5 ... Protective film, 6 ... Microscatterer film,
L ... Playback beam light.
───────────────────────────────────────────────────── フロントページの続き (71)出願人 301021533 独立行政法人産業技術総合研究所 東京都千代田区霞が関１−３−１ (72)発明者 野村 昭彦 神奈川県横浜市神奈川区守屋町３丁目12番 地 日本ビクター株式会社内 (72)発明者 菊川 隆 東京都中央区日本橋一丁目13番１号ティー ディーケイ株式会社内 (72)発明者 藤 寛 大阪府大阪市阿倍野区長池町22番22号シャ ープ株式会社内 (72)発明者 富永 淳二 茨城県つくば市東１−１−１ 独立行政法 人産業技術総合研究所つくばセンター内 Ｆターム(参考） 5D029 JB50 MA01 MA04 MA05 MA17 ─────────────────────────────────────────────────── ─── Continued front page (71) Applicant 301021533 National Institute of Advanced Industrial Science and Technology 1-3-1 Kasumigaseki, Chiyoda-ku, Tokyo (72) Inventor Akihiko Nomura 3-12 Moriya-cho, Kanagawa-ku, Yokohama-shi, Kanagawa Local Victor Company of Japan, Ltd. (72) Inventor Takashi Kikukawa 1-13-1, Nihonbashi, Chuo-ku, Tokyo Tea DC Inc. (72) Inventor Hiroshi Fuji 22-22 Nagaike, Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Group Co., Ltd. (72) Inventor Junji Tominaga 1-1-1 Higashi 1-1-1 Tsukuba City, Ibaraki Prefecture Inside the Tsukuba Center, National Institute of Advanced Industrial Science and Technology F-term (reference) 5D029 JB50 MA01 MA04 MA05 MA17
Claims (4)
り信号を読み出すことができるようにした光記録媒体に
おいて、光透過性の基板上に非開口型の超解像膜と開口
型の超解像膜とをこの順に積層したことを特徴とする光
記録媒体。1. A non-aperture-type super-resolution film and an aperture-type super-resolution film on a light-transmissive substrate in an optical recording medium capable of reading a signal by changing the reflectance with respect to a reproduction beam light. An optical recording medium comprising a film and a film laminated in this order.
り信号を読み出すことができるようにした光記録媒体に
おいて、光透過性の基板上に非開口型の超解像膜と金属
微小散乱体を含む微小散乱体膜とを積層されていること
を特徴とする光記録媒体。2. An optical recording medium in which a signal can be read out by a change in reflectance with respect to a reproduction beam light, which includes a non-aperture type super-resolution film and a metal fine scatterer on a light-transmissive substrate. An optical recording medium characterized by being laminated with a fine scatterer film.
ック膜で形成されている事を特徴とする請求項１または
２記載の光記録媒体。3. The optical recording medium according to claim 1, wherein the aperture type super-resolution film is formed of a thermochromic film.
な金属の微粒子を分散させてなることを特徴とする請求
項２または３記載の光記録媒体。4. The optical recording medium according to claim 2, wherein the minute scatterer is formed by dispersing non-solid-solution metal fine particles in a dielectric film.
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| JP2001317177A JP4040280B2 (en) | 2001-10-15 | 2001-10-15 | Optical recording medium |
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|---|---|---|---|
| JP2001317177A JP4040280B2 (en) | 2001-10-15 | 2001-10-15 | Optical recording medium |
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| JP4040280B2 JP4040280B2 (en) | 2008-01-30 |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6961300B2 (en) * | 2001-06-29 | 2005-11-01 | Korea Institute Of Science And Technology | Optical recording medium having first and second super-resolution layers |
| WO2007037070A1 (en) * | 2005-09-29 | 2007-04-05 | Sharp Kabushiki Kaisha | Optical information recording medium and optical information recording medium reproducing device |
| US7556912B2 (en) | 2003-06-06 | 2009-07-07 | Sharp Kabushiki Kaisha | Optical information recording medium, reproducting method using the same, and optical information processing device |
-
2001
- 2001-10-15 JP JP2001317177A patent/JP4040280B2/en not_active Expired - Lifetime
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6961300B2 (en) * | 2001-06-29 | 2005-11-01 | Korea Institute Of Science And Technology | Optical recording medium having first and second super-resolution layers |
| US7556912B2 (en) | 2003-06-06 | 2009-07-07 | Sharp Kabushiki Kaisha | Optical information recording medium, reproducting method using the same, and optical information processing device |
| WO2007037070A1 (en) * | 2005-09-29 | 2007-04-05 | Sharp Kabushiki Kaisha | Optical information recording medium and optical information recording medium reproducing device |
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|---|---|
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