JPH0533466B2 - - Google Patents
Info
- Publication number
- JPH0533466B2 JPH0533466B2 JP58062989A JP6298983A JPH0533466B2 JP H0533466 B2 JPH0533466 B2 JP H0533466B2 JP 58062989 A JP58062989 A JP 58062989A JP 6298983 A JP6298983 A JP 6298983A JP H0533466 B2 JPH0533466 B2 JP H0533466B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- incident
- output
- light beam
- optical axis
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000003287 optical effect Effects 0.000 claims description 63
- 230000010287 polarization Effects 0.000 claims description 12
- 239000004065 semiconductor Substances 0.000 description 21
- 238000007493 shaping process Methods 0.000 description 6
- 238000001514 detection method Methods 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- NCGICGYLBXGBGN-UHFFFAOYSA-N 3-morpholin-4-yl-1-oxa-3-azonia-2-azanidacyclopent-3-en-5-imine;hydrochloride Chemical compound Cl.[N-]1OC(=N)C=[N+]1N1CCOCC1 NCGICGYLBXGBGN-UHFFFAOYSA-N 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- CPBQJMYROZQQJC-UHFFFAOYSA-N helium neon Chemical compound [He].[Ne] CPBQJMYROZQQJC-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1398—Means for shaping the cross-section of the beam, e.g. into circular or elliptical cross-section
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
- G11B7/135—Means for guiding the beam from the source to the record carrier or from the record carrier to the detector
- G11B7/1356—Double or multiple prisms, i.e. having two or more prisms in cooperation
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Head (AREA)
Description
【発明の詳細な説明】
〔発明の利用分野〕
本発明は、光学的情報記録、読取装置における
光学ヘツドにおいて用いる偏光ビームスプリツタ
に関するものであり、更に詳しくは、光源として
半導体レーザなどを用いた場合に、発生する光ビ
ームの光軸に対し直交する面内における光量分布
が楕円形状になる傾向にあるので、これを真円形
に整形する光学手段を兼ねうるようにした前記偏
光ビームスプリツタに関するものである。[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a polarizing beam splitter used in an optical head in an optical information recording and reading device. In this case, the light intensity distribution in a plane perpendicular to the optical axis of the generated light beam tends to be elliptical, so the polarizing beam splitter can also serve as an optical means for shaping the light beam into a perfect circle. It is something.
光情報担体（以下デイスク、と略す）に光学的
に情報を記録または再生するための光学ヘツドに
おいては、光源として従来よりヘリウム・ネオン
レーザ、アルゴンレーザ等のガスレーザが用いら
れてきたが、近年小型でかつ直接変調の可能な半
導体レーザが用いられるようになつてきた。周知
のように、一般に半導体レーザは、その光出力が
15〜25ｍＷと従来のガスレーザに比較して小さ
く、さらにその光ビームは遠視野像が楕円になる
という非等方的なもの（換言すると、半導体レー
ザからの発光ビームの断面パターンが真円形でな
く楕円形になるということ）が通例である。
Gas lasers such as helium-neon lasers and argon lasers have traditionally been used as light sources in optical heads for optically recording or reproducing information on optical information carriers (hereinafter referred to as disks), but in recent years small-sized lasers have been used. Semiconductor lasers that can be directly modulated have come into use. As is well known, semiconductor lasers generally have a light output of
At 15 to 25 mW, it is small compared to conventional gas lasers, and its light beam is anisotropic, with a far-field pattern that is elliptical (in other words, the cross-sectional pattern of the emitted beam from the semiconductor laser is not a perfect circle). It is customary to have an elliptical shape.
