JPH07105063B2 - Optical information recording medium - Google Patents
Optical information recording mediumInfo
- Publication number
- JPH07105063B2 JPH07105063B2 JP63227015A JP22701588A JPH07105063B2 JP H07105063 B2 JPH07105063 B2 JP H07105063B2 JP 63227015 A JP63227015 A JP 63227015A JP 22701588 A JP22701588 A JP 22701588A JP H07105063 B2 JPH07105063 B2 JP H07105063B2
- Authority
- JP
- Japan
- Prior art keywords
- recording
- change
- thin film
- reflected light
- light
- 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.)
- Expired - Lifetime
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- Thermal Transfer Or Thermal Recording In General (AREA)
- Optical Record Carriers And Manufacture Thereof (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 本発明は、光・熱等を用いて高速かつ高密度に情報を記
録再生する光学的情報記録媒体に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium that records and reproduces information at high speed and high density by using light, heat and the like.
従来の技術 レーザー光をレンズ系によって収束させると直径がその
光の波長のオーダーの小さな光スポットを作ることがで
きる。したがって小さい出力の光源からでも単位面積あ
たりのエネルギー密度の高い光スポットを作ることが可
能である。これを情報の記録・再生に利用したものが光
学的情報記録媒体である。以下、「光記録媒体」あるい
は単に「媒体」と記述する。2. Description of the Related Art When a laser beam is focused by a lens system, a light spot whose diameter is on the order of the wavelength of the light can be formed. Therefore, it is possible to form a light spot having a high energy density per unit area even from a light source having a small output. An optical information recording medium uses this for recording / reproducing information. Hereinafter, the term "optical recording medium" or simply "medium" will be used.
光記録媒体の基本的な構造は表面が平坦な基板上にレー
ザースポット光照射によって何らかの状態が変化する記
録薄膜層を設けたものである。信号の記録・再生は以下
のような方法を用いる。すなわち、平板状の媒体を例え
ばモーター等による回転手段や並進手段により移動さ
せ、この媒体の記録薄膜面上にレーザー光を収束し照射
する。記録薄膜はレーザー光を吸収し昇温する。レーザ
ー光の出力をある閾値以上に大きくすると記録薄膜の状
態が変化して情報が記録される。この閾値は記録薄膜自
体の特性の他に基材の熱的な特性・媒体の光スポットに
対する相対速度等に依存する量である。記録された情報
は記録部に前記閾値よりも十分低い出力のレーザー光ス
ポットを照射し、その透過光強度、反射光強度あるいは
それらの偏向方向等何らかの光学的特性が記録部と未記
録部で異なることを検出して再生する。The basic structure of an optical recording medium is that a recording thin film layer whose state is changed by laser spot light irradiation is provided on a substrate having a flat surface. The following methods are used for recording / reproducing signals. That is, a flat plate-shaped medium is moved by, for example, a rotating unit such as a motor or a translation unit, and a laser beam is converged and irradiated onto the recording thin film surface of this medium. The recording thin film absorbs laser light and heats up. When the output of laser light is increased above a certain threshold value, the state of the recording thin film changes and information is recorded. This threshold value is an amount that depends on the thermal characteristics of the substrate, the relative speed to the light spot of the medium, and the like in addition to the characteristics of the recording thin film itself. The recorded information is irradiated with a laser beam spot whose output is sufficiently lower than the threshold value, and some optical characteristics such as transmitted light intensity, reflected light intensity or their deflection direction are different between the recorded part and the unrecorded part. It detects that and reproduces.
したがって、小さいレーザーパワーで状態が変化し、大
きな光学的変化を示す材料および構造が望まれる。Therefore, materials and structures that change state with low laser power and exhibit large optical changes are desired.
記録薄膜としてはBi、Teあるいはこれらを主成分とする
金属薄膜、Teを含む化合物薄膜が知られている。これら
はレーザー光照射により薄膜が溶融あるいは蒸発し小孔
を形成する穴開け型の記録を行い、この記録部とその周
辺部からの反射光あるいは透過光の位相が異なるために
干渉で打ち消しあって反射光量あるいは透過光量が変化
することを検出して再生を行う。また、他に相変化型と
呼ばれる。形状の変化を伴わずに光学的な変化をする記
録媒体がある。材料としてはアモルファスカルコゲン化
物薄膜、テルルおよび酸化テルルからなるTe−TeO2を主
成分とする酸化物系薄膜がある（例えば特公昭54−3725
号公報）。また、Te−TeO2−Pdを主成分とする薄膜も知
られている（例えば特開昭61−68296号公報）。これら
はレーザー光照射により薄膜の消衰係数あるいは屈折率
のうち少なくともいずれか１つが変化して記録を行い、
この部分で透過光振幅あるいは反射光振幅が変化するこ
とを検出して信号を再生する。光は波動であり振幅と位
相によって記述される。上記のように信号の再生は透過
光量あるいは反射光量の変化によって検出されるが、そ
の変化の原因としては膜自体の微少領域における透過光
振幅あるいは反射光振幅が変化する場合（振幅変化記
録）と、透過光あるいは反射光の位相が変化する場合
（位相変化記録）がある。なお以下で反射率というのは
光エネルギー（すなわち反射光振幅の２乗）の入射光に
対する出射光の比を言う。As the recording thin film, Bi, Te, a metal thin film containing them as a main component, or a compound thin film containing Te is known. These perform perforation-type recording in which a thin film is melted or evaporated by laser light irradiation to form small holes, and the phases of reflected light or transmitted light from this recording part and its peripheral part are different, so they cancel each other out due to interference. Reproduction is performed by detecting a change in the amount of reflected light or the amount of transmitted light. It is also called a phase change type. There is a recording medium that changes optically without changing its shape. Examples of the material include an amorphous chalcogenide thin film, and an oxide thin film containing tellurium and tellurium oxide as a main component of Te-TeO2 (for example, Japanese Patent Publication No. 54-3725).
