JP2004138681A

JP2004138681A - Beam emission angle correcting element and laser marking apparatus with the same installed on

Info

Publication number: JP2004138681A
Application number: JP2002301089A
Authority: JP
Inventors: Koji Nishimura; 西村　孝司
Original assignee: Hitachi Koki Co Ltd
Current assignee: Koki Holdings Co Ltd
Priority date: 2002-10-15
Filing date: 2002-10-15
Publication date: 2004-05-13
Anticipated expiration: 2022-10-15
Also published as: JP3991837B2

Abstract

<P>PROBLEM TO BE SOLVED: To provide an angle correcting optical element capable of easily and highly accurately correcting the emission angle of a beam and a laser marking apparatus which is equipped with the same and low-priced and can carry out irradiation with a plurality of line light beams. <P>SOLUTION: The beam emission angle correcting element is formed of a flat plate member of glass, plastic, etc., capable of transmitting light and its beam incidence surface and beam emitting surface form a specified angle. Namely, the incidence surface and emitting surface are so configured to satisfy α=θ/(n-1), where θ is an angular error with respect to the traveling direction of a beam incident on the beam emission angle correcting element, (n) is the refractive index of an optical element for angle correction, and α is the apex angle formed by the incidence surface and emitting surface of the optical element for angle correction. The angular error of the beam can be corrected by transmitting the beam through the optical element for angle correction. Further, the laser marking apparatus is constituted by incorporating the optical element for angle correction in a line light generation optical system and then the laser marking apparatus which has very high indication accuracy can be obtained at a low price. <P>COPYRIGHT: (C)2004,JPO

