JP4012798B2 - Method and apparatus for measuring surface roughness using laser reflected light - Google Patents

Description

【００２９】
数１において、σ_ｈは被測定物９の表面の２乗表面粗さ、ｋ（＝２π／λ）は波数、θ_０は被測定物９の表面の法線方向とＣＣＤ素子１７の撮像方向とのなす角度、Ｌ_０はレーザ光の照射点１０とＣＣＤ素子１７の間の距離を示す。また、最大値の位置Ａｘは数２に示すように表され、レーザ光の照射角度の変化δθによる粒状斑点模様の移動距離を意味する。
【００３０】
【数２】

【００３１】
図４に示すように、レーザ光を基準角度θｓで照射したときの基準粒状斑点模様１１ａの自己相関をとり、その結果を３次元表示すると、図６（ｂ）に示すような中央に最大値Ｃ_１１を有する形状になる。
次に、レーザ光の照射角度をδθ変化させたときの変化粒状斑点模様１１ｂと基準粒状斑点模様１１ａとの相互相関をとり、その結果を３次元表示すると、図６（ｂ）に示すように最大値の位置がＡｘだけ移動し、最大値Ｃ_１２が前記最大値Ｃ_１１より減少した形状になる。この最大値Ｃ_１２に着目して、自己相関関数の最大値Ｃ_１１に対する相互相関関数の最大値Ｃ_１２の割合を百分率で表したものが一致度である。
また、相互相関関数の最大値の位置の移動距離（Ａｘ）は、粒状斑点模様の移動量を示しており、レーザ光の照射角度の変化分に相当する。
本発明に係るレーザ反射光による表面粗さ測定装置は、前記一致度の変化を移動距離（Ａｘ）に対して表した一致度変化率によって被測定物９の表面粗さを求めるようにしてある。
【００３２】
なお、基準粒状斑点模様１１ａと変化粒状斑点模様１１ｂの変化量を算出し、該変化量から変化率（変化量／照射角度の変化量）を算出することにより被測定物の表面粗さを求めることも可能である。
ここで、基準粒状斑点模様１１ａと変化粒状斑点模様１１ｂの変化量とは、粒状斑点模様の輪郭、又は輪郭と濃淡の変化量をいい、上述のように基準粒状斑点模様１１ａと変化粒状斑点模様１１ｂをとった場合には、相互相関関数の最大値Ｃ_１２の差によって表される。
【００３３】
相関関数の計算には、粒状斑点模様の各画像のフーリエ変換の共役積をとり、それをフーリエ変換して求めることができる。または、フーリエ変換の共役積をとる代わりに、フーリエ変換の位相部分のみを使用する位相限定相関法を使用することもできる。図示の実施例では、位相限定相関法を使用して相関関数を求めるようにしてあり、位相限定相関法を使用した本測定装置の構成について説明する。
【００３４】
図１又は図２に示す実施例において、レーザ投光機１は、レーザ素子、冷却回路、駆動回路、及びレンズより構成され、被測定物９に安定した粒状斑点模様を描くために、直進性・高輝度・指向性・干渉性に優れたレーザ光を被測定物９の表面に照射するようにしてある。
図示の実施例では、レーザ投光機１は、波長６７０ｎｍ、出力４ｍＷの赤色光を使用し、平行光を照射するようにしてある。レーザ投光機１のレンズは、照射するレーザ光のビーム径を変えることができるように設けてあり、レーザ光を照射した領域での平均表面粗さを直接求めることができるように構成してある。また、表面粗さ測定中において、粒状斑点模様の大きさを一定に維持するために、照射するレーザ光のビーム径は固定することができるようにしてある。
なお、レーザ光は、平行光に限らず、収束光、発散光のいずれを使用することもできる。
【００３５】
照射角度調整機構２は、図２に示すように、回転軸１２と、レーザ投光機１を保持する保持部材１３と、該保持部材１３を回転軸１２に支持する支持部材１４とからなる。
保持部材１３は、回転軸１２の軸中心の延長線上の照射点１０にレーザ光を照射することができるように、レーザ投光機１を保持するように設けてある。この構成により、回転軸１２を中心に回動してレーザ投光機１の向きを偏向しても、常に照射点１０にレーザ光を照射することができると共に、投光機１と照射点１０の距離を一定に保った状態でレーザ光の照射角度を変化させることができる。従って、投光機１と照射点１０の距離変化による粒状斑点模様の変化を防ぐことができ、レーザ光の照射角度の変化による粒状斑点模様の変化を測定することができる。
【００３６】
また、回転軸１２には、ステッピングモータ１５を設けてあり、微小角度δθずつ回転軸１２を回動させて、レーザ投光機１の向きを偏向することができるようにしてある。回転軸１２の回動手段は、安定して回動させることができるから、ステッピングモータを使用することが好ましいが、表面粗さを求めるときに角度δθの値は必ずしも必要でないことから、回動角度の調整が容易なサーボモータにより回動させることもでき、ラチェット機構により微小角度δθずつ回動して固定することができるようにすることも可能である。
また、１６は、被測定物９を固定する固定器具であり、図示の実施例では、Ｘ−Ｙステージを使用して被測定物９の表面粗さ測定箇所を照射点１０に合わせて固定することができるようにしてある。
【００３７】
ＣＣＤカメラ３は、ＣＣＤ素子（Ｃｈａｒｇｅ Ｃｏｕｐｌｅｄ Ｄｅｖｉｃｅ：電荷結合素子）１７と該ＣＣＤ素子１７の前方に設けた外来光を遮断する暗視筒１８とからなり、レンズを介さないで粒状斑点模様を直接撮像するように構成してある。
また、ＣＣＤカメラ３は、ＣＣＤ素子１７により被測定物９に描く粒状斑点模様を撮像し、アナログ信号で画像処理装置４へ出力するようにしてある。
【００３８】
また、図１又は図２に示すように、ＣＣＤカメラ３は、被測定物９の表面の法線方向に固定して設けてある。被測定物９の表面の凹凸による死角の影響を受けることなく粒状斑点模様を撮像することができ、精度良く表面粗さを測定することができるから、ＣＣＤカメラ３を被測定物９の表面の法線方向に設けることが最も好ましいが、被測定物９の表面の法線方向に限定されるものではなく、粒状斑点模様を撮像できるように被測定物９の表面に対向する向きにＣＣＤカメラ３を設けてあれば良い。例えば、図４に示すように、ＣＣＤカメラ３を被測定物９の表面の法線方向から角度θ_０だけ傾けて照射点１０を撮像するように設けることもできる。
【００３９】
図１又は図２に示す実施例において、画像処理装置４は、位相限定相関処理機能を有する位相限定相関処理装置７と画像処理用コンピュータ８とからなり、ＣＣＤカメラ３により撮像された基準粒状斑点模様１１ａと各照射角度における変化粒状斑点模様１１ｂの相関をとり、相互相関関数の最大値Ｃ_１２を基準粒状斑点模様１１ａの自己相互相関関数の最大値Ｃ_１１と比較して粒状斑点模様の一致度を算出し、各照射角度における該一致度の変化から被測定物９の表面粗さを求めるように構成してある。
【００４０】
位相限定相関処理装置７は、超集積回路（ＶＬＳＩ）により構成され、図示しないが、Ａ／Ｄ変換部と、フーリエ変換部と、制御部とからなる。
Ａ／Ｄ変換部は、ＣＣＤカメラ３から送られた粒状斑点模様のアナログ信号をディジタル信号化し、フーリエ変換部へ送るようにしてある。
フーリエ変換部は、ディジタル信号化された画像データに２次元離散的フーリエ変換（ＤＦＴ）を施し、画像データを周波数領域に変換することにより、振幅成分（濃淡データ）と位相成分（像の輪郭データ）に分解するようにしてある。制御部は、上述したように、フーリエ変換された画像データから位相成分のみを抽出し、基準粒状斑点模様１１ａと変化粒状斑点模様１１ｂの相関をとるように構成してある。
【００４１】
位相限定相関処理装置７により、画像データのフーリエ変換の位相成分のみを使用して基準粒状斑点模様１１ａと変化粒状斑点模様１１ｂの相関をとるようにしたから、レーザ光の照度差や被測定物９の表面の反射率等による粒状斑点模様の明暗の影響を受けることなく表面粗さを測定することができると共に、相関処理を超集積回路に行わせることによって、従来のプログラムによる演算よりも処理を高速化することができ、表面粗さの測定時間を短縮することができる。
なお、制御部は、画像のフーリエ変換の位相成分のみを抽出する場合に限らず、ｌｏｇ処理や√処理等の抑制処理によって振幅を抑制し、データ量を削減すると共に位相成分に重みを持たせて基準粒状斑点模様１１ａと変化粒状斑点模様１１ｂの相関をとるようにすることも可能である。
【００４２】
図１に示す実施例において、画像処理用コンピュータ８は、各照射角度における一致度を粒状斑点模様の移動距離Ａｘと対応させて表すようにしてある。
図７乃至図９に示すように、横軸には粒状斑点模様の移動距離Ａｘ（μｍ）をとり、縦軸には基準粒状斑点模様１１ａと変化粒状斑点模様１１ｂの一致度をとり、レーザ光の各照射角度において位相限定相関処理装置７により算出された一致度をプロットしてある。そして、レーザ光の照射角度の変化に対する前記一致度の変化を最小自乗法により平均化し直線として表し、該直線の傾きを求めることにより一致度の変化率を算出するように構成してある。
【００４３】
また、画像処理用コンピュータ８は、記憶部を有し、該記憶部は、表面粗さが既知である複数の比較用表面粗さ標準片を測定して求めた前記直線の傾き（標準変化率）を記憶するように構成してある。
図７乃至図９に示すグラフは、本表面粗さ測定装置によって、比較用表面粗さ標準片の表面粗さを測定した結果である。粗さ番号ＳＮ−５の傾きは−０．０２６４であり、粗さ番号ＳＮ−８の傾きは−０．０２８９であり、粗さ番号ＳＮ−１０の傾きは−０．０３５１であり、粗さ番号が増す（表面粗さが増す）毎に一致度の標準変化率である前記直線の傾きが大きくなっている。
この関係から、画像処理用コンピュータ８は、被測定物９の一致度の変化率を標準変化率と比較照合して、被測定物９の一致度の変化率に最も近い標準変化率の比較用表面粗さ標準片を選び出し、該比較用表面粗さ標準片の粗さ番号を被測定物９の表面粗さとして求めるようにしてある。
【００４４】
図１に示す実施例において、５は、表示出力装置であり、画像処理装置４により求めた被測定物９の一致度の変化率、表面粗さ等の測定結果を画面上に表示することができるようにしてある。
また、６は、印字出力装置であり、画像処理装置４により求めた被測定物９の一致度の変化率、表面粗さ等の測定結果を紙、フィルム等に印刷することができるようにしてある。
【００４５】
上記のように構成されたレーザ反射光による表面粗さ測定装置により、以下のように被測定物の表面粗さの測定を行う。
図１に示すように、被測定物９の表面粗さを測定する測定箇所を選び、レーザ光の照射点１０に該測定箇所を合わせて固定器具１６に被測定物９を固定する。そして、レーザ投光機１を照射角度調整機構２により被測定物９の表面の法線方向から基準角度θｓ傾け、レーザ光を被測定物９の表面に照射すると共に、レーザ光の反射光である粒状斑点模様をＣＣＤカメラ３により撮像する。
ＣＣＤカメラ３により撮像された粒状斑点模様は、位相限定相関処理装置７に送られ、画像データをディジタル化した後、２次元離散的フーリエ変換（ＤＦＴ）を施し、振幅と位相により表される周波数領域に変換する。この基準粒状斑点模様１１ａのフーリエ変換された画像データに位相限定処理を行い、位相成分のみを抽出し、位相限定相関処理装置７に記憶する。
