JPH0650717A - Focal point error detector - Google Patents
Focal point error detectorInfo
- Publication number
- JPH0650717A JPH0650717A JP20407792A JP20407792A JPH0650717A JP H0650717 A JPH0650717 A JP H0650717A JP 20407792 A JP20407792 A JP 20407792A JP 20407792 A JP20407792 A JP 20407792A JP H0650717 A JPH0650717 A JP H0650717A
- Authority
- JP
- Japan
- Prior art keywords
- diffraction grating
- light
- focus error
- reflected light
- error detector
- 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.)
- Withdrawn
Links
Landscapes
- Length Measuring Devices By Optical Means (AREA)
- Measurement Of Optical Distance (AREA)
- Diffracting Gratings Or Hologram Optical Elements (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は焦点誤差検出装置に関
し、特に、光源からの光を光学系で測定対象物に導き、
その反射光を受光することによって焦点の誤差を検出す
る検査装置や測定器のような焦点誤差検出装置に関す
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a focus error detecting device, and more particularly, to guiding light from a light source to an object to be measured by an optical system,
The present invention relates to a focus error detection device such as an inspection device or a measuring device that detects a focus error by receiving the reflected light.
【０００２】[0002]
【従来の技術】図５は屈折型光学素子（ガラス製レン
ズ）を用いた非点収差法による従来の焦点誤差検出装置
の一例を示す図である。図５において、レーザ発振器１
から照射されたビームは偏光ビームスプリッタ２によっ
て方向が変えられ、１／４波長板３に入射される。１／
４波長板３によって垂直偏波から円偏波に変換されたビ
ームは対物レンズ４によって測定対象物であるミラー５
に集光される。集光されたビームはミラー５によって円
偏波の回転方向が入射時の逆回転となって反射される。2. Description of the Related Art FIG. 5 is a diagram showing an example of a conventional focus error detection apparatus by an astigmatism method using a refraction type optical element (glass lens). In FIG. 5, the laser oscillator 1
The direction of the beam emitted from is changed by the polarization beam splitter 2 and is incident on the quarter-wave plate 3. 1 /
The beam converted from the vertically polarized wave to the circularly polarized wave by the four-wave plate 3 is a mirror 5 which is an object to be measured by the objective lens 4.
Is focused on. The condensed beam is reflected by the mirror 5 such that the rotation direction of the circularly polarized wave is the reverse rotation of the incident direction.
【０００３】反射されたビームは再び対物レンズ４を通
り、１／４波長板３に入射される。１／４波長板３によ
ってビームは円偏波から水平偏波に変換される。水平偏
波に変換されたビームは偏光ビームスプリッタ２を通過
し、集光レンズ６および半円柱レンズ７によって非点収
差を伴って集光される。The reflected beam passes through the objective lens 4 again and is incident on the quarter-wave plate 3. The quarter-wave plate 3 converts the beam from circular polarization to horizontal polarization. The beam converted into the horizontally polarized wave passes through the polarization beam splitter 2 and is condensed by the condenser lens 6 and the semi-cylindrical lens 7 with astigmatism.
【０００４】図６は図１に示した焦点誤差検出装置にお
けるレーザビーム形状の変化過程を示す図である。レー
ザ発振器１から出射されたレーザ光はビームエクスパン
ド用の凹レンズ９と凸レンズ１０を通過して偏光ビーム
スプリッタ２に入射される。偏光ビームスプリッタ２か
ら１／４波長板３および対物レンズ４を通過した光ビー
ムはミラー５で反射され、対物レンズ４，１／４波長板
３およびビームスプリッタ２を介して集光レンズ６によ
って屈折される。この屈折したビームは半円柱レンズ７
によって水平あるいは垂直方向の成分のみが再び屈折さ
れる。水平方向成分のビームは４分割フォトダイオード
８よりも半円柱レンズ７に近い位置に集光し、垂直方向
成分のビームは４分割フォトダイオード８よりも遠い位
置に集光する。４分割フォトダイオード８の位置でのビ
ーム形状は、このような非点収差によって円形ないしは
楕円形となる。FIG. 6 is a diagram showing a changing process of the laser beam shape in the focus error detecting device shown in FIG. The laser light emitted from the laser oscillator 1 passes through a concave lens 9 and a convex lens 10 for beam expansion and is incident on the polarization beam splitter 2. The light beam that has passed from the polarization beam splitter 2 through the quarter-wave plate 3 and the objective lens 4 is reflected by the mirror 5, and is refracted by the condenser lens 6 through the objective lens 4, the quarter-wave plate 3 and the beam splitter 2. To be done. This refracted beam is a semi-cylindrical lens 7
Only the horizontal or vertical component is refracted again by. The horizontal component beam is condensed at a position closer to the semi-cylindrical lens 7 than the four-division photodiode 8, and the vertical component beam is condensed at a position farther than the four-division photodiode 8. The beam shape at the position of the four-division photodiode 8 becomes circular or elliptical due to such astigmatism.
