JP2010020855A

JP2010020855A - Reflection type diffraction grating for a plurality of wavelengths and optical pickup device including the same

Info

Publication number: JP2010020855A
Application number: JP2008181888A
Authority: JP
Inventors: Nobuji Kawamura; 宜司川村
Original assignee: Fujinon Corp
Current assignee: Fujinon Corp
Priority date: 2008-07-11
Filing date: 2008-07-11
Publication date: 2010-01-28

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a low-cost reflection type diffraction grating for a plurality of wavelengths which allows a desired diffraction efficiency and diffraction direction to be set for each wavelength and matches three or more multiple wavelengths. <P>SOLUTION: The reflection type diffraction grating for the plurality of wavelengths is formed by layering a first reflection type diffracting grating 10, a second reflection type diffraction grating 20 and a third reflection type diffraction grating 30 in this order on a substrate 3. The first reflection type diffraction grating 10 has first reflection diffracting layers 12 reflecting and diffracting a first light beam of first to third light beams having wavelengths different from each other and transmitting other light beams and first phase adjusting layers 13 adjusting a phase of a wavefront of at least the second light beam of the transmitted second and third light beams. The second reflection type diffraction grating 20 has second reflection diffracting layers 22 reflecting and diffracting the second light beam and transmitting the third light beam and second phase adjusting layers 23 adjusting a phase of a wavefront of the transmitted third light beam. The third reflection type diffraction grating 30 has third reflection diffracting layers 32 reflecting and diffracting the third light beam. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

本発明は、互いに異なる波長帯域に属する複数個の光ビームが選択的に出力される光路上において、各々の光ビームを所定の方向に反射回折せしめるために配設される複数波長用反射型回折格子およびこれを備えた光ピックアップ装置に関する。 The present invention provides a reflection diffraction for multiple wavelengths arranged to reflect and diffract each light beam in a predetermined direction on an optical path where a plurality of light beams belonging to different wavelength bands are selectively output. The present invention relates to a grating and an optical pickup device including the same.

従来、ＣＤやＤＶＤ等の光記録媒体に対するデータの記録および／または再生用の光ピックアップ装置において、トラッキング制御や出力光のパワー制御等を行うために回折格子が用いられている。
このような回折格子として、ＣＤ用およびＤＶＤ用等の互いに異なる波長帯域に属する２つの光ビームに対し共用される２波長対応型のものが知られている（下記特許文献１〜４参照）。 Conventionally, in an optical pickup device for recording and / or reproducing data on an optical recording medium such as a CD or a DVD, a diffraction grating is used for tracking control, power control of output light, and the like.
As such a diffraction grating, there is known a two-wavelength compatible type shared by two light beams belonging to different wavelength bands such as for CD and DVD (see Patent Documents 1 to 4 below).

下記特許文献１、２に記載された回折格子は、透明な基板の両面に互いに異なる回折格子を形成したものであり（以下「両面タイプ」と称する）、基板の一方の面に形成された回折格子は、２つの光ビームのうちの一方のみを回折し、基板の他方の面に形成された回折格子は、２つの光ビームのうちの他方のみを回折するように構成されている。 The diffraction gratings described in the following Patent Documents 1 and 2 are obtained by forming different diffraction gratings on both surfaces of a transparent substrate (hereinafter referred to as “double-sided type”), and diffraction formed on one surface of the substrate. The grating is configured to diffract only one of the two light beams, and the diffraction grating formed on the other surface of the substrate is configured to diffract only the other of the two light beams.

下記特許文献３に記載された回折格子は、透明基板の片面領域を２群に分け、各群の領域に互いに異なる回折格子をそれぞれ形成したものであり（以下「片面タイプ」と称する）、２群の領域のうちの一方の群の領域に形成された回折格子は、２つの光ビームのうちの一方のみを回折し、他方の群の領域に形成された回折格子は、２つの光ビームのうちの他方のみを回折するように構成されている。 The diffraction grating described in the following Patent Document 3 is obtained by dividing a single-sided region of a transparent substrate into two groups and forming different diffraction gratings in each grouped region (hereinafter referred to as “single-sided type”). A diffraction grating formed in one of the group regions diffracts only one of the two light beams, and a diffraction grating formed in the other group of the two light beams Only the other of them is diffracted.

下記特許文献４に記載された回折格子は、光ビームの波長および偏光状態に応じて回折作用が異なるようにするために、複屈折材料を用いて形成されている。 The diffraction grating described in the following Patent Document 4 is formed using a birefringent material so that the diffractive action differs depending on the wavelength and polarization state of the light beam.

特開２００３−６８９１号公報JP 2003-6891 A 特開２００７−３３４９７５号公報JP 2007-334975 A 特開２００４−３２７００５号公報JP 2004-327005 A 国際公開ＷＯ２００４／０９７８１９International Publication WO2004 / 097819

上述の両面タイプの回折格子は、回折効率の波長依存性が大きく、波長毎に所望の回折効率を得ることが困難である。また、近年、青色光域の光ビームを用いるブルーレイディスク（ＢＤ）が実用化されており、これに伴い３波長対応型の回折格子の実用化も望まれているが、両面タイプの回折格子によりこれを実現することは困難である。 The double-sided diffraction grating described above has a large wavelength dependency of diffraction efficiency, and it is difficult to obtain a desired diffraction efficiency for each wavelength. In recent years, Blu-ray Discs (BD) using a light beam in the blue light range have been put into practical use, and along with this, the practical application of a three-wavelength compatible diffraction grating is desired. It is difficult to realize this.

また、上述の片面タイプの回折格子では、３波長対応型のものも提案されているが、不要な回折光が生じ易く、また波長毎に所望の回折方向を設定することが困難である。
また、複屈折材料を用いる回折格子は高価であるため、製造コストが嵩むという問題がある。 Further, although the above-mentioned single-sided diffraction grating has been proposed for three wavelengths, unnecessary diffracted light is likely to be generated, and it is difficult to set a desired diffraction direction for each wavelength.
Moreover, since the diffraction grating using a birefringent material is expensive, there exists a problem that manufacturing cost increases.

本発明は上記事情に鑑みなされたものであり、波長毎に所望の回折効率および回折方向を設定することが可能であり、かつ３波長以上の多波長にも対応可能な低コストの複数波長用反射型回折格子およびこれを備えた光ピックアップ装置を提供することを目的とする。 The present invention has been made in view of the above circumstances, and it is possible to set a desired diffraction efficiency and diffraction direction for each wavelength, and it can be used for a plurality of wavelengths at a low cost capable of dealing with multiple wavelengths of three or more wavelengths. It is an object of the present invention to provide a reflective diffraction grating and an optical pickup device including the same.

本発明に係る複数波長用反射型回折格子は、第１から第ＮまでのＮ個（Ｎは２以上の整数）の互いに異なる波長帯域にそれぞれ属する第１から第ＮまでのＮ個の光ビームが、選択的に出力される光路上に配設される複数波長用反射型回折格子であって、
第１から第ＮまでのＮ個の反射型回折格子が、前記Ｎ個の光ビームの入射側からこの順に積層され、
第ｊ反射型回折格子（ｊは１からＮ−１までの任意の整数）は、該第ｊ反射型回折格子に入射した第ｊ光ビームから第Ｎ光ビームまでのうち該第ｊ光ビームは反射回折せしめ他の光ビームは透過せしめる第ｊ反射回折層を有してなり、
第Ｎ反射型回折格子は、該第Ｎ反射型回折格子に入射した前記第Ｎ光ビームを反射回折せしめる第Ｎ反射回折層を有してなり、
前記第ｊ反射型回折格子は、該第ｊ反射型回折格子を透過する第（ｊ＋１）光ビームから前記第Ｎ光ビームまでのうち少なくとも該第（ｊ＋１）光ビームの波面の位相を整える第ｊ位相調整層を有してなる、ことを特徴とする。 The multi-wavelength reflective diffraction grating according to the present invention includes first to Nth light beams belonging to first to Nth (N is an integer of 2 or more) different wavelength bands, respectively. Is a reflective diffraction grating for a plurality of wavelengths disposed on a selectively output optical path,
N reflective diffraction gratings from 1 to N are stacked in this order from the incident side of the N light beams,
The jth reflection type diffraction grating (j is an arbitrary integer from 1 to N-1) is the jth light beam out of the jth light beam to the Nth light beam incident on the jth reflection type diffraction grating. A j-th reflection diffractive layer for reflecting and diffracting other light beams;
The Nth reflection type diffraction grating has an Nth reflection diffraction layer for reflecting and diffracting the Nth light beam incident on the Nth reflection type diffraction grating,
The jth reflection type diffraction grating adjusts the phase of the wavefront of at least the (j + 1) th light beam from the (j + 1) th light beam to the Nth light beam transmitted through the jth reflection type diffraction grating. It has a phase adjustment layer.