Description

【０００１】
【発明の属する技術分野】
本発明は、主として１本のレーザ光を複数本のレーザ光に分割するためのビームスプリッター及びそのビームスプリッターを使用したレーザ墨出し装置に関するものである。
【０００２】
【従来の技術】
家屋建築の際、特に工事の開始時には各種部材の取り付け基準位置の設定や部材加工の位置決め等に水準線を出す作業、すなわち墨出し作業が必須である。そこで建築現場では、レベル測量儀等の器具を用いてレベル出しを行い、対象となる構造物の壁に複数のマーク（墨）をつけ、それらをつないで墨出しラインを形成し工事基準としていた。
【０００３】
しかし、この作業は最低でも２人で行う必要があり、非常に手間が掛かり、効率が悪いという問題があった。この問題を改善するために、最近ではライン光照射機能を有するレーザ墨出し装置を用いて効率良く墨出し作業を行うことが多くなった。レーザ墨出し装置は１人で墨出し作業を容易に行うことができるため、建築作業には欠かせない建築作業必須ツールとなりつつある。
【０００４】
墨出しラインには床から壁、天井にかけて垂直線を描くいわゆる『たちライン』や２本の『たちライン』を同時に照射させることで天井に直角ラインを描く『大矩ライン（おおがねライン）』あるいは壁に水平線を描く『ろくライン』あるいはレーザ墨出し装置の直下の床上に集光したレーザビームを照射する『地墨』等いろいろなラインが存在する。
【０００５】
レーザ墨出し装置を用いた墨出し作業の効率化を図るには、１台のレーザ墨出し装置で複数の墨出しラインが照射できることが望まれる。そこで最近では１台の装置で２ライン以上のライン照射が可能な装置が提案されている。
【０００６】
１台のレーザ墨出し装置から複数ラインを照射するためには、複数個のレーザ光源を搭載する方式か、１個のレーザ光源から出射されたレーザ光を分割することにより複数ラインを得る方式が考えられる。
【０００７】
１本のレーザ光を分割することにより複数のライン光を得る方式としては、従来方法はレーザ出射方向に複数のハーフミラーを直列に積層した構造の出射光学系を用いる方式が知られている（特許文献１参照）。
【特許文献１】
特開平９−１５９４５１号（図１及び図３）
【０００８】
【発明が解決しようとする課題】
レーザ墨出し装置から照射されるライン光は理想的な水平線及び理想的な垂直線に近いほど、ライン指示精度は良くなる。したがって、複数個のレーザ光源を用いる従来のレーザ墨出器では、ライン指示精度を出すために個々のレーザ光源付属の光学系について光学調整を行う必要がある。しかしながらこの組立調整にはかなりの手間がかかり、装置のコストも高くなると言う問題がある。
【０００９】
一方、１本のレーザ光を分割することにより複数のライン光を得る方式としては、例えば特開平９−１５９４５１号に開示されるように、レーザ出射方向に複数のハーフミラーを直列に積層した構造の出射光学系を用いる方式が知られている。しかし、この方式の場合、出射光の角度を調節するためにはハーフミラーの設置角度を微調整する必要があり，機構が複雑かつ部品点数が増えてしまう。ちなみに特開平９−１５９４５１号に示された方式では特にハーフミラーの角度調整機構は設けていないため、出射光の指示精度を高めることは困難である。
【００１０】
本発明の目的は、このような従来の課題を解決した簡易なビーム出射角度補正素子及びそれを搭載したレーザ墨出し装置を提供することにある。
【００１１】
【課題を解決するための手段】
上記の目的を達成するために本発明は、ガラス又はプラスチック等の光透過体よりなる平板であって、角度誤差を補正すべき光の入射面と、出射面を有し、上記入射面と出射面とのなす角度αが、上記光透過体の屈折率に依存する所定の値となるように上記入射面と出射面を形成した光学素子によりビーム出射角度を補正するようにしたことに一つの特徴がある。このように構成することにより簡単且つ高精度でビーム角度を補正することが可能になる。また、上記角度補正の効果は、光学素子の配置の精度に依存しないため、該角度補正光学素子を光学系に組み込むときに精度を必要としないという利点がある。
【００１２】
本発明の特徴をさらに具体的に言えば、ビームの進行方向に対する角度誤差をθ、角度補正用光学素子の屈折率をｎ、該角度補正用光学素子の入射面と出射面がなす頂角をαとした時、頂角の大きさがα＝θ／（ｎ−１）又はその近傍となるように上記入射面と出射面を形成したことにある。すなわち、角度補正用の光学素子の頂角を、入射ビームの入射角度と光学素子の屈折率だけから決定できるため光学素子の設計が極めて容易である。
【００１３】
本発明の他の特徴は、角度補正用光学素子の入射面と出射面のなす頂角αを１．１θ≦α≦２．２θの範囲に設定したことにある。このように構成すると、通常のガラスあるいはプラスチックを用いた場合、角度補正用光学素子の頂角を、容易に設計することができる。
【００１４】
本発明の他の特徴は、角度補正用光学素子の屈折率ｎが１．４７≦ｎ≦１．５３の範囲にあってかつ頂角αが２θ、あるいはその近傍に選定したことにある。このようにすると、一般的な角度精度を有する光学素子を用いてライン光を発生した場合、レーザ墨出し器のライン光指示精度を仕様範囲に収めることが可能になる。
【００１５】
本発明の他の特徴は、角度補正用光学素子は、少なくとも２つの平行な面と、所定の角度をなすように形成された第１及び第２の面とを有し、入射光は上記第１の面に照射し、上記第２の面から光線を出射するように配置したことにある。前述のように本発明においては、入射面と出射面の角度は補正に影響するが、そのほかの形状や大きさに影響を受けずに補正することができる。
【００１６】
本発明の他の特徴は、互いに直交する軸をｘ，ｙ，ｚとしたとき、ｚ−ｙ面からｘ方向に光ビームを出射するビーム照射光学系と、第１及び第２のビーム出射角度補正用光学素子から出射角度補正装置を構成し、第１の光学素子はｘ−ｙ面における光ビームの傾きを補正し、第２の光学素子はｘ−ｚ面における光ビームの傾きを補正するように配置したことにある。このように構成すると３次元的な出射角度誤差を互いに直交する２つの正射影成分に分けて書く成分ごとに角度補正を行なうことができる。
【００１７】
本発明の他の特徴は、互いに直交する軸をｘ，ｙ，ｚとしたとき、ｚ−ｙ面からｘ方向に光ビームを出射するビーム照射光学系と、該光ビームの出射角度を補正するための光学素子とより光ビーム出射角度補正装置を構成し、上記光学素子は、ｘ−ｙ面及びｘ−ｚ面の両方における光ビームの傾きを補正するために、ｚ−ｙ面内で適当な角度傾斜して配置したことにある。このように配置すると、１個の補正素子で３次元的角度誤差を補正することが可能になる。
【００１８】
本発明の他の特徴は、上記のような角度補正光学素子および光ビーム出射角度補正装置をライン光発生光学系に組み込んでレーザ墨出し装置を構成したことにある。このように構成することにより、非常に高い指示精度を有するレーザ墨出し装置を低価格で得ることが可能になる。
本発明の他の特徴及び効果は以下の実施形態の説明から更に明確に理解される。
【００１９】
【発明の実施の形態】
（実施形態１）
本発明のビーム出射角度補正素子１の一実施例を図１に示す。本発明にかかるビーム出射角度補正素子１は、ガラス又はプラスチック等の光透過体で構成された平板であり、図１の紙面と垂直方向に厚みを有する。本実施形態ではガラス材であるＢＫ７（屈折率１．５）を用いた。同図において２が光の入射面、３が光の出射面を示し、その入射面２と出射面３は所定の角度αをなすように形成されている。
【００２０】
次に図２を用いて本発明のビーム出射角度補正素子１の原理を説明する。別の光学系（図示しない）から出射したビームＢ１が理想的なビームの進行ライン（ｘ軸）と角度δずれている場合について考える。今、ビーム出射角度補正素子１の入射面２がｘ軸とπ／２−ξの角度だけ傾いて設置されており、さらに入射面２の法線に対してビームＢ１が角度θ_１傾いて入射し、更に、ビーム出射角度補正素子１内部を進むビームＢ２は、上記の法線に対して角度γ傾いて進むとする。ビーム出射角度補正素子１の屈折率をｎとするとスネルの法則により
ｓｉｎθ_１＝ｎ・ｓｉｎγ　　　　（１）
が成り立つ。ここでビーム出射角度補正素子１外部は空気であるため屈折率は１である。
【００２１】
また、ビーム出射角度補正素子１内部を進むビームＢ２は、出射面３の法線に対してα−γの角度をなす。ビーム出射角度補正素子１内部から出射したビームＢ３が出射面３の法線となす角度をθ_２とするとスネルの法則により
ｎ・ｓｉｎ（α−γ）＝ｓｉｎθ_２　　　　（２）
が成り立つ。
（１）式から　　　ｓｉｎγ＝（１／ｎ）・ｓｉｎθ_１　（３）
（３）式を変形して
ｃｏｓγ＝（１／ｎ）・（ｎ^２−ｓｉｎ^２θ_１）^１／２　　（４）　となる。
次に（２）式から
ｓｉｎθ_２＝ｎ・ｓｉｎ（α−γ）
＝ｎ・（ｓｉｎα・ｃｏｓγ−ｃｏｓα・ｓｉｎγ）
＝ｎ・（ｓｉｎα・（１／ｎ）・（ｎ^２−ｓｉｎ^２θ_１）^１／２
−ｃｏｓα・（１／ｎ）・ｓｉｎθ_１）
＝ｓｉｎα・（ｎ^２−ｓｉｎ^２θ_１）^１／２−ｃｏｓα・ｓｉｎθ_１　　（５）
となる。
ここでビームＢ１がｘ軸となす角度δは　δ＝ξ−θ_１　（６）
また、出射ビームＢ３がｘ軸となす角度φは　φ＝α−ξ−θ_２　　　（７）
となる。
【００２２】
今、α、θ_１及びδが十分小さい場合、
ｓｉｎθ_１＝θ_１　　　ｓｉｎθ_２＝θ_２　　　ｓｉｎα＝α　　ｃｏｓα＝１
θ_１ ^２＝０
であるため、（５）式は
θ_２＝α・（ｎ^２−θ_１ ^２）^１／２−θ_１）
＝ｎ・α−θ_１　　（８）
出射ビームＢ３がｘ軸となす角度φは（７）式に（８）式を代入して
φ＝α−ξ−（ｎ・α−θ_１）
＝α−ｎ・α−（ξ−θ_１）
＝α−ｎ・α−δ　　　　　（９）
ここでφが０となるのは（９）式においてφ＝０とすると
α−ｎ・α−δ＝０
上式を変形して
α＝−δ／（ｎ−１）　　　（１０）
となる。すなわちビームＢ１がｘ軸となす角度δに対して１／（ｎ−１）倍の
角度αを有するビーム出射角度補正素子１にビームを透過させることにより、
ビーム出射角度補正素子１からの出射光がｘ軸となす角度は０となるように補正される。また、（１０）式から明らかなようにこの角度補正は、ビーム出射角度補正素子１のｘ軸に対する設置角度には依存しない。
【００２３】
今、ある光学系からの出射ビームがｘ軸と０．０１°の角度をなしている場合、このビームの進行方向をｘ軸の方向と一致させるためには（１０）式からα＝−０．０１／（ｎ−１）の角度を有するビーム出射角度補正素子１を用いて角度補正を行えばよい。ビーム出射角度補正素子１の材質をＢＫ７（屈折率＝１．５）とすると、
α＝−０．０１／（１．５−１）＝−０．０２°となる。
【００２４】
図３に本発明のビーム出射角度補正素子１の実装例を示す。上述の通り角度補正の効果はビーム出射角度補正素子１とｘ軸がなす取り付け角度には依存しないが、取り付けの方向は重要である。本実施例では図３に示すように入射ビームＢ１がｘ軸に対し、＋０．０１°傾いているのでビーム出射角度補正素子１の０．０２°の角度を有する方向は図面下向きに設置する必要がある。すなわち補正素子１の幅の狭い部分がｘ軸の下方に、幅の広い部分がｘ軸の上方に位置するようにこの素子１を配置する。逆に、入射ビームＢ１がｘ軸に対して−０．０１°傾いている場合にはビーム出射角度補正素子１の０．０２°の角度を有する方向は図面上向きに配置する。但し、素子の厚み、外形の大きさには全く無関係であるため、補正が必要な光学系のサイズに応じて角度補正素子を自由に設計することができる。
【００２５】
（実施形態２）
本発明のビーム出射角度補正素子１をレーザ墨出し装置に実装した形態について説明する。図４に示すようにレーザ墨出し装置１０は基本的にはライン光を発生させる光学系１４と光学系を水平に保つための支持機構部１５から構成されている。図５にライン光発生光学系１４の一例の概略を示す。
【００２６】
レーザー墨出し装置本体に対して水平方向に配置した半導体レーザ１６から出射されたレーザビームはコリメータレンズ１７によりビーム断面形状が円形であるコリメート光（平行光）Ｂ１に変換される。本実施形態ではコリメート光Ｂ１のビーム径は２ｍｍになるように設定している。また、光学系１４はビームスプリッター４が用いられており入射光を３本の均一な強度の光に分岐している。すなわちこのビームスプリッター４はこの実施例ではガラス又はプラスチック等の光を透過する３個の部材を貼り合わせて構成され直方体形状をしている。第１の部材と第２の部材の貼り合わせ面には第１の光分離面４１が形成されている。すなわちこの光分離面４１で入射光が透過光と反射光に分離される。
【００２７】
さらに第２の部材と第３の部材の貼り合わせ面には第２の光分離面４２が形成されている。上記の反射光はビームスプリッター４の内部を進み、第２の光分離面で更に反射光と透過光に分離されるので３本の分岐光を得ることができる。したがって各光線の光路上にロッドレンズ５１、５２、５３を配置することで３本のライン光を得ることができる。
