JP2006134365A - Optical recording medium and optical recording method - Google Patents
Optical recording medium and optical recording method Download PDFInfo
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- JP2006134365A JP2006134365A JP2002364871A JP2002364871A JP2006134365A JP 2006134365 A JP2006134365 A JP 2006134365A JP 2002364871 A JP2002364871 A JP 2002364871A JP 2002364871 A JP2002364871 A JP 2002364871A JP 2006134365 A JP2006134365 A JP 2006134365A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/004—Recording, reproducing or erasing methods; Read, write or erase circuits therefor
- G11B7/0045—Recording
- G11B7/00455—Recording involving reflectivity, absorption or colour changes
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/2403—Layers; Shape, structure or physical properties thereof
- G11B7/24035—Recording layers
- G11B7/24038—Multiple laminated recording layers
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
- G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
- G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
- G11B7/252—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers
- G11B7/254—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of layers other than recording layers of protective topcoat layers
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B2007/0003—Recording, reproducing or erasing systems characterised by the structure or type of the carrier
- G11B2007/0009—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage
- G11B2007/0013—Recording, reproducing or erasing systems characterised by the structure or type of the carrier for carriers having data stored in three dimensions, e.g. volume storage for carriers having multiple discrete layers
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- Physics & Mathematics (AREA)
- Mathematical Physics (AREA)
- Theoretical Computer Science (AREA)
- Crystallography & Structural Chemistry (AREA)
- Optical Record Carriers And Manufacture Thereof (AREA)
- Optical Recording Or Reproduction (AREA)
Abstract
Description
【0001】
【発明の属する技術分野】
本発明は、光ディスクあるいは光カードなど、情報を光学的に記録もしくは再生する光記録媒体、および、この光記録媒体へ情報を記憶する光記録方法に関するものである。
【0002】
【従来の技術】
光ディスクに代表される光情報処理装置は情報の記録、保管手段として広く利用されてきている。昨今の高度情報化社会の進展により、光情報処理装置は、高速化や高密度化する必要となってきている。一般的に光情報処理装置では、光の吸収の結果生じる熱により情報を記録する、いわゆるヒートモードの記録方式が用いられている。しかしながら、このヒートモード記録方式は、材料の発熱、冷却現象を利用しているために、情報の記録時間に限界がある。また、熱の拡散により記録密度にも限界があった。
【0003】