ここで、前記第ｊ反射回折層は、第ｊ波長帯域の光から第Ｎ波長帯域の光までのうち該第ｊ波長帯域の光は反射せしめ他の波長帯域の光は透過せしめる特性を有する第ｊダイクロイック膜を、周期的な凹凸状に配設してなるものであり、
前記第Ｎ反射回折層は、前記第Ｎ波長帯域の光を反射せしめる特性を有する第Ｎダイクロイック膜または全反射膜を、周期的な凹凸状に配設してなるものである、とすることができる。 Here, the j-th reflection diffraction layer has a characteristic of reflecting light in the j-th wavelength band and transmitting light in other wavelength bands from light in the j-th wavelength band to light in the N-th wavelength band. j dichroic film is arranged in a periodic uneven shape,
The Nth reflection diffractive layer is formed by periodically disposing an Nth dichroic film or a total reflection film having a characteristic of reflecting light in the Nth wavelength band. it can.

また、前記第ｊ反射型回折格子と第（ｊ＋１）反射型回折格子との間に、第（ｊ＋１）反射回折層により反射回折せしめられた第（ｊ＋１）光ビームの０次回折光の軸の位置を、前記第ｊ反射回折層により反射回折せしめられた前記第ｊ光ビームの０次回折光の軸の位置に一致させる第ｊ軸位置調整層が設けられている、とすることができる。 Further, the position of the axis of the 0th-order diffracted light beam of the (j + 1) th light beam reflected and diffracted by the (j + 1) th reflection diffraction layer between the jth reflection type diffraction grating and the (j + 1) th reflection type diffraction grating. Is provided with a j-th axis position adjustment layer that matches the position of the 0th-order diffracted light axis of the j-th light beam reflected and diffracted by the j-th reflection diffraction layer.

また、特に３波長対応型としての、本発明に係る複数波長用反射型回折格子は、第１波長帯域に属する第１光ビームと、該第１波長帯域とは異なる第２波長帯域に属する第２光ビームと、該第１波長帯域および該第２波長帯域とは異なる第３波長帯域に属する第３光ビームとが、選択的に出力される光路上に配設される複数波長用反射型回折格子であって、
第１反射型回折格子と第２反射型回折格子と第３反射型回折格子とが、前記第１光ビーム、前記第２光ビームおよび前記第３光ビームの入射側からこの順に積層され、
前記第１反射型回折格子は、該第１反射型回折格子に入射した前記第１光ビームから前記第３光ビームまでのうち該第１光ビームは反射回折せしめ他の光ビームは透過せしめる第１反射回折層と、透過せしめた前記第２光ビームおよび前記第３光ビームのうち少なくとも該第２光ビームの波面の位相を整える第１位相調整層とを有してなり、
前記第２反射型回折格子は、該第２反射型回折格子に入射した前記第２光ビームと前記第３光ビームのうち該第２光ビームは反射回折せしめ該第３光ビームは透過せしめる第２反射回折層と、透過せしめた該第３光ビームの波面の位相を整える第２位相調整層とを有してなり、
前記第３反射型回折格子は、該第３反射型回折格子に入射した前記第３光ビームを反射回折せしめる第３反射回折層を有してなり、
前記第１反射回折層は、前記第１波長帯域の光は反射せしめ前記第２波長帯域の光および前記第３波長帯域の光は透過せしめる特性を有する第１ダイクロイック膜を、周期的な凹凸状に配設してなるものであり、
前記第２反射回折層は、前記第２波長帯域の光は反射せしめ前記第３波長帯域の光は透過せしめる特性を有する第２ダイクロイック膜を、周期的な凹凸状に配設してなるものであり、
前記第３反射回折層は、前記第３波長帯域の光を反射せしめる特性を有する第３ダイクロイック膜または全反射膜を周期的な凹凸状に配設してなるものである、ことを特徴とするものである。 Further, the reflective diffraction grating for multiple wavelengths according to the present invention, particularly as a three-wavelength compatible type, includes a first light beam belonging to the first wavelength band and a second wavelength band belonging to a second wavelength band different from the first wavelength band. A reflection type for multiple wavelengths in which two light beams and a third light beam belonging to a third wavelength band different from the first wavelength band and the second wavelength band are selectively output. A diffraction grating,
A first reflective diffraction grating, a second reflective diffraction grating, and a third reflective diffraction grating are stacked in this order from the incident side of the first light beam, the second light beam, and the third light beam,
The first reflection type diffraction grating reflects and diffracts the first light beam among the first light beam to the third light beam incident on the first reflection type diffraction grating and transmits the other light beam. A reflection diffraction layer, and a first phase adjustment layer for adjusting a phase of a wave front of at least the second light beam of the transmitted second light beam and the third light beam,
The second reflection type diffraction grating reflects and diffracts the second light beam of the second light beam and the third light beam incident on the second reflection type diffraction grating and transmits the third light beam. A second reflection diffraction layer and a second phase adjustment layer for adjusting the phase of the wavefront of the transmitted third light beam,
The third reflective diffraction grating has a third reflective diffraction layer that reflects and diffracts the third light beam incident on the third reflective diffraction grating,
The first reflective diffractive layer has a periodic concavo-convex shape on a first dichroic film having a characteristic of reflecting light in the first wavelength band and transmitting light in the second wavelength band and light in the third wavelength band. It is arranged in the
The second reflection diffraction layer is formed by arranging a second dichroic film having a characteristic of reflecting the light of the second wavelength band and transmitting the light of the third wavelength band in a periodic uneven shape. Yes,
The third reflective diffractive layer is formed by arranging a third dichroic film or a total reflection film having a characteristic of reflecting the light in the third wavelength band in a periodic uneven shape. Is.

ここで、前記第１反射型回折格子と前記第２反射型回折格子との間に、前記第２反射回折層により反射回折せしめられた前記第２光ビームの０次回折光の軸の位置を、前記第１反射回折層により反射回折せしめられた前記第１光ビームの０次回折光の軸の位置に一致させる第１軸位置調整層が設けられ、
前記第２反射型回折格子と前記第３反射型回折格子との間に、前記第３反射回折層により反射回折せしめられた前記第３光ビームの０次回折光の軸の位置を、前記第２反射回折層により反射回折せしめられた前記第２光ビームの０次回折光の軸の位置に一致させる第２軸位置調整層が設けられている、とすることができる。 Here, the position of the axis of the 0th-order diffracted light of the second light beam reflected and diffracted by the second reflective diffraction layer between the first reflective diffraction grating and the second reflective diffraction grating, A first axis position adjusting layer is provided to match the position of the axis of the 0th-order diffracted light of the first light beam reflected and diffracted by the first reflective diffraction layer;
The position of the axis of the 0th-order diffracted light beam of the third light beam reflected and diffracted by the third reflective diffraction layer between the second reflective diffraction grating and the third reflective diffraction grating is defined as the second reflective diffraction grating. It can be assumed that a second axis position adjusting layer is provided that matches the position of the axis of the 0th-order diffracted light of the second light beam reflected and diffracted by the reflection diffraction layer.

また、本発明に係る光ピックアップ装置は、上述の本発明に係る複数波長用反射型回折格子を備えてなることを特徴とするものである。 An optical pickup device according to the present invention includes the above-described reflection diffraction grating for multiple wavelengths according to the present invention.

本発明に係る複数波長用反射型回折格子は、属する波長帯域が互いに異なるＮ個の光ビームにそれぞれ対応するＮ個の反射型回折格子を積層してなるものであり、各々の光ビームは、対応する所定の反射型回折格子において反射回折され、その反射型回折格子よりも入射側の位置に配設された他の反射型回折格子は透過するように構成されている。また、第ｊ反射型回折格子を透過する第（ｊ＋１）光ビームから第Ｎ光ビームまでのうち少なくとも該第（ｊ＋１）光ビームは、第ｊ反射型回折格子が有する第ｊ位相調整層により波面の位相を整えられて、次の第（ｊ＋１）反射型回折格子に入射するようになっている。 The multi-wavelength reflection diffraction grating according to the present invention is formed by stacking N reflection diffraction gratings corresponding to N light beams having different wavelength bands, and each light beam includes: The other reflection type diffraction gratings are reflected and diffracted by a corresponding predetermined reflection type diffraction grating, and are disposed at a position closer to the incident side than the reflection type diffraction grating. In addition, at least the (j + 1) th light beam from the (j + 1) th light beam to the Nth light beam transmitted through the jth reflection type diffraction grating is wavefronted by the jth phase adjustment layer of the jth reflection type diffraction grating. Are adjusted to be incident on the next (j + 1) th reflective diffraction grating.

