JP3506373B2 - Focus control method, information recording medium master creation method, focus control device, and information recording medium master creation device - Google Patents
Focus control method, information recording medium master creation method, focus control device, and information recording medium master creation deviceInfo
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- JP3506373B2 JP3506373B2 JP2000344871A JP2000344871A JP3506373B2 JP 3506373 B2 JP3506373 B2 JP 3506373B2 JP 2000344871 A JP2000344871 A JP 2000344871A JP 2000344871 A JP2000344871 A JP 2000344871A JP 3506373 B2 JP3506373 B2 JP 3506373B2
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- recording medium
- objective lens
- light
- distance
- recording
- Prior art date
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- Optical Recording Or Reproduction (AREA)
- Manufacturing Optical Record Carriers (AREA)
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、光ディスク等の情
報記録媒体の原盤に対する記録光の焦点を制御する焦点
制御方法および焦点制御装置に関するものである。ま
た、本発明は、光ディスク等の情報記録媒体の原盤を作
成する情報記録媒体原盤作成方法および情報記録媒体原
盤作成装置に関するものである。上述の各方法および装
置は、特に、情報を記録する記録光の波長が紫外域であ
り、それを検出できる検出器の感度が低下する場合に好
適である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus control method and a focus control device for controlling the focus of recording light on a master of an information recording medium such as an optical disk. The present invention also relates to an information recording medium master disk manufacturing method and an information recording medium master disk manufacturing apparatus for manufacturing a master disk of an information recording medium such as an optical disk. The above-described methods and apparatuses are particularly suitable when the wavelength of recording light for recording information is in the ultraviolet region and the sensitivity of the detector capable of detecting it decreases.
【０００２】[0002]
【従来の技術】コンパクトディスク（ＣＤ）の普及に伴
い、光ディスクは一般的なものとなってきたが、より高
密度な光ディスクの研究開発が盛んに行われ、近年では
ＣＤよりもさらに高密度なディジタルビデオディスク
（ＤＶＤ）が提案され、実用化されている。そして、今
後更なる高密度の光ディスクの開発が急がれている。そ
のためには、より微細な記録のできる高密度な情報記録
媒体原盤作成技術が非常に重要である。2. Description of the Related Art With the spread of compact discs (CDs), optical discs have become popular, but research and development of higher density optical discs have been actively conducted, and in recent years, optical discs with higher density than CDs have been developed. A digital video disc (DVD) has been proposed and put into practical use. In the future, the development of higher density optical discs is urgently needed. For that purpose, a technique for producing a high density information recording medium master disk capable of finer recording is very important.
【０００３】従来の情報記録媒体原盤作成方法では、波
長６３３ｎｍのＨｅ−Ｎｅレーザー光にほとんど感度を
有さないフォトレジストを塗布したガラス基材（ディス
ク）に、制御光としてＨｅ−Ｎｅレーザー光を対物レン
ズを通して照射し、Ｈｅ−Ｎｅレーザー光を用いて焦点
制御が行われる。具体的に説明すると、Ｈｅ−Ｎｅレー
ザー光を対物レンズを通して照射し、ガラス基材からの
反射光の変化によって対物レンズとガラス基材の距離が
一定になるようにフィードバック制御を行う焦点制御光
学系によって焦点制御が行われる。In the conventional method for producing an information recording medium master disk, a He-Ne laser beam is used as a control light on a glass substrate (disk) coated with a photoresist having little sensitivity to a He-Ne laser beam having a wavelength of 633 nm. Irradiation is performed through an objective lens, and focus control is performed using He-Ne laser light. Specifically, a focus control optical system that irradiates He-Ne laser light through an objective lens and performs feedback control so that the distance between the objective lens and the glass substrate becomes constant due to a change in reflected light from the glass substrate. Focus control is performed by.
【０００４】また、ピットを記録する記録光としてフォ
トレジストが感度を有する波長４５８ｎｍ等のレーザー
光を同じ対物レンズを通して集光して断続的にガラス基
材に照射し、ガラス基材上のフォトレジストを現像する
ことによって、記録光の変調信号に対応したピットが形
成される。Further, as a recording light for recording a pit, a laser beam having a wavelength of 458 nm, which is sensitive to a photoresist, is condensed through the same objective lens and is intermittently irradiated on the glass substrate to form a photoresist on the glass substrate. Is developed to form a pit corresponding to the modulation signal of the recording light.
【０００５】また、一方では、Ｈｅ−Ｎｅレーザー光と
いった記録光とは別の制御光を用いる代わりに、記録光
そのものでフィードバック制御を行う焦点制御方法も提
案され実用化されている。On the other hand, instead of using control light such as He-Ne laser light which is different from recording light, a focus control method in which feedback control is performed by the recording light itself has also been proposed and put into practical use.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、前述の
記録光と別の制御光を用いる従来の焦点制御方法では、
フィードバック制御における対物レンズの制御位置、す
なわち、対物レンズと記録媒体の距離は、焦点制御光学
系により決まり、記録光の状態とは無関係である。However, in the conventional focus control method using the control light different from the recording light described above,
The control position of the objective lens in the feedback control, that is, the distance between the objective lens and the recording medium is determined by the focus control optical system and is independent of the state of the recording light.
【０００７】従来、この方法の場合には、必要なディス
クのデータ記録領域以外で記録の開始以前に、記録光の
状態を確認してフォーカス制御の位置を最適位置に調整
することが行われる。そして、実際の記録中はフォーカ
ス制御位置を固定のままでガラス基材と対物レンズの距
離を一定とするフィードバック制御が行われる。そのた
め、記録中に記録光の状態が変化してフォーカス制御の
位置からずれた場合、焦点制御光学系では検出できず、
それを直すことができなかった。Conventionally, in the case of this method, the focus control position is adjusted to the optimum position by checking the state of the recording light before starting recording in a region other than the required data recording area of the disc. Then, during actual recording, feedback control is performed in which the focus control position is fixed and the distance between the glass substrate and the objective lens is constant. Therefore, if the state of the recording light changes during recording and deviates from the focus control position, it cannot be detected by the focus control optical system.
I couldn't fix it.
【０００８】上記のような記録中の記録光の状態の変化
は、例えば以下のようなことが原因となって発生する。
例えば、情報記録媒体原盤作成装置の構成要素である記
録光用レーザー光の広がり角の変化、ビームエキスパン
ダーのレンズホルダーの温度変化に起因した２つのレン
ズ間の距離変化による記録光そのものの変化によって発
生する。あるいは、移動光学台上に位置する焦点制御光
学系の光学部品ホルダーの温度変化に起因した位置およ
び角度の変化により、光軸の位置が変化し、焦点制御の
目標位置が変化する事により発生する。このような記録
光自体の変化もしくは焦点制御の目標位置の変化によっ
て、記録動作中に焦点制御の目標位置が、記録光の最適
な集光位置から変化する。The change in the state of the recording light during recording as described above occurs due to, for example, the following.
For example, it is caused by a change in the divergence angle of the laser light for recording light, which is a component of the information recording medium master disk making device, and a change in the recording light itself due to a change in the distance between the two lenses caused by a temperature change in the lens holder of the beam expander. To do. Alternatively, it occurs when the position of the optical axis changes due to the change in the position and angle of the optical component holder of the focus control optical system located on the moving optical table due to the temperature change, and the target position for focus control changes. . Due to such a change in the recording light itself or a change in the target position for focus control, the target position for focus control changes from the optimum focus position of the recording light during the recording operation.
【０００９】一方、記録光そのものでフィードバック制
御を行う方法では、上記のフォーカス位置ずれの問題は
解決できる。ところが、現在導入されている紫外線を用
いた情報記録媒体原盤記録装置では、記録光の強度が弱
いために記録媒体からの反射光が弱く、かつ光の検出装
置の感度が低いため、フォーカス制御のフィードバック
制御を行うのに十分な信号が得られにくい。On the other hand, the method of performing feedback control using the recording light itself can solve the above-mentioned problem of focus position shift. However, in the information recording medium master disk recording apparatus using ultraviolet rays which has been introduced at present, the intensity of recording light is weak, the reflected light from the recording medium is weak, and the sensitivity of the light detecting device is low, so that the focus control It is difficult to obtain a sufficient signal for feedback control.
【００１０】また、ガラス基材（ガラス盤）の表面に感
光性材料膜（フォトレジスト）を塗布した記録媒体に記
録光を照射して感光性材料膜を露光した後現像すること
により記録媒体の感光性材料膜に楕円形のピットもしく
は連続した溝を形成する。その際に焦点制御系は、記録
光の焦点が感光性材料膜の表面に合致することを目標と
して焦点制御を行うことになる。A recording medium having a surface of a glass substrate (glass plate) coated with a photosensitive material film (photoresist) is irradiated with recording light to expose the photosensitive material film, and then developed to develop the recording medium. Elliptical pits or continuous grooves are formed in the photosensitive material film. At that time, the focus control system performs the focus control with the aim of making the focus of the recording light coincide with the surface of the photosensitive material film.
【００１１】しかしながら、このように、感光性材料膜
の表面が焦点位置になるように焦点制御が行われると、
感光性材料膜の膜厚が焦点制御系において無視できない
値であるため、記録光が感光性材料膜の表面から入射し
てガラス基材と感光性材料膜との接合面に達するまでに
徐々に拡がっていくことになる。この状態で感光性材料
膜を露光した場合には、感光性材料膜中での記録光の平
均的な直径が大きくなり、微細なピットを精度よく形成
することが困難となる。However, when the focus control is performed so that the surface of the photosensitive material film is at the focus position in this way,
Since the thickness of the photosensitive material film is a value that cannot be ignored in the focus control system, the recording light gradually enters from the surface of the photosensitive material film until it reaches the bonding surface between the glass substrate and the photosensitive material film. It will spread. When the photosensitive material film is exposed in this state, the average diameter of the recording light in the photosensitive material film becomes large, and it becomes difficult to form fine pits with high accuracy.
【００１２】また、焦点制御系には、焦点制御が安定し
てなされている状態においても、フィードバック系のゲ
インで決まる残差（一般的に言われるフォーカス残差）
が存在し、その残差の範囲内で焦点制御位置が変動して
いる。したがって、感光性材料膜の表面が焦点位置にな
るように焦点制御が行われる状態においては、フォーカ
ス残差に応じて記録光の焦点位置も変動し、感光性材料
膜の外に位置する状態が生じる。この場合に焦点ずれが
大きくなり、記録光の平均的な直径がさらに大きくな
り、微細なピットを精度よく形成することがさらに困難
となる。Further, in the focus control system, a residual error (generally called focus residual error) determined by the gain of the feedback system even in a state where the focus control is stably performed.
Exists, and the focus control position fluctuates within the range of the residual. Therefore, in the state where the focus control is performed so that the surface of the photosensitive material film becomes the focal position, the focal position of the recording light also changes according to the focus residual, and the state of being positioned outside the photosensitive material film is Occurs. In this case, defocus becomes large, the average diameter of recording light becomes larger, and it becomes more difficult to form fine pits with high accuracy.
【００１３】したがって、本発明の目的は、微細なピッ
トを精度よく形成することができる焦点制御方法および
焦点制御装置と、情報記録媒体原盤作成方法および情報
記録媒体原盤作成装置とを提供することである。Therefore, an object of the present invention is to provide a focus control method and a focus control apparatus capable of accurately forming fine pits, an information recording medium master disk manufacturing method, and an information recording medium master disk manufacturing apparatus. is there.
