M74050
1/4M IMAGING SPECTROGRAPHS
20
6 DIFFRACTION GRATINGS
Diffraction gratings are used to disperse light, i.e. to spatially separate light of different wavelengths. They
have replaced prisms in most fields of spectral analysis. Two or three gratings are installed into the MS260i
spectrograph, depending upon the configuration selected. In general, the grating with the highest efficiency
is chosen at a particular wavelength. The optional Oriel TracQ
™ Basic Data Acquisition and Radiometery
Software allows users to set up a specific grating switchover wavelength, so the most appropriate grating
will automatically be chosen while performing a scan over a range of wavelengths.
The MS260i spectrographs feature diffraction gratings produced by Richardson Gratings. Both Oriel
Instruments and Richardson Gratings are part of the Newport family of brands, and have a long history of
working together to design spectrographs that are appropriate for a wide variety of applications.
A tutorial on grating physics may be found in the Appendix of this user’s manual.
The photo below illustrates diffraction gratings mounted into holders for installation into the MS260i
spectrograph. The grating is precisely positioned on the mount using a fixture, and then the grating angle
is aligned by Oriel, with the screws locked into place using the red adhesive. An unmounted grating cannot
be installed by the user in the field; gratings must be installed onto the appropriate mount for the MS260i
spectrograph and aligned at the factory. The mount differs, depending on whether it is a dual-grating or
triple-grating instrument configuration.
Figure 14: Gratings Installed onto Mounts