Abstract
PROF. R. W. WOOD, in delivering the Thomas Young Oration at the Optical Society on Thursday, September 29, described some apparatus with which he has been experimenting recently. The first of these, which he calls the echelette grating, is an instrument occupying a position between the echelon and the ordinary diffraction grating. It is a grating ruled with a crystal of carborundum on gold deposited on copper; the carborundum has the advantage over a diamond point of having perfectly straight sides meeting at an angle of 120°. The spacing is about ten times as coarse as usual. No metal is removed in ruling, but the gold is compressed so as to form ridges and hollows. The sides of these ridges are highly polished and almost optically flat. Such a grating may have various faults, such as having a flat or irregular top to the ridges, or the sides of one groove may be deformed in ruling the next; tests to determine whether the grating is free from faults were described.
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The Thomas Young Oration . Nature 84, 443 (1910). https://doi.org/10.1038/084443a0
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DOI: https://doi.org/10.1038/084443a0