【００１４】[0014]
【００１５】[0015]
【００１６】[0016]
【課題を解決するための手段】本発明の焦点制御方法
は、記録する情報に応じて変調される記録光を、基材の
表面に感光材料膜が形成された記録媒体との距離が一定
となるように焦点制御された対物レンズを通して集光
し、記録媒体上に情報を記録する情報記録媒体原盤作成
装置の焦点制御方法であり、対物レンズの焦点位置が感
光材料膜の表面から内部へ向かって厚み方向に感光材料
膜の膜厚より少ない所定の微少距離だけ変位した状態に
対物レンズの焦点制御を実行する。上記した所定の微少
距離は、感光材料膜の膜厚の略１／３から略２／３の範
囲の値である。 According to the focus control method of the present invention, recording light modulated according to information to be recorded is kept at a constant distance from a recording medium having a photosensitive material film formed on the surface of a substrate. This is a focus control method for an information recording medium master disk manufacturing apparatus that collects information on a recording medium by collecting light through an objective lens whose focus is controlled so that the focus position of the objective lens goes from the surface of the photosensitive material film to the inside. Then, the focus control of the objective lens is executed in a state where it is displaced in the thickness direction by a predetermined minute distance smaller than the film thickness of the photosensitive material film. Prescribed minute amount mentioned above
The distance is in the range of approximately 1/3 to 2/3 of the film thickness of the photosensitive material film.
It is the value of the box.
【００１７】この方法によれば、対物レンズの焦点位置
が感光材料膜の表面から内部へ向かって厚み方向に感光
材料膜の膜厚より少ない所定の微少距離だけ変位した状
態に対物レンズの焦点制御を実行するので、感光材料膜
中での記録光の拡がりを少なくでき、したがって感光材
料膜中での記録光の平均的直径を小さくできる。その結
果、微細なピットを精度よく形成することが可能とな
る。According to this method, the focus control of the objective lens is performed such that the focal position of the objective lens is displaced inward in the thickness direction from the surface of the photosensitive material film by a predetermined minute distance smaller than the film thickness of the photosensitive material film. Therefore, the spread of the recording light in the photosensitive material film can be reduced, and therefore the average diameter of the recording light in the photosensitive material film can be reduced. As a result, fine pits can be accurately formed.
【００１８】 上記した所定の微少距離は、感光材料膜
の膜厚の略１／２の値が最も好ましい。The predetermined minute distance described above, the value of approximately half the thickness of the sensitive light material film is most preferred.
【００１９】このように設定すれば、フォーカス残差に
応じて記録光の焦点位置が変動しても、焦点位置が感光
性材料膜の外に位置する状態が生じるのを抑止すること
ができ、微細なピットをさらに精度よく形成することが
できる。With this setting, even if the focal position of the recording light varies according to the focus residual, it is possible to prevent the focal position from being located outside the photosensitive material film. Fine pits can be formed more accurately.
【００２０】また、対物レンズの焦点制御は、例えば、
記録光よりも波長が長い別の光を用いて対物レンズと記
録媒体の距離を一定とするフィードバック制御を行い、
かつ記録光が記録媒体から反射された反射光を使って対
物レンズと記録媒体の距離と所望の距離とのずれを検出
し、検出したずれに基づいて対物レンズと記録媒体の距
離が所望の距離になるようにフィードバック制御の制御
目標位置を補正することにより、実行される。The focus control of the objective lens is performed by, for example,
Performs feedback control to make the distance between the objective lens and the recording medium constant by using another light having a longer wavelength than the recording light,
Also, the deviation of the distance between the objective lens and the recording medium and the desired distance is detected by using the reflected light of the recording light reflected from the recording medium, and the distance between the objective lens and the recording medium is the desired distance based on the detected deviation. It is executed by correcting the control target position of the feedback control so that
【００２１】この方法によれば、対物レンズと記録媒体
の距離を一定に保つフォーカス制御を、良好なＳ／Ｎ特
性を得るために光検出装置の感度が十分にとれる赤色等
の長波長光を用いて行い、記録光が記録媒体から反射さ
れた反射光を使って対物レンズと記録媒体の距離と所望
の距離とのずれを検出し、検出したずれに基づいて対物
レンズと記録媒体の距離が所望の距離になるようにフィ
ードバック制御の制御目標位置を補正するので、検出器
の感度が低下する紫外域のレーザー光を記録光として用
いる場合でも、良好なフォーカス制御特性を有した上
で、常にフォーカス制御の位置を最適位置に維持でき
る。According to this method, the focus control for keeping the distance between the objective lens and the recording medium constant is performed by using long-wavelength light such as red, which has sufficient sensitivity of the photodetector to obtain a good S / N characteristic. The distance between the objective lens and the recording medium is detected using the reflected light that is the recording light reflected from the recording medium, and the distance between the objective lens and the recording medium is determined based on the detected deviation. Since the control target position of the feedback control is corrected so that the desired distance is obtained, even when using the laser light in the ultraviolet region where the sensitivity of the detector decreases as the recording light, it always has good focus control characteristics and always has The position of focus control can be maintained at the optimum position.
【００２２】[0022]
【００２３】[0023]
【００２４】[0024]
【００２５】[0025]
【００２６】[0026]
【００２７】 本発明の情報記録媒体原盤作成方法は、
記録する情報に応じて変調される記録光を、記録媒体と
の距離が一定となるように焦点制御された対物レンズを
通して集光し、記録媒体上に情報を記録する情報記録媒
体原盤作成方法であり、対物レンズの焦点位置が感光材
料膜の表面から内部へ向かって厚み方向に感光材料膜の
膜厚より少ない所定の微少距離だけ変位した状態に対物
レンズの焦点制御を実行する。上記した所定の微少距離
は、感光材料膜の膜厚の略１／３から略２／３の範囲の
値である。 The information recording medium master disc forming method of the present invention is
A method for producing an information recording medium master disc in which recording light modulated according to information to be recorded is condensed through an objective lens whose focus is controlled so that the distance to the recording medium is constant and information is recorded on the recording medium. The focus control of the objective lens is executed in a state in which the focal position of the objective lens is displaced inward from the surface of the photosensitive material film in the thickness direction by a predetermined minute distance smaller than the film thickness of the photosensitive material film. Prescribed minute distance mentioned above
Is in the range of about 1/3 to about 2/3 of the film thickness of the photosensitive material film.
It is a value.
【００２８】この方法によれば、対物レンズの焦点位置
が感光材料膜の表面から内部へ向かって厚み方向に感光
材料膜の膜厚より少ない所定の微少距離だけ変位した状
態に対物レンズの焦点制御を実行するので、感光材料膜
中での記録光の拡がりを少なくでき、したがって感光材
料膜中での記録光の平均的直径を小さくできる。その結
果、微細なピットを精度よく形成することが可能とな
る。According to this method, the focus control of the objective lens is performed such that the focal position of the objective lens is displaced inward from the surface of the photosensitive material film in the thickness direction by a predetermined minute distance smaller than the film thickness of the photosensitive material film. Therefore, the spread of the recording light in the photosensitive material film can be reduced, and therefore the average diameter of the recording light in the photosensitive material film can be reduced. As a result, fine pits can be accurately formed.
【００２９】 上記した所定の微少距離は、感光材料膜
の膜厚の略１／２の値が最も好ましい。The predetermined minute distance described above, the value of approximately half the thickness of the sensitive light material film is most preferred.
【００３０】このように設定すれば、フォーカス残差に
応じて記録光の焦点位置が変動しても、焦点位置が感光
性材料膜の外に位置する状態が生じるのを抑止すること
ができ、微細なピットをさらに精度よく形成することが
できる。With this setting, even if the focal position of the recording light varies depending on the focus residual, it is possible to prevent the focal position from being located outside the photosensitive material film. Fine pits can be formed more accurately.
【００３１】また、対物レンズの焦点制御は、例えば記
録光よりも波長が長い別の光を用いて対物レンズと記録
媒体の距離を一定とするフィードバック制御を行い、か
つ記録光が記録媒体から反射された反射光を使って対物
レンズと記録媒体の距離と所望の距離とのずれを検出
し、検出したずれに基づいて対物レンズと記録媒体の距
離が所望の距離になるようにフィードバック制御の制御
目標位置を補正することにより、実行される。In the focus control of the objective lens, feedback control is performed to make the distance between the objective lens and the recording medium constant by using another light having a longer wavelength than the recording light, and the recording light is reflected from the recording medium. The difference between the distance between the objective lens and the recording medium and the desired distance is detected using the reflected light, and the feedback control is controlled so that the distance between the objective lens and the recording medium becomes the desired distance based on the detected deviation. It is executed by correcting the target position.
【００３２】この方法によれば、対物レンズと記録媒体
の距離を一定に保つフォーカス制御を、良好なＳ／Ｎ特
性を得るために光検出装置の感度が十分にとれる赤色等
の長波長光を用いて行い、記録光が記録媒体から反射さ
れた反射光を使って対物レンズと記録媒体の距離と所望
の距離とのずれを検出し、検出したずれに基づいて対物
レンズと記録媒体の距離が所望の距離になるようにフィ
ードバック制御の制御目標位置を補正するので、検出器
の感度が低下する紫外域のレーザー光を記録光として用
いる場合でも、良好なフォーカス制御特性を有した上
で、常にフォーカス制御の位置を最適位置に維持でき
る。According to this method, the focus control for keeping the distance between the objective lens and the recording medium constant is performed by using the long-wavelength light such as red, which allows the photodetector to have sufficient sensitivity to obtain a good S / N characteristic. The distance between the objective lens and the recording medium is detected using the reflected light that is the recording light reflected from the recording medium, and the distance between the objective lens and the recording medium is determined based on the detected deviation. Since the control target position of the feedback control is corrected so that the desired distance is obtained, even when using the laser light in the ultraviolet region where the sensitivity of the detector decreases as the recording light, it always has good focus control characteristics and always has The position of focus control can be maintained at the optimum position.
【００３３】[0033]
【００３４】[0034]
【００３５】 本発明の焦点制御装置は、記録する情報
に応じて変調される記録光を、記録媒体との距離が一定
となるように焦点制御された対物レンズを通して集光
し、記録媒体上に情報を記録する情報記録媒体原盤作成
装置に使用される焦点制御装置であり、対物レンズの焦
点位置が感光材料膜の表面から内部へ向かって厚み方向
に感光材料膜の膜厚より少ない所定の微少距離だけ変位
した状態に対物レンズの焦点制御を実行する焦点制御手
段を設けたことを特徴とする。上記した所定の微少距離
は、感光材料膜の膜厚の略１／３から略２／３の範囲の
値である。 The focus control device of the present invention collects the recording light modulated according to the information to be recorded through the objective lens whose focus is controlled so that the distance to the recording medium is constant, and then the recording light is recorded on the recording medium. A focus control device used in an information recording medium master disk forming device for recording information, in which the focal position of the objective lens is smaller than the film thickness of the photosensitive material film in the thickness direction from the surface of the photosensitive material film toward the inside. It is characterized in that focus control means for executing focus control of the objective lens in a state displaced by a distance is provided. Prescribed minute distance mentioned above
Is in the range of about 1/3 to about 2/3 of the film thickness of the photosensitive material film.
It is a value.
【００３６】この構成によれば、対物レンズの焦点位置
が感光材料膜の表面から内部へ向かって厚み方向に感光
材料膜の膜厚より少ない所定の微少距離だけ変位した状
態に対物レンズの焦点制御を実行するので、感光材料膜
中での記録光の拡がりを少なくでき、したがって感光材
料膜中での記録光の平均的直径を小さくできる。その結
果、微細なピットを精度よく形成することが可能とな
る。According to this structure, the focus control of the objective lens is performed such that the focal position of the objective lens is displaced inward from the surface of the photosensitive material film in the thickness direction by a predetermined minute distance smaller than the film thickness of the photosensitive material film. Therefore, the spread of the recording light in the photosensitive material film can be reduced, and therefore the average diameter of the recording light in the photosensitive material film can be reduced. As a result, fine pits can be accurately formed.