【００２８】
ここでビームスプリッター４は必ず加工誤差を持っているため、分岐光の出射角度には若干の誤差が含まれる。しかしレーザ墨出し装置の場合、ライン光の指示精度が厳しく規定されており、例えばライン光を照射し１０ｍ先で１ｍｍ以内の指示精度に押さえる必要がある。１０ｍで１ｍｍの精度に押さえるには、ビームスプリッター４の出射光が、理想的な水平線（ｘ軸）となす角度を０．００５°以内としなければならない。つまり各分岐光が理想ラインとなす角度が０．００５°を超える場合、補正が必要となる。この実施例ではビームスプリッター４から出射した光線の各光路にビーム出射角度補正素子１ａ、１ｂ、１ｃが配置されている。例えば各分岐光が理想ラインとなす角度が０．０３°である場合、α＝−０．０３／（１．５−１）＝０．０６°の角度を有するビーム出射角度補正素子１を用いて角度補正を行うことにより、補正素子からの出射光が理想ラインとなす角度は０となる。角度補正素子１ａ、１ｂ、１ｃの後にロッドレンズ５１、５２、５３を配置することにより発生するライン光の指示精度は０となり、理想ラインと一致する。
【００２９】
次に角度補正素子１ａ、１ｂ、１ｃにおいてα＝−２δである時、各角度補正素子１ａ、１ｂ、１ｃが補正効果を発揮するための屈折率の範囲を規定する。図３に示すように角度補正素子１の入射面がｘ軸に直交するように配置されている場合について考える。これは図２においてξ＝０の場合に相当する。したがって、（７）式から
φ＝α−ξ−θ_２
＝α−θ_２　　　　　（１１）
ここでθ_２は（８）式からθ_２＝ｎ・α−θ_１　であるため、これを（１１）式に
代入してまとめると　　φ＝（１−ｎ）α＋θ_１　　　（１２）　となる。
【００３０】
ここで上述の通り、角度補正素子１の頂角はα＝−２δであり、さらに（６）式からδ＝ξ−θ_１　であるが、ξ＝０のため　δ＝−θ_１となる。したがってα＝２θ_１　である。これを（１２）式に代入してまとめると
φ＝（１−ｎ）（２θ_１）＋θ_１
＝（３−２ｎ）θ_１　　　（１３）　　となる。（１３）式を変形して
ｎ＝（３−φ／θ_１）／２　　（１４）　が得られる。
【００３１】
ここでレーザ墨出し器において一般的な光学素子の角度精度は３分程度であるので、この精度３分で作製した光学素子を用いてライン光を発生させた場合，生じ得るライン光指示精度の最大値は±０．０８°程度となる。一方、本実施例で検討しているレーザ墨出し器のライン光指示精度の許容値は０．００５°であるため、（１４）式においてθ_１＝±０．０８　，φ＝０．００５　を代入し、ｎを計算すると
それぞれ　ｎ＝１．４６８８　，　ｎ＝１．５３１３　が得られる。
すなわち、角度補正素子１の屈折率ｎが
１．４６８８≦ｎ≦１．５３１３の範囲にあれば、レーザ墨出し器のライン光指示精度が仕様範囲に収まることが分かる。
すなわち、角度補正素子１の屈折率は概略　１．４７≦ｎ≦１．５３　であればよい。また、一般的にガラスあるいはプラスチック材の屈折率は
１．４５≦ｎ≦１．９０　の範囲に存在しているため、（１０）式に
上記のｎの値を代入し計算するとそれぞれ　α＝−１．１δ　α＝−２．２δとなる。ξ＝０の時、δ＝−θ_１　であるため
α＝１．１θ_１　　α＝２．２θ_１　　となる。
【００３２】
（実施形態３）
次に図６に示すようにビーム照射光学系６０からの出射ビームＢ１がｘ軸に対して３次元的に傾いている場合の角度補正に関する実施形態について説明する。図６に示すようにｘ、ｙ、ｚ座標を定め、ｘｙ平面及びｘｚ平面に対するビームＢ１の正射影を考える。ｘｙ平面の正射影を図７に示し、ｘｚ平面に対する正射影を図８に示す。
【００３３】
例えばｘｙ平面への正射影Ｂ１ｘｙがｘ軸となす角度をδｘｙとすると、式（１０）から角度補正素子１ｘｙの頂角の大きさδは−δｘｙ／（ｎ−１）となる。ここで角度補正素子１ｘｙの材質をＢＫ７（屈折率１．５）とすると、α＝−２δｘｙとなる。負号を考慮すると角度補正素子１ｘｙにより角度補正がなされ出射ビームＢ３ｘｙのようにｘ軸に平行な光に変換される。
【００３４】
これはｘｚ平面への正射影Ｂ１ｘｚに対しても全く同様である。この場合はα＝−２δｘｚの頂角を有する角度補正素子１ｘｚを図８のように配置することでｘ軸に平行なビームＢ３ｘｚを得ることができる。すなわち、ｘ軸に対して３次元的に傾いているビームの角度補正方法としては図１０に示すように角度補正素子１ｘｙ及び１ｘｚを互いに直交するように配置し各正射影毎に角度補正を行う。
【００３５】
（実施形態４）
次に本発明による角度誤差補正の別の実施形態について説明する。
今、図６においてビームＢ１がｘ軸となす角度をδとすると、頂角の大きさが−δ／（ｎ−１）である角度補正素子１を用いることでｘ軸に平行なビームを得ることができる。ただし、この場合ビームＢ１はｘｙ平面あるいはｘｚ平面上に無いため、角度補正素子１をｙ軸あるいはｚ軸に平行に配置することでは補正を十分に行うことはできない。ｙ軸に対して所定の角度をなすように角度補正素子１を配置することが必要となる。ｙ軸に対する角度補正素子１の配置角度は次のようになる。ビームＢ１のｙｚ平面に対する正射影を考えるとそれは図９のようになる。
【００３６】
正射影Ｂ１ｙｚがｙ軸となす角度をδｙｚとした時、このδｙｚが角度補正素子１の配置角度となる。今、角度補正素子１の材質をＢＫ７（屈折率１．５）とすると、図１１に示すように頂角α＝−２δである角度補正素子１をｙ軸に対してδｙｚとなるように配置することによりｘ軸と完全に平行となる出射ビームを得ることが可能となる。実際には上述の角度補正素子１をｘ軸を回転軸として適当に回転させ出射ビームＢ３とｘ軸のなす角度が０になる位置で角度補正素子１を固定すればよい。
【００３７】
【発明の効果】
上述のように本発明によるビーム出射角度補正素子を用いれば、簡易な方法で，ビーム出射角度を補正することが可能となる。また、本発明によるビーム出射角度補正素子をレーザ墨出し装置の光学系に搭載することで非常に高い指示精度のライン光を容易に得ることができるため、低コストで複数本の高精度墨出し用レーザライン光を発生させることが可能となった。その結果、従来は非常に高価であった複数ライン光照射用レーザ墨出し装置を低価格で得ることが可能となった。
【図面の簡単な説明】
【図１】本発明のビーム出射角度補正素子の一実施例を示す概略図。
【図２】本発明のビーム出射角度補正素子による角度補正原理を示す図。
【図３】本発明のビーム出射角度補正素子の一実施例を示す概略図。
【図４】本発明のビーム出射角度補正素子を搭載したレーザ墨出し装置の概略図。
【図５】本発明のレーザ墨出し装置におけるライン光発生光学系の概略図。
【図６】光学系からの出射ビームの様子を示す概略図。
【図７】出射ビームが三次元的に傾いている場合の出射角度補正の原理を説明するための説明図。
【図８】出射ビームが三次元的に傾いている場合の出射角度補正の原理を説明するための説明図。
【図９】出射ビームが三次元的に傾いている場合の出射角度補正の原理を説明するための説明図。
【図１０】本発明のビーム出射角度補正素子の配置についての一実施形態を示す概略図。
【図１１】本発明のビーム出射角度補正素子の配置についての一実施形態を示す概略図。
【符号の説明】
１、１ａ、１ｂ、１ｃ：ビーム出射角度補正素子
２：入射面
３：出射面
４：ビームスプリッタ−
１０：レーザ墨出し装置
１４：ライン光発生光学系
１５：支持系
１６：半導体レーザ
１７：コリメートレンズ
５１、５２、５３：ロッドレンズ
６０：ビーム照射光学系[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a beam splitter for splitting one laser beam into a plurality of laser beams, and a laser marking device using the beam splitter.
[0002]
[Prior art]
When building a house, especially at the start of construction, it is essential to perform a task of setting a reference position for mounting various members and setting a level line for the positioning of member processing, that is, a blackout operation. Therefore, at the construction site, leveling was performed using instruments such as a level surveyor, multiple marks (black) were attached to the walls of the target structure, and they were connected to form a blacking line, which was used as a construction standard. .
[0003]
However, this operation must be performed by at least two people, which is very time-consuming and inefficient. In order to solve this problem, recently, the ink marking operation has been often performed efficiently using a laser marking device having a line light irradiation function. Since a laser marking device can easily perform a marking operation by one person, the laser marking device is becoming an indispensable building work tool for building work.
[0004]
The so-called "Tachi-Line" which draws a vertical line from the floor to the wall and the ceiling and two "Tachi-Lines" are simultaneously illuminated to draw a right angle line on the ceiling. There are various lines, such as a "Roku line" that draws a horizontal line on a wall, and a "ground ink" that irradiates a focused laser beam on the floor directly below a laser marking device.
[0005]
In order to improve the efficiency of the blackout operation using a laser blackout device, it is desired that a single laser blackout device can irradiate a plurality of blackout lines. Therefore, recently, a device capable of irradiating two or more lines with one device has been proposed.
[0006]
In order to irradiate a plurality of lines from one laser marking device, a method of mounting a plurality of laser light sources or a method of obtaining a plurality of lines by dividing laser light emitted from one laser light source is used. Conceivable.
[0007]
As a method of obtaining a plurality of line lights by dividing one laser light, a method using an emission optical system having a structure in which a plurality of half mirrors are stacked in series in a laser emission direction is known in the related art ( Patent Document 1).