これに対し、熱を介さず光により直接記録材料を変化させる、いわゆるフォトンモード記録方式がある(例えば、非特許文献1参照)。以下、図11および図12を用いて従来のフォトンモード光記録方式について説明する。図11において70は基板、71は2-(1-octyl-2-methyl-3-indolyl)-3-(2,3,5-trimethyl-3-thyenyl)maleic anhydrideからなるフォトクロミックな記録膜であり、72は反射膜である。またL0は記録や再生に用いる集光された光を示している。
【0004】
記録膜71は図12のような吸収率の分光特性を示す2つの状態Aおよび状態Bを持つ感光材料を使用している。状態Aの記録膜71に波長λ1(450nm近傍)の光を照射すると、記録膜71の吸収率の分光特性は状態Bに変化し、状態Bの記録膜71に波長λ2(600nm近傍)の光を照射すると、記録膜71の吸収率の分光特性は状態Bに変化するフォトクロミックな特性をもつ。この状態の変化を利用して、情報の記録を行なう。
【0005】
【非特許文献1】
Jpn. J. Appl. Phys. Vol.34 (1995) pp.6439-6443
【0006】
【発明が解決しようとする課題】
このようなフォトンモードの記録は、光により感光させて記録するため、保存環境での通常の光や、装置内迷光などの記録光以外の光でも感光され、記録された情報が消失してしまうという問題がある。
【0007】
これは、フォトンモードの記録が光の照射量に比例するためで、たとえ比較的弱い光でも、長時間照射された場合、その変化が蓄積され情報が消失してしまうことになる。このため保存には、暗所を選ぶとか、遮光したケースで保管するなどの対策が必要であった。また装置への装着も暗所で行なう必要があり、装置内の迷光も十分に減らす必要があった。
【0008】
本発明はこのような課題を解決するためになされたものであり、保存環境での通常の光や装置内迷光などの記録光以外の光により、記録情報が消去されることがない光記録媒体を得ること、この光記録媒体へ情報を記録する光記録方法をえることを目的とする。
【0009】
【課題を解決するための手段】
本発明の光記録媒体は、レーザ光を照射することにより情報を記録する光記録媒体で、フォトンモードの記録材料と、前記記録材料を変化させる波長の光を遮光し、前記レーザ光の波長λ1の光を透過する波長選択吸収材料とを含み、前記記録材料はλ1/n(nは2以上の整数)の光により変化する特性を有し、前記記録材料は前記記録材料を透過した前記レーザ光をn光子吸収し変化することを特徴とする。
【0010】
また、前記記録材料が基板の上に形成されており、前記波長選択吸収材料が前記基板であることを特徴とする。
【0011】
また、前記記録材料を挟み前記波長選択材料の反対側に位置する遮光材料を有することを特徴とする。
【0012】
また、前記遮光材料が反射膜であることを特徴とする。
【0013】
また、前記記録材料がフォトクロミック材料であることを特徴とする。
【0014】
また、前記記録材料がジアリールエテン系材料、スピロピラン系材料、フルギド系材料、アゾ系材料のいずれかを含むことを特徴とする。
【0015】
また、前記記録材料が追記型材料であることを特徴とする。
【0016】
また、光退色性を有する色素、光発色性を有する色素、フォトポリマのいずれかを含むことを特徴とする。
【0017】
また、前記記録と前記波長選択吸収材料が透光性材料にそれぞれ隣接していることを特徴とする。
【0018】
また、前記記録材料を汚れもしくは機械的衝撃から保護する保護層を有し、前記波長選択吸収材料が前記保護層であることを特徴とする。
【0019】
また、前記記録材料を挟み前記波長選択材料の反対側に位置し、前記記録材料を変化させる波長の光を遮光し、波長λ1の光を透過する第2の波長選択吸収材料を有することを特徴とする。
【0020】
また、前記記録材料が中間層を挟み複数層有すること有することを特徴とする。
【0021】
また、前記記録材料が波長λ1の光に対して半透明であることを特徴とする。
【0022】
また、前記記録材料が波長λ1の光に対して透明であることを特徴とする。
【0023】
また、前記中間層が前記記録材料を変化させる波長を吸収することを特徴とする。
【0024】
また、端部が遮光材量で覆われていることを特徴とする。
【0025】
本発明の光記録方法は、レーザ光を照射することにより情報を光記録媒体に記録する光記録方法で、前記光記録媒体がフォトンモードの記録材料と、前記記録材料を変化させる波長の光を遮光し、前記レーザ光の波長λ1の光を透過する波長選択吸収材料を含み、前記記録材料がλ1/n(nは2以上の整数)の光により変化する特性を有し、前記記録材料を前記記録材料を透過した前記レーザ光をn光子吸収させ情報を記録することを特徴とする。
【0026】
本発明の光記録方法は、レーザ光を照射することにより情報を光記録媒体に記録する光記録方法で、前記光記録媒体が中間層を挟み複数のフォトンモードの記録材料を有し、前記記録材料を変化させる波長の光を遮光し、前記レーザ光の波長λ1の光を透過する波長選択吸収材料を含み、前記記録材料がλ1/n(nは2以上の整数)の光により変化する特性を有し、さらに前記記録材料は前記λ1の光に対して半透明であり、前記記録材料を前記記録材料を透過した前記レーザ光をn光子吸収させ情報を記録することを特徴とする。
【0027】
本発明の光記録方法は、レーザ光を照射することにより情報を光記録媒体に記録する光記録方法で、前記光記録媒体が中間層を挟み複数のフォトンモードの記録材料を有し、前記記録材料を変化させる波長の光を遮光し、前記レーザ光の波長λ1の光を透過する波長選択吸収材料を含み、前記記録材料がλ1/n(nは2以上の整数)の光により変化する特性を有し、さらに前記記録材料は前記λ1の光に対して透明であり、前記記録材料を前記記録材料を透過した前記レーザ光をn光子吸収させ情報を記録することを特徴とする。