【０００５】[0005]
【発明が解決しようとする課題】上述の図５および図６
で示した光学系において、非点収差を生じるためには、
集光レンズ６と半円柱レンズ７のように２つ光学素子が
必要となる。また、集光レンズ６と半円柱レンズ７の間
隔を離して配置しなければならないため、光学系全体の
長さが長くなってしまうという欠点があった。5 and 6 described above.
In the optical system shown in, in order to produce astigmatism,
Two optical elements such as the condenser lens 6 and the semi-cylindrical lens 7 are required. Further, since the condenser lens 6 and the semi-cylindrical lens 7 must be arranged apart from each other, there is a drawback that the length of the entire optical system becomes long.
【０００６】それゆえに、この発明の主たる目的は、回
折格子を用いることにより、装置を小型化かつ軽量化で
き、装置全体の価格を安価にし得る焦点誤差検出装置を
提供することである。Therefore, a main object of the present invention is to provide a focus error detecting device which can reduce the size and weight of the device and can reduce the cost of the entire device by using the diffraction grating.
【０００７】[0007]
【課題を解決するための手段】この発明は光源からの光
を光学系で測定対象物に導き、その反射光を受光するこ
とによって焦点の誤差を検出する焦点誤差検出装置にお
いて、反射光の経路に設けられ、ガラス面上に複数の楕
円形状の縞パターンを有する回折格子を備え、回折格子
に平面波を照射することによって、その透過光が非点収
差を生ずるように構成される。SUMMARY OF THE INVENTION According to the present invention, a path of reflected light is provided in a focus error detecting device for detecting a focus error by guiding light from a light source to an object to be measured by an optical system and receiving the reflected light. And a diffraction grating having a plurality of elliptical stripe patterns on the glass surface, and the transmitted light produces astigmatism by irradiating the diffraction grating with a plane wave.
【０００８】より好ましくは、回折格子表面にはブレー
ズを施したものが用いられ、回折格子は反射光の光軸に
対して傾けて取付けられ、１次回折光が集光する位置を
光軸から外される。More preferably, a blazed grating is used on the surface of the diffraction grating, and the diffraction grating is attached so as to be inclined with respect to the optical axis of the reflected light, and the position where the first-order diffracted light is focused is outside the optical axis. To be done.
【０００９】[0009]
【作用】この発明に係る焦点誤差検出装置は、反射光の
経路に回折格子を設け、その回折格子に単波長光を照射
することによってその透過光が非点収差を生じるので、
従来のように集光レンズや半円柱レンズを用いる必要が
なくなり、光学系を小型化かつ軽量にすることができ
る。In the focus error detecting device according to the present invention, since a diffraction grating is provided in the path of the reflected light and the transmitted light produces astigmatism by irradiating the diffraction grating with a single wavelength light,
There is no need to use a condenser lens or a semi-cylindrical lens as in the conventional case, and the optical system can be made compact and lightweight.
【００１０】[0010]
【実施例】図１はこの発明の一実施例の光学系を示す図
である。図１において、この実施例では、前述の図５に
示した集光レンズ６と半円柱レンズ７に代えて回折格子
１１が設けられる。この回折格子１１は反射光が非点収
差を生じるように設けられるものである。1 is a diagram showing an optical system according to an embodiment of the present invention. In FIG. 1, in this embodiment, a diffraction grating 11 is provided instead of the condenser lens 6 and the semi-cylindrical lens 7 shown in FIG. The diffraction grating 11 is provided so that the reflected light causes astigmatism.
【００１１】図２は図１に示した回折格子の一例を示す
図である。図２において、回折格子１１はガラス基板１
２上に図２（ａ）に示すような楕円パターン１３が形成
されたものであり、図５および図６に示した集光レンズ
６と半円柱レンズ７の両方の機能を備えている。回折格
子１１はクロム，チタンなどを蒸着したガラス基板１２
のフォトレジストをコーティングし、レーザ描画装置ま
たは電子ビーム描画装置によって、図２（ａ）に示すよ
うな楕円パターンを描画し、そのガラス基板１２を図２
（ｃ）に示すようにクロムエッチングするかまたは図２
（ｂ）に示すようにガラスエッチングの処理を施すこと
によって形成される。FIG. 2 is a diagram showing an example of the diffraction grating shown in FIG. In FIG. 2, the diffraction grating 11 is a glass substrate 1.
