JP2006012416A5 - - Google Patents

Claims (5)

透明基板の厚さが異なる複数種類の光記録媒体毎に、異なる波長の単色光の光ビームを該透明基板を介して入射させ、該光記録媒体の該透明基板に設けられた情報記録面に集光させる正のパワーを有する対物レンズであって、
異なる種類の光記録媒体の情報記録面上に集光させる異なる波長の光ビームが通るレンズ面領域は、光軸から半径方向に複数の区間に区分され、
いずれの種類の該光記録媒体に対しても、対応して集光させる光ビームを、該光ビームの波面収差のうちの最大のＲＭＳ波面収差をＷmax、最小のＲＭＳ波面収差をＷminとして、ＲＭＳ波面収差比が、
１≦Ｗmax／Ｗmin＜１.８
かつＷmax≦０．０３５λ _RMS
を満たす条件で集光させるように、
該区間には夫々、該光ビームの波長λの違いによって発生する色収差と該光記録媒体の透明基板の厚みの違いによって発生する波面収差とを相殺し合う非球面形状が設定されたことを特徴とする対物レンズ。 For each of a plurality of types of optical recording media having different thicknesses of the transparent substrate, a monochromatic light beam having a different wavelength is incident on the information recording surface provided on the transparent substrate of the optical recording medium. An objective lens having a positive power for condensing,
The lens surface area through which the light beams of different wavelengths condensed on the information recording surface of different types of optical recording media pass is divided into a plurality of sections in the radial direction from the optical axis,
For any type of the optical recording medium, a correspondingly condensed light beam is obtained by taking the maximum RMS wavefront aberration among the wavefront aberrations of the light beam as Wmax and the minimum RMS wavefront aberration as Wmin. Wavefront aberration ratio is
1 ≦ Wmax / Wmin <1.8
And Wmax ≦ 0.035λ _RMS
So as to collect light under conditions that satisfy
Each of the sections is provided with an aspheric shape that cancels out chromatic aberration caused by the difference in wavelength λ of the light beam and wavefront aberration caused by the difference in thickness of the transparent substrate of the optical recording medium. Objective lens. 請求項１記載の対物レンズにおいて、
１≦Ｗmax／Ｗmin＜１.６
を満たす条件で集光させるように、非球面形状が設定されたことを特徴とする対物レンズ。 The objective lens according to claim 1, wherein
1 ≦ Wmax / Wmin <1.6
An objective lens characterized in that an aspherical shape is set so as to collect light under conditions satisfying 請求項１記載の対物レンズにおいて、
１≦Ｗmax／Ｗmin＜１.４
を満たす条件で集光させるように、非球面形状が設定されたことを特徴とする対物レンズ。 The objective lens according to claim 1, wherein
1 ≦ Wmax / Wmin <1.4
An objective lens characterized in that an aspherical shape is set so as to collect light under conditions satisfying 請求項１記載の対物レンズにおいて、The objective lens according to claim 1, wherein
前記区間は夫々、各単色光の固有の波長に対応した単一の焦点を有するとともに、該各単色光の固有の波長に対応した焦点は夫々異なる位置に配置されるように構成されたことを特徴とする対物レンズ。Each of the sections has a single focal point corresponding to the unique wavelength of each monochromatic light, and the focal points corresponding to the unique wavelength of each monochromatic light are arranged at different positions. A characteristic objective lens. 複数の異なる波長の単色光の光ビームを発生するレーザと、透明基板の厚さが異なる複数種類の光記録媒体毎に該異なる波長の光ビームが該透明基板を介して入射され、該光記録媒体の該透明基板に設けられた情報記録面に該光ビームを集光させる正のパワーを有する対物レンズと、該対物レンズを介して該光ディスクから反射された該光ビームを検出する光検出器からなる光ピックアップ装置において、The light beam having different wavelengths is incident on each of the plurality of types of optical recording media having different thicknesses of the transparent substrate and the laser that generates the monochromatic light beams having different wavelengths, and the optical recording is performed. An objective lens having a positive power for condensing the light beam on an information recording surface provided on the transparent substrate of the medium, and a photodetector for detecting the light beam reflected from the optical disk via the objective lens In an optical pickup device comprising:
該対物レンズは、異なる種類の光記録媒体の情報記録面上に集光させる異なる波長の光ビームが通るレンズ面領域が、光軸から半径方向に複数の区間に区分され、In the objective lens, a lens surface region through which light beams of different wavelengths to be condensed on information recording surfaces of different types of optical recording media pass is divided into a plurality of sections in the radial direction from the optical axis,
いずれの種類の該光記録媒体に対しても、対応して集光させる光ビームを、該光ビームの波面収差のうちの最大のＲＭＳ波面収差をＷmax、最小のＲＭＳ波面収差をＷminとして、ＲＭＳ波面収差比が、For any type of the optical recording medium, a correspondingly condensed light beam is obtained by taking the maximum RMS wavefront aberration among the wavefront aberrations of the light beam as Wmax and the minimum RMS wavefront aberration as Wmin. Wavefront aberration ratio is
１≦Ｗmax／Ｗmin＜１.８1 ≦ Wmax / Wmin <1.8
かつＷmax≦０．０３５λAnd Wmax ≦ 0.035λ _RMSRMS
を満たす条件で集光させるように、So as to collect light under conditions that satisfy
該区間に夫々、該光ビームの波長λの違いによって発生する色収差と該光記録媒体の透明基板の厚みの違いによって発生する波面収差とを相殺し合う非球面形状が設定されたことを特徴とする光ピックアップ装置。Each of the sections is provided with an aspheric shape that cancels out chromatic aberration caused by a difference in wavelength λ of the light beam and wavefront aberration caused by a difference in thickness of the transparent substrate of the optical recording medium. An optical pickup device.