JP3886619B2 - Object defect inspection method and inspection apparatus - Google Patents

Description

となり、
系全体としての焦点距離Ｆは、
【００２２】
【数２】

となり、
倍率ｍは、
【００２３】
【数３】

となる。なお、焦点距離Ｆは、前側主点から第１凸レンズ６２の前方方向（または、後側主点から第２凸レンズ６５の後方方向）への距離である。
【００２４】
かかる構成において、開口絞り６３は、第１凸レンズ６２と第２凸レンズ６５との間において第１凸レンズ６２の後方焦点面に配置され、第１凸レンズ６２で集光された光のうちの直接光または散乱光のいずれかを選択的に遮蔽する。直接光を遮蔽したときにスクリーン３０に形成される像は暗視野像であり、微妙な色ムラの検出に適している。また、散乱光を遮蔽したときにスクリーン３０に形成される像は明視野像であり、傷、ゴミ、ピンホールといった比較的識別の容易な欠陥の検出に適している。明視野像と暗視野像の切り替えは、開口絞り６３の移動により達成できる。開口絞り６３の中央開口部６６が図１に示すように光軸６７上にある場合には明視野像が形成され、この開口絞り６３を光軸６７と垂直な方向にずらすことにより開口部６６を光軸６７から逸脱させると暗視野像が形成される。
【００２５】
したがって、一般的な検査手順は、カラーフィルタの欠陥が最も観察し易くなるように上記公式（１）（３）にしたがってパラメータを選べばよい。しかし、迅速かつ精度の高い検査のためには明るい像を得る必要があり、そのためには、系のサイズをコンパクトにすることが重要である。
【００２６】
この配置の場合の系のサイズＬ、すなわち、カラーフィルタ８１からスクリーン３０までの距離Ｌは、
Ｌ＝ａ＋ｂ＋ｔ …（４）
で与えられる。そして、ｔとｆ１およびｆ２との間に特別な制約がないとしたときの一般的最小サイズＬ₀はつぎの式（５）で与えられ、倍率ｍ₀＝１である。
【００２７】
【数４】

このときのａ₀およびｂ₀は、それぞれつぎの式（６）および式（７）で与えられる。
【００２８】
【数５】

【００２９】
【数６】

上記の式（５）から、一般的最小サイズＬ₀は、第１凸レンズ６２と第２凸レンズ６５との間の距離ｔの関数である。
【００３０】
一方、開口絞り（空間絞り）６３は、第１凸レンズ６２と第２凸レンズ６５との間になければならないこと、およびａ₀＞０、ｂ₀＞０でなければならないことから、つぎの条件が成り立つ。
【００３１】
ｆ１＞ｆ２のとき、２・ｆ２＞ｔ≧ｆ１ …（８）
ｆ２＞ｆ１のとき、２・ｆ１＞ｔ≧ｆ１ …（９）
そこで、式（５）のＬ₀は、ｔ＝ｆ１のとき一つの極小値をとることがわかる。このときのＬ₀は、
【００３２】
【数７】

である。このようにして、最もコンパクトな系の一つは、ｔ＝ｆ１、すなわち、図２に示すように、第２凸レンズ６５を開口絞り６３と密着させて第１凸レンズ６２の後方焦点面上に配置させる構成であることがわかる。この構成は系のサイズを最小とし得ることに加えて、つぎのようなメリットも有する。
【００３３】
すなわち、カラーフィルタ８１を透過もしくは反射した光は、第１凸レンズ６２により、その後方焦点面に集光されるが、開口絞り６３および第２凸レンズ６５がちょうどこの焦点面上に設置され、開口絞り６３と第２凸レンズ６５との間隔が実質的に零であるため、光がほとんどロスすることなく結像に寄与することになり、きわめて明るい像が得られる。
【００３４】
第１凸レンズ６２の後方焦点面上には検査物体のフーリエ変換像が現れ、開口絞り６３により任意の散乱光（回折光）若しくは直接光（０次散乱光）を選択して像を形成させるものであるが、開口絞り６３と第２凸レンズ６５を一体化できるのでどの光を選んでも像が逃げることがないという使用上のメリットもあることが判明した。図１に示す一般的な構成・配置では、開口絞り６３によって選ぶ光を代えるたびに、第２凸レンズ６５の位置を調整する必要がある。
【００３５】
このように、ｔ＝ｆ１の構成は、系をコンパクトにできることに加え、得られる像が大変鮮明でその上検査の操作が容易であるという利点をもち、カラーフィルタの欠陥検査手法として極めて好ましい。
【００３６】
つぎに、ｔ＝ｆ１という条件のもとで、第２凸レンズ６５の焦点距離ｆ２と系の大きさとの関係について検討する。
【００３７】
既に述べたように、ｔ＝ｆ１のときの系の一般的最小サイズは、（１０）式で与えられる。一方、（８）式に示すように、ｆ１とｆ２の間にはｆ２≧ｆ１／２という関係があるので、この条件下でのＬ₀の最小値は、ｆ２＝ｆ１／２のときである。
【００３８】
なお、ｔ＝ｆ１＝２・ｆ２のときの結像公式は、
ｂ＝ｆ１²／（ａ＋ｆ１） …（１１）
となり、像倍率は、
ｍ＝ｆ１／（ａ＋ｆ１） …（１２）
となる。
【００３９】
これらの式から、ｔ＝ｆ１＝２・ｆ２のときには、カラーフィルタ８１は、第１凸レンズ６２前方の任意の位置に置くことができることが判る。また、ａ＝０のとき、すなわち、カラーフィルタ８１を第１凸レンズ６２に接するように配置したとき、最大像倍率が得られ、カラーフィルタ８１を第１凸レンズ６２から離すにしたがって像は単調に小さくなる。
【００４０】
また、ｔ＝ｆ１＝２・ｆ２という構成においてａ＝０とすると、系のサイズを２ｆ１（＝２ｔ）と非常にコンパクトにでき、その上、カラーフィルタ８１と第１凸レンズ６２が密着しているため、散乱光のロスが全くなく極めて明るい像が得られる。ただし、この場合には、透過法には適用できるが反射法には使えない。
【００４１】
さて、ｔ＝ｆ１の構成において、第１凸レンズ６２の焦点距離ｆ１と第２凸レンズ６５の焦点距離ｆ２とを等しくすれば、第１凸レンズ６２と第２凸レンズ６５に対して同一形状、同一材質のレンズを用いることができる。したがって、ｔ＝ｆ１＝ｆ２＝ｆという構成にすれば、安価に光学装置６０を製作できるという利点がある。
【００４２】
ｔ＝ｆ１＝ｆ２＝ｆのときの結像公式は、
ｂ＝ｆ²／ａ …（１３）
と、きわめて簡単な式に帰着される。したがって、カラーフィルタおよびスクリーンの位置を簡単に求めることができ作業が容易になることに加え、ｔ＝ｆ１の特徴として既に述べたように、ａは０および負以外の任意の値をとりうる。すなわち、カラーフィルタ８１は第１凸レンズ６２の前方の任意の位置に置くことができるというメリットをもつ。このことは、結像光学手段が一個の場合には被検体の位置に禁制領域があることと対照的である。
【００４３】
この構成における系の最小サイズＬ₀は、
Ｌ₀＝３ｆ、ａ₀＝ｆ、ｂ₀＝ｆ
である。
【００４４】
すなわち、ｔ＝ｆ１＝ｆ２＝ｆの構成において、カラーフィルタ８１を第１凸レンズ６２の前方焦点位置に置くと、像は第２凸レンズ６５の後方焦点位置に結像され、系のサイズは３ｆになることがわかる。このことは、光学装置６０としてフーリエ変換レンズを用いた場合と比較して、その系の大きさを３／４にできることを示すものである。
【００４５】
ここで、参考のためにフーリエ変換レンズについて説明する。本実施形態の光学装置６０と類似のレンズ構成をもつものとして、図３に示すような構成のフーリエ変換レンズがある。フーリエ変換レンズというのは、焦点距離ｆの２枚の凸レンズ１６２、１６５を２ｆの距離をおいて対向させ、両レンズ間の中央に空間フィルタ１６３を配置した構成を有し、前側凸レンズの前側焦点面に物体たとえばカラーフィルタ８１をおき、後側凸レンズの後側焦点面のスクリーン３０に像を形成するものである。
【００４６】
このフーリエ変換レンズの場合は、系の焦点距離が無限大である点で、本実施形態の光学装置６０とは相違する。すなわち、本実施形態の光学装置６０はあくまでも実像を形成するための光学装置であり、系の焦点距離が有限となるように、具体的には、レンズ間距離ｔが両レンズの焦点距離の和（ｆ１＋ｆ２）とは異なる値となるように設計されている。
【００４７】
また、フーリエ変換レンズの場合には、系の大きさ、すなわち、物体から像までの距離Ｌが４ｆに固定されてしまうが、本実施形態の光学装置６０の場合は系の大きさを自由に設計することができる。しかも、フーリエ変換レンズの場合と同じように２つのレンズに対して同じ焦点距離のものを用いた場合、すなわちｆ１＝ｆ２＝ｆとした場合でも、系のサイズＬをＬ＝３ｆまで小さくすることができることは上述したとおりである。
【００４８】
つぎに、図１に示す一般的な構成を基本とし、レンズ間距離ｔと第２凸レンズ６５の焦点距離ｆ２との関係に着目して系のサイズを考えてみる。
【００４９】
まず、上述した式（１）において、ｔ＝ｆ２とすると、結像公式は、
【００５０】
【数８】