【００３７】 上記した所定の微少距離は、感光材料膜
の膜厚の略１／２の値が最も好ましい。The predetermined minute distance described above, the value of approximately half the thickness of the sensitive light material film is most preferred.
【００３８】このように設定すれば、フォーカス残差に
応じて記録光の焦点位置が変動しても、焦点位置が感光
性材料膜の外に位置する状態が生じるのを抑止すること
ができ、微細なピットをさらに精度よく形成することが
できる。With this setting, even if the focal position of the recording light varies depending on the focus residual, it is possible to prevent the focal position from being located outside the photosensitive material film. Fine pits can be formed more accurately.
【００３９】また、焦点制御手段は、例えば記録光より
も波長が長い別の光を用いて対物レンズと記録媒体の距
離を一定に保つフィードバック制御手段と、記録光が記
録媒体で反射された反射光を用いて対物レンズと記録媒
体の距離と所望の距離とのずれを検出する位置検出手段
と、位置検出手段により検出されたずれに基づいて対物
レンズと記録媒体の距離が所望の距離になるようにフィ
ードバック制御手段の制御目標位置を補正する制御位置
補正手段とからなる。The focus control means is, for example, feedback control means for keeping the distance between the objective lens and the recording medium constant by using another light having a longer wavelength than the recording light, and reflection of the recording light reflected by the recording medium. Position detecting means for detecting a deviation between the desired distance and the distance between the objective lens and the recording medium using light, and the desired distance between the objective lens and the recording medium based on the deviation detected by the position detecting means. Thus, the control position correcting means for correcting the control target position of the feedback control means is provided.
【００４０】この構成によれば、対物レンズと記録媒体
の距離を一定に保つフォーカス制御を、良好なＳ／Ｎ特
性を得るために光検出装置の感度が十分にとれる赤色等
の長波長光を用いて行い、記録光が記録媒体から反射さ
れた反射光を使って対物レンズと記録媒体の距離と所望
の距離とのずれを検出し、検出したずれに基づいて対物
レンズと記録媒体の距離が所望の距離になるようにフィ
ードバック制御の制御目標位置を補正するので、検出器
の感度が低下する紫外域のレーザー光を記録光として用
いる場合でも、良好なフォーカス制御特性を有した上
で、常にフォーカス制御の位置を最適位置に維持でき
る。According to this structure, the focus control for keeping the distance between the objective lens and the recording medium constant is performed by using the long-wavelength light such as red, which has sufficient sensitivity of the photodetector to obtain a good S / N characteristic. The distance between the objective lens and the recording medium is detected using the reflected light that is the recording light reflected from the recording medium, and the distance between the objective lens and the recording medium is determined based on the detected deviation. Since the control target position of the feedback control is corrected so that the desired distance is obtained, even when using the laser light in the ultraviolet region where the sensitivity of the detector decreases as the recording light, it always has good focus control characteristics and always has The position of focus control can be maintained at the optimum position.
【００４１】[0041]
【００４２】[0042]
【００４３】[0043]
【００４４】[0044]
【００４５】[0045]
【００４６】 本発明の情報記録媒体原盤作成装置は、
記録する情報に応じて変調される記録光を、記録媒体と
の距離が一定となるように焦点制御された対物レンズを
通して集光し、記録媒体上に情報を記録する情報記録媒
体原盤作成装置であり、対物レンズの焦点位置が感光材
料膜の表面から内部へ向かって厚み方向に感光材料膜の
膜厚より少ない所定の微少距離だけ変位した状態に対物
レンズの焦点制御を実行する焦点制御手段を設けたこと
を特徴とする。上記した所定の微少距離は、感光材料膜
の膜厚の略１／３から略２／３の範囲の値である。 The information recording medium master disk producing apparatus of the present invention is
An information recording medium master disc forming apparatus for condensing recording light modulated according to information to be recorded through an objective lens whose focus is controlled so that the distance to the recording medium is constant and recording information on the recording medium. There is a focus control means for executing the focus control of the objective lens in a state in which the focus position of the objective lens is displaced inward from the surface of the photosensitive material film in the thickness direction by a predetermined minute distance smaller than the film thickness of the photosensitive material film. It is characterized by being provided. The above-mentioned predetermined minute distance is the photosensitive material film.
Is a value in the range of about 1/3 to about 2/3 of the film thickness.
【００４７】この構成によれば、対物レンズの焦点位置
が感光材料膜の表面から内部へ向かって厚み方向に感光
材料膜の膜厚より少ない所定の微少距離だけ変位した状
態に対物レンズの焦点制御を実行するので、感光材料膜
中での記録光の拡がりを少なくでき、したがって感光材
料膜中での記録光の平均的直径を小さくできる。その結
果、微細なピットを精度よく形成することが可能とな
る。According to this structure, the focus control of the objective lens is performed such that the focal position of the objective lens is displaced inward from the surface of the photosensitive material film in the thickness direction by a predetermined minute distance smaller than the film thickness of the photosensitive material film. Therefore, the spread of the recording light in the photosensitive material film can be reduced, and therefore the average diameter of the recording light in the photosensitive material film can be reduced. As a result, fine pits can be accurately formed.
【００４８】上記した所定の微少距離は、感光材料膜の
膜厚の略１／２の値が最も好ましい。The predetermined minute distance described above, the value of approximately half the thickness of the sensitive light material film is most preferred.
【００４９】このように設定すれば、フォーカス残差に
応じて記録光の焦点位置が変動しても、焦点位置が感光
性材料膜の外に位置する状態が生じるのを抑止すること
ができ、微細なピットをさらに精度よく形成することが
できる。With this setting, even if the focal position of the recording light varies depending on the focus residual, it is possible to prevent the focal position from being located outside the photosensitive material film. Fine pits can be formed more accurately.
【００５０】また、焦点制御手段は、例えば記録光より
も波長が長い別の光を用いて対物レンズと記録媒体の距
離を一定に保つフィードバック制御手段と、記録光が記
録媒体で反射された反射光を用いて対物レンズと記録媒
体の距離と所望の距離とのずれを検出する位置検出手段
と、位置検出手段により検出されたずれに基づいて対物
レンズと記録媒体の距離が所望の距離になるようにフィ
ードバック制御手段の制御目標位置を補正する制御位置
補正手段からなる。The focus control means is, for example, feedback control means for keeping the distance between the objective lens and the recording medium constant by using another light having a longer wavelength than the recording light, and reflection of the recording light reflected by the recording medium. Position detecting means for detecting a deviation between the desired distance and the distance between the objective lens and the recording medium using light, and the desired distance between the objective lens and the recording medium based on the deviation detected by the position detecting means. Thus, the feedback control means is composed of control position correcting means for correcting the control target position.
【００５１】この構成によれば、対物レンズと記録媒体
の距離を一定に保つフォーカス制御を、良好なＳ／Ｎ特
性を得るために光検出装置の感度が十分にとれる赤色等
の長波長光を用いて行い、記録光が記録媒体から反射さ
れた反射光を使って対物レンズと記録媒体の距離と所望
の距離とのずれを検出し、検出したずれに基づいて対物
レンズと記録媒体の距離が所望の距離になるようにフィ
ードバック制御の制御目標位置を補正するので、検出器
の感度が低下する紫外域のレーザー光を記録光として用
いる場合でも、良好なフォーカス制御特性を有した上
で、常にフォーカス制御の位置を最適位置に維持でき
る。According to this structure, the focus control for keeping the distance between the objective lens and the recording medium constant is performed by using long-wavelength light such as red, which is sufficient for the sensitivity of the photodetector to obtain a good S / N characteristic. The distance between the objective lens and the recording medium is detected using the reflected light that is the recording light reflected from the recording medium, and the distance between the objective lens and the recording medium is determined based on the detected deviation. Since the control target position of the feedback control is corrected so that the desired distance is obtained, even when using the laser light in the ultraviolet region where the sensitivity of the detector decreases as the recording light, it always has good focus control characteristics and always has The position of focus control can be maintained at the optimum position.
【００５２】[0052]
【００５３】[0053]
【００５４】[0054]
【発明の実施の形態】以下、本発明の焦点制御方法と焦
点位置ずれ検出方法と情報記録媒体原盤作成方法と焦点
制御装置と焦点位置ずれ検出装置と情報記録媒体原盤作
成装置に関する実施例について、図面を参照しながら説
明する。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments relating to a focus control method, a focus position deviation detection method, an information recording medium master recording method, a focus control device, a focus position deviation detection device, and an information recording medium master recording apparatus according to the present invention will be described below. A description will be given with reference to the drawings.
【００５５】図１は、本発明の実施例における情報記録
媒体原盤作成装置の構成を示す概略図である。この情報
記録媒体原盤作成装置においては、図１に示すように、
記録光源１０１であるアルゴンイオンレーザーを出た波
長３５１ｎｍの記録光は、ミラー１０２によって略直角
に反射され、光強度調整器１０３によって光強度の調整
がなされる。FIG. 1 is a schematic diagram showing the structure of an information recording medium master disk forming apparatus according to an embodiment of the present invention. In this information recording medium master disc forming apparatus, as shown in FIG.
The recording light with a wavelength of 351 nm emitted from the argon ion laser which is the recording light source 101 is reflected by the mirror 102 at a substantially right angle, and the light intensity adjuster 103 adjusts the light intensity.
【００５６】光強度の調整がなされた光は、つぎに光変
調器１０４によって記録すべき情報に応じて変調され、
さらにミラー１０５により略直角に反射され、ビームエ
キスパンダー１０６によって拡大されかつ平行光とな
る。The light whose intensity is adjusted is then modulated by the optical modulator 104 according to the information to be recorded,
Further, the light is reflected by the mirror 105 at a substantially right angle, expanded by the beam expander 106, and becomes parallel light.
【００５７】上記の平行光は、ビームスプリッタ１０７
によって、一部が略直角に反射され、残りは透過して移
動光学台１１３に導かれる。反射された光は、平凸レン
ズ１０８により集光されてフォトダイオード１０９に入
射し、その出力により記録光の平均強度が監視される。The above parallel light is converted into the beam splitter 107.
Thus, a part of the light is reflected at a substantially right angle and the rest is transmitted and guided to the moving optical table 113. The reflected light is condensed by the plano-convex lens 108 and enters the photodiode 109, and the average intensity of the recording light is monitored by the output thereof.
【００５８】移動光学台１１３上には、波長６３３ｎｍ
のＨｅ−Ｎｅレーザーを使い、斜め入射法により焦点制
御を行う焦点制御光学系１１４と、記録光源１０１から
出る記録光と焦点制御光学系１１４から出る焦点制御光
を合成する第１の２色性ミラー１１５と、記録光および
焦点制御光の両波長の光を反射する第２の２色性ミラー
１１６と、記録光を集光するアクチュエータ１１８付き
の対物レンズ１１７とが配されている。A wavelength of 633 nm is displayed on the moving optical table 113.
Second dichroism for synthesizing recording light emitted from the recording light source 101 and focus control light emitted from the focus control optical system 114, and a focus control optical system 114 for performing focus control by the oblique incidence method using the He-Ne laser of A mirror 115, a second dichroic mirror 116 that reflects light of both wavelengths of recording light and focus control light, and an objective lens 117 with an actuator 118 that focuses recording light are arranged.