2 is formed with an elliptical pattern 13 as shown in FIG. 2A, and has the functions of both the condenser lens 6 and the semi-cylindrical lens 7 shown in FIGS. 5 and 6. The diffraction grating 11 is a glass substrate 12 on which chromium, titanium, etc. are deposited.
2 is coated with a photoresist, and an elliptical pattern as shown in FIG. 2A is drawn by a laser drawing device or an electron beam drawing device.
Chrome etching as shown in (c) or FIG.
It is formed by performing a glass etching process as shown in (b).
【００１２】図３は図２に示した回折格子を反射光の光
路に挿入した例を示す図である。図３に示すように、回
折格子１１と４分割フォトダイオード８は１次回折光の
集光する位置が０次光と重ならないように光軸に対して
傾けて取付けられる。偏光ビームスプリッタ２を通過し
てきた反射光が、回折格子１１に入射すると、素通りす
る０次光と光の回折現象による回折光とが発生する。こ
の実施例では、回折格子１１で発生する１次回折光のみ
のパワーを４分割フォトダイオード８で検知する。FIG. 3 is a diagram showing an example in which the diffraction grating shown in FIG. 2 is inserted in the optical path of reflected light. As shown in FIG. 3, the diffraction grating 11 and the four-division photodiode 8 are attached so as to be inclined with respect to the optical axis so that the position where the 1st-order diffracted light is focused does not overlap with the 0th-order light. When the reflected light that has passed through the polarization beam splitter 2 is incident on the diffraction grating 11, a 0th-order light that passes through and a diffracted light due to the diffraction phenomenon of light are generated. In this embodiment, the power of only the first-order diffracted light generated by the diffraction grating 11 is detected by the four-division photodiode 8.
【００１３】図４はこの発明に用いられる回折格子の他
の例を示す断面図である。前述のごとく、４分割フォト
ダイオード８は回折格子１１による１次回折光のパワー
を検知しているが、素通りしてくる０次光のパワーが強
ければ、１次回折光を検知できない場合がある。そこ
で、図４（ａ）に示すように、回折格子の断面を鋸歯状
または図４（ｂ）に示すようにステップ状に形成するこ
とによって、１次回折光のパワーを増加させ、０次回折
光のパワーを減少させることができる。FIG. 4 is a sectional view showing another example of the diffraction grating used in the present invention. As described above, the four-division photodiode 8 detects the power of the first-order diffracted light by the diffraction grating 11, but the first-order diffracted light may not be detected if the power of the 0th-order light passing through is strong. Therefore, as shown in FIG. 4A, the cross section of the diffraction grating is formed in a sawtooth shape or a step shape as shown in FIG. Power can be reduced.
【００１４】[0014]
【発明の効果】以上のように、この発明によれば、ガラ
ス面上に複数の楕円形状の縞パターンを有する回折格子
を反射光の経路に設けたことによって、研磨を施す屈折
型のレンズを用いる場合に比べて安価に製作できる。し
かも、集光レンズと半円柱レンズの機能を１つの回折格
子で達成できるので、装置を小型化できかつ軽量にな
り、装置全体の価格も安くできる。As described above, according to the present invention, a refraction-type lens for polishing is provided by providing a diffraction grating having a plurality of elliptical stripe patterns on a glass surface in the path of reflected light. It can be manufactured at a lower cost than when used. Moreover, since the functions of the condenser lens and the semi-cylindrical lens can be achieved by one diffraction grating, the device can be downsized and lightweight, and the cost of the entire device can be reduced.
【図１】この発明の一実施例の光学系を示す図である。FIG. 1 is a diagram showing an optical system of an embodiment of the present invention.
【図２】この発明の一実施例に用いられる回折格子の一
例を示す図である。FIG. 2 is a diagram showing an example of a diffraction grating used in an embodiment of the present invention.
【図３】この発明の一実施例において１次回折光の軸を
ずらした例を示す図である。FIG. 3 is a diagram showing an example in which the axis of the first-order diffracted light is shifted in the embodiment of the present invention.
【図４】この発明に用いられる回折格子の他の例を示す
断面図である。FIG. 4 is a cross-sectional view showing another example of the diffraction grating used in the present invention.