となり、倍率は、
【００５１】
【数９】

となる。
【００５２】
つまり、倍率はカラーフィルタ８１の位置および第２凸レンズ６５の焦点距離ｆ２のみの関数であり、第１凸レンズ６２の焦点距離ｆ１に依存しない。
【００５３】
この系において最小サイズを得るための式は、一般式における最小サイズの式（５）にｔ＝ｆ２を代入することにより得られ、
【００５４】
【数１０】

となる。一方、像が実像であること、および、開口絞り６３が両レンズ間にあることから、
ｆ２≧ｆ１≧ｆ２／２ …（１７）
である。この条件下で式（１６）のＬ₀を最小するのは、
ｆ１＝ｆ２／２ …（１８）
のときである。すなわち、ｆ２＝ｔ、ｆ１＝ｆ２／２の場合も、系をコンパクトに小さくできるという観点から好適な配置である。
【００５５】
このときの結像公式は、
ｂ＝ｆ２（ｆ２−ａ）／ａ …（１９）
であり、像倍率は、
ｍ＝ｆ２／ａ …（２０）
である。式（１９）からａ≦ｆ２でなければならない。そして、式（２０）から倍率はａ＝ｆ２のとき最小であり、カラーフィルタ８１をレンズに近づけるにしたがって単調に増加する。
【００５６】
ｆ２＝ｔであり、且つ、式（１８）を満たす構成において、系を最小にする条件は、ａ＝ｆ２であり、このときのＬ₀は２・ｆ２（＝２ｔ）であり、ｂは、式（１９）からｂ＝０となる。
【００５７】
この配置は、系のサイズが２・ｆ２と極めてコンパクトであることに加え、ｂ＝０、すなわち、第２凸レンズ６５とスクリーン３０とが密着しているので、透過型スクリーンで像を観察するのに好適である。しかも、透過法にも反射法にも用いることができる。
【００５８】
以上、図１または図２と共に説明してきた光学装置６０を用いたカラーフィルタの欠陥の検査装置の構成図を図４に示す。この検査装置は、平行光源を使用し、検査対象物体であるカラーフィルタの透過光を観察するものである。なお、本実施形態においてカラーフィルタとは、基板上に、例えばＲＧＢ（Ｒｅｄ、Ｇｒｅｅｎ、Ｂｌｕｅ）などの着色層の少なくとも一色を持つ色フィルタをいい、この基本的な構成に保護層や電極層が付加させたものも包含される。具体的には、例えば、透明基板の上にＲ、Ｇ、Ｂ、の少なくとも一色の層が形成されたもの、同基板上にブラックマトリクスが形成され、その間にＲＧＢカラーフィルタ層が形成されたもの、更にその上に必要に応じてオーバーコート層が設けられたもの、更に、次いでその上に透明電極が形成されているもの、およびそれらの構成を基本として更に付加的な層を有するものをいう。
【００５９】
また、カラーフィルタの製造方法として、染色法、顔料分散法、印刷法、および電着法があるが、いずれの製造方法によって製造されたカラーフィルタについても本発明の検査方法および検出装置は適用可能である。また、カラーフィルタの製造における各工程の中間製品および最終製品についても本発明の検査方法および検査装置は適用可能である。
【００６０】
図４に示すように、この装置は、（ａ）検査対象であるカラーフィルタ８１に照射する検査光Ｌ２１を出力する平行光源１２と、（ｂ）カラーフィルタ８１を保持するとともに、検査光Ｌ２１の光軸とカラーフィルタ８１の受光面との成す角を変化させる入射角可変保持器２０と、（ｃ）検査光Ｌ２１の照射の結果カラーフィルタ８１を透過する光Ｌ２３を集光し、投影光Ｌ２５として出射することにより、カラーフィルタ８１の像を像空間に形成する光学装置６０と、（ｄ）光学装置６０による像をその表面において結像させる投影スクリーン３０と、（ｅ）投影スクリーン３０に投影された投影光Ｌ２５の投影像を撮像する撮像器４０と、（ｆ）撮像器４０による撮像結果を収集し表示するとともに、入射角可変保持器２０に検査光Ｌ２１の光軸とカラーフィルタ８１の受光面との成す角を指示し、さらに、光学装置６０の鏡筒６１の位置を鏡筒保持器６４に指示する処理部５０とを備える。
【００６１】
すでに、その基本構成を詳しく説明したように、光学装置６０は凸レンズ６２、６５と、両レンズ間に設けられた開口絞り６３とを備えている。そして、これらの各光学要素は鏡筒６１により所定の位置関係を保って支持されている。この鏡筒６１は鏡筒保持器６４によって検査光Ｌ２１がカラーフィルタ８１を透過した光の光軸（検査光Ｌ２１の光軸と一致している）に略垂直な移動面に沿って移動可能に保持されている。鏡筒６１の前記移動面上の位置は、上述したように処理部５０から鏡筒保持器６４に与えられる指示に基づいて決定される。
【００６２】
平行光源１２は、高圧水銀ランプやキセノンランプ等の高輝度の点光源１１と、この点光源１１から出力された光を平行化するコリメートレンズ系１３を備えているものであるが、これに代えて、反射鏡等を用いて太陽光線を利用するものでもよい。
【００６３】
平行光源１２から出力される検査光は、単色光でも白色光でもよく、それぞれに利点がある。白色光は検査対象物体が本実施形態のようにカラーフィルタの場合には、Ｒ、Ｇ、Ｂの各々の画素をそのカラーで観察することができるという利点や、色ムラの原因がＲ、Ｇ、Ｂのいずれに基づくものかを解析することができるという利点がある。また、色ムラによっては単色光を用いた方が鮮明に現れる場合も多い。
【００６４】
このように構成された本実施形態の装置は、以下のようにしてカラーフィルタの欠陥の検査方法を実行する。
【００６５】
まず、処理部５０がカラーフィルタ８１を保持した入射角可変保持器２０に指示して、検査光の光軸とカラーフィルタ８１の検査光の受光面とが所定の角度で交差（例えば、直交）するように設定する。
【００６６】
この状態で、平行光源１２から出力された検査光Ｌ２１をカラーフィルタ８１に照射する。検査光Ｌ２１の照射に応じてカラーフィルタ８１を透過した透過光Ｌ２３は、光学装置６０により集光され、投影光Ｌ２５として投影スクリーン３０に到達する。この際、開口絞り６３により散乱光を遮蔽した場合は、直接光のみによって像が形成され（明視野像）、直接光を遮蔽した場合は、散乱光によって像が形成される（暗視野像）。
【００６７】
投影スクリーン３０はカラーフィルタ８１の像が最も鮮明になる位置に設置されている。この投影像は、カラーフィルタ８１の状態、すなわち、色調の異常などの欠陥を反映しているとともに、干渉縞の発生や光源像によるムラが低減されている。特に、カラーフィルタ８１表面で発散する光を光学装置６０により像面に集光されるため、光学装置６０を用いない場合に比べて投影像が鮮明に映し出されるため、微小な異物や傷等の欠陥を高感度に検出することができる。
【００６８】
こうして、投影スクリーン３０に投影された投影像を、撮像器４０が撮像し、撮像結果を処理部５０が収集する。処理部５０は、収集した撮像結果に基づいた画像処理結果を表示するとともに、必要に応じて、撮像結果や処理結果の格納あるいは印刷を行う。
【００６９】
そして、処理部５０による表示結果、格納結果、または印刷結果に基づいてカラーフィルタ８１の欠陥を検出する。投影スクリーン３０に投影された投影像では、干渉縞の発生や光源像によるムラが低減されているので、微妙な色調の異常などの欠陥の判別が可能となる。
【００７０】
なお、この実施形態では物体を透過した光で像を形成しているが、物体に光を照射し、その反射光で像を形成しても良い。
【００７１】
カラーフィルタ８１の面積が大きい場合には、検査光Ｌ２１が略平行光であることを考え合わせると、光学装置６０では、カラーフィルタ８１の一部分しか投影スクリーン３０に映し出すことができない。そこで、この実施形態では、光学装置６０の鏡筒６１が、透過光Ｌ２３の光軸と略垂直な面において平行移動できるようになっている。
【００７２】
鏡筒６１の平行移動は鏡筒保持器６４が処理部５０からの指示を受けて達成される。すなわち、鏡筒保持器６４は鏡筒６１が透過光Ｌ２３の光軸と略垂直な面において平行移動できるよう機構を備えており、この平行移動機構により鏡筒６１を主走査および副走査することにより結果としてカラーフィルタ８１の全面を投影スクリーン３０上に映し出すことができる。
【００７３】
本実施形態では鏡筒６１を平行移動させているが、これに代えてカラーフィルタ８１を検査光Ｌ２１の光軸と略垂直な面において平行移動させてもよい。
【００７４】
また、本実施形態では撮像器４０を用いているが、これに代えて、目視によって投影スクリーン３０上の投影像を観察して、カラーフィルタ８１の欠陥を検出することも可能である。この場合にも、投影スクリーン３０に投影された投影像では、干渉縞の発生や光源像によるムラが低減されているので、微妙な色調の異常などの欠陥の判別が可能となる。
【００７５】
次に、上述した検査動作が実行されても、投影像内の光強度変化が緩やかで、欠陥の有無がはっきりとしない場合がある。
【００７６】
こうした場合には、処理部５０から入射角可変保持部２０へ、検査光Ｌ２１の光軸とカラーフィルタ８１の検査光Ｌ２１の受光面との成す角度の変更を指示する。角度の変更後または角度を変更しつつ、再度、上記と同様にして、検査光Ｌ２１をカラーフィルタ８１に照射し、カラーフィルタ８１を透過した透過光Ｌ２３を投影スクリーンに投影して投影像を観察する。前回の観察のときと略同一の光強度変化が短い像内距離で発生した投影像や、厚みにムラのある層中における厚みのムラに伴う光路長の差を変化させた投影像を観察することになるので、精度よく欠陥を検査できる。
【００７７】
光学装置６０の第１凸レンズ６２および第２凸レンズ６５はいずれも１枚レンズであるが、凸レンズの機能をもった組み合わせレンズや球面ミラーなどのように、光を収束させることのできるものであれば他の結像光学手段であってもよい。
【００７８】
また、開口絞り６３は、第１凸レンズ６２の後方焦点面上において通過する光を選択することにより像のコントラストを高めるものである。したがって、この目的にかなうものであれば、いかなる形状のものでも構わない。たとえば、耐熱性のシートに穴をあけ、その中心に直接光のみをカットする小さな円板を設けるとか、同心円状に散乱光のみを通す溝をあけたもの等がある。本発明者らは、最も単純に、耐熱性シートに直径５ｍｍ程度の穴をあけ、この耐熱性シートを光軸と垂直な方向に移動させることにより所望の光を選択して、好結果を得ている。また、開口絞り６３の光軸上の位置は、第１凸レンズ６２と第２凸レンズ６５との間になければならないことは既に述べたとおりであり、レンズ間距離ｔと第１凸レンズ６２の焦点距離ｆ１との間にはｔ≧ｆ１の関係がある。
【００７９】
最後に、本発明の欠陥検査方法により得られた像を撮影した写真を図５〜図７に示す。
【００８０】
図５は、ハードコートＰＭＭＡ板に対して５８９ｎｍの波長の光を照射し、その反射光を光学装置６０で集光したときにスクリーン３０に形成された像を示すものであり、開口絞り６３の調整により明視野像としている。なお、中央の大きな円は注目箇所を示すためにハードコートＰＭＭＡ板上に予め描いたものであり、欠陥ではない。このときの光学装置６０に関する条件は次の通りである。第１および第２凸レンズの焦点距離ｆ１およびｆ２がそれぞれ２５ｃｍ、レンズ間距離ｔが２５ｃｍ、物体と第１凸レンズとの距離ａが１２ｃｍ、第２凸レンズまたは開口絞りとスクリーンとの距離ｂが５２ｃｍである。
【００８１】
図６はＳＴＮタイプのカラーフィルタに検査光を照射し、その透過光を光学装置６０で集光して暗視野像をスクリーン３０上に形成したときの写真である。中央部に色ムラが現れていることがわかる。この実施例の場合も、図５と場合と同様にｆ１＝ｆ２＝ｔ＝２５ｃｍ、ａ＝１２ｃｍ、ｂ＝５２ｃｍである。
【００８２】
図７はＴＦＴタイプのカラーフィルタに検査光を照射し、その反射光を光学装置６０で集光して暗視野像をスクリーン３０上に形成したときの写真である。中央部にある黒い点は、表面にスピンコートを行った際の回転中心部に現れるいわゆる「へそムラ」である。これが暗視野像として鮮明に現れていることが判る。この実施例の場合も、図５と場合と同様にｆ１＝ｆ２＝ｔ＝２５ｃｍ、ａ＝１２ｃｍ、ｂ＝５２ｃｍである。
【００８３】
【発明の効果】
以上説明したように、本発明の物体の欠陥検査方法および欠陥検査装置を用いると、目視では困難であった微妙な色調異常や傷などが鮮明に現れるため迅速且つ安定的に物体の欠陥を検査することができる。
【図面の簡単な説明】
【図１】本発明の一実施形態である物体の欠陥検査装置に用いる光学装置６０の基本構成を示す配置図。
【図２】光学装置６０の好適な配置を示す図。
【図３】従来のフーリエ変換レンズの構成を示す図。
【図４】本発明の一実施形態である物体の欠陥検査装置を示す構成図。
【図５】この実施形態の装置を用いて形成された像を写した写真。
【図６】この実施形態の装置を用いて形成された像を写した写真。
