JP2900648B2 - Super-resolution optical element and optical memory device - Google Patents
Super-resolution optical element and optical memory deviceInfo
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- JP2900648B2 JP2900648B2 JP3197846A JP19784691A JP2900648B2 JP 2900648 B2 JP2900648 B2 JP 2900648B2 JP 3197846 A JP3197846 A JP 3197846A JP 19784691 A JP19784691 A JP 19784691A JP 2900648 B2 JP2900648 B2 JP 2900648B2
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- light
- optical element
- resolution
- resolution optical
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Description
【０００１】[0001]
【産業上の利用分野】本発明は、超解像光学素子及び光
メモリ装置に関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a super-resolution optical element and an optical memory device.
【０００２】[0002]
【従来の技術】光記録媒体の記録密度の向上策として、
現在、種々の方法が検討されているが、実際に記録媒体
上に形成する物理的な記録ピット密度を向上させるため
には、記録媒体上に形成される集光スポット径の縮小が
必要不可欠である。2. Description of the Related Art As a measure for improving the recording density of an optical recording medium,
At present, various methods are being studied, but in order to increase the density of the physical recording pits actually formed on the recording medium, it is indispensable to reduce the diameter of the focused spot formed on the recording medium. is there.
【０００３】一般に、集光スポット径は、レーザ光源波
長に比例し、対物レンズ開口数に反比例する。開口数は
光ヘッドと光磁気記録媒体との位置関係から決定され、
現状以上に大きくすることは難しく、また、レーザ光源
波長についても実用的な構成としては現状以上に小さく
することは困難である。このような集光スポット径の理
論的限界を超える光学的方法として、超解像手法の導入
が検討されている。超解像は、対物レンズの入射ひとみ
上の光ビームの強度及び位相分布を変えることにより、
一様な光ビーム入射時に形成される集光スポット径より
小さな集光スポット径を実現する手段である。In general, the diameter of the focused spot is proportional to the wavelength of the laser light source and inversely proportional to the numerical aperture of the objective lens. The numerical aperture is determined from the positional relationship between the optical head and the magneto-optical recording medium,
It is difficult to make it larger than the current situation, and it is also difficult to make the laser light source wavelength smaller than the current situation as a practical configuration. As an optical method that exceeds the theoretical limit of the focused spot diameter, introduction of a super-resolution method is being studied. Super-resolution is achieved by changing the intensity and phase distribution of the light beam on the entrance pupil of the objective lens.
This is a means for realizing a focused spot diameter smaller than the focused spot diameter formed when a uniform light beam is incident.
【０００４】この超解像の最も簡単な例は、図１０に示
すように中心付近を遮光帯１１で遮光した平行光１２を
対物レンズ１３で集光するものである。中心付近が遮光
される以前の平行光１２の光強度分布は、図中破線で示
すように中央部分ほど高くなっているが、遮光帯１１で
遮光することにより実線で示すように中心付近の光強度
分布は減衰している。この平行光１２を対物レンズ１３
で集光することにより、記録媒体１４表面に集光スポッ
トが形成される。この集光スポットの光分布は、図中破
線で示すように平行光１２を遮光しなかった場合に比較
し、図中実線で示す平行光１２を遮光すると、外側部分
の光波の干渉により、分布が中央に集中し両脇が低くな
る。つまり、平行光１２の中心付近を減衰させると、集
光スポットの径が減少するのである。[0004] The simplest example of this super-resolution is to converge a parallel light 12 whose central part is shielded by a light-shielding band 11 as shown in FIG. The light intensity distribution of the parallel light 12 before the vicinity of the center is shielded is higher toward the center as shown by a broken line in the figure. The intensity distribution is attenuated. This collimated light 12 is passed through an objective lens 13
In this way, a light spot is formed on the surface of the recording medium 14. The light distribution of the condensed spot is smaller than that of the case where the parallel light 12 is not shielded as shown by the broken line in the figure. Is concentrated in the center and both sides are lowered. That is, when the vicinity of the center of the parallel light 12 is attenuated, the diameter of the condensed spot decreases.
【０００５】[0005]
【発明が解決しようとする課題】超解像の原理によれ
ば、理論的限界を越えて集光スポット径を縮小すること
が出来るので、記録密度を一層高めることが可能であ
る。しかし、図１０に示すように遮光帯１１で平行光１
２の中央付近を遮光すると、光量の損失が起こり、光利
用率が低下する問題がある。According to the principle of super-resolution, the diameter of the focused spot can be reduced beyond the theoretical limit, so that the recording density can be further increased. However, as shown in FIG.
When light is shielded in the vicinity of the center of No. 2, there is a problem that a light amount is lost and the light utilization rate is reduced.
【０００６】そこで、図１１に示すように、遮光帯１１
に代えて両菱形プリズム(double rhomb prism)を使用し
た光メモリ装置も提案されている(Proc.Int.Symp.on Op
tical Memory, 1989 Japanese Journal of Applied Phy
sics, Vol.28(1989)Supplement 28-3,pp.197-200)。こ
の光メモリ装置においては、両菱形プリズム２１及びビ
ームスプリッタ２２を、半導体レーザ２３から対物レン
ズ２４までの光学系に挿入したものであり、半導体レー
ザ２３を出射したレーザ光は、両菱形プリズム２１、ビ
ームスプリッタ２２を順に通過した後、対物レンズ２４
により集光されて、記録媒体２５表面に集光スポットを
形成する。更に、信号検出光学系２６、誤差検出光学系
２７が設けられている。Therefore, as shown in FIG.