[Patent Document 1]
JP-A-9-159451 (FIGS. 1 and 3)
[0008]
[Problems to be solved by the invention]
The closer the line light emitted from the laser marking device is to the ideal horizontal line and the ideal vertical line, the better the line pointing accuracy. Therefore, in a conventional laser marking device using a plurality of laser light sources, it is necessary to perform optical adjustment on an optical system attached to each laser light source in order to obtain line pointing accuracy. However, there is a problem that this assembling adjustment takes a considerable amount of time and increases the cost of the apparatus.
[0009]
On the other hand, as a method of obtaining a plurality of line lights by dividing one laser light, for example, as disclosed in Japanese Patent Application Laid-Open No. 9-159451, a structure in which a plurality of half mirrors are stacked in series in a laser emission direction is disclosed. Are known. However, in the case of this method, it is necessary to finely adjust the installation angle of the half mirror in order to adjust the angle of the emitted light, so that the mechanism is complicated and the number of parts increases. Incidentally, in the method disclosed in Japanese Patent Application Laid-Open No. 9-159451, it is difficult to increase the pointing accuracy of the emitted light because no angle adjustment mechanism for the half mirror is provided.
[0010]
An object of the present invention is to provide a simple beam emission angle correction element that solves such a conventional problem and a laser marking device equipped with the same.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is directed to a flat plate made of a light transmitting body such as glass or plastic, which has an incident surface for light whose angle error is to be corrected, and an exit surface. The angle α between the light transmitting surface and the light emitting angle is corrected by an optical element having the light incident surface and the light emitting surface so as to have a predetermined value depending on the refractive index of the light transmitting body. There are features. With this configuration, it is possible to easily and accurately correct the beam angle. Further, since the effect of the angle correction does not depend on the accuracy of the arrangement of the optical element, there is an advantage that no accuracy is required when the angle correction optical element is incorporated into an optical system.
[0012]
More specifically, the characteristics of the present invention are as follows: the angle error with respect to the traveling direction of the beam is θ, the refractive index of the angle correction optical element is n, and the apex angle between the entrance surface and the output surface of the angle correction optical element is n. When α is set, the incident surface and the outgoing surface are formed such that the magnitude of the apex angle is α = θ / (n−1) or in the vicinity thereof. That is, since the vertex angle of the optical element for angle correction can be determined only from the incident angle of the incident beam and the refractive index of the optical element, the design of the optical element is extremely easy.
[0013]
Another feature of the present invention resides in that the apex angle α between the entrance surface and the exit surface of the angle correcting optical element is set in a range of 1.1θ ≦ α ≦ 2.2θ. With this configuration, when ordinary glass or plastic is used, the apex angle of the angle correcting optical element can be easily designed.
[0014]
Another feature of the present invention is that the refractive index n of the angle correcting optical element is in the range of 1.47 ≦ n ≦ 1.53 and the apex angle α is selected to be 2θ or in the vicinity thereof. In this way, when line light is generated using an optical element having general angular accuracy, it is possible to keep the line light indicating accuracy of the laser marking device within the specification range.
[0015]
Another feature of the present invention is that the angle correcting optical element has at least two parallel surfaces and first and second surfaces formed so as to form a predetermined angle, and the incident light is reflected by the first and second surfaces. It is arranged so that light is emitted to the first surface and light rays are emitted from the second surface. As described above, in the present invention, the angle between the entrance surface and the exit surface affects the correction, but the correction can be performed without being affected by other shapes and sizes.
[0016]
Another feature of the present invention is that, when axes orthogonal to each other are x, y, and z, a beam irradiation optical system that emits a light beam in the x direction from the xy plane, and first and second beam emission angles The correction optical element constitutes an emission angle correction device, wherein the first optical element corrects the tilt of the light beam on the xy plane, and the second optical element corrects the tilt of the light beam on the xz plane. It is arranged in such a way. With this configuration, it is possible to perform the angle correction for each component to be written by dividing the three-dimensional emission angle error into two orthogonal projection components orthogonal to each other.
[0017]