【0028】
【発明の実施の形態】
(実施の形態1)
図1は実施の形態1の光記録媒体の一例を示す断面図である。701は基板、711はフォトンモードの記録材料からなる記録膜である。また72は記録膜711を透過した光を反射する反射膜である。基板701は、記録膜711を感光する波長域の光を吸収する波長選択吸収材料を用いている。
【0029】
以下、その動作について説明する。図中のL0は記録再生を行なうための記録膜711上に集光されたレーザ光である。レーザ光L0は基板701で吸収されず、その1/2の波長の光は記録膜711を感光するような波長λの光を使用する。この様な波長λのレーザ光L0は、基板701を透過し記録膜711に入射する。前述のように、基板701を透過する光は記録膜711を感光しないが、記録膜近傍では集光しているため光強度が大きくなり、適当な強度の光を照射すれば2光子吸収が発生し、記録膜711を感光する。再生は2光子吸収が発生しない範囲の強度で記録膜711を照射し、記録状態の屈折率の違いによる反射率や回折率の違いにより信号を検出する。
【0030】
本実施の形態の光記録媒体では、保存時の室内光や装置内迷光のようなレーザ光L0以外の不要光によって記録した情報が消失することがない。つまり、このような不要光で、記録膜711を感光する波長の光は基板701で吸収され記録膜711には入射しない。また基板と反対から入射した不要光は反射膜72により遮光されるため、記録膜711を感光することはない。ここでは、2光子吸収による情報の記録する場合について説明したがこの限りではなく、3光子吸収など多光子吸収による記録の場合も有効である。なおこの場合は、多光子吸収にたいして等価的な波長(n次吸収の場合は1/nの波長)に対して、記録膜711が感光される必要がある。
【0031】
さらに具体的な構成として、記録膜711のフォトンモード記録材料として、フォトクロミック材料を用いた場合にいて説明する。ここでは、フォトクロミック材料としてジアリールエテン系である1,2-cis-1,2-bis(2,4,5-trimethyl-3-thienyl)etheneを例に説明する。
【0032】
図2はこのフォトクロミック材料の吸収率の分光特性である。図2に示すように、フォトクロミック材料は吸収率の分光特性を示す2つの状態Aおよび状態Bを持ち、照射する光の波長により一方の状態から他方の状態へ分光特性が変化する。状態Aから状態Bへの変化は波長400nm近傍の光を照射することにより、状態Bから状態Aへの変化は波長500nm近傍の光を照射することにより起きる。記録は波長λ1(780nm)の波長のレーザを用いる。レーザはパルス状に駆動し平均強度を小さく保ちながら集光点での光強度を大きくする。このことにより、フォトクロミック材料内で2光子吸収が発生し、波長390nmを照射した場合と同じ状態となり、状態Aから状態Bへ変化する。また、消去は波長λ2(1000nm)の波長のレーザを用いる。この場合もレーザはパルス状に駆動し、2光子吸収を発生させ状態Bから状態Aへ変化させる。再生は波長λ1もしくは波長λ2のレーザを連続光で照射し、二光子吸収がおこらない範囲の光強度で信号を検出する。基板701は図2で示すように、フォトクロミック材料が感光する範囲の光を吸収し、記録光(波長:λ1)および消去光(波長:λ2)を透過する材料であればよく、適当な色素を混入した樹脂などを用いる。
【0033】
以上の様に、本発明によれば、保存環境での通常の光や装置内迷光などの記録光以外の光により、記録情報が消去されることもなく、信頼性の高いフォトンモードの光記録媒体が実現できる。
【0034】
なお、ここでは、記録膜711を構成する記録材料としてジアリールエテン系のフォトクロミック材料を例に説明したがその限りではなく、これ以外のジアリールエテン系材料、スピロピラン系材料、フルギド系材料、アゾ系材料などの一般のフォトクロミック材料でもよい。またフォトクロミック材料に限らずフォトンモードの記録材料であれば同じような効果がある。また、ここでは書き換え可能な光記録媒体について例に説明したが、一度しか記録しない追記型のフォトンモードの記録材料(感光材料)を用いた記録膜711を有する光記録媒体でも同じ効果があり、この場合は消去光を用いる必要がない。この記録材料の一例として光退色性や光発色性を有する色素、光により重合する樹脂、いわゆるフォトポリマ(例えばアクリル系光硬化樹脂など)が挙げられる。
【0035】
(実施の形態2)
図3は実施の形態2の光記録媒体の一例を示す断面図である。実施の形態1の光記録媒体において、記録膜711に情報を記録する場合、基板701と記録膜711の境界付近では基板701でも2光子吸収され記録膜711の記録に十分な光量が得られない場合がある。
【0036】
この場合、図3で示すように基板701と記録膜711の間に透光性材料431を配置して解決できる。透光性材料431は記録光(消去可能な光記録媒体の場合は消去光も)とその1/2の波長の光に対して透明で集光点付近でも2光子吸収がおこらない。このため、記録膜711へ光が入射することができ、効率よく記録可能となる。
【0037】
(実施の形態3)
光記録媒体は記録密度を増加するために高いNAのレンズにより記録再生が行われる場合がある。この場合、基板を透過する構成の光記録媒体では、記録媒体の傾きにより発生する波面収差が問題となる。このため、汚れや機械的な衝撃から記録膜を保護するために設けられた保護層側から記録再生する光記録媒体が用いられることがある。このような場合でも本発明は効果がある。
【0038】