このように、Ｎ個の反射型回折格子を積層するとともに、各々の反射型回折格子において反射回折層および位相調整層を設けてなる本発明に係る複数波長用反射型回折格子によれば、各反射型回折格子における反射回折層と位相調整層を適宜形成することにより、各々の光ビームに対する回折効率および回折方向を所望の値に設定することが可能となる。 As described above, according to the reflection diffraction grating for a plurality of wavelengths according to the present invention in which N reflection diffraction gratings are stacked and each of the reflection diffraction gratings is provided with a reflection diffraction layer and a phase adjustment layer, By appropriately forming the reflection diffraction layer and the phase adjustment layer in the reflection type diffraction grating, the diffraction efficiency and the diffraction direction for each light beam can be set to desired values.

また、各々の反射型回折格子における反射回折層と位相調整層は、汎用性のある一般的な膜材料を用いて形成することができるので、複屈折材料を用いた回折格子と比較して本発明に係る複数波長用反射型回折格子は、低コストで作製することが可能となる。 In addition, the reflection diffraction layer and the phase adjustment layer in each reflection type diffraction grating can be formed using a general-purpose film material having general versatility, so this is compared with a diffraction grating using a birefringent material. The reflective diffraction grating for multiple wavelengths according to the invention can be manufactured at low cost.

また、本発明に係る光ピックアップ装置によれば、互いに異なる複数（特に３以上の）波長帯域の光ビームを用いて、各光ビームに対応した光記録媒体へのデータの記録や再生を行う際のトラッキング制御等を、本発明に係る複数波長用反射型回折格子を用いて高精度に行うことが可能となる。 In addition, according to the optical pickup device of the present invention, when recording and reproducing data on an optical recording medium corresponding to each light beam using light beams of a plurality of (especially three or more) wavelength bands different from each other. Tracking control and the like can be performed with high accuracy using the reflection diffraction grating for multiple wavelengths according to the present invention.

以下、本発明の実施形態について図面を参照しつつ詳細に説明する。図１は本発明の第１実施形態に係る複数波長用反射型回折格子の概略構成を示す断面図である。 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a sectional view showing a schematic configuration of a reflection diffraction grating for multiple wavelengths according to a first embodiment of the present invention.

図１に示す第１実施形態の複数波長用反射型回折格子１は、第１波長帯域（例えば、青色光帯域）に属する第１光ビーム（例えば、波長４０５ｎｍ）と、第２波長帯域（例えば、緑色光帯域）に属する第２光ビーム（例えば、波長６５５ｎｍ）と、第３波長帯域（例えば、赤色光帯域または近赤外光帯域）に属する第３光ビーム（例えば、波長７８５ｎｍ）とが、選択的に出力される光路上に配設される３波長対応型のものであり、光学硝材等により形成される透明な基板３上に、第１反射型回折格子１０、第２反射型回折格子２０および第３反射型回折格子３０が上記各光ビームの入射側（基板３側）からこの順に積層されてなる。 A multi-wavelength reflective diffraction grating 1 of the first embodiment shown in FIG. 1 includes a first light beam (for example, a wavelength of 405 nm) belonging to a first wavelength band (for example, a blue light band) and a second wavelength band (for example, a blue wavelength band). A second light beam (for example, wavelength 655 nm) belonging to the green light band) and a third light beam (for example, wavelength 785 nm) belonging to the third wavelength band (for example, red light band or near infrared light band). The first reflection type diffraction grating 10 and the second reflection type diffraction are provided on a transparent substrate 3 formed of an optical glass material, etc. The grating 20 and the third reflection type diffraction grating 30 are laminated in this order from the light incident side (substrate 3 side).

上記第１反射型回折格子１０は、上記基板３上に形成された第１ベース層１１（具体的には例えば、厚さ５０〜１００ｎｍ程度のＳｉＯ_２の単一層からなる）を介して、図中左右方向に周期的な凹凸を形成するように設けられた第１反射回折層１２と、該第１反射回折層１２上に形成された第１位相調整層１３とを備えてなる。なお、第１ベース層１１、第１反射回折層１２および第１位相調整層１３は、図中左右方向に周期的な構成を有しており、番号はそれらの一部のみに付している。 The first reflective diffraction grating 10 is formed through a first base layer 11 (specifically, for example, a single layer of SiO _{2 having} a thickness of about 50 to 100 nm) formed on the substrate 3. The first reflection diffraction layer 12 is provided so as to form periodic irregularities in the middle and right and left directions, and the first phase adjustment layer 13 is formed on the first reflection diffraction layer 12. In addition, the 1st base layer 11, the 1st reflection diffraction layer 12, and the 1st phase adjustment layer 13 have a periodic structure in the left-right direction in a figure, and the number is attached | subjected only to those parts. .

上記第１反射回折層１２は、第１反射型回折格子１０に入射した上記各光ビームのうち第１光ビームは所定方向に反射回折せしめ他の光ビームは透過せしめるように形成されたものであり、具体的にはＴｉＯ_２とＳｉＯ_２との交互層からなる第１ダイクロイック膜から構成されている。 The first reflection diffraction layer 12 is formed so that the first light beam is reflected and diffracted in a predetermined direction and the other light beams are transmitted through the respective light beams incident on the first reflection type diffraction grating 10. Specifically, it is composed of a first dichroic film composed of alternating layers of TiO ₂ and SiO ₂ .

上記第１位相調整層１３は、第１反射型回折格子１０に入射した上記各光ビームのうち該第１反射型回折格子１０を透過する第２光ビームおよび第３光ビームのうち少なくとも第２光ビームの波面の位相を整える（第２反射型回折格子２０に入射する時点での第２光ビームの波面の位相を揃える）ように形成されたものであり（第３光ビームも波面の位相調整を受けるが、第２反射型回折格子２０に入射する時点では波面の位相は揃っていない）、具体的にはＳｉＯ_２の単一層から構成されている。なお、図１では、第１位相調整層１３が第１反射回折層１２の段差部分（凹んだ部分）のみに設けられているが、この段差部分だけではなく、第１反射型回折格子１０と第２反射型回折格子２０との間全体に亘って第１位相調整層１３を設けるようにしてもよい。 The first phase adjustment layer 13 includes at least a second light beam and a third light beam transmitted through the first reflective diffraction grating 10 among the light beams incident on the first reflective diffraction grating 10. The phase of the wavefront of the light beam is adjusted (the phase of the wavefront of the second light beam at the time of incidence on the second reflective diffraction grating 20 is aligned) (the phase of the wavefront of the third light beam is also the same). Although adjusted, the phase of the wave front is not aligned at the time of incidence on the second reflective diffraction grating 20). Specifically, it is composed of a single layer of SiO ₂ . In FIG. 1, the first phase adjustment layer 13 is provided only on the stepped portion (recessed portion) of the first reflective diffraction layer 12, but not only the stepped portion but the first reflective diffraction grating 10 and You may make it provide the 1st phase adjustment layer 13 over the whole between the 2nd reflective diffraction gratings 20. FIG.

上記第２反射型回折格子２０は、上記第１反射型回折格子１０上に形成された第２ベース層２１（上記第１ベース層１１と同様に構成される）を介して、図中左右方向に周期的な凹凸を形成するように設けられた第２反射回折層２２と、該第２反射回折層２２上に形成された第２位相調整層２３とを備えてなる。なお、第２ベース層２１、第２反射回折層２２および第２位相調整層２３は、図中左右方向に周期的な構成を有しており、番号はそれらの一部のみに付している。 The second reflective diffraction grating 20 is arranged in a horizontal direction in the figure through a second base layer 21 (configured in the same manner as the first base layer 11) formed on the first reflective diffraction grating 10. A second reflection diffraction layer 22 provided so as to form periodic irregularities, and a second phase adjustment layer 23 formed on the second reflection diffraction layer 22. In addition, the 2nd base layer 21, the 2nd reflection diffraction layer 22, and the 2nd phase adjustment layer 23 have a periodic structure in the left-right direction in a figure, and the number is attached | subjected only to those parts. .

上記第２反射回折層２２は、第２反射型回折格子２０に入射した上記第２光ビームおよび上記第３光ビームのうち第２光ビームは反射回折せしめ第３光ビームは透過せしめるように形成されたものであり、具体的にはＮｂ_２Ｏ_５とＳｉＯ_２との交互層からなる第２ダイクロイック膜から構成されている。 The second reflection diffraction layer 22 is formed so that the second light beam of the second light beam and the third light beam incident on the second reflection type diffraction grating 20 is reflected and diffracted and the third light beam is transmitted. It is those which are, in particular and a second dichroic film made of alternating layers of Nb ₂ O _5, SiO _2.