An optical memory device using a double rhomb prism instead of a double rhomb prism has also been proposed (Proc.Int.Symp.on Op.
tical Memory, 1989 Japanese Journal of Applied Phy
sics, Vol. 28 (1989) Supplement 28-3, pp. 197-200). In this optical memory device, a double rhombic prism 21 and a beam splitter 22 are inserted into an optical system from a semiconductor laser 23 to an objective lens 24. The laser light emitted from the semiconductor laser 23 is After sequentially passing through the splitter 22, the objective lens 24
To form a focused spot on the surface of the recording medium 25. Further, a signal detection optical system 26 and an error detection optical system 27 are provided.
【０００７】ここで、両菱形プリズム２１は、断面が菱
形の板ガラスをＶ字状に一体的に結合し、入射方向に対
して入射面及び出射面が凹状となるように配置したもの
である。従って、この両菱形プリズム２１は、入射した
レーザ光の中央付近の光を外側へ屈折させて、入射した
平行光の中央付近の光を外側へ移動させ、相対的に中心
部の光の分布を低減するものである。この為、両菱形プ
リズム２１を通過したレーザ光は、入射前よりも出射後
の直径が太くなっている。この両菱形プリズム２１を使
用すると、レーザ光は屈折により単に外側に移動するだ
けで、遮光されない為、レーザ光は損失なく利用される
ことになる。Here, the two rhombic prisms 21 are formed by integrally connecting a rhombic plate glass in a V-shaped cross section, and are arranged so that the incident surface and the outgoing surface are concave with respect to the incident direction. Therefore, the two rhombic prisms 21 refract the light near the center of the incident laser light to the outside, move the light near the center of the incident parallel light to the outside, and relatively change the distribution of light at the center. It is to reduce. For this reason, the laser beam that has passed through both rhombic prisms 21 has a larger diameter after emission than before incidence. When the two rhombic prisms 21 are used, the laser light simply moves outward due to refraction and is not shielded, so that the laser light is used without loss.
【０００８】ところが、この両菱形プリズム２１は断面
菱形の板ガラスをＶ字状に結合したものであるため、集
光スポット径の縮小の効果は一方向にしかないという問
題点がある。即ち、両菱形プリズム２１は、光軸に対し
て回転対称形ではないため、屈折により平行光が分散す
る方向は一方向に限られ、その方向については集光スポ
ット径が減少するが、他の方向に対しては屈折しないた
め集光スポット径はそのままであった。この為、両菱形
プリズム２１を使用して得られる集光スポットは、屈折
により分散する方向のみに径の縮小した楕円形となって
いた。従って、集光スポット径の減少による記録密度の
向上についても、一次元的な効果であり、充分な効果を
得ることができなかった。However, since both rhombic prisms 21 are formed by connecting glass plates having a rhombic cross section in a V-shape, there is a problem that the effect of reducing the diameter of the condensed spot is only in one direction. That is, since the two rhombic prisms 21 are not rotationally symmetric with respect to the optical axis, the direction in which parallel light is dispersed due to refraction is limited to one direction, and the condensing spot diameter decreases in that direction. Since the beam was not refracted in the direction, the diameter of the focused spot remained unchanged. For this reason, the condensed spot obtained by using both rhombic prisms 21 has an elliptical shape whose diameter is reduced only in the direction of dispersion due to refraction. Therefore, the improvement of the recording density due to the decrease in the diameter of the condensing spot is also a one-dimensional effect, and a sufficient effect cannot be obtained.
【０００９】本発明は、上記従来技術に鑑みて成された
ものであり、光エネルギーを有効に活用し、全ての方向
に対して超解像の効果の得られる超解像光学素子及び光
メモリ装置を提供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and a super-resolution optical element and an optical memory device capable of effectively utilizing light energy and obtaining a super-resolution effect in all directions. The purpose is to provide.
【００１０】斯かる目的を達成する本発明の超解像光学
素子に係る構成は入射面及び出射面を入射方向に対して
凹状とし、入射光の中央付近の光を外周側に移動させる
超解像光学素子において、前記入射面及び出射面を光軸
に対して回転対称な連続した滑らかな曲線形状を有する
非球面形状とし、入射面の軸上半径の絶対値を出射面の
軸上半径の絶対値よりも小さく又は等しくし、かつ、光
軸上の入射光は直進して出射面の光軸上から出射される
ことを特徴とする。ここで、上記超解像光学素子の入射
面及び出射面の形状は、非球面形状とした場合、外周側
へ向かうに従い徐々に曲率半径を増大させ、最外周部分
における曲率半径を無限大とすることにより、最外周部
分において光を直進させることが望ましい。また、上記
目的を達成する本発明に係る光メモリの構成は、上記超
解像光学素子をレーザ発振器から対物レンズまでの光学
系中に挿入し、前記レーザ発振器より出射したレーザ光
を前記超解像光学素子を通過させて中央付近の光を外周
側へ移動させたレーザ光とし、このレーザ光を対物レン
ズで集光して記録媒体表面に集光スポットを形成するこ
とを特徴とする。According to the structure of the super-resolution optical element of the present invention which achieves the above object, the entrance surface and the exit surface are concave with respect to the incident direction, and the light near the center of the incident light is moved to the outer peripheral side.