Another feature of the present invention is that, when axes orthogonal to each other are x, y, and z, a beam irradiation optical system that emits a light beam in the x direction from the zy plane and an emission angle of the light beam are corrected. And an optical element for correcting the inclination of the light beam in both the xy plane and the xz plane. It is that it was arranged at an inclined angle. With this arrangement, it is possible to correct a three-dimensional angle error with one correction element.
[0018]
Another feature of the present invention resides in that a laser marking device is configured by incorporating the above-described angle correction optical element and the light beam emission angle correction device into a line light generation optical system. With this configuration, it is possible to obtain a laser marking device having extremely high pointing accuracy at a low price.
Other features and advantages of the present invention will be more clearly understood from the following description of the embodiments.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
(Embodiment 1)
FIG. 1 shows an embodiment of a beam emission angle correction element 1 according to the present invention. The beam emission angle correction element 1 according to the present invention is a flat plate made of a light transmitting body such as glass or plastic, and has a thickness in a direction perpendicular to the plane of FIG. In this embodiment, BK7 (refractive index: 1.5) which is a glass material is used. 2, reference numeral 2 denotes a light incident surface, and 3 denotes a light emitting surface. The incident surface 2 and the emitting surface 3 are formed so as to form a predetermined angle α.
[0020]
Next, the principle of the beam emission angle correction element 1 of the present invention will be described with reference to FIG. Consider a case where the beam B1 emitted from another optical system (not shown) is shifted from the ideal beam traveling line (x-axis) by an angle δ. Now, the entrance surface 2 of the beam exit angle correction element 1 is installed at an angle of π / 2-ξ with respect to the x-axis, and the beam B1 is incident at an angle θ _{1 with} respect to the normal of the entrance surface 2. Further, it is assumed that the beam B2 traveling inside the beam emission angle correction element 1 advances at an angle γ with respect to the normal. Assuming that the refractive index of the beam emission angle correction element 1 is n, sin θ ₁ = n · sin γ (1) according to Snell's law.
Holds. Here, since the outside of the beam emission angle correction element 1 is air, the refractive index is 1.
[0021]
Further, the beam B2 traveling inside the beam emission angle correction element 1 forms an angle of α-γ with respect to the normal of the emission surface 3. Beam emission angle when the correction element 1 beam B3 emitted from the inside to the angle between the normal line of the exit surface 3 and theta ₂ according to Snell's law n · sin (α-γ) = sinθ 2 (2)
Holds.
From equation (1), sinγ = (1 / n) · sinθ ₁ (3)
By modifying the equation (3), cosγ = (1 / n) · (n ² −sin ² θ ₁ ) ^1/2 (4).
Next, from equation (2), sin θ ₂ = n · sin (α−γ)
= N · (sinα · cosγ-cosα · sinγ)
= N · (sin α · (1 / n) · (n ² −sin ² θ ₁ ) ^1/2
−cos α · (1 / n) · sin θ ₁ )
= Sin α · (n ² −sin ² θ ₁ ) ^1/2 −cos α · sin θ ₁ (5)
It becomes.
Here, the angle δ that the beam B1 makes with the x axis is δ = ξ−θ ₁ (6)
The angle φ formed by the output beam B3 and the x-axis is φ = α−ξ−θ ₂ (7)
It becomes.
[0022]
Now, if α, θ ₁ and δ are small enough,
sin θ ₁ = θ ₁ sin θ ₂ = θ ₂ sin α = α cos α = 1
θ ₁ ² = 0
Because it is, equation (5) _{^{θ 2 = α · (n 2}} -θ 1 2) 1/2 -θ 1)
= N · α-θ ₁ (8)
The angle φ formed by the outgoing beam B3 with the x-axis is obtained by substituting equation (8) into equation (7), and φ = α−ξ− (n · α−θ ₁ )
= Α-n · α- (ξ-θ ₁ )
= Α-n · α-δ (9)
Here, φ becomes 0 when α = 0 in equation (9), α−n · α−δ = 0.
The above equation is transformed into α = −δ / (n−1) (10)
It becomes. That is, by transmitting the beam to the beam emission angle correction element 1 having an angle α that is 1 / (n−1) times the angle δ that the beam B1 forms with the x axis,
The angle formed by the light emitted from the beam emission angle correction element 1 and the x axis is corrected to be zero. Further, as is apparent from the equation (10), this angle correction does not depend on the installation angle of the beam emission angle correction element 1 with respect to the x-axis.
[0023]
Now, if the beam emitted from an optical system forms an angle of 0.01 ° with the x axis, in order to make the traveling direction of this beam coincide with the direction of the x axis, α = −0 from equation (10). Angle correction may be performed using the beam emission angle correction element 1 having an angle of .01 / (n-1). If the material of the beam emission angle correction element 1 is BK7 (refractive index = 1.5),
α = −0.01 / (1.5−1) = − 0.02 °
[0024]
FIG. 3 shows a mounting example of the beam emission angle correction element 1 of the present invention. As described above, the effect of the angle correction does not depend on the mounting angle between the beam output angle correcting element 1 and the x-axis, but the mounting direction is important. In this embodiment, as shown in FIG. 3, since the incident beam B1 is inclined by + 0.01 ° with respect to the x-axis, the direction of the beam output angle correction element 1 having an angle of 0.02 ° needs to be set downward in the drawing. There is. That is, the correction element 1 is arranged such that the narrow part is located below the x-axis and the wide part is located above the x-axis. Conversely, when the incident beam B1 is inclined at −0.01 ° with respect to the x-axis, the direction of the beam emission angle correction element 1 having an angle of 0.02 ° is arranged upward in the drawing. However, since it is completely independent of the thickness of the element and the size of the outer shape, the angle correction element can be freely designed according to the size of the optical system that needs to be corrected.