図4は実施の形態3の光記録媒体の一例を示す断面図である。702は基板、72は反射膜、記録膜711は実施の形態1で説明したフォトンモードの記録材料からなる記録膜である。741は透光性材料431により接着されている保護層である。保護層741は実施の形態1で説明した基板701と同じ波長選択吸収材料からなる。
【0039】
このような構成により、実施の形態1と同様の原理により保護層側から記録再生する場合であっても、保存環境での通常の光や装置内迷光などの記録光以外の光により、記録情報が消去されることがない、信頼性の高いフォトンモードの光記録媒体が実現できる。
【0040】
(実施の形態4)
記録再生装置によっては、記録材料を透過する光を直接検出する透過型の光記録媒体が必要となる。この場合、これまで説明してきたような反射膜による遮光を利用することができない。このような場合でも本発明は効果がある。
【0041】
図5は実施の形態4の光記録媒体の一例を示す断面図である。実施の形態1で説明した記録膜711を同じく実施の形態1で説明した基板701と基板701と同じ波長選択吸収材料からなる基板703で挟んだ構造となっている。基板703は基板701と同じ波長選択吸収材料で形成されているので、記録光(消去する場合は消去光、再生する場合再生光)は透過するが、記録膜711を感光する波長域の光は透過しない。
【0042】
このような構成により、実施の形態1と同様の原理により記録膜711を構成する記録材料を透過する光を直接検出する透過型の光記録媒体であっても、保存環境での通常の光や装置内迷光などの記録光以外の光により、記録情報が消去されることがない、信頼性の高いフォトンモードの光記録媒体が実現できる。
【0043】
(実施の形態5)
本発明は、大容量化ために記録膜を複数層持ついわゆる多層光記録媒体においても有効である。
【0044】
ここでは、図6は実施の形態5の光記録媒体の一例を示す断面図である。実施の形態3で説明した記録膜711を複数層の記録膜とこれらに挟まれた中間層73で置き換えたものである。中間層73は記録光に対して(消去可能な光記録媒体の場合は消去光に対しても)透明なものを使用する。記録膜712はこれまでに説明した記録膜711とおなじ性質をも持つものを用いる。また、記録膜712は記録光に対して(消去可能な光記録媒体の場合は消去光に対しても)半透明なものを使用すれば良いが、記録光に対して(消去可能な光記録媒体の場合は消去光に対しても)透明なものを使用すれば、下層を記録する場合でも光量が減少することなく、効率よく記録が可能となる。実施の形態1で説明したジアリールエテンはこのような条件を満足するものの一例として挙げることができる。
【0045】
また、記録膜712が蛍光を発し、その蛍光により他の記録膜を感光する場合は、中間層73に保護層741とおなじ波長選択吸収材料もしくは同等の性質をもつ波長選択吸収材料を用いることが望ましい。
【0046】
このような構成により、実施の形態1で説明したと同様の原理により、高容量の多層光記録媒体光記録媒体であっても、保存環境での通常の光や装置内迷光などの記録光以外の光により、記録情報が消去されることがない、信頼性の高いフォトンモードの光記録媒体が実現できる。
【0047】
なお、ここでは実施の形態3の記録膜711を複数の記録膜712と中間層73に置き換えた構造を例にとり説明したが、この限りではなく、実施の形態1の記録膜711を複数の記録膜712と中間層73に置き換えた構造(図7)、実施の形態2の記録膜711を複数の記録膜712と中間層73に置き換えた構造(図8)、実施の形態4の記録膜711を複数の記録膜712と中間層73に置き換えた構造(図9)でも同様の効果がある。
【0048】
(実施の形態6)
図10は実施の形態6の光記録媒体の一例を示す断面図である。光記録媒体32は実施の形態1から5で説明した光記録媒体で、この光記録媒体32の端部を遮光材料46で覆っている。遮光材料46を用いることにより、光記録媒体32端部よりの露光を防ぐことができ、より信頼性の高いフォトンモードの記録媒体が実現できる。
【0049】
【発明の効果】
以上説明したように、本発明によれば、保存環境での通常の光や装置内迷光などの記録光以外の光により、記録情報が消去されることがない、信頼性の高いフォトンモードの光記録媒体が実現できる。
【図面の簡単な説明】
【図1】実施の形態1の光記録媒体の一例を示す断面図
【図2】実施の形態1の光記録媒体の記録膜の吸収率の分光特性を表す図
【図3】実施の形態2の光記録媒体の一例を示す断面図
【図4】実施の形態3の光記録媒体の一例を示す断面図
【図5】実施の形態4の光記録媒体の一例を示す断面図
【図6】実施の形態5の光記録媒体の一例を示す断面図
【図7】実施の形態6の光記録媒体の一例を示す断面図
【図8】実施の形態6の光記録媒体の一例を示す断面図
【図9】実施の形態6の光記録媒体の一例を示す断面図
【図10】実施の形態7の光記録媒体の一例を示す断面図
【図11】従来の光記録媒体を示す断面図
【図12】従来の光記録媒体に使用される記録膜の吸収率の分光特性を表す図
【符号の説明】
70,701,702,703 基板
71,711,712 記録膜
72 反射膜
73 中間層
431 透光性材料
741 保護層
32 光記録媒体
46 遮光材料[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an optical recording medium for optically recording or reproducing information, such as an optical disk or an optical card, and an optical recording method for storing information in the optical recording medium.