Issue). A thin film containing Te-TeO2-Pd as a main component is also known (for example, Japanese Patent Laid-Open No. 61-68296). At least one of the extinction coefficient and the refractive index of the thin film changes due to laser irradiation, and recording is performed.
A signal is reproduced by detecting a change in transmitted light amplitude or reflected light amplitude in this portion. Light is a wave and is described by its amplitude and phase. As described above, the reproduction of the signal is detected by the change in the transmitted light amount or the reflected light amount. The cause of the change is that the transmitted light amplitude or the reflected light amplitude changes in the minute area of the film itself (amplitude change recording). , The phase of transmitted light or reflected light may change (phase change recording). In the following, the term “reflectance” refers to the ratio of light energy (that is, the square of the amplitude of reflected light) to incident light.
発明が解決しようとする課題 以上のような光記録媒体の中で穴開け型のものは反射率
変化は大きく取れ、位相変化記録であるため記録密度が
大きい記録が行えるが、きれいな穴を形成することが難
しく再生時のノイズが大きい。また、密着した保護構造
がとれず、いわゆるエアーサンドイッチ構造といわれる
複雑な中空構造をとる必要があり、製造が難しくコスト
高である。また、変形記録であるので消去書き換えが不
可能である。DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention Among the optical recording media as described above, the perforated type has a large change in reflectance, and since it is phase change recording, recording with a high recording density can be performed, but a clear hole is formed. It is difficult and the noise during playback is large. Further, it is necessary to take a complicated hollow structure, which is a so-called air sandwich structure, because a protective structure in close contact cannot be obtained, which makes manufacturing difficult and costly. In addition, since it is a modified recording, it cannot be erased and rewritten.
これに比べて相変化型の記録媒体は形状変化を伴わない
ので簡単な構造がとれ製造が容易で低コストの媒体であ
るが、穴開け型の記録にくらべて記録密度が小さいとい
う課題がある。さらに、位相変化型の記録媒体である凹
凸ピットによる複製盤（オーディオディスク、ビデオデ
ィスク等）との互換が取りにくいという課題もある。Compared with this, the phase-change recording medium is a medium with a simple structure and easy to manufacture because it does not change the shape, and it is a low-cost medium, but there is a problem that the recording density is smaller than that of the perforation-type recording. . Further, there is a problem in that it is difficult to achieve compatibility with a duplication board (audio disk, video disk, etc.) that has a concave-convex pit that is a phase-change recording medium.
課題を解決するための手段 基材上に、エネルギー線照射によって光学定数が変化す
る薄膜材料を設けて、変化の前後で入射した光の反射光
あるいは透過光の位相が変化しこの位相変化による全体
の反射光量あるいは透過光量の変化を検知する構成とす
る。さらに、その際に変化の前後で透過光振幅あるいは
反射光振幅は変化がない。あるいは小さい構成とする。Means for solving the problem By providing a thin film material whose optical constant is changed by energy beam irradiation on the base material, the phase of the reflected light or the transmitted light of the incident light changes before and after the change, and The configuration is such that a change in the amount of reflected light or the amount of transmitted light is detected. Further, at that time, the transmitted light amplitude or the reflected light amplitude does not change before and after the change. Alternatively, the configuration may be small.
作用 上記のような構成にすると光学的には凹凸による位相変
化記録と等価な記録が行える。従って、相変化記録であ
りながら記録密度の大きい記録が行なえ、凹凸ピットに
よる複製盤（オーディオディスク、ビデオディスク等）
との互換も取り易い。また、相変化記録は形状変化を伴
わず材料を選ぶことによって記録した状態をもとに戻
す、すなわち消去・書き換えも可能であり、書き換え型
の位相変化記録が実現できる。Operation With the above-mentioned configuration, optically equivalent recording to phase change recording by unevenness can be performed. Therefore, although it is a phase change recording, recording with a high recording density can be performed, and a duplication board (audio disc, video disc, etc.) with uneven pits
It is easy to take compatibility with. Further, in the phase change recording, the recorded state can be returned to the original state by selecting a material without changing the shape, that is, erasing / rewriting is possible, and rewritable phase change recording can be realized.