[0025]
(Embodiment 2)
An embodiment in which the beam emission angle correction element 1 of the present invention is mounted on a laser marking device will be described. As shown in FIG. 4, the laser marking device 10 basically includes an optical system 14 for generating line light and a support mechanism 15 for keeping the optical system horizontal. FIG. 5 schematically shows an example of the line light generating optical system 14.
[0026]
A laser beam emitted from a semiconductor laser 16 arranged in a horizontal direction with respect to the laser marking device main body is converted by a collimator lens 17 into collimated light (parallel light) B1 having a circular beam cross-sectional shape. In the present embodiment, the beam diameter of the collimated light B1 is set to be 2 mm. The beam splitter 4 is used as the optical system 14, and the incident light is split into three light beams having uniform intensity. That is, in this embodiment, the beam splitter 4 is formed by bonding three members such as glass or plastic which transmit light, and has a rectangular parallelepiped shape. A first light separation surface 41 is formed on a bonding surface of the first member and the second member. That is, the incident light is separated by the light separation surface 41 into transmitted light and reflected light.
[0027]
Further, a second light separation surface 42 is formed on a bonding surface of the second member and the third member. The reflected light travels inside the beam splitter 4 and is further separated into reflected light and transmitted light by the second light separation surface, so that three branched lights can be obtained. Therefore, three line lights can be obtained by arranging the rod lenses 51, 52, 53 on the optical path of each light beam.
[0028]
Here, since the beam splitter 4 always has a processing error, the exit angle of the split light includes a slight error. However, in the case of a laser marking device, the pointing accuracy of the line light is strictly specified. For example, it is necessary to irradiate the line light and to keep the pointing accuracy within 1 mm within 10 m. In order to keep the accuracy of 1 mm at 10 m, the angle between the light emitted from the beam splitter 4 and the ideal horizontal line (x-axis) must be within 0.005 °. In other words, when the angle formed by each split light with the ideal line exceeds 0.005 °, correction is necessary. In this embodiment, beam emission angle correction elements 1a, 1b, and 1c are arranged on each optical path of the light beam emitted from the beam splitter 4. For example, when the angle between each of the branched lights and the ideal line is 0.03 °, the beam emission angle correction element 1 having an angle of α = −0.03 / (1.5-1) = 0.06 ° is used. By performing the angle correction, the angle formed by the light emitted from the correction element and the ideal line becomes zero. The pointing accuracy of the line light generated by arranging the rod lenses 51, 52, 53 after the angle correction elements 1a, 1b, 1c becomes 0, which coincides with the ideal line.
[0029]
Next, when α = −2δ in the angle correction elements 1a, 1b, and 1c, the range of the refractive index for each of the angle correction elements 1a, 1b, and 1c to exhibit a correction effect is defined. Consider a case where the incident surface of the angle correction element 1 is arranged so as to be orthogonal to the x-axis as shown in FIG. This corresponds to the case where ξ = 0 in FIG. Therefore, from equation (7), φ = α−ξ−θ ₂
= Α-θ ₂ (11)
Here, since θ ₂ is θ ₂ = n · α−θ ₁ from the expression (8), when it is substituted into the expression (11) and summarized, φ = (1−n) α + θ ₁ (12)
[0030]
Here as described above, the apex angle of the angle correction device 1 is α = -2δ, further (6) it is a δ = ξ-θ ₁ from the equation, a [delta] = - [theta] ₁ for xi] = 0. It is therefore α = 2θ _1. Substituting this into equation (12) and summarizing the result, φ = (1−n) (2θ ₁ ) + θ ₁
= (3-2n) θ ₁ (13) By modifying the expression (13), n = (3-φ / θ ₁ ) / 2 (14) is obtained.
[0031]
Here, since the angle accuracy of a general optical element in a laser marking device is about three minutes, if line light is generated using an optical element manufactured with this accuracy of three minutes, the line light pointing accuracy that can occur may be reduced. The maximum value is about ± 0.08 °. On the other hand, since the allowable value of the line light indicating accuracy of the laser marking device studied in this embodiment is 0.005 °, θ ₁ = ± 0.08 and φ = 0.005 in Expression (14). Substituting and calculating n gives n = 1.4688 and n = 1.51313, respectively.
That is, when the refractive index n of the angle correction element 1 is in the range of 1.4688 ≦ n ≦ 1.5313, it can be seen that the line light pointing accuracy of the laser marking device falls within the specification range.
That is, the refractive index of the angle correction element 1 may be approximately 1.47 ≦ n ≦ 1.53. Further, since the refractive index of glass or plastic material generally exists in the range of 1.45 ≦ n ≦ 1.90, when the above value of n is substituted into the equation (10) and calculated, α = − 1.1δ α = −2.2δ. When ξ = 0, δ = because it is - [theta] ₁ alpha = a 1.1θ _{₁ α} = 2.2θ _1.