[0002]
[Prior art]
Optical information processing apparatuses typified by optical disks have been widely used as information recording and storage means. With the recent progress of an advanced information society, it is necessary to increase the speed and density of optical information processing apparatuses. In general, an optical information processing apparatus employs a so-called heat mode recording method in which information is recorded by heat generated as a result of light absorption. However, this heat mode recording method uses the heat generation and cooling phenomenon of the material, so that there is a limit to the information recording time. In addition, the recording density is limited due to thermal diffusion.
[0003]
On the other hand, there is a so-called photon mode recording method in which the recording material is directly changed by light without using heat (for example, see Non-Patent Document 1). Hereinafter, a conventional photon mode optical recording method will be described with reference to FIGS. 11 and 12. FIG. In FIG. 11, 70 is a substrate, and 71 is a photochromic recording film made of 2- (1-octyl-2-methyl-3-indolyl) -3- (2,3,5-trimethyl-3-thyenyl) maleic anhydride. 72 are reflective films. L0 indicates the condensed light used for recording and reproduction.
[0004]
The recording film 71 uses a photosensitive material having two states A and B showing the spectral characteristics of the absorptance as shown in FIG. When the recording film 71 in the state A is irradiated with light having a wavelength λ1 (near 450 nm), the spectral characteristic of the absorptance of the recording film 71 is changed to the state B, and the recording film 71 in the state B has light having a wavelength λ2 (near 600 nm). , The spectral characteristic of the absorptance of the recording film 71 has a photochromic characteristic that changes to the state B. Information is recorded by utilizing the change in the state.
[0005]
[Non-Patent Document 1]
Jpn. J. Appl. Phys. Vol.34 (1995) pp.6439-6443
[0006]
[Problems to be solved by the invention]
Since such photon mode recording is performed by exposure to light, it is exposed to light other than recording light such as normal light in the storage environment and stray light in the apparatus, and the recorded information is lost. There is a problem.
[0007]
This is because the recording in the photon mode is proportional to the amount of light irradiation, and even if the light is relatively weak, the change is accumulated and information is lost when it is irradiated for a long time. For this reason, it was necessary to take measures such as selecting a dark place or storing it in a light-shielded case. In addition, it is necessary to mount the apparatus in a dark place, and it is necessary to sufficiently reduce stray light in the apparatus.
[0008]
The present invention has been made to solve such a problem, and an optical recording medium in which recorded information is not erased by light other than recording light such as normal light in a storage environment or stray light in the apparatus. And an optical recording method for recording information on the optical recording medium.
[0009]
[Means for Solving the Problems]
The optical recording medium of the present invention is an optical recording medium that records information by irradiating a laser beam. The optical recording medium shields a photon-mode recording material and light having a wavelength that changes the recording material, and the wavelength λ1 of the laser light. The wavelength-selective absorbing material that transmits the light of the recording material, the recording material has a characteristic that changes with light of λ1 / n (n is an integer of 2 or more), and the recording material is transmitted through the recording material It is characterized by changing light by absorbing n photons.
[0010]
Further, the recording material is formed on a substrate, and the wavelength selective absorption material is the substrate.
[0011]
The recording material further includes a light shielding material located on the opposite side of the wavelength selection material.
[0012]
The light-shielding material is a reflective film.
[0013]
The recording material is a photochromic material.
[0014]
Further, the recording material includes any of a diarylethene material, a spiropyran material, a fulgide material, and an azo material.
[0015]
Further, the recording material is a write-once material.
[0016]
Further, it includes any one of a dye having a photobleaching property, a dye having a photochromic property, and a photopolymer.
[0017]
Further, the recording and the wavelength selective absorption material are respectively adjacent to the translucent material.
