Diffraction Grating

Diffraction Grating

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Concave speculum metal diffraction grating with 15,000 lines per inch and a 21-foot radius of curvature, that was used with the large Wadsworth spectrograph at the National Bureau of Standards, also in the collection. The plate was probably figured by John A. Brashear in Pittsburgh, and the ruling done on the Rowland engine at the Johns Hopkins University.
Ref: W. F. Meggers and Kievin Burns, “Notes on Standard Wave Lengths, Spectrographs, and Spectrum Tubes,” Scientific Papers of the Bureau of Standards 18 (1922): 185-199.
Currently not on view
Object Name
concave grating
overall: 2 1/2 in x 7 3/8 in x 7 1/4 in; 6.35 cm x 18.7325 cm x 18.415 cm
ID Number
catalog number
accession number
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Medicine and Science: Physical Sciences
Data Source
National Museum of American History
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