実施例 従来の相変化形光記録媒体の構造の一例を第３図に示
す。相変化記録材料はエネルギー線を照射して発熱昇温
させその相を変化させると複素屈折率が変化する。その
変化は一般的に屈折率と消衰係数が同方向に変化する。
アモルファス状態が結晶状態に変化すると一般に屈折率
と消衰係数が増大する。この様な記録薄膜の反射率は膜
厚t1に依存する。基材側から光を入射した場合の記録薄
膜の反射率Ｒは記録薄膜の光入射側の界面からの反射光
とその反対側の界面からの反射光の多量干渉の結果であ
る。膜厚t1を変化させると反射率は干渉の結果、波長と
屈折率によって決まる周期で増減するが膜厚が増加する
にしたがい吸収により光入射側と反対の界面に到達して
反射する光量が減少するため干渉の効果がなくなってい
く。その結果として干渉による増減が膜厚の増加にとも
ないしだいに減衰する曲線を描く。複素屈折率が大きく
なると屈折率の増加により干渉による膜厚周期が小さく
なると同時に消衰係数の増加により減衰する膜厚が小さ
い方向にシフトする。以上の結果、相変化した時の反射
率差ΔＲも膜厚により変化するが一般には複素屈折率の
小さい相で反射率が極小になる膜厚で極大になる。一方
このような構成では反射光の位相の相変化の前後での変
化は小さい。従来相変化形の記録媒体はこの反射率が極
大になる膜厚で用いていた。従って記録状態の再生はこ
の反射率の差を検出することによってなされる。ミクロ
ンオーダーの微少な領域の記録再生の場合には、記録さ
れた部分の大きさと再生に用いる光ビームの大きさが同
じオーダーになる。例えば、波長800nm前後のレーザー
光をNA0.5程度のレンズ系で絞ると半値幅が約0.9μｍの
ビームに絞れる。この様なビームを用いて強いパワーで
記録を行うと約0.5〜１μｍ前後の範囲が相変化をおこ
して記録状態となる。これを同じビームで読みだす場合
を考えると、読み出しビームの光強度は一般的にはガウ
ス分布あるいはそれに近い形状の分布をしており相変化
した記録状態よりも外側に広がっているため反射光量は
記録状態の反射率と回りの未記録状態の反射率にそれぞ
れの面積と光強度分布を加重して平均した値に比例す
る。したがって、読み出しビームの大きさに比べて十分
大きな範囲の記録状態の面積がないと十分な再生信号が
得られない。この大きさによって記録密度が制限され
る。Example FIG. 3 shows an example of the structure of a conventional phase change type optical recording medium. The complex refractive index of the phase-change recording material changes when the phase is changed by irradiating energy rays to generate heat and raising the temperature. The change generally changes the refractive index and the extinction coefficient in the same direction.
When the amorphous state changes to the crystalline state, the refractive index and the extinction coefficient generally increase. The reflectance of such a recording thin film depends on the film thickness t1. The reflectance R of the recording thin film when light is incident from the base material side is a result of a large amount of interference between the reflected light from the light incident side interface of the recording thin film and the reflected light from the opposite interface. When the film thickness t1 is changed, the reflectance increases or decreases as a result of interference, with a period determined by the wavelength and the refractive index, but as the film thickness increases, the amount of light that reaches the interface opposite the light incident side and reflects decreases due to absorption. As a result, the effect of interference disappears. As a result, a curve is drawn in which the increase / decrease due to interference gradually attenuates as the film thickness increases. When the complex refractive index increases, the film thickness period due to interference decreases due to the increase in the refractive index, and at the same time, the attenuation film thickness shifts toward the smaller direction due to the increase in the extinction coefficient. As a result of the above, the reflectance difference ΔR at the time of phase change also changes depending on the film thickness, but generally it becomes maximum at the film thickness at which the reflectance is minimal in the phase with a small complex refractive index. On the other hand, in such a configuration, the change in the phase of the reflected light before and after the phase change is small. Conventionally, a phase-change type recording medium has been used with a film thickness that maximizes this reflectance. Therefore, reproduction of the recorded state is performed by detecting this difference in reflectance. In the case of recording / reproducing in a minute area of micron order, the size of the recorded portion is the same as the size of the light beam used for reproducing. For example, if a laser beam with a wavelength of around 800 nm is narrowed down by a lens system with an NA of about 0.5, it will be narrowed down to a beam with a half width of about 0.9 μm. When recording is performed with a strong power using such a beam, a phase change occurs in a range of about 0.5 to 1 μm, and a recording state is obtained. Considering the case of reading this with the same beam, the light intensity of the read beam generally has a Gaussian distribution or a distribution of a shape close to it, and the reflected light amount is larger than the phase-changed recording state. It is proportional to the average of the reflectance in the recorded state and the reflectance in the surrounding unrecorded state, weighted by their respective areas and light intensity distributions. Therefore, a sufficient reproduction signal cannot be obtained unless there is a recording state area that is sufficiently larger than the read beam size. This size limits the recording density.
