JP2004006440A - Laser apparatus, exposure head, and exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high luminance laser light source, and an exposure head and an exposure device that acquires deep focal depth. <P>SOLUTION: In an optical fiber of a bundle-like fiber optical source 66, a core diameter is uniform, and a clad diameter of an emitting end is made smaller than that of an incidence end, to make a light emitting region small. The angle of a luminous flux that is made incident from the bundle-like fiber optical source 66 with high luminance through a lens system 77 to a DMD 50 becomes smaller, and the angle of a luminous flux that is made incident to a scanned surface 56 also becomes smaller. That is, the focal depth becomes deeper. <P>COPYRIGHT: (C)2004,JPO

Description

【０１３１】
表１から分かるように、１対の組合せレンズは、回転対称の２つの非球面レンズから構成されている。光入射側に配置された第１のレンズの光入射側の面を第１面、光出射側の面を第２面とすると、第１面は非球面形状である。また、光出射側に配置された第２のレンズの光入射側の面を第３面、光出射側の面を第４面とすると、第４面が非球面形状である。
【０１３２】
表１において、面番号Ｓｉはｉ番目（ｉ＝１〜４）の面の番号を示し、曲率半径ｒｉはｉ番目の面の曲率半径を示し、面間隔ｄｉはｉ番目の面とｉ＋１番目の面との光軸上の面間隔を示す。面間隔ｄｉ値の単位はミリメートル（ｍｍ）である。屈折率Ｎｉはｉ番目の面を備えた光学要素の波長４０５ｎｍに対する屈折率の値を示す。
【０１３３】
下記表２に、第１面及び第４面の非球面データを示す。
【０１３４】
【表２】

【０１３５】
上記の非球面データは、非球面形状を表す下記式（Ａ）における係数で表される。
【０１３６】
【数１】

【０１３７】
上記式（Ａ）において各係数を以下の通り定義する。
Ｚ：光軸から高さρの位置にある非球面上の点から、非球面の頂点の接平面（光軸に垂直な平面）に下ろした垂線の長さ（ｍｍ）
ρ：光軸からの距離（ｍｍ）
Ｋ：円錐係数
Ｃ：近軸曲率（１／ｒ、ｒ：近軸曲率半径）
ａｉ：第ｉ次（ｉ＝３〜１０）の非球面係数
表２に示した数値において、記号“Ｅ”は、その次に続く数値が１０を底とした“ぺき指数″であることを示し、その１０を底とした指数関数で表される数値が“Ｅ”の前の数値に乗算されることを示す。例えば、「１．０Ｅ−０２」であれば、「１．０×１０^−２」であることを示す。
【０１３８】
図２７は、上記表１及び表２に示す１対の組合せレンズによって得られる照明光の光量分布を示している。横軸は光軸からの座標を示し、縦軸は光量比（％）を示す。なお、比較のために、図２６に、補正を行わなかった場合の照明光の光量分布（ガウス分布）を示す。図２６及び図２７から分かるように、光量分布補正光学系で補正を行うことにより、補正を行わなかった場合と比べて、略均一化された光量分布が得られている。これにより、露光ヘッドにおける光の利用効率を落とさずに、均一なレーザ光でムラなく露光を行うことができる。
【０１３９】
［他の結像光学系］
上記の第１の実施の形態では、露光ヘッドに使用するＤＭＤの光反射側に、結像光学系として２組のレンズを配置したが、レーザ光を拡大して結像する結像光学系を配置してもよい。ＤＭＤにより反射される光束線の断面積を拡大することで、被露光面における露光エリア面積（画像領域）を所望の大きさに拡大することができる。
【０１４０】
例えば、露光ヘッドを、図２８（Ａ）に示すように、ＤＭＤ５０、ＤＭＤ５０にレーザ光を照射する照明装置１４４、ＤＭＤ５０で反射されたレーザ光を拡大して結像するレンズ系４５４、４５８、ＤＭＤ５０の各画素に対応して多数のマイクロレンズ４７４が配置されたマイクロレンズアレイ４７２、マイクロレンズアレイ４７２の各マイクロレンズに対応して多数のアパーチャ４７８が設けられたアパーチャアレイ４７６、アパーチャを通過したレーザ光を被露光面５６に結像するレンズ系４８０、４８２で構成することができる。
【０１４１】
この露光ヘッドでは、照明装置１４４からレーザ光が照射されると、ＤＭＤ５０によりオン方向に反射される光束線の断面積が、レンズ系４５４、４５８により数倍（例えば、２倍）に拡大される。拡大されたレーザ光は、マイクロレンズアレイ４７２の各マイクロレンズによりＤＭＤ５０の各画素に対応して集光され、アパーチャアレイ４７６の対応するアパーチャを通過する。アパーチャを通過したレーザ光は、レンズ系４８０、４８２により被露光面５６上に結像される。
【０１４２】
この結像光学系では、ＤＭＤ５０により反射されたレーザ光は、拡大レンズ４５４、４５８により数倍に拡大されて被露光面５６に投影されるので、全体の画像領域が広くなる。このとき、マイクロレンズアレイ４７２及びアパーチャアレイ４７６が配置されていなければ、図２８（Ｂ）に示すように、被露光面５６に投影される各ビームスポットＢＳの１画素サイズ（スポットサイズ）が露光エリア４６８のサイズに応じて大きなものとなり、露光エリア４６８の鮮鋭度を表すＭＴＦ（Ｍｏｄｕｌａｔｉｏｎ　Ｔｒａｎｓｆｅｒ　Ｆｕｎｃｔｉｏｎ）特性が低下する。
【０１４３】
一方、マイクロレンズアレイ４７２及びアパーチャアレイ４７６を配置した場合には、ＤＭＤ５０により反射されたレーザ光は、マイクロレンズアレイ４７２の各マイクロレンズによりＤＭＤ５０の各画素に対応して集光される。これにより、図２８（Ｃ）に示すように、露光エリアが拡大された場合でも、各ビームスポットＢＳのスポットサイズを所望の大きさ（例えば、１０μｍ×１０μｍ）に縮小することができ、ＭＴＦ特性の低下を防止して高精細な露光を行うことができる。なお、露光エリア４６８が傾いているのは、画素間の隙間を無くす為にＤＭＤ５０を傾けて配置しているからである。
【０１４４】
また、マイクロレンズの収差によるビームの太りがあっても、アパーチャによって被露光面５６上でのスポットサイズが一定の大きさになるようにビームを整形することができると共に、各画素に対応して設けられたアパーチャを通過させることにより、隣接する画素間でのクロストークを防止することができる。
【０１４５】
更に、照明装置１４４に上記実施の形態と同様に高輝度光源を使用することにより、レンズ４５８からマイクロレンズアレイ４７２の各マイクロレンズに入射する光束の角度が小さくなるので、隣接する画素の光束の一部が入射するのを防止することができる。即ち、高消光比を実現することができる。
【０１４６】
［応用例］
本発明の露光装置は、光ビームで光硬化性樹脂を露光して３次元モデルを造形する光造形装置、光ビームで粉末を焼結させて焼結層を形成し該焼結層を積層して粉末焼結体からなる３次元モデルを造形する積層造形装置等に適宜応用することができる。
【０１４７】
例えば、図３４に本発明を応用した光造形装置の構成を示す。この光造形装置は、上方に開口した容器５５６を備えており、容器５５６内には液状の光硬化性樹脂５５０が収容されている。また、容器５５６内には、平板状の昇降ステージ５５２が配置されており、この昇降ステージ５５２は、容器５５６外に配置された支持部５５４に支持されている。支持部５５４には、雄ねじ部５５４Ａが設けられており、この雄ねじ部５５４Ａは、図示しない駆動モータにより回転可能とされたリードスクリュー５５５が螺合されている。このリードスクリュー５５５の回転に伴い、昇降ステージ５５２が昇降される。
【０１４８】
容器５５６内に収容された光硬化性樹脂５５２の液面上方には、箱状のスキャナ５６２がその長手方向を容器５５６の短手方向に向けて配置されている。スキャナ５６２は、短手方向の両側面に取り付けられた２本の支持アーム５６０により支持されている。なお、スキャナ５６２は、上記実施の形態のスキャナと同じ構成であり、複数の露光ヘッドを備え、これを制御する図示しないコントローラに接続されている。
【０１４９】
また、容器５５６の長手方向の両側面には、副走査方向に延びたガイド５５８が各々設けられている。２本の支持アーム５６０の下端部が、このガイド５５８に副走査方向に沿って往復移動可能に取り付けられている。なお、この光造形装置には、支持アーム５６０と共にスキャナ５６２をガイド５５８に沿って駆動するための図示しない駆動装置が設けられている。
【０１５０】
この光造形装置では、スキャナ５６２は、図示しない駆動装置により、ガイド５５８に沿って副走査方向の上流側から下流側に一定速度で移動される。スキャナ５６２が一定速度で移動されることにより、光硬化性樹脂５５０の液面が走査され、各露光ヘッド毎に帯状の硬化領域が形成される。スキャナ５６２による１回の副走査により１層分の硬化が終了すると、スキャナ５６２は、図示しない駆動装置により、ガイド５５８に沿って最上流側にある原点に復帰する。次に、図示しない駆動モータによりリードスクリュー５５５を回転させて昇降ステージ５５２を所定量降下させ、光硬化性樹脂５５０の硬化部分を液面下に沈め、硬化部分上方を液状の光硬化性樹脂５５０で満たす。そして、再度、スキャナ５６２による副走査が行われる。このように、副走査による露光（硬化）とステージの降下とを繰り返し行い、硬化部分が積み重ねられることにより３次元モデルが形成される。上記スキャナ５６２の露光ヘッドに、本発明の高輝度レーザ装置を用いることにより、深い焦点深度を得ることができ、高速且つ高精細に造形を行うことができる。
【０１５１】
【発明の効果】
本発明によれば、高輝度のレーザ装置が提供される。また、本発明の露光装置及び露光ヘッドは、この高輝度のレーザ装置を用いることにより、深い焦点深度を得ることができると共に、という効果を奏する。また、面状の露光ビームの場合には、周辺部のビームぼけを抑制することができる、という効果が得られる。更に、高輝度のレーザ装置として合波レーザ光源を用いた場合には、露光装置及び露光ヘッドの高出力化及び低コスト化を図ることができる、という効果が得られる。
【図面の簡単な説明】
【図１】第１の実施の形態に係る露光装置の外観を示す斜視図である。
【図２】第１の実施の形態に係る露光装置のスキャナの構成を示す斜視図である。
【図３】（Ａ）は感光材料に形成される露光済み領域を示す平面図であり、（Ｂ）は各露光ヘッドによる露光エリアの配列を示す図である。
【図４】第１の実施の形態に係る露光装置の露光ヘッドの概略構成を示す斜視図である。
【図５】（Ａ）は図４に示す露光ヘッドの構成を示す光軸に沿った副走査方向の断面図であり、（Ｂ）は（Ａ）の側面図である。
【図６】デジタルマイクロミラーデバイス（ＤＭＤ）の構成を示す部分拡大図である。
【図７】（Ａ）及び（Ｂ）はＤＭＤの動作を説明するための説明図である。
【図８】（Ａ）及び（Ｂ）は、ＤＭＤを傾斜配置しない場合と傾斜配置する場合とで、露光ビームの配置及び走査線を比較して示す平面図である。
【図９】（Ａ）はファイバアレイ光源の構成を示す斜視図であり、（Ｂ）は（Ａの部分拡大図であり、（Ｃ）及び（Ｄ）はレーザ出射部における発光点の配列を示す平面図である。
【図１０】マルチモード光ファイバの構成を示す図である。
【図１１】合波レーザ光源の構成を示す平面図である。
【図１２】レーザモジュールの構成を示す平面図である。
【図１３】図１２に示すレーザモジュールの構成を示す側面図である。
【図１４】図１２に示すレーザモジュールの構成を示す部分側面図である。
【図１５】（Ａ）及び（Ｂ）は、従来の露光装置における焦点深度と第１の実施の形態に係る露光装置における焦点深度との相違を示す光軸に沿った断面図である。
【図１６】（Ａ）及び（Ｂ）は、ＤＭＤの使用領域の例を示す図である。
【図１７】（Ａ）はＤＭＤの使用領域が適正である場合の側面図であり、（Ｂ）は（Ａ）の光軸に沿った副走査方向の断面図である。
【図１８】スキャナによる１回の走査で感光材料を露光する露光方式を説明するための平面図である。
【図１９】（Ａ）及び（Ｂ）はスキャナによる複数回の走査で感光材料を露光する露光方式を説明するための平面図である。
【図２０】レーザアレイの構成を示す斜視図である。
【図２１】（Ａ）はマルチキャビティレーザの構成を示す斜視図であり、（Ｂ）は（Ａ）に示すマルチキャビティレーザをアレイ状に配列したマルチキャビティレーザアレイの斜視図である。
【図２２】合波レーザ光源の他の構成を示す平面図である。
【図２３】合波レーザ光源の他の構成を示す平面図である。
【図２４】（Ａ）は合波レーザ光源の他の構成を示す平面図であり、（Ｂ）は（Ａ）の光軸に沿った断面図である。
【図２５】光量分布補正光学系による補正の概念についての説明図である。
【図２６】光源がガウス分布で且つ光量分布の補正を行わない場合の光量分布を示すグラフである。
【図２７】光量分布補正光学系による補正後の光量分布を示すグラフである。
【図２８】（Ａ）は結合光学系の異なる他の露光ヘッドの構成を示す光軸に沿った断面図であり、（Ｂ）はマイクロレンズアレイ等を使用しない場合に被露光面に投影される光像を示す平面図であり、（Ｃ）はマイクロレンズアレイ等を使用した場合に被露光面に投影される光像を示す平面図である。
【図２９】従来のファイバ光源の構成を示す光軸に沿った断面図である。
【図３０】第２の実施の形態に係る露光装置の露光ヘッドの概略構成を示す斜視図である。
【図３１】（Ａ）は図３０に示す露光ヘッドの構成を示す光軸に沿った断面図であり、（Ｂ）は（Ａ）の側面図である。
【図３２】グレーティング・ライト・バルブ（ＧＬＶ）の構成を示す部分拡大図である。
【図３３】（Ａ）及び（Ｂ）はＧＬＶの動作を説明するための説明図である。
【図３４】本発明を光造形装置に応用した例を示す斜視図である。
【符号の説明】
ＬＤ１〜ＬＤ７　ＧａＮ系半導体レーザ
１０　ヒートブロック
１１〜１７　コリメータレンズ
２０　集光レンズ
３０　マルチモード光ファイバ
５０　デジタル・マイクロミラー・デバイス（ＤＭＤ）
５３　反射光像（露光ビーム）
５４、５８　レンズ系
５６　走査面（被露光面）
６４　レーザモジュール
６６　ファイバアレイ光源
６８　レーザ出射部
７３　組合せレンズ
１５０　感光材料
１５２　ステージ
１６２　スキャナ
１６６　露光ヘッド
１６８　露光エリア
１７０　露光済み領域[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laser apparatus, an exposure head, and an exposure apparatus, and in particular, a high-intensity laser apparatus suitable for illuminating a spatial light modulation element and a light beam modulated by the spatial light modulation element according to image data. The present invention relates to an exposure head that exposes a material, and an exposure apparatus that includes the exposure head.