【図５】従来の焦点誤差検出装置の光学系を示す図であ
る。FIG. 5 is a diagram showing an optical system of a conventional focus error detection device.
【図６】図５に示したレーザビームの形状の変化過程を
説明するための図である。6A and 6B are views for explaining a changing process of the shape of the laser beam shown in FIG.
１ レーザ発振器 ２ 偏光ビームスプリッタ ３ １／４波長板 ４ 対物レンズ ５ ミラー ８ ４分割フォトダイオード １１ 回折格子 1 Laser Oscillator 2 Polarization Beam Splitter 3 1/4 Wave Plate 4 Objective Lens 5 Mirror 8 4-Division Photodiode 11 Diffraction Grating
Claims (3)
き、その反射光を受光することによって焦点の誤差を検
出する焦点誤差検出装置において、 前記反射光の経路に設けられ、ガラス面上に複数の楕円
形状の縞パターンを有する回折格子を備え、 前記回折格子に平面波を照射することによって、その透
過光が非点収差を生ずるようにしたことを特徴とする、
焦点誤差検出装置。1. A focus error detection device for detecting a focus error by guiding light from a light source to an object to be measured by an optical system and receiving reflected light thereof, wherein the glass surface is provided in the path of the reflected light. A diffraction grating having a plurality of elliptical stripe patterns on the top, by irradiating the diffraction grating with a plane wave, characterized in that the transmitted light causes astigmatism,
Focus error detector.
たものが用いられることを特徴とする、請求項１の焦点
誤差検出装置。2. The focus error detecting device according to claim 1, wherein a blazed surface is used for the diffraction grating surface.
して傾けて取付けられ、１次回折光が集光する位置を光
軸より外したことを特徴とする、請求項１の焦点誤差検
出装置。3. The focus error according to claim 1, wherein the diffraction grating is attached so as to be inclined with respect to the optical axis of the reflected light, and the position where the first-order diffracted light is condensed is off the optical axis. Detection device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20407792A JPH0650717A (en) | 1992-07-30 | 1992-07-30 | Focal point error detector |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP20407792A JPH0650717A (en) | 1992-07-30 | 1992-07-30 | Focal point error detector |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0650717A true JPH0650717A (en) | 1994-02-25 |
Family
ID=16484400
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP20407792A Withdrawn JPH0650717A (en) | 1992-07-30 | 1992-07-30 | Focal point error detector |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0650717A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012226816A (en) * | 2011-04-22 | 2012-11-15 | Panasonic Corp | Optical pickup device |
-
1992
- 1992-07-30 JP JP20407792A patent/JPH0650717A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012226816A (en) * | 2011-04-22 | 2012-11-15 | Panasonic Corp | Optical pickup device |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| KR920018502A (en) | Imaging device | |
| US4748333A (en) | Surface displacement sensor with opening angle control | |
| JP2001304918A (en) | Lattice interference-type optical encoder | |
| US5859439A (en) | Apparatus for aligning semiconductor wafer using mixed light with different wavelengths | |
| EP0458354B1 (en) | A compact reticle/wafer alignment system | |
| JPS61198012A (en) | Surface inspecting device | |
| JPH02185722A (en) | Optical head device | |
| JPH0650717A (en) | Focal point error detector | |
| JPS59231736A (en) | Focus and tracking error detector | |
| JP3065380B2 (en) | Etching rate monitor | |
| JP3619571B2 (en) | Focus detection apparatus and design method for optical microscope | |
| JP3494148B2 (en) | Focus detection device and laser inspection processing device | |
| JP2000097657A (en) | Interferometer | |
| JP3751123B2 (en) | Relative position detector | |
| JPS63191328A (en) | Optical head device | |
| US5939710A (en) | Optical pickup system incorporating therein a beam splitter having a phase layer | |
| JPH01303632A (en) | Optical disk device | |
| JPH11325848A (en) | Aspherical surface shape measurement device | |
| JP2744289B2 (en) | Optical head | |
| JPH10260007A (en) | Relative position detecting device | |
| JPH07104131B2 (en) | Method and device for separating diffracted light | |
| JPS61130816A (en) | Linear encoder | |
| KR0119729B1 (en) | Optical pick-up apparatus | |
| JPH09288444A (en) | Confocal optical device and hologram exposure device | |
| JPH01259208A (en) | Optical surface shape measuring instrument |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A300 | Withdrawal of application because of no request for examination |
Free format text: JAPANESE INTERMEDIATE CODE: A300 Effective date: 19991005 |