一方、穴開け形の場合には記録状態は凹凸の形状であり
周辺部と記録部からの反射光が干渉しあって反射光量が
変化することを利用している。従って周辺部と穴部での
反射光の位相差が（１±2n）πあるいは±λ/2n:整数、
π：円周率、λ：波長のとき最も反射光量変化が大き
い。また、読み出しビームの強度分布として穴部に入射
する強度と周辺部に入射する強度が等しいとき最も干渉
の効果が大きく、従って、反射光強度変化が大きい。す
なわち、読み出しビームの大きさよりも小さい記録状態
のときが再生信号が大きくとれる。On the other hand, in the case of the perforated type, the recording state has an uneven shape, and the fact that the reflected light from the peripheral portion interferes with the reflected light and the amount of reflected light changes. Therefore, the phase difference between the reflected light at the periphery and the hole is (1 ± 2n) π or ± λ / 2n: integer,
When π is the circular constant and λ is the wavelength, the change in the reflected light amount is the largest. When the intensity distribution of the read beam is equal to the intensity incident on the hole and the intensity incident on the peripheral portion, the effect of interference is greatest, and therefore the change in reflected light intensity is large. That is, the reproduction signal can be large in a recording state smaller than the size of the read beam.
以上から反射率変化記録よりも位相変化記録の方が高密
度な記録再生が出来ることがわかる。From the above, it is understood that the phase change recording can achieve higher density recording / reproducing than the reflectance change recording.
従って、相変化記録において位相変化を得ることが出来
れば凹凸記録並の記録密度が得られる。しかも反射率変
化は無いことあるいは小さいことが望ましい。相変化型
の記録膜材料を用いて上述のような位相変化型の光記録
媒体を構成するには、記録薄膜層の少なくとも片面に基
材あるいは保護層と使用するレーザー光の波長において
屈折率の異なる透明層を設けることによって実現でき
る。記録薄膜に接する材料の屈折率が変化すると各界面
での反射光が変化する。記録薄膜からの反射光は記録薄
膜の光入射側の界面からの反射光とその反対側の界面か
らの反射光の多重干渉の結果である。記録薄膜が十分薄
く記録薄膜の光入射側と反対の界面まで到達する光の大
きさが十分大きい場合には、未記録状態の光学定数の小
さいときは光入射側と反対の界面まで到達して反射され
る光が光入射側の界面からの反射光よりも大きく、記録
状態の光学定数の大きいときは逆に光入射側の界面から
の反射光が光入射側と反対の界面まで到達して反射され
る光よりも大きくなる条件が存在する。両者は光路長が
異なるため位相差を持っている。この位相差が大きけれ
ば干渉による打ち消しあいの結果、記録により光学定数
が変化した時に全体の反射光の位相が大きく変化するこ
とが可能になる。さらに両者の振幅の差が記録の前後で
ほぼ等しければ（もちろん大小関係は逆転するものであ
るが）反射光振幅の変化はほとんどないということが可
能である。Therefore, if the phase change can be obtained in the phase change recording, the recording density comparable to that of the uneven recording can be obtained. Moreover, it is desirable that the reflectance does not change or is small. In order to configure the above-mentioned phase change type optical recording medium using the phase change type recording film material, the base material or the protective layer is provided on at least one surface of the recording thin film layer and the refractive index at the wavelength of the laser light used. This can be achieved by providing different transparent layers. When the refractive index of the material in contact with the recording thin film changes, the reflected light at each interface changes. The reflected light from the recording thin film is the result of multiple interference between the reflected light from the light incident side interface of the recording thin film and the reflected light from the opposite side interface. The recording thin film is thin enough to reach the interface on the opposite side of the light incident side of the recording thin film.If the light intensity is sufficiently large, it reaches the interface on the opposite side of the light incident side when the optical constant in the unrecorded state is small. When the reflected light is larger than the reflected light from the light incident side interface and the optical constant in the recorded state is large, the reflected light from the light incident side interface reaches the interface opposite to the light incident side. There are conditions that make it larger than the reflected light. Both have a phase difference because the optical path lengths are different. If this phase difference is large, as a result of cancellation due to interference, the phase of the entire reflected light can change significantly when the optical constant changes due to recording. Furthermore, if the amplitude difference between the two is almost equal before and after recording (although the magnitude relationship is reversed, of course), it is possible that there is almost no change in the reflected light amplitude.