[0002]
[Prior art]
Conventionally, various exposure apparatuses that perform image exposure with a light beam modulated in accordance with image data using a spatial light modulation element such as a digital micromirror device (DMD) have been proposed. For example, the DMD is a mirror device in which a number of micromirrors whose reflection surfaces change in response to a control signal are two-dimensionally arranged on a semiconductor substrate such as silicon. An exposure apparatus using this DMD is As shown in FIG. 15A, the light source 1 that irradiates laser light, the lens system 2 that collimates the laser light emitted from the light source 1, and the DMD 3 and DMD 3 that are arranged at substantially the focal position of the lens system 2 are reflected. It comprises lens systems 4 and 6 that form an image of the laser beam on the scanning surface 5. In this exposure apparatus, each of the micromirrors of the DMD 3 is controlled on and off by a control device (not shown) by a control signal generated according to image data or the like to modulate laser light, and image exposure is performed with the modulated laser light. Yes.
[0003]
As shown in FIG. 29, the light source 1 collimates the single semiconductor laser 7, the single multimode optical fiber 8, and the laser light emitted from the semiconductor laser 7 to the end face of the multimode optical fiber 8. A plurality of structural units including a pair of collimating lenses 9 to be coupled are arranged, and the multimode optical fiber 8 is a bundled fiber light source that is bundled (bundled).
[0004]
Usually, a laser having an output of about 30 mW (milliwatt) is used as the semiconductor laser 7, and an optical fiber having a core diameter of 50 μm, a cladding diameter of 125 μm, and an NA (numerical aperture) of 0.2 is used as the multimode optical fiber 8. ing. Therefore, in order to obtain an output of about 1 W (watt), the multi-mode optical fiber 8 of the above-mentioned structural unit must be bundled in a total of 48 of 8 × 6, and the diameter of the light emitting point is about 1 mm. It becomes.
[0005]
[Problems to be solved by the invention]
However, the conventional light source has a problem that the diameter of the light emitting point when bundled becomes large, and as a result, a sufficient depth of focus cannot be obtained when a high-resolution exposure head is configured. In particular, in the case of ultra-high resolution exposure with a beam diameter of about 1 μm, a sufficient depth of focus cannot be obtained. Further, the beam blur around the area of the planar exposure beam occurs.
[0006]
Furthermore, when a conventional exposure head is configured as a high-power exposure head, the number of optical fibers to be bundled is increased, which not only increases the cost, but also increases the diameter of the light emitting point, thereby increasing the depth of focus. There was a problem that became shallow.
[0007]
The present invention has been made to solve the above problems, and an object of the present invention is to provide a high-intensity laser device. Another object of the present invention is to provide an exposure head and an exposure apparatus capable of obtaining a deep depth of focus. Still another object of the present invention is to provide an exposure head and an exposure apparatus with high output and low cost.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a laser apparatus of the present invention is a laser apparatus provided with a fiber light source that emits laser light incident from an incident end of an optical fiber from its exit end, and the optical fiber has a core diameter. And an optical fiber having a uniform cladding diameter at the output end and smaller than the cladding diameter at the input end.
[0009]
The laser apparatus of the present invention includes a fiber light source that emits laser light incident from the incident end of the optical fiber from the output end. As this optical fiber, the core diameter is uniform and the cladding diameter of the output end is incident. Since an optical fiber smaller than the cladding diameter at the end is used, the light emitting portion diameter of the light source can be reduced and high luminance can be achieved.
[0010]
The fiber light source described above may be, for example, a fiber light source having a configuration in which a single semiconductor laser is coupled to the incident end of one optical fiber. However, a combination of a plurality of laser beams to be incident on each of the optical fibers. A wave laser light source is preferred. High output can be obtained by using a combined laser light source. Moreover, each of the light emitting points at the emission end of the optical fiber of a plurality of fiber light sources can be arranged in an array to form a fiber array light source, or each of the light emitting points can be arranged in a bundle to form a fiber bundle light source. Even in the case of bundling or arraying in this way, the number of optical fibers to be bundled or arrayed to obtain the same light output is small, and the cost is low. Furthermore, since the number of optical fibers is small, the light emitting area when bundled or arrayed is further reduced. That is, the brightness is increased.
[0011]
The combined laser light source, for example, (1) condenses laser light emitted from each of the plurality of semiconductor lasers, one optical fiber, and the plurality of semiconductor lasers, and collects the condensed beam of the optical fiber. A condensing optical system coupled to the incident end, (2) a multi-cavity laser having a plurality of light emitting points, one optical fiber, and laser light emitted from each of the light emitting points And (3) a plurality of multi-cavity lasers, a single optical fiber, and the plurality of multi-fibers. And a condensing optical system that condenses laser light emitted from each of the plurality of light emitting points of the cavity laser and couples the condensing beam to the incident end of the optical fiber.
[0012]
The cladding diameter at the exit end of the optical fiber is preferably smaller than 125 μm, more preferably 80 μm or less, and particularly preferably 60 μm or less from the viewpoint of reducing the diameter of the light emitting point. An optical fiber having a uniform core diameter and a cladding diameter at the output end smaller than the cladding diameter at the input end can be configured by, for example, combining a plurality of optical fibers having the same core diameter but different cladding diameters. Further, by configuring the plurality of optical fibers so as to be detachable with connectors, the replacement becomes easy when the light source module is partially damaged.
[0013]
In order to achieve the above object, the exposure head of the present invention includes a laser device of the present invention and a large number of pixel portions whose light modulation states change according to control signals, which are two-dimensionally arranged on the substrate. And a spatial light modulation element that modulates the laser light emitted from the laser device, and an optical system that forms an image on the exposure surface of the laser light modulated by each pixel portion. The exposure apparatus of the present invention is characterized by comprising the exposure head of the present invention and a moving means for moving the exposure head relative to the exposure surface.
[0014]
In the exposure head of the present invention and the exposure apparatus of the present invention, the spatial modulation element modulates the laser beam from the laser device to control the exposure. However, since the laser device includes the high-intensity laser device of the present invention, The depth of focus can be obtained. Further, when a combined laser light source that combines a plurality of laser beams and enters each of the optical fibers is used as a fiber light source that constitutes the laser device, a high output can be obtained, and a bundle or array can be obtained. Even when the number of optical fibers is reduced, the number of optical fibers can be reduced, and the cost can be reduced.
[0015]
As the spatial modulation element, a micromirror device (DMD) configured by two-dimensionally arranging a large number of micromirrors each capable of changing the angle of the reflecting surface according to a control signal on a substrate (for example, a silicon substrate). A digital micromirror device). In addition, the spatial modulation element is configured by arranging in parallel a large number of movable gratings each having a ribbon-like reflecting surface and movable in accordance with a control signal and fixed gratings having a ribbon-like reflecting surface. A one-dimensional grating light valve (GLV) may be used. Furthermore, the spatial modulation element can be configured by a two-dimensional light valve array in which GLVs are arranged in an array. Alternatively, a liquid crystal shutter array in which a large number of liquid crystal cells capable of blocking transmitted light according to each control signal are two-dimensionally arranged on a substrate may be used.
[0016]
On the emission side of these spatial modulation elements, it is preferable to arrange a microlens array provided with a microlens provided corresponding to each pixel portion of the spatial modulation element and condensing laser light for each pixel. When the microlens array is arranged, the laser light modulated by each pixel portion of the spatial modulation element is condensed corresponding to each pixel by each microlens of the microlens array. Even when the area is enlarged, the size of each beam spot can be reduced, and high-definition exposure can be performed.
[0017]
In addition, between the laser device and the spatial modulation element, a collimator lens that converts the light beam from the laser device into a parallel light beam, and the ratio of the light beam width in the peripheral part to the light beam width in the central part near the optical axis is on the incident side. The light beam width at each exit position is changed so that the exit side becomes smaller compared to each other, and the light amount distribution of the laser beam converted into a parallel beam by the collimator lens is substantially uniform on the irradiated surface of the spatial modulation element. It is preferable to arrange a light amount distribution correction optical system that corrects so as to be.
[0018]
According to this light quantity distribution correcting optical system, for example, light having the same light flux width on the incident side has a larger light flux width in the central part than in the peripheral part on the outgoing side. The width is smaller than the central part. In this way, since the light beam in the central part can be utilized to the peripheral part, it is possible to illuminate the spatial modulation element with light having a substantially uniform light amount distribution without reducing the light use efficiency as a whole. Thereby, exposure unevenness does not occur on the exposed surface, and high-quality exposure is possible.
