The Cornu Prism Spectrometer

The large Littrow-type instrument has a focal length of 1.8 m and can be used over a spectral range of 2000-8000 A with a quartz prism. This spectral range requires the use of 30 in. of photographic plates. The spectral range can be increased to 10,000 A by use of a glass prism. 

FIGURE 4-2. Schematic diagram of a Littrow prism spectrometer. 

The two most-used large Littrow spectrometers are those produced by Bausch and Lomb and by Adam Hilger, Ltd. The instruments have similar specifications however, the Hilger unit combines all three wavelength 

FIGURE 4-3. Photograph of a large Littrow spectrograph (no longer being manufactured). [Courtesy Bausch and Lomb Optical Company.] 

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