【図７】この実施形態の装置を用いて形成された像を写した写真。
【符号の説明】
１１…点光源、１２…平行光源、２０…入射角可変保持器、３０…投影スクリーン、４０…撮像器、５０…処理部、６０…光学装置、６１…鏡筒、６２…第１凸レンズ、６３…開口絞り、６５…第２凸レンズ、８１…カラーフィルタ。[0001]
BACKGROUND OF THE INVENTION
The present invention is for various optical materials such as color filters, optical MMA plates (antistatic hard coat MMA (methyl methacrylate) plates, MMA opal plates, etc.), optical functional films (polarizing films, retardation films, etc.), etc. The present invention relates to an object defect inspection method and a defect inspection apparatus.
[0002]
[Prior art]
The optical material object is desired to have as few defects as possible, such as scratches, dust, foreign matter, irregularities, and pinholes on the surface or inside, because of the required optical properties. In particular, a color filter for a liquid crystal display device is required to have these optical defects removed in order to form a high-definition and beautiful image. Therefore, in order to stably manufacture the color filter, high-sensitivity and rapid product inspection is required in addition to advanced manufacturing techniques.
[0003]
By the way, since the abnormal color tone caused by the abnormal shape of the pixel of the color filter or the uneven thickness of the pigment is very delicate, it has been difficult to implement this detection as a device. Therefore, a method in which a skilled inspector directly visually observes a color filter under a specific wavelength of light in a dark room has been generally adopted at a manufacturing site.
[0004]
On the other hand, the color filter is irradiated with light emitted from the light source, the transmitted light or reflected light is observed with a CCD camera, image processing is performed as necessary, and a color filter defect is detected. Have been proposed (JP-A-6-208017, JP-A-6-94638).
[0005]
As a method of inspecting defects such as striae and enormous parts in specimens such as films, parallel light is incident on the specimen and the transmitted or reflected light is projected onto the screen, and the bright and dark parts in the formed projection image are displayed. An observation method is known (Japanese Patent Publication No. 61-68543).
[0006]
[Problems to be solved by the invention]
However, according to the former method, since the light source image is observed through the color filter, the brightness unevenness is large, and it is difficult to detect a subtle color tone abnormality.
[0007]
Also in the latter method, according to the results of the study by the present inventors, it has been difficult to visualize defects such as subtle color unevenness, scratches, and dirt.
[0008]
[Means for Solving the Problems]
The object defect inspection method of the present invention has been made in view of such problems, and irradiates an inspection target object with an inspection light, and uses an optical device to transmit light reflected or reflected from the object. In this method, an image of an object is formed by focusing and the defect of the object is inspected by observing the image. The optical device is a first method for collecting light transmitted through or reflected by an object. An imaging optical unit, an aperture stop disposed at a rear focal plane of the first imaging optical unit, and shielding either scattered light or direct light of light transmitted through or reflected by an object, and the aperture stop And a second imaging optical means that images scattered light or direct light that has passed through the aperture stop and has a focal length F of finite. The distance t between the first imaging optical means and the second imaging optical means is equal to the focal length f1 of the first imaging optical means (or the first imaging optical means and the second imaging optical means; Is equal to the focal length f2 of the second imaging optical means). Features.
[0009]
The object defect inspection apparatus according to the present invention includes a light source that outputs inspection light for irradiating an object to be inspected, and an optical device that forms an image of the object by condensing light transmitted through or reflected by the object. The optical apparatus includes: first imaging optical means for collecting light transmitted through or reflected by the object; and light transmitted through the object disposed at a rear focal plane of the first imaging optical means, or An aperture stop that shields either scattered light or direct light of the reflected light; and second imaging optical means that is disposed behind the aperture stop and forms an image of the scattered light or direct light that has passed through the aperture stop; With a finite focal length F Yes, the focal length f1 of the first imaging optical means is equal to the distance t between the first imaging optical means and the second imaging optical means (or the first imaging optical means and the second imaging optical means) Is equal to the focal length f2 of the second imaging optical means) It is characterized by.
[0010]
A Fourier transform image of the object is formed on the rear focal plane of the first imaging optical means. If the structure that causes light scattering is irregular, such as dust, foreign matter, or scratches on the object, the Fourier transform image has a monotonically decreasing intensity distribution with the center at the maximum, and the structure that causes light scattering is regular. In some cases, a diffraction pattern corresponding to the structure appears. A color filter as an inspection object is an example of the latter. In any case, in the Fourier transform image of the object, an intensity maximum based on direct light (zeroth-order scattered light) appears at the center thereof, and an intensity distribution based on scattered light appears around it.