[0032]
(Embodiment 3)
Next, a description will be given of an embodiment relating to angle correction when the output beam B1 from the beam irradiation optical system 60 is three-dimensionally inclined with respect to the x-axis as shown in FIG. As shown in FIG. 6, x, y, and z coordinates are determined, and the orthogonal projection of the beam B1 onto the xy plane and the xz plane is considered. FIG. 7 shows an orthographic projection on the xy plane, and FIG. 8 shows an orthographic projection on the xz plane.
[0033]
For example, assuming that the angle formed by the orthogonal projection B1xy on the xy plane and the x-axis is δxy, the magnitude δ of the apex angle of the angle correction element 1xy is −δxy / (n−1) from Expression (10). Here, if the material of the angle correction element 1xy is BK7 (refractive index 1.5), α = −2δxy. In consideration of the negative sign, the angle is corrected by the angle correction element 1xy, and the light is converted into light parallel to the x-axis like the output beam B3xy.
[0034]
This is exactly the same for the orthogonal projection B1xz on the xz plane. In this case, a beam B3xz parallel to the x-axis can be obtained by arranging the angle correction element 1xz having an apex angle of α = −2δxz as shown in FIG. That is, as a method of correcting the angle of a beam three-dimensionally inclined with respect to the x-axis, as shown in FIG. 10, the angle correction elements 1xy and 1xz are arranged so as to be orthogonal to each other, and the angle is corrected for each orthographic projection. .
[0035]
(Embodiment 4)
Next, another embodiment of the angle error correction according to the present invention will be described.
Now, assuming that the angle between the beam B1 and the x-axis in FIG. 6 is δ, a beam parallel to the x-axis is obtained by using the angle correction element 1 whose apex angle is −δ / (n−1). be able to. However, in this case, since the beam B1 is not on the xy plane or the xz plane, it is not possible to sufficiently perform the correction by arranging the angle correction element 1 in parallel with the y axis or the z axis. It is necessary to arrange the angle correction element 1 so as to form a predetermined angle with respect to the y-axis. The arrangement angle of the angle correction element 1 with respect to the y axis is as follows. Considering the orthogonal projection of the beam B1 on the yz plane, it is as shown in FIG.
[0036]
When the angle formed by the orthogonal projection B1yz and the y axis is δyz, δyz is the arrangement angle of the angle correction element 1. Now, assuming that the material of the angle correction element 1 is BK7 (refractive index 1.5), as shown in FIG. 11, the angle correction element 1 having the apex angle α = −2δ is arranged so as to be δyz with respect to the y axis. By doing so, it becomes possible to obtain an output beam completely parallel to the x-axis. In practice, the angle correction element 1 described above may be appropriately rotated around the x axis as a rotation axis, and the angle correction element 1 may be fixed at a position where the angle between the output beam B3 and the x axis becomes zero.
[0037]
【The invention's effect】
As described above, by using the beam emission angle correction element according to the present invention, the beam emission angle can be corrected by a simple method. In addition, by mounting the beam emission angle correction element according to the present invention on the optical system of the laser marking device, it is possible to easily obtain a line light with very high pointing accuracy. It is possible to generate laser line light for use. As a result, it has become possible to obtain a laser marking device for irradiating a plurality of lines at a low cost, which was conventionally very expensive.
[Brief description of the drawings]
FIG. 1 is a schematic view showing one embodiment of a beam emission angle correction element of the present invention.
FIG. 2 is a diagram showing the principle of angle correction by the beam emission angle correction element of the present invention.
FIG. 3 is a schematic diagram showing one embodiment of a beam emission angle correction element of the present invention.
FIG. 4 is a schematic view of a laser marking device equipped with the beam emission angle correction element of the present invention.
FIG. 5 is a schematic diagram of a line light generating optical system in the laser marking device of the present invention.
FIG. 6 is a schematic diagram showing a state of a beam emitted from an optical system.
FIG. 7 is an explanatory diagram for explaining the principle of emission angle correction when the emission beam is three-dimensionally inclined.
FIG. 8 is an explanatory diagram for explaining the principle of emission angle correction when the emission beam is three-dimensionally inclined.
FIG. 9 is an explanatory diagram for explaining the principle of emission angle correction when the emission beam is three-dimensionally inclined.
FIG. 10 is a schematic diagram showing an embodiment of an arrangement of a beam emission angle correction element of the present invention.
FIG. 11 is a schematic view showing an embodiment of an arrangement of a beam emission angle correction element of the present invention.
[Explanation of symbols]
1, 1a, 1b, 1c: beam emission angle correction element 2: incidence surface 3: emission surface 4: beam splitter
10: Laser marking device 14: Line light generating optical system 15: Supporting system 16: Semiconductor laser 17: Collimating lenses 51, 52, 53: Rod lens 60: Beam irradiation optical system

