![](data:image/png;base64,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光学設計ノーツ 32(ver.1.0)
部分的コヒーレント結像の考え方 2
準単色光
前回から引き続き部分的なコヒーレンシーの扱いについて考える。
光学設計においては点光源から発した、純粋に単一波長の光波(光波が途切れず常に一定
の波長の波が放射され続ける場合を表す。波長が一定でも、放射がとぎれとぎれであったりすれば、
それは周波数解析的に考えればいろいろな周波数の波動が含まれていることになる。)の振る舞
いを考えるわけであるが、これは明らかにコヒーレントな光波の扱いである。
そして、それら点光源が多数集まり像を形成すると考えて良いのであるが、光学設計の多くの
場合には、これ等の点光源、点像に関しては互い放射光に関して、その位相的には相関が無く、
無秩序に発光し、互いに干渉しない、干渉縞など生成しない、と考えるインコヒーレントな物体面を
想定する。また、実際にその様な被写体が多く存在するわけである。
しかし良く考えてみると、光源内の 2 つの点光源同士の位相が一致しなくとも、それぞれから
完全に単色の光波が出ていれば、波連は無限に続くわけであるから隣接光源同士の光波の位相
関係は一定となり、観測に際しての時間平均をとっても、ヤングの干渉実験の如くに干渉が観測で
きることになる。実際のインコヒーレント光源においては周波数幅をある程度もっていたり、波が断
続的に放射されたりしてこうしたことは起こらない。いずれにしても上述の通り、ある微小な周波数
帯域、波長幅を想定しないとインコヒーレントな光源というものが成立しない。
そこで、“極微小な波長幅で色々な波がある程度混在している”、とすれば様々な組み合わせ
で若干波長が異なろうとも狭義の干渉が起こるのであるが、これ等の干渉状態は、波長が僅かにで
も異なるので時間とともに変化し、時間平均の観測を経れば(広義の)これらによる干渉縞は現れ
ないことになる。また同一波長の光波同士も、初期の位相関係が波長ごとにランダムに異なればそ
れぞれ異なる位置にランダムに干渉縞が生成され、それら無数の縞が重なり合い干渉は観察でき
ない。
また、上述の点対点の光源-像の関係を考えるときには、波長域が非常に狭いとすれば、こ
れまで考えてきたコヒーレント結像の理屈が成り立つような都合の良い光波が想定出来れば良い。
これを準単色光と呼ぶ。以下、この準単色光について、そしてそこから得られる部分的コヒーレント
結像の表現について考えよう。