[0018]
The recording material further includes a protective layer that protects the recording material from dirt or mechanical impact, and the wavelength selective absorption material is the protective layer.
[0019]
And a second wavelength-selective absorption material that is located on the opposite side of the wavelength-selective material with the recording material interposed therebetween, shields light of a wavelength that changes the recording material, and transmits light of wavelength λ1. And
[0020]
The recording material may have a plurality of layers with an intermediate layer interposed therebetween.
[0021]
Further, the recording material is translucent to light having a wavelength λ1.
[0022]
The recording material is transparent to light having a wavelength λ1.
[0023]
Further, the intermediate layer absorbs a wavelength that changes the recording material.
[0024]
Further, the end portion is covered with a light shielding material amount.
[0025]
The optical recording method of the present invention is an optical recording method in which information is recorded on an optical recording medium by irradiating a laser beam. The optical recording medium is a photon mode recording material, and light having a wavelength that changes the recording material. Including a wavelength-selective absorbing material that shields light and transmits light of wavelength λ1 of the laser light, and the recording material has a characteristic that changes with light of λ1 / n (n is an integer of 2 or more), The laser beam transmitted through the recording material is absorbed by n photons to record information.
[0026]
The optical recording method of the present invention is an optical recording method for recording information on an optical recording medium by irradiating a laser beam, the optical recording medium having a plurality of photon mode recording materials with an intermediate layer interposed therebetween, and the recording A characteristic that includes a wavelength selective absorption material that blocks light of a wavelength that changes the material and transmits light of wavelength λ1 of the laser light, and the recording material is changed by light of λ1 / n (n is an integer of 2 or more) Further, the recording material is translucent to the light of λ1, and the recording material absorbs the laser light transmitted through the recording material and records information by n-photon absorption.
[0027]
The optical recording method of the present invention is an optical recording method for recording information on an optical recording medium by irradiating a laser beam, the optical recording medium having a plurality of photon mode recording materials with an intermediate layer interposed therebetween, and the recording A characteristic that includes a wavelength selective absorption material that blocks light of a wavelength that changes the material and transmits light of wavelength λ1 of the laser light, and the recording material is changed by light of λ1 / n (n is an integer of 2 or more) Further, the recording material is transparent to the light of λ1, and the recording material records information by absorbing the laser light transmitted through the recording material by n photons.
[0028]
DETAILED DESCRIPTION OF THE INVENTION
(Embodiment 1)
FIG. 1 is a cross-sectional view showing an example of the optical recording medium according to the first embodiment. Reference numeral 701 denotes a substrate, and reference numeral 711 denotes a recording film made of a photon mode recording material. Reference numeral 72 denotes a reflection film that reflects light transmitted through the recording film 711. The substrate 701 uses a wavelength selective absorption material that absorbs light in a wavelength region that sensitizes the recording film 711.
[0029]
The operation will be described below. In the figure, L0 is a laser beam condensed on the recording film 711 for recording and reproduction. The laser light L0 is not absorbed by the substrate 701, and light having a wavelength λ that sensitizes the recording film 711 is used as light having a half wavelength. Such laser light L 0 having a wavelength λ passes through the substrate 701 and enters the recording film 711. As described above, the light transmitted through the substrate 701 does not sensitize the recording film 711, but the light intensity increases because the light is collected in the vicinity of the recording film, and two-photon absorption occurs when light of an appropriate intensity is irradiated. Then, the recording film 711 is exposed. In reproduction, the recording film 711 is irradiated with an intensity within a range where two-photon absorption does not occur, and a signal is detected based on a difference in reflectance and diffraction due to a difference in refractive index in a recording state.
[0030]
In the optical recording medium of the present embodiment, recorded information is not lost by unnecessary light other than the laser light L0 such as room light during storage or stray light in the apparatus. That is, the light having such a wavelength that sensitizes the recording film 711 is absorbed by the substrate 701 and does not enter the recording film 711. Further, since unnecessary light incident from the opposite side of the substrate is shielded by the reflective film 72, the recording film 711 is not exposed. Although the case of recording information by two-photon absorption has been described here, the present invention is not limited to this, and the case of recording by multi-photon absorption such as three-photon absorption is also effective. In this case, the recording film 711 needs to be exposed to a wavelength equivalent to multiphoton absorption (1 / n wavelength in the case of n-order absorption).
[0031]
As a more specific configuration, a case where a photochromic material is used as the photon mode recording material of the recording film 711 will be described. Here, a diarylethene-based 1,2-cis-1,2-bis (2,4,5-trimethyl-3-thienyl) ethene will be described as an example of the photochromic material.