このため、レーザ光源として半導体レーザを用
いた光学ヘツドにおいては、レーザ光源から対物
レンズに至る光学系の光利用効率を高めることが
必要である。更にデイスクに高密度で情報を記録
するためには、対物レンズに入射する光ビーム
を、その縦横比を等しく、等方的な光ビーム（ビ
ームをその発光方向に対して垂直な方向において
切断したときの断面形状が真円であるような光ビ
ーム）に整形することも必要である。 Therefore, in an optical head using a semiconductor laser as a laser light source, it is necessary to improve the light utilization efficiency of the optical system from the laser light source to the objective lens. Furthermore, in order to record information at high density on a disk, the light beam incident on the objective lens is made into an isotropic light beam (the beam is cut in the direction perpendicular to its emission direction) with equal aspect ratios. It is also necessary to shape the light beam so that its cross-sectional shape is a perfect circle.
従来より、半導体レーザを用いた光学ヘツドに
おいては、光利用効率を高めるために半導体レー
ザから出射する光ビームを開口数の大きなコリメ
ートレンズにより平行な光ビームに変換するとと
もに、コリメートレンズと対物レンズとの光路中
に、非等方的な光ビームを等方的な光ビームに変
換するための補正手段を設けるのが通例である。
このため、従来より第１図及び第２図に示すよう
な光学ヘツドが用いられてきた。 Conventionally, in optical heads using semiconductor lasers, in order to improve light utilization efficiency, the light beam emitted from the semiconductor laser is converted into a parallel light beam by a collimating lens with a large numerical aperture, and the collimating lens and objective lens are It is customary to provide a correction means in the optical path for converting an anisotropic light beam into an isotropic light beam.
For this reason, optical heads as shown in FIGS. 1 and 2 have conventionally been used.
第１図は光ビームの補正手段として整形プリズ
ムを用いた光学ヘツドの斜視図である。第１図に
おいて、半導体レーザ１から放射状に出射した非
等方的な光ビーム１１は、コリメートレンズ２に
より平行光ビーム１２に変換され、整形プリズム
３により縦横に等方性を持つた入射光１３に整形
される。 FIG. 1 is a perspective view of an optical head using a shaping prism as a light beam correction means. In FIG. 1, an anisotropic light beam 11 emitted radially from a semiconductor laser 1 is converted into a parallel light beam 12 by a collimating lens 2, and an incident light beam 13 that is isotropic in the vertical and horizontal directions is converted into a parallel light beam 12 by a shaping prism 3. formatted into.
入射光１３は偏光ビームスプリツタ４の入射面
４ａに入射し、偏光面４ｂを通過した後、第１出
射面４ｃから第１出射光１４として出射する。第
１出射光１４は４分の１波長板５を通過し、対物
レンズ６により集光されてデイスク７に照射され
る。デイスク７による反射光は再び対物レンズ
６、４分の１波長板５を通過して偏光ビームスプ
リツタ４の第１出射面４ｃに入射し、偏光面４ｂ
により反射されて第２出射面４ｄら第２出射光１
５として出射する。第２出射光１５は集光レンズ
８により集束されて円筒レンズ９を通過した後、
検出素子１０に照射される。 The incident light 13 enters the incident surface 4a of the polarizing beam splitter 4, passes through the polarizing surface 4b, and then exits as the first output light 14 from the first output surface 4c. The first emitted light 14 passes through the quarter wavelength plate 5, is focused by the objective lens 6, and is irradiated onto the disk 7. The reflected light from the disk 7 passes through the objective lens 6 and the quarter-wave plate 5 again, enters the first output surface 4c of the polarizing beam splitter 4, and enters the polarizing surface 4b.
The second output light 1 is reflected from the second output surface 4d.
It emits as 5. After the second emitted light 15 is focused by the condensing lens 8 and passes through the cylindrical lens 9,
The detection element 10 is irradiated with light.
上記の構成において、第１出射光１４と第２出
射光１５とは直交するものの、整形プリズム３に
入射する光ビーム１２は上記した第１出射光１４
及び第２出射光１５と互いに斜交するために、半
導体レーザ１及びコリメートレンズ２を、第１図
に示したその他の光学部品に対して斜交させて配
置する必要がある。このため、各光学部品を高精
度で組立てることが難しいという欠点がある。 In the above configuration, although the first output light 14 and the second output light 15 are perpendicular to each other, the light beam 12 incident on the shaping prism 3 is
In order to intersect obliquely with the second emitted light 15, it is necessary to arrange the semiconductor laser 1 and the collimating lens 2 obliquely with respect to the other optical components shown in FIG. Therefore, there is a drawback that it is difficult to assemble each optical component with high precision.