【００４６】
次に、ステッピングモータ１５により照射角度調整機構２を微小角度δθずつ回動させることにより、レーザ光の被測定物９への照射点１０を中心にレーザ投光機１を傾き方向に微小角度δθずつ偏向させながらレーザ光を照射する。
従って、レーザ光の被測定物９への照射点１０の位置を固定することができると共に、レーザ投光機１と照射点１０の距離を一定に保った状態で、レーザ光の照射角度を基準角度θｓから微小角度δθずつ変化させながらレーザ光を被測定物９の表面に照射することができる。
【００４７】
このようにレーザ光の照射角度を微小角度δθずつ変化させながら照射することにより、図６に示すように、ＣＣＤカメラ３に撮像される粒状斑点模様は、レーザ光の照射角度の変化に対応して移動していき、連続する粒状斑点模様がＣＣＤカメラ３に撮像される。
すなわち、被測定物９の表面の法線方向から基準角度θｓ傾けてレーザ光を被測定物９の表面に照射すると、基準粒状斑点模様１１ａが撮像される。そして、照射角度を微小角度δθ_１変化させると、基準粒状斑点模様１１ａから角度δθ_１に対応する距離Ａｘだけ移動した位置に形状も変化した変化粒状斑点模様１１ｂ_１が撮像される。このように、微小角度δθ_１、δθ_２、・・・、δθ_ｎと照射角度を変化させると、角度δθ_１、δθ_２、・・・、δθ_ｎに対応する距離Ａｘだけ移動した位置に、変化粒状斑点模様１１ｂ_０、１１ｂ_１、・・・、１１ｂ_ｎが撮像される。
【００４８】
そして、それぞれの照射角度においてＣＣＤカメラ３により撮像された変化粒状斑点模様１１ｂ_１、１１ｂ_２、・・・、１１ｂ_ｎは、基準粒状斑点模様１１ａと同様に、位相限定相関処理装置７に送られ、画像データをディジタル化した後、２次元離散的フーリエ変換（ＤＦＴ）を施し、振幅と位相により表される周波数領域に変換する。
この変化粒状斑点模様１１ｂのフーリエ変換された画像データに位相限定処理を行い、位相成分のみを抽出する。
この位相限定処理された変化粒状斑点模様１１ｂの画像データと、位相限定相関処理装置７に記憶されている位相限定処理された基準粒状斑点模様１１ａの画像データとの相関をとることによって、図６（ｂ）に示すような相互相関関数が得られる。このとき、基準粒状斑点模様１１ａの自己相関関数の最大値Ｃ_１１を１００としたときの、変化粒状斑点模様１１ｂと基準粒状斑点模様１１ａの相互相関関数Ｃ_１２の最大値が一致度である。
【００４９】
そして、各照射角度において算出された基準粒状斑点模様１１ａと変化粒状斑点模様１１ｂ_１、１１ｂ_２、・・・、１１ｂ_ｎの一致度は、画像処理用コンピュータ８に送られる。
画像処理用コンピュータ８は、図７乃至図９に示すように、横軸に粒状斑点模様の移動距離Ａｘ（μｍ）、縦軸に変化粒状斑点模様１１ｂ_ｎと基準粒状斑点模様１１ａの一致度をとり、前記一致度を図にプロットし、粒状斑点模様の移動距離Ａｘに対する前記一致度の変化を最小自乗法により平均化して直線で表し、該直線の傾きを求めることにより一致度の変化率を算出することができる。
【００５０】
上記の測定方法により、予め表面粗さが既知である複数の比較用表面粗さ標準片を測定して一致度の標準変化率を算出し、画像処理用コンピュータ８の記憶部に記憶させておく。
同様にして、被測定物９を測定して算出した一致度の変化率を、記憶部に記憶してある標準変化率と比較照合し、該一致度の変化率に最も近い標準変化率の比較用表面粗さ標準片を選び出すことにより、該比較用表面粗さ標準片の粗さ番号を被測定物９の表面粗さとして求めることができる。
【００５１】
次に、第二の実施例について説明する。
図５に示す実施例において、本発明に係るレーザ反射光による表面粗さ測定装置は、被測定物９の表面に法線方向から基準角度θｓ傾けてレーザ光を照射するように設けたレーザ投光機１と、レーザ光の反射光である粒状斑点模様を撮像するように被測定物９の表面に対向する向きに設けた撮像機３と、レーザ光の被測定物９への照射点１０を中心にレーザ投光機１と撮像機３を結ぶ方向に被測定物９をレーザ投光機１と撮像機３に対して相対的に偏向させることによりレーザ光の照射角度を基準角度θｓから変化させる照射角度調整機構１９と、レーザ光を基準角度θｓから照射したときの粒状斑点模様である基準粒状斑点模様１１ａを基準にして、レーザ光の照射角度を基準角度θｓから変化させたときの粒状斑点模様である変化粒状斑点模様１１ｂの変化を測定することにより被測定物９の表面粗さを求める画像処理装置とから構成してある。
【００５２】
レーザ投光機１は、図５に示すように、測定開始状態において、被測定物９の表面の法線方向から基準角度θｓ傾けて、被測定物９の照射点１０にレーザ光を照射することができるように固定して設けてあると共に、ＣＣＤカメラ３は、被測定物９の表面の法線方向に固定して設けてある。
【００５３】
図５に示す実施例において、照射角度調整機構１９は、照射点１０を中心にレーザ投光機１と撮像機３を結ぶ方向に固定器具１６を微小角度δθずつ回動することができるようにステッピングモータ１５を設けてあり、固定器具１６に固定された被測定物９を偏向させることにより、レーザ光の照射角度を基準角度θｓから変化させるように構成してある。
【００５４】
また、図示の実施例のように、被測定物９を偏向させてレーザ光の照射角度を変化させる場合に限らず、被測定物９を固定しておき、撮像機３とレーザ投光機１を結ぶ方向に、レーザ投光機１及び撮像機３を一体的に偏向させてレーザ光の照射角度を変化させることも可能である。
また、照射角度の異なる複数個のレーザ投光機１を設けておき、順次切り替えてレーザ光を照射することにより、レーザ光の照射角度を変化させるように設けることもできる。
なお、その他の構成は、図１に記載の実施例と同様である。
【００５５】
次に、第三の実施例について説明する。
図１又は図５に記載の構成において、画像処理用コンピュータ８は、変化粒状斑点模様１１ｂと基準粒状斑点模様１１ａの一致度を算出し、前記数１の理論式に基づいて前記一致度Ｙの変化を移動距離Ｘの関数として表し、該関数の係数から被測定物９の表面粗さを求めるように構成してある。
一致度Ｙは、移動距離Ｘの２次関数で表され、横軸に粒状斑点模様の移動距離Ｘ（μｍ）、縦軸に変化粒状斑点模様１１ｂ_ｎと基準粒状斑点模様１１ａの一致度Ｙをとると、図１０乃至図１３に示すように表される。
【００５６】
図１０乃至図１３に示すように、移動距離Ｘの一次の項の係数の絶対値は、被測定物９の表面の凹凸の平均高さｈが高くなるにしたがって大きくなるという関係がある。この関係を利用して、画像処理用コンピュータ８は、移動距離Ｘの一次の項の係数から直接的に被測定物９の表面粗さを求めるように構成してある。
【００５７】
また、図１又は図４に記載の実施例において、位相限定相関処理装置７を設けないで、濃淡データを含む基準粒状斑点模様１１ａと変化粒状斑点模様１１ｂの相関をとることにより一致度を求めることも可能であると共に、前記一致度に限らず、画像処理用コンピュータ８により基準粒状斑点模様１１ａと変化粒状斑点模様１１ｂの一致度や歪量等の変化量を算出して、被測定物９の表面粗さを求めるように構成することも可能である。
すなわち、画像処理装置４は、画像データを位相限定相関処理することなく、濃淡データを含む基準粒状斑点模様１１ａの任意の画素毎の濃淡を認識し、ＣＣＤカメラ３から送られてくる変化粒状斑点模様１１ｂと前記認識した濃淡を位置的に照合し、粒状斑点模様の歪により変化した量をＣＣＤ素子１７の画素単位に演算することにより、基準粒状斑点模様１１ａと変化粒状斑点模様１１ｂの歪量等の変化量を算出して、被測定物９の表面粗さを求めるようにすることも可能である。
【００５８】
なお、被測定物の表面粗さの測定には、被測定物９の表面がレーザ光を透過する透明な物質で覆われている場合も含まれる。
また、被測定物９の表面形状は、図示の実施例のように平面状のものに限らず、曲面状のものでも測定することができる。さらに、照射するレーザ光の径を絞ることにより、被計測物９の表面形状が複雑な場合にも、各部位の独自の領域での測定も可能である。
【００５９】
【発明の効果】
以上の通り、本発明に係るレーザ反射光による表面粗さ測定方法によれば、レーザ投光機を被測定物の表面の法線方向から基準角度傾けてレーザ光を前記被測定物の表面に照射し、次に、レーザ光の前記被測定物への照射点を中心に前記レーザ投光機を傾き方向に偏向させることによりレーザ光の照射角度を前記基準角度から変化させながらレーザ光を照射すると共に、前記被測定物の表面に対向する向きに固定した撮像機により前記レーザ光の反射光である粒状斑点模様を撮像し、レーザ光を前記基準角度から照射したときの粒状斑点模様である基準粒状斑点模様を基準にして、レーザ光の照射角度を前記基準角度から変化させたときの粒状斑点模様である変化粒状斑点模様の変化を測定することにより前記被測定物の表面粗さを求める構成を有することにより、粒状斑点模様の変化により被測定物の表面粗さを求めるから、被測定物の材質・形状等の測定面の影響を受けることなく非接触式により被測定物の表面粗さを測定することができ、被測定物の表面に傷つけることがなく、測定者の経験によらず一定の精度で表面粗さの測定をすることができる効果がある。
【００６０】
また、本発明は、レーザ投光機を被測定物の表面の法線方向から基準角度傾けてレーザ光を前記被測定物の表面に照射すると共に、前記被測定物の表面に対向する向きに設けた撮像機により前記レーザ光の反射光である粒状斑点模様を撮像し、次に、レーザ光の前記被測定物への照射点を中心に前記レーザ投光機と前記撮像機を結ぶ方向に前記被測定物を前記レーザ投光機と前記撮像機に対して相対的に偏向させることによりレーザ光の照射角度を前記基準角度から変化させながらレーザ光を照射し、レーザ光を前記基準角度から照射したときの粒状斑点模様である基準粒状斑点模様を基準にして、レーザ光の照射角度を前記基準角度から変化させたときの粒状斑点模様である変化粒状斑点模様の変化を測定することにより前記被測定物の表面粗さを求める構成を有することにより、被測定物をレーザ投光機と撮像機に対して相対的に偏向させることによりレーザ光の被測定物への照射角度を変化させることができると共に、前記被測定物を偏向させることによってもレーザ光の照射角度を前記基準角度から変化させることができ、容易にレーザ光の照射角度を変化させることができる効果がある。
【００６１】
また、本発明は、前記被測定物の表面に対向する撮像機の向きが前記被測定物の表面の略法線方向である請求項１又は２に記載の構成を有することにより、被測定物の表面の凹凸による死角の影響を受けることなく前記粒状斑点模様を撮像することができるから、表面粗さを精度良く測定することができる効果がある。
【００６２】
また、本発明は、レーザ光の各照射角度において前記基準粒状斑点模様と前記変化粒状斑点模様の変化量を算出し、該変化量から変化率（変化量／照射角度の変化量）を算出することにより前記被測定物の表面粗さを求める請求項１乃至３のいずれかに記載の構成を有することにより、被測定物の表面粗さを前記変化率によって数値的に表すことができるから、客観的に被測定物の表面粗さを比較することができる効果がある。