In the super-resolution optical element, the entrance surface and the exit surface are optical axes.
Has a continuous smooth curve shape that is rotationally symmetric with respect to
The aspheric shape, and the absolute value of the on-axis radius of the entrance surface
Smaller or equal to the absolute value of the on-axis radius, and
The incident light on the axis goes straight and is emitted from the optical axis on the emission surface . Here, when the shape of the entrance surface and the exit surface of the super-resolution optical element is an aspherical shape, the radius of curvature is gradually increased toward the outer peripheral side, and the radius of curvature at the outermost peripheral portion is set to infinity. Accordingly, it is desirable that the light travel straight in the outermost peripheral portion. Further, in the configuration of the optical memory according to the present invention for achieving the above object, the super-resolution optical element is inserted into an optical system from a laser oscillator to an objective lens, and the laser light emitted from the laser oscillator is subjected to the super-resolution. It is characterized in that the light near the center is passed through the optical element and turned into laser light which is moved to the outer peripheral side, and this laser light is condensed by an objective lens to form a condensed spot on the surface of the recording medium.
【００１１】[0011]
【作用】平行光を、超解像光学素子に通過させると、そ
の平行光の中心部の光は直進するが、その中央付近の光
は外周側へ移動する。その後、この平行光を、対物レン
ズで集光すると記録媒体表面には縮小した集光スポット
が形成される。[Action] The parallel light, when passing through the super-resolution optical element, the light of the central portion of the parallel light of that <br/> is straight, light near the center is moved to the outer peripheral side. Thereafter, when the parallel light is condensed by the objective lens, a reduced condensed spot is formed on the surface of the recording medium.
【００１２】また、超解像光学素子の入射面及び出射面
は回転対称な円錐形又は非球面形状である為、超解像の
効果は二次元的に生じ、従って、集光スポットはほぼ円
形となる。更に、超解像光学素子の入射面及び出射面を
非球面形状とした場合には、外周側へ向かうに従い徐々
に曲率半径を増大させ、最外周部分における曲率半径を
無限大とすると、最外周部分において光を直進すること
になる。Since the entrance surface and the exit surface of the super-resolution optical element have a rotationally symmetrical conical or aspherical shape, the effect of super-resolution occurs two-dimensionally. Becomes Further, when the entrance surface and the exit surface of the super-resolution optical element have an aspherical shape, the radius of curvature is gradually increased toward the outer peripheral side, and the radius of curvature at the outermost peripheral portion is made infinite. Light will go straight in the part.
【００１３】[0013]
【実施例】以下、本発明について、図面を示す実施例を
参照して詳細に説明する。図１〜図４に、本発明の第
一、第二、第三、第四の実施例に係る超解像光学素子
１，２，３，４を示す。これらの超解像光学素子は、入
射面及び出射面を光軸に対し回転対称形、且つ、入射方
向に対して凹状となる非球面形状としたものである。こ
こで、非球面形状を決定する一般的な式としては、下式
が知られている。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to embodiments shown in the drawings. 1 to 4 show super-resolution optical elements 1, 2, 3, and 4 according to first, second, third, and fourth embodiments of the present invention. In these super-resolution optical elements, the entrance surface and the exit surface have a rotationally symmetric shape with respect to the optical axis and an aspherical shape which is concave with respect to the incident direction. Here, the following equation is known as a general equation for determining the aspherical shape.
【数１】 ここで、ｚは光軸中心から距離ｈにおける入射面又は出
射面の凹部の深さ、ｈは光軸からの距離、ｃは光軸中心
における曲率半径（軸上半径）の逆数、ｋは離芯率(con
ic coefficient) 、Ａ，Ｂ，Ｃ，Ｄは四次係数、六次係
数、八次係数、十次係数である。離芯率ｋを調整するこ
とにより、楕円形、放物線、双曲線となる。(Equation 1) Here, z is the depth of the concave portion of the entrance surface or the exit surface at a distance h from the optical axis center, h is the distance from the optical axis, c is the reciprocal of the radius of curvature (axial radius) at the optical axis center, and k is the distance. Core ratio (con
ic coefficient), A, B, C, and D are a fourth-order coefficient, a sixth-order coefficient, an eighth-order coefficient, and a tenth-order coefficient. By adjusting the eccentricity k, an ellipse, a parabola, and a hyperbola are obtained.
【００１４】図１に示す第一の実施例にかかる超解像光
学素子１においては、入射面１ａの軸上半径-2.13945mm
とし、出射面１ｂの軸上半径を-2.46406mmとした。軸上
半径の負の符号は、入射方向側であることを示すもので
ある。また、光軸中心における厚さは1.0mmとした。更
に、入射面１ａの離芯率は-4.185151 、四次係数は0.26
993347×10-1、六次係数0.19058752×10-2、八次係数は
-0.75519682 ×10-3、十次係数は0.33273314×10-4とし
た。出射面１ｂの離芯率は-2.890459 、四次係数は0.23
012729×10-1、六次係数0.98024068×10-3、八次係数は
0.68755311×10-3、十次係数は-0.19333458 ×10-3とし
た。In the super-resolution optical element 1 according to the first embodiment shown in FIG. 1, the axial radius of the entrance surface 1a is -2.113945 mm.