[0011]
The aperture stop selects light contributing to an image formed behind the second imaging optical means by blocking a part of the Fourier transform image. An image formed by including direct light passing through the center of the Fourier transform image is called a bright field image, and an image made only of scattered light is called a dark field image, but by adjusting the aperture range of the aperture stop, Switching between a field image and a dark field image is possible.
[0012]
By using the method or apparatus of the present invention, an image with reduced interference fringes and unevenness due to the light source image is formed in the image space behind the optical device. Appears in the image. In particular, observation with a bright-field image is suitable for defect inspections such as scratches, dust, and pinholes that are relatively easy to identify, and observation of a dark-field image is suitable for detecting subtle color unevenness.
[0013]
The first imaging optical means in the present invention may be anything as long as it converges light. A typical first imaging optical means is a convex lens or a combination lens having the function of a convex lens, but may be a spherical mirror, a Fresnel lens, or the like. The second imaging optical means is for forming an image with light that has passed through the aperture stop, and a general example thereof is a convex lens. In the embodiments described later, description will be made using convex lenses as the first and second imaging optical means.
[0014]
In order for the inspection light to be highly condensed by the first imaging optical means, it is preferable to use substantially parallel light. The substantially parallel light is obtained, for example, by collimating diverging light that radiates from a predetermined point using an optical system such as a lens.
[0015]
The aperture stop (spatial filter) is for increasing the contrast of the image by selecting light passing through the rear focal plane of the first imaging optical means. Therefore, any shape can be used as long as it meets this purpose. For example, there is a hole in the heat-resistant sheet and a small disk that cuts only light directly in the center, or a concentric circular groove that allows only scattered light to pass through. Most simply, a hole having a diameter of about 5 mm is formed in the heat-resistant sheet, and the desired light is selected by moving the heat-resistant sheet, and good results are obtained.
[0016]
Further, the position of the aperture stop on the optical axis must be between the first image forming optical means and the second image forming optical means from the request of the present invention. That is, t ≧ f1 where t is the distance between the first imaging optical means and the second imaging optical means, and f1 is the rear focal length when a convex lens is used as the first imaging optical means.
[0017]
As an image observation method, there are a method in which an image is once projected on a screen and a method in which the image is directly observed with a CCD camera or the like. In the former case, there are a reflective screen and a transmissive screen. Reflective screens include, for example, whiteboards, etc. This method provides the brightest and clearest image in addition to simplicity, and is optimal for defect inspection, but it must be observed from a direction inclined from the optical axis. There is a drawback that the image is distorted. Translucent screens do not have this drawback, but seem to reduce sharpness and brightness. The direct observation method using a CCD camera has no image distortion and is sufficiently bright and clear. However, in addition to requiring an expensive CCD and a display device, some techniques are required for adjusting the optical system. In the case of a CCD camera, a lens (having a function of forming an image on the CCD light receiving surface) provided on the front surface of the camera can be used as the second imaging optical means.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an object defect inspection method and an object defect inspection apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings when a color filter is used as an object to be inspected.
[0019]
First, the basic configuration of the optical apparatus used in the defect inspection method and the defect inspection apparatus according to the present embodiment will be described with reference to FIG. The optical device 60 includes a first convex lens 62 as a first imaging optical means, a second convex lens 65 as a second imaging optical means, and an aperture stop 63 disposed between both lenses.
[0020]
The focal length of the first convex lens 62 is f1, the focal length of the second convex lens 65 is f2, the distance between the first convex lens 62 and the second convex lens 65 is t, and the distance between the color filter 81 to be observed and the first convex lens 62. Is a, and the distance between the second convex lens 65 and the screen 30 is b, the imaging formula for the entire system is
[0021]
[Expression 1]