【００６３】
また、本発明は、前記基準粒状斑点模様と前記変化粒状斑点模様の変化量が、前記基準粒状斑点模様と前記変化粒状斑点模様の一致度の変化量である請求項４に記載の構成を有することにより、基準粒状斑点模様と変化粒状斑点模様の一致度によっても粒状斑点模様の変化を測定することができ、一致度の変化量から被測定物の表面粗さを求めることができる効果がある。
【００６４】
また、本発明は、前記基準粒状斑点模様と前記変化粒状斑点模様の一致度の変化を前記変化粒状斑点模様の移動距離の関数で表し、該関数の係数から前記被測定物の表面粗さを求めるようにした請求項５に記載の構成を有することにより、前記関数の係数からレーザ光照射部分の２乗平均表面粗さを求めることができ、被測定物の表面粗さを直接的に求めることができる効果がある。
【００６５】
また、本発明は、前記関数の一次の項の係数から前記被測定物の表面粗さを求めるようにした請求項６に記載の構成を有することにより、表面粗さが増す毎に前記関数の一次の項の係数の絶対値が大きくなるという関係があるから、前記関数の一次の項の係数によって測定物の表面粗さを直接的に求めることができる効果がある。
【００６６】
また、本発明は、表面粗さが既知である複数の標準片の標準変化率を予め測定しておき、測定した被測定物の前記変化率を前記標準変化率と比較照合することにより前記被測定物の表面粗さを求める請求項４又は５に記載の構成を有することにより、被測定物の変化率に最も近い標準片の標準変化率を選び出すことにより、被測定物の表面粗さを標準片の表面粗さにより表すことができると共に、表面粗さが増す毎に変化率が大きくなるという関係から各標準片の表面粗さの中間値も表すことができる効果がある。
【００６７】
また、本発明は、撮像した前記粒状斑点模様を相関法により画像処理し、前記基準粒状斑点模様に対する前記変化粒状斑点模様の変化を測定する請求項１乃至８のいずれかに記載の構成を有することにより、撮像した前記粒状斑点模様を相関法により画像処理することにより、容易に変化粒状斑点模様の変化を測定することができる効果がある。
【００６８】
また、本発明は、前記相関法が位相限定相関法であり、前記粒状斑点模様の輪郭画像により前記基準粒状斑点模様に対する前記変化粒状斑点模様の変化を測定する請求項９に記載の構成を有することにより、位相限定相関法により画像処理し、前記粒状斑点模様のフーリエ変換の位相成分に対応する輪郭画像のみを比較するから、レーザ光の照度や被測定物の反射率等の違いによる粒状斑点模様の明暗レベルの変動によって測定誤差を生じないと共に、粒状斑点模様のデータ量が少なくなるので演算速度が早くなり、表面粗さの測定時間を短くすることができる効果がある。
【００６９】
また、本発明に係るレーザ反射光による表面粗さ測定装置によれば、被測定物の表面に法線方向から基準角度傾けてレーザ光を照射するように設けたレーザ投光機と、レーザ光の前記被測定物への照射点を中心に前記レーザ投光機を傾き方向に偏向させることによりレーザ光の照射角度を前記基準角度から変化させる照射角度調整機構と、前記レーザ光の反射光である粒状斑点模様を撮像するように前記被測定物の表面に対向する向きに固定して設けた撮像機と、レーザ光を前記基準角度から照射したときの粒状斑点模様である基準粒状斑点模様を基準にして、レーザ光の照射角度を前記基準角度から変化させたときの粒状斑点模様である変化粒状斑点模様の変化を測定することにより前記被測定物の表面粗さを求める画像処理装置とからなる構成を有することにより、粒状斑点模様の変化により被測定物の表面粗さを求めるから、被測定物の材質・形状等の測定面の影響を受けることなく非接触式により被測定物の表面粗さを測定することができ、被測定物の表面に傷つけることがなく、測定者の経験によらず一定の精度で表面粗さの測定をすることができる効果がある。
【００７０】
また、本発明は、被測定物の表面に法線方向から基準角度傾けてレーザ光を照射するように設けたレーザ投光機と、前記レーザ光の反射光である粒状斑点模様を撮像するように前記被測定物の表面に対向する向きに設けた撮像機と、レーザ光の前記被測定物への照射点を中心に前記レーザ投光機と前記撮像機を結ぶ方向に前記被測定物を前記レーザ投光機と前記撮像機に対して相対的に偏向させることによりレーザ光の照射角度を前記基準角度から変化させる照射角度調整機構と、レーザ光を前記基準角度から照射したときの粒状斑点模様である基準粒状斑点模様を基準にして、レーザ光の照射角度を前記基準角度から変化させたときの粒状斑点模様である変化粒状斑点模様の変化を測定することにより前記被測定物の表面粗さを求める画像処理装置とからなる構成を有することにより、被測定物をレーザ投光機と撮像機に対して相対的に偏向させることによりレーザ光の被測定物への照射角度を変化させることができると共に、前記被測定物を偏向させることによってもレーザ光の照射角度を前記基準角度から変化させることができるから、照射角度調整機構の構造を簡素化することができる効果がある。
【００７１】
また、本発明は、前記画像処理装置が、レーザ光の各照射角度において前記基準粒状斑点模様と前記変化粒状斑点模様の変化量を算出し、該変化量から変化率（変化量／照射角度の変化量）を算出することにより前記被測定物の表面粗さを求めるようにした請求項１１又は１２に記載の構成を有することにより、被測定物の表面粗さを前記変化率によって数値的に表すことができるから、客観的に被測定物の表面粗さを比較することができる効果がある。
【００７２】
また、本発明は、前記基準粒状斑点模様と前記変化粒状斑点模様の変化量が、前記基準粒状斑点模様と前記変化粒状斑点模様の一致度の変化量である請求項１３に記載の構成を有することにより、基準粒状斑点模様と変化粒状斑点模様の一致度によっても粒状斑点模様の変化を測定することができ、被測定物の表面粗さを求めることができる効果がある。
【００７３】
また、本発明は、前記画像処理装置が、前記基準粒状斑点模様と前記変化粒状斑点模様の一致度の変化を前記変化粒状斑点模様の移動距離の関数で表し、該関数の係数から前記被測定物の表面粗さを求めるようにした請求項１４に記載の構成を有することにより、前記関数の係数からレーザ光照射部分の２乗平均表面粗さを求めることができ、被測定物の表面粗さを直接的に求めることができる効果がある。
【００７４】
また、本発明は、前記画像処理装置が、前記関数の一次の項の係数から前記被測定物の表面粗さを求めるようにした請求項１５に記載の構成を有することにより、表面粗さが増す毎に前記関数の一次の項の係数の絶対値が大きくなるという関係があるから、前記関数の一次の項の係数によって測定物の表面粗さを直接的に求めることができる効果がある。
【００７５】
また、本発明は、前記画像処理装置が、予め測定した表面粗さが既知である複数の標準片の標準変化率を記憶する記憶装置を有し、前記被測定物の前記変化率を前記標準変化率と比較照合して、前記被測定物の表面粗さを求めるようにした請求項１３又は１４に記載の構成を有することにより、被測定物の変化率に最も近い標準片の標準変化率を選び出すことにより、被測定物の表面粗さを標準片の表面粗さにより表すことができると共に、表面粗さが増す毎に変化率が大きくなるという関係から各標準片の表面粗さの中間値も表すことができる効果がある。
【００７６】
また、本発明は、前記画像処理装置は、撮像した前記粒状斑点模様を相関法により画像処理する相関処理機能を有し、この相関処理機能により前記基準粒状斑点模様に対する前記変化粒状斑点模様の変化を測定するようにした請求項１１乃至１７のいずれかに記載の構成を有することにより、撮像した前記粒状斑点模様を相関法により画像処理することにより、容易に変化粒状斑点模様の変化を測定することができる効果がある。
【００７７】
また、本発明は、前記相関法が位相限定相関法であり、前記粒状斑点模様の輪郭画像により前記基準粒状斑点模様に対する前記変化粒状斑点模様の変化を測定するようにした請求項１８に記載の構成を有することにより、位相限定相関法により画像処理し、前記粒状斑点模様のフーリエ変換の位相成分に対応する輪郭画像のみを比較するから、レーザ光の照度や被測定物の反射率等の違いによる粒状斑点模様の明暗レベルの変動によって測定誤差を生じないと共に、粒状斑点模様のデータ量が少なくなるので演算速度が早くなり、表面粗さの測定時間を短くすることができる効果がある。
【００７８】
また、本発明は、前記撮像機が、ＣＣＤ素子と、該ＣＣＤ素子の前方に設けた外来光を遮断する暗視筒とからなる請求項１１乃至１９のいずれかに記載の構成を有することにより、ＣＣＤ素子によりレーザ光の反射光である粒状斑点模様を直接撮像することができ、暗視筒により周囲が明るい場所でも粒状斑点模様を撮像することができる効果がある。
【図面の簡単な説明】
【図１】 本発明に係るレーザ反射光による表面粗さ測定装置の第一実施例を示す構成図
【図２】 第一実施例の要部を示す概略正面図
【図３】 第一実施例の詳細を示すＡ部拡大図
【図４】 本測定装置の原理を示す概略正面図
【図５】 第二実施例を示す構成図
【図６】（ａ）粒状斑点模様の撮像図
（ｂ）粒状斑点模様の相関関数を示す斜視図
【図７】 第一実施例の表面粗さの測定結果を示す図
【図８】 第一実施例の表面粗さの測定結果を示す図
【図９】 第一実施例の表面粗さの測定結果を示す図
【図１０】 第二実施例の表面粗さの測定結果を示す図
【図１１】 第二実施例の表面粗さの測定結果を示す図
【図１２】 第二実施例の表面粗さの測定結果を示す図
【図１３】 第二実施例の表面粗さの測定結果を示す図
【符号の説明】
１ レーザ投光機
２ 照射角度調整機構
３ ＣＣＤカメラ
４ 画像処理装置
５ 表示出力装置
６ 印字出力装置
７ 位相限定相関処理装置
８ 画像処理用コンピュータ
９ 被測定物
１０ 照射点
１１ａ 基準粒状斑点模様
１１ｂ 変化粒状斑点模様
１２ 回転軸
１３ 保持部材
１４ 支持部材
１５ ステッピングモータ
１６ 固定器具
１７ ＣＣＤ素子
１８ 暗視筒
１９ 照射角度調整機構[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a non-contact type surface roughness measuring method, and relates to a surface roughness measuring method using laser reflected light and an apparatus therefor.
[0002]
[Prior art]
Conventionally, methods for measuring the surface roughness of an object to be measured include a method using visual comparison and a contact needle method.