And the on-axis radius of the exit surface 1b was -2.446406 mm. A negative sign of the on-axis radius indicates that it is on the incident side. The thickness at the center of the optical axis was 1.0 mm. Further, the eccentricity of the incident surface 1a is -4.185151, and the fourth order coefficient is 0.26.
993347 × 10 -1 , sixth order coefficient 0.19058752 × 10 -2 , eighth order coefficient
-0.75519682 × 10 -3 and the tenth coefficient were 0.33273314 × 10 -4 . The eccentricity of the exit surface 1b is -2.890459, and the fourth order coefficient is 0.23
012729 × 10 -1 , sixth order coefficient 0.98024068 × 10 -3 , eighth order coefficient
0.68755311 × 10 −3 , and the tenth coefficient was −0.19333458 × 10 −3 .
【００１５】図２に示す第二の実施例にかかる超解像光
学素子２においては、入射面２ａの軸上半径-1.04867mm
とし、出射面２ｂの軸上半径を-2.78517mmとした。ま
た、光軸中心における厚さは4.8733229mmとした。更
に、入射面２ａの離芯率は-12.554973、四次係数は0.12
506795×10-1、六次係数0.55731091×10-2、八次係数は
-0.20267974 ×10-2、十次係数は0.21601358×10-3とし
た。出射面２ｂの離芯率は-0.841947 、四次係数は0.27
092645×10-1、六次係数0.42985658×10-2、八次係数は
-0.34022827 ×10-2、十次係数は0.78906940×10-3とし
た。In the super-resolution optical element 2 according to the second embodiment shown in FIG. 2, the axial radius of the entrance surface 2a is -1.04867 mm.
The axial radius of the exit surface 2b was -2.778517 mm. The thickness at the center of the optical axis was 4.8733229 mm. Further, the eccentricity of the incident surface 2a is -12.554973, and the fourth order coefficient is 0.12.
506795 × 10 -1 , 6th order coefficient 0.55731091 × 10 -2 , 8th order coefficient
-0.20267974 × 10 -2 , and the tenth coefficient was 0.21601358 × 10 -3 . The eccentricity of the exit surface 2b is -0.841947, and the fourth order coefficient is 0.27
092645 × 10 -1 , 6th order coefficient 0.42985658 × 10 -2 , 8th order coefficient
-0.34022827 × 10 -2 and the tenth coefficient was 0.78906940 × 10 -3 .
【００１６】図３に示す第三の実施例にかかる超解像光
学素子３においては、入射面３ａの軸上半径-0.94317mm
とし、出射面３ｂの軸上半径を-1.30241mmとした。ま
た、光軸中心における厚さは1.1013583mmとした。更
に、入射面３ａの離芯率は-3.056169 、四次係数は0.21
792927×10-1、六次係数0.76161776×10-2、八次係数は
-0.14180368 ×10-2、十次係数は0.84229251×10-4とし
た。出射面３ｂの離芯率は-1.882294 、四次係数は0.36
631075×10-1、六次係数0.18080063×10-2、八次係数は
0.45144929×10-3、十次係数は0.18918591×10-3とし
た。In the super-resolution optical element 3 according to the third embodiment shown in FIG. 3, the on-axis radius of the entrance surface 3a is -0.994317 mm.
And the on-axis radius of the exit surface 3b was -1.30241 mm. The thickness at the center of the optical axis was 1.1133583 mm. Further, the eccentricity of the incident surface 3a is -3.056169, and the fourth order coefficient is 0.21.
792927 × 10 -1 , sixth order coefficient 0.76161776 × 10 -2 , eighth order coefficient
-0.14180368 × 10 -2 , and the tenth coefficient was 0.84229251 × 10 -4 . The eccentricity of the exit surface 3b is -1.882294, and the fourth order coefficient is 0.36
631075 × 10 −1 , 6th order coefficient 0.18080063 × 10 −2 , 8th order coefficient
0.45144929 × 10 −3 , and the tenth coefficient was 0.18918591 × 10 −3 .
【００１７】図４に示す第四の実施例にかかる超解像光
学素子４においては、入射面４ａの軸上半径-1.221441m
とし、出射面４ｂの軸上半径を-1.41540mmとした。ま
た、光軸中心における厚さは1.0mmとした。更に、入射
面４ａの離芯率は-2.446259、四次係数は0.28997414×1
0-1、六次係数0.77932203×10-2、八次係数は-0.199107
51 ×10-2、十次係数は0.16195741×10-3とした。出射
面４ｂの離芯率は-1.801742 、四次係数は0.33397917×
10-1、六次係数0.28564638×10-2、八次係数は0.184832
91×10-3、十次係数は-0.56183950 ×10-4とした。In the super-resolution optical element 4 according to the fourth embodiment shown in FIG. 4, the on-axis radius of the entrance surface 4a is -1.2221441 m.
And the on-axis radius of the exit surface 4b was -1.415540 mm. The thickness at the center of the optical axis was 1.0 mm. Further, the eccentricity of the incident surface 4a is -2.444659, and the fourth order coefficient is 0.28997414 × 1
0 -1 , 6th order coefficient 0.77932203 × 10 -2 , 8th order coefficient is -0.199107
51 × 10 -2 and the tenth coefficient were 0.16195741 × 10 -3 . The eccentricity of the emission surface 4b is -1.801742, and the fourth order coefficient is 0.33397917 ×
10 -1 , sixth-order coefficient 0.28564638 × 10 -2 , eighth-order coefficient 0.184832
The coefficient was set to 91 × 10 −3 and the tenth coefficient was −0.56183950 × 10 −4 .
