Hartridge prism
1984
Replica of Rowland's Diffraction Grating
1905-1915
Diffraction grating with focal power
1973-1983
Pair of glass crossed diffraction gratings in single mount
1900-1956
Thorpe diffraction grating 14950 lines per inch
Circular diffraction gratings
Ultraviolet grating spectrophotometer
Circular diffraction grating
Diffraction Grating
1910-1915
Diffraction Grating on Glass
Two Diffraction Gratings
Thorpe's Transparent Relica of Rowland's Diffraction grating
Diffraction ruling on glass sheet
Perkin-Elmer 257 IR grating spectrometer.
circa 1980
Diffraction grating 1800 gr/mm on 6 inch diameter blank
selection of 8 sets of diffraction rulings on polished steel
1820-1829
Ebert grating spectrograph E543 by Hilger & Watts Ltd.
1967-1968
Circular diffraction grating
Thorp Replica Diffraction Gratings
Diffraction grating
Diffraction grating
1963