[0032]
FIG. 2 shows the spectral characteristics of the absorptance of this photochromic material. As shown in FIG. 2, the photochromic material has two states A and B showing the spectral characteristics of the absorptance, and the spectral characteristics change from one state to the other depending on the wavelength of the light to be irradiated. The change from the state A to the state B is caused by irradiating light with a wavelength near 400 nm, and the change from the state B to the state A is caused by irradiating light with a wavelength near 500 nm. For recording, a laser having a wavelength of λ 1 (780 nm) is used. The laser is driven in pulses to increase the light intensity at the focal point while keeping the average intensity small. As a result, two-photon absorption occurs in the photochromic material, and the state is the same as when the wavelength of 390 nm is irradiated, and the state A changes to the state B. For erasing, a laser having a wavelength of λ 2 (1000 nm) is used. In this case as well, the laser is driven in a pulsed manner to generate two-photon absorption and change from state B to state A. For reproduction, a laser with wavelength λ 1 or wavelength λ 2 is irradiated with continuous light, and a signal is detected with a light intensity within a range where two-photon absorption does not occur. As shown in FIG. 2, the substrate 701 may be any material that absorbs light in a range where the photochromic material is exposed and transmits recording light (wavelength: λ 1 ) and erasing light (wavelength: λ 2 ). A resin mixed with a dye is used.
[0033]
As described above, according to the present invention, the recording information is not erased by light other than recording light such as normal light in the storage environment or stray light in the apparatus, and the photon mode optical recording with high reliability is achieved. A medium can be realized.
[0034]
Here, a diarylethene-based photochromic material has been described as an example of a recording material constituting the recording film 711. However, the present invention is not limited thereto, and other diarylethene-based materials, spiropyran-based materials, fulgide-based materials, azo-based materials, and the like are used. A general photochromic material may be used. In addition to the photochromic material, a photon mode recording material has the same effect. Further, here, the rewritable optical recording medium has been described as an example, but the same effect can be obtained by an optical recording medium having a recording film 711 using a write-once type photon mode recording material (photosensitive material) that is recorded only once. In this case, it is not necessary to use erasing light. As an example of this recording material, a dye having photobleaching property and photochromic property, a resin that is polymerized by light, a so-called photopolymer (for example, an acrylic photo-curing resin, etc.) can be mentioned.
[0035]
(Embodiment 2)
FIG. 3 is a sectional view showing an example of the optical recording medium according to the second embodiment. In the optical recording medium of
[0036]
In this case, as shown in FIG. 3, it can be solved by arranging a light-transmitting material 431 between the substrate 701 and the recording film 711. The translucent material 431 is transparent to recording light (and erasing light in the case of an erasable optical recording medium) and light having a wavelength half that of the recording light, and does not absorb two photons even near the focal point. For this reason, light can enter the recording film 711 and recording can be performed efficiently.
[0037]
(Embodiment 3)
An optical recording medium may be recorded and reproduced by a lens with a high NA in order to increase the recording density. In this case, in the optical recording medium configured to transmit through the substrate, wavefront aberration caused by the inclination of the recording medium becomes a problem. For this reason, an optical recording medium for recording / reproducing may be used from the side of the protective layer provided to protect the recording film from dirt and mechanical shock. Even in such a case, the present invention is effective.
[0038]
FIG. 4 is a cross-sectional view showing an example of the optical recording medium according to the third embodiment. Reference numeral 702 denotes a substrate, 72 denotes a reflective film, and the recording film 711 is a recording film made of the photon mode recording material described in the first embodiment. Reference numeral 741 denotes a protective layer bonded with a light-transmitting material 431. The protective layer 741 is made of the same wavelength selective absorption material as that of the substrate 701 described in
[0039]
With such a configuration, even when recording / reproduction is performed from the protective layer side according to the same principle as in the first embodiment, recording information is recorded by light other than recording light such as normal light in a storage environment or stray light in the apparatus. A highly reliable photon mode optical recording medium can be realized.
[0040]
(Embodiment 4)
Depending on the recording / reproducing apparatus, a transmission type optical recording medium that directly detects light transmitted through the recording material is required. In this case, the light shielding by the reflective film as described so far cannot be used. Even in such a case, the present invention is effective.
[0041]
FIG. 5 is a cross-sectional view showing an example of an optical recording medium according to the fourth embodiment. The recording film 711 described in
[0042]
With such a configuration, even in a transmissive optical recording medium that directly detects light transmitted through the recording material constituting the recording film 711 based on the same principle as in the first embodiment, normal light in a storage environment or A highly reliable photon mode optical recording medium in which recorded information is not erased by light other than recording light such as in-device stray light can be realized.