Visual comparison and collation are performed by visual comparison of the surface roughness standard piece for comparison and the surface of the object to be measured, and a reference surface that seems to be closest to the surface of the object to be measured is selected from the surface roughness standard piece for comparison. The roughness number of the reference surface is the surface roughness of the object to be measured. The contact needle method uses a diamond needle as a contact needle and scans the surface of the object to be measured by applying a constant contact pressure, thereby directly measuring the surface roughness of the object to be measured. It measures roughness and is widely used.
[0003]
[Problems to be solved by the invention]
However, since the visual comparison and collation is based on human vision, the experience of the measurer is required, and the measurement accuracy of the surface roughness varies depending on the measurer.
In the contact needle method, the surface of the object to be measured may be damaged particularly when the surface of the object to be measured is soft in order to bring the contact needle into contact with the surface of the object to be measured. Furthermore, even if the surface of the object to be measured is hard, a measurement error due to wear of the contact needle occurs, or the contact needle jumps over the irregularities on the surface of the object to be measured depending on measurement conditions such as scanning speed and contact pressure. There was a problem that a measurement error occurred.
[0004]
In addition, as a measurement method that does not damage the surface of the object to be measured, there is a non-contact light wave interference method, but the optical system is complex, and the reflectivity depends on the material and surface shape of the object to be measured. Due to the difference in measurement, the measurement results are greatly affected, and there is a problem that the measurement object cannot be used for different materials and shapes.
[0005]
[Means for Solving the Problems]
Therefore, in order to solve the above problems, the present invention irradiates a laser beam onto the surface of the object to be measured by tilting the laser projector by a reference angle from the normal direction of the surface of the object to be measured, By irradiating the laser beam while changing the irradiation angle of the laser beam from the reference angle by deflecting the laser projector in the tilt direction around the irradiation point of the object to be measured, The granular spot pattern which is the reflected light of the laser beam is imaged by an imaging device fixed in a direction facing the surface, and the reference granular spot pattern which is a granular spot pattern when the laser beam is irradiated from the reference angle is used as a reference. Measuring the surface roughness of the object to be measured by measuring the change in the granular spot pattern, which is a granular spot pattern when the irradiation angle of the laser beam is changed from the reference angle. It is to provide a method.
According to the present invention, the granular spot pattern, which is the reflected light of the laser beam, is changed by irradiating the laser beam while changing the irradiation angle of the laser beam from the reference angle, due to the difference in the surface roughness of the object to be measured. Since the rate of change is different, the surface roughness of the object to be measured is determined by this change in the granular spot pattern, so the object to be measured can be measured in a non-contact manner without being affected by the measurement surface such as the material and shape of the object to be measured. The surface roughness of the object can be measured, the surface of the object to be measured is not damaged, and the surface roughness can be measured with a certain accuracy regardless of the experience of the measurer.
[0006]
The present invention also irradiates the laser light onto the surface of the object to be measured while tilting the laser projector at a reference angle from the normal direction of the surface of the object to be measured, and in a direction facing the surface of the object to be measured. The spotted spot pattern which is the reflected light of the laser beam is imaged by the provided imaging device, and then in the direction connecting the laser projector and the imaging device around the irradiation point of the laser beam to the object to be measured By deflecting the object to be measured relative to the laser projector and the imaging device, the laser beam is irradiated while changing the laser beam irradiation angle from the reference angle, and the laser beam is irradiated from the reference angle. By measuring the change of the granular spotted pattern that is the granular spotted pattern when the irradiation angle of the laser beam is changed from the reference angle on the basis of the reference granular spotted pattern that is the granular spotted pattern when irradiated Table of measured objects Surface roughness measuring method according to the reflected laser beam to determine the roughness is to provide.
According to the present invention, it is possible to change the irradiation angle of the laser beam to the object to be measured by deflecting the object to be measured relative to the laser projector and the imaging device, and to change the object to be measured. Also by deflecting, the irradiation angle of the laser beam can be changed from the reference angle, and the irradiation angle of the laser beam can be easily changed.
[0007]
3. The method according to claim 1, wherein the direction of the imaging device facing the surface of the object to be measured is a substantially normal direction of the surface of the object to be measured. Is to provide.
According to the present invention, since the granular spotted pattern can be imaged without being affected by the blind spot due to the unevenness of the surface of the object to be measured, the surface roughness can be accurately measured.
[0008]
Further, the present invention calculates a change amount of the reference granular spot pattern and the change granular spot pattern at each irradiation angle of the laser beam, and calculates a change rate (change amount / change amount of the irradiation angle) from the change amount. The surface roughness measurement method using laser reflected light according to any one of claims 1 to 3, wherein the surface roughness of the object to be measured is obtained.
[0009]
5. The laser reflected light according to claim 4, wherein the amount of change between the reference granular spotted pattern and the changed granular spotted pattern is the amount of change in the degree of coincidence between the reference granular spotted pattern and the changed granular spotted pattern. The method for measuring the surface roughness according to the above is provided.
According to the present invention, it is possible to measure the change of the granular spotted pattern based on the degree of coincidence between the reference granular spotted pattern and the changed granular spotted pattern, and the surface roughness of the object to be measured can be obtained from the amount of change in the degree of coincidence. .
[0010]
Further, the present invention represents a change in the degree of coincidence between the reference granular spotted pattern and the changed granular spotted pattern as a function of a moving distance of the changed granular spotted pattern, and the surface roughness of the object to be measured is calculated from a coefficient of the function. The surface roughness measuring method using laser reflected light according to claim 5 is obtained.
According to the present invention, the root mean square surface roughness of the laser light irradiated portion can be obtained from the coefficient of the function, and the surface roughness of the object to be measured can be directly obtained.
[0011]
The present invention also provides a surface roughness measuring method using laser reflected light according to claim 6, wherein the surface roughness of the object to be measured is obtained from a coefficient of a first-order term of the function.
According to the present invention, since the absolute value of the coefficient of the first-order term of the function increases as the surface roughness increases, the surface roughness of the measurement object is directly determined by the coefficient of the first-order term of the function. Can be obtained.
[0012]
In addition, the present invention measures in advance the standard change rate of a plurality of standard pieces whose surface roughness is known, and compares and compares the measured change rate of the measured object with the standard change rate. The surface roughness measurement method using laser reflected light according to claim 4 or 5, wherein the surface roughness of a measurement object is obtained.
According to the present invention, by selecting the standard change rate of the standard piece closest to the change rate of the object to be measured, the surface roughness of the object to be measured can be expressed by the surface roughness of the standard piece, and the surface roughness. The intermediate value of the surface roughness of each standard piece can also be expressed from the relationship that the rate of change increases with each increase.
[0013]
The laser reflected light according to any one of claims 1 to 8, wherein the image processing is performed on the captured granular spotted pattern by a correlation method, and a change in the changed granular spotted pattern with respect to the reference granular spotted pattern is measured. The method for measuring the surface roughness according to the above is provided.
According to the present invention, it is possible to easily measure the change of the changed granular spot pattern by subjecting the captured granular spot pattern to image processing by the correlation method.
[0014]
The laser reflected light according to claim 9, wherein the correlation method is a phase-only correlation method, and a change in the change granular spotted pattern with respect to the reference granular spotted pattern is measured from an outline image of the granular spotted pattern. The method for measuring the surface roughness according to the above is provided.
According to the present invention, since image processing is performed by the phase-only correlation method and only the contour image corresponding to the phase component of the Fourier transform of the granular spotted pattern is compared, the difference in the illuminance of the laser light, the reflectance of the object to be measured, etc. Measurement error is not caused by the fluctuation of the brightness level of the granular spot pattern, and the amount of data of the granular spot pattern is reduced, so that the calculation speed is increased and the measurement time of the surface roughness can be shortened.
[0015]
The present invention also provides a laser projector provided to irradiate the surface of the object to be measured with a reference angle inclined from the normal direction and a laser light irradiation point on the object to be measured. An irradiation angle adjusting mechanism that changes the irradiation angle of the laser beam from the reference angle by deflecting the laser projector in the tilt direction, and the object to be measured so as to image a granular spot pattern that is a reflected light of the laser beam The reference angle of the laser beam is determined with reference to an image pickup device fixed in a direction facing the surface of the surface and a reference granular spot pattern which is a granular spot pattern when the laser beam is irradiated from the reference angle. Provided is a surface roughness measuring device using laser reflected light, which comprises an image processing device for determining the surface roughness of the object to be measured by measuring a change in the changed granular spot pattern, which is a granular spot pattern when changed from Than it is.
According to the present invention, the granular spot pattern, which is the reflected light of the laser beam, is changed by irradiating the laser beam while changing the irradiation angle of the laser beam from the reference angle, due to the difference in the surface roughness of the object to be measured. Since the change speed is different, the surface roughness of the object to be measured is obtained by this change in the granular spot pattern, so that the object to be measured can be measured in a non-contact manner without being affected by the measurement surface such as the material and shape of the object to be measured. The surface roughness of the object can be measured, the surface of the object to be measured is not damaged, and the surface roughness can be measured with a certain accuracy regardless of the experience of the measurer.
[0016]
Further, the present invention captures a laser projector provided to irradiate the surface of the object to be measured with a laser beam inclined at a reference angle from the normal direction, and a granular spot pattern that is reflected light of the laser beam. An imaging device provided in a direction facing the surface of the object to be measured, and the object to be measured in a direction connecting the laser projector and the imager with a laser beam irradiated to the object to be measured. An irradiation angle adjustment mechanism for changing the irradiation angle of the laser beam from the reference angle by deflecting the laser projector and the imaging device relative to each other, and granular spots when the laser beam is irradiated from the reference angle The surface roughness of the object to be measured is measured by measuring a change in the granular spotted pattern, which is a granular spotted pattern when the irradiation angle of the laser beam is changed from the reference angle on the basis of the reference granular spotted pattern that is a pattern. Image to ask for There is provided a surface roughness measuring device according to the reflected laser beam comprising the management device.
According to the present invention, it is possible to change the irradiation angle of the laser beam to the object to be measured by deflecting the object to be measured relative to the laser projector and the imaging device, and to change the object to be measured. Since the irradiation angle of the laser beam can be changed from the reference angle also by deflecting, the structure of the irradiation angle adjusting mechanism can be simplified.
[0017]
Further, according to the present invention, the image processing apparatus calculates a change amount of the reference granular spot pattern and the change granular spot pattern at each irradiation angle of the laser beam, and a change rate (change amount / irradiation angle of the change amount / irradiation angle) is calculated from the change amount. The surface roughness measuring device using laser reflected light according to claim 11 or 12, wherein the surface roughness of the object to be measured is calculated by calculating (amount of change).
[0018]
Further, according to the present invention, the amount of change between the reference granular spotted pattern and the changed granular spotted pattern is the amount of change in the degree of coincidence between the reference granular spotted pattern and the changed granular spotted pattern. A surface roughness measuring device is provided.
According to the present invention, the change of the granular spot pattern can be measured also by the degree of coincidence between the reference granular spot pattern and the changed granular spot pattern, and the surface roughness of the object to be measured can be obtained.
[0019]
Further, in the present invention, the image processing device represents a change in the degree of coincidence between the reference granular spotted pattern and the changed granular spotted pattern as a function of a moving distance of the changed granular spotted pattern, and the measured value is calculated from a coefficient of the function. The surface roughness measuring apparatus using laser reflected light according to claim 14, wherein the surface roughness of an object is obtained.