【００５９】移動光学台１１３に入射した記録光は、対
物レンズ１１７で集光されて記録媒体１１２に照射さ
れ、照射光の一部は記録媒体１１２の表面、すなわちフ
ォトレジストの表面で反射されてビームスプリッタ１０
７へ戻る。反射光の一部はビームスプリッタ１０７によ
り略直角に反射され、レンズ１１０で集光され、ＣＣＤ
カメラ１１１の受光面上に結像する。この際、ＣＣＤカ
メラ１１１の受光面と記録媒体１１２とは共焦点となる
ように配される。上記の記録媒体１１２は、例えば透明
な円形のガラス盤等のガラス基材の表面にフォトレジス
ト等の感光性材料膜を５０〜１００ｎｍ程度の膜厚で塗
布して形成したものである。感光性材料膜は、アルゴン
イオンレーザーを出た波長３５１ｎｍの記録光に感度を
有し、波長６３３ｎｍのＨｅ−Ｎｅレーザー光には感度
を有さない。The recording light incident on the moving optical table 113 is condensed by the objective lens 117 and is irradiated onto the recording medium 112, and a part of the irradiation light is reflected on the surface of the recording medium 112, that is, the surface of the photoresist. Beam splitter 10
Return to 7. A part of the reflected light is reflected by the beam splitter 107 at a substantially right angle, is condensed by the lens 110, and is reflected by the CCD.
An image is formed on the light receiving surface of the camera 111. At this time, the light receiving surface of the CCD camera 111 and the recording medium 112 are arranged so as to be confocal. The recording medium 112 is formed by applying a photosensitive material film such as a photoresist with a film thickness of about 50 to 100 nm on the surface of a glass substrate such as a transparent circular glass plate. The photosensitive material film is sensitive to recording light having a wavelength of 351 nm emitted from an argon ion laser, and is not sensitive to He—Ne laser light having a wavelength of 633 nm.
【００６０】上記した構成を用いて、以下に述べる２つ
の焦点制御方法が実施されている。第１の焦点制御方法
は、対物レンズ１１７の焦点位置が記録媒体１１２にお
ける感光材料膜の表面から内部へ向かって厚み方向に感
光材料膜の膜厚より少ない所定の微少距離だけ変位した
状態に対物レンズの焦点制御を実行する。上記した所定
の微少距離は、ピットを精度よく形成するために、また
フォーカス残差に起因して焦点位置が変動しても焦点位
置が感光材料膜から外に出ないようにするために、感光
材料膜の膜厚の略１／３から略２／３の範囲の値が好ま
しく、感光材料膜の膜厚の略１／２の値が最も好まし
い。The following two focus control methods are implemented by using the above-mentioned structure. In the first focus control method, the objective is moved to a state in which the focal position of the objective lens 117 is displaced inward from the surface of the photosensitive material film on the recording medium 112 by a predetermined minute distance smaller than the film thickness of the photosensitive material film in the thickness direction. Executes focus control of the lens. The above-mentioned predetermined minute distance is set in order to form pits with high accuracy and to prevent the focus position from moving out of the photosensitive material film even if the focus position changes due to the focus residual. A value in the range of about 1/3 to about 2/3 of the film thickness of the material film is preferable, and a value of about 1/2 of the film thickness of the photosensitive material film is most preferable.
【００６１】また、第２の焦点制御方法は、記録光より
も波長が長い別の光を用いて対物レンズ１１７と記録媒
体１１２の距離を一定とするフィードバック制御を行
い、かつ記録光が記録媒体１１２によって反射された反
射光を使って対物レンズ１１７と記録媒体１１２の距離
と所望の距離とのずれを検出し、検出したずれに基づい
て対物レンズ１１７と記録媒体１１２の距離が所望の距
離になるようにフィードバック制御の制御目標位置を補
正する。In the second focus control method, feedback control is performed to make the distance between the objective lens 117 and the recording medium 112 constant by using another light having a wavelength longer than that of the recording light, and the recording light is used as the recording medium. A deviation between the distance between the objective lens 117 and the recording medium 112 and a desired distance is detected using the reflected light reflected by 112, and the distance between the objective lens 117 and the recording medium 112 is set to the desired distance based on the detected deviation. The control target position of the feedback control is corrected so that
【００６２】さらに、第１の焦点制御方法に第２の焦点
制御方法を組み合わせてもよい。Further, the second focus control method may be combined with the first focus control method.
【００６３】さらに、上記第１および第２の焦点制御方
法を、情報記録媒体原盤を作成するための情報記録媒体
原盤作成方法に適用することもできる。Furthermore, the first and second focus control methods described above can also be applied to an information recording medium master disk manufacturing method for manufacturing an information recording medium master disk.
【００６４】図２は、本実施例における情報記録媒体原
盤作成装置に含まれる、焦点制御装置の部分ならびに、
焦点位置ずれ検出装置の部分の具体的な構成を示す概略
図であり、この図を参照しながら焦点制御方法および焦
点位置ずれ検出方法、ならびに情報記録媒体原盤作成方
法について具体的に説明する。FIG. 2 shows a portion of the focus control device included in the information recording medium master disc forming apparatus according to this embodiment, and
FIG. 3 is a schematic diagram showing a specific configuration of a portion of a focus position shift detection device, and a focus control method, a focus position shift detection method, and an information recording medium master disc forming method will be specifically described with reference to this figure.
【００６５】図２において、ビームスプリッタ２０１、
平凸レンズ２０２、ＣＣＤカメラ２０３、第１の２色性
ミラー２０４、第２の２色性ミラー２０５、アクチュエ
ータ２１９付の対物レンズ２０６、記録媒体２０７は、
各々図１のビームスプリッタ１０７、平凸レンズ１１
０、ＣＣＤカメラ１１１、第１の２色性ミラー１１５、
第２の２色性ミラー１１６、アクチュエータ１１８付の
対物レンズ１１７、記録媒体１１２に対応している。ま
た、光源を含む斜め入射光学系２０８および２分割フォ
トダイオード２０９は、図１の焦点制御光学系１１４に
対応する。In FIG. 2, the beam splitter 201,
The plano-convex lens 202, the CCD camera 203, the first dichroic mirror 204, the second dichroic mirror 205, the objective lens 206 with the actuator 219, and the recording medium 207 are
The beam splitter 107 and the plano-convex lens 11 of FIG.
0, CCD camera 111, first dichroic mirror 115,
It corresponds to the second dichroic mirror 116, the objective lens 117 with the actuator 118, and the recording medium 112. The oblique incidence optical system 208 including the light source and the two-divided photodiode 209 correspond to the focus control optical system 114 in FIG.
【００６６】この情報記録媒体原盤作成装置において
は、移動光学台２１８上には、波長６３３ｎｍのＨｅ−
Ｎｅレーザー光源を搭載した斜め入射光学系２０８が配
されている。斜め入射光学系２０８のＨｅ−Ｎｅレーザ
ー光源から出た波長６３３ｎｍのレーザー光は、第１の
２色性ミラー２０４および第２の２色性ミラー２０５で
反射され、アクチュエータ２１９が設けられた対物レン
ズ２０６を通して円形のガラス盤にフォトレジスト（感
光性材料膜）を塗布した記録媒体２０７に照射される。In this information recording medium master disk forming apparatus, He-having a wavelength of 633 nm is placed on the moving optical table 218.
An oblique incidence optical system 208 equipped with a Ne laser light source is arranged. The laser light having a wavelength of 633 nm emitted from the He-Ne laser light source of the oblique incidence optical system 208 is reflected by the first dichroic mirror 204 and the second dichroic mirror 205, and the objective lens provided with the actuator 219 is provided. A recording medium 207, which is a circular glass plate coated with a photoresist (photosensitive material film), is irradiated through 206.
【００６７】この際、フォトレジストには、上述したよ
うに波長６３３ｎｍの光に対して感度が無いものを選定
する。照射された光の一部は、記録媒体２０７で反射し
て、同じ光路を通って、斜め入射光学系２０８に戻り、
受光面が２分割されたフォトダイオード２０９に入射す
る。At this time, as the photoresist, one which is not sensitive to the light having the wavelength of 633 nm is selected as described above. A part of the irradiated light is reflected by the recording medium 207, passes through the same optical path, and returns to the oblique incidence optical system 208.
The light is incident on the photodiode 209 whose light receiving surface is divided into two.
【００６８】斜め入射法とは、対物レンズ２０６に対し
て光軸を垂直から傾けて光を入射させることにより、対
物レンズ２０６と記録媒体２０７の距離が変化した際、
光軸が左右あるいは上下に変化することを利用して、両
者間の距離の変化を検出する方法である。The oblique incidence method means that when the distance between the objective lens 206 and the recording medium 207 is changed by injecting light with the optical axis inclined to the objective lens 206 from the vertical,
This is a method of detecting the change in the distance between the two by utilizing the fact that the optical axis changes from side to side or up and down.
【００６９】ここで、斜め入射法、いわゆるスキュー法
について、図４を参照しながら説明する。スキュー法で
は、以下のようにして、対物レンズ２と基板１との距離
の変化を検出する。すなわち、図４に示すように、対物
レンズ２に対し、光軸４を傾けて光を入射させ、対物レ
ンズ２を透過した光が、基板１で反射されて再び対物レ
ンズ２を透過させるようにする。そして、対物レンズ２
を再び透過した光を、受光面が２分割されたディテクタ
３で受けるようにする。このときに、ディテクタ３の２
つの受光面からの信号の差を用いて、対物レンズ２と基
板１との距離の変化を検出する。Here, the oblique incidence method, so-called skew method will be described with reference to FIG. In the skew method, the change in the distance between the objective lens 2 and the substrate 1 is detected as follows. That is, as shown in FIG. 4, the optical axis 4 is inclined with respect to the objective lens 2 so that the light is incident, and the light transmitted through the objective lens 2 is reflected by the substrate 1 and transmitted through the objective lens 2 again. To do. And the objective lens 2
The light that has been transmitted again is received by the detector 3 whose light-receiving surface is divided into two. At this time, 2 of the detector 3
The change in the distance between the objective lens 2 and the substrate 1 is detected by using the difference between the signals from the two light receiving surfaces.
【００７０】図４の（ｂ）に示される状態がディテクタ
３の受光面の分割線と反射光の光軸４とが一致する状態
であるとすると、同図の（ａ）の状態のように、同図の
（ｂ）の状態に比べて基板１が遠ざかった場合、反射光
の光軸が傾き、２つの受光面からの信号の差に変化が生
じ、これによって対物レンズ２と基板１との距離の変化
の大きさおよび方向が検出される。Assuming that the state shown in FIG. 4B is a state in which the dividing line of the light receiving surface of the detector 3 and the optical axis 4 of the reflected light coincide with each other, as shown in the state of FIG. , The optical axis of the reflected light is tilted when the substrate 1 is farther than in the state of (b) in the figure, and the difference between the signals from the two light receiving surfaces is changed, whereby the objective lens 2 and the substrate 1 are separated. The magnitude and direction of the change in the distance is detected.
【００７１】また、同図の（ｃ）の状態のように、同図
の（ｂ）の状態に比べて基板１が近づいた場合、反射光
の光軸が同図の（ａ）の場合と逆方向に傾き、２つの受
光面からの信号の差に同図（ａ）の場合とは正負の極性
が逆転した変化が生じ、これによって対物レンズ２と基
板１との距離の変化の大きさおよび方向が検出される。Further, as in the state of (c) in the figure, when the substrate 1 is closer than in the state of (b) in the figure, when the optical axis of the reflected light is in the case of (a) in the figure. The difference between the signals from the two light-receiving surfaces is tilted in the opposite direction, and the positive and negative polarities are reversed from those in the case of FIG. 3A, and this causes the magnitude of the change in the distance between the objective lens 2 and the substrate 1. And the direction is detected.
【００７２】本実施例では、対物レンズ２と基板１との
距離が変化した際、反射光がフォトダイオード２０９の
受光面上を水平方向に移動するよう調整されている。そ
して、フォトダイオード２０９は、２分割された受光面
が、水平方向に並ぶように配置されている。その結果、
対物レンズ２０６と記録媒体２０７との両者の距離が変
化した場合、フォトダイオード２０９における左右それ
ぞれの受光面からの出力が変化する。In this embodiment, when the distance between the objective lens 2 and the substrate 1 changes, the reflected light is adjusted to move horizontally on the light receiving surface of the photodiode 209. The photodiode 209 is arranged such that the light-receiving surfaces divided into two are arranged in the horizontal direction. as a result,
When the distance between the objective lens 206 and the recording medium 207 changes, the outputs from the left and right light receiving surfaces of the photodiode 209 change.