つぎに、具体的な実施例を使って説明をする。Next, a specific example will be described.
記録媒体の構成としては第１図に示すように基材１上に
透明な誘電体等の光学層３を設けその上に記録薄膜２を
設けさらにその上に透明な密着した保護層４を設ける。
この他に図には示さないが保護層を施さない構成でもよ
い。この場合は保護層の代わりに空気（屈折率1.0）を
考えると光学的には同等であり同じ効果が得られる。ま
た、第２図のように記録薄膜と保護層（あるいは空気
層）とのあいだにさらに透明な誘電体等の光学層3bを設
けた構成でもよい。透明層3,3a,3bには基材１、保護層
（あるいは空気層）４と屈折率の異なる材質を用いる。As the structure of the recording medium, as shown in FIG. 1, an optical layer 3 such as a transparent dielectric is provided on a substrate 1 and a recording thin film 2 is provided thereon, and a transparent protective layer 4 is provided thereon. .
In addition, although not shown in the figure, a structure in which a protective layer is not provided may be used. In this case, considering air (refractive index 1.0) instead of the protective layer, they are optically equivalent and the same effect can be obtained. Further, as shown in FIG. 2, a structure in which a further transparent optical layer 3b such as a dielectric is provided between the recording thin film and the protective layer (or the air layer) may be used. The transparent layers 3, 3a and 3b are made of a material having a refractive index different from that of the substrate 1 and the protective layer (or air layer) 4.
これらの記録薄膜の厚さt1、透明光学層の厚さt2、t3を
適当を選ぶことによって位相変化の大きい媒体を得るこ
とができる。A medium having a large phase change can be obtained by appropriately selecting the thickness t1 of these recording thin films and the thicknesses t2 and t3 of the transparent optical layers.
基材としてはガラス・樹脂等の透明で平滑な平版を用い
る。As the base material, a transparent and flat lithographic plate such as glass or resin is used.
保護層としては樹脂を溶剤に溶かして塗布・乾燥したも
のや樹脂板を接着したもの等が使える。As the protective layer, a resin dissolved in a solvent, applied and dried, or a resin plate adhered can be used.
記録薄膜材料としてはアモルファス・結晶間の相変化を
する材料たとえばSbTe系、InTe系、GeTeSn系、SbSe系、
TeSeSb系、SnTeSe系、InSe系、TeGeSnO系、TeGeSnAu
系、TeGeSnSb系、等のカルコゲン化合物を用いる。Te−
TeO2系、Te−TeO2−Au系、Te−TeO2−Pd系等の酸化物系
材料も使える。また、結晶−結晶間の相転移をするAgZn
系、InSb系等の金属化合物も使える。As the recording thin film material, a material that undergoes a phase change between amorphous and crystal, such as SbTe system, InTe system, GeTeSn system, SbSe system,
TeSeSb system, SnTeSe system, InSe system, TeGeSnO system, TeGeSnAu
System, TeGeSnSb system, and other chalcogen compounds are used. Te−
TeO2-based, Te-TeO2-Au-based, Te-TeO2-Pd-based oxide-based materials can also be used. In addition, AgZn that undergoes a crystal-crystal phase transition
Metal compounds such as Insb series and InSb series can also be used.
透明な光学層としてはSiO2、SiO、TiO2、MgO、GeO2等の
酸化物、Si3N4、BN、等の窒化物、ZnS、ZnTe、PbS等の
硫化物が使える。As the transparent optical layer, oxides such as SiO2, SiO, TiO2, MgO and GeO2, nitrides such as Si3N4 and BN, and sulfides such as ZnS, ZnTe and PbS can be used.
これらの材料を作る方法としては多元蒸着源を用いた真
空蒸着法やモザイク状の複合ターゲットを用いたスパッ
タリング法その他が使える。As a method for producing these materials, a vacuum vapor deposition method using a multi-source vapor deposition source, a sputtering method using a mosaic-shaped composite target, and the like can be used.
比較例 記録薄膜として相変化材料であるTe49028Pd23の組成を
持つ３元化合物を用いる。蒸着法としてTe、TeO2、Pdの
３つの蒸発源を用いた電子ビーム蒸着法を用いる。ガラ
ス板上に上記組成のTe49028Pd23だけを蒸着したアモル
ファス状態の光学定数を測定したところ、波長830nmに
おいて複素屈折率ｎ＋kiが3.1＋1.2iであった。これを3
00℃で５分間熱処理して結晶状態にすると3.9＋1.6iに
変化する。Comparative Example A ternary compound having a composition of Te49028Pd23 which is a phase change material is used as a recording thin film. An electron beam evaporation method using three evaporation sources of Te, TeO2, and Pd is used as the evaporation method. When the optical constant of an amorphous state in which only Te49028Pd23 having the above composition was vapor-deposited on a glass plate was measured, the complex refractive index n + ki was 3.1 + 1.2i at a wavelength of 830 nm. This 3
It changes to 3.9 + 1.6i when it is crystallized by heat treatment at 00 ℃ for 5 minutes.