[0019]
In the exposure head and the exposure apparatus of the present invention, for the spatial light modulator, a control is generated in which each of a plurality of pixel units smaller than the total number of pixel units arranged on the substrate is generated according to the exposure information. When controlling by a signal, that is, by controlling a part of the pixel parts without controlling all of the pixel parts arranged on the substrate, the transfer speed of the control signal transfers the control signals of all the pixel parts It becomes shorter and the modulation speed of the laser beam can be increased. Thereby, high-speed exposure becomes possible.
[0020]
Conventionally, a gas laser such as an argon laser or a solid-state laser using THG (third harmonic) is generally used for an exposure apparatus (ultraviolet exposure apparatus) that exposes a photosensitive material with laser light in the ultraviolet region. However, there is a problem that the apparatus is large and maintenance is troublesome, and the exposure speed is slow. The exposure apparatus of the present invention can be an ultraviolet exposure apparatus by using a GaN (gallium nitride) semiconductor laser having a wavelength of 350 to 450 nm as the laser apparatus. According to this ultraviolet exposure apparatus, it is possible to reduce the size and cost of the apparatus and to perform high-speed and high-definition exposure as compared with the conventional ultraviolet exposure apparatus.
[0021]
Further, the exposure apparatus of the present invention is an optical modeling apparatus that forms a three-dimensional model by exposing a photocurable resin with a light beam, and forms a sintered layer by sintering powder with a light beam. The present invention can be appropriately applied to a layered manufacturing apparatus that forms a three-dimensional model made of a powder sintered body by stacking.
[0022]
For example, according to each control signal, the modeling tank which accommodates photocurable resin, the support stand for supporting the modeling object provided in the modeling tank so that raising / lowering is possible, the laser apparatus which irradiates a laser beam, respectively A number of pixel portions whose light modulation states change are two-dimensionally arranged on the substrate, and a spatial light modulation element that modulates the laser light emitted from the laser device, and the laser light modulated in each pixel portion An optical system that forms an image on the liquid level of the photocurable resin contained in the modeling tank, and a moving unit that moves the exposure head relative to the liquid level of the photocurable resin. In the optical modeling apparatus provided, by using the laser apparatus of the present invention, high-speed and high-definition modeling is possible. A specific device configuration is described in Japanese Patent Application No. 2001-274360.
[0023]
Also, a modeling tank that contains powder that is sintered by light irradiation, a support base for supporting a modeled object that can be moved up and down in the modeling tank, a laser device that emits laser light, and a control signal for each A large number of pixel portions whose light modulation states change according to the two-dimensional arrangement on the substrate, a spatial light modulation element that modulates the laser light emitted from the laser device, and the laser light modulated by each pixel portion In an additive manufacturing apparatus comprising: an exposure head including an optical system that forms an image on the surface of the powder stored in the modeling tank; and a moving unit that moves the exposure head relative to the surface of the powder. By using the laser device of the present invention, high-speed and high-definition modeling is possible. A specific device configuration is described in Japanese Patent Application No. 2001-274351.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
(First embodiment)
[Configuration of exposure apparatus]
As shown in FIG. 1, the exposure apparatus according to the embodiment of the present invention includes a flat plate stage 152 that holds a sheet-like photosensitive material 150 by adsorbing to the surface. Two guides 158 extending along the stage moving direction are installed on the upper surface of the thick plate-shaped installation table 156 supported by the four legs 154. The stage 152 is arranged so that the longitudinal direction thereof faces the stage moving direction, and is supported by a guide 158 so as to be reciprocally movable. The exposure apparatus is provided with a drive device (not shown) for driving the stage 152 along the guide 158.
[0025]
A U-shaped gate 160 is provided at the center of the installation table 156 so as to straddle the movement path of the stage 152. Each of the ends of the U-shaped gate 160 is fixed to both side surfaces of the installation table 156. A scanner 162 is provided on one side of the gate 160, and a plurality of (for example, two) detection sensors 164 for detecting the front and rear ends of the photosensitive material 150 are provided on the other side. The scanner 162 and the detection sensor 164 are respectively attached to the gate 160 and fixedly arranged above the moving path of the stage 152. The scanner 162 and the detection sensor 164 are connected to a controller (not shown) that controls them.
[0026]
As shown in FIGS. 2 and 3B, the scanner 162 includes a plurality of (for example, 14) exposure heads 166 arranged in an approximately matrix of m rows and n columns (for example, 3 rows and 5 columns). ing. In this example, four exposure heads 166 are arranged in the third row in relation to the width of the photosensitive material 150. In the case where individual exposure heads arranged in the m-th row and the n-th column are shown, the exposure head 166 is used. _mn Is written.
[0027]
An exposure area 168 by the exposure head 166 has a rectangular shape with a short side in the sub-scanning direction. Therefore, as the stage 152 moves, a strip-shaped exposed area 170 is formed for each exposure head 166 in the photosensitive material 150. In addition, when showing the exposure area by each exposure head arranged in the mth row and the nth column, the exposure area 168 is shown. _mn Is written.
[0028]
Further, as shown in FIGS. 3A and 3B, each of the exposure heads in each row arranged in a line so that the strip-shaped exposed areas 170 are arranged without gaps in the direction orthogonal to the sub-scanning direction. In the arrangement direction, they are shifted by a predetermined interval (natural number times the long side of the exposure area, twice in this embodiment). Therefore, the exposure area 168 in the first row ₁₁ And exposure area 168 ₁₂ The portion that cannot be exposed between the exposure area 168 and the exposure area 168 in the second row ₂₁ And exposure area 168 in the third row ₃₁ And can be exposed.
[0029]
Exposure head 166 ₁₁ ~ 166 _mn As shown in FIGS. 4, 5 (A) and 5 (B), each of them is a digital micromirror device (spatial light modulation element that modulates an incident light beam for each pixel according to image data. DMD) 50. The DMD 50 is connected to a controller (not shown) including a data processing unit and a mirror drive control unit. The data processing unit of this controller generates a control signal for driving and controlling each micromirror in the region to be controlled by the DMD 50 for each exposure head 166 based on the input image data. The area to be controlled will be described later. The mirror drive control unit controls the angle of the reflection surface of each micromirror of the DMD 50 for each exposure head 166 based on the control signal generated by the image data processing unit. The control of the angle of the reflecting surface will be described later.
[0030]
On the light incident side of the DMD 50, a fiber array light source 66 including a laser emitting section in which emission ends (light emitting points) of an optical fiber are arranged in a line along a direction corresponding to the long side direction of the exposure area 168, a fiber A lens system 67 for correcting the laser light emitted from the array light source 66 and condensing it on the DMD, and a mirror 69 for reflecting the laser light transmitted through the lens system 67 toward the DMD 50 are arranged in this order.
[0031]
The lens system 67 includes a pair of combination lenses 71 that collimate the laser light emitted from the fiber array light source 66 and a pair of combination lenses that correct the light quantity distribution of the collimated laser light to be uniform. 73 and a condensing lens 75 that condenses the laser light whose light quantity distribution is corrected on the DMD. With respect to the arrangement direction of the laser emitting ends, the combination lens 73 spreads the light beam at a portion close to the optical axis of the lens and contracts the light beam at a portion away from the optical axis, and with respect to a direction orthogonal to the arrangement direction. Has a function of allowing light to pass through as it is, and corrects the laser light so that the light quantity distribution is uniform.
[0032]
Further, on the light reflection side of the DMD 50, lens systems 54 and 58 for forming an image of the laser light reflected by the DMD 50 on the scanning surface (exposed surface) 56 of the photosensitive material 150 are arranged. The lens systems 54 and 58 are arranged so that the DMD 50 and the exposed surface 56 are in a conjugate relationship.
[0033]
As shown in FIG. 6, the DMD 50 is configured such that a micromirror 62 is supported by a support column on an SRAM cell (memory cell) 60, and a large number of (pixels) (pixels) are formed. For example, the mirror device is configured by arranging 600 × 800 micromirrors in a lattice pattern. Each pixel is provided with a micromirror 62 supported by a support column at the top, and a material having a high reflectance such as aluminum is deposited on the surface of the micromirror 62. The reflectance of the micromirror 62 is 90% or more. A silicon gate CMOS SRAM cell 60 manufactured on a normal semiconductor memory manufacturing line is disposed directly below the micromirror 62 via a support including a hinge and a yoke, and is entirely monolithic (integrated type). ).
[0034]
When a digital signal is written in the SRAM cell 60 of the DMD 50, the micromirror 62 supported by the support is inclined within a range of ± α degrees (for example, ± 10 degrees) with respect to the substrate side on which the DMD 50 is disposed with the diagonal line as the center. It is done. FIG. 7A shows a state in which the micromirror 62 is tilted to + α degrees in the on state, and FIG. 7B shows a state in which the micromirror 62 is tilted to −α degrees in the off state. Therefore, by controlling the inclination of the micromirror 62 in each pixel of the DMD 50 as shown in FIG. 6 according to the image signal, the light incident on the DMD 50 is reflected in the inclination direction of each micromirror 62. .
[0035]
FIG. 6 shows an example of a state in which a part of the DMD 50 is enlarged and the micromirror 62 is controlled to + α degrees or −α degrees. On / off control of each micromirror 62 is performed by a controller (not shown) connected to the DMD 50. A light absorber (not shown) is arranged in the direction in which the light beam is reflected by the micromirror 62 in the off state.
[0036]
Further, it is preferable that the DMD 50 is disposed with a slight inclination so that the short side forms a predetermined angle θ (for example, 1 ° to 5 °) with the sub-scanning direction. 8A shows the scanning trajectory of the reflected light image (exposure beam) 53 by each micromirror when the DMD 50 is not tilted, and FIG. 8B shows the scanning trajectory of the exposure beam 53 when the DMD 50 is tilted. Show.
[0037]
In the DMD 50, a number of micromirror arrays in which a large number (for example, 800) of micromirrors are arranged in the longitudinal direction are arranged in a large number (for example, 600 sets) in the short direction. As shown, by tilting the DMD 50, the pitch P of the scanning locus (scanning line) of the exposure beam 53 by each micromirror is shown. ₁ However, the pitch P of the scanning line when the DMD 50 is not inclined. ₂ It becomes narrower and the resolution can be greatly improved. On the other hand, since the tilt angle of the DMD 50 is very small, the scanning width W when the DMD 50 is tilted. ₂ And the scanning width W when the DMD 50 is not inclined. ₁ Is substantially the same.
[0038]
Further, the same scanning line is overlapped and exposed (multiple exposure) by different micromirror rows. In this way, by performing multiple exposure, it is possible to control a minute amount of the exposure position and to realize high-definition exposure. Further, joints between a plurality of exposure heads arranged in the main scanning direction can be connected without a step by controlling a very small amount of exposure position.
[0039]
Note that the same effect can be obtained by arranging the micromirror rows in a staggered manner by shifting the micromirror rows by a predetermined interval in a direction orthogonal to the sub-scanning direction instead of tilting the DMD 50.
[0040]
As shown in FIG. 9A, the fiber array light source 66 includes a plurality of (for example, six) laser modules 64, and one end of the multimode optical fiber 30 is coupled to each laser module 64. Yes. The other end of the multimode optical fiber 30 is coupled with an optical fiber 31 having the same core diameter as the multimode optical fiber 30 and a cladding diameter smaller than the multimode optical fiber 30, as shown in FIG. A laser emission portion 68 is configured by arranging the emission end portions (light emission points) of the optical fiber 31 in one row along the main scanning direction orthogonal to the sub-scanning direction. As shown in FIG. 9D, the light emitting points can be arranged in two rows along the main scanning direction.
[0041]
As shown in FIG. 9B, the emission end of the optical fiber 31 is sandwiched and fixed between two support plates 65 having a flat surface. Further, a transparent protective plate 63 such as glass is disposed on the light emitting side of the optical fiber 31 in order to protect the end face of the optical fiber 31. The protective plate 63 may be disposed in close contact with the end surface of the optical fiber 31, and is disposed so that the end surface of the optical fiber 31 is sealed with an inert gas such as nitrogen gas or an inert gas containing a small amount of oxygen gas. May be. The exit end of the optical fiber 31 has a high light density and is easy to collect dust and easily deteriorate. However, the protective plate 63 is disposed to reduce the light density and prevent dust from adhering to the end face and deteriorate. Can be delayed.