Claims

A light transmitting body such as glass or plastic, which has an incident surface of light whose angle error is to be corrected, and an emitting surface, and an angle α between the incident surface and the emitting surface is a refractive index of the light transmitting body. An optical element for correcting a beam exit angle, wherein the entrance surface and the exit surface are formed so as to have predetermined values depending on the following.

A light transmitting body such as glass or plastic, which has an incident surface for light whose angle error is to be corrected, and an exit surface, and a beam exit angle correction in which the incident surface and the exit surface form a predetermined angle. When the angle error with respect to the traveling direction of the beam is θ, the refractive index of the angle correction optical element is n, and the apex angle between the entrance surface and the exit surface of the angle correction optical element is α, An optical element for correcting a beam emission angle, wherein the incident surface and the emission surface are formed such that the magnitude of the apex angle is α = θ / (n−1) or in the vicinity thereof.

3. An optical element for correcting a beam emission angle according to claim 2, wherein the apex angle α between the incident surface and the emission surface satisfies 1.1θ ≦ α ≦ 2.2θ.

3. The beam emitting angle correcting optical element according to claim 2, wherein the refractive index n of the angle correcting optical element is in a range of 1.47 ≦ n ≦ 1.53, and the apex angle α is 2θ.

In claim 2, the optical element for angle correction has at least two parallel surfaces and first and second surfaces formed so as to form a predetermined angle, and incident light is incident on the first surface. An angle-correcting optical system, which is provided so as to irradiate and emit light rays from the second surface.

A light source composed of a semiconductor laser, an optical element for converting light emitted from the light source into collimated light, a beam emission angle correcting optical element for finely adjusting the emission angle of the collimated light, and a collimated light having an emission angle corrected An optical system for generating line light is provided, and the beam emission angle correcting optical element is a flat plate made of a light transmitting body such as glass or plastic, and has a light incident surface to be corrected for an angular error, and a light emitting surface. Wherein the incident surface and the outgoing surface are formed such that an angle α between the incident surface and the outgoing surface has a predetermined value depending on the refractive index of the light transmitting body. apparatus.

A light source made of a semiconductor laser, a collimating optical element for converting light emitted from the light source into collimated light, a beam emission angle correcting optical element for finely adjusting the emission angle of the collimated light, and a collimated light having an emitted angle corrected The beam emission angle correcting optical element is a flat plate made of a light transmitting body such as glass or plastic, and has a light incident surface to be corrected for an angular error, and a light emitting surface. Having a predetermined angle between the entrance surface and the exit surface, an angle error with respect to the traveling direction of the beam is θ, a refractive index of the angle correction optical element is n, and the angle correction optical element is When the apex angle between the incident surface and the outgoing surface is α, the incident surface and the outgoing surface are formed such that the magnitude of the apex angle is α = θ / (n−1) or in the vicinity thereof. Laser ink featured And equipment.

A light source composed of a semiconductor laser, a collimating optical element that converts light emitted from the light source into collimated light, a beam splitter that generates a plurality of light beams from light beams from the light source, and a plurality of collimated light beams branched from the beam splitter A beam emission angle correcting optical element for fine-tuning the emission angle of the light, and an optical system for generating line light from the collimated light whose emission angle has been corrected, wherein the beam emission angle correction optical element is made of glass, plastic, or the like. A flat plate made of a light transmitting body, having an incident surface of light to be corrected for an angular error, and an outgoing surface, wherein the incident surface and the outgoing surface have a predetermined angle depending on the refractive index of the light transmitting body. A laser marking device characterized in that it is configured to perform.

A light source composed of a semiconductor laser, a collimating optical element that converts light emitted from the light source into collimated light, a beam splitter that generates a plurality of light beams from light beams from the light source, and a plurality of collimated light beams branched from the beam splitter A beam emission angle correcting optical element for fine-tuning the emission angle of the light, and an optical system for generating line light from the collimated light whose emission angle has been corrected, wherein the beam emission angle correction optical element is made of glass, plastic, or the like. A flat plate made of a light transmitting body, having an incident surface of light whose angular error is to be corrected, and an emitting surface, wherein the incident surface and the emitting surface are formed at a predetermined angle, and a traveling direction of the beam; Θ, the refractive index of the angle correcting optical element is n, and the apex angle between the entrance surface and the outgoing surface of the angle correcting optical element is α, the magnitude of the apex angle is A laser marking device characterized in that the incident surface and the outgoing surface are formed so that α = θ / (n−1) or its vicinity.

Assuming that axes orthogonal to each other are x, y, and z, a beam irradiation optical system that emits a light beam in the x direction from the xy plane, and an emission angle including first and second beam emission angle correcting optical elements. A correction device, wherein the first and second optical elements have an incident surface and an exit surface of light whose angle is to be corrected, and have a refractive index of n or a light transmitting body such as glass or plastic. Wherein the first optical element is arranged to correct the inclination of the light beam in the xy plane, and the second optical element is arranged to correct the inclination of the light beam in the xy plane. Angle correction device.

In claim 10, when an angle formed with the x axis when the light beam is orthogonally projected on the xy plane is δxy, an angle α formed between the incident surface and the outgoing surface of the first optical element is δxy / (n -1) A light beam emission angle correction device characterized in that the value is set to or near the value.

In claim 10, when an angle formed with the x-axis when the light beam is orthogonally projected on the xz plane is δxz, an angle α formed between the entrance surface and the exit surface of the second optical element is δxz / (n -1) A light beam emission angle correction device characterized in that the value is set to or near the value.

Assuming that axes perpendicular to each other are x, y, and z, a beam irradiation optical system that emits a light beam in the x direction from the xy plane and an optical element that corrects the emission angle of the light beam A beam emission angle correction device, wherein the optical element has an incident surface and an emission surface for light whose angle is to be corrected, and is made of a light transmitting body such as glass or plastic having a refractive index of n; A light beam emission angle correction device characterized in that the light beam emission angle correction device is disposed at an appropriate angle in the zy plane in order to correct the inclination of the light beam in both the plane and the xz plane.

14. An image forming apparatus according to claim 13, wherein when an angle between the light beam and the x-axis is δ, an angle α between the incident surface and the exit surface of the optical element is δ / (n−1) or in the vicinity thereof. Light beam emission angle correction device.

A laser marking device comprising the light beam emission angle correction device according to claim 10.