【００７３】フォトダイオード２０９の左右それぞれの
受光面からの出力は、第１のプリアンプ２１０と第２の
プリアンプ２１１によりそれぞれ増幅され、第１の差動
増幅アンプ２１２により、差動増幅される。これによ
り、２分割フォトダイオード２０９の受光面上での左右
方向の光軸変化が、正負の電気信号に変換される。第１
の差動増幅アンプ２１２の出力は、第２の差動増幅アン
プ２１３を介して、電流駆動回路２１４に入力され、対
物レンズ２０６に付帯のアクチュエータ２１９を駆動す
る。The outputs from the left and right light receiving surfaces of the photodiode 209 are amplified by the first preamplifier 210 and the second preamplifier 211, respectively, and differentially amplified by the first differential amplifier 212. As a result, a change in the optical axis in the left-right direction on the light-receiving surface of the two-divided photodiode 209 is converted into a positive / negative electric signal. First
The output of the differential amplification amplifier 212 is input to the current drive circuit 214 via the second differential amplification amplifier 213, and drives the actuator 219 attached to the objective lens 206.
【００７４】この回路系は、情報記録媒体原盤作成装置
あるいは焦点制御装置における焦点制御のためのフィー
ドバック制御ループ、つまりフィードバック制御手段を
形成し、第２の差動増幅アンプ２１３の出力が０になる
ように働く。そのため、第２の差動増幅アンプ２１３へ
の他方の入力値を変化させることで、第１の差動増幅ア
ンプ２１２の出力値の制御目標値を変えることが可能で
ある。それは、すなわち対物レンズ２０６と記録媒体２
０７の距離の制御目標値を変えるということになる。さ
らに、６３３ｎｍという記録光よりも波長の長い光を用
いてフィードバック制御を行うため、２分割フォトダイ
オード２０９において、良好なＳ／Ｎ比が得られ、安定
したフィードバック制御が行える。This circuit system forms a feedback control loop for focus control in the information recording medium master disc forming apparatus or the focus control apparatus, that is, feedback control means, and the output of the second differential amplifier 213 becomes zero. Work like. Therefore, by changing the other input value to the second differential amplification amplifier 213, it is possible to change the control target value of the output value of the first differential amplification amplifier 212. That is, the objective lens 206 and the recording medium 2
This means changing the control target value of the distance of 07. Further, since feedback control is performed using light having a wavelength of 633 nm, which is longer than the recording light, a good S / N ratio can be obtained in the two-divided photodiode 209, and stable feedback control can be performed.
【００７５】一方、記録光は、ビームスプリッタ２０１
を一部透過して、第１の２色性ミラー２０４を透過し、
第２の２色性ミラー２０５で反射されてアクチュエータ
２１９付きの対物レンズ２０６で集光され、記録媒体２
０７に照射される。その一部は、記録媒体２０７の表
面、すなわち、フォトレジストの表面で反射され、第２
の２色性ミラー２０５と第１の２色性ミラー２０４を介
してビームスプリッタ２０１により一部が反射される。
ビームスプリッタ２０１により反射された光は、平凸レ
ンズ２０２によって集光され、ＣＣＤカメラ２０３の受
光面上に達し、記録媒体２０７上での記録光のスポット
形状が結像する。On the other hand, the recording light is reflected by the beam splitter 201.
Through a portion of the first dichroic mirror 204,
The light is reflected by the second dichroic mirror 205 and condensed by the objective lens 206 with the actuator 219, and the recording medium 2
It is irradiated at 07. A part thereof is reflected on the surface of the recording medium 207, that is, the surface of the photoresist, and the second
Part of the light is reflected by the beam splitter 201 via the dichroic mirror 205 and the first dichroic mirror 204.
The light reflected by the beam splitter 201 is condensed by the plano-convex lens 202, reaches the light receiving surface of the CCD camera 203, and the spot shape of the recording light on the recording medium 207 forms an image.
【００７６】以上の構成が、情報記録媒体原盤作成装置
あるいは焦点制御装置において、記録光が記録媒体２０
７の表面で反射された反射光を用いて対物レンズ２０６
と記録媒体２０７の距離と所望の距離とのずれを検出す
る位置検出手段となる。また焦点位置ずれ検出装置にお
いて、受光面に入射する光の強度分布を検出する受光手
段となり、記録する情報に応じて変調される記録光が対
物レンズ２０６を通して記録媒体２０７で反射された反
射光の強度分布を検出する。この際、受光手段は、受光
面と記録媒体２０７が共焦点となるように配され、反射
光の強度分布として受光面に映る反射光のスポットの強
度分布を検出することになる。With the above configuration, in the information recording medium master disc forming apparatus or the focus control apparatus, the recording light is emitted from the recording medium 20.
The objective lens 206 using the reflected light reflected by the surface of No. 7
And position detecting means for detecting a deviation between the distance of the recording medium 207 and a desired distance. Further, in the focus position shift detecting device, it becomes a light receiving means for detecting the intensity distribution of the light incident on the light receiving surface, and the recording light modulated according to the information to be recorded is reflected by the recording medium 207 through the objective lens 206. Detect the intensity distribution. At this time, the light receiving means is arranged so that the light receiving surface and the recording medium 207 are confocal, and detects the intensity distribution of the spot of the reflected light reflected on the light receiving surface as the intensity distribution of the reflected light.
【００７７】対物レンズ２０６と記録媒体２０７の距離
を変化させた時に、ＣＣＤカメラ２０３で映し出される
記録光のスポット形状を図３を参照して説明し、本発明
の焦点位置ずれ検出方法を図２を参照しながら説明す
る。The spot shape of the recording light projected by the CCD camera 203 when the distance between the objective lens 206 and the recording medium 207 is changed will be described with reference to FIG. 3, and the focus position deviation detecting method of the present invention will be described with reference to FIG. Will be described with reference to.
【００７８】この焦点位置ずれ検出方法は、記録される
情報に応じて変調される記録光が対物レンズを通して記
録媒体で反射された反射光の強度分布から、対物レンズ
と記録媒体の距離と所望の距離とのずれを検出する。具
体的には、記録媒体と共焦点となるように配置された受
光面に映る反射光のスポット内の中心の強度と、スポッ
トの中心と回折リングの強度が最大となる点との距離と
から対物レンズと記録媒体の距離と所望の距離とのずれ
を検出する。もしくは、スポット内の中心の強度と、ス
ポットの回折リングの強度とから、対物レンズと記録媒
体の距離と所望の距離とのずれを検出する。In this focus position shift detection method, the distance between the objective lens and the recording medium and the desired value are calculated based on the intensity distribution of the reflected light in which the recording light modulated according to the information to be recorded is reflected by the recording medium through the objective lens. The deviation from the distance is detected. Specifically, from the intensity of the center of the spot of the reflected light reflected on the light receiving surface arranged so as to be confocal with the recording medium, and the distance between the spot center and the point where the intensity of the diffraction ring is maximum. A shift between the distance between the objective lens and the recording medium and a desired distance is detected. Alternatively, the deviation between the distance between the objective lens and the recording medium and a desired distance is detected from the strength of the center of the spot and the strength of the diffraction ring of the spot.
【００７９】対物レンズ２０６と記録媒体２０７の表面
（すなわち、フォトレジストの表面）との距離が、対物
レンズ２０６の焦点位置よりも遠い場合、円形ではある
が、ＣＣＤカメラ上のスポット径が大きく、中心の光強
度も低い（図３の（ａ）の状態）。When the distance between the objective lens 206 and the surface of the recording medium 207 (that is, the surface of the photoresist) is longer than the focal position of the objective lens 206, it is circular, but the spot diameter on the CCD camera is large, The light intensity at the center is also low (state of FIG. 3A).
【００８０】両者の距離が近づくにつれ、スポット径が
徐々に小さくなり、中心の光強度も徐々に大きくなる
（図３の（ｂ），（ｃ）の状態）。そして、記録媒体２
０７の表面が対物レンズ２０６の焦点位置となる位置で
スポットの大きさは最小となり、強度は最高となる（図
３の（ｄ）の状態）。As the distance between the two approaches, the spot diameter gradually decreases, and the light intensity at the center gradually increases (states (b) and (c) in FIG. 3). And the recording medium 2
At the position where the surface of 07 becomes the focal position of the objective lens 206, the size of the spot becomes minimum and the intensity becomes maximum (state (d) of FIG. 3).
【００８１】両者の距離がさらに近づくと、記録媒体２
０７の表面が焦点位置から徐々に外れていき、ＣＣＤカ
メラ上のスポットに回折によるリングが現れ、中心の強
度も減少する（図３（ｅ），（ｆ），（ｇ）の状態）。
この時、回折リングのピークの位置と分布の中心との距
離δは、対物レンズ２０６と記録媒体２０７の距離が近
づくにつれて広くなり、回折リングの強度も低くなる。When the distance between the two is further reduced, the recording medium 2
The surface of No. 07 gradually deviates from the focal position, a ring due to diffraction appears in the spot on the CCD camera, and the intensity of the center also decreases (states of FIGS. 3E, 3F, and 3G).
At this time, the distance δ between the position of the peak of the diffraction ring and the center of the distribution becomes wider as the distance between the objective lens 206 and the recording medium 207 becomes shorter, and the intensity of the diffraction ring also becomes lower.
【００８２】記録媒体２０７が所定の厚さのフォトレジ
ストを塗布したガラス盤であり、フォトレジストを露光
・現像して微細なピットを精度よく形成するためには、
対物レンズ２０６と記録媒体２０７の距離は、以下のよ
うに設定することが望ましい。すなわち、フォトレジス
トの膜厚を考慮すると、記録光の焦点が記録媒体２０７
のフォトレジストの表面でちょうど合う距離よりも、フ
ォトレジストの厚み方向の中間位置で合う距離の方が好
ましい。言い換えると、焦点位置がフォトレジストの内
部に向かってずれていることが好ましい。数値的には、
フォトレジストの表面からその膜厚の１／３の位置から
膜厚の２／３の位置までの範囲に焦点が位置することが
好ましい。さらに好ましくは、フォトレジストの表面か
らその膜厚のほぼ１／２の位置に焦点が位置するが最適
である。図３で言えば、たとえば（ｅ）の状態に調整さ
れるのが望ましい。The recording medium 207 is a glass disk coated with a photoresist having a predetermined thickness, and in order to precisely form fine pits by exposing and developing the photoresist,
The distance between the objective lens 206 and the recording medium 207 is preferably set as follows. That is, considering the film thickness of the photoresist, the focus of the recording light is the recording medium 207.
It is preferable that the distance at the intermediate position in the thickness direction of the photoresist is more than that at the surface of the photoresist. In other words, it is preferable that the focus position is shifted toward the inside of the photoresist. Numerically,
It is preferable that the focal point be located in the range from the surface of the photoresist to the position of ⅓ of the film thickness to the position of ⅔ of the film thickness. More preferably, the focal point is optimally located at a position approximately 1/2 of the film thickness of the photoresist surface. In terms of FIG. 3, it is desirable to adjust to the state of (e), for example.
【００８３】ここで、記録光の焦点位置がフォトレジス
トの内部に向かってずらすことが好ましい理由につい
て、図５および図６を参照しながら説明する。The reason why it is preferable to shift the focal position of the recording light toward the inside of the photoresist will be described with reference to FIGS. 5 and 6.