[0042]
In this example, in order to arrange the emission ends of the optical fibers 31 with a small cladding diameter in a line without any gaps, the multimode optical fiber 30 is placed between two adjacent multimode optical fibers 30 at a portion with a large cladding diameter. Two exit ends of the optical fiber 31 coupled to two adjacent multi-mode optical fibers 30 where the exit ends of the optical fibers 31 coupled to the stacked multi-mode optical fibers 30 are adjacent to each other at a portion where the cladding diameter is large. Are arranged so as to be sandwiched between them.
[0043]
For example, as shown in FIG. 10, an optical fiber 31 having a length of 1 to 30 cm and having a small cladding diameter is coaxially connected to the tip of the multimode optical fiber 30 having a large cladding diameter on the laser light emission side. Can be obtained by linking them together. In the two optical fibers, the incident end face of the optical fiber 31 is fused and joined to the outgoing end face of the multimode optical fiber 30 so that the central axes of both optical fibers coincide. As described above, the diameter of the core 31 a of the optical fiber 31 is the same as the diameter of the core 30 a of the multimode optical fiber 30.
[0044]
In addition, a short optical fiber in which an optical fiber having a short cladding diameter and a large cladding diameter is fused to an optical fiber having a short cladding diameter and a large cladding diameter may be coupled to the output end of the multimode optical fiber 30 via a ferrule or an optical connector. Good. By detachably coupling using a connector or the like, the tip portion can be easily replaced when an optical fiber having a small cladding diameter is broken, and the cost required for exposure head maintenance can be reduced. Hereinafter, the optical fiber 31 may be referred to as an emission end portion of the multimode optical fiber 30.
[0045]
The multimode optical fiber 30 and the optical fiber 31 may be any of a step index type optical fiber, a graded index type optical fiber, and a composite type optical fiber. For example, a step index type optical fiber manufactured by Mitsubishi Cable Industries, Ltd. can be used. In the present embodiment, the multimode optical fiber 30 and the optical fiber 31 are step index type optical fibers, and the multimode optical fiber 30 has a cladding diameter = 125 μm, a core diameter = 25 μm, NA = 0.2, an incident end face. The transmittance of the coat is 99.5% or more, and the optical fiber 31 has a cladding diameter = 60 μm, a core diameter = 25 μm, and NA = 0.2.
[0046]
In general, in laser light in the infrared region, propagation loss increases as the cladding diameter of the optical fiber is reduced. For this reason, a suitable cladding diameter is determined according to the wavelength band of the laser beam. However, the shorter the wavelength, the smaller the propagation loss. In the case of laser light having a wavelength of 405 nm emitted from a GaN-based semiconductor laser, the cladding thickness {(cladding diameter−core diameter) / 2} is set to infrared light in the wavelength band of 800 nm. The propagation loss hardly increases even if it is about ½ of the case of propagating infrared light and about ¼ of the case of propagating infrared light in the 1.5 μm wavelength band for communication. Therefore, the cladding diameter can be reduced to 60 μm.
[0047]
However, the cladding diameter of the optical fiber 31 is not limited to 60 μm. The clad diameter of an optical fiber used in a conventional fiber light source is 125 μm, but the depth of focus becomes deeper as the clad diameter becomes smaller. Therefore, the clad diameter of a multimode optical fiber is preferably 80 μm or less, more preferably 60 μm or less. Preferably, it is 40 μm or less. On the other hand, since the core diameter needs to be at least 3 to 4 μm, the cladding diameter of the optical fiber 31 is preferably 10 μm or more.
[0048]
The laser module 64 is configured by a combined laser light source (fiber light source) shown in FIG. This combined laser light source includes a plurality of (for example, seven) chip-like lateral multimode or single mode GaN-based semiconductor lasers LD1, LD2, LD3, LD4, LD5, LD6, arrayed and fixed on the heat block 10. And LD7, collimator lenses 11, 12, 13, 14, 15, 16, and 17 provided corresponding to each of the GaN-based semiconductor lasers LD1 to LD7, one condenser lens 20, and one multi-lens. Mode optical fiber 30. The number of semiconductor lasers is not limited to seven. A multimode optical fiber having a clad diameter = 60 μm, a core diameter = 50 μm, and NA = 0.2 can receive as many as 20 semiconductor laser beams. The number of fibers can be further reduced.
[0049]
The GaN-based semiconductor lasers LD1 to LD7 all have the same oscillation wavelength (for example, 405 nm), and the maximum output is also all the same (for example, 100 mW for the multimode laser and 30 mW for the single mode laser). As the GaN-based semiconductor lasers LD1 to LD7, lasers having an oscillation wavelength other than the above 405 nm in a wavelength range of 350 nm to 450 nm may be used.
[0050]
As shown in FIGS. 12 and 13, the above-described combined laser light source is housed in a box-shaped package 40 having an upper opening together with other optical elements. The package 40 includes a package lid 41 created so as to close the opening thereof. After the deaeration process, a sealing gas is introduced, and the package 40 and the package lid 41 are closed by closing the opening of the package 40 with the package lid 41. The combined laser light source is hermetically sealed in a closed space (sealed space) formed by 41.
[0051]
A base plate 42 is fixed to the bottom surface of the package 40, and the heat block 10, a condensing lens holder 45 that holds the condensing lens 20, and the multimode optical fiber 30 are disposed on the top surface of the base plate 42. A fiber holder 46 that holds the incident end is attached. The exit end of the multimode optical fiber 30 is drawn out of the package from an opening formed in the wall surface of the package 40.
[0052]
Further, a collimator lens holder 44 is attached to the side surface of the heat block 10, and the collimator lenses 11 to 17 are held. An opening is formed in the lateral wall surface of the package 40, and wiring 47 for supplying a driving current to the GaN-based semiconductor lasers LD1 to LD7 is drawn out of the package through the opening.
[0053]
In FIG. 13, in order to avoid complication of the drawing, only the GaN semiconductor laser LD7 among the plurality of GaN semiconductor lasers is numbered, and only the collimator lens 17 among the plurality of collimator lenses is numbered. doing.
[0054]
FIG. 14 shows the front shape of the attachment part of the collimator lenses 11-17. Each of the collimator lenses 11 to 17 is formed in a shape obtained by cutting a region including the optical axis of a circular lens having an aspherical surface into a long and narrow plane. This elongated collimator lens can be formed, for example, by molding resin or optical glass. The collimator lenses 11 to 17 are closely arranged in the arrangement direction of the light emitting points so that the length direction is orthogonal to the arrangement direction of the light emitting points of the GaN-based semiconductor lasers LD1 to LD7 (left and right direction in FIG. 14).
[0055]
On the other hand, each of the GaN-based semiconductor lasers LD1 to LD7 includes an active layer having a light emission width of 2 μm, and each of the laser beams B1 in a state parallel to the active layer and a divergence angle in a direction perpendicular to the active layer, respectively, for example A laser emitting ~ B7 is used. These GaN-based semiconductor lasers LD1 to LD7 are arranged so that the light emitting points are arranged in a line in a direction parallel to the active layer.
[0056]
Accordingly, in the laser beams B1 to B7 emitted from the respective light emitting points, the direction in which the divergence angle is large coincides with the length direction and the divergence angle is small with respect to the elongated collimator lenses 11 to 17 as described above. Incident light is incident in a state where the direction coincides with the width direction (direction perpendicular to the length direction). That is, the collimator lenses 11 to 17 have a width of 1.1 mm and a length of 4.6 mm, and the horizontal and vertical beam diameters of the laser beams B1 to B7 incident thereon are 0.9 mm and 2. 6 mm. Each of the collimator lenses 11 to 17 has a focal length f. ₁ = 3 mm, NA = 0.6, and lens arrangement pitch = 1.25 mm.
[0057]
The condensing lens 20 is formed by cutting a region including the optical axis of a circular lens having an aspheric surface into a long and narrow shape in parallel planes, and is long in the arrangement direction of the collimator lenses 11 to 17, that is, in a horizontal direction and short in a direction perpendicular thereto. Is formed. The condenser lens 20 has a focal length f. ₂ = 23 mm, NA = 0.2. This condensing lens 20 is also formed by molding resin or optical glass, for example.
[0058]
[Operation of exposure apparatus]
Next, the operation of the exposure apparatus will be described.
[0059]
In each exposure head 166 of the scanner 162, laser beams B1, B2, B3, B4, B5, B6 emitted in a divergent light state from each of the GaN-based semiconductor lasers LD1 to LD7 constituting the combined laser light source of the fiber array light source 66. , And B7 are collimated by corresponding collimator lenses 11-17. The collimated laser beams B <b> 1 to B <b> 7 are collected by the condenser lens 20 and converge on the incident end face of the core 30 a of the multimode optical fiber 30.
[0060]
In this example, the collimator lenses 11 to 17 and the condenser lens 20 constitute a condensing optical system, and the condensing optical system and the multimode optical fiber 30 constitute a multiplexing optical system. That is, the laser beams B1 to B7 condensed as described above by the condenser lens 20 enter the core 30a of the multimode optical fiber 30 and propagate through the optical fiber to be combined with one laser beam B. The light is emitted from the optical fiber 31 coupled to the output end of the multimode optical fiber 30.
[0061]
In each laser module, when the coupling efficiency of the laser beams B1 to B7 to the multimode optical fiber 30 is 0.85 and each output of the GaN-based semiconductor lasers LD1 to LD7 is 30 mW, the light arranged in an array For each of the fibers 31, a combined laser beam B with an output of 180 mW (= 30 mW × 0.85 × 7) can be obtained. Therefore, the output from the laser emitting unit 68 in which the six optical fibers 31 are arranged in an array is about 1 W (= 180 mW × 6).
[0062]
In the laser emitting portion 68 of the fiber array light source 66, light emission points with high luminance are arranged in a line along the main scanning direction as described above. A conventional fiber light source that couples laser light from a single semiconductor laser to a single optical fiber has a low output, so a desired output could not be obtained unless multiple rows are arranged. Since the combined laser light source used in the form has a high output, a desired output can be obtained even with a small number of columns, for example, one column.
[0063]
For example, in a conventional fiber light source in which a semiconductor laser and an optical fiber are coupled on a one-to-one basis, a laser having an output of about 30 mW (milliwatt) is usually used as the semiconductor laser, and the core diameter is 50 μm and the cladding diameter is 125 μm. Since a multimode optical fiber having a numerical aperture (NA) of 0.2 is used, if an output of about 1 W (watt) is to be obtained, 48 multimode optical fibers (8 × 6) must be bundled. The area of the light emitting region is 0.62 mm ² (0.675 mm × 0.925 mm), the luminance at the laser emission unit 68 is 1.6 × 10 6. ⁶ (W / m ² ) The brightness per optical fiber is 3.2 × 10 ⁶ (W / m ² ).
[0064]
On the other hand, in this embodiment, as described above, an output of about 1 W can be obtained with six multimode optical fibers, and the area of the light emitting region at the laser emitting portion 68 is 0.0081 mm. ² (0.325 mm × 0.025 mm), the luminance at the laser emission unit 68 is 123 × 10. ⁶ (W / m ² Thus, the brightness can be increased by about 80 times compared to the conventional case. In addition, the luminance per optical fiber is 90 × 10 ⁶ (W / m ² The brightness can be increased by about 28 times compared to the conventional case.
[0065]
Here, with reference to FIGS. 15A and 15B, the difference in depth of focus between the conventional exposure head and the exposure head of the present embodiment will be described. The diameter of the light emission region of the bundled fiber light source of the conventional exposure head is 0.675 mm, and the diameter of the light emission region of the fiber array light source of the exposure head according to the present embodiment is 0.025 mm. is there. As shown in FIG. 15A, in the conventional exposure head, since the light emitting area of the light source (bundle-shaped fiber light source) 1 is large, the angle of the light beam incident on the DMD 3 increases, and as a result, the light enters the scanning surface 5. The angle of the light beam increases. For this reason, the beam diameter tends to increase with respect to the light condensing direction (shift in the focus direction).