上記第２位相調整層２３は、第２反射型回折格子２０に入射した上記２光ビームおよび上記第３光ビームのうち該第２反射型回折格子２０を透過する第３光ビームの波面の位相を整える（第３反射型回折格子３０に入射する時点での第３光ビームの波面の位相を揃える）ように形成されたものであり、具体的にはＳｉＯ_２の単一層から構成されている。なお、図１では、第２位相調整層２３が第２反射回折層１２の段差部分（凹んだ部分）のみに設けられているが、この段差部分だけではなく、第２反射型回折格子２０と第３反射型回折格子３０との間全体に亘って第２位相調整層２３を設けるようにしてもよい。 The second phase adjustment layer 23 includes a phase of a wavefront of a third light beam transmitted through the second reflective diffraction grating 20 out of the two light beams and the third light beam incident on the second reflective diffraction grating 20. (The phase of the wavefront of the third light beam at the time of incidence on the third reflective diffraction grating 30 is made uniform), specifically, it is composed of a single layer of SiO ₂ . . In FIG. 1, the second phase adjustment layer 23 is provided only on the stepped portion (recessed portion) of the second reflective diffraction layer 12, but not only the stepped portion but also the second reflective diffraction grating 20. You may make it provide the 2nd phase adjustment layer 23 over the whole between the 3rd reflective diffraction gratings 30. FIG.

また、上記第３反射型回折格子３０は、上記第２反射型回折格子２０上に形成された第３ベース層３１（第１ベース層１１および第２ベース層２１と同様に構成される）を介して、図中左右方向に周期的な凹凸を形成するように設けられた第３反射回折層３２を備えてなる。なお、第３ベース層３１および第３反射回折層３２は、図中左右方向に周期的な構成を有しており、番号はそれらの一部のみに付している。 The third reflective diffraction grating 30 includes a third base layer 31 (configured in the same manner as the first base layer 11 and the second base layer 21) formed on the second reflective diffraction grating 20. Accordingly, a third reflective diffraction layer 32 is provided so as to form periodic irregularities in the left-right direction in the figure. The third base layer 31 and the third reflective diffraction layer 32 have a periodic configuration in the left-right direction in the figure, and numbers are given to only a part of them.

上記第３反射回折層３２は、第３反射型回折格子３０に入射した上記第３光ビームを所定方向に反射回折せしめるように形成されたものであり、具体的にはＴｉＯ_２とＳｉＯ_２との交互層からなる第３ダイクロイック膜から構成されている。 The third reflective diffractive layer 32 is for the third light beam incident on the third reflecting type diffraction grating 30 is formed so as allowed to reflectively diffracted in a predetermined direction, particularly TiO ₂ and SiO ₂ The third dichroic film is composed of alternating layers.

なお、上述の第１ダイクロイック膜、第２ダイクロイック膜および第３ダイクロイック膜は、いずれも１０から２０層（厚さ１０００〜２０００ｎｍ）程度の多層膜とされている。 Note that each of the first dichroic film, the second dichroic film, and the third dichroic film described above is a multilayer film of about 10 to 20 layers (thickness 1000 to 2000 nm).

ここで、上述の第１ダイクロイック膜、第２ダイクロイック膜および第３ダイクロイック膜の反射特性について図３〜図５を用いて説明する。図３は第１ダイクロイック膜の反射特性を示す図であり、図４は第２ダイクロイック膜の反射特性を示す図であり、図５は第３ダイクロイック膜の反射特性を示す図である。なお、各図の反射特性は入射角度が２３度の場合であり、Ｓ偏光に対する特性が実線で示され、Ｐ偏光に対する特性が１点鎖線で示されている。 Here, the reflection characteristics of the first dichroic film, the second dichroic film, and the third dichroic film will be described with reference to FIGS. 3 is a diagram showing the reflection characteristics of the first dichroic film, FIG. 4 is a diagram showing the reflection characteristics of the second dichroic film, and FIG. 5 is a diagram showing the reflection characteristics of the third dichroic film. In addition, the reflection characteristic of each figure is a case where an incident angle is 23 degree | times, the characteristic with respect to S polarized light is shown as the continuous line, and the characteristic with respect to P polarized light is shown with the dashed-dotted line.

図３に示すように上記第１ダイクロイック膜は、上記第１波長帯域の光は反射せしめ上記第２波長帯域の光および上記第３波長帯域の光は透過せしめる特性を有しており、上記第１光ビームに対する反射率はＳ偏光およびＰ偏光共に１００％に近い高反射率となっている。 As shown in FIG. 3, the first dichroic film has a characteristic of reflecting the light of the first wavelength band and transmitting the light of the second wavelength band and the light of the third wavelength band. The reflectivity for one light beam is a high reflectivity close to 100% for both S-polarized light and P-polarized light.

一方、図４に示すように上記第２ダイクロイック膜は、上記第２波長帯域の光は反射せしめ上記第３波長帯域の光は透過せしめる特性を有しており、上記第２光ビームに対する反射率はＳ偏光およびＰ偏光共に略１００％となっている。 On the other hand, as shown in FIG. 4, the second dichroic film has a characteristic of reflecting the light of the second wavelength band and transmitting the light of the third wavelength band, and has a reflectivity with respect to the second light beam. Is approximately 100% for both S-polarized light and P-polarized light.

また、図５に示すように上記第３ダイクロイック膜は、上記第３波長帯域の光を反射せしめる特性を有しており、上記第３光ビームに対する反射率はＳ偏光およびＰ偏光共に略１００％となっている。 Further, as shown in FIG. 5, the third dichroic film has a characteristic of reflecting the light in the third wavelength band, and the reflectance for the third light beam is approximately 100% for both S-polarized light and P-polarized light. It has become.

このように構成された複数波長用反射型回折格子１は、低コストで作製することが可能であり、かつ第１光ビーム、第２光ビームおよび第３光ビーム毎に所望の回折効率および回折方向を設定することが可能である。 The multi-wavelength reflective diffraction grating 1 configured in this way can be manufactured at low cost, and has a desired diffraction efficiency and diffraction for each of the first light beam, the second light beam, and the third light beam. It is possible to set the direction.

次に、本発明の第２実施形態に係る複数波長用反射型回折格子について説明する。図２は本発明の第２実施形態に係る複数波長用反射型回折格子の概略構成を示す断面図である。 Next, a reflection diffraction grating for multiple wavelengths according to a second embodiment of the present invention will be described. FIG. 2 is a sectional view showing a schematic configuration of a reflection diffraction grating for multiple wavelengths according to a second embodiment of the present invention.

図２に示す第２実施形態の複数波長用反射型回折格子２は、上述の第１光ビーム、第２光ビームおよび第３光ビームが選択的に出力される光路上に配設される３波長対応型のものであり、光学硝材等により形成される透明な基板３Ａ上に、第１反射型回折格子１０Ａ、第１軸位置調整層５、第２反射型回折格子２０Ａ、第２軸位置調整層７および第３反射型回折格子３０Ａが、上記各光ビームの入射側（基板３Ａ側）からこの順に積層されてなる。なお、図１と同様に、周期的な構成を有するものには番号の一部を省略している。 The multiple-wavelength reflective diffraction grating 2 of the second embodiment shown in FIG. 2 is disposed on an optical path through which the first light beam, the second light beam, and the third light beam are selectively output. A wavelength-corresponding type, on a transparent substrate 3A formed of an optical glass material or the like, a first reflective diffraction grating 10A, a first axis position adjusting layer 5, a second reflective diffraction grating 20A, a second axis position The adjustment layer 7 and the third reflective diffraction grating 30A are laminated in this order from the light incident side (substrate 3A side). As in FIG. 1, some of the numbers are omitted for those having a periodic configuration.

上記第１反射型回折格子１０Ａは、上記基板３Ａ上に形成された第１ベース層１１Ａ（上記第１ベース層１１と同様に構成される）を介して、図中左右方向に周期的な凹凸を形成するように設けられた第１反射回折層１２Ａと、該第１反射回折層１２Ａ上に形成された第１位相調整層１３Ａとを備えてなる。なお、図２では、第１位相調整層１３Ａが第１反射回折層１２Ａの段差部分（凹んだ部分）のみに設けられているが、この段差部分だけではなく、第１反射型回折格子１０Ａと後述する第１軸位置調整層５との間全体に亘って第１位相調整層１３Ａを設けるようにしてもよい。 The first reflective diffraction grating 10A has periodic irregularities in the horizontal direction in the figure via a first base layer 11A (configured in the same manner as the first base layer 11) formed on the substrate 3A. And a first phase adjustment layer 13A formed on the first reflection diffraction layer 12A. In FIG. 2, the first phase adjustment layer 13A is provided only on the stepped portion (the recessed portion) of the first reflective diffraction layer 12A, but not only the stepped portion and the first reflective diffraction grating 10A. The first phase adjustment layer 13 </ b> A may be provided over the entire area between the first axis position adjustment layer 5 described later.