更に、偏光ビームスプリツタ４の入射面４ａに
入射する入射光１３は、ほとんどが偏光面４ｂを
通過して、第１出射面４ｃから出射するものの、
半導体レーザ１から出射する光ビーム１１が完全
な直線偏光ではないために、入射光１３の一部
は、偏光面４ｂで反射され、更に面４ｅで反射さ
れ、再び偏光面４ｂで反射されることによつて、
入射面４ａから出射し、入射光１３と同じ光軸を
逆に辿つて、半導体レーザ１に帰還する。レーザ
の出射光が再びレーザに帰還することは、特に半
導体レーザにおいては、レーザ光に雑音が発生す
るという欠点となる。 Furthermore, although most of the incident light 13 that enters the incident surface 4a of the polarizing beam splitter 4 passes through the polarizing surface 4b and exits from the first exit surface 4c,
Since the light beam 11 emitted from the semiconductor laser 1 is not completely linearly polarized, part of the incident light 13 is reflected by the polarization plane 4b, further reflected by the plane 4e, and then reflected again by the polarization plane 4b. According to
The light is emitted from the incident surface 4a, traces the same optical axis as the incident light 13 in the opposite direction, and returns to the semiconductor laser 1. The fact that the emitted light from the laser returns to the laser again has a disadvantage, especially in semiconductor lasers, in that noise is generated in the laser light.
第２図は光ビームの整形手段として、第１図に
おける整形プリズムの代りに、２枚の円柱レンズ
を用いるようにした従来の光学ヘツドの平面図で
ある。なお、記載されていない光学部品は第１図
に示したものと同様のものを用いる。 FIG. 2 is a plan view of a conventional optical head in which two cylindrical lenses are used as light beam shaping means instead of the shaping prism in FIG. 1. Note that optical components not shown are the same as those shown in FIG. 1.
第２図において、半導体レーザ１ら放射状に出
射した非等方的な光ビーム１１は、コリメートレ
ンズ２により、平行光ビーム１２に変換され、円
柱レンズ２０，２１により、縦横に等方性を持つ
た入射光１３に整形される。入射光１３は偏光ビ
ームスプリツタ４の入射面４ａに入射し、偏光面
４ｂを通過した後、第１出射面４ｃから出射す
る。この第１出射光１４と同じ光軸を逆に戻つて
きたデイスクからの反射光は再び偏光ビームスプ
リツタ４の第１出射面４ｃに入射し、偏光面４ｂ
により反射されて第２出射面４ｄから第２出射光
１５として出射する。第２図の構成においては、
光ビーム１２の光軸と入射光１３の光軸とが一致
しているため、半導体レーザ１及びコリメートレ
ンズ２を光学ヘツドを構成するその他の光学部品
に対して斜交させて配置する必要がないが、部品
点数が増えるとともに、境界面の増加により光量
が減少し、さらに迷光の発生が増加するという欠
点がある。更に、コリメートレンズ２、円筒レン
ズ２０，２１の光軸を正確に一致させ、かつ相互
の位置を正確に配置するためには、組立、調整が
複雑になるという欠点がある。 In FIG. 2, an anisotropic light beam 11 emitted radially from a semiconductor laser 1 is converted into a parallel light beam 12 by a collimating lens 2, and is isotropic in the vertical and horizontal directions by cylindrical lenses 20 and 21. incident light 13. The incident light 13 enters the incident surface 4a of the polarizing beam splitter 4, passes through the polarizing surface 4b, and then exits from the first output surface 4c. The reflected light from the disk that returns along the same optical axis as the first output light 14 enters the first output surface 4c of the polarization beam splitter 4 again, and the polarization surface 4b
The light is reflected by the light beam and exits as second outgoing light 15 from the second outgoing surface 4d. In the configuration shown in Figure 2,
Since the optical axis of the light beam 12 and the optical axis of the incident light 13 coincide, there is no need to arrange the semiconductor laser 1 and the collimating lens 2 obliquely with respect to other optical components constituting the optical head. However, as the number of parts increases, the amount of light decreases due to the increase in the number of boundary surfaces, and the generation of stray light increases. Furthermore, in order to accurately match the optical axes of the collimating lens 2 and the cylindrical lenses 20 and 21 and to accurately arrange their mutual positions, there is a drawback that assembly and adjustment become complicated.