And
The focal length F of the entire system is
[0022]
[Expression 2]

And
The magnification m is
[0023]
[Equation 3]

It becomes. The focal length F is a distance from the front principal point to the front direction of the first convex lens 62 (or from the rear principal point to the rear direction of the second convex lens 65).
[0024]
In such a configuration, the aperture stop 63 is disposed on the rear focal plane of the first convex lens 62 between the first convex lens 62 and the second convex lens 65, and direct light of the light collected by the first convex lens 62 or Selectively block any of the scattered light. The image formed on the screen 30 when direct light is shielded is a dark field image, which is suitable for detecting subtle color unevenness. The image formed on the screen 30 when the scattered light is shielded is a bright-field image, which is suitable for detecting defects that are relatively easy to identify, such as scratches, dust, and pinholes. Switching between the bright field image and the dark field image can be achieved by moving the aperture stop 63. When the central aperture 66 of the aperture stop 63 is on the optical axis 67 as shown in FIG. 1, a bright field image is formed, and the aperture 66 is shifted by shifting the aperture stop 63 in a direction perpendicular to the optical axis 67. Is deviated from the optical axis 67, a dark field image is formed.
[0025]
Therefore, in a general inspection procedure, the parameters may be selected according to the above formulas (1) and (3) so that the color filter defect is most easily observed. However, it is necessary to obtain a bright image for quick and high-precision inspection. For this purpose, it is important to make the system size compact.
[0026]
The size L of the system in this arrangement, that is, the distance L from the color filter 81 to the screen 30 is
L = a + b + t (4)
Given in. The general minimum size L when there is no special constraint between t and f1 and f2. ₀ Is given by the following equation (5), and the magnification m ₀ = 1.
[0027]
[Expression 4]

A at this time ₀ And b ₀ Are given by the following equations (6) and (7), respectively.
[0028]
[Equation 5]

[0029]
[Formula 6]

From equation (5) above, the general minimum size L ₀ Is a function of the distance t between the first convex lens 62 and the second convex lens 65.
[0030]
On the other hand, the aperture stop (space stop) 63 must be between the first convex lens 62 and the second convex lens 65, and a ₀ > 0, b ₀ Since it must be> 0, the following condition holds.
[0031]
When f1> f2, 2 · f2> t ≧ f1 (8)
When f2> f1, 2 · f1> t ≧ f1 (9)
Therefore, L in equation (5) ₀ It can be seen that when t = f1, it takes one minimum value. L at this time ₀ Is
[0032]
[Expression 7]