【００８４】上記の理由を記録されるピットのサイズ
と、制御目標位置のオフセットとの関係で、以下に説明
する。The above reason will be described below in relation to the size of the pit to be recorded and the offset of the control target position.
【００８５】図５に示すように、対物レンズ１１により
集光された記録光Ａの焦点位置と、ガラス基材（ガラス
盤）１３上に形成された感光材料膜（フォトレジスト）
１２の位置関係において、焦点Ｐが感光材料膜１２の厚
み方向の略中心にある（ｂ）の状態の場合、現像後に形
成されるピット１２ｂの幅は最小となり、微細なピット
を精度よく形成することができる。ところが、焦点Ｐが
感光材料膜１の略表層にある（ａ）の状態、あるいは、
焦点Ｐが感光材料膜１２とガラス基材１３の略界面に位
置する（ｃ）の状態の場合には、感光材料膜２内におけ
る集光された記録光の平均的な大きさが大きくなるた
め、現像後に形成されるピット１２ａ，１２ｃの幅は
（ｂ）の状態で形成されるピット１２ｂに比べ幅が大き
くなり、微細なピットを精度よく形成することが容易で
ない。As shown in FIG. 5, the focal position of the recording light A focused by the objective lens 11 and the photosensitive material film (photoresist) formed on the glass substrate (glass disk) 13 are formed.
In the positional relationship of 12, when the focus P is in the state of (b) which is substantially in the center of the photosensitive material film 12 in the thickness direction, the width of the pit 12b formed after the development becomes the minimum, and a fine pit is accurately formed. be able to. However, in the state of (a) where the focus P is on the substantially surface layer of the photosensitive material film 1, or
In the case of the state (c) in which the focal point P is located substantially at the interface between the photosensitive material film 12 and the glass substrate 13, the average size of the recording light condensed in the photosensitive material film 2 becomes large. The width of the pits 12a and 12c formed after development is larger than that of the pit 12b formed in the state of (b), and it is not easy to form fine pits with high precision.
【００８６】また、焦点制御された状態においても、フ
ィードバック制御系のゲインで決まる残差（一般的に言
われるフォーカス残差）が残り、その範囲で焦点制御位
置は常に変動している。Even in the focus-controlled state, a residual error (generally called focus residual error) determined by the gain of the feedback control system remains, and the focus control position constantly fluctuates in that range.
【００８７】図６は、焦点の位置がそれぞれ感光材料膜
の略表層、感光材料膜の略中心、および感光材料膜とガ
ラス基材との略界面にある場合において、フォーカス残
差に起因したピットの大きさの変化を示す模式図であ
る。同図（ａ）はガラス基材上の記録位置とガラス基材
および対物レンズの距離との関係を示し、曲線Ｘはフォ
ーカス残差によりガラス基材と対物レンズとの距離が記
録光のガラス基材上の位置によって変化していることを
示している。直線Ｙはガラス基材と対物レンズとの平均
距離を示している。同図（ａ）において、記号Ｚは、感
光材料膜の厚みに相当する幅を示している。FIG. 6 shows pits resulting from focus residuals when the focal points are located at the approximate surface layer of the photosensitive material film, the approximate center of the photosensitive material film, and the approximate interface between the photosensitive material film and the glass substrate. It is a schematic diagram which shows the change of the size of. FIG. 3A shows the relationship between the recording position on the glass substrate and the distance between the glass substrate and the objective lens, and the curve X indicates the distance between the glass substrate and the objective lens due to the focus residual and the glass substrate of the recording light. It shows that it changes depending on the position on the material. The straight line Y indicates the average distance between the glass substrate and the objective lens. In FIG. 4A, the symbol Z indicates the width corresponding to the thickness of the photosensitive material film.
【００８８】同図（ｂ）は焦点の位置が感光材料膜の略
表層にある場合において、形成されるピットの大きさの
変化を示している。同図（ｃ）は、焦点の位置が感光材
料膜の略中心にある場合において、形成されるピットの
大きさの変化を示している。FIG. 11B shows the change in the size of the pits formed when the focal point is located substantially on the surface layer of the photosensitive material film. FIG. 6C shows the change in the size of the pits formed when the focal point is located substantially at the center of the photosensitive material film.
【００８９】同図（ｄ）は焦点の位置が感光材料膜とガ
ラス基材との略界面にある場合において、形成されるピ
ットの大きさの変化を示している。FIG. 9D shows the change in the size of the pits formed when the focal point is located substantially at the interface between the photosensitive material film and the glass substrate.
【００９０】同図（ｂ）においては、対物レンズとの距
離が遠くなる側で、焦点位置が感光材料膜外へ出て、集
光された記録光の平均的な大きさが増すため、ピットが
大きくなる。逆に、同図（ｄ）においては、対物レンズ
との距離が近くなる側で、焦点位置が感光材料膜外へ出
て、集光された記録光の平均的な大きさが増すため、ピ
ットが大きくなる。同図（ｃ）においては、フォーカス
残差の変動内において、常に焦点位置が感光材料膜の略
中心を保つことから、一定の安定した大きさのピットが
形成される。In the same figure (b), the focus position goes out of the photosensitive material film on the side farther from the objective lens, and the average size of the condensed recording light increases, so that the pit Grows larger. On the other hand, in the figure (d), on the side closer to the objective lens, the focus position goes out of the photosensitive material film and the average size of the condensed recording light increases, so that the pit Grows larger. In the same figure (c), since the focus position always keeps substantially the center of the photosensitive material film within the fluctuation of the focus residual, pits of a constant and stable size are formed.
【００９１】ここで、微細なピットを精度よく形成し、
またフォーカス残差による焦点位置の変動にかかわら
ず、記録されるピット形状あるいは大きさの変化を少な
くするためには、記録光の焦点を感光性材料膜の表面か
ら感光性材料膜の膜厚の１／３から２／３までの範囲に
するのが好ましい。さらには、記録光の焦点を感光性材
料膜の厚み方向の略中心（１／２）にするのが最も望ま
しい。Here, fine pits are accurately formed,
In order to reduce the change in the recorded pit shape or size regardless of the change in the focus position due to the focus residual, the focus of the recording light is changed from the surface of the photosensitive material film to the film thickness of the photosensitive material film. It is preferably in the range of 1/3 to 2/3. Furthermore, it is most desirable that the focal point of the recording light is approximately the center (1/2) in the thickness direction of the photosensitive material film.
【００９２】ここで、ピットの寸法について、数値的に
説明する。上記の記録媒体原盤をもとに作成される光デ
ィスクは、例えばポリカーボネートの表面にスタンパに
よって原盤に形成したピットを複製することになる。複
製された光ディスクでは、ピットの内側の反射光とピッ
トの外側の反射光の干渉による反射光の打ち消し作用に
よる反射光の強度変化を利用してトラッキングサーボ等
が行われる。このときに反射光の打ち消しのために必要
な位相差を得るためのピットの深さＰは、再生用レーザ
ー光の波長をλ、屈折率をｎとしたときに、例えば、
（１／８）・λ／ｎから（１／４）・λ／ｎの範囲に設
定される。再生用レーザー光の波長を例えば６５０ｎｍ
とし、ポリカーボネートの屈折率ｎを１．５とすると、
ピットの深さＰは５０〜１００ｎｍとなる。一方、ピッ
トの幅は、例えば０．１〜０．５μｍ±０．０１μｍで
あり、その長さは例えば０．１〜３μｍ程度である。な
お、ピットではなく連続した溝の場合もある。その場合
の幅はピットの幅の同じである。Here, the dimensions of the pits will be described numerically. An optical disk produced based on the above-mentioned recording medium master copy duplicates the pits formed on the master by a stamper on the surface of polycarbonate, for example. In the duplicated optical disc, tracking servo or the like is performed by utilizing the intensity change of the reflected light due to the canceling action of the reflected light due to the interference of the reflected light inside the pit and the reflected light outside the pit. At this time, the depth P of the pit for obtaining the phase difference necessary for canceling the reflected light is, for example, when the wavelength of the reproducing laser light is λ and the refractive index is n,
It is set in the range of (1/8) · λ / n to (1/4) · λ / n. The wavelength of the reproduction laser light is, for example, 650 nm
And the refractive index n of the polycarbonate is 1.5,
The pit depth P is 50 to 100 nm. On the other hand, the width of the pit is, for example, 0.1 to 0.5 μm ± 0.01 μm, and the length thereof is, for example, about 0.1 to 3 μm. In some cases, the groove is not a pit but a continuous groove. In that case, the width is the same as the width of the pit.
【００９３】このように、ピットの深さは、ピットの幅
に比べ１／１０〜１／３程度であり、ピットの幅に比べ
て無視できる値ではない。そのため、原盤形成時におい
て、記録光の焦点位置が、フォトレジストの表面、略中
心、ガラス基材との略界面のように異なることによる記
録光の大きさの変化が、ピットの幅に大きな影響を与え
ることになる。そこで、上述したように、記録光の平均
的直径をできるだけ小さくできる位置に焦点位置をもっ
てくることがピットを精度よく形成する上で有効とな
る。As described above, the pit depth is about 1/10 to 1/3 of the pit width, which is not a negligible value compared to the pit width. Therefore, when the master disk is formed, the focus position of the recording light is different, such as the photoresist surface, the center, and the interface with the glass substrate. Will be given. Therefore, as described above, it is effective to bring the focal point to a position where the average diameter of the recording light can be made as small as possible in order to form pits with high accuracy.
【００９４】上述したスポット形状から対物レンズ２０
６と記録媒体２０７の距離の理想値とのずれを検出する
ためには、まず、ＣＣＤカメラ２０３の出力を走査線信
号抽出回路２１５に入力し、スポットが結像した周辺で
強度が最大となる走査線を抽出することで、結像された
スポット形状の中心を通る走査線を抽出する。From the spot shape described above, the objective lens 20
In order to detect the deviation of the distance between the recording medium 207 and the recording medium 207 from the ideal value, first, the output of the CCD camera 203 is input to the scanning line signal extraction circuit 215, and the intensity becomes maximum in the periphery where the spot is imaged. By extracting the scanning line, the scanning line passing through the center of the imaged spot shape is extracted.
【００９５】具体的に説明すると、ＣＣＤカメラ２０３
に例えば図７（ａ）に示すようなスポットの画像２０が
得られた場合に、各走査線毎に画像信号を抽出し、それ
をＡ／Ｄ変換する。例えば、スポットの周辺部を通る走
査線２１では、同図（ｂ）に示すような映像信号が得ら
れ、スポットの中心部を通る走査線２２では、同図
（ｃ）に示すように映像信号が得られ、スポットの外側
を通る走査線２３では、同図（ｄ）に示すような映像信
号が得られる。これらの信号がＡ／Ｄ変換されることに
なる。そして、デジタル化された画像信号のレベルを各
走査線毎に検出することによって、信号レベルのピーク
値が最大となっている１本の走査線を抽出する。More specifically, the CCD camera 203
When, for example, an image 20 of a spot as shown in FIG. 7A is obtained, an image signal is extracted for each scanning line and A / D converted. For example, in the scanning line 21 passing through the peripheral portion of the spot, a video signal as shown in FIG. 7B is obtained, and in the scanning line 22 passing through the central portion of the spot, the video signal as shown in FIG. The scanning line 23 passing outside the spot gives a video signal as shown in FIG. These signals will be A / D converted. Then, by detecting the level of the digitized image signal for each scanning line, one scanning line having the maximum signal level peak value is extracted.