[0066]
On the other hand, as shown in FIG. 15B, in the exposure head of the present embodiment, the diameter of the light emitting region of the fiber array light source 66 is small in the sub-scanning direction, so that the light flux that passes through the lens system 67 and enters the DMD 50 , And as a result, the angle of the light beam incident on the scanning surface 56 is reduced. That is, the depth of focus becomes deep. In this example, the diameter of the light emitting region in the sub-scanning direction is about 30 times that of the conventional one, and a depth of focus substantially corresponding to the diffraction limit can be obtained. Therefore, it is suitable for exposure of a minute spot. This effect on the depth of focus is more prominent and effective as the required light quantity of the exposure head is larger. In this example, the size of one pixel projected on the exposure surface is 10 μm × 10 μm. DMD is a reflective spatial modulation element, but FIGS. 15A and 15B are developed views for explaining the optical relationship.
[0067]
Image data corresponding to the exposure pattern is input to a controller (not shown) connected to the DMD 50 and temporarily stored in a frame memory in the controller. This image data is data representing the density of each pixel constituting the image by binary values (whether or not dots are recorded).
[0068]
The stage 152 that has adsorbed the photosensitive material 150 to the surface is moved at a constant speed from the upstream side to the downstream side of the gate 160 along the guide 158 by a driving device (not shown). When the leading edge of the photosensitive material 150 is detected by the detection sensor 164 attached to the gate 160 when the stage 152 passes under the gate 160, the image data stored in the frame memory is sequentially read out for a plurality of lines. A control signal is generated for each exposure head 166 based on the image data read by the data processing unit. Then, each of the micromirrors of the DMD 50 is controlled on and off for each exposure head 166 based on the generated control signal by the mirror drive control unit.
[0069]
When the DMD 50 is irradiated with laser light from the fiber array light source 66, the laser light reflected when the micromirror of the DMD 50 is in the on state forms an image on the exposed surface 56 of the photosensitive material 150 by the lens systems 54 and 58. Is done. In this manner, the laser light emitted from the fiber array light source 66 is turned on and off for each pixel, and the photosensitive material 150 is exposed in pixel units (exposure area 168) that is approximately the same number as the number of pixels used in the DMD 50. Further, when the photosensitive material 150 is moved at a constant speed together with the stage 152, the photosensitive material 150 is sub-scanned in the direction opposite to the stage moving direction by the scanner 162, and a strip-shaped exposed region 170 is formed for each exposure head 166. It is formed.
[0070]
As shown in FIGS. 16A and 16B, in this embodiment, the DMD 50 has 600 sets of micromirror arrays in which 800 micromirrors are arranged in the main scanning direction, which are arranged in the subscanning direction. However, it is possible to control so that only a part of the micromirror rows (for example, 800 × 100 rows) are driven by the controller.
[0071]
As shown in FIG. 16A, a micromirror array arranged at the center of the DMD 50 may be used, and as shown in FIG. 16B, the micromirror array arranged at the end of the DMD 50 is used. May be used. In addition, when a defect occurs in some of the micromirrors, the micromirror array to be used may be appropriately changed depending on the situation, such as using a micromirror array in which no defect has occurred.
[0072]
Since the data processing speed of the DMD 50 is limited and the modulation speed per line is determined in proportion to the number of pixels used, the modulation speed per line can be increased by using only a part of the micromirror rows. Get faster. On the other hand, in the case of an exposure method in which the exposure head is continuously moved relative to the exposure surface, it is not necessary to use all the pixels in the sub-scanning direction.
[0073]
For example, when only 300 sets are used in 600 micromirror rows, modulation can be performed twice as fast per line as compared to the case of using all 600 sets. Further, when only 200 sets of 600 micromirror arrays are used, modulation can be performed three times faster per line than when all 600 sets are used. That is, an area of 500 mm in the sub-scanning direction can be exposed in 17 seconds. Further, when only 100 sets are used, modulation can be performed 6 times faster per line. That is, an area of 500 mm in the sub-scanning direction can be exposed in 9 seconds.
[0074]
The number of micromirror rows to be used, that is, the number of micromirrors arranged in the sub-scanning direction is preferably 10 or more and 200 or less, and more preferably 10 or more and 100 or less. Since the area per micromirror corresponding to one pixel is 15 μm × 15 μm, when converted to the use area of DMD50, an area of 12 mm × 150 μm or more and 12 mm × 3 mm or less is preferable, and 12 mm × 150 μm or more and 12 mm A region of × 1.5 mm or less is more preferable.
[0075]
If the number of micromirror rows to be used is within the above range, as shown in FIGS. 17A and 17B, the laser light emitted from the fiber array light source 66 is made into substantially parallel light by the lens system 67, and the DMD 50 Can be irradiated. It is preferable that the irradiation area where the laser beam is irradiated by the DMD 50 coincides with the use area of the DMD 50. When the irradiation area is wider than the use area, the utilization efficiency of the laser light is lowered.
[0076]
On the other hand, the diameter of the light beam condensed on the DMD 50 in the sub-scanning direction needs to be reduced according to the number of micromirrors arranged in the sub-scanning direction by the lens system 67, but the number of micromirror rows to be used. Is less than 10, it is not preferable because the angle of the light beam incident on the DMD 50 increases and the depth of focus of the light beam on the scanning surface 56 becomes shallow. Further, the number of micromirror rows to be used is preferably 200 or less from the viewpoint of modulation speed. DMD is a reflective spatial modulation element, but FIGS. 17A and 17B are developed views for explaining the optical relationship.
[0077]
When the sub scanning of the photosensitive material 150 by the scanner 162 is completed and the rear end of the photosensitive material 150 is detected by the detection sensor 164, the stage 152 is moved along the guide 158 by the driving device (not shown) on the most upstream side of the gate 160. Returned to the origin at the point, and again moved along the guide 158 from the upstream side to the downstream side of the gate 160 at a constant speed.
[0078]
As described above, the exposure apparatus of the present embodiment includes the exposure head that illuminates the spatial light modulation element with the fiber array light source in which the emission ends (light emission points) of the optical fiber of the combined laser light source are arranged in an array. ing. In this fiber array light source, since the cladding diameter of the output end of the optical fiber is made smaller than the cladding diameter of the incident end, the diameter of the light emitting portion is further reduced, and the brightness of the fiber array light source is increased. Thereby, an exposure head and an exposure apparatus having a deep depth of focus can be realized. For example, even in the case of ultra-high resolution exposure with a beam diameter of 1 μm or less and a resolution of 0.1 μm or less, a deep depth of focus can be obtained and beam blurring at the periphery of a planar exposure beam can be suppressed. . High-speed and high-definition exposure is possible. Therefore, the exposure apparatus of this embodiment can be used for an exposure process of a thin film transistor (TFT) that requires high resolution.
[0079]
In addition, since a combined laser light source that combines a plurality of laser beams and enters the optical fiber is used, the output at the output end of the optical fiber is increased, and high-power exposure is possible. Furthermore, since the output of each fiber light source is increased, the number of fiber light sources necessary to obtain a desired output is reduced, and the cost of the exposure apparatus can be reduced.
[0080]
In addition, the exposure apparatus of the present embodiment includes a DMD in which 600 sets of micromirror arrays in which 800 micromirrors are arranged in the main scanning direction are arranged in the subscanning direction. Since the control is performed so that only the mirror array is driven, the modulation speed per line is faster than when all the micromirror arrays are driven. This enables high-speed exposure.
[0081]
(Second Embodiment)
The exposure apparatus according to the second embodiment uses a grating light valve (GLV) as a spatial light modulation element used in each exposure head. GLV is a kind of MEMS (Micro Electro Mechanical Systems) type spatial light modulator (SLM), as disclosed in US Pat. No. 5,311,360, for example, and is a reflection diffraction grating type. This is a spatial light modulation element. Since the other points are the same as those of the exposure apparatus according to the first embodiment, description thereof is omitted.
[0082]
Exposure head 166 ₁₁ ~ 166 _mn As shown in FIGS. 30, 31A, and 31B, each is a spatial light modulation element that modulates an incident light beam for each pixel in accordance with image data. In the same manner as in the first embodiment, a fiber array light source 66, a lens system 67, and a mirror 69 are arranged in this order on the light incident side of the GLV 300.
[0083]
The linear GLV 300 is arranged such that the longitudinal direction thereof is parallel to the arrangement direction of the optical fibers of the fiber array light source 66 and the reflection surface of the ribbon-like microbridge of the GLV 300 is substantially parallel to the reflection surface of the mirror 69. The controller is connected to a controller (not shown) for controlling this.
[0084]
As shown in FIG. 32, the GLV 300 is a long substrate 203 made of silicon or the like, on which a large number (for example, 6480) of microbridges 209 having ribbon-like reflecting surfaces are arranged in parallel. In addition, a large number of slits 211 are formed between adjacent microbridges 209. Normally, one pixel is composed of a plurality of (for example, six) microbridges 209 columns, and assuming that one pixel is composed of six microbridge columns, exposure of 1080 pixels is performed with 6480 microbridges. Is possible.
[0085]
As shown in FIGS. 33A and 33B, each microbridge 209 has a single surface of aluminum (or gold, silver, copper, etc.) on the surface of a flexible beam 209a made of silicon nitride (SiNx) or the like. A reflective electrode film 209b made of a layer metal film is formed. Each of the reflective electrode films 209b is connected to a power source through a switch (not shown) by a wiring (not shown).
[0086]
Here, the operation principle of the GLV 300 will be briefly described. In a state where no voltage is applied, the microbridge 209 is spaced apart from the substrate 203 by a predetermined distance. However, when a voltage is applied between the microbridge 209 and the substrate 203, the microbridge 209 is separated from the microbridge 209 by electrostatically induced charges. An electrostatic attraction force is generated between the substrate 203 and the microbridge 209 bends toward the substrate 203 side. When the application of voltage is stopped, the bending is eliminated, and the microbridge 209 is separated from the substrate 203 by elastic recovery. Therefore, by alternately arranging the microbridges to which the voltage is applied and the microbridges to which the voltage is not applied, the diffraction grating can be formed by applying the voltage.
[0087]
FIG. 33A shows a case where no voltage is applied to the microbridge row in pixel units and the microbridge row is in an off state. In the off state, the heights of the reflecting surfaces of the microbridges 209 are all equal, and the reflected light is regularly reflected without any optical path difference. That is, only 0th order diffracted light can be obtained. On the other hand, FIG. 33B shows a case where a voltage is applied to the microbridge row in pixel units and the microbridge row is in an on state. The voltage is applied to every other microbridge 209. In the on state, the central portion of the microbridge 209 bends according to the principle described above, and a reflective surface with steps is alternately formed. That is, a diffraction grating is formed. When laser light is incident on this reflecting surface, an optical path difference is generated between the light reflected by the microbridge 209 having the deflection and the light reflected by the microbridge 209 having no deflection. Folded light is emitted.
[0088]
Therefore, the laser beam incident on the GLV 300 is modulated for each pixel by controlling the microbridge array in each pixel of the GLV 300 by turning on and off the applied voltage in accordance with a control signal by a controller (not shown). And is diffracted in a predetermined direction.
[0089]
Further, on the light reflection side of the GLV 300, that is, the side from which the diffracted light (0th order diffracted light and ± 1st order diffracted light) is emitted, a lens system 54 that forms an image of the diffracted light on the scanning surface (exposed surface) 56, 58 is arranged so that the GLV 300 and the exposed surface 56 are in a conjugate relationship. Further, the GLV 300 is arranged with its ribbon-like reflecting surface inclined in advance by a predetermined angle (for example, 45 °) with respect to the optical axis of the lens system 54 so that the diffracted light is incident on the lens system 54.