It is. Thus, one of the most compact systems is t = f1, that is, as shown in FIG. 2, the second convex lens 65 is placed on the rear focal plane of the first convex lens 62 in close contact with the aperture stop 63. It turns out that it is the composition to make it. In addition to minimizing the size of the system, this configuration has the following advantages.
[0033]
That is, the light transmitted or reflected by the color filter 81 is condensed on the rear focal plane by the first convex lens 62, but the aperture stop 63 and the second convex lens 65 are installed just on this focal plane. Since the distance between the third convex lens 65 and the second convex lens 65 is substantially zero, the light contributes to the image formation with almost no loss, and an extremely bright image is obtained.
[0034]
A Fourier transform image of the inspection object appears on the rear focal plane of the first convex lens 62, and an arbitrary aperture is selected from the scattered light (diffracted light) or direct light (0th order scattered light) by the aperture stop 63 to form an image. However, since the aperture stop 63 and the second convex lens 65 can be integrated, it has been found that there is a merit in use that an image does not escape even if any light is selected. In the general configuration and arrangement shown in FIG. 1, it is necessary to adjust the position of the second convex lens 65 every time the light selected by the aperture stop 63 is changed.
[0035]
As described above, the configuration of t = f1 has the advantage that the system can be made compact and the obtained image is very clear and the inspection operation is easy, and is very preferable as a defect inspection method for the color filter.
[0036]
Next, the relationship between the focal length f2 of the second convex lens 65 and the size of the system will be examined under the condition t = f1.
[0037]
As already described, the general minimum size of the system when t = f1 is given by equation (10). On the other hand, as shown in the equation (8), there is a relationship of f2 ≧ f1 / 2 between f1 and f2, and therefore L under this condition ₀ The minimum value is when f2 = f1 / 2.
[0038]
The imaging formula when t = f1 = 2 · f2 is
b = f1 ² / (A + f1) (11)
And the image magnification is
m = f1 / (a + f1) (12)
It becomes.
[0039]
From these expressions, it can be seen that when t = f1 = 2 · f2, the color filter 81 can be placed at an arbitrary position in front of the first convex lens 62. When a = 0, that is, when the color filter 81 is arranged so as to be in contact with the first convex lens 62, the maximum image magnification is obtained, and as the color filter 81 is moved away from the first convex lens 62, the image monotonously decreases. Become.
[0040]
Further, if a = 0 in the configuration of t = f1 = 2 · f2, the system size can be made very compact as 2f1 (= 2t), and the color filter 81 and the first convex lens 62 are in close contact with each other. Therefore, an extremely bright image can be obtained without any loss of scattered light. However, in this case, it can be applied to the transmission method but not to the reflection method.
[0041]
In the configuration of t = f1, if the focal length f1 of the first convex lens 62 and the focal length f2 of the second convex lens 65 are equal, the first convex lens 62 and the second convex lens 65 have the same shape and the same material. A lens can be used. Therefore, if t = f1 = f2 = f, the optical device 60 can be manufactured at low cost.
[0042]
The imaging formula when t = f1 = f2 = f is
b = f ² / A (13)
And it is reduced to a very simple formula. Therefore, the position of the color filter and the screen can be easily obtained and the operation is facilitated. In addition, as already described as the feature of t = f1, a can take any value other than 0 and negative. That is, the color filter 81 has an advantage that it can be placed at an arbitrary position in front of the first convex lens 62. This is in contrast to the fact that there is a forbidden region at the position of the subject when there is one imaging optical means.
[0043]
Minimum system size L in this configuration ₀ Is
L ₀ = 3f, a ₀ = F, b ₀ = F
It is.
[0044]
That is, in the configuration of t = f1 = f2 = f, when the color filter 81 is placed at the front focal position of the first convex lens 62, the image is formed at the rear focal position of the second convex lens 65, and the system size is 3f. I understand that This indicates that the size of the system can be reduced to ¾ compared to the case where a Fourier transform lens is used as the optical device 60.
[0045]
Here, a Fourier transform lens will be described for reference. A lens having a lens configuration similar to that of the optical device 60 of this embodiment is a Fourier transform lens having a configuration as shown in FIG. The Fourier transform lens has a configuration in which two convex lenses 162 and 165 having a focal length f are opposed to each other with a distance of 2f, and a spatial filter 163 is arranged at the center between both lenses, and the front focal point of the front convex lens. An object such as a color filter 81 is placed on the surface, and an image is formed on the screen 30 on the rear focal plane of the rear convex lens.
[0046]
This Fourier transform lens is different from the optical device 60 of this embodiment in that the focal length of the system is infinite. That is, the optical device 60 of this embodiment is an optical device for forming a real image to the last, and specifically, the inter-lens distance t is the sum of the focal lengths of both lenses so that the focal length of the system is finite. It is designed to have a value different from (f1 + f2).
[0047]
In the case of a Fourier transform lens, the size of the system, that is, the distance L from the object to the image is fixed to 4f. However, in the case of the optical device 60 of this embodiment, the size of the system can be freely set. Can be designed. Moreover, even when two lenses having the same focal length are used as in the case of the Fourier transform lens, that is, when f1 = f2 = f, the system size L is reduced to L = 3f. As described above, this can be done.
[0048]
Next, based on the general configuration shown in FIG. 1, let us consider the size of the system by focusing on the relationship between the inter-lens distance t and the focal length f2 of the second convex lens 65.
[0049]
First, in the above equation (1), when t = f2, the imaging formula is
[0050]
[Equation 8]

And the magnification is
[0051]
[Equation 9]

It becomes.
[0052]
That is, the magnification is a function of only the position of the color filter 81 and the focal length f2 of the second convex lens 65, and does not depend on the focal length f1 of the first convex lens 62.
[0053]
The formula for obtaining the minimum size in this system is obtained by substituting t = f2 into the formula (5) of the minimum size in the general formula,
[0054]
[Expression 10]