本発明の目的は、上記した従来技術の欠点をな
くし、半導体レーザ光の非等方性を補正できると
ともに、偏光ビームスプリツタへの入射光軸と、
互いに直交する２つの出射光軸のうちの何れか一
方とが互いに平行であり、偏光ビームスプリツタ
の偏光面からの反射面に起因する迷光が半導体レ
ーザに帰還せず、しかも部品点数の少ない光学ヘ
ツドを実現することのできる偏光ビームスプリツ
タを提供することになる。
An object of the present invention is to eliminate the drawbacks of the prior art described above, to correct the anisotropy of semiconductor laser light, and to adjust the optical axis of incidence to a polarizing beam splitter.
An optical system in which one of the two output optical axes orthogonal to each other is parallel to each other, stray light caused by the reflection surface from the polarization plane of the polarization beam splitter does not return to the semiconductor laser, and the number of parts is small. This provides a polarizing beam splitter that can realize a polarizing head.
上記した目的を達成するために、本発明におい
ては、入射面と第１および第２の各出射面と、そ
の内部に偏光面と、前記入射面に入射した光ビー
ムを前記偏光面に導く反射面とをもち、入射面に
光ビームが入射されるのに応じて前記第１および
第２の各出射面から、その出射光軸が相互に直交
する如き第１および第２の各光ビームを出射し、
前記入射面への入射光軸と前記第１および第２の
各出射光軸が同一平面内に位置し、かつ前記入射
光軸と前記第１の出射光軸とが直交し、さらに前
記入射光軸の入射面に対する斜交角に前記入斜光
ビームを非等方性ビームから等方性ビームに整形
するに足る角度をもたせた偏光ビームスプリツタ
において、前記した入射面、反射面、偏光面、第
１出射面、第２出射面の各面以外に、前記入射光
軸に対して平行な面と垂直な面とを備えるととも
に、前記した第１出射面と第１出射光軸および第
２出射面と第２出射光軸とがそれぞれ斜交してい
るようにした。
In order to achieve the above object, the present invention includes an entrance surface, a first and a second exit surface, a polarization plane therein, and a reflection plane that guides the light beam incident on the incidence surface to the polarization plane. and a first and second light beam whose output optical axes are perpendicular to each other from the first and second output surfaces in response to the light beam being incident on the input surface. Emits,
The incident optical axis to the incident surface and each of the first and second output optical axes are located in the same plane, and the incident optical axis and the first output optical axis are perpendicular to each other, and the incident light In a polarizing beam splitter in which the oblique angle of the axis with respect to the incident plane is sufficient to shape the incident oblique beam from an anisotropic beam to an isotropic beam, the above-mentioned incident plane, reflective surface, polarizing plane, In addition to the first output surface and the second output surface, the first output surface, the first output optical axis, and the second output surface are provided with a surface parallel to the incident optical axis and a perpendicular surface to the incident optical axis. and the second output optical axis are arranged to be oblique to each other.
以下、本発明の詳細を図に示す実施例により説
明する。第３図は、本発明の一実施例としての偏
光ビームスプリツタを用いた光学ヘツドの斜視図
である。
Hereinafter, details of the present invention will be explained with reference to embodiments shown in the drawings. FIG. 3 is a perspective view of an optical head using a polarizing beam splitter as an embodiment of the present invention.
