Caption: Microscope images of graded gratings with different gradients. In this measurement, three filters are employed: (a) A multi-band filter (Semrock, transmission bands centered at 542nm and 639nm). (b) A green filter centered at 546nm (bandwidth 6nm). (c) A red filter centered at 655nm (bandwidth 12nm).
Credit: Filbert J. Bartoli, Lehigh University
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