According to the present invention, the root mean square surface roughness of the laser light irradiated portion can be obtained from the coefficient of the function, and the surface roughness of the object to be measured can be directly obtained.
[0020]
Further, the present invention provides the surface roughness measuring apparatus using laser reflected light according to claim 15, wherein the image processing apparatus obtains the surface roughness of the object to be measured from the coefficient of the first-order term of the function. It is to provide.
According to the present invention, since the absolute value of the coefficient of the first-order term of the function increases as the surface roughness increases, the surface roughness of the measurement object is directly determined by the coefficient of the first-order term of the function. Can be obtained.
[0021]
The image processing apparatus may further include a storage device that stores a standard change rate of a plurality of standard pieces whose surface roughness measured in advance is known, and the change rate of the object to be measured is the standard change rate. The surface roughness measuring device by laser reflected light according to claim 13 or 14, wherein the surface roughness of the object to be measured is obtained by comparison with a change rate.
According to the present invention, by selecting the standard change rate of the standard piece closest to the change rate of the object to be measured, the surface roughness of the object to be measured can be expressed by the surface roughness of the standard piece, and the surface roughness. The intermediate value of the surface roughness of each standard piece can also be expressed from the relationship that the rate of change increases with each increase.
[0022]
Further, according to the present invention, the image processing apparatus has a correlation processing function of performing image processing on the captured granular spotted pattern by a correlation method, and the correlation processing function changes the change granular spotted pattern with respect to the reference granular spotted pattern. An apparatus for measuring surface roughness using laser reflected light according to any one of claims 11 to 17 is provided.
According to the present invention, it is possible to easily measure the change of the changed granular spot pattern by subjecting the captured granular spot pattern to image processing by the correlation method.
[0023]
Further, in the present invention, the correlation method is a phase-only correlation method, and a change in the change granular spotted pattern with respect to the reference granular spotted pattern is measured from an outline image of the granular spotted pattern. An apparatus for measuring surface roughness using laser reflected light is provided.
According to the present invention, since image processing is performed by the phase-only correlation method and only the contour image corresponding to the phase component of the Fourier transform of the granular spotted pattern is compared, the difference in the illuminance of the laser light, the reflectance of the object to be measured, etc. Measurement error is not caused by the fluctuation of the brightness level of the granular spot pattern, and the amount of data of the granular spot pattern is reduced, so that the calculation speed is increased and the measurement time of the surface roughness can be shortened.
[0024]
The surface of the laser reflected light according to any one of claims 11 to 19, wherein the imaging device comprises a CCD element and a night vision tube provided in front of the CCD element for blocking external light. A roughness measuring device is provided.
According to the present invention, a granular spot pattern, which is reflected light of laser light, can be directly imaged by a CCD element, and a granular spot pattern can be imaged even in a bright place by a night vision tube.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described based on examples shown in the drawings.
In the embodiment shown in FIG. 1 or FIG. 2, the apparatus for measuring the surface roughness by the laser reflected light according to the present invention is provided so as to irradiate the surface of the object 9 with the laser light inclined at the reference angle θs from the normal direction. The laser projector 1 and the irradiation angle for changing the laser light irradiation angle from the reference angle θs by deflecting the laser projector 1 in the tilt direction around the irradiation point 10 of the laser light to the object 9 to be measured. The adjustment mechanism 2, the CCD camera 3 that is an imaging device fixed in a direction facing the surface of the object 9 to be imaged so as to capture a granular spot pattern that is reflected light of the laser light, and the laser light at a reference angle Using the reference granular spot pattern 11a, which is a granular spot pattern when irradiated from θs, as a reference, changes in the changed granular spot pattern 11b, which is a granular spot pattern, when the laser light irradiation angle is changed from the reference angle θs are measured. To do It is constituted from the image processing device 4 for obtaining the more the surface roughness of the object 9.
[0026]
The surface roughness measuring apparatus using laser reflected light according to the present invention measures the surface roughness of the object 9 to be measured based on the following basic principle.
As shown in FIG. 3, when the measurement object 9 is irradiated with laser light, the laser light is irregularly reflected by the unevenness of the surface of the measurement object 9, and a granular spot pattern is generated due to interference. When irradiation is performed while changing the irradiation angle from the reference angle θs by a minute angle δθ with the position of the laser light irradiation point 10 fixed, as shown in FIG. 6A, a granular spot pattern is formed according to the change in the irradiation angle. Has a property that the shape of the granular spotted pattern is changed as the pattern moves. The degree of change in the granular spotted pattern has a relationship that it increases as the average height h of the irregularities on the surface of the DUT 9 increases.
[0027]
At this time, as shown in FIG. 4, the reference granular spotted pattern 11a when the laser light is irradiated from the laser projector 1 at the reference angle θs, and the change granularity when the irradiation angle of the laser light is inclined by a minute angle δθ. When the correlation of the speckled pattern 11b is taken, the maximum value C of the cross-correlation function ₁₂ The relationship between (Ax) and the position Ax of the maximum value is expressed as shown in Equation 1 except for the proportionality coefficient.
[0028]
[Expression 1]

[0029]
In Equation 1, σ _h Is the square surface roughness of the surface of the object 9 to be measured, k (= 2π / λ) is the wave number, θ ₀ Is the angle formed between the normal direction of the surface of the object 9 to be measured and the imaging direction of the CCD element 17, L ₀ Indicates the distance between the laser beam irradiation point 10 and the CCD element 17. The maximum value position Ax is expressed as shown in Equation 2, and means the moving distance of the granular spotted pattern due to the change δθ in the irradiation angle of the laser beam.
[0030]
[Expression 2]

[0031]
As shown in FIG. 4, when the autocorrelation of the reference granular spot pattern 11a when the laser beam is irradiated at the reference angle θs and the result is displayed three-dimensionally, the maximum value is shown at the center as shown in FIG. 6B. C ₁₁ It becomes the shape which has.
Next, the cross-correlation between the changed granular spotted pattern 11b and the reference granular spotted pattern 11a when the irradiation angle of the laser beam is changed by δθ is taken, and the result is displayed three-dimensionally, as shown in FIG. 6 (b). The position of the maximum value moves by Ax, and the maximum value C ₁₂ Is the maximum value C ₁₁ A more reduced shape. This maximum value C ₁₂ Paying attention to the maximum value C of the autocorrelation function ₁₁ Value of the cross-correlation function for C ₁₂ The degree of coincidence is expressed as a percentage.
The movement distance (Ax) of the position of the maximum value of the cross-correlation function indicates the movement amount of the granular spot pattern, and corresponds to the change in the irradiation angle of the laser beam.
In the apparatus for measuring surface roughness by laser reflected light according to the present invention, the surface roughness of the object to be measured 9 is obtained from the degree of coincidence change representing the change in coincidence with respect to the movement distance (Ax). .
[0032]
Note that the surface roughness of the object to be measured is obtained by calculating the amount of change between the reference granular spotted pattern 11a and the changed granular spotted pattern 11b, and calculating the rate of change (the amount of change / the amount of change in the irradiation angle) from the amount of change. It is also possible.
Here, the amount of change between the reference granular spot pattern 11a and the change granular spot pattern 11b refers to the outline of the granular spot pattern or the amount of change between the outline and shading, and as described above, the reference granular spot pattern 11a and the change granular spot pattern 11b is taken, the maximum value C of the cross-correlation function ₁₂ It is represented by the difference.
[0033]
For the calculation of the correlation function, a conjugate product of the Fourier transform of each image of the granular spotted pattern is taken and can be obtained by Fourier transform. Alternatively, instead of taking the conjugate product of the Fourier transform, a phase only correlation method using only the phase portion of the Fourier transform can be used. In the illustrated embodiment, the correlation function is obtained using the phase-only correlation method, and the configuration of the measurement apparatus using the phase-only correlation method will be described.
[0034]
In the embodiment shown in FIG. 1 or FIG. 2, the laser projector 1 is composed of a laser element, a cooling circuit, a drive circuit, and a lens, and in order to draw a stable granular spotted pattern on the object 9 to be measured, The surface of the object to be measured 9 is irradiated with laser light having high brightness, directivity, and interference.
In the illustrated embodiment, the laser projector 1 uses red light having a wavelength of 670 nm and an output of 4 mW, and emits parallel light. The lens of the laser projector 1 is provided so that the beam diameter of the irradiated laser beam can be changed, and is configured so that the average surface roughness in the region irradiated with the laser beam can be directly obtained. is there. Further, during the measurement of the surface roughness, the beam diameter of the laser beam to be irradiated can be fixed in order to keep the size of the granular spotted pattern constant.
The laser light is not limited to parallel light, and either convergent light or divergent light can be used.
[0035]
As shown in FIG. 2, the irradiation angle adjusting mechanism 2 includes a rotating shaft 12, a holding member 13 that holds the laser projector 1, and a support member 14 that supports the holding member 13 on the rotating shaft 12.
The holding member 13 is provided so as to hold the laser projector 1 so that the irradiation point 10 on the extension line of the axis center of the rotating shaft 12 can be irradiated with laser light. With this configuration, the irradiation point 10 can always be irradiated with the laser beam even if the laser projector 1 is deflected by rotating about the rotation shaft 12, and the projector 1 and the irradiation point 10 can be irradiated. The irradiation angle of the laser beam can be changed in a state where the distance is kept constant. Therefore, the change of the granular spot pattern due to the change in the distance between the projector 1 and the irradiation point 10 can be prevented, and the change of the granular spot pattern due to the change of the irradiation angle of the laser beam can be measured.
[0036]
In addition, a stepping motor 15 is provided on the rotary shaft 12, and the direction of the laser projector 1 can be deflected by rotating the rotary shaft 12 by a minute angle δθ. Since the rotation means of the rotary shaft 12 can be stably rotated, it is preferable to use a stepping motor. However, since the value of the angle δθ is not necessarily required when determining the surface roughness, the rotation means It can also be rotated by a servo motor that can easily adjust the angle, and can be fixed by rotating by a minute angle δθ by a ratchet mechanism.
Reference numeral 16 denotes a fixing device for fixing the object 9 to be measured. In the illustrated embodiment, the surface roughness measurement point of the object 9 to be measured is fixed to the irradiation point 10 by using an XY stage. I can do it.
[0037]
The CCD camera 3 includes a CCD device (Charge Coupled Device) 17 and a night vision tube 18 provided in front of the CCD device 17 for blocking external light. It is configured to take an image.
Further, the CCD camera 3 takes an image of a granular spot pattern drawn on the object to be measured 9 by the CCD element 17 and outputs it to the image processing device 4 as an analog signal.
[0038]
Further, as shown in FIG. 1 or FIG. 2, the CCD camera 3 is fixed in the normal direction of the surface of the object 9 to be measured. Since the granular spotted pattern can be imaged without being affected by the blind spot due to the unevenness of the surface of the object 9 to be measured, and the surface roughness can be measured with high accuracy, the CCD camera 3 is attached to the surface of the object 9 to be measured. Although it is most preferable to provide in the normal direction, it is not limited to the normal direction of the surface of the object 9 to be measured, and the CCD camera is oriented in the direction facing the surface of the object 9 so that a granular spot pattern can be imaged. 3 is sufficient. For example, as shown in FIG. 4, the CCD camera 3 is moved at an angle θ from the normal direction of the surface of the object 9 to be measured. ₀ The irradiation point 10 can also be provided so as to be tilted only.