上記第１反射回折層１２Ａは、第１反射型回折格子１０Ａに入射した上記各光ビームのうち第１光ビームは所定方向に反射回折せしめ他の光ビームは透過せしめるように形成されたものであり、具体的にはＴｉＯ_２とＳｉＯ_２との交互層からなる上記第１ダイクロイック膜から構成されている。 The first reflective diffraction layer 12A is formed so that the first light beam is reflected and diffracted in a predetermined direction and the other light beams are transmitted through the respective light beams incident on the first reflective diffraction grating 10A. Specifically, the first dichroic film is composed of alternating layers of TiO ₂ and SiO ₂ .

上記第１位相調整層１３Ａは、第１反射型回折格子１０Ａに入射した上記各光ビームのうち該第１反射型回折格子１０Ａを透過する第２光ビームの波面の位相を整える（第１軸位置調整層５に入射する時点での第２光ビームの波面の位相を揃える）ように形成されたものであり、具体的にはＳｉＯ_２の単一層から構成されている。 The first phase adjustment layer 13A adjusts the phase of the wavefront of the second light beam that passes through the first reflective diffraction grating 10A among the light beams incident on the first reflective diffraction grating 10A (first axis). The phase of the wavefront of the second light beam at the time of entering the position adjusting layer 5 is made uniform, and specifically, it is composed of a single layer of SiO ₂ .

上記第２反射型回折格子２０Ａは、第１反射型回折格子１０上に形成された第２ベース層２１Ａ（上記第２ベース層２１と同様に構成される）を介して、図中左右方向に周期的な凹凸を形成するように設けられた第２反射回折層２２Ａと、該第２反射回折層２２Ａ上に形成された第２位相調整層２３Ａとを備えてなる。なお、図２では、第２位相調整層２３Ａが第２反射回折層２２Ａの段差部分（凹んだ部分）のみに設けられているが、この段差部分だけではなく、第２反射型回折格子２０Ａと後述する第２軸位置調整層７との間全体に亘って第２位相調整層２３Ａを設けるようにしてもよい。 The second reflective diffraction grating 20A is arranged in the left-right direction in the figure via a second base layer 21A (configured in the same manner as the second base layer 21) formed on the first reflective diffraction grating 10. A second reflection diffraction layer 22A provided so as to form periodic unevenness and a second phase adjustment layer 23A formed on the second reflection diffraction layer 22A are provided. In FIG. 2, the second phase adjustment layer 23A is provided only on the stepped portion (recessed portion) of the second reflective diffraction layer 22A, but not only the stepped portion but the second reflective diffraction grating 20A. You may make it provide the 2nd phase adjustment layer 23A over the whole between the 2nd axis position adjustment layers 7 mentioned later.

上記第２反射回折層２２Ａは、第２反射型回折格子２０Ａに入射した上記第２光ビームおよび上記第３光ビームのうち第２光ビームは反射回折せしめ第３光ビームは透過せしめるように形成されたものであり、具体的にはＮｂ_２Ｏ_５とＳｉＯ_２との交互層からなる上記第２ダイクロイック膜から構成されている。 The second reflective diffraction layer 22A is formed so that the second light beam of the second light beam and the third light beam incident on the second reflective diffraction grating 20A is reflected and diffracted and the third light beam is transmitted. It is those which are, specifically, is configured from the second dichroic film made of alternating layers of Nb ₂ O _5, SiO _2.

上記第２位相調整層２３Ａは、第２反射型回折格子２０Ａに入射した上記第２光ビームおよび上記第３光ビームのうち該第２反射型回折格子２０Ａを透過する第３光ビームの波面の位相を整える（第２軸位置調整層７に入射する時点での第３光ビームの波面の位相を揃える）ように形成されたものであり、具体的にはＳｉＯ_２の単一層から構成されている。 The second phase adjusting layer 23A has a wavefront of a third light beam transmitted through the second reflective diffraction grating 20A out of the second light beam and the third light beam incident on the second reflective diffraction grating 20A. It is formed so as to adjust the phase (align the phase of the wavefront of the third light beam at the time of incidence on the second axis position adjusting layer 7), and is specifically composed of a single layer of SiO ₂ Yes.

また、この第２実施形態の特徴として複数波長用反射型回折格子２は、第１反射型回折格子１０Ａと第２反射型回折格子２０Ａとの間に第１軸位置調整層５を備え、第２反射型回折格子２０Ａと第３反射型回折格子３０Ａとの間に第２軸位置調整層７を備えている。 Further, as a feature of the second embodiment, the multi-wavelength reflection type diffraction grating 2 includes a first axial position adjustment layer 5 between the first reflection type diffraction grating 10A and the second reflection type diffraction grating 20A. A second axis position adjusting layer 7 is provided between the two-reflection diffraction grating 20A and the third reflection-type diffraction grating 30A.

これら第１軸位置調整層５および第２軸位置調整層７は、複数波長用反射型回折格子２に選択的に入射される第１光ビーム、第２光ビームおよび第３光ビームの入射時の軸の位置が互いに異なる（入射角度は互いに一致する）場合に有用なもので、次のような機能を有している。 The first axis position adjustment layer 5 and the second axis position adjustment layer 7 are formed when the first light beam, the second light beam, and the third light beam are selectively incident on the reflection diffraction grating 2 for multiple wavelengths. This is useful when the positions of the axes are different (incident angles coincide with each other), and has the following functions.

すなわち、第１軸位置調整層５は、第２反射回折層２２Ａにより反射回折せしめられた第２光ビームの０次回折光の出射時の軸の位置を、第１反射回折層１２Ａにより反射回折せしめられた第１光ビームの０次回折光の軸の位置に一致させ、第２軸位置調整層７は、第３反射回折層３２Ａにより反射回折せしめられた第３光ビームの０次回折光の軸の位置を、第２反射回折層２２Ａにより反射回折せしめられた第２光ビームの０次回折光の軸の位置に一致させる機能をそれぞれ有している。 That is, the first axis position adjusting layer 5 causes the first reflection diffraction layer 12A to reflect and diffract the axis position when the second-order light beam reflected and diffracted by the second reflection diffraction layer 22A is emitted. The second axis position adjusting layer 7 is made to coincide with the position of the axis of the zeroth-order diffracted light of the first light beam, and the axis of the zeroth-order diffracted light of the third light beam reflected and diffracted by the third reflection diffraction layer 32A Each has a function of making the position coincide with the position of the axis of the 0th-order diffracted light of the second light beam reflected and diffracted by the second reflective diffraction layer 22A.

これにより、第２実施形態に係る複数波長用反射型回折格子２においては、選択的に入射される第１光ビーム、第２光ビームおよび第３光ビームの入射時の軸の位置が互いに異なる場合でも、反射回折せしめた時点では各光ビームの０次回折光の軸の位置を互いに一致させることが可能となる。 Thereby, in the reflective diffraction grating 2 for multiple wavelengths according to the second embodiment, the positions of the axes at the time of incidence of the first light beam, the second light beam, and the third light beam that are selectively incident are different from each other. Even in this case, it is possible to make the positions of the axes of the 0th-order diffracted light beams of the respective light beams coincide with each other at the time of reflection diffraction.

なお、上述の第１軸位置調整層５および第２軸位置調整層７は、上記基板３Ａ（３）と同様の光学硝材等からなる厚さ０．１ｍｍ程度の薄板により構成することができるが、これらをＳｉＯ_２の単一層により構成することも可能である。ＳｉＯ_２の単一層により構成する場合には、第１軸位置調整層５を上記第１位相調整層１３Ａと一体に構成し、第２軸位置調整層７を上記第２位相調整層２３Ａと一体に構成することも可能である。 The first axis position adjusting layer 5 and the second axis position adjusting layer 7 described above can be formed of a thin plate having a thickness of about 0.1 mm made of an optical glass material similar to the substrate 3A (3). These can also be constituted by a single layer of SiO ₂ . In the case of a single layer of SiO ₂ , the first axial position adjusting layer 5 is configured integrally with the first phase adjusting layer 13A, and the second axial position adjusting layer 7 is integrated with the second phase adjusting layer 23A. It is also possible to configure.

次に、本発明に係る光ピックアップ装置の実施形態について説明する。図７は本発明の一実施形態に係る光ピックアップ装置の概略構成図である。 Next, an embodiment of an optical pickup device according to the present invention will be described. FIG. 7 is a schematic configuration diagram of an optical pickup device according to an embodiment of the present invention.