第３図において、半導体レーザ１から放射状に
出射した非等方的な光ビーム１１は、コリメート
レンズ２により平行光ビームである入射光１２に
変換され、偏光ビームスプリツタ３０の入射面３
０ａに斜めに入射することによつて縦横に等方性
を持つた光ビーム１３に整形され、偏光ビームス
プリツタ３０内面の反射面３０ｂにより反射され
て、入射光ビーム１２の光軸と直交する光ビーム
１６となり、偏光面３０ｃを通過し、第１出射光
１４として第１出射面３０ｄより、該出射面３０
ｄに斜交して出射する。 In FIG. 3, an anisotropic light beam 11 emitted radially from a semiconductor laser 1 is converted into an incident light beam 12 which is a parallel light beam by a collimating lens 2, and is converted into an incident light beam 12 which is a parallel light beam.
By obliquely entering the beam 0a, it is shaped into a light beam 13 that is isotropic in the vertical and horizontal directions, and is reflected by the reflective surface 30b on the inner surface of the polarizing beam splitter 30, so that it is perpendicular to the optical axis of the incident light beam 12. It becomes a light beam 16, passes through the polarization plane 30c, and is emitted from the first emission surface 30d as the first emission light 14 from the emission surface 30.
It emits obliquely to d.
第１出射光１４は４分の１波長板５を通過し、
対物レンズ６により集光されて、デイスク７に照
射される。デイスク７による反射光は再び対物レ
ンズ６、４分の１波長板５を通過し、偏光ビーム
スプリツタ３０の第１出射面３０ｄに斜交して入
射し、偏光面３０ｃにより反射され、第２出射面
３０ｅから、第１出射光１４に直交する第２出射
光１５として、該第２出射面３０ｅに斜交して出
射する。第２出射光１５は集光レンズ８により収
束光ビーム１６となり、円筒レンズ９を通過した
後、検出素子１０に照射される。 The first emitted light 14 passes through a quarter wavelength plate 5,
The light is focused by the objective lens 6 and irradiated onto the disk 7 . The reflected light from the disk 7 passes through the objective lens 6 and the quarter-wave plate 5 again, obliquely enters the first output surface 30d of the polarizing beam splitter 30, is reflected by the polarizing surface 30c, and is reflected by the second polarizing surface 30c. From the output surface 30e, the second output light 15 that is orthogonal to the first output light 14 is output obliquely to the second output surface 30e. The second emitted light 15 becomes a convergent light beam 16 by the condensing lens 8, passes through the cylindrical lens 9, and then is irradiated onto the detection element 10.
第４図は、第３図における偏光ビームスプリツ
タ３０のみを第３図に示す矢印Ａ方向から見た平
面図である。 4 is a plan view of only the polarizing beam splitter 30 in FIG. 3 viewed from the direction of arrow A in FIG. 3. FIG.
第４図の構成において、半導体レーザの波長に
おける偏光ビームスプリツタ３０の光屈折率をｎ
とし、光ビームの非等方性を補正するための紙面
に平行な面内における光ビーム１２の拡大率をｍ
とすると、スプリツタ３０における図示の角θ1は
次の式(1)、角θ2は同じく式(2)で表わされる角度と
なる。 In the configuration shown in FIG. 4, the optical refractive index of the polarizing beam splitter 30 at the wavelength of the semiconductor laser is n.
The magnification factor of the light beam 12 in the plane parallel to the paper surface for correcting the anisotropy of the light beam is m
Then, the illustrated angle θ 1 in the splitter 30 is expressed by the following equation (1), and the angle θ 2 is also expressed by the equation (2).