[0043]
(Embodiment 5)
The present invention is also effective in a so-called multilayer optical recording medium having a plurality of recording films in order to increase the capacity.
[0044]
Here, FIG. 6 is a cross-sectional view showing an example of the optical recording medium of the fifth embodiment. The recording film 711 described in the third embodiment is replaced with a plurality of recording films and an intermediate layer 73 sandwiched between them. The intermediate layer 73 is transparent to the recording light (and also to the erasing light in the case of an erasable optical recording medium). The recording film 712 has the same properties as the recording film 711 described so far. The recording film 712 may be a translucent film for recording light (and for erasable light in the case of an erasable optical recording medium). If a transparent medium (with respect to erasing light in the case of a medium) is used, even when the lower layer is recorded, recording can be performed efficiently without reducing the amount of light. The diarylethene described in the first embodiment can be given as an example that satisfies such conditions.
[0045]
When the recording film 712 emits fluorescence and other recording films are exposed to the fluorescence, the same wavelength selective absorbing material as that of the protective layer 741 or a wavelength selective absorbing material having the same properties is used for the intermediate layer 73. desirable.
[0046]
With such a configuration, even with a high-capacity multilayer optical recording medium optical recording medium based on the same principle as described in the first embodiment, other than recording light such as normal light in the storage environment and stray light in the apparatus Therefore, it is possible to realize a highly reliable photon mode optical recording medium in which recorded information is not erased by this light.
[0047]
Here, the structure in which the recording film 711 according to the third embodiment is replaced with a plurality of recording films 712 and the intermediate layer 73 has been described as an example. However, the present invention is not limited to this, and the recording film 711 according to the first embodiment has a plurality of recording films. A structure in which the film 712 and the intermediate layer 73 are replaced (FIG. 7), a structure in which the recording film 711 in the second embodiment is replaced with a plurality of recording films 712 and the intermediate layer 73 (FIG. 8), and a recording film 711 in the fourth embodiment. The same effect can be obtained by a structure (FIG. 9) in which is replaced with a plurality of recording films 712 and the intermediate layer 73.
[0048]
(Embodiment 6)
FIG. 10 is a sectional view showing an example of the optical recording medium according to the sixth embodiment. The optical recording medium 32 is the optical recording medium described in the first to fifth embodiments, and the end of the optical recording medium 32 is covered with a light shielding material 46. By using the light shielding material 46, exposure from the end of the optical recording medium 32 can be prevented, and a more reliable photon mode recording medium can be realized.
[0049]
【The invention's effect】
As described above, according to the present invention, highly reliable photon mode light in which recorded information is not erased by light other than recording light such as normal light in a storage environment or stray light in the apparatus. A recording medium can be realized.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of an optical recording medium according to a first embodiment. FIG. 2 is a diagram showing spectral characteristics of the absorption rate of a recording film of the optical recording medium according to the first embodiment. FIG. 4 is a cross-sectional view showing an example of the optical recording medium of Embodiment 3. FIG. 5 is a cross-sectional view showing an example of the optical recording medium of Embodiment 3. FIG. FIG. 7 is a cross-sectional view showing an example of an optical recording medium according to a fifth embodiment. FIG. 7 is a cross-sectional view showing an example of an optical recording medium according to a sixth embodiment. 9 is a cross-sectional view showing an example of an optical recording medium according to Embodiment 6. FIG. 10 is a cross-sectional view showing an example of an optical recording medium according to
70, 701, 702, 703 Substrate 71, 711, 712 Recording film 72 Reflecting film 73 Intermediate layer 431 Translucent material 741 Protective layer 32 Optical recording medium 46 Light shielding material
Claims (19)
フォトンモードの記録材料と、
前記記録材料を変化させる波長の光を遮光し、前記レーザ光の波長λ1の光を透過する波長選択吸収材料とを含み、
前記記録材料はλ1/n(nは2以上の整数)の光により変化する特性を有し、
前記記録材料は前記記録材料を透過した前記レーザ光をn光子吸収し変化することを特徴とする光記録媒体。An optical recording medium that records information by irradiating a laser beam.
Photon mode recording material,
A wavelength selective absorption material that shields light of a wavelength that changes the recording material and transmits light of wavelength λ1 of the laser light,
The recording material has a characteristic that changes with light of λ1 / n (n is an integer of 2 or more),
An optical recording medium, wherein the recording material changes by absorbing n photons of the laser light transmitted through the recording material.
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