Newport Cornerstone 130B, Руководство пользователя

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90088262 MCS130B
CORNERSTONE 130B MONOCHROMATORS
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7
6B
MONOCHROMATOR RESOLUTION
Gratings are available in various groove densities (i.e. lines/mm). Higher groove densities give higher
reciprocal dispersion and therefore higher resolution. The monochromator bandpass with a 1200
lines/mm grating is half that of the same arrangement with a 600 lines/mm grating. Note that t his simple
relationship is not accurate for slit widths below 50 µm, as the optical aberrations begin to play a role in
the bandpass and resolution.
Using a grating with a high groove density may increase resolution, but the spectral range narro ws . The
dispersion of a grating changes inversely with the groove density. If the groove density is halved, the
dispersion is doubled. A monochromator mechanism can only tilt the grating through a limit ed range of
angles. The angle and groove density determine the transmitted wavelength.
The gratings can be tilted to 0 degrees, so the lowest possible wavelength for a UV grating is s et by t he
transmittance of air at about 180 nm. A MPT plug is available to connect a hose barb and purge the
monochromator compartment with nitrogen, if desired. The ability to output wavelengths below 180 nm is
also dependent on the efficiency characteristics of the grating.
The following graphs are intended to illustrate the effects of slit width selection, in terms of throughput and
resolution. This data was taken using Oriel’s Tunable Light Source (TLS) systems, using various slit
widths to change the resolution. The TLS systems employ a Cornerstone 130 monochromator.
Figure 16: Resolution vs. Throughput