図７に示す光ピックアップ装置５０は、上記第１光ビーム用の光記録媒体Ｄ_１（ＢＤ）、上記第２光ビーム用の光記録媒体Ｄ_２（ＤＶＤ）および上記第３光ビーム用の光記録媒体Ｄ_３（ＣＤ）のデータ再生を行うものであり、上述の複数波長用反射型回折格子２を用いることにより、上記各光ビームに対応させた３ビーム法による信号読取りおよびトラッキング制御を行うように構成されている。 The optical pickup device 50 shown in FIG. 7 includes an optical recording medium D ₁ (BD) for the first light beam, an optical recording medium D ₂ (DVD) for the second light beam, and light for the third light beam. Data reproduction of the recording medium D ₃ (CD) is performed, and by using the above-described reflection diffraction grating 2 for plural wavelengths, signal reading and tracking control are performed by the three-beam method corresponding to each light beam. It is configured as follows.

この光ピックアップ装置５０は、３波長レーザ光源５１と、該３波長レーザ光源５１からの各光ビームの光路上に配された第１プリズム５２と、該第１プリズム５２と接合された第２プリズム５３と、コリメータ５５ａや対物レンズ５５ｂ等からなるピックアップレンズ系５５と、３波長用ホログラム素子５６と、信号読取りおよびトラッキング制御用の３波長用受光装置５７と、３波長レーザ光源５１からの出力を制御するためのＡＰＣ用受光装置５８とを備えてなる。 The optical pickup device 50 includes a three-wavelength laser light source 51, a first prism 52 disposed on the optical path of each light beam from the three-wavelength laser light source 51, and a second prism joined to the first prism 52. 53, a pickup lens system 55 including a collimator 55a and an objective lens 55b, a three-wavelength hologram element 56, a three-wavelength light receiving device 57 for signal reading and tracking control, and outputs from the three-wavelength laser light source 51. And an APC light-receiving device 58 for control.

上記３波長レーザ光源５１は、上述の第１光ビーム、第２光ビームおよび第３光ビームを、図中上方に向けて選択的に出力し得るように構成されている。この３波長レーザ光源５１から出力される各光ビームの軸は互いに平行となるが、各光ビームの発光点の位置が互いに異なっているため、各光ビームの軸の位置は図中左右方向に少しずつ（例えば０．１ｍｍ程度）ずれている。 The three-wavelength laser light source 51 is configured to selectively output the above-described first light beam, second light beam, and third light beam upward in the drawing. Although the axes of the light beams output from the three-wavelength laser light source 51 are parallel to each other, the positions of the light emission points of the light beams are different from each other. It is shifted little by little (for example, about 0.1 mm).

上記第１プリズム５２と上記第２プリズム５３との接合面５４にはビームスプリッタ膜（以下「ＢＳ膜」と略称する）が設けられている。また、この接合面と平行に配された、上記第１プリズム５２の第２面５２ｂには、上述の複数波長用反射型回折格子２が設置されている。なお、この第１プリズム５２の第２面５２ｂは、上記３波長レーザ光源５１から選択的に出力された各光ビームの該第２面５２ｂへの入射角度（上記複数波長用反射型回折格子２への入射角度も同じとなる）が所定の角度（例えば２３°）となるように設定されている。 A beam splitter film (hereinafter abbreviated as “BS film”) is provided on the joint surface 54 between the first prism 52 and the second prism 53. Further, the above-described reflection diffraction grating 2 for a plurality of wavelengths is installed on the second surface 52b of the first prism 52 arranged in parallel with the joint surface. The second surface 52b of the first prism 52 has an incident angle of each light beam selectively output from the three-wavelength laser light source 51 to the second surface 52b (the reflection diffraction grating 2 for multiple wavelengths). Is set to be a predetermined angle (for example, 23 °).

ここで、上記ＢＳ膜の反射特性について図６を用いて説明する。図６はＢＳ膜の反射特性を示す図である。なお、図６の反射特性は入射角度が２３度の場合であり、Ｓ偏光に対する特性が実線で示され、Ｐ偏光に対する特性が１点鎖線で示されている。 Here, the reflection characteristic of the BS film will be described with reference to FIG. FIG. 6 is a diagram showing the reflection characteristics of the BS film. The reflection characteristics in FIG. 6 are for an incident angle of 23 degrees, the characteristics for S-polarized light are indicated by a solid line, and the characteristics for P-polarized light are indicated by a one-dot chain line.

図６に示すように上記ＢＳ膜は、上述の第１光ビーム、第２光ビームおよび第３光ビームにそれぞれ対応する波長の光については、いずれもその大部分を反射せしめ、その余の部分を透過せしめるように構成されている。 As shown in FIG. 6, the BS film reflects most of the wavelengths of light corresponding to the first light beam, the second light beam, and the third light beam, respectively, and the remaining portion. It is comprised so that it may permeate | transmit.

以下、この光ピックアップ装置５０の作用について図７を用いて説明する。
光記録媒体Ｄ_１の再生を行う場合には、３波長レーザ光源５１から第１光ビームが出力される。この出力された第１光ビームは、第１プリズム５２の第１面５２ａから該第１プリズム５２内に入射し、第２面５２ｂに設置された複数波長用反射型回折格子２に入射する。 Hereinafter, the operation of the optical pickup device 50 will be described with reference to FIG.
When reproducing the optical recording medium D ₁ , the first light beam is output from the three-wavelength laser light source 51. The output first light beam is incident on the first prism 52 from the first surface 52a of the first prism 52, and is incident on the reflection diffraction grating 2 for multiple wavelengths provided on the second surface 52b.

複数波長用反射型回折格子２に入射した第１光ビームは、基板３Ａを透過して第１反射型回折格子１０Ａに入射し、第１反射回折層１２Ａにおいて反射回折せしめられ（図２参照）、０次回折光からなるメインビームと±１次回折光からなる２つのサブビームの３ビームに分岐されて（図７において３ビームの図示は省略している）、該複数波長用反射型回折格子２から出射される。 The first light beam incident on the multi-wavelength reflective diffraction grating 2 passes through the substrate 3A and enters the first reflective diffraction grating 10A, and is reflected and diffracted by the first reflective diffraction layer 12A (see FIG. 2). The beam is branched into three beams of a main beam composed of 0th order diffracted light and two sub beams composed of ± 1st order diffracted light (illustration of 3 beams is omitted in FIG. 7). Emitted.

複数波長用反射型回折格子２から出射された第１光ビームは上記接合面５４に入射し、上記ＢＳ膜においてその大部分が図中上方に反射され、その余の部分がＢＳ膜を透過して第２プリズム５３内に入射する。第２プリズム５３内に入射した第１光ビームは、第２プリズム５３の第１面５３ａで全反射され、第２面５３ｂから出射されて上記ＡＰＣ用受光装置５８内に入射する。入射された第１光ビームの光量が、ＡＰＣ用受光装置５８により検出され、その検出光量に基づき、３波長レーザ光源５１からの第１光ビームの出力が自動調整されるようになっている。 The first light beam emitted from the reflective diffraction grating 2 for multiple wavelengths is incident on the bonding surface 54, most of the BS film is reflected upward in the figure, and the remaining part is transmitted through the BS film. Then, the light enters the second prism 53. The first light beam incident on the second prism 53 is totally reflected by the first surface 53a of the second prism 53, is emitted from the second surface 53b, and enters the APC light receiving device 58. The light amount of the incident first light beam is detected by the APC light receiving device 58, and the output of the first light beam from the three-wavelength laser light source 51 is automatically adjusted based on the detected light amount.

一方、接合面５４のＢＳ膜から図中上方に反射された第１光ビームは、第１プリズム５２の第３面５２ｃから出射され、ピックアップレンズ系５５を介して光記録媒体Ｄ_１のデータ記録面に３ビーム状態で集光照射される。照射された第１光ビームは光記録媒体Ｄ_１のデータ記録面において反射され、この際にデータ情報を担持されて、概ね元の光路を辿り第２プリズム５３内に再び入射する。 Meanwhile, the first light beam from the BS film bonding surface 54 is reflected upward in the drawing is emitted from the third surface 52c of the first prism 52, via a pickup lens system 55 of the data recording the optical recording medium D ₁ The surface is condensed and irradiated in a 3-beam state. The irradiated first light beam is reflected on the data recording surface of the optical recording medium D ₁ , and at this time, the data information is carried and substantially retraces the original optical path and enters the second prism 53 again.

第２プリズム５３内に再び入射した第１光ビームの一部は、接合面５４のＢＳ膜を透過して第２プリズム５３の第１面５３ａから図中下方に向けて出射される。この出射された第１光ビームは、３波長用ホログラム素子５６において図中左方に反射され、３波長用受光装置５７に３ビーム状態で入射する。 A part of the first light beam that has entered the second prism 53 again passes through the BS film on the bonding surface 54 and is emitted downward from the first surface 53a of the second prism 53 in the drawing. The emitted first light beam is reflected leftward in the drawing by the three-wavelength hologram element 56 and enters the three-wavelength light receiving device 57 in a three-beam state.