【００９６】つぎに、焦点ずれ検出回路２１６では、Ｃ
ＰＵ等による信号処理によって、抽出された走査線の最
大値強度を検出し、予め設定された最大値と比較し、最
大値よりも弱い場合、回折リングのピークの有無を検出
する。もし、回折リングが無い場合、対物レンズ２０６
と記録媒体２０７の距離が遠いと判断する。もし、回折
リングがある場合、そのピークとスポットの中心との距
離δを検出して、予め設定した規定値と比較し、その上
で、検出した距離δが規定値よりも遠い場合は、対物レ
ンズ２０６と記録媒体２０７の距離が近いと判断し、規
定値よりも近い場合は、所望の距離にあると判断する。Next, in the defocus detection circuit 216, C
The maximum intensity of the extracted scanning line is detected by signal processing by PU or the like, compared with a preset maximum value, and if weaker than the maximum value, the presence or absence of a peak of the diffraction ring is detected. If there is no diffraction ring, the objective lens 206
It is determined that the recording medium 207 is far. If there is a diffraction ring, the distance δ between the peak and the center of the spot is detected and compared with a preset specified value, and if the detected distance δ is further than the specified value, the objective It is determined that the distance between the lens 206 and the recording medium 207 is short, and if the distance is shorter than the specified value, it is determined that the distance is the desired distance.
【００９７】なお、上記の走査線の最大値強度は、抽出
した走査線における信号レベルのピーク値を検出するこ
とで求めることができる。また、上記の距離δは、抽出
された走査線の画像信号において、信号レベルのピーク
タイミング（スポットの中心に相当する）と、それに隣
接した極大値が生じるタイミング（回折リングの中心に
相当する）を検出し、両タイミングの間の時間を測定す
ることで求めることができる。回折リングの有無は、極
大値の有無を検出することによって検出できる。The maximum intensity of the scanning line can be obtained by detecting the peak value of the signal level on the extracted scanning line. Further, the distance δ is the peak timing of the signal level (corresponding to the center of the spot) and the timing at which a maximum value adjacent thereto occurs (corresponding to the center of the diffraction ring) in the image signal of the extracted scanning line. Can be obtained and the time between both timings can be measured. The presence or absence of the diffraction ring can be detected by detecting the presence or absence of the maximum value.
【００９８】また、回折リングのピークとスポットの中
心との距離δを検出する代わりに、回折リングのピーク
の強度を予め設定した規定値と比較して、弱い場合には
対物レンズ２０６と記録媒体２０７の距離が近いと判断
し、規定値よりも大きい場合は、所望の距離にあると判
断することもできる。Further, instead of detecting the distance δ between the peak of the diffraction ring and the center of the spot, the intensity of the peak of the diffraction ring is compared with a preset specified value. It is also possible to judge that the distance of 207 is short, and if it is larger than the specified value, it can be judged that it is at the desired distance.
【００９９】なお、回折リングのピークの強度は、抽出
された走査線の画像信号において、信号レベルのピーク
に隣接した極大値のレベルを検出することで求めること
ができる。The peak intensity of the diffraction ring can be obtained by detecting the maximum value level adjacent to the signal level peak in the image signal of the extracted scanning line.
【０１００】そして、焦点ずれ検出回路２１６で判断さ
れた遠近の信号を補正電圧発生回路２１７に入力して規
定の電圧を発生させ、第２の差動増幅アンプ２１３によ
り第１の差動増幅アンプ２１２の出力との差動をとるこ
とにより、制御目標値を変更させる。上記の遠近の信号
というのは、抽出された走査線の最大値強度と距離δあ
るいは回折リングの強度のことである。Then, the near-far signal determined by the defocus detection circuit 216 is input to the correction voltage generation circuit 217 to generate a prescribed voltage, and the second differential amplification amplifier 213 causes the first differential amplification amplifier 213 to generate a prescribed voltage. The control target value is changed by taking the differential with the output of 212. The above-mentioned near and far signals are the maximum intensity of the extracted scanning line and the distance δ or the intensity of the diffraction ring.
【０１０１】上記の走査線信号抽出回路２１５から補正
電圧発生回路２１７までが制御位置補正回路を構成して
いる。The scanning line signal extraction circuit 215 to the correction voltage generation circuit 217 constitute a control position correction circuit.
【０１０２】以上の構成が、情報記録媒体原盤作成装置
あるいは焦点制御装置において、位置検出手段により検
出されたずれに基づいて対物レンズ２０６と記録媒体２
０７の距離が所望の距離になるようにフィードバック制
御手段の制御目標位置を補正する制御位置補正手段とな
る。また、焦点ずれ検出回路２１６までの構成が焦点位
置ずれ検出装置において、受光手段で検出された光の強
度分布を判別する判別手段となり、検出された反射光の
強度分布を判別手段で判別することにより、対物レンズ
２０６と記録媒体２０７の距離と所望の距離とのずれを
検出する。この際、判別手段は、スポット内の中心の強
度と、スポットの中心と回折リングの強度が最大となる
点の距離とを判別するか、もしくは、スポット内の中心
の強度と、前記スポットの回折リングの強度とを判別す
ることにより、対物レンズ２０６と記録媒体２０７の距
離と所望の距離とのずれを検出する。In the above-described structure, the objective lens 206 and the recording medium 2 are based on the deviation detected by the position detecting means in the information recording medium master disc forming apparatus or the focus control apparatus.
The control position correction means corrects the control target position of the feedback control means so that the distance 07 becomes a desired distance. Further, in the focus position shift detecting device, the structure up to the focus shift detecting circuit 216 serves as a discriminating means for discriminating the intensity distribution of the light detected by the light receiving means, and discriminating the intensity distribution of the detected reflected light by the discriminating means. Thus, the deviation between the distance between the objective lens 206 and the recording medium 207 and the desired distance is detected. At this time, the discriminating means discriminates between the intensity of the center of the spot and the distance between the center of the spot and the point where the intensity of the diffraction ring is maximum, or the intensity of the center of the spot and the diffraction of the spot. By discriminating the strength of the ring, a deviation between the desired distance and the distance between the objective lens 206 and the recording medium 207 is detected.
【０１０３】また、第２の差動増幅アンプ２１３を使う
代わりに、補正電圧発生回路２１７の出力を第１の差動
増幅アンプ２１２のオフセット調整端子に入力すること
でも、上記と同様の効果が得られる。Further, instead of using the second differential amplification amplifier 213, the same effect as above can be obtained by inputting the output of the correction voltage generation circuit 217 to the offset adjustment terminal of the first differential amplification amplifier 212. can get.
【０１０４】この発明により、記録中も常に対物レンズ
２０６と記録媒体２０７の距離を所望の距離に制御する
ことが可能となる。焦点制御位置の変化は、時間的に遅
い変化であり、これら制御位置補正は、あくまで長波長
の光を使ったフィードバック制御の補助的作用を行うも
のであり、フィードバック制御の周波数特性に悪影響を
与えないようにするため１Ｈｚ以下の遅い周期で行うの
が望ましい。According to the present invention, it is possible to always control the distance between the objective lens 206 and the recording medium 207 to a desired distance even during recording. The change of the focus control position is a slow change with time, and these control position corrections are just to perform an auxiliary action of the feedback control using long wavelength light, which adversely affects the frequency characteristic of the feedback control. In order to prevent this, it is desirable to carry out at a slow cycle of 1 Hz or less.
【０１０５】本発明の実施例では、この焦点制御方法と
焦点制御装置を導入することで、安定した焦点制御を行
った上で、記録中も常に記録光の焦点位置すなわち対物
レンズ２０６と記録媒体２０７の距離を所望の距離に補
正できる情報記録媒体原盤記録方法と情報記録媒体原盤
記録装置をも実現できた。In the embodiment of the present invention, by introducing this focus control method and focus control device, stable focus control is performed, and the focus position of the recording light, that is, the objective lens 206 and the recording medium are always maintained during recording. An information recording medium master recording method and an information recording medium master recording apparatus capable of correcting the distance 207 to a desired distance were also realized.
【０１０６】[0106]
【発明の効果】本発明の焦点制御方法、情報記録媒体原
盤作成方法、焦点制御装置または情報記録媒体原盤作成
装置によれば、対物レンズの焦点位置が感光材料膜の表
面から内部へ向かって厚み方向に感光材料膜の膜厚より
少ない所定の微少距離だけ変位した状態に対物レンズの
焦点制御を実行するので、感光材料膜中での記録光の拡
がりを少なくでき、したがって感光材料膜中での記録光
の平均的直径を小さくできる。その結果、微細なピット
を精度よく形成することが可能となる。According to the focus control method, the information recording medium master disk manufacturing method, the focus control device or the information recording medium master disk manufacturing apparatus of the present invention, the focus position of the objective lens becomes thicker from the surface of the photosensitive material film toward the inside. Since the focus control of the objective lens is executed in a state in which it is displaced by a predetermined minute distance smaller than the film thickness of the photosensitive material film, the spread of recording light in the photosensitive material film can be reduced, and therefore, The average diameter of recording light can be reduced. As a result, fine pits can be accurately formed.
【０１０７】[0107]
【０１０８】[0108]
【図１】本発明の実施例における情報記録媒体原盤の作
成方法および装置を説明するための概略図である。FIG. 1 is a schematic diagram for explaining a method and apparatus for producing an information recording medium master according to an embodiment of the present invention.
【図２】本発明の実施例における焦点制御方法を説明す
るための概略図である。FIG. 2 is a schematic diagram for explaining a focus control method according to an embodiment of the present invention.
【図３】本発明の実施例におけるＣＣＤカメラ上でのス
ポット形状変化を説明するための模式図である。FIG. 3 is a schematic diagram for explaining a spot shape change on a CCD camera in the embodiment of the present invention.
【図４】斜め入射法の原理を説明するための模式図であ
る。FIG. 4 is a schematic diagram for explaining the principle of the oblique incidence method.
【図５】記録光の焦点位置とピットの大きさの関係を示
す模式図である。FIG. 5 is a schematic diagram showing the relationship between the focal position of recording light and the size of pits.
【図６】フォーカス残差に起因したピットの大きさの変
化を示す模式図である。FIG. 6 is a schematic diagram showing a change in pit size due to a focus residual.
【図７】ＣＣＤカメラ上でのスポット形状と画像信号と
の関係を示す模式図である。FIG. 7 is a schematic diagram showing a relationship between a spot shape on a CCD camera and an image signal.
１０１ 記録光源 １０２ ミラー １０３ 光強度調整器 １０４ 光変調器 １０５ ミラー １０６ ビームエキスパンダー １０７ ビームスプリッター １０８ 平凸レンズ １０９ フォトディテクター １１０ 平凸レンズ １１１ ＣＣＤカメラ １１２ 記録媒体 １１３ 移動光学台 １１４ 斜め入射光学系 １１５ 第１の２色性ミラー １１６ 第２の２色性ミラー １１７ アクチュエータ付き対物レンズ ２０１ ビームスプリッター ２０２ 平凸レンズ ２０３ ＣＣＤカメラ ２０４ 第１の２色性ミラー ２０５ 第２の２色性ミラー ２０６ アクチュエータ付き対物レンズ ２０７ 記録媒体 ２０８ 斜め入射光学系および光源 ２０９ ２分割フォトダイオード ２１０ 第１のプリアンプ ２１１ 第２のプリアンプ ２１２ 第１の差動増幅アンプ ２１３ 第２の差動増幅アンプ ２１４ 電流駆動回路 ２１５ 走査線信号抽出回路 ２１６ 焦点ずれ検出回路 ２１７ 補正電圧発生回路 101 recording light source 102 mirror 103 Light intensity adjuster 104 Optical modulator 105 mirror 106 beam expander 107 Beam splitter 108 Plano-convex lens 109 photo detector 110 Plano-convex lens 111 CCD camera 112 recording medium 113 Moving optical table 114 Oblique incidence optical system 115 First dichroic mirror 116 Second dichroic mirror 117 Objective lens with actuator 201 beam splitter 202 Plano-convex lens 203 CCD camera 204 First dichroic mirror 205 Second dichroic mirror 206 Objective lens with actuator 207 recording medium 208 Oblique incidence optical system and light source 209 2-segment photodiode 210 First Preamp 211 Second preamplifier 212 First Differential Amplifier 213 Second differential amplifier 214 Current drive circuit 215 Scan line signal extraction circuit 216 Defocus detection circuit 217 Correction voltage generation circuit
───────────────────────────────────────────────────── フロントページの続き (58)調査した分野(Int.Cl.7，ＤＢ名) G11B 7/09 G11B 7/26 501 G02B 7/28 G02B 7/36 ─────────────────────────────────────────────────── ─── Continuation of front page (58) Fields surveyed (Int.Cl. 7 , DB name) G11B 7/09 G11B 7/26 501 G02B 7/28 G02B 7/36
Claims (12)
を、基材の表面に感光材料膜が形成された記録媒体との
距離が一定となるように焦点制御された対物レンズを通
して集光し、前記記録媒体上に情報を記録する情報記録
媒体原盤作成装置の焦点制御方法であって、 前記対物レンズの焦点位置が、前記感光材料膜の表面か
ら内部へ向かって厚み方向に、前記感光材料膜の膜厚の
略１／３から略２／３の範囲の値だけ変位した状態に前
記対物レンズの焦点制御を実行することを特徴とする焦
点制御方法。1. A recording light, which is modulated according to information to be recorded, is condensed through an objective lens whose focus is controlled so that a distance from a recording medium having a photosensitive material film formed on a surface of a substrate is constant. Then, in the focus control method of the information recording medium master disc forming apparatus for recording information on the recording medium, the focus position of the objective lens is in the thickness direction from the surface of the photosensitive material film toward the inside. A focus control method, wherein the focus control of the objective lens is executed in a state in which the material lens is displaced by a value in the range of about 1/3 to about 2/3 of the film thickness of the material film.