この膜をポリカーボネート樹脂板（PC、屈折率1.58）上
に蒸着しさらに同じ屈折率の材質の樹脂をコーティング
した第３図のような従来例の構成の場合の熱処理前後す
なわちアモルファス状態と結晶状態での反射率Ｒの変化
のおよび反射光の位相変化の膜厚依存性の計算値を第４
図（ａ）（ｂ）に示す。This film was vapor-deposited on a polycarbonate resin plate (PC, refractive index 1.58) and coated with resin of the same refractive index material before and after heat treatment in the case of the conventional structure as shown in FIG. 3, that is, in an amorphous state and a crystalline state. The calculated value of the film thickness dependence of the change in the reflectance R of the
It shows in figure (a) (b).
反射率の計算には各層の複素屈折率と膜厚からマトリッ
クス法で計算した。（例えば、久保田広著「波動光学」
岩波書店、1971年第３章参照）また、基材１と密着保護
層は３は無限大の膜厚をもつものとして（基材−空気界
面、密着保護層−空気界面の効果を無視）、反射率Ｒは
基材から入射した光の基材中に出射してくる比率として
もとめた。The reflectance was calculated by the matrix method from the complex refractive index and the film thickness of each layer. (For example, "Wave Optics" by Hiro Kubota
(See Iwanami Shoten, Chapter 3, 1971) Also, assuming that the base material 1 and the adhesion protection layer 3 have an infinite film thickness (ignoring the effects of the base material-air interface and the adhesion protection layer-air interface), The reflectance R was calculated as the ratio of the light incident from the base material to be emitted into the base material.
アモルファス状態と結晶状態の反射率差ΔＲは膜厚35nm
および135nmで極大になり10％以上になるが位相変化は
殆どなくπ/4（λ/8）以下である。The reflectance difference ΔR between the amorphous state and the crystalline state is 35 nm.
It becomes maximum at 10 nm and 135 nm and becomes 10% or more, but there is almost no phase change and it is π / 4 (λ / 8) or less.
実施例１ 本発明の一実施例として第１図に示すようにポリカーボ
ネート樹脂板（PC、屈折率1.58）上に透明な光学層とし
てZnS（屈折率2.40）をエレクトロンビーム蒸着法で厚
さ97nm蒸着したうえに比較例にしめした方法で形成しさ
らに同じ基材と屈折率の材質の樹脂をコーティングした
第１図のような構成の場合の熱処理後すなわちアモルフ
ァス状態と結晶状態での反射率Ｒの変化のおよび反射光
の位相変化の膜厚依存性の計算値を第５図（ａ）（ｂ）
に示す。Example 1 As an example of the present invention, as shown in FIG. 1, ZnS (refractive index 2.40) was deposited as a transparent optical layer on a polycarbonate resin plate (PC, refractive index 1.58) by electron beam evaporation to a thickness of 97 nm. In addition, after the heat treatment in the case of the structure as shown in FIG. 1 in which the resin having the same base material and the same material as the refractive index is coated by the method shown in the comparative example, that is, the reflectance R in the amorphous state and the crystalline state is The calculated values of the film thickness dependence of the change and the phase change of the reflected light are shown in FIGS.
Shown in.
記録薄膜の膜厚が20nmのとき反射率変化が殆どなく反射
光の位相変化が約−π（−λ/2）得られることが示され
ている。It is shown that when the thickness of the recording thin film is 20 nm, there is almost no change in reflectance and a phase change of reflected light of about −π (−λ / 2) is obtained.
この計算結果をもとに以下の実験を行った。The following experiments were conducted based on the calculation results.
基材に厚さ1.2mm・直径200mmのPC樹脂円板を用いこれを
真空中で回転させなが上記の方法でZnS薄膜を97nm蒸着
しさらに記録薄膜Te49028Pd23を同様に20nmの膜厚で蒸
着した。さらに同じPC樹脂円盤を紫外線硬化性の接着材
で張り付けて密着保護層を設けた。この円盤を回転させ
線速度5m/secの線速度で波長830nmの半導体レーザー光
を開口数0.5のレンズ系で絞って記録薄膜上に焦点をあ
わせて照射した。記録薄膜面上で8mWの出力で単一周波
数変調度50％で変調した光を反射して記録を行い、1mW
の連続出力を照射してその反射光をフォトディテクター
で検出して再生を行ったところ、第３図に示すような従
来例記録薄膜の膜厚135nmの構成に比べて周波数特性が
高域側に伸びることが確認された。A PC resin disk with a thickness of 1.2 mm and a diameter of 200 mm is used as a base material, and this is not rotated in a vacuum, but a ZnS thin film is deposited to 97 nm by the above method and a recording thin film Te49028Pd23 is similarly deposited to a thickness of 20 nm. . Furthermore, the same PC resin disk was attached with an ultraviolet curable adhesive to form an adhesion protection layer. This disk was rotated, and a semiconductor laser beam having a wavelength of 830 nm was focused at a linear velocity of 5 m / sec with a lens system having a numerical aperture of 0.5 and focused on the recording thin film to be irradiated. Recording was performed by reflecting light that was modulated with a single frequency modulation factor of 50% at an output of 8 mW on the recording thin film surface and recorded.