【００１８】上記第一〜第四の実施例においては、出射
面１ｂ〜４ｂを入射面１ａ〜４ａに比べて深い凹状と
し、外周側へ向かうに従い徐々に曲率半径を増大させ、
最外周部分における曲率半径を無限大とするため、入射
面１ａ〜４ａの軸上半径よりも出射面１ｂ〜４ｂの軸上
半径を大きくし、入射面１ａ〜４ａの離芯率を負とし、
また、八次係数を負とした。In the first to fourth embodiments, the exit surfaces 1b to 4b are formed in a concave shape deeper than the entrance surfaces 1a to 4a, and the radius of curvature is gradually increased toward the outer peripheral side.
In order to make the radius of curvature in the outermost peripheral portion infinite, the on-axis radius of the exit surfaces 1b to 4b is made larger than the on-axis radius of the entrance surfaces 1a to 4a, and the eccentricity of the entrance surfaces 1a to 4a is made negative.
In addition, the eighth order coefficient was made negative.
【００１９】上記実施例に係る超解像光学素子１〜４に
平行光を入射すると、入射面１ａ〜４ａ及び出射面１ｂ
〜４ｂの形状に基づいて、外周及び中心では、光がほぼ
直進するが、中心付近では光が外周方向へ移動する。こ
こで、入射面における中心付近の光としては、図５に示
すように平行光の半径を１としたときの光軸中心から0.
5離れた位置の光であるとする。この中心付近の光が出
射面において出射する位置を光軸中心から測定すると、
第一の実施例では、ｘ＝0.55となり、第二の実施例では
ｘ＝0.75となり、第三の実施例ではｘ＝0.60となり、ま
た、第四の実施例ではｘ＝0.55となった。When parallel light enters the super-resolution optical elements 1 to 4 according to the above embodiment, the incident surfaces 1a to 4a and the exit surface 1b
4b, the light travels substantially straight at the outer periphery and the center, but moves toward the outer periphery near the center. Here, as the light near the center on the incident surface, as shown in FIG.
It is assumed that the light is at a distance of 5 places. When the position where the light near this center is emitted on the emission surface is measured from the center of the optical axis,
In the first embodiment, x = 0.55, in the second embodiment, x = 0.75, in the third embodiment, x = 0.60, and in the fourth embodiment, x = 0.55.
【００２０】このような光の移動の効果は、超解像光学
素子１〜４の入射面１ａ〜４ａ、出射面１ｂ〜４ｂは光
軸に対して回転対称であるため、特定の方向にのみに起
こるのではなく、全ての方向に対して起こる。従って、
超解像光学素子１〜４を通過した平行光を対物レンズ５
で集光すると、記録媒体６上の集光スポットは、超解像
光学素子１〜４を使用しない場合に比較し、小径となる
と共にその形状は楕円形ではなく円形となる。The effect of such light movement is that the entrance surfaces 1a to 4a and the exit surfaces 1b to 4b of the super-resolution optical elements 1 to 4 are rotationally symmetric with respect to the optical axis, so that they can be moved only in a specific direction. Rather than happening in all directions. Therefore,
The parallel light passing through the super-resolution optical elements 1 to 4 is
When the light is condensed, the condensed spot on the recording medium 6 has a smaller diameter and a circular shape instead of an elliptical shape as compared with the case where the super-resolution optical elements 1 to 4 are not used.
【００２１】例えば、超解像光学素子を使用した場合と
使用しない場合とを比較して図６に示す。同図に示すよ
うに超解像光学素子を使用しない場合、つまり、ｘ＝0.
5のときの集光スポット径が1.25μmでであるとすると、
本実施例の超解像光学素子を使用してｘ＝0.6,0.7,0.8
とすると集光スポット径は1.15μm,1.10μm,1.05μm と
減少することが判る。本発明では、集光スポットの形状
が楕円形ではなく円形である為、集光スポット径の減少
の効果は、その二乗の効果をもって、記録密度に影響す
る。例えば、集光スポット径が10％減少すると、記録密
度は単純に考えて１／（１−0.1)2 ＝1.23倍に向上し、
また、集光スポット径が20％減少すると、記録密度は単
純に考えて１／（１−0.2)2＝1.56倍に向上する。For example, FIG. 6 shows a comparison between a case where a super-resolution optical element is used and a case where it is not used. As shown in the figure, when no super-resolution optical element is used, that is, x = 0.
Assuming that the focused spot diameter at 5 is 1.25 μm,
Using the super-resolution optical element of this embodiment, x = 0.6, 0.7, 0.8
Then, it can be seen that the diameter of the focused spot decreases to 1.15 μm, 1.10 μm, and 1.05 μm. In the present invention, since the shape of the condensed spot is not elliptical but circular, the effect of reducing the diameter of the condensed spot affects the recording density with the square effect. For example, if the condensing spot diameter is reduced by 10%, the recording density is simply increased to 1 / (1−0.1) 2 = 1.23 times,
Further, when the diameter of the focused spot is reduced by 20%, the recording density is improved to 1 / (1−0.2) 2 = 1.56 times simply.