It becomes. On the other hand, since the image is a real image and the aperture stop 63 is between both lenses,
f2 ≧ f1 ≧ f2 / 2 (17)
It is. Under this condition, L in formula (16) ₀ To minimize
f1 = f2 / 2 (18)
At the time. That is, the case of f2 = t and f1 = f2 / 2 is also a preferable arrangement from the viewpoint that the system can be made compact.
[0055]
The imaging formula at this time is
b = f2 (f2-a) / a (19)
And the image magnification is
m = f2 / a (20)
It is. From equation (19), a ≦ f2. From the formula (20), the magnification is minimum when a = f2, and monotonously increases as the color filter 81 is brought closer to the lens.
[0056]
In the configuration in which f2 = t and the equation (18) is satisfied, the condition for minimizing the system is a = f2, and L at this time ₀ Is 2 · f2 (= 2t), and b is b = 0 from the equation (19).
[0057]
In addition to the extremely compact system size of 2 · f2, this arrangement allows b = 0, that is, the second convex lens 65 and the screen 30 are in close contact with each other, so that an image can be observed with a transmission screen. It is suitable for. Moreover, it can be used for both transmission and reflection methods.
[0058]
FIG. 4 shows a configuration diagram of a color filter defect inspection apparatus using the optical apparatus 60 described above with reference to FIG. 1 or FIG. This inspection apparatus uses a parallel light source and observes light transmitted through a color filter that is an object to be inspected. In the present embodiment, the color filter refers to a color filter having at least one color of a colored layer such as RGB (Red, Green, Blue) on a substrate. In this basic configuration, a protective layer and an electrode layer are provided. Additions are also included. Specifically, for example, a layer in which at least one color of R, G, B is formed on a transparent substrate, a black matrix is formed on the substrate, and an RGB color filter layer is formed between them Further, a layer on which an overcoat layer is further provided if necessary, a layer having a transparent electrode formed thereon, and a layer having an additional layer on the basis of the structure thereof. .
[0059]
In addition, as a method for producing a color filter, there are a dyeing method, a pigment dispersion method, a printing method, and an electrodeposition method. It is. In addition, the inspection method and inspection apparatus of the present invention can be applied to intermediate products and final products in each process in the manufacture of color filters.
[0060]
As shown in FIG. 4, the apparatus includes (a) a parallel light source 12 that outputs inspection light L <b> 21 that irradiates the color filter 81 to be inspected, and (b) holds the color filter 81 and The incident angle variable holder 20 that changes the angle formed by the optical axis and the light receiving surface of the color filter 81, and (c) the light L23 that passes through the color filter 81 as a result of the irradiation of the inspection light L21 is condensed and projected light L25. The optical device 60 that forms an image of the color filter 81 in the image space, (d) the projection screen 30 that forms an image on the surface of the optical device 60, and (e) the projection onto the projection screen 30. The image pickup device 40 for picking up the projected image of the projected light L25, and (f) collecting and displaying the image pickup result by the image pickup device 40, and also the inspection light L2 on the incident angle variable holder Of instructing the angle formed between the light-receiving surface of the optical axis and the color filter 81, further comprising a processing unit 50 for indicating the position of the lens barrel 61 of the optical device 60 to the lens barrel holder 64.
[0061]
As already described in detail for its basic configuration, the optical device 60 includes convex lenses 62 and 65 and an aperture stop 63 provided between both lenses. These optical elements are supported by the lens barrel 61 while maintaining a predetermined positional relationship. The lens barrel 61 is movable along a moving plane substantially perpendicular to the optical axis of the light that the inspection light L21 has transmitted through the color filter 81 (which coincides with the optical axis of the inspection light L21) by the lens barrel holder 64. Is retained. The position of the lens barrel 61 on the moving surface is determined based on an instruction given from the processing unit 50 to the lens barrel holder 64 as described above.
[0062]
The parallel light source 12 includes a high-intensity point light source 11 such as a high-pressure mercury lamp or a xenon lamp, and a collimating lens system 13 that collimates the light output from the point light source 11. In addition, a solar ray may be used by using a reflecting mirror or the like.
[0063]
The inspection light output from the parallel light source 12 may be monochromatic light or white light, and each has advantages. When the object to be inspected is a color filter as in this embodiment, white light is advantageous in that each pixel of R, G, and B can be observed in that color, and the cause of color unevenness is R, G. , B is advantageous in that it can be analyzed. In addition, depending on the color unevenness, the use of monochromatic light often appears more clearly.
[0064]
The apparatus of the present embodiment configured as described above executes the color filter defect inspection method as follows.
[0065]
First, the processing unit 50 instructs the variable incident angle holder 20 holding the color filter 81, and the optical axis of the inspection light and the inspection light receiving surface of the color filter 81 intersect at a predetermined angle (for example, orthogonal). Set to
[0066]
In this state, the color filter 81 is irradiated with the inspection light L21 output from the parallel light source 12. The transmitted light L23 transmitted through the color filter 81 in response to the irradiation of the inspection light L21 is collected by the optical device 60 and reaches the projection screen 30 as the projection light L25. At this time, when the scattered light is blocked by the aperture stop 63, an image is formed only by the direct light (bright field image), and when the direct light is blocked, an image is formed by the scattered light (dark field image). .
[0067]
The projection screen 30 is installed at a position where the image of the color filter 81 becomes the clearest. This projected image reflects defects such as the state of the color filter 81, that is, abnormal color tone, and the occurrence of interference fringes and unevenness due to the light source image are reduced. In particular, since the light that diverges on the surface of the color filter 81 is condensed on the image plane by the optical device 60, the projected image is clearly displayed as compared with the case where the optical device 60 is not used. Defects can be detected with high sensitivity.
[0068]
Thus, the image pickup device 40 picks up the projection image projected on the projection screen 30 and the processing unit 50 collects the image pickup result. The processing unit 50 displays an image processing result based on the collected imaging result, and stores or prints the imaging result and the processing result as necessary.
[0069]
Then, the defect of the color filter 81 is detected based on the display result, the storage result, or the printing result by the processing unit 50. In the projected image projected on the projection screen 30, the occurrence of interference fringes and the unevenness due to the light source image are reduced, so that it is possible to discriminate defects such as subtle color tone abnormalities.
[0070]
In this embodiment, the image is formed by the light transmitted through the object. However, the object may be irradiated with light and the image may be formed by the reflected light.
[0071]
When the area of the color filter 81 is large, considering that the inspection light L 21 is substantially parallel light, the optical device 60 can project only a part of the color filter 81 on the projection screen 30. Therefore, in this embodiment, the lens barrel 61 of the optical device 60 can be translated in a plane substantially perpendicular to the optical axis of the transmitted light L23.
[0072]
The parallel movement of the lens barrel 61 is achieved when the lens barrel holder 64 receives an instruction from the processing unit 50. That is, the lens barrel holder 64 is provided with a mechanism that allows the lens barrel 61 to translate in a plane substantially perpendicular to the optical axis of the transmitted light L23, and the lens barrel 61 is subjected to main scanning and sub-scanning by this translation mechanism. As a result, the entire surface of the color filter 81 can be projected on the projection screen 30.
[0073]
In this embodiment, the lens barrel 61 is translated, but instead, the color filter 81 may be translated in a plane substantially perpendicular to the optical axis of the inspection light L21.
[0074]
In the present embodiment, the image pickup device 40 is used, but instead of this, it is also possible to detect a defect of the color filter 81 by visually observing the projected image on the projection screen 30. Also in this case, in the projection image projected on the projection screen 30, the occurrence of interference fringes and the unevenness due to the light source image are reduced, so that it is possible to discriminate defects such as subtle color tone abnormalities.
[0075]
Next, even if the above-described inspection operation is performed, the light intensity change in the projection image may be gradual and the presence or absence of defects may not be clear.
[0076]
In such a case, the processing unit 50 instructs the incident angle variable holding unit 20 to change the angle formed by the optical axis of the inspection light L21 and the light receiving surface of the inspection light L21 of the color filter 81. After changing the angle or changing the angle, again, in the same manner as described above, the color filter 81 is irradiated with the inspection light L21, and the transmitted light L23 transmitted through the color filter 81 is projected onto the projection screen to observe the projection image. To do. Observe the projected image with the same light intensity change at the short distance in the image as in the previous observation, or the projected image with the difference in the optical path length due to the uneven thickness in the layer with the uneven thickness. Therefore, the defect can be inspected with high accuracy.
[0077]
Each of the first convex lens 62 and the second convex lens 65 of the optical device 60 is a single lens, but any combination lens or spherical mirror having the function of a convex lens can be used as long as it can converge light. Other imaging optical means may be used.
[0078]
The aperture stop 63 is for increasing the contrast of the image by selecting light passing on the rear focal plane of the first convex lens 62. Therefore, any shape can be used as long as it meets this purpose. For example, a hole is formed in a heat-resistant sheet, and a small disk that cuts only light directly is provided at the center thereof, or a groove that allows only scattered light to pass concentrically is provided. The inventors of the present invention most simply made a hole with a diameter of about 5 mm in a heat-resistant sheet, and moved the heat-resistant sheet in a direction perpendicular to the optical axis to select a desired light and obtained a good result. ing. Further, as described above, the position of the aperture stop 63 on the optical axis must be between the first convex lens 62 and the second convex lens 65. The inter-lens distance t and the focal length of the first convex lens 62 are as follows. There is a relationship t ≧ f1 with f1.
[0079]
Finally, photographs taken of the images obtained by the defect inspection method of the present invention are shown in FIGS.
[0080]
FIG. 5 shows an image formed on the screen 30 when the hard coat PMMA plate is irradiated with light having a wavelength of 589 nm and the reflected light is condensed by the optical device 60. A bright field image is obtained by adjustment. Note that the large circle at the center is drawn in advance on the hard coat PMMA plate to show the point of interest and is not a defect. The conditions regarding the optical device 60 at this time are as follows. The focal lengths f1 and f2 of the first and second convex lenses are 25 cm, the inter-lens distance t is 25 cm, the distance a between the object and the first convex lens is 12 cm, and the distance b between the second convex lens or aperture stop and the screen is 52 cm. is there.
[0081]
FIG. 6 is a photograph when the STN type color filter is irradiated with inspection light and the transmitted light is condensed by the optical device 60 to form a dark field image on the screen 30. It can be seen that uneven color appears in the center. Also in this example, as in FIG. 5, f1 = f2 = t = 25 cm, a = 12 cm, and b = 52 cm.
[0082]
FIG. 7 is a photograph when a TFT type color filter is irradiated with inspection light and the reflected light is condensed by the optical device 60 to form a dark field image on the screen 30. The black dot at the center is a so-called “navel spot” that appears at the center of rotation when spin coating is performed on the surface. It can be seen that this clearly appears as a dark field image. Also in this example, as in FIG. 5, f1 = f2 = t = 25 cm, a = 12 cm, and b = 52 cm.
[0083]
【The invention's effect】
As described above, when the defect inspection method and defect inspection apparatus of the present invention are used, fine color abnormalities and scratches that are difficult to visually observe appear clearly, so that the defect of the object can be inspected quickly and stably. can do.
[Brief description of the drawings]
FIG. 1 is a layout view showing a basic configuration of an optical device 60 used in an object defect inspection apparatus according to an embodiment of the present invention.
FIG. 2 is a view showing a preferred arrangement of an optical device 60. FIG.
FIG. 3 is a diagram showing a configuration of a conventional Fourier transform lens.
FIG. 4 is a configuration diagram showing an object defect inspection apparatus according to an embodiment of the present invention.
FIG. 5 is a photograph showing an image formed using the apparatus of this embodiment.
FIG. 6 is a photograph showing an image formed using the apparatus of this embodiment.
FIG. 7 is a photograph showing an image formed using the apparatus of this embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 ... Point light source, 12 ... Parallel light source, 20 ... Incident angle variable holder, 30 ... Projection screen, 40 ... Imaging device, 50 ... Processing part, 60 ... Optical apparatus, 61 ... Lens tube, 62 ... First convex lens, 63 ... Aperture stop, 65 ... second convex lens, 81 ... color filter.