When continuous reproduction was performed and the reflected light was detected by the photodetector to reproduce, the frequency characteristics were higher than the conventional recording thin film with a thickness of 135 nm as shown in FIG. It was confirmed to grow.
実施例２ 第２図に示すようにポリカーボネート樹脂板（PC、屈折
率1.58）上に透明な光学層としてZnS（屈折率2.40）を
エレクトロビーム蒸着法で厚さ76nm蒸着した上に実施例
１にしめした記録薄膜Te49028Pd23を実施例１にしめし
た方法で形成しさらにZnS層を130nm同様に蒸着し最後に
基材と同じ屈折率の材質の樹脂をコーティングした構成
の場合の熱処理前後すなわちアモルファス状態と結晶状
態での反射率Ｒの変化のおよび反射光の位相変化の膜厚
依存性の計算値を第６図（ａ）（ｂ）に示す。Example 2 As shown in FIG. 2, ZnS (refractive index 2.40) was deposited as a transparent optical layer on a polycarbonate resin plate (PC, refractive index 1.58) to a thickness of 76 nm by an electro-beam evaporation method, and then, in Example 1. A recording thin film Te49028Pd23 is formed by the method described in Example 1, a ZnS layer is vapor-deposited in the same manner as 130 nm, and finally, a resin having the same refractive index as the substrate is coated before and after the heat treatment, that is, in an amorphous state. Calculated values of the film thickness dependence of the change in the reflectance R in the crystalline state and the change in the phase of the reflected light are shown in FIGS. 6 (a) and 6 (b).
記録薄膜の膜厚が30nmのとき反射率変化が殆どなく反射
光の位相変化が約−π（−λ/2）得られることが示され
ている。It is shown that when the film thickness of the recording thin film is 30 nm, there is almost no change in reflectance and a phase change of reflected light of about −π (−λ / 2) is obtained.
実施例３ 第２図に示すようにポリカーボネート樹脂板（PC、屈折
率1.58）上に透明な光学層としてZnS（屈折率2.40）を
エレクトロンビーム蒸着法で厚さ120nm蒸着したうえに
比較例にしめした記録薄膜Te49028Pd23を比較例にしめ
した方法で形成しさらにZnS層を54nm同様に蒸着し最後
に基材と同じ屈折率の材質の樹脂をコーティングした構
成の場合の熱処理前後すなわちアモルファス状態と結晶
状態での反射率Ｒ変化のおよび反射光の位相変化の膜厚
依存性の計算値を第７図（ａ）（ｂ）に示す。Example 3 As shown in FIG. 2, ZnS (refractive index 2.40) was deposited as a transparent optical layer on a polycarbonate resin plate (PC, refractive index 1.58) by an electron beam deposition method to a thickness of 120 nm, and then used as a comparative example. Recording thin film Te49028Pd23 was formed by the method shown in the comparative example, further ZnS layer was vapor-deposited in the same manner as 54 nm, and finally before and after heat treatment in the case of coating with a resin of the same refractive index as the base material, that is, amorphous state and crystalline state Calculated values of the film thickness dependence of the change in reflectance R and the change in the phase of reflected light in Fig. 7 are shown in Figs.
記録薄膜の膜厚が120nmのとき反射率変化が殆どなく反
射光の位相変化が約π/2得られることが示されている。It is shown that there is almost no change in reflectance when the film thickness of the recording thin film is 120 nm, and a phase change of reflected light of about π / 2 is obtained.
発明の効果 本発明によれば光学的には凹凸による位相変化記録と等
価な記録が行える。従って、相変化記録でありながら記
録密度の大きい記録が行え、凹凸ピットによる複製盤
（オーディオディスク、ビデオディスク等）との互換も
取り易い。また、相変化記録は形状変化を伴わず材料を
選ぶことによって記録した状態をもとに戻す、すなわち
消去・書き換えも可能であり、置き換え型の位相変化記
録が実現できる。EFFECTS OF THE INVENTION According to the present invention, recording that is optically equivalent to phase change recording due to unevenness can be performed. Therefore, it is possible to perform recording with a high recording density even though it is phase change recording, and it is easy to obtain compatibility with a duplication disk (audio disk, video disk, etc.) due to uneven pits. Further, in the phase change recording, the recorded state can be returned to the original state by selecting a material without changing the shape, that is, erasing / rewriting can be performed, and replacement type phase change recording can be realized.