【００２２】尚、上記超解像光学素子１〜４では、各光
線の角度は、入射前と出射後では変化せず、平行光が入
射すると平行光を出射する。基本的には、本実施例の超
解像光学素子は無焦点光学系（アフォーカル光学系）で
ある。但し、コマ収差の発生を防止するため、平行光に
対して上記超解像光学素子１〜４は正確に垂直に光学素
子を入れる必要がある。In the super-resolution optical elements 1 to 4, the angle of each light beam does not change before and after the light is emitted, and the parallel light is emitted when the parallel light enters. Basically, the super-resolution optical element of this embodiment is an afocal optical system (afocal optical system). However, in order to prevent the occurrence of coma, it is necessary that the super-resolution optical elements 1 to 4 enter the optical elements exactly perpendicular to the parallel light.
【００２３】ここで、超解像光学素子１〜４の入射面１
ａ〜４ａ、出射面１ｂ〜４ｂは、外周側へ向かうに従い
徐々に曲率半径が大きくなり、最外周部分では曲率半径
を無限大としている為、つまり、入射光に対して垂直面
とした為、入射した平行光と出射する平行光の直径が同
じとなる。この為、対物レンズの直径としては、超解像
光学素子を使用する場合でも、特に大径とする必要がな
く、超解像光学素子を使用しない場合と同じの直径でよ
く、また、超解像光学素子の入射前後において、単位面
積当たりの光エネルギーの平均が変化せず、集光スポッ
トでのエネルギー密度が良好に保たれることになる。Here, the incident surface 1 of the super-resolution optical elements 1 to 4
a to 4a, the emission surfaces 1b to 4b gradually increase in radius of curvature toward the outer peripheral side, and the radius of curvature is set to infinity in the outermost peripheral portion, that is, because the outer surface is perpendicular to the incident light, The diameters of the incident parallel light and the outgoing parallel light are the same. For this reason, the diameter of the objective lens does not need to be particularly large even when using a super-resolution optical element, and may be the same diameter as when the super-resolution optical element is not used. Before and after incidence on the image optical element, the average of the light energy per unit area does not change, and the energy density at the condensed spot is kept good.
【００２４】尚、上記実施例では、超解像光学素子に入
射した平行光と出射する平行光との直径が等しいが、必
ずしもこれに限られない。例えば、図７に示す第五の実
施例の超解像光学素子７においては、入射面７ａの最外
周部分に入射した光を出射面７ｂにおいて外側に移動し
て出射するようにしている。In the above embodiment, the diameter of the parallel light incident on the super-resolution optical element is equal to the diameter of the parallel light emitted therefrom, but the present invention is not limited to this. For example, in the super-resolution optical element 7 according to the fifth embodiment shown in FIG. 7, light incident on the outermost peripheral portion of the incident surface 7a is moved outward on the emission surface 7b and emitted.
【００２５】次に、上記超解像光学素子を使用する光メ
モリ装置の第一、第二の実施例について、図８、図９に
示す。図８に示す実施例においては信号検出光学系と、
光源である半導体レーザとを分離したものであるが、図
９に示す実施例においては、それらを一体化したもので
ある。Next, FIGS. 8 and 9 show first and second embodiments of the optical memory device using the above-mentioned super-resolution optical element. In the embodiment shown in FIG. 8, a signal detection optical system,
Although the semiconductor laser as a light source is separated, in the embodiment shown in FIG. 9, they are integrated.
【００２６】即ち、図８に示す実施例では、記録媒体３
１の半径方向に移動自在に配設された可動ヘッド３２に
対物レンズ３３、全反射プリズム３４が搭載されると共
にこの可動ヘッド３２と半導体レーザ３８との間に信号
検出光学系３５が設置されている。この信号検出光学系
３５と半導体レーザ３８との間にはコリメートレンズ３
７及び本実施例の超解像光学素子３６が設置されてお
り、半導体レーザ３８を出射したレーザ光が、コリメー
トレンズ３７、超解像光学素子３６、信号検出光学系３
５を通過するようになっている。信号検出光学系３５を
通過したレーザ光は、可動ヘッド３２に到達し、全反射
プリズム３４、対物レンズ３３を介して記録媒体３１表
面に集光スポットを形成する。この集光スポットは、レ
ーザ光が超解像光学素子３６を通過しているため、超解
像光学素子３６を使用しない場合に比較し径が減少する
ことになる。That is, in the embodiment shown in FIG.
An objective lens 33 and a total reflection prism 34 are mounted on a movable head 32 movably arranged in a radial direction of the first optical system, and a signal detection optical system 35 is provided between the movable head 32 and the semiconductor laser 38. I have. A collimating lens 3 is provided between the signal detection optical system 35 and the semiconductor laser 38.
7 and the super-resolution optical element 36 of the present embodiment are installed, and the laser light emitted from the semiconductor laser 38 is transmitted to the collimator lens 37, the super-resolution optical element 36, and the signal detection optical system 3.
5 through. The laser light that has passed through the signal detection optical system 35 reaches the movable head 32 and forms a focused spot on the surface of the recording medium 31 via the total reflection prism 34 and the objective lens 33. Since the laser light passes through the super-resolution optical element 36, the diameter of this condensed spot is smaller than when the super-resolution optical element 36 is not used.
