. . "echelon"^^ . "03263474-n"^^ . . . . . "103263474"^^ . . . . . . . . . "103144797"@en-us . . . "0"^^ . "a diffraction grating consisting of a pile of plates of equal thickness arranged stepwise with a constant offset"@en-us . . . "echelon"@en-us . "a diffraction grating consisting of a pile of plates of equal thickness arranged stepwise with a constant offset"@en-us . . "102621171"@en-us . . . . "0"^^ . . . .