第１図は本発明の一実施例の構成を示す模式図、第２図
は本発明の他の実施例の構成を示す模式図、第３図は従
来例の構成を示す模式図、第４図は従来例の構成での反
射率変化と反射光の位相変化の記録薄膜の膜厚依存性を
示すグラフ、第５図は本発明の一実施例の反射率変化と
反射光の位相変化の記録薄膜の膜厚存性を示すグラフ、
第６図・第７図は本発明の他の実施例の反射率変化と反
射光の位相変化の記録薄膜の膜厚依存性を示すグラフで
ある。 １……基材、２……記録薄膜、3,3a,3b……透明層、４
……保護層。FIG. 1 is a schematic diagram showing the constitution of one embodiment of the present invention, FIG. 2 is a schematic diagram showing the constitution of another embodiment of the present invention, FIG. 3 is a schematic diagram showing the constitution of a conventional example, and FIG. FIG. 5 is a graph showing the film thickness dependence of the reflectance change and the phase change of the reflected light in the structure of the conventional example, and FIG. 5 shows the reflectance change and the phase change of the reflected light in one embodiment of the present invention. Graph showing the film thickness of the recording thin film,
FIG. 6 and FIG. 7 are graphs showing the film thickness dependence of the change in reflectance and the change in phase of reflected light in another embodiment of the present invention. 1 ... Substrate, 2 ... Recording thin film, 3,3a, 3b ... Transparent layer, 4
...... Protective layer.
Claims (3)
的に検知し得る変化を生じる薄膜材料を設けた光学的情
報記録媒体であって、薄膜材料はエネルギー線照射によ
り光学定数が変化し、検知し得る変化が主として入射し
た光の反射光あるいは透過光の位相の変化によるもので
あることを特徴とする光学的情報記録媒体。1. An optical information recording medium comprising a thin film material on a base material, the thin film material causing a change which can be optically detected by the irradiation of the energy beam, wherein the thin film material has an optical constant changed by the irradiation of the energy beam. An optical information recording medium characterized in that the detectable change is mainly due to a change in the phase of reflected light or transmitted light of incident light.
幅あるいは反射光振幅の変化が小さいことを特徴とする
請求項１記載の光学的情報記録媒体。2. The optical information recording medium according to claim 1, wherein the change in transmitted light amplitude or reflected light amplitude with respect to the incident light before and after the change is small.
の異なる透明層を設けたことを特徴とする請求項１また
は２記載の光学的情報記録媒体。3. An optical information recording medium according to claim 1, wherein a transparent layer having a refractive index different from that of the substrate is provided on at least one surface of the thin film material.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63227015A JPH07105063B2 (en) | 1988-09-09 | 1988-09-09 | Optical information recording medium |
| DE1989627731 DE68927731T2 (en) | 1988-09-09 | 1989-09-08 | Optical data recording medium and associated recording and playback process |
| EP89309138A EP0360466B1 (en) | 1988-09-09 | 1989-09-08 | Optical information recording medium and information recording and reproducing method therefor |
| US07/865,640 US5249175A (en) | 1988-09-09 | 1992-04-09 | Optical information recording medium and information recording and reproducing method therefor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63227015A JPH07105063B2 (en) | 1988-09-09 | 1988-09-09 | Optical information recording medium |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0273537A JPH0273537A (en) | 1990-03-13 |
| JPH07105063B2 true JPH07105063B2 (en) | 1995-11-13 |
Family
ID=16854181
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63227015A Expired - Lifetime JPH07105063B2 (en) | 1988-09-09 | 1988-09-09 | Optical information recording medium |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07105063B2 (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2897532B2 (en) * | 1992-06-02 | 1999-05-31 | 日本電気株式会社 | Reproduction method of phase change optical disk |
| US5527661A (en) * | 1992-11-25 | 1996-06-18 | Matsushita Electric Industrial Co., Ltd. | Optical information recording medium |
| JP2812181B2 (en) * | 1993-06-17 | 1998-10-22 | 日本電気株式会社 | Optical information recording medium |
| JP3284744B2 (en) * | 1994-04-20 | 2002-05-20 | 松下電器産業株式会社 | Optical information recording medium |
| JP2655093B2 (en) * | 1994-08-29 | 1997-09-17 | 日本電気株式会社 | Optical head and optical disk device |
| JP3138661B2 (en) * | 1996-10-24 | 2001-02-26 | 日本電気株式会社 | Phase change optical disk |
-
1988
- 1988-09-09 JP JP63227015A patent/JPH07105063B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0273537A (en) | 1990-03-13 |
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