料膜の表面から内部へ向かって厚み方向に、前記感光材
料膜の膜厚の略１／２の値だけ変位した状態に前記対物
レンズの焦点制御を実行する請求項１記載の焦点制御方
法。2. A focus position of the objective lens is displaced in a thickness direction from a surface of the photosensitive material film toward an inside thereof by a value of about ½ of a film thickness of the photosensitive material film. The focus control method according to claim 1, wherein focus control is executed.
いて前記対物レンズと前記記録媒体の距離を一定とする
フィードバック制御を行い、かつ前記記録光が前記記録
媒体から反射された反射光を使って前記対物レンズと前
記記録媒体の距離と所望の距離とのずれを検出し、検出
したずれに基づいて前記対物レンズと前記記録媒体の距
離が所望の距離になるように前記フィードバック制御の
制御目標位置を補正することにより、前記対物レンズの
焦点制御を実行することを特徴とする請求項１記載の焦
点制御方法。3. A feedback control for making the distance between the objective lens and the recording medium constant by using another light having a wavelength longer than that of the recording light, and reflection of the recording light reflected from the recording medium. A deviation between the distance between the objective lens and the recording medium and a desired distance is detected using light, and the feedback control is performed so that the distance between the objective lens and the recording medium becomes a desired distance based on the detected deviation. The focus control method according to claim 1, wherein the focus control of the objective lens is executed by correcting the control target position of.
を、記録媒体との距離が一定となるように焦点制御され
た対物レンズを通して集光し、前記記録媒体上に情報を
記録する情報記録媒体原盤作成方法であって、 前記対物レンズの焦点位置が、前記感光材料膜の表面か
ら内部へ向かって厚み方向に、前記感光材料膜の膜厚の
略１／３から略２／３の範囲の値だけ変位した状態に前
記対物レンズの焦点制御を実行することを特徴とする情
報記録媒体原盤作成方法。 4. Recording light modulated according to information to be recorded
The focus is controlled so that the distance to the recording medium is constant.
Information through the objective lens and the information is recorded on the recording medium.
An information recording medium master recording method for recording, wherein the focus position of the objective lens is the surface of the photosensitive material film.
From the inside to the thickness direction, the thickness of the photosensitive material film
Before being displaced by a value in the range of approximately 1/3 to 2/3
Information that is characterized by executing focus control of the objective lens.
Information recording medium master disk making method.
料膜の表面から内部へ向かって厚み方向に、前記感光材
料膜の膜厚の略１／２の値だけ変位した状態に前記対物
レンズの焦点制御を実行する請求項４記載の情報記録媒
体原盤作成方法。 5. The photosensitive material has a focal position of the objective lens.
In the thickness direction from the surface of the material film to the inside, the photosensitive material
The objective is placed in a state of being displaced by a value of about ½ of the thickness of the material film.
The information recording medium according to claim 4, which executes focus control of the lens.
How to make a master disc.
いて前記対物レンズと前記記録媒体の距離を一定とする
フィードバック制御を行い、かつ前記記録光が前記記録
媒体から反射された反射光を使って前記対物レンズと前
記記録媒体の距離と所望の距離とのずれを検出し、検出
したずれに基づいて前記対物レンズと前記記録媒体の距
離が所望の距離になるように前記フィードバック制御の
制御目標位置を補正することにより、前記対物レンズの
焦点制御を実行することを特徴とする請求項４記載の情
報記録媒体原盤作成方法。 6. Another light having a wavelength longer than that of the recording light is used.
And keep the distance between the objective lens and the recording medium constant.
Feedback control is performed, and the recording light is used for the recording.
The reflected light reflected from the medium is used to
Detects and detects the deviation between the distance of the recording medium and the desired distance
The distance between the objective lens and the recording medium based on the deviation
The feedback control is performed so that the separation becomes a desired distance.
By correcting the control target position,
The information according to claim 4, characterized in that focus control is executed.
Information recording medium master disk making method.
を、記録媒体との距離が一定となるように焦点制御され
た対物レンズを通して集光し、前記記録媒体上に情報を
記録する情報記録媒体原盤作成装置に使用される焦点制
御装置であって、 前記対物レンズの焦点位置が、前記感光材料膜の表面か
ら内部へ向かって厚み方向に、前記感光材料膜の膜厚の
略１／３から略２／３の範囲の値だけ変位した状態に前
記対物レンズの焦点制御を実行する焦点制御手段を設け
たことを特徴とする焦点制御装置。 7. A recording light which is modulated according to information to be recorded.
The focus is controlled so that the distance to the recording medium is constant.
Information through the objective lens and the information is recorded on the recording medium.
Information recording medium to be recorded
A control apparatus, the focal position of the objective lens, or the surface of the photosensitive material film
From the inside to the thickness direction, the thickness of the photosensitive material film
Before being displaced by a value in the range of approximately 1/3 to 2/3
Provided with focus control means for executing focus control of the objective lens
A focus control device characterized in that
料膜の表面から内部へ向かって厚み方向に、前記感光材
料膜の膜厚の略１／２の値だけ変位した状態に前記対物
レンズの焦点制御を実行する請求項７記載の焦点制御装
置。 8. The photosensitive material is the focal position of the objective lens.
In the thickness direction from the surface of the material film to the inside, the photosensitive material
The objective is placed in a state of being displaced by a value of about ½ of the thickness of the material film.
The focus control device according to claim 7, which executes focus control of the lens.
Place
波長が長い別の光を用いて前記対物レンズと前記記録媒
体の距離を一定に保つフィードバック制御手段と、前記
記録光が前記記録媒体で反射された反射光を用いて前記
対物レンズと前記記録媒体の距離と所望の距離とのずれ
を検出する位置検出手段と、前記位置検出手段により検
出されたずれに基づいて前記対物レンズと前記記録媒体
の距離が所望の距離になるように前記フィードバック制
御手段の制御目標位置を補正する制御位置補正手段とか
らなる請求項７記載の焦点制御装置。 9. The focus control means is better than the recording light.
The objective lens and the recording medium are formed by using another light having a long wavelength.
Feedback control means for maintaining a constant body distance,
The recording light is reflected by the recording medium and is reflected by the reflected light.
Deviation between the distance between the objective lens and the recording medium and the desired distance
Position detecting means for detecting the
The objective lens and the recording medium based on the generated deviation.
The feedback control so that the distance of
Control position correction means for correcting the control target position of the control means
The focus control device according to claim 7, further comprising:
光を、記録媒体との距離が一定となるように焦点制御さ
れた対物レンズを通して集光し、前記記録媒体上に情報
を記録 する情報記録媒体原盤作成装置であって、 前記対物レンズの焦点位置が、前記感光材料膜の表面か
ら内部へ向かって厚み方向に、前記感光材料膜の膜厚の
略１／３から略２／３の範囲の値だけ変位した状態に前
記対物レンズの焦点制御を実行する焦点制御手段を設け
たことを特徴とする情報記録媒体原盤作成装置。 10. Recording which is modulated according to the information to be recorded
Focus the light so that the distance from the recording medium is constant.
Information is collected on the recording medium by the focused objective lens.
An information recording medium master disc forming apparatus for recording an information recording medium, wherein the focus position of the objective lens is a surface of the photosensitive material film.
From the inside to the thickness direction, the thickness of the photosensitive material film
Before being displaced by a value in the range of approximately 1/3 to 2/3
Provided with focus control means for executing focus control of the objective lens
An information recording medium master disk producing device characterized by the above.
材料膜の表面から内部へ向かって厚み方向に、前記感光
材料膜の膜厚の略１／２の値だけ変位した状態に前記対
物レンズの焦点制御を実行する請求項１０記載の情報記
録媒体原盤作成装置。 11. The focus position of the objective lens is the photosensitive
In the thickness direction from the surface of the material film to the inside,
The pair is placed in a state in which it is displaced by a value of about ½ of the thickness of the material film.
The information record according to claim 10, wherein focus control of the object lens is executed.
Recording medium master disk creation device.
も波長が長い別の光を用いて前記対物レンズと前記記録
媒体の距離を一定に保つフィードバック制御手段と、前
記記録光が前記記録媒体で反射された反射光を用いて前
記対物レンズと前記記録媒体の距離と所望の距離とのず
れを検出する位置検出手段と、前記位置検出手段により
検出されたずれに基づいて前記対物レンズと前記記録媒
体の距離が所望の距離になるように前記フィードバック
制御手段の制御目標位置を補正する制御位置補正手段か
らなる請求項１０記載の情報記録媒体原盤作成装置。 12. The focus control means uses the recording light.
The objective lens and the recording using another light having a long wavelength.
Feedback control means for keeping the distance of the medium constant,
The recording light is reflected using the reflected light reflected by the recording medium.
The distance between the objective lens and the recording medium and the desired distance
The position detecting means for detecting this and the position detecting means
The objective lens and the recording medium based on the detected shift
The feedback so that the body distance is the desired distance
Control position correction means for correcting the control target position of the control means
The information recording medium master disc forming apparatus according to claim 10, further comprising:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2000344871A JP3506373B2 (en) | 1999-11-16 | 2000-11-13 | Focus control method, information recording medium master creation method, focus control device, and information recording medium master creation device |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP11-324848 | 1999-11-16 | ||
| JP32484899 | 1999-11-16 | ||
| JP2000344871A JP3506373B2 (en) | 1999-11-16 | 2000-11-13 | Focus control method, information recording medium master creation method, focus control device, and information recording medium master creation device |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2003378225A Division JP2004047115A (en) | 1999-11-16 | 2003-11-07 | Method and device for controlling focus, method and device for detecting focal positional deviation, and method and device for manufacturing information recording medium disk original |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2001209951A JP2001209951A (en) | 2001-08-03 |
| JP3506373B2 true JP3506373B2 (en) | 2004-03-15 |
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ID=26571637
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|---|---|---|---|
| JP2000344871A Expired - Fee Related JP3506373B2 (en) | 1999-11-16 | 2000-11-13 | Focus control method, information recording medium master creation method, focus control device, and information recording medium master creation device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3506373B2 (en) |
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