【００２７】記録媒体３１表面から反射した光は、可動
ヘッド３２の対物レンズ３３、全反射プリズム３４を経
て信号検出光学系３５で分岐され、図示しないフォトダ
イオードで検出されることになる。一方、図９に示す実
施例では、半導体レーザとフォトダイオードとを一体化
したユニット３９を使用するものである。即ち、本実施
例では、光源となる半導体レーザ３８と信号検出光学系
３５となるフォトダイオードと一体化したものであり、
更に回折素子４０を本実施例の超解像光学素子３６とコ
リメートレンズ３７との間に設けたものである。The light reflected from the surface of the recording medium 31 passes through the objective lens 33 of the movable head 32 and the total reflection prism 34, is branched by the signal detection optical system 35, and is detected by a photodiode (not shown). On the other hand, in the embodiment shown in FIG. 9, a unit 39 in which a semiconductor laser and a photodiode are integrated is used. That is, in this embodiment, the semiconductor laser 38 serving as a light source and the photodiode serving as a signal detection optical system 35 are integrated with each other.
Further, a diffraction element 40 is provided between the super-resolution optical element 36 of this embodiment and the collimating lens 37.
【００２８】本実施例の超解像光学素子３６の挿入され
る位置は、特に限定はなく、半導体レーザ３８と対物レ
ンズ３３の間の光学系であれば何処でも良い。尚、上記
実施例では超解像光学素子の入射面、出射面は非球面形
状となっていたが、非球面形状に代えて円錐形状として
も同様な効果を発揮する。但し、超解像光学素子の入射
面、出射面を円錐形状とすると、出射する光の光分布
は、非球面形状の場合と多少異なるものと予想される。
その場合には、その光分布を修正するための光学素子を
併用するようにすると良い。The position where the super-resolution optical element 36 of the present embodiment is inserted is not particularly limited, and may be any optical system between the semiconductor laser 38 and the objective lens 33. In the above embodiment, the entrance surface and the exit surface of the super-resolution optical element are aspherical. However, the same effect can be obtained by using a conical shape instead of the aspherical shape. However, when the entrance surface and the exit surface of the super-resolution optical element have a conical shape, the light distribution of the emitted light is expected to be slightly different from the case of the aspherical shape.
In that case, it is preferable to use an optical element for correcting the light distribution.
【００２９】[0029]
【発明の効果】以上、実施例に基づいて具体的に説明し
たように、本発明は、超解像光学素子の入射面、出射面
の形状を光軸に対して回転対称とするので、超解像の効
果を二次元的に拡張することができる。従って、この超
解像光学素子を光メモリ装置に使用すると、記録密度を
格段に向上することが可能となる。尚、本発明の光メモ
リ装置は、記録再生可能なものに限らず再生専用のもの
でも適用可能である。尚、本発明の光メモリ装置は、記
録再生可能なものに限らず、再生専用のものでも適用可
能である。As described above in detail with reference to the embodiments, according to the present invention, the shapes of the entrance surface and the exit surface of the super-resolution optical element are rotationally symmetric with respect to the optical axis. The effect of resolution can be extended two-dimensionally. Therefore, when this super-resolution optical element is used in an optical memory device, the recording density can be remarkably improved. The optical memory device of the present invention is not limited to a device capable of recording and reproducing, but may be a device dedicated to reproducing. Note that the optical memory device of the present invention is not limited to a device capable of recording and reproducing, but may be a device dedicated to reproducing.
【図１】本発明の超解像光学素子の第一の実施例を示す
断面図である。FIG. 1 is a sectional view showing a first embodiment of a super-resolution optical element according to the present invention.
【図２】本発明の超解像光学素子の第二の実施例を示す
断面図である。FIG. 2 is a sectional view showing a second embodiment of the super-resolution optical element of the present invention.
【図３】本発明の超解像光学素子の第三の実施例を示す
断面図である。FIG. 3 is a sectional view showing a third embodiment of the super-resolution optical element according to the present invention.
【図４】本発明の超解像光学素子の第四の実施例を示す
断面図である。FIG. 4 is a sectional view showing a fourth embodiment of the super-resolution optical element of the present invention.
【図５】超解像光学素子に入射する平行光と出射する平
行光を示す説明図である。FIG. 5 is an explanatory diagram showing parallel light entering and exiting a super-resolution optical element.
【図６】光軸中心からの距離と集光スポット径との関係
を示すグラフである。FIG. 6 is a graph showing the relationship between the distance from the center of the optical axis and the diameter of a focused spot.
【図７】本発明の超解像光学素子の第五の実施例を示す
断面図である。FIG. 7 is a sectional view showing a fifth embodiment of the super-resolution optical element of the present invention.
【図８】本発明の光メモリ装置の第一の実施例を示す構
成図である。FIG. 8 is a configuration diagram showing a first embodiment of the optical memory device of the present invention.
【図９】本発明の光メモリ装置の第二の実施例を示す構
成図である。FIG. 9 is a configuration diagram showing a second embodiment of the optical memory device of the present invention.
【図１０】超解像の原理を示す説明図である。FIG. 10 is an explanatory diagram showing the principle of super-resolution.
【図１１】従来の超解像を利用した光メモリ装置の構成
図である。FIG. 11 is a configuration diagram of a conventional optical memory device using super-resolution.
