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concave diffraction grating
concave diffraction grating

concave diffraction grating

Date1920-1940
Inventory Number1998-1-1324
ClassificationDiffraction Grating
Subject
    Maker American
    User Department of Physics, Harvard University founded 1884
    Cultural Region
      Dimensionsgrating: 1.5 × 10 × 10 cm (9/16 × 3 15/16 × 3 15/16 in.)
      box: 11 × 14.8 × 15.1 cm (4 5/16 × 5 13/16 × 5 15/16 in.)
      Material
        DescriptionConcave diffraction grating made of speculum metal. The number of lines per inch and the radius of curvature are unknown. The number "49" has been etched in one corner. The grating is screwed in place in the box.
        Signedunsigned
        FunctionA diffraction grating is a glass or mirror that has regularly spaced microscopic interruptions to the passage of light (lines) such that light passing through or reflected by it experiences interference phenomena, magnifying its magnitude at some angles and cancelling it at others. As this effect depends on the wavelength of light, a diffraction grating is an effective method of decomposing light into its constituent wavelengths, that will be transmitted at different angles (short wavelengths -- bluer -- are deflected less than longer -- redder -- ones). If one knows the line density (lines per inch) and the angle of deflection (with a spectrometer), one can deduce the exact wavelengths.

        Diffraction gratings like this one were often used in astronomy to produce spectra of celestial objects. Begun in 1882, Rowland's gratings were more than an order of magnitude larger and more accurate than any previous one. With these, for instance, it became possible to measure the wavelength of light emitted by atoms to unprecedented accuracy. Rowland himself was able to draw a new and more accurate map of the solar spectrum.

        For more information go to the following website.
        ProvenanceJefferson Laboratory, Department of Physics, Harvard University; transferred to CHSI January 19, 1977.
        concave diffraction grating
        concave diffraction grating
        American
        Date: circa 1925
        Accessories: metal box
        Object number: 2027
        concave diffraction grating
        concave diffraction grating
        American
        Date: 1910-1940
        Object number: 2042
        concave diffraction grating
        concave diffraction grating
        American
        Date: circa 1924
        Accessories: wooden box
        Object number: 2025
        concave diffraction grating
        concave diffraction grating
        Bausch & Lomb Optical Company
        Date: circa 1915
        Object number: 2032
        concave diffraction grating
        concave diffraction grating
        American
        Date: 1908-1912
        Accessories: wooden box
        Object number: 2029
        concave diffraction grating
        concave diffraction grating
        American
        Date: 1903
        Object number: 2041
        Rowland concave diffraction grating
        Rowland concave diffraction grating
        Henry A. Rowland
        Date: 1894
        Accessories: box
        Object number: 2033
        concave diffraction grating
        concave diffraction grating
        Adam Hilger Ltd.
        Date: circa 1923
        Accessories: wooden box
        Object number: 2039
        concave diffraction grating
        concave diffraction grating
        Robert W. Wood
        Date: 1927
        Accessories: aluminum box
        Object number: 2026
        concave diffraction grating
        concave diffraction grating
        Robert W. Wood
        Date: circa 1925
        Accessories: wooden box
        Object number: 2040
        Rowland concave diffraction grating in stand
        Rowland concave diffraction grating in stand
        Henry A. Rowland
        Date: 1897
        Object number: 2037
        wood concave diffraction grating
        wood concave diffraction grating
        Robert W. Wood
        Date: 1932
        Accessories: wooden case
        Object number: 2024