[0090]
In FIGS. 31A and 31B, the 0th-order diffracted light is illustrated by a dotted line, and the ± 1st-order diffracted light is illustrated by a solid line. However, the 0th-order diffracted light from the GLV 300 is transmitted in the longitudinal direction of the GLV by the lens system Only focused. Therefore, between the lens system 54 and the lens system 58, a long shielding plate 57 for excluding 0th-order diffracted light from the optical path to the scanning surface 56 has a longitudinal direction orthogonal to the longitudinal direction of the GLV 300. Are arranged as follows.
[0091]
The lens system 54 condenses the incident diffracted light in the longitudinal direction of the GLV 300 and converts it into parallel light in the sub-scanning direction. At the focal position of the 0th-order diffracted light between the lens system 54 and the lens system 58, a long shielding plate 55 for excluding the 0th-order diffracted light from the optical path to the scanning surface 56 has a longitudinal direction of GLV. It arrange | positions so that it may orthogonally cross a direction. Thereby, only the 0th-order diffracted light is selectively excluded.
[0092]
In this exposure head, when image data corresponding to the exposure pattern is input to a controller (not shown) connected to the GLV 300, a control signal is generated based on the image data, and each exposure is performed based on the generated control signal. Each of the micro bridges of the GLV 300 is on / off controlled for each head. As a result, the photosensitive material 150 is exposed in units of approximately the same number of pixels as the GLV 300, and a strip-shaped exposed region is formed for each exposure head by sub-scanning by the movement of the stage 152.
[0093]
In the exposure apparatus according to the present embodiment, the GLV 300 is a long spatial light modulation element with a narrow width in the short side direction, so that it is difficult to efficiently illuminate, but as described in the first embodiment, As a light source for illuminating the GLV, a high-intensity fiber array light source in which the output ends of the optical fibers of the combined laser light source are arranged in an array is used, and the cladding diameter of the output end of the optical fiber is made larger than the cladding diameter of the incident end Since it is made smaller, the diameter of the beam emitted from the laser emitting unit 68 in the sub-scanning direction becomes smaller, and the angle of the light beam that passes through the lens system 67 and the like and enters the GLV 300 becomes smaller. As a result, the GLV 300 can be illuminated efficiently and a deep depth of focus can be obtained. Further, since a combined laser light source is used, exposure with high output becomes possible, and the cost of the exposure apparatus can be reduced.
[0094]
Next, a modification of the exposure apparatus described above will be described.
[Applications of exposure equipment]
The exposure apparatus described above is, for example, exposure of a dry film resist (DFR) in a manufacturing process of a printed wiring board (PWB) and a color filter in a manufacturing process of a liquid crystal display (LCD). It can be suitably used for applications such as formation, DFR exposure in a TFT manufacturing process, and DFR exposure in a plasma display panel (PDP) manufacturing process.
[0095]
Furthermore, the above exposure apparatus can be used for various laser processing such as laser ablation, sintering, and lithography in which a part of the material is removed by evaporation, scattering, etc. by laser irradiation. The above exposure apparatus has a high output and can be exposed at a high speed and a long focal depth, so that it can be used for fine processing such as laser ablation. For example, instead of performing development processing, the resist is removed according to a pattern by ablation to create a PWB, or the above exposure apparatus can be used to form a PWB pattern by ablation directly without using a resist. it can. It can also be used to form microchannels with a groove width of several tens of μm in a lab-on-chip in which many solutions are mixed, reacted, separated, detected, etc. on glass or plastic chips.
[0096]
In particular, the exposure apparatus described above uses a GaN-based semiconductor laser as a fiber array light source, and therefore can be suitably used for the laser processing described above. That is, the GaN-based semiconductor laser can be driven with a short pulse, and sufficient power can be obtained for laser ablation and the like. In addition, since it is a semiconductor laser, it can be driven at a high repetition rate of about 10 MHz unlike a solid-state laser having a low driving speed, and high-speed exposure is possible. Furthermore, since metal has a large light absorption rate of laser light having a wavelength of around 400 nm and can be easily converted into thermal energy, laser ablation and the like can be performed at high speed.
[0097]
When exposing a liquid resist used for patterning a TFT and a liquid resist used for patterning a color filter, in order to eliminate sensitivity reduction (desensitization) due to oxygen inhibition, the exposure is performed in a nitrogen atmosphere. It is preferable to expose the exposure material. Exposure in a nitrogen atmosphere suppresses oxygen inhibition of the photopolymerization reaction, increases the sensitivity of the resist, and enables high-speed exposure.
[0098]
In the exposure apparatus, either a photon mode photosensitive material in which information is directly recorded by exposure or a heat mode photosensitive material in which information is recorded by heat generated by exposure can be used. When using a photon mode photosensitive material, a GaN-based semiconductor laser, a wavelength conversion solid-state laser, or the like is used for the laser device. When using a heat mode photosensitive material, an AlGaAs-based semiconductor laser (infrared laser), A solid state laser is used.
[0099]
[Other spatial modulation elements]
In the first embodiment, an example in which the DMD micromirror is partially driven has been described. However, the length in the direction corresponding to the predetermined direction is longer than the length in the direction intersecting the predetermined direction. Even if a long and narrow DMD in which a number of micromirrors that can change the angle of the reflecting surface in accordance with the control signal is used is two-dimensionally arranged, the number of micromirrors that control the angle of the reflecting surface is reduced. Similarly, the modulation speed can be increased.
[0100]
In the first and second embodiments described above, the exposure head provided with the DMD or the GLV as the spatial modulation element has been described. For example, a MEMS (Micro Electro Mechanical Systems) type spatial modulation element (SLM; Spatial Light Modulator) is used. ) And all the pixel portions arranged on the substrate even when a spatial modulation element other than the MEMS type is used, such as an optical element (PLZT element) that modulates transmitted light by an electro-optic effect or a liquid crystal light shutter (FLC). On the other hand, by using a part of the pixel portions, it is possible to increase the modulation speed per pixel and per main scanning line, so that the same effect can be obtained.
[0101]
Note that MEMS is a general term for micro systems that integrate micro-sized sensors, actuators, and control circuits based on micro-machining technology based on the IC manufacturing process. It means a spatial modulation element that is driven by the electromechanical operation used.
[0102]
[Other exposure methods]
As shown in FIG. 18, as in the above embodiment, the entire surface of the photosensitive material 150 may be exposed by one scanning in the X direction by the scanner 162, as shown in FIGS. 19 (A) and 19 (B). As shown in the figure, after scanning the photosensitive material 150 in the X direction by the scanner 162, the scanner 162 is moved one step in the Y direction and scanned in the X direction. The entire surface of the photosensitive material 150 may be exposed. In this example, the scanner 162 includes 18 exposure heads 166.
[0103]
[Other laser devices (light sources)]
In the above embodiment, an example using a fiber array light source including a plurality of combined laser light sources has been described. However, the laser device is not limited to a fiber array light source in which combined laser light sources are arrayed. For example, a fiber array light source obtained by arraying fiber light sources including one optical fiber that emits laser light incident from a single semiconductor laser having one light emitting point can be used.
[0104]
In the above embodiment, as shown in FIG. 20, a combined laser light source including a laser array in which a plurality of (for example, seven) chip-shaped semiconductor lasers LD1 to LD7 are arranged on the heat block 100. However, the combined laser light source is not limited to one that combines laser beams emitted from a plurality of chip-shaped semiconductor lasers.
[0105]
A chip-shaped multicavity laser 110 in which a plurality of (for example, five) light emitting points 110a shown in FIG. 21A is arranged in a predetermined direction is known. For example, as shown in FIG. 22, a combined laser light source including this multi-cavity laser 110 can be used. This combined laser light source is configured to include a multi-cavity laser 110, one multi-mode optical fiber 130, and a condensing lens 120. The multi-cavity laser 110 can be composed of, for example, a GaN-based laser diode having an oscillation wavelength of 405 nm.
[0106]
Since the multicavity laser 110 can arrange the light emitting points with higher positional accuracy than the case where the chip-shaped semiconductor lasers are arranged, it is easy to multiplex laser beams emitted from the respective light emitting points. However, as the number of light emitting points increases, the multicavity laser 110 is likely to be bent at the time of laser manufacturing. Therefore, the number of light emitting points 110a is preferably 5 or less.
[0107]
In the above configuration, each of the laser beams B emitted from each of the plurality of light emitting points 110 a of the multicavity laser 110 is collected by the condenser lens 120 and enters the core 130 a of the multimode optical fiber 130. The laser light incident on the core 130a propagates in the optical fiber, is combined into one, and is emitted.
[0108]
A plurality of light emitting points 110 a of the multi-cavity laser 110 are juxtaposed within a width substantially equal to the core diameter of the multi-mode optical fiber 130, and a focal point substantially equal to the core diameter of the multi-mode optical fiber 130 is used as the condenser lens 120. By using a convex lens of a distance or a rod lens that collimates the outgoing beam from the multicavity laser 110 only in a plane perpendicular to the active layer, the coupling efficiency of the laser beam B to the multimode optical fiber 130 can be increased. it can.
[0109]
Further, as shown in FIG. 21B, a multi-cavity laser array in which a plurality of multi-cavity lasers 110 are arranged on the heat block 100 in the same direction as the arrangement direction of the light emitting points 110a of each chip is used. 23, a combined laser light source including a laser array 140 in which a plurality of (for example, nine) multi-cavity lasers 110 are arranged at equal intervals on the heat block 111 can be configured. The plurality of multi-cavity lasers 110 are arranged and fixed in the same direction as the arrangement direction of the light emitting points 110a of each chip.
[0110]
This combined laser light source includes a laser array 140, a plurality of lens arrays 114 arranged corresponding to each multi-capability laser 110, and a single lens arranged between the laser array 140 and the plurality of lens arrays 114. A rod lens 113, one multimode optical fiber 130, and a condenser lens 120 are provided. The lens array 114 includes a plurality of microlenses corresponding to the emission points of the multi-capability laser 110.
[0111]
In the above configuration, each of the laser beams B emitted from each of the plurality of light emitting points 10a of the plurality of multi-cavity lasers 110 is condensed in a predetermined direction by the rod lens 113 and then each microlens of the lens array 114. Is collimated. The collimated laser beam L is condensed by the condenser lens 120 and enters the core 130a of the multimode optical fiber 130. The laser light incident on the core 130a propagates in the optical fiber, is combined into one, and is emitted.
[0112]
Still another example of the combined laser light source will be described. In this combined laser light source, as shown in FIGS. 24A and 24B, a heat block 182 having an L-shaped cross section in the optical axis direction is mounted on a substantially rectangular heat block 180, and two heats are provided. A storage space is formed between the blocks. On the upper surface of the L-shaped heat block 182, a plurality of (for example, two) multi-cavity lasers 110 in which a plurality of light emitting points (for example, five) are arranged in an array form the light emitting points 110a of each chip. It is arranged and fixed at equal intervals in the same direction as the arrangement direction.
[0113]
A concave portion is formed in the substantially rectangular heat block 180, and a plurality of (for example, two) light emitting points (for example, five) are arranged in an array on the upper surface of the space side of the heat block 180. The multi-cavity laser 110 is arranged such that its emission point is located on the same vertical plane as the emission point of the laser chip arranged on the upper surface of the heat block 182.
[0114]
On the laser beam emission side of the multi-cavity laser 110, a collimator lens array 184 in which collimator lenses are arranged corresponding to the light emission points 110a of the respective chips is arranged. In the collimating lens array 184, the length direction of each collimating lens coincides with the direction in which the divergence angle of the laser beam is large (the fast axis direction), and the width direction of each collimating lens is in the direction in which the divergence angle is small (slow axis direction). They are arranged to match. Thus, by collimating and integrating the collimating lenses, the space utilization efficiency of the laser light can be improved, the output of the combined laser light source can be increased, and the number of parts can be reduced and the cost can be reduced. .