θ1＝1＋45゜ (1)
θ2＝（2−1）／２＋90゜ (2)
2＝sin-1（sin（1）／ｎ） (4)
なお、上記の構成においては、角θ3≠θ4、入射
面３０ａに対する入射光１２の入射角は1であ
り、入射光ビーム１２は紙面に平行な方向よりも
紙面に垂直な方向に長い断面形状を成しているも
のとする。 θ 1 = 1 + 45° (1) θ 2 = ( 2 − 1 ) / 2 + 90° (2) 2 = sin -1 (sin ( 1 )/n) (4) In the above configuration, the angle θ 3 ≠ θ 4 , the incident angle of the incident light 12 with respect to the incident surface 30a is 1 , and the incident light beam 12 is assumed to have a cross-sectional shape that is longer in the direction perpendicular to the paper than in the direction parallel to the paper.
例えばプリズムの屈折率ｎ＝1.51のとき、拡大
率ｍ＝2.40とすると、θ1＝116.05゜、θ2＝73.87゜に
すれば縦：横＝１：2.40の非等方性のある光ビー
ム１２の偏光ビームプリツタ３０への入射光軸
と、互いに直交する２つの出射光軸１４，１５、
のうちの一方である出射光軸１５とが互いに平行
になり、かつ等方性のある光ビーム１３を得るこ
とができる。 For example, if the refractive index of the prism is n = 1.51 and the magnification m = 2.40, then if θ 1 = 116.05° and θ 2 = 73.87°, the light beam 12 will have an anisotropy of vertical:horizontal = 1:2.40. an input optical axis to the polarized beam splitter 30, and two output optical axes 14, 15 that are orthogonal to each other.
The output optical axes 15, which are one of the two, are parallel to each other, and an isotropic light beam 13 can be obtained.
以上説明した如き構成により偏光ビームスプリ
ツタ３０では、光ビーム１６の一部は偏光面３０
ｃで反射するものの、該反射光は入射面３０ａへ
は、光ビーム１３と異なつた角度で入射するため
に、半導体レーザ１に帰還することはない。 With the configuration described above, in the polarizing beam splitter 30, a part of the light beam 16 is
Although reflected at point c, the reflected light does not return to the semiconductor laser 1 because it enters the incident surface 30a at a different angle from the light beam 13.
また平行光ビーム１２、出射光ビーム１５はデ
イスク７と並行になるため薄型な光学ヘツドの構
成が可能となる。しかも、光ビームの通過または
反射する境界面の数は、第１図に示した従来の光
学ヘツドの同等の機能を果たす部分よりも１つ減
り、また第２図に示す従来の光学ヘツドよりも３
つ減つているので、迷光の問題も軽減され、さら
に反射面３０ｂに反射コーテイングを施すことに
より、光利用率も向上する。 Further, since the parallel light beam 12 and the output light beam 15 are parallel to the disk 7, it is possible to construct a thin optical head. Moreover, the number of interfaces through which the light beam passes or is reflected is one less than the equivalent functional parts of the conventional optical head shown in FIG. 3
Since the number of lights is reduced, the problem of stray light is also alleviated, and by applying a reflective coating to the reflective surface 30b, the light utilization efficiency is also improved.
なお第４図において、第１出射光１４と第１出
射面３０ｄが直交せず、また同様に第２出射光１
５と第２出射面３０ｅが直交しないように、角度
θ1、θ2、θ3、θ4の値を定めていることが認めされ
るであろう。 Note that in FIG. 4, the first output light 14 and the first output surface 30d do not intersect at right angles, and similarly the second output light 14 and the first output surface 30d do not intersect at right angles.
It will be recognized that the values of the angles θ 1 , θ 2 , θ 3 , and θ 4 are determined so that the angles 5 and the second exit surface 30e are not perpendicular to each other.
以上の構成によつて光ビーム１６の第１出射面
３０ｄによる反射光が存在しても、該反射光は光
ビーム１６と同じ光軸を逆に辿ることはなくな
る。また、以上の事柄は第２出射面３０ｅについ
ても同様である。 With the above configuration, even if there is light reflected by the first output surface 30d of the light beam 16, the reflected light will not trace the same optical axis as the light beam 16 in the opposite direction. Moreover, the above matters also apply to the second exit surface 30e.