[0039]
In the embodiment shown in FIG. 1 or 2, the image processing device 4 includes a phase-only correlation processing device 7 having a phase-only correlation processing function and an image processing computer 8, and a reference granular spot imaged by the CCD camera 3. The maximum value C of the cross-correlation function is obtained by correlating the pattern 11a with the change granular spotted pattern 11b at each irradiation angle. ₁₂ The maximum value C of the auto-correlation function of the reference granular spotted pattern 11a ₁₁ The degree of coincidence of the granular spot pattern is calculated as compared with the above, and the surface roughness of the object to be measured 9 is obtained from the change in the degree of coincidence at each irradiation angle.
[0040]
The phase only correlation processing device 7 is configured by a super integrated circuit (VLSI), and includes an A / D conversion unit, a Fourier transform unit, and a control unit (not shown).
The A / D conversion unit converts the granular spotted pattern analog signal sent from the CCD camera 3 into a digital signal and sends it to the Fourier transform unit.
The Fourier transform unit performs two-dimensional discrete Fourier transform (DFT) on the digital signal image data, and transforms the image data into the frequency domain to thereby generate an amplitude component (grayscale data) and a phase component (image contour data). ). As described above, the control unit is configured to extract only the phase component from the Fourier-transformed image data and correlate the reference granular spotted pattern 11a and the changed granular spotted pattern 11b.
[0041]
Since the phase-only correlation processing device 7 uses only the phase component of the Fourier transform of the image data to correlate the reference granular spotted pattern 11a and the changed granular spotted pattern 11b, the illuminance difference of the laser beam and the object to be measured The surface roughness can be measured without being affected by the brightness and darkness of the granular speckled pattern due to the reflectance of the surface of 9 and processing is performed more than the calculation by the conventional program by causing the super-integrated circuit to perform correlation processing. Can be speeded up, and the measurement time of the surface roughness can be shortened.
Note that the control unit is not limited to extracting only the phase component of the Fourier transform of the image, and suppresses the amplitude by suppressing processing such as log processing and √ processing, thereby reducing the data amount and giving the phase component a weight. It is also possible to take a correlation between the reference granular spotted pattern 11a and the changed granular spotted pattern 11b.
[0042]
In the embodiment shown in FIG. 1, the image processing computer 8 represents the degree of coincidence at each irradiation angle in correspondence with the movement distance Ax of the granular spot pattern.
As shown in FIGS. 7 to 9, the horizontal axis represents the movement distance Ax (μm) of the granular spot pattern, and the vertical axis represents the degree of coincidence between the reference granular spot pattern 11a and the changed granular spot pattern 11b. The degree of coincidence calculated by the phase-only correlation processing device 7 at each irradiation angle is plotted. Then, the change in the coincidence with respect to the change in the irradiation angle of the laser beam is averaged by the least square method and expressed as a straight line, and the change rate of the coincidence is calculated by obtaining the inclination of the straight line.
[0043]
The image processing computer 8 has a storage unit, and the storage unit measures the slope of the straight line (standard change rate) obtained by measuring a plurality of comparative surface roughness standard pieces whose surface roughness is known. ) Is stored.
The graphs shown in FIG. 7 to FIG. 9 are the results of measuring the surface roughness of the comparative surface roughness standard piece using this surface roughness measuring apparatus. The slope of roughness number SN-5 is -0.0264, the slope of roughness number SN-8 is -0.0289, the slope of roughness number SN-10 is -0.0351, and the roughness As the number increases (surface roughness increases), the slope of the straight line, which is the standard change rate of coincidence, increases.
From this relationship, the image processing computer 8 compares the matching rate change rate of the device under test 9 with the standard change rate and compares the standard change rate closest to the match rate change rate of the device under test 9. A surface roughness standard piece is selected, and the roughness number of the comparative surface roughness standard piece is obtained as the surface roughness of the object 9 to be measured.
[0044]
In the embodiment shown in FIG. 1, reference numeral 5 denotes a display output device, which can display on the screen measurement results such as the rate of change of the degree of coincidence 9 and the surface roughness obtained by the image processing device 4. I can do it.
Reference numeral 6 denotes a print output device, which can print the measurement results such as the rate of change in the degree of coincidence of the object to be measured 9 and the surface roughness obtained by the image processing device 4 on paper, film or the like. is there.
[0045]
The surface roughness of the object to be measured is measured as follows by the surface roughness measuring apparatus using the laser reflected light configured as described above.
As shown in FIG. 1, a measurement location for measuring the surface roughness of the device under test 9 is selected, and the device under test 9 is fixed to the fixture 16 by aligning the measurement site with the laser light irradiation point 10. Then, the laser projector 1 is tilted by the reference angle θs from the normal direction of the surface of the object 9 to be measured by the irradiation angle adjusting mechanism 2 to irradiate the surface of the object 9 with the laser light, and with the reflected light of the laser light. A certain granular spotted pattern is imaged by the CCD camera 3.
The granular spot pattern imaged by the CCD camera 3 is sent to the phase-only correlation processing device 7, digitized image data, and then subjected to two-dimensional discrete Fourier transform (DFT), and the frequency represented by the amplitude and phase. Convert to area. The phase limited processing is performed on the Fourier transformed image data of the reference granular spotted pattern 11 a, and only the phase component is extracted and stored in the phase limited correlation processing device 7.
[0046]
Next, by rotating the irradiation angle adjusting mechanism 2 by the minute angle δθ by the stepping motor 15, the laser projector 1 is tilted by the minute angle δθ in the tilt direction around the irradiation point 10 of the laser beam to the object 9 to be measured. Laser light is irradiated while deflecting each one.
Accordingly, it is possible to fix the position of the irradiation point 10 of the laser beam on the object 9 to be measured, and to set the irradiation angle of the laser beam as a reference while keeping the distance between the laser projector 1 and the irradiation point 10 constant. The laser beam can be irradiated on the surface of the object 9 while changing from the angle θs by the minute angle δθ.
[0047]
As shown in FIG. 6, the granular spot pattern imaged by the CCD camera 3 corresponds to a change in the irradiation angle of the laser beam as shown in FIG. The CCD camera 3 captures an image of a continuous spotted spot pattern.
That is, when the laser beam is irradiated on the surface of the measurement object 9 with the reference angle θs inclined from the normal direction of the surface of the measurement object 9, the reference granular spotted pattern 11a is imaged. Then, the irradiation angle is changed to a minute angle δθ ₁ By changing the angle δθ from the reference granular spotted pattern 11a ₁ The changed granular spotted pattern 11b whose shape has changed to the position moved by the distance Ax corresponding to ₁ Is imaged. Thus, the minute angle δθ ₁ , Δθ ₂ , ..., δθ _n When the irradiation angle is changed, the angle δθ ₁ , Δθ ₂ , ..., δθ _n To the position moved by the distance Ax corresponding to ₀ 11b ₁ ... 11b _n Is imaged.
[0048]
And the change granular spotted pattern 11b imaged with CCD camera 3 in each irradiation angle. ₁ 11b ₂ ... 11b _n Is sent to the phase-only correlation processing device 7 in the same way as the reference granular spotted pattern 11a, digitizes the image data, and then performs a two-dimensional discrete Fourier transform (DFT) to represent a frequency region represented by amplitude and phase. Convert to
A phase limiting process is performed on the Fourier transformed image data of the changed granular spotted pattern 11b to extract only the phase component.
By correlating the image data of the changed granular spotted pattern 11b subjected to the phase limiting process and the image data of the reference granular spotted pattern 11a subjected to the phase limiting process stored in the phase limited correlation processing device 7, FIG. A cross-correlation function as shown in (b) is obtained. At this time, the maximum value C of the autocorrelation function of the reference granular spotted pattern 11a ₁₁ The cross-correlation function C between the changed granular spotted pattern 11b and the reference granular spotted pattern 11a, where 100 is 100 ₁₂ The maximum value of is the degree of coincidence.
[0049]
Then, the reference granular spotted pattern 11a and the changed granular spotted pattern 11b calculated at each irradiation angle. ₁ 11b ₂ ... 11b _n Are sent to the image processing computer 8.
As shown in FIG. 7 to FIG. 9, the image processing computer 8 has a moving distance Ax (μm) of the granular spot pattern on the horizontal axis and a changed granular spot pattern 11b on the vertical axis. _n And the reference granular spot pattern 11a are plotted, the degree of coincidence is plotted in the figure, the change in the degree of coincidence with respect to the movement distance Ax of the granular spot pattern is averaged by the least square method, and is represented by a straight line. Can be calculated.
[0050]
By the above measurement method, a plurality of comparative surface roughness standard pieces whose surface roughness is known in advance are measured to calculate a standard change rate of coincidence, and are stored in the storage unit of the image processing computer 8. .
Similarly, the change rate of the degree of coincidence calculated by measuring the object 9 is compared with the standard change rate stored in the storage unit, and the comparison of the standard change rate closest to the change rate of the degree of coincidence is performed. By selecting the surface roughness standard piece for use, the roughness number of the comparative surface roughness standard piece can be obtained as the surface roughness of the object 9 to be measured.
[0051]
Next, a second embodiment will be described.
In the embodiment shown in FIG. 5, the apparatus for measuring the surface roughness using the laser reflected light according to the present invention irradiates the surface of the object to be measured 9 with the laser beam so as to be inclined at the reference angle θs from the normal direction. An optical machine 1, an imaging machine 3 provided in a direction facing the surface of the object to be measured 9 so as to image a granular spot pattern which is reflected light of the laser light, and an irradiation point 10 of the laser light on the object to be measured 9 The object 9 to be measured is deflected relative to the laser projector 1 and the image pickup device 3 in the direction connecting the laser projector 1 and the image pickup device 3 with the reference angle θs as the center. When the irradiation angle adjustment mechanism 19 to be changed and the reference granular spot pattern 11a that is a granular spot pattern when the laser light is irradiated from the reference angle θs are used as a reference, the irradiation angle of the laser light is changed from the reference angle θs. Change granular spots that are granular spot patterns It is constituted of an image processing apparatus for determining the surface roughness of the object 9 by measuring the change in like 11b.
[0052]
As shown in FIG. 5, the laser projector 1 irradiates the irradiation point 10 of the measurement object 9 with laser light at a measurement start state with a reference angle θs inclined from the normal direction of the surface of the measurement object 9. The CCD camera 3 is fixed in the normal direction of the surface of the object 9 to be measured.
[0053]
In the embodiment shown in FIG. 5, the irradiation angle adjusting mechanism 19 can rotate the fixing device 16 by a minute angle δθ in the direction connecting the laser projector 1 and the imaging device 3 around the irradiation point 10. A stepping motor 15 is provided, and the laser beam irradiation angle is changed from the reference angle θs by deflecting the measurement object 9 fixed to the fixing device 16.
[0054]
Further, as in the illustrated embodiment, not only when the measured object 9 is deflected and the irradiation angle of the laser beam is changed, but the measured object 9 is fixed, and the imaging device 3 and the laser projector 1 are fixed. It is also possible to change the irradiation angle of the laser light by deflecting the laser projector 1 and the image pickup device 3 integrally in the direction connecting the two.
Alternatively, a plurality of laser projectors 1 having different irradiation angles may be provided, and the laser light irradiation angle may be changed by sequentially switching and irradiating the laser light.
Other configurations are the same as those in the embodiment shown in FIG.
[0055]
Next, a third embodiment will be described.