[0115]
Further, on the laser beam emitting side of the collimating lens array 184, there is one multimode optical fiber 130, and a condensing lens 120 that condenses and combines the laser beam at the incident end of the multimode optical fiber 130. Has been placed.
[0116]
In the above configuration, each of the laser beams B emitted from each of the plurality of light emitting points 10a of the plurality of multi-cavity lasers 110 arranged on the laser blocks 180 and 182 is collimated by the collimating lens array 184, The light is condensed by the condensing lens 120 and enters the core 130 a of the multimode optical fiber 130. The laser light incident on the core 130a propagates in the optical fiber, is combined into one, and is emitted.
[0117]
As described above, this combined laser light source can achieve particularly high output by the multi-stage arrangement of multi-cavity lasers and the array of collimating lenses. By using this combined laser light source, a higher-intensity fiber array light source or bundle fiber light source can be formed, which is particularly suitable as a fiber light source constituting the laser light source of the exposure apparatus of the present invention.
[0118]
It should be noted that a laser module in which each of the above combined laser light sources is housed in a casing and the emission end portion of the multimode optical fiber 130 is pulled out from the casing can be configured.
[0119]
In the above embodiment, another optical fiber having the same core diameter as the multimode optical fiber and a cladding diameter smaller than the multimode optical fiber is coupled to the output end of the multimode optical fiber of the combined laser light source. However, for example, a multimode optical fiber having a cladding diameter of 125 μm, 80 μm, 60 μm, or the like can be used without coupling another optical fiber to the output end. Good. Thus, it is possible to approach a point light source by forming two or three fiber light sources in which a large number of beams are combined into an array or bundling, and coupling an optical fiber having a small cladding diameter to the emission end. As a result, the configuration of the optical system using the present light source becomes easy. Therefore, this light source can constitute a low-cost and high-performance optical system.
[0120]
[Light distribution correction optical system]
In the above embodiment, the light amount distribution correcting optical system including a pair of combination lenses is used for the exposure head. This light quantity distribution correcting optical system changes the light beam width at each emission position so that the ratio of the light beam width at the peripheral part to the light beam width at the central part near the optical axis is smaller on the output side than on the incident side. When the parallel light beam from the light source is irradiated onto the DMD, the light amount distribution on the irradiated surface is corrected so as to be substantially uniform. Hereinafter, the operation of this light quantity distribution correcting optical system will be described.
[0121]
First, as shown in FIG. 25A, the case where the entire luminous flux widths (total luminous flux widths) H0 and H1 are the same for the incident luminous flux and the outgoing luminous flux will be described. In FIG. 25A, the portions denoted by reference numerals 51 and 52 virtually indicate the entrance surface and the exit surface in the light quantity distribution correction optical system.
[0122]
In the light quantity distribution correcting optical system, it is assumed that the light flux widths h0 and h1 of the light beam incident on the central part near the optical axis Z1 and the light beam incident on the peripheral part are the same (h0 = hl). The light quantity distribution correcting optical system expands the light beam width h0 of the incident light beam in the central portion with respect to the light having the same light beam width h0 and h1 on the incident side, and conversely with respect to the incident light beam in the peripheral portion. Thus, the light beam width h1 is reduced. That is, the width h10 of the outgoing light beam at the center and the width h11 of the outgoing light beam at the periphery are set to satisfy h11 <h10. In terms of the ratio of the luminous flux width, the ratio “h11 / h10” of the luminous flux width in the peripheral portion to the luminous flux width in the central portion on the emission side is smaller than the ratio (h1 / h0 = 1) on the incident side ( (H11 / h10) <1).
[0123]
By changing the light flux width in this way, the light flux in the central part, which normally has a large light quantity distribution, can be utilized in the peripheral part where the light quantity is insufficient, and the overall light utilization efficiency is not reduced. In addition, the light quantity distribution on the irradiated surface is made substantially uniform. The degree of uniformity is, for example, such that the unevenness in the amount of light in the effective area is within 30%, preferably within 20%.
[0124]
The actions and effects of such a light quantity distribution correcting optical system are the same when the entire light flux width is changed between the incident side and the exit side (FIGS. 25B and 25C).
[0125]
FIG. 25B shows a case where the entire light flux width H0 on the incident side is “reduced” to the width H2 and emitted (H0> H2). Even in such a case, the light quantity distribution correcting optical system uses the light flux widths h0 and h1 that are the same on the incident side, and the light flux width h10 in the central portion is larger than that in the peripheral portion on the outgoing side. In addition, the light flux width h11 in the peripheral portion is made smaller than that in the central portion. Considering the reduction rate of the light beam, the reduction rate with respect to the incident light beam in the central part is made smaller than that in the peripheral part, and the reduction rate with respect to the incident light beam in the peripheral part is made larger than that in the central part. Also in this case, the ratio “H11 / H10” of the light flux width in the peripheral portion to the light flux width in the central portion is smaller than the ratio (h1 / h0 = 1) on the incident side ((h11 / h10) <1). .
[0126]
FIG. 25C shows a case where the entire light flux width H0 on the incident side is “enlarged” by the width Η3 and emitted (H0 <H3). Even in such a case, the light quantity distribution correcting optical system uses the light flux widths h0 and h1 that are the same on the incident side, and the light flux width h10 in the central portion is larger than that in the peripheral portion on the outgoing side. In addition, the light flux width h11 in the peripheral portion is made smaller than that in the central portion. Considering the expansion rate of the light beam, the expansion rate for the incident light beam in the central portion is made larger than that in the peripheral portion, and the expansion rate for the incident light beam in the peripheral portion is made smaller than that in the central portion. Also in this case, the ratio “h11 / h10” of the light flux width in the peripheral portion to the light flux width in the central portion is smaller than the ratio (h1 / h0 = 1) on the incident side ((h11 / h10) <1). .
[0127]
As described above, the light amount distribution correcting optical system changes the light beam width at each emission position, and the ratio of the light beam width in the peripheral part to the light beam width in the central part near the optical axis Z1 is larger on the outgoing side than on the incident side. Since the light has the same light flux width on the incident side, the light flux width in the central portion is larger than that in the peripheral portion, and the light flux width in the peripheral portion is larger than that in the central portion. Get smaller. As a result, it is possible to make use of the light beam at the center part to the peripheral part, and it is possible to form a light beam cross-section with a substantially uniform light amount distribution without reducing the light use efficiency of the entire optical system.
[0128]
Next, an example of specific lens data of a pair of combination lenses used as a light quantity distribution correcting optical system is shown. In this example, lens data in the case where the light amount distribution in the cross section of the emitted light beam is a Gaussian distribution as in the case where the light source is a laser array light source is shown. When one semiconductor laser is connected to the incident end of the single mode optical fiber, the light quantity distribution of the emitted light beam from the optical fiber becomes a Gaussian distribution. The present embodiment can also be applied to such a case. Further, the present invention can be applied to a case where the light amount in the central portion near the optical axis is larger than the light amount in the peripheral portion, for example, by reducing the core diameter of the multi-mode optical fiber and approaching the configuration of the single mode optical fiber.
[0129]
Table 1 below shows basic lens data.
[0130]
[Table 1]

[0131]
As can be seen from Table 1, the pair of combination lenses is composed of two rotationally symmetric aspherical lenses. If the light incident side surface of the first lens disposed on the light incident side is the first surface and the light exit side surface is the second surface, the first surface is aspherical. In addition, when the surface on the light incident side of the second lens disposed on the light emitting side is the third surface and the surface on the light emitting side is the fourth surface, the fourth surface is aspherical.
[0132]
In Table 1, the surface number Si indicates the number of the i-th surface (i = 1 to 4), the curvature radius ri indicates the curvature radius of the i-th surface, and the surface interval di indicates the i-th surface and the i + 1-th surface. The distance between surfaces on the optical axis is shown. The unit of the surface interval di value is millimeter (mm). The refractive index Ni indicates the value of the refractive index with respect to the wavelength of 405 nm of the optical element having the i-th surface.
[0133]
Table 2 below shows the aspheric data of the first surface and the fourth surface.
[0134]
[Table 2]

[0135]
The aspheric data is expressed by a coefficient in the following formula (A) that represents the aspheric shape.
[0136]
[Expression 1]

[0137]
In the above formula (A), each coefficient is defined as follows.
Z: Length of a perpendicular line (mm) drawn from a point on the aspheric surface at a height ρ from the optical axis to the tangent plane (plane perpendicular to the optical axis) of the apex of the aspheric surface
ρ: Distance from optical axis (mm)
K: Conic coefficient
C: Paraxial curvature (1 / r, r: Paraxial radius of curvature)
ai: i-th order (i = 3 to 10) aspheric coefficient
In the numerical values shown in Table 2, the symbol “E” indicates that the subsequent numerical value is a “pecker exponent” with a base of 10, and the numerical value represented by an exponential function with the base 10 is “ Indicates that the value before E ″ is multiplied. For example, if “1.0E-02”, “1.0 × 10 ^-2 ".
[0138]
FIG. 27 shows a light amount distribution of illumination light obtained by the pair of combination lenses shown in Tables 1 and 2 above. The horizontal axis indicates coordinates from the optical axis, and the vertical axis indicates the light amount ratio (%). For comparison, FIG. 26 shows a light amount distribution (Gaussian distribution) of illumination light when correction is not performed. As can be seen from FIG. 26 and FIG. 27, a light amount distribution that is substantially uniform is obtained by performing correction using the light amount distribution correcting optical system as compared with the case where correction is not performed. Thereby, it is possible to carry out exposure with uniform laser light without reducing the use efficiency of light in the exposure head.
[0139]
[Other imaging optics]
In the first embodiment, two sets of lenses are arranged as the imaging optical system on the light reflection side of the DMD used for the exposure head. However, the imaging optical system for enlarging the laser beam to form an image is used. You may arrange. By expanding the cross-sectional area of the light beam reflected by the DMD, the exposure area area (image area) on the exposed surface can be expanded to a desired size.
[0140]
For example, as shown in FIG. 28A, the exposure head is configured to illuminate the DMD 50, the illumination device 144 for irradiating the DMD 50 with laser light, the lens systems 454, 458, the DMD 50 for enlarging the laser light reflected by the DMD 50, and forming an image. A microlens array 472 in which a large number of microlenses 474 are arranged corresponding to each of the pixels, an aperture array 476 in which a large number of apertures 478 are provided corresponding to each microlens of the microlens array 472, and a laser that has passed through the aperture It can be configured by lens systems 480 and 482 that form an image of light on the exposed surface 56.
[0141]
In this exposure head, when laser light is irradiated from the illumination device 144, the cross-sectional area of the light beam reflected by the DMD 50 in the ON direction is enlarged several times (for example, twice) by the lens systems 454 and 458. . The expanded laser light is condensed corresponding to each pixel of the DMD 50 by each microlens of the microlens array 472, and passes through the corresponding aperture of the aperture array 476. The laser light that has passed through the aperture is imaged on the exposed surface 56 by the lens systems 480 and 482.
[0142]
In this imaging optical system, the laser light reflected by the DMD 50 is magnified several times by the magnifying lenses 454 and 458 and projected onto the exposed surface 56, so that the entire image area is widened. At this time, if the microlens array 472 and the aperture array 476 are not arranged, as shown in FIG. 28B, one pixel size (spot size) of each beam spot BS projected onto the exposed surface 56 is exposed. MTF (Modulation Transfer Function) characteristics representing the sharpness of the exposure area 468 are reduced depending on the size of the area 468.
[0143]
On the other hand, when the microlens array 472 and the aperture array 476 are arranged, the laser light reflected by the DMD 50 is condensed corresponding to each pixel of the DMD 50 by each microlens of the microlens array 472. Thereby, as shown in FIG. 28C, even when the exposure area is enlarged, the spot size of each beam spot BS can be reduced to a desired size (for example, 10 μm × 10 μm), and the MTF characteristics are obtained. It is possible to perform high-definition exposure while preventing a decrease in the image quality. The exposure area 468 is tilted because the DMD 50 is tilted and arranged in order to eliminate a gap between pixels.
[0144]
In addition, even if the beam is thick due to the aberration of the microlens, the beam can be shaped by the aperture so that the spot size on the exposed surface 56 becomes a constant size, and corresponding to each pixel. By passing the provided aperture, it is possible to prevent crosstalk between adjacent pixels.
[0145]
Furthermore, by using a high-intensity light source for the illumination device 144 as in the above embodiment, the angle of the light beam incident on each microlens of the microlens array 472 from the lens 458 is reduced, so that the light flux of adjacent pixels can be reduced. Part of the incident can be prevented. That is, a high extinction ratio can be realized.
[0146]
[Application example]
The exposure apparatus of the present invention is an optical modeling apparatus that exposes a photocurable resin with a light beam to form a three-dimensional model, a powder is sintered with a light beam to form a sintered layer, and the sintered layer is laminated. Thus, the present invention can be appropriately applied to an additive manufacturing apparatus for modeling a three-dimensional model made of a powder sintered body.
[0147]
For example, FIG. 34 shows a configuration of an optical modeling apparatus to which the present invention is applied. This stereolithography apparatus includes a container 556 that opens upward, and a liquid photocurable resin 550 is accommodated in the container 556. Further, a flat plate-like lifting stage 552 is disposed in the container 556, and the lifting stage 552 is supported by a support portion 554 disposed outside the container 556. The support portion 554 is provided with a male screw portion 554A. The male screw portion 554A is screwed with a lead screw 555 that can be rotated by a drive motor (not shown). As the lead screw 555 rotates, the elevating stage 552 is raised and lowered.
[0148]
A box-shaped scanner 562 is disposed above the liquid level of the photo-curable resin 552 accommodated in the container 556 with its longitudinal direction directed in the short direction of the container 556. The scanner 562 is supported by two support arms 560 attached to both side surfaces in the lateral direction. The scanner 562 has the same configuration as the scanner of the above-described embodiment, includes a plurality of exposure heads, and is connected to a controller (not shown) that controls the exposure heads.
[0149]
Further, guides 558 extending in the sub-scanning direction are provided on both side surfaces of the container 556 in the longitudinal direction. The lower ends of the two support arms 560 are attached to the guide 558 so as to be capable of reciprocating along the sub-scanning direction. This stereolithography apparatus is provided with a driving device (not shown) for driving the scanner 562 along the guide 558 together with the support arm 560.
[0150]
In this stereolithography apparatus, the scanner 562 is moved at a constant speed from the upstream side to the downstream side in the sub-scanning direction along the guide 558 by a driving device (not shown). By moving the scanner 562 at a constant speed, the liquid level of the photocurable resin 550 is scanned, and a band-shaped cured region is formed for each exposure head. When the curing for one layer is completed by one sub-scanning by the scanner 562, the scanner 562 returns to the origin on the most upstream side along the guide 558 by a driving device (not shown). Next, the lead screw 555 is rotated by a drive motor (not shown) to lower the elevating stage 552 by a predetermined amount, the cured portion of the photocurable resin 550 is submerged below the liquid surface, and the liquid photocurable resin 550 is placed above the cured portion. Fill with. Then, sub-scanning by the scanner 562 is performed again. As described above, the exposure (curing) by the sub-scanning and the lowering of the stage are repeated, and the cured portions are stacked to form a three-dimensional model. By using the high-intensity laser device of the present invention for the exposure head of the scanner 562, a deep depth of focus can be obtained, and modeling can be performed at high speed and with high definition.
[0151]
【The invention's effect】
According to the present invention, a high-intensity laser device is provided. In addition, the exposure apparatus and the exposure head of the present invention can obtain a deep depth of focus by using this high-intensity laser apparatus. Further, in the case of a planar exposure beam, an effect that the beam blur at the peripheral portion can be suppressed is obtained. Further, when a combined laser light source is used as a high-intensity laser device, an effect that the exposure apparatus and the exposure head can be increased in output and cost can be obtained.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an external appearance of an exposure apparatus according to a first embodiment.
FIG. 2 is a perspective view showing a configuration of a scanner of the exposure apparatus according to the first embodiment.
FIG. 3A is a plan view showing an exposed area formed on a photosensitive material, and FIG. 3B is a view showing an arrangement of exposure areas by each exposure head.
FIG. 4 is a perspective view showing a schematic configuration of an exposure head of the exposure apparatus according to the first embodiment.
5A is a cross-sectional view in the sub-scanning direction along the optical axis showing the configuration of the exposure head shown in FIG. 4, and FIG. 5B is a side view of FIG.
FIG. 6 is a partially enlarged view showing a configuration of a digital micromirror device (DMD).
7A and 7B are explanatory diagrams for explaining the operation of the DMD. FIG.
FIGS. 8A and 8B are plan views showing the arrangement of exposure beams and scanning lines in a case where the DMD is not inclined and in a case where the DMD is inclined. FIG.
9A is a perspective view showing the configuration of a fiber array light source, FIG. 9B is a partially enlarged view of A, and FIGS. 9C and 9D show the arrangement of light emitting points in a laser emitting section. FIG.
FIG. 10 is a diagram showing a configuration of a multimode optical fiber.
FIG. 11 is a plan view showing a configuration of a combined laser light source.
FIG. 12 is a plan view showing the configuration of a laser module.
13 is a side view showing the configuration of the laser module shown in FIG. 12. FIG.
14 is a partial side view showing the configuration of the laser module shown in FIG. 12. FIG.
FIGS. 15A and 15B are cross-sectional views along the optical axis showing the difference between the depth of focus in the conventional exposure apparatus and the depth of focus in the exposure apparatus according to the first embodiment. FIGS.
FIGS. 16A and 16B are diagrams showing examples of DMD usage areas; FIGS.
FIG. 17A is a side view when the DMD use area is appropriate, and FIG. 17B is a cross-sectional view in the sub-scanning direction along the optical axis of FIG.
FIG. 18 is a plan view for explaining an exposure method for exposing a photosensitive material by one scanning by a scanner.
FIGS. 19A and 19B are plan views for explaining an exposure method for exposing a photosensitive material by a plurality of scans by a scanner. FIGS.
FIG. 20 is a perspective view showing a configuration of a laser array.
21A is a perspective view showing the configuration of a multi-cavity laser, and FIG. 21B is a perspective view of a multi-cavity laser array in which the multi-cavity lasers shown in FIG.
FIG. 22 is a plan view showing another configuration of the combined laser light source.
FIG. 23 is a plan view showing another configuration of the combined laser light source.
24A is a plan view showing another configuration of the combined laser light source, and FIG. 24B is a cross-sectional view taken along the optical axis of FIG.
FIG. 25 is an explanatory diagram of a concept of correction by a light amount distribution correction optical system.
FIG. 26 is a graph showing the light amount distribution when the light source has a Gaussian distribution and the light amount distribution is not corrected.
FIG. 27 is a graph showing a light amount distribution after correction by a light amount distribution correcting optical system.
FIG. 28A is a cross-sectional view along the optical axis showing the configuration of another exposure head having a different coupling optical system, and FIG. 28B is projected onto the exposure surface when a microlens array or the like is not used. FIG. 6C is a plan view showing a light image projected on an exposed surface when a microlens array or the like is used.
FIG. 29 is a cross-sectional view along the optical axis showing the configuration of a conventional fiber light source.
FIG. 30 is a perspective view showing a schematic configuration of an exposure head of the exposure apparatus according to the second embodiment.
31A is a cross-sectional view along the optical axis showing the configuration of the exposure head shown in FIG. 30, and FIG. 31B is a side view of FIG.
FIG. 32 is a partially enlarged view showing a configuration of a grating light valve (GLV).
33A and 33B are explanatory diagrams for explaining the operation of the GLV.
FIG. 34 is a perspective view showing an example in which the present invention is applied to an optical modeling apparatus.
[Explanation of symbols]
LD1-LD7 GaN semiconductor laser
10 Heat block
11-17 Collimator lens
20 Condensing lens
30 Multimode optical fiber
50 Digital Micromirror Device (DMD)
53 Reflected light image (exposure beam)
54, 58 Lens system
56 Scanning surface (exposed surface)
64 laser module
66 Fiber array light source
68 Laser emitting part
73 Combination lens
150 Photosensitive material
152 stages
162 Scanner
166 Exposure head
168 Exposure area
170 Exposed area

Claims (18)

A laser device including a fiber light source that emits laser light incident from an incident end of an optical fiber from an output end thereof,
A laser device using, as the optical fiber, an optical fiber having a uniform core diameter and a smaller exit end cladding diameter than an incident end cladding diameter. The laser device according to claim 1, wherein the fiber light source multiplexes a plurality of laser beams to enter each of the optical fibers. The fiber light source collects a plurality of semiconductor lasers, a single optical fiber, and laser light emitted from each of the plurality of semiconductor lasers, and couples a focused beam to an incident end of the optical fiber. The laser device according to claim 1, comprising a combined laser light source including an optical optical system. The laser device according to claim 3, wherein the semiconductor laser is a multi-cavity laser having a plurality of light emitting points. The fiber light source is configured to condense a multi-cavity laser having a plurality of light emitting points, a single optical fiber, and laser light emitted from each of the plurality of light emitting points, and to collect a condensed beam of the optical fiber. The laser device according to claim 1, comprising a combined laser light source including a condensing optical system coupled to an incident end. The laser device includes a plurality of the fiber light sources, and a fiber array light source in which each of emission points at an emission end of an optical fiber of the plurality of fiber light sources is arranged in an array, or a fiber bundle light source arranged in a bundle 6. The laser device according to claim 1, wherein the laser device is configured. The laser apparatus according to claim 1, wherein a cladding diameter of the emission end is 80 μm or less. The laser apparatus according to claim 1, wherein a cladding diameter of the emission end is 60 μm or less. 9. The laser device according to claim 1, wherein the optical fiber is configured by combining a plurality of optical fibers having the same core diameter but different cladding diameters. 10. The laser device according to any one of claims 1 to 9, wherein the optical fiber is configured by detachably connecting a plurality of optical fibers with a connector. The laser device according to claim 1, wherein the laser beam is a laser beam having a wavelength of 350 to 450 nm. The laser device according to claim 3, wherein the semiconductor laser is a gallium nitride semiconductor laser. A laser device according to any one of claims 1 to 12,
A spatial light modulation element that modulates the laser light emitted from the laser device, in which a large number of pixel portions each having a light modulation state that changes in response to a control signal are two-dimensionally arranged on the substrate;
An optical system that forms an image on the exposure surface of the laser beam modulated in each pixel unit;
Exposure head equipped with. 14. The spatial modulation element according to claim 13, wherein each of the spatial modulation elements is constituted by a micromirror device in which a large number of micromirrors each capable of changing an angle of a reflecting surface according to a control signal are arranged on a substrate in a two-dimensional manner. Exposure head. A grating in which the spatial modulation element is configured by arranging in parallel a plurality of movable gratings each having a ribbon-like reflecting surface and movable according to a control signal, and fixed gratings having a ribbon-like reflecting surface. The exposure head according to claim 13, comprising a light valve. The microlens array provided with the microlens provided corresponding to each pixel part of the said spatial modulation element, and condensing a laser beam for every pixel is arrange | positioned on the output side of the said spatial modulation element. The exposure head according to any one of 15. Between the laser device and the spatial modulation element,
A collimator lens for converting the light beam from the laser device into a parallel light beam;
The light flux width at each exit position is changed so that the ratio of the light flux width at the peripheral portion to the light flux width at the central portion close to the optical axis is smaller on the exit side than on the entrance side, and the collimator lens changes the parallel light flux. A light amount distribution correction optical system that corrects the light amount distribution of the laser light that has been made to be substantially uniform on the irradiated surface of the spatial modulation element;
The exposure head according to claim 13, wherein the exposure head is disposed. An exposure apparatus comprising: the exposure head according to any one of claims 13 to 17; and a moving unit that moves the exposure head relative to an exposure surface.

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