以上説明したように、従来の偏光ビームスプリ
ツタを用いた光学ヘツドにおいては、偏光面から
の反射光が半導体レーザに帰還してノイズが発生
するとともに、非等方的な光ビームの補正にプリ
ズムを用いた場合は入射光軸と出射光軸とが斜交
して光学部品を高精度で組立てることが困難であ
り、また２個の円筒レンズにより光ビームを補正
した場合は、入射光と出射光とは直交または平行
であるものの、光学部品の数が増加するととも
に、各光学部品の組立てに更に高い精度が要求さ
れるという欠点があつたが、本発明による偏光ビ
ームスプリツタを用いた光学ヘツドにおいては、
非等方性の光ビームを補正するためのプリズムと
偏光ビームスプリツタとを一体化して新たな偏光
ビームスプリツタとし、そのプリズム部分で補正
された光ビームをスプリツタ部分へ導くための反
射面（第４図３０ｂ）を設けるとともに、入射光
軸と入射面とを適当に斜交させることにより、入
射光軸と相互に直交する２つの出射光軸のうちの
一方とが直交、他方とが平行となり、かつ偏光面
からの反射光が半導体レーザに帰還することがな
いために、上記した従来技術の欠点を解決し得た
ものである。さらに補正用プリズムとスプリツタ
との一体化により、光ビームの通過する境界面数
が少なくなるため、光利用率も向上し、また光学
ヘツド部分を薄型化できるという効果もある。
As explained above, in an optical head using a conventional polarizing beam splitter, the reflected light from the polarizing plane returns to the semiconductor laser and generates noise, and the prism is used to correct the anisotropic light beam. When using a cylindrical lens, it is difficult to assemble optical components with high precision because the incident optical axis and the output optical axis intersect obliquely, and when the light beam is corrected with two cylindrical lenses, the incident light and the output optical axis are Although the incident light is perpendicular or parallel to the incident light, it has the disadvantage that the number of optical components increases and higher precision is required for assembling each optical component. In the head,
A prism for correcting an anisotropic light beam and a polarizing beam splitter are integrated to form a new polarizing beam splitter, and a reflecting surface ( 30b) in Fig. 4, and by appropriately making the incident optical axis and the incident surface obliquely intersect, the incident optical axis and one of the two mutually orthogonal output optical axes are perpendicular, and the other is parallel. Since the reflected light from the polarization plane does not return to the semiconductor laser, the above-mentioned drawbacks of the prior art can be solved. Furthermore, by integrating the correction prism and the splitter, the number of boundary surfaces through which the light beam passes is reduced, so that the light utilization efficiency is improved and the optical head portion can also be made thinner.
第１図は光学ヘツドの従来例を示す斜視図、第
２図は同じく他の従来例を示す説明図、第３図は
本発明の一実施例を含む光学ヘツドを示す斜視
図、第４図は第３図における偏光ビームスプリツ
タ３０（本発明の一実施例）を矢印Ａ方向から見
た平面図、である。
符号説明、１……半導体レーザ、２……コリメ
ートレンズ、５……1/4波長板、６……対物レン
ズ、７……デイスク、８……集光レンズ、９……
円柱レンズ、１０……検出素子、３０……偏光ビ
ームスプリツタ。
FIG. 1 is a perspective view showing a conventional example of an optical head, FIG. 2 is an explanatory view showing another conventional example, FIG. 3 is a perspective view showing an optical head including an embodiment of the present invention, and FIG. is a plan view of the polarizing beam splitter 30 (an embodiment of the present invention) in FIG. 3, viewed from the direction of arrow A. Description of symbols, 1...Semiconductor laser, 2...Collimating lens, 5...1/4 wavelength plate, 6...Objective lens, 7...Disc, 8...Condensing lens, 9...