In the configuration shown in FIG. 1 or FIG. 5, the image processing computer 8 calculates the degree of coincidence between the changed granular spotted pattern 11b and the reference granular spotted pattern 11a, and the degree of coincidence Y is calculated based on the theoretical formula of Formula 1. The change is expressed as a function of the movement distance X, and the surface roughness of the DUT 9 is determined from the coefficient of the function.
The degree of coincidence Y is expressed by a quadratic function of the movement distance X, the movement distance X (μm) of the granular spot pattern on the horizontal axis, and the changed granular spot pattern 11b on the vertical axis. _n And the reference granular spotted pattern 11a are represented as shown in FIGS.
[0056]
As shown in FIGS. 10 to 13, the absolute value of the coefficient of the first-order term of the movement distance X has a relationship that the average height h of the unevenness on the surface of the DUT 9 increases. Using this relationship, the image processing computer 8 is configured to directly determine the surface roughness of the object 9 to be measured from the coefficient of the primary term of the movement distance X.
[0057]
Further, in the embodiment shown in FIG. 1 or FIG. 4, the degree of coincidence is obtained by correlating the reference granular spot pattern 11a including the grayscale data and the changed granular spot pattern 11b without providing the phase-only correlation processing device 7. In addition to the degree of coincidence, the image processing computer 8 calculates the degree of coincidence between the reference granular spotted pattern 11a and the changed granular spotted pattern 11b, the amount of distortion, and the like. It is also possible to configure so as to obtain the surface roughness.
That is, the image processing apparatus 4 recognizes the light and shade of each pixel of the reference granular spot pattern 11a including the light and shade data without performing phase-only correlation processing on the image data, and changes the granular spots sent from the CCD camera 3 The amount of distortion of the reference granular spotted pattern 11a and the changed granular spotted pattern 11b is calculated by comparing the pattern 11b with the recognized shading and calculating the amount changed by the distortion of the granular spotted pattern for each pixel of the CCD element 17. It is also possible to calculate the amount of change such as the surface roughness of the object 9 to be measured.
[0058]
The measurement of the surface roughness of the object to be measured includes the case where the surface of the object to be measured 9 is covered with a transparent substance that transmits laser light.
Further, the surface shape of the object to be measured 9 is not limited to a planar shape as in the illustrated embodiment, and a curved surface shape can also be measured. Furthermore, by narrowing down the diameter of the laser beam to be irradiated, even in the case where the surface shape of the measurement object 9 is complicated, it is possible to perform measurement in a unique region of each part.
[0059]
【The invention's effect】
As described above, according to the surface roughness measurement method using laser reflected light according to the present invention, the laser projector is tilted at a reference angle from the normal direction of the surface of the object to be measured, and the laser light is applied to the surface of the object to be measured. Next, irradiate the laser beam while changing the irradiation angle of the laser beam from the reference angle by deflecting the laser projector in the tilt direction around the irradiation point of the laser beam to the object to be measured. In addition, it is a granular spot pattern when a spotted spot pattern which is reflected light of the laser beam is imaged by an imaging device fixed in a direction facing the surface of the object to be measured, and the laser beam is irradiated from the reference angle. Using the reference granular spot pattern as a reference, the surface roughness of the object to be measured is obtained by measuring the change of the changed granular spot pattern, which is a granular spot pattern when the laser light irradiation angle is changed from the reference angle. Structure Since the surface roughness of the object to be measured is determined by the change in the granular spot pattern, the surface roughness of the object to be measured is measured in a non-contact manner without being affected by the measurement surface such as the material and shape of the object to be measured. The surface roughness of the object to be measured is not damaged and the surface roughness can be measured with a certain accuracy regardless of the experience of the measurer.
[0060]
The present invention also irradiates the laser light onto the surface of the object to be measured while tilting the laser projector at a reference angle from the normal direction of the surface of the object to be measured, and in a direction facing the surface of the object to be measured. The spotted spot pattern which is the reflected light of the laser beam is imaged by the provided imaging device, and then in the direction connecting the laser projector and the imaging device around the irradiation point of the laser beam to the object to be measured By deflecting the object to be measured relative to the laser projector and the imaging device, the laser beam is irradiated while changing the laser beam irradiation angle from the reference angle, and the laser beam is irradiated from the reference angle. By measuring the change of the granular spotted pattern that is the granular spotted pattern when the irradiation angle of the laser beam is changed from the reference angle on the basis of the reference granular spotted pattern that is the granular spotted pattern when irradiated Table of measured objects By having the configuration for obtaining the roughness, the irradiation angle of the laser beam to the measurement object can be changed by deflecting the measurement object relative to the laser projector and the imaging device, and By deflecting the object to be measured, the laser beam irradiation angle can be changed from the reference angle, and the laser beam irradiation angle can be easily changed.
[0061]
According to the present invention, the object to be measured has the configuration according to claim 1 or 2, wherein the direction of the imaging device facing the surface of the object to be measured is a substantially normal direction of the surface of the object to be measured. Since the granular spotted pattern can be imaged without being affected by the blind spot due to the unevenness of the surface, there is an effect that the surface roughness can be accurately measured.
[0062]
Further, the present invention calculates a change amount of the reference granular spot pattern and the change granular spot pattern at each irradiation angle of the laser beam, and calculates a change rate (change amount / change amount of the irradiation angle) from the change amount. By having the configuration according to any one of claims 1 to 3 for determining the surface roughness of the object to be measured, the surface roughness of the object to be measured can be numerically expressed by the rate of change. There is an effect that the surface roughness of the object to be measured can be compared objectively.
[0063]
Moreover, this invention has the structure of Claim 4 whose variation | change_quantity of the said reference | standard granular spotted pattern and the said change granular spotted pattern is the amount of change of the coincidence degree of the said reference | standard granular spotted pattern and the said changed granular spotted pattern. Thus, it is possible to measure the change in the granular spot pattern based on the degree of coincidence between the reference granular spot pattern and the change granular spot pattern, and to obtain the surface roughness of the object to be measured from the amount of change in the degree of coincidence. .
[0064]
Further, the present invention represents a change in the degree of coincidence between the reference granular spotted pattern and the changed granular spotted pattern as a function of a moving distance of the changed granular spotted pattern, and the surface roughness of the object to be measured is calculated from a coefficient of the function. By having the configuration according to claim 5, the root mean square surface roughness of the laser light irradiated portion can be obtained from the coefficient of the function, and the surface roughness of the object to be measured is directly obtained. There is an effect that can.
[0065]
In addition, the present invention has the configuration according to claim 6, wherein the surface roughness of the object to be measured is obtained from the coefficient of the first-order term of the function. Since there is a relationship that the absolute value of the coefficient of the first-order term increases, there is an effect that the surface roughness of the measurement object can be directly obtained by the coefficient of the first-order term of the function.
[0066]
In addition, the present invention measures in advance the standard change rate of a plurality of standard pieces whose surface roughness is known, and compares and compares the measured change rate of the measured object with the standard change rate. By having the configuration according to claim 4 or 5 for determining the surface roughness of the measurement object, the surface roughness of the measurement object is determined by selecting the standard change rate of the standard piece closest to the change rate of the measurement object. In addition to being able to be represented by the surface roughness of the standard piece, there is an effect that the intermediate value of the surface roughness of each standard piece can be represented from the relationship that the rate of change increases as the surface roughness increases.
[0067]
In addition, the present invention has a configuration according to any one of claims 1 to 8, wherein the captured granular spotted pattern is image-processed by a correlation method, and a change in the changed granular spotted pattern with respect to the reference granular spotted pattern is measured. Thus, there is an effect that the change of the changed granular spot pattern can be easily measured by subjecting the captured granular spot pattern to image processing by the correlation method.
[0068]
Further, according to the present invention, the correlation method is a phase-only correlation method, and the change of the change granular spotted pattern with respect to the reference granular spotted pattern is measured by an outline image of the granular spotted pattern. Therefore, since the image processing is performed by the phase-only correlation method and only the contour image corresponding to the phase component of the Fourier transform of the granular spot pattern is compared, the granular spot due to the difference in the illuminance of the laser beam, the reflectance of the object to be measured, etc. There is an effect that a measurement error does not occur due to variation in the brightness level of the pattern, and the data amount of the granular spotted pattern is reduced, so that the calculation speed is increased and the measurement time of the surface roughness can be shortened.
[0069]
Further, according to the apparatus for measuring the surface roughness using the laser reflected light according to the present invention, the laser projector provided so as to irradiate the laser light on the surface of the object to be measured with the reference angle inclined from the normal direction, and the laser light An irradiation angle adjusting mechanism that changes the irradiation angle of the laser beam from the reference angle by deflecting the laser projector in the tilt direction around the irradiation point of the object to be measured, and a reflected light of the laser beam An image pickup device that is fixed in a direction facing the surface of the object to be measured so as to image a certain granular spot pattern, and a reference granular spot pattern that is a granular spot pattern when laser light is irradiated from the reference angle. From an image processing apparatus that obtains the surface roughness of the object to be measured by measuring a change in a granular spotted pattern that is a granular spotted pattern when the irradiation angle of the laser beam is changed from the reference angle as a reference Na By having the configuration, the surface roughness of the object to be measured is obtained by the change in the granular spot pattern, so that the surface roughness of the object to be measured can be measured in a non-contact manner without being affected by the measurement surface such as the material and shape of the object to be measured. The surface roughness of the object to be measured can be measured, and the surface roughness can be measured with a certain accuracy regardless of the experience of the measurer.
[0070]
Further, the present invention captures a laser projector provided to irradiate the surface of the object to be measured with a laser beam inclined at a reference angle from the normal direction, and a granular spot pattern that is reflected light of the laser beam. An imaging device provided in a direction facing the surface of the object to be measured, and the object to be measured in a direction connecting the laser projector and the imager with a laser beam irradiated to the object to be measured. An irradiation angle adjustment mechanism for changing the irradiation angle of the laser beam from the reference angle by deflecting the laser projector and the imaging device relative to each other, and granular spots when the laser beam is irradiated from the reference angle The surface roughness of the object to be measured is measured by measuring a change in the granular spotted pattern, which is a granular spotted pattern when the irradiation angle of the laser beam is changed from the reference angle on the basis of the reference granular spotted pattern that is a pattern. Image to ask for By having a configuration comprising a processing device, the irradiation angle of the laser beam to the measurement object can be changed by deflecting the measurement object relative to the laser projector and the imaging device, Since the irradiation angle of the laser beam can be changed from the reference angle also by deflecting the object to be measured, there is an effect that the structure of the irradiation angle adjusting mechanism can be simplified.
[0071]
Further, according to the present invention, the image processing apparatus calculates a change amount of the reference granular spot pattern and the change granular spot pattern at each irradiation angle of the laser beam, and a change rate (change amount / irradiation angle of the change amount / irradiation angle is calculated from the change amount. The surface roughness of the object to be measured is calculated numerically according to the rate of change by having the configuration according to claim 11 or 12, wherein the surface roughness of the object to be measured is obtained by calculating a change amount). Since it can be expressed, there is an effect that the surface roughness of the object to be measured can be compared objectively.
[0072]
Moreover, this invention has the structure of Claim 13 whose variation | change_quantity of the said reference | standard granular spotted pattern and the said change granular spotted pattern is a variation | change_quantity of the coincidence degree of the said reference | standard granular spotted pattern and the said changed granular spotted pattern. Thus, the change in the granular spot pattern can be measured also by the degree of coincidence between the reference granular spot pattern and the changed granular spot pattern, and the surface roughness of the object to be measured can be obtained.