３波長用受光装置５７は、メインビーム検出用の検出部と２つのサブビーム検出用の検出部とを備えており、メインビームの検出に基づき光記録媒体Ｄ_１のデータの再生が行われ、サブビームの検出に基づき光記録媒体Ｄ_１のトラッキング制御が行われるようになっている。 The three-wavelength light receiving device 57 includes a detection unit for main beam detection and two detection units for sub-beam detection. Based on the detection of the main beam, data reproduction of the optical recording medium D ₁ is performed. tracking control based optical recording medium D ₁ in the detection and the like are performed in.

一方、光記録媒体Ｄ_２の再生を行う場合には、３波長レーザ光源５１から第２光ビームが出力される。この出力された第２光ビームは、第１プリズム５２の第１面５２ａから該第１プリズム５２内に入射し、第２面５２ｂに設置された複数波長用反射型回折格子２に入射する。 On the other hand, when reproducing the optical recording medium D ₂ , the second light beam is output from the three-wavelength laser light source 51. The output second light beam enters the first prism 52 from the first surface 52a of the first prism 52, and enters the reflection diffraction grating 2 for multiple wavelengths provided on the second surface 52b.

複数波長用反射型回折格子２に入射した第２光ビームは、基板３Ａ、第１反射型回折格子１０Ａおよび第１軸位置調整層５を透過して第２反射型回折格子２０Ａに入射し、第２反射回折層２２Ａにおいて反射回折せしめられ（図２参照）、０次回折光からなるメインビームと±１次回折光からなる２つのサブビームの３ビームに分岐されて、該複数波長用反射型回折格子２から出射される。なお、第２反射回折層２２Ａにおいて反射回折せしめられた第２光ビームの０次回折光の軸の位置は、上述の光記録媒体Ｄ_１の再生を行う場合における、第１反射型回折格子１０Ａの第１反射回折層１２Ａにおいて反射回折せしめられた第１光ビームの０次回折光の軸の位置と一致するようになっている。 The second light beam incident on the multi-wavelength reflective diffraction grating 2 is transmitted through the substrate 3A, the first reflective diffraction grating 10A, and the first axis position adjusting layer 5, and is incident on the second reflective diffraction grating 20A. Reflected and diffracted by the second reflective diffraction layer 22A (see FIG. 2), the multi-wavelength reflective diffraction grating is branched into three beams of a main beam composed of zero-order diffracted light and two sub beams composed of ± first-order diffracted light. 2 is emitted. Incidentally, 0 position of the axis of the diffracted light of the second light beam that is allowed reflected and diffracted at the second reflective diffractive layer 22A is in case of reproducing the above-described optical recording medium D _1, the first reflection type diffraction grating 10A The position of the axis of the 0th-order diffracted light of the first light beam reflected and diffracted by the first reflective diffraction layer 12A coincides.

また、光記録媒体Ｄ_３の再生を行う場合には、３波長レーザ光源５１から第３光ビームが出力される。この出力された第３光ビームは、第１プリズム５２の第１面５２ａから該第１プリズム５２内に入射し、第２面５２ｂに設置された複数波長用反射型回折格子２に入射する。 When reproducing the optical recording medium D ₃ , the third light beam is output from the three-wavelength laser light source 51. The output third light beam enters the first prism 52 from the first surface 52a of the first prism 52, and enters the multiple-wavelength reflective diffraction grating 2 installed on the second surface 52b.

複数波長用反射型回折格子２に入射した第３光ビームは、基板３Ａ、第１反射型回折格子１０Ａ、第１軸位置調整層５、第２反射型回折格子２０Ａおよび第２軸位置調整層７を透過して第３反射型回折格子３０Ａに入射し、第３反射回折層３２Ａにおいて反射回折せしめられ（図２参照）、０次回折光からなるメインビームと±１次回折光からなる２つのサブビームの３ビームに分岐されて、該複数波長用反射型回折格子２から出射される。なお、第３反射回折層３２Ａにおいて反射回折せしめられた第３光ビームの０次回折光の軸の位置は、上述の光記録媒体Ｄ_２の再生を行う場合における、第２反射型回折格子２０Ａの第２反射回折層２２Ａにおいて反射回折せしめられた第２光ビームの０次回折光の軸の位置と一致するようになっている。 The third light beam incident on the reflection diffraction grating for multiple wavelengths 2 is the substrate 3A, the first reflection diffraction grating 10A, the first axis position adjustment layer 5, the second reflection type diffraction grating 20A, and the second axis position adjustment layer. 7, enters the third reflective diffraction grating 30A, is reflected and diffracted by the third reflective diffraction layer 32A (see FIG. 2), and has two main beams consisting of a 0th-order diffracted light and a ± 1st-order diffracted light. Are emitted from the reflection diffraction grating 2 for multiple wavelengths. Incidentally, 0 position of the axis of the diffracted light of the third light beam that is allowed reflected and diffracted in the third reflective diffractive layer 32A is in case of reproducing the above-described optical recording medium D _2, the second reflection type diffraction grating 20A The position of the axis of the 0th-order diffracted light beam of the second light beam reflected and diffracted by the second reflective diffraction layer 22A coincides.

複数波長用反射型回折格子２から出射された後の第２光ビームおよび第３光ビームの作用は、第１光ビームの場合と同様である。なお、上記３波長用受光装置５７は、第１光ビーム用の検出部（メインビーム用および２つのサブビーム用。以下同じ）と第２光ビーム用の検出部の検出部と第３光ビーム用の検出部とを別個に備えている。また、上記３波長用ホログラム素子５６は、３波長用受光装置５７に向かう各光ビームが、それぞれに対応した各検出部に入射するように、各光ビームの反射角度を調整し得るように構成されている。 The operations of the second light beam and the third light beam after being emitted from the multi-wavelength reflective diffraction grating 2 are the same as in the case of the first light beam. The three-wavelength light receiving device 57 includes a first light beam detector (for the main beam and two sub beams; the same applies hereinafter), a detector of the second light beam detector, and a third light beam. Are separately provided. The three-wavelength hologram element 56 is configured so that the reflection angle of each light beam can be adjusted so that each light beam directed to the three-wavelength light receiving device 57 is incident on each corresponding detection unit. Has been.

なお、この光ピックアップ装置５０において、波長レーザ光源５１から出力され複数波長用反射型回折格子２を介して第１プリズム５２に入射する第１乃至第３光ビームがＳ偏光となるように構成するとともに、光記録媒体Ｄ_１，Ｄ_２，Ｄ_３からピックアップレンズ系５５を介して第２プリズム５３に戻る第１乃至第３光ビームがＰ偏光となるように構成することができる（例えば、第２プリズム５３と光記録媒体Ｄ_１，Ｄ_２，Ｄ_３との間の光路上に１／４波長板を配置する）。この場合、図６に示すようにＢＳ膜が、Ｐ偏光よりもＳ偏光の方が１０％程度高い反射特性を有していることで、光記録媒体Ｄ_１，Ｄ_２，Ｄ_３からのＰ偏光からなる戻り光を、Ｓ偏光からなる場合に比べてより多くＢＳ膜を透過させることができるので、信号読取りおよびトラッキング制御に用いる光の利用効率を高めることが可能となる。 The optical pickup device 50 is configured such that the first to third light beams output from the wavelength laser light source 51 and incident on the first prism 52 via the multi-wavelength reflective diffraction grating 2 are S-polarized light. In addition, the first to third light beams that return from the optical recording media D ₁ , D ₂ , D ₃ to the second prism 53 via the pickup lens system 55 can be configured to be P-polarized light (for example, the first 2) A quarter-wave plate is disposed on the optical path between the prism 53 and the optical recording media D ₁ , D ₂ , D ₃ . In this case, as shown in FIG. 6, the BS film has a reflection characteristic that the S-polarized light is about 10% higher than the P-polarized light, so that P from the optical recording media D ₁ , D ₂ , D ₃ can be obtained. Since the return light composed of polarized light can be transmitted through the BS film more than in the case of composed of S-polarized light, it is possible to increase the utilization efficiency of light used for signal reading and tracking control.

以上、本発明の実施形態について説明したが、本発明は上記実施形態に態様が限定されるものではなく、種々に態様を変更することができる。 As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, Aspects can be variously changed.

例えば、上述の複数波長用反射型回折格子１，２は３波長用のものであるが、本発明は２波長用のものや４波長以上のより多波長用のものとして構成することも可能である。 For example, although the above-mentioned reflection diffraction gratings 1 and 2 for multiple wavelengths are for three wavelengths, the present invention can be configured for two wavelengths or for more than four wavelengths. is there.

また、上記実施形態において例示した波長以外の各光ビームに対応するように構成することも可能であり、その際の膜構成についても適宜変更することが可能である。 Further, it is possible to configure so as to correspond to each light beam other than the wavelength exemplified in the above embodiment, and it is possible to appropriately change the film configuration at that time.