Cylindrical lens, 10...detection element, 30...polarized beam splitter.
Claims (1)
内部に偏光面と、前記入射面に入射した光ビーム
を前記偏光面に導く反射面とをもち、入射面に光
ビームが入射されるのに応じて前記第１および第
２の各出射面から、その出射光軸が相互に直交す
る如き第１および第２の各光ビームを出射し、前
記入射面への入射光軸と前記第１および第２の各
出射光軸が同一平面内に位置し、かつ前記入射光
軸と前記第１の出射光軸とが直交し、さらに前記
入射光軸の入射面に対する斜交角に前記入射光ビ
ームを非等方性ビームから等方性ビームに整形す
るに足る角度をもたせた偏光ビームスプリツタに
おいて、 前記した入射面、反射面、偏光面、第１出射
面、第２出射面の各面以外に、前記入射光軸に対
して平行な面と垂直な面とを備えるとともに、前
記した第１出射面と第１出射光軸および第２出射
面と第２出射光軸とがそれぞれ斜交している偏光
ビームスプリツタ。[Scope of Claims] 1. An incident surface having an entrance surface, a first and a second exit surface, a polarization surface therein, and a reflection surface that guides the light beam incident on the entrance surface to the polarization surface, In response to the light beam being incident on the light beam, the first and second light beams are emitted from the first and second light emitting surfaces so that their light emitting axes are orthogonal to each other, and the light beams are directed to the light incident surface. The incident optical axis and each of the first and second output optical axes are located in the same plane, and the incident optical axis and the first output optical axis are perpendicular to each other, and the incident plane of the input optical axis is In the polarizing beam splitter, the incident light beam has an oblique angle sufficient to shape the incident light beam from an anisotropic beam to an isotropic beam, the above-mentioned incident surface, reflective surface, polarizing surface, first exit surface, In addition to the respective surfaces of the second output surface, the first output surface and the first output optical axis, and the second output surface and the second output surface are provided. A polarizing beam splitter whose emission axes are oblique to each other.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58062989A JPS59188852A (en) | 1983-04-12 | 1983-04-12 | Polarized beam splitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58062989A JPS59188852A (en) | 1983-04-12 | 1983-04-12 | Polarized beam splitter |
Related Child Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP61206882A Division JPS6278743A (en) | 1986-09-04 | 1986-09-04 | Optical head |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59188852A JPS59188852A (en) | 1984-10-26 |
| JPH0533466B2 true JPH0533466B2 (en) | 1993-05-19 |
Family
ID=13216280
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58062989A Granted JPS59188852A (en) | 1983-04-12 | 1983-04-12 | Polarized beam splitter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59188852A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS59195345A (en) * | 1983-04-20 | 1984-11-06 | Matsushita Electric Ind Co Ltd | Optical head |
| JP3607836B2 (en) * | 1999-03-31 | 2005-01-05 | シャープ株式会社 | Optical pickup device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5528590A (en) * | 1972-10-24 | 1980-02-29 | Mca Disco Vision | Information reading device in video disk player and method thereof |
| JPS59128510A (en) * | 1983-01-12 | 1984-07-24 | Toyo Commun Equip Co Ltd | Beam pattern shaping device of polarized light beam splitter |
| JPS59129950A (en) * | 1983-01-12 | 1984-07-26 | Matsushita Electric Ind Co Ltd | Optical pickup |
-
1983
- 1983-04-12 JP JP58062989A patent/JPS59188852A/en active Granted
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5528590A (en) * | 1972-10-24 | 1980-02-29 | Mca Disco Vision | Information reading device in video disk player and method thereof |
| JPS59128510A (en) * | 1983-01-12 | 1984-07-24 | Toyo Commun Equip Co Ltd | Beam pattern shaping device of polarized light beam splitter |
| JPS59129950A (en) * | 1983-01-12 | 1984-07-26 | Matsushita Electric Ind Co Ltd | Optical pickup |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59188852A (en) | 1984-10-26 |
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