１，２，３，４，７ 超解像光学素子 １ａ，２ａ，３ａ，４ａ，７ａ 入射面 １ｂ，２ｂ，３ｂ，４ｂ，７ｂ 出射面 ５ 対物レンズ ６ 記録媒体 ３１ 記録媒体 ３２ 可動ヘッド ３３ 対物レンズ ３４ 全反射プリズム ３５ 信号検出光学系 ３６ 超解像光学素子 ３７ コリメートレンズ ３８ 半導体レーザ ３９ 半導体レーザ及びフォトダイオード一体化ユニッ
ト ４０ 回折素子1, 2, 3, 4, 7 Super-resolution optical element 1a, 2a, 3a, 4a, 7a Incident surface 1b, 2b, 3b, 4b, 7b Exit surface 5 Objective lens 6 Recording medium 31 Recording medium 32 Movable head 33 Object Lens 34 Total reflection prism 35 Signal detection optical system 36 Super-resolution optical element 37 Collimating lens 38 Semiconductor laser 39 Semiconductor laser and photodiode integrated unit 40 Diffraction element
Claims (3)
状とし、入射光の中央付近の光を外周側に移動させる超
解像光学素子において、前記入射面及び出射面を光軸に
対して回転対称な連続した滑らかな曲線形状を有する非
球面形状とし、入射面の軸上半径の絶対値を出射面の軸
上半径の絶対値よりも小さく又は等しくし、かつ、光軸
上の入射光は直進して出射面の光軸上から出射されるこ
とを特徴とする超解像光学素子。1. An ultra-light emitting device, wherein an incident surface and an outgoing surface are concave with respect to an incident direction, and light near a center of incident light is moved to an outer peripheral side.
In the resolution optical element, the entrance surface and the exit surface are set to the optical axis.
Non-continuous smooth curve shape that is rotationally symmetric to
Spherical shape and the absolute value of the on-axis radius of the entrance surface
Smaller or equal to the absolute value of the upper radius, and the optical axis
A super-resolution optical element characterized in that the upper incident light travels straight and exits from the optical axis of the exit surface .
面の非球面形状は、外周側へ向かうに従い徐々に曲率半
径を増大させ、最外周部分における曲率半径を無限大と
することにより、最外周部分において光を直進させるこ
とを特徴とする超解像光学素子。2. The aspherical surface of the entrance surface and the exit surface according to claim 1, wherein the radius of curvature is gradually increased toward the outer peripheral side, and the radius of curvature at the outermost peripheral portion is made infinite, whereby A super-resolution optical element, wherein light travels straight in an outer peripheral portion.
子をレーザ発振器から対物レンズまでの光学系中に挿入
し、前記レーザ発振器より出射したレーザ光を前記超解
像光学素子を通過させて中央付近の光を外周側へ移動さ
せたレーザ光とし、このレーザ光を対物レンズで集光し
て記録媒体表面に集光スポットを形成することを特徴と
する光メモリ装置。3. The super-resolution optical element according to claim 1 or 2 is inserted into an optical system from a laser oscillator to an objective lens, and laser light emitted from the laser oscillator passes through the super-resolution optical element. An optical memory device characterized in that the light in the vicinity of the center is converted into laser light that is moved to the outer peripheral side, and the laser light is condensed by an objective lens to form a converged spot on the surface of the recording medium.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3197846A JP2900648B2 (en) | 1991-08-07 | 1991-08-07 | Super-resolution optical element and optical memory device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3197846A JP2900648B2 (en) | 1991-08-07 | 1991-08-07 | Super-resolution optical element and optical memory device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH06223401A JPH06223401A (en) | 1994-08-12 |
| JP2900648B2 true JP2900648B2 (en) | 1999-06-02 |
Family
ID=16381315
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3197846A Expired - Fee Related JP2900648B2 (en) | 1991-08-07 | 1991-08-07 | Super-resolution optical element and optical memory device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2900648B2 (en) |
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| US6356395B1 (en) | 1998-09-14 | 2002-03-12 | Fujitsu Limited | Light intensity distribution converting device and optical data storage apparatus |
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|---|---|---|---|---|
| US6014360A (en) * | 1996-03-18 | 2000-01-11 | Seiko Epson Corporation | Optical recording medium having a track pitch less than the wavelength of a laser beam |
| JP2001236673A (en) * | 2000-02-17 | 2001-08-31 | Minolta Co Ltd | Optical head and optical recording and reproducing device |
| AU2002234913A1 (en) | 2002-02-27 | 2003-09-09 | Fujitsu Limited | Optical recording medium, its recording/reproducing apparatus, its storage apparatus, and its recording/reproducing method |
| CN103543516B (en) * | 2013-09-26 | 2016-03-30 | 宁波舜宇红外技术有限公司 | A kind of LONG WAVE INFRARED wide-angle lens |
| CN109564338B (en) * | 2018-11-08 | 2020-12-11 | 深圳市汇顶科技股份有限公司 | Lens group, fingerprint identification device and electronic equipment |
-
1991
- 1991-08-07 JP JP3197846A patent/JP2900648B2/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6201229B1 (en) | 1998-03-09 | 2001-03-13 | Fujitsu Limited | Light intensity converter |
| US6356395B1 (en) | 1998-09-14 | 2002-03-12 | Fujitsu Limited | Light intensity distribution converting device and optical data storage apparatus |
| US6469838B2 (en) | 1998-09-14 | 2002-10-22 | Fujitsu Limited | Illumination device having light intensity distribution converting elements |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06223401A (en) | 1994-08-12 |
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