[0073]
Further, in the present invention, the image processing apparatus represents a change in the degree of coincidence between the reference granular spotted pattern and the changed granular spotted pattern as a function of a moving distance of the changed granular spotted pattern, and based on a coefficient of the function, the measured object The structure according to claim 14, wherein the surface roughness of the object can be obtained, whereby the root mean square surface roughness of the laser light irradiated portion can be obtained from the coefficient of the function, and the surface roughness of the object to be measured is obtained. There is an effect that can be obtained directly.
[0074]
Further, according to the present invention, the image processing apparatus has the configuration according to claim 15, wherein the surface roughness is obtained from the coefficient of the first-order term of the function. Since there is a relationship that the absolute value of the coefficient of the first-order term of the function increases with each increase, there is an effect that the surface roughness of the measurement object can be directly obtained by the coefficient of the first-order term of the function.
[0075]
In the present invention, the image processing apparatus further includes a storage device that stores a standard change rate of a plurality of standard pieces whose surface roughness measured in advance is known, and the change rate of the object to be measured is the standard change rate. The standard change rate of the standard piece closest to the change rate of the object to be measured is obtained by having the configuration according to claim 13 or 14, wherein the surface roughness of the object to be measured is obtained by comparison with a change rate. The surface roughness of the object to be measured can be expressed by the surface roughness of the standard piece and the rate of change increases as the surface roughness increases. There is an effect that the value can also be expressed.
[0076]
Further, according to the present invention, the image processing apparatus has a correlation processing function of performing image processing on the captured granular spotted pattern by a correlation method, and the correlation processing function changes the change granular spotted pattern with respect to the reference granular spotted pattern. By measuring the image of the captured granular spotted pattern using the correlation method, the change in the changed granular spotted pattern can be easily measured by having the configuration according to any one of claims 11 to 17. There is an effect that can.
[0077]
Further, in the present invention, the correlation method is a phase-only correlation method, and a change in the change granular spotted pattern with respect to the reference granular spotted pattern is measured from an outline image of the granular spotted pattern. By having a configuration, image processing is performed by the phase-only correlation method, and only the contour image corresponding to the phase component of the Fourier transform of the granular spotted pattern is compared, so the difference in the illuminance of the laser light, the reflectance of the object to be measured, etc. As a result, a measurement error does not occur due to the fluctuation of the brightness level of the granular spot pattern, and the amount of data of the granular spot pattern is reduced, so that the calculation speed is increased and the measurement time of the surface roughness can be shortened.
[0078]
Further, according to the present invention, the image pickup device has a configuration according to any one of claims 11 to 19 including a CCD element and a night vision tube provided in front of the CCD element for blocking external light. In addition, it is possible to directly image a granular spot pattern which is reflected light of a laser beam by a CCD element, and to capture a granular spot pattern even in a bright place by a night vision tube.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing a first embodiment of a surface roughness measuring apparatus using laser reflected light according to the present invention.
FIG. 2 is a schematic front view showing the main part of the first embodiment.
FIG. 3 is an enlarged view of part A showing details of the first embodiment.
FIG. 4 is a schematic front view showing the principle of this measuring apparatus.
FIG. 5 is a block diagram showing a second embodiment.
FIG. 6A is an image of a granular spot pattern.
(B) Perspective view showing correlation function of granular spotted pattern
FIG. 7 is a diagram showing the measurement results of the surface roughness of the first example.
FIG. 8 is a diagram showing the measurement results of the surface roughness of the first example.
FIG. 9 is a diagram showing the measurement results of the surface roughness of the first example.
FIG. 10 is a diagram showing the measurement results of the surface roughness of the second embodiment.
FIG. 11 is a diagram showing the measurement results of the surface roughness of the second example.
FIG. 12 is a diagram showing the measurement results of the surface roughness of the second example.
FIG. 13 is a diagram showing the measurement results of the surface roughness of the second example.
[Explanation of symbols]
1 Laser projector
2 Irradiation angle adjustment mechanism
3 CCD camera
4 Image processing device
5 Display output device
6 Print output device
7 Phase-only correlation processor
8 Image processing computer
9 DUT
10 Irradiation point
11a Standard granular spotted pattern
11b Change granular spotted pattern
12 Rotating shaft
13 Holding member
14 Support members
15 Stepping motor
16 Fixing device
17 CCD device
18 Night Vision Tube
19 Irradiation angle adjustment mechanism

Claims (20)

A laser projector is tilted at a reference angle from the normal direction of the surface of the object to be measured to irradiate the surface of the object with the laser light, and then the laser light is irradiated to the object to be measured. The laser projector is irradiated with laser light while changing the laser beam irradiation angle from the reference angle by deflecting the laser projector in the tilt direction, and the laser is fixed by an imaging device fixed in a direction facing the surface of the object to be measured. The granular spot pattern, which is reflected light of light, is imaged, and the irradiation angle of the laser beam is changed from the reference angle based on the reference granular spot pattern, which is a granular spot pattern when the laser beam is irradiated from the reference angle. A surface roughness measuring method using laser reflected light for determining a surface roughness of the object to be measured by measuring a change in a changed granular spotted pattern which is a granular spotted pattern. The laser projector is tilted at a reference angle from the normal direction of the surface of the object to be measured to irradiate the surface of the object to be measured with the laser light, and the image pickup device provided in a direction facing the surface of the object to be measured. A granular spot pattern which is reflected light of laser light is imaged, and then the object to be measured is connected in a direction connecting the laser projector and the image pickup device around a point irradiated with the laser light to the object to be measured. Granular spots when the laser beam is irradiated from the reference angle by changing the laser beam irradiation angle from the reference angle by deflecting the laser projector and the imaging device relative to each other. The surface roughness of the object to be measured is measured by measuring a change in the granular spotted pattern, which is a granular spotted pattern when the irradiation angle of the laser beam is changed from the reference angle on the basis of the reference granular spotted pattern that is a pattern. Re Surface roughness measuring method according The reflected light. The surface roughness measurement method using laser reflected light according to claim 1 or 2, wherein the orientation of the imaging device facing the surface of the object to be measured is a substantially normal direction of the surface of the object to be measured. The measurement object is calculated by calculating a change amount of the reference granular spot pattern and the change granular spot pattern at each irradiation angle of the laser beam, and calculating a change rate (change amount / change amount of the irradiation angle) from the change amount. The surface roughness measuring method by laser reflected light according to any one of claims 1 to 3, wherein the surface roughness of the surface is determined. The surface roughness measurement method using laser reflected light according to claim 4, wherein the amount of change between the reference granular spotted pattern and the changed granular spotted pattern is the amount of change in the degree of coincidence between the reference granular spotted pattern and the changed granular spotted pattern. . The change in the degree of coincidence between the reference granular spotted pattern and the changed granular spotted pattern is expressed as a function of the moving distance of the changed granular spotted pattern, and the surface roughness of the object to be measured is obtained from the coefficient of the function. 5. A surface roughness measuring method using laser reflected light according to item 5. The surface roughness measurement method using laser reflected light according to claim 6, wherein the surface roughness of the object to be measured is obtained from a coefficient of a first-order term of the function. The surface roughness of the object to be measured is obtained by measuring in advance the standard change rate of a plurality of standard pieces whose surface roughness is known, and comparing the measured change rate of the measured object with the standard change rate. The surface roughness measuring method by laser reflected light according to claim 4 or 5. The surface roughness measurement method using laser reflected light according to any one of claims 1 to 8, wherein the captured granular spotted pattern is subjected to image processing by a correlation method, and a change in the changed granular spotted pattern with respect to the reference granular spotted pattern is measured. . 10. The surface roughness measurement method using laser reflected light according to claim 9, wherein the correlation method is a phase-only correlation method, and a change in the change granular spot pattern with respect to the reference granular spot pattern is measured from an outline image of the granular spot pattern. . A laser projector provided to irradiate the surface of the object to be measured with a reference angle inclined from the normal direction, and the laser projector to be tilted around the irradiation point of the laser light to the object to be measured. An irradiation angle adjusting mechanism that changes the irradiation angle of the laser beam from the reference angle by deflecting in the direction, and a direction facing the surface of the object to be measured so as to image a granular spot pattern that is a reflected light of the laser beam When the laser beam irradiation angle is changed from the reference angle on the basis of the imaging device fixed to the reference and the reference granular spot pattern which is a granular spot pattern when the laser beam is irradiated from the reference angle An apparatus for measuring surface roughness by laser reflected light, comprising: an image processing apparatus that obtains the surface roughness of the object to be measured by measuring a change in a change granular spot pattern that is a granular spot pattern. A laser projector provided to irradiate the surface of the object to be measured with a reference angle inclined from the normal direction, and a granular spot pattern that is a reflected light of the laser light to image the object to be measured. An imaging device provided in a direction facing the surface, and the laser projector with the measurement object in a direction connecting the laser projector and the imaging device with a laser beam irradiation point on the measurement object An irradiation angle adjustment mechanism that changes the irradiation angle of the laser beam from the reference angle by deflecting the image with respect to the imaging device, and a reference granular spot that is a granular spot pattern when the laser beam is irradiated from the reference angle An image processing apparatus for determining the surface roughness of the object to be measured by measuring a change in a changed granular spot pattern, which is a granular spot pattern when a laser beam irradiation angle is changed from the reference angle with reference to a pattern Tokara Surface roughness measuring device using a laser reflected light. The image processing apparatus calculates a change amount of the reference granular spotted pattern and the changed granular spotted pattern at each irradiation angle of laser light, and calculates a change rate (change amount / change amount of irradiation angle) from the change amount. The surface roughness measuring apparatus by laser reflected light according to claim 11 or 12, wherein the surface roughness of the object to be measured is obtained. The surface roughness measuring device by laser reflected light according to claim 13, wherein the amount of change between the reference granular spotted pattern and the changed granular spotted pattern is the amount of change in the degree of coincidence between the reference granular spotted pattern and the changed granular spotted pattern. . The image processing device represents a change in the degree of coincidence between the reference granular spotted pattern and the changed granular spotted pattern as a function of a moving distance of the changed granular spotted pattern, and calculates a surface roughness of the object to be measured from a coefficient of the function. The surface roughness measuring device by laser reflected light according to claim 14, which is obtained. The surface roughness measurement apparatus using laser reflected light according to claim 15, wherein the image processing apparatus obtains the surface roughness of the object to be measured from a coefficient of a first-order term of the function. The image processing apparatus includes a storage device that stores a standard change rate of a plurality of standard pieces whose surface roughnesses measured in advance are known, and compares and compares the change rate of the measurement object with the standard change rate. The surface roughness measuring device using laser reflected light according to claim 13 or 14, wherein the surface roughness of the object to be measured is obtained. The image processing apparatus has a correlation processing function for performing image processing on the captured granular spotted pattern by a correlation method, and the correlation processing function is used to measure a change in the changed granular spotted pattern with respect to the reference granular spotted pattern. The surface roughness measuring apparatus by the laser reflected light in any one of Claims 11 thru | or 17. 19. The surface roughness due to laser reflected light according to claim 18, wherein the correlation method is a phase-only correlation method, and a change in the change granular spot pattern with respect to the reference granular spot pattern is measured from an outline image of the granular spot pattern. Measuring device. The surface roughness measuring apparatus using laser reflected light according to any one of claims 11 to 19, wherein the imaging device includes a CCD element and a night vision tube provided in front of the CCD element for blocking external light.

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