また、上記実施形態においては、第３反射回折層２２，２２Ａが第３ダイクロイック膜から構成されているが、これを全反射膜で構成することも可能である。 Moreover, in the said embodiment, although the 3rd reflection diffraction layers 22 and 22A are comprised from the 3rd dichroic film | membrane, this can also be comprised by a total reflection film.

また、上記実施形態においては、光ピックアップ装置５０をデータ再生用のものとしているが、本発明はデータ記録用やデータの記録および再生を共に行う光ピックアップ装置にも適用することができる。 In the above embodiment, the optical pickup device 50 is used for data reproduction. However, the present invention can also be applied to an optical pickup device that performs data recording and both data recording and reproduction.

また、本発明に係る複数波長用反射型回折格子は、光ピックアップ装置以外の光学機器等に適用することも可能である。 Further, the reflection diffraction grating for multiple wavelengths according to the present invention can be applied to an optical apparatus other than the optical pickup device.

第１実施形態に係る複数波長用反射型回折格子の概略構成を示す断面図Sectional drawing which shows schematic structure of the reflection type diffraction grating for multiple wavelengths which concerns on 1st Embodiment 第２実施形態に係る複数波長用反射型回折格子の概略構成を示す断面図Sectional drawing which shows schematic structure of the reflection type diffraction grating for multiple wavelengths which concerns on 2nd Embodiment 第１ダイクロイック膜の反射特性を示す図The figure which shows the reflective characteristic of a 1st dichroic film | membrane 第２ダイクロイック膜の反射特性を示す図The figure which shows the reflective characteristic of a 2nd dichroic film | membrane 第３ダイクロイック膜の反射特性を示す図The figure which shows the reflective characteristic of a 3rd dichroic film | membrane ＢＳ膜の反射特性を示す図The figure which shows the reflective characteristic of BS film 一実施形態に係る光ピックアップ装置の概略構成図1 is a schematic configuration diagram of an optical pickup device according to an embodiment.

Explanation of symbols

１複数波長用反射型回折格子（第１実施形態）
２複数波長用反射型回折格子（第２実施形態）
３，３Ａ基板
５第１軸位置調整層
７第２軸位置調整層
１０，１０Ａ第１反射型回折格子
１１，１１Ａ第１ベース層
１２，１２Ａ第１反射回折層
１３，１３Ａ第１位相調整層
２０，２０Ａ第２反射型回折格子
２１，２１Ａ第２ベース層
２２，２２Ａ第２反射回折層
２３，２３Ａ第２位相調整層
３０，３０Ａ第３反射型回折格子
３１，３１Ａ第３ベース層
３２，３２Ａ第３反射回折層
５１３波長レーザ光源
５２第１プリズム
５２ａ（第１プリズムの）第１面
５２ｂ（第１プリズムの）第２面
５２ｃ（第１プリズムの）第３面
５３第２プリズム
５３ａ（第２プリズムの）第１面
５３ｂ（第２プリズムの）第２面
５４接合面
５５ピックアップレンズ系
５５ａコリメータ
５５ｂ対物レンズ
５６３波長用ホログラム素子
５７３波長用受光装置
５８ＡＰＣ用受光装置
1 Reflective diffraction grating for multiple wavelengths (first embodiment)
2 Reflective diffraction grating for multiple wavelengths (second embodiment)
3, 3A Substrate 5 First axis position adjustment layer 7 Second axis position adjustment layer 10, 10A First reflective diffraction grating 11, 11A First base layer 12, 12A First reflection diffraction layer 13, 13A First phase adjustment layer 20, 20A Second reflection type diffraction grating 21, 21A Second base layer 22, 22A Second reflection diffraction layer 23, 23A Second phase adjustment layer 30, 30A Third reflection type diffraction grating 31, 31A Third base layer 32, 32A Third reflective diffraction layer 51 Three-wavelength laser light source 52 First prism 52a First surface 52b (first prism) Second surface 52c (first prism) third surface 53 Second prism 53a First surface 53b (of the second prism) Second surface (of the second prism) 54 Joint surface 55 Pickup lens system 55a Collimator 55b Objective lens 56 Three-wavelength hologram Child 57 3-wavelength light-receiving unit 58 APC light-receiving device

Claims

1st to N-th N light beams (N is an integer of 2 or more), which belong to different wavelength bands, are arranged on the optical path where the 1st to N-th light beams are selectively output. A reflection diffraction grating for multiple wavelengths,
N reflective diffraction gratings from 1 to N are stacked in this order from the incident side of the N light beams,
The jth reflection type diffraction grating (j is an arbitrary integer from 1 to N-1) is the jth light beam out of the jth light beam to the Nth light beam incident on the jth reflection type diffraction grating. A j-th reflection diffractive layer for reflecting and diffracting other light beams;
The Nth reflection type diffraction grating has an Nth reflection diffraction layer for reflecting and diffracting the Nth light beam incident on the Nth reflection type diffraction grating,
The jth reflection type diffraction grating adjusts the phase of the wavefront of at least the (j + 1) th light beam from the (j + 1) th light beam to the Nth light beam transmitted through the jth reflection type diffraction grating. A reflective diffraction grating for multiple wavelengths, comprising a phase adjustment layer.

The j-th reflection diffraction layer reflects the j-th wavelength band light from the j-th wavelength band light to the N-th wavelength band light and transmits the other wavelength band light through the j-th dichroic film. Are arranged in a periodic uneven shape,
The Nth reflective diffractive layer is formed by periodically disposing an Nth dichroic film or a total reflection film having a characteristic of reflecting light in the Nth wavelength band. The reflective diffraction grating for multiple wavelengths according to claim 1.

The position of the axis of the 0th-order diffracted light beam of the (j + 1) th light beam reflected and diffracted by the (j + 1) th reflective diffraction layer between the jth reflective diffraction grating and the (j + 1) th reflective diffraction grating, 3. The j-th axis position adjustment layer is provided to match the position of the 0th-order diffracted light axis of the j-th light beam reflected and diffracted by the j-th reflection diffraction layer. The reflective diffraction grating for multiple wavelengths as described.

A first light beam belonging to the first wavelength band, a second light beam belonging to a second wavelength band different from the first wavelength band, and a third wavelength band different from the first wavelength band and the second wavelength band The third light beam belonging to is a reflection diffraction grating for a plurality of wavelengths disposed on an optical path selectively output,
A first reflective diffraction grating, a second reflective diffraction grating, and a third reflective diffraction grating are stacked in this order from the incident side of the first light beam, the second light beam, and the third light beam,
The first reflection type diffraction grating reflects and diffracts the first light beam among the first light beam to the third light beam incident on the first reflection type diffraction grating and transmits the other light beam. A reflection diffraction layer, and a first phase adjustment layer for adjusting a phase of a wave front of at least the second light beam of the transmitted second light beam and the third light beam,
The second reflection type diffraction grating reflects and diffracts the second light beam of the second light beam and the third light beam incident on the second reflection type diffraction grating and transmits the third light beam. A second reflection diffraction layer and a second phase adjustment layer for adjusting the phase of the wavefront of the transmitted third light beam,
The third reflective diffraction grating has a third reflective diffraction layer that reflects and diffracts the third light beam incident on the third reflective diffraction grating,
The first reflective diffractive layer has a periodic concavo-convex shape on a first dichroic film having a characteristic of reflecting light in the first wavelength band and transmitting light in the second wavelength band and light in the third wavelength band. It is arranged in the
The second reflection diffraction layer is formed by arranging a second dichroic film having a characteristic of reflecting the light of the second wavelength band and transmitting the light of the third wavelength band in a periodic uneven shape. Yes,
The third reflective diffractive layer is formed by arranging a third dichroic film or a total reflection film having a characteristic of reflecting the light in the third wavelength band in a periodic uneven shape. Reflective diffraction grating for multiple wavelengths.

The position of the axis of the 0th-order diffracted light beam of the second light beam reflected and diffracted by the second reflective diffraction layer between the first reflective diffraction grating and the second reflective diffraction grating is defined as the first reflective diffraction grating. A first axis position adjusting layer is provided to match the position of the axis of the 0th-order diffracted light of the first light beam reflected and diffracted by the reflection diffraction layer;
The position of the axis of the 0th-order diffracted light beam of the third light beam reflected and diffracted by the third reflective diffraction layer between the second reflective diffraction grating and the third reflective diffraction grating is defined as the second reflective diffraction grating. 5. The multi-wavelength reflection layer according to claim 4, further comprising a second-axis position adjusting layer that matches an axis position of the zero-order diffracted light of the second light beam reflected and diffracted by the reflection diffraction layer. Type diffraction grating.

An optical pickup device comprising the reflection diffraction grating for multiple wavelengths according to any one of claims 1 to 5.