Claims (23)

An object is irradiated with inspection light, and an image of the object is formed by condensing light transmitted through or reflected by the object using an optical device, and the object is observed by observing the image. A method for inspecting defects in
The optical device includes first imaging optical means for condensing light transmitted through or reflected by the object, and light transmitted through or reflected by the object disposed at a rear focal plane of the first imaging optical means. An aperture stop that shields either scattered light or direct light of the light, and second imaging optical means that images the scattered light or direct light that is disposed behind the aperture stop and passes through the aperture stop. A focal length F is finite, and a distance t between the first imaging optical means and the second imaging optical means is equal to a focal length f1 of the first imaging optical means . Defect inspection method.   2. The object defect inspection method according to claim 1, wherein a focal length f2 of the second imaging optical means is equal to the focal length f1.   3. The object defect inspection method according to claim 2, wherein the object is disposed on a front focal plane of the first imaging optical means.   2. The object defect inspection method according to claim 1, wherein a focal length f2 of the second imaging optical means is equal to a half of the focal length f1.   The defect inspection method for an object according to claim 4, wherein the object is disposed so as to be in contact with the first imaging optical unit. An object is irradiated with inspection light, and an image of the object is formed by condensing light transmitted through or reflected by the object using an optical device, and the object is observed by observing the image. A method for inspecting defects in
The optical device includes first imaging optical means for condensing light transmitted through or reflected by the object, and light transmitted through or reflected by the object disposed at a rear focal plane of the first imaging optical means. An aperture stop that shields either scattered light or direct light of the light, and second imaging optical means that images the scattered light or direct light that is disposed behind the aperture stop and passes through the aperture stop. A focal length F is finite, and a distance t between the first imaging optical means and the second imaging optical means is equal to a focal distance f2 of the second imaging optical means. Defect inspection method.   7. The object defect inspection method according to claim 6, wherein a focal length f1 of the first imaging optical means is equal to a half of the focal length f2.   8. The object defect inspection method according to claim 7, wherein the object is disposed at a position separated from the first imaging optical means by the focal length f2 in front of the first imaging optical means.   The defect inspection method for an object according to claim 1, wherein the inspection light is substantially parallel light.   The defect inspection method for an object according to claim 1, wherein the inspection light is monochromatic light.   The object defect inspection method according to claim 1, wherein the image is observed by projecting the image onto a screen.   The defect inspection method for an object according to claim 1, wherein the object is a color filter. A light source that outputs inspection light that irradiates an object to be inspected, and an optical device that forms an image of the object by condensing light transmitted through or reflected by the object,
The optical device includes first imaging optical means for condensing light transmitted through or reflected by the object, and light transmitted through or reflected by the object disposed at a rear focal plane of the first imaging optical means. An aperture stop that shields either scattered light or direct light of the light, and second imaging optical means that images the scattered light or direct light that is disposed behind the aperture stop and passes through the aperture stop. A focal length F is finite, and a focal length f1 of the first imaging optical means is equal to a distance t between the first imaging optical means and the second imaging optical means. Defect inspection equipment.   14. The object defect inspection apparatus according to claim 13, wherein a focal length f2 of the second imaging optical means is equal to the distance t.   15. The defect inspection apparatus for an object according to claim 14, wherein the arrangement position of the object is a front focal plane of the first imaging optical means.   14. The object defect inspection apparatus according to claim 13, wherein a focal length f2 of the second imaging optical means is equal to a half of the focal length f1.   The object defect inspection apparatus according to claim 16, wherein the object is disposed in contact with the first imaging optical unit. A light source that outputs inspection light that irradiates an object to be inspected, and an optical device that forms an image of the object by condensing light transmitted through or reflected by the object,
The optical device includes first imaging optical means for condensing light transmitted through or reflected by the object, and light transmitted through or reflected by the object disposed at a rear focal plane of the first imaging optical means. An aperture stop that shields either scattered light or direct light of the light, and second imaging optical means that images the scattered light or direct light that is disposed behind the aperture stop and passes through the aperture stop. A focal length F is finite, and a distance t between the first imaging optical means and the second imaging optical means is equal to a focal distance f2 of the second imaging optical means. Defect inspection equipment.   19. The object defect inspection apparatus according to claim 18, wherein a focal length f1 of the first imaging optical means is equal to a half of the focal length f2.   20. The object defect inspection apparatus according to claim 19, wherein the object is disposed at a position separated from the first imaging optical means by the focal length f2 in front of the first imaging optical means.   21. The object defect inspection device according to claim 13, further comprising a screen that forms an image formed by the optical device on a surface thereof.   The defect inspection apparatus for an object according to any one of claims 13 to 21, wherein the light source outputs substantially parallel light.   The said object is a color filter, The defect inspection apparatus of the object as described in any one of Claims 13